Composite fibers and methods for making the same, and articles

Abstract

This application discloses a composite fiber, its preparation method, and the resulting product. The composite fiber comprises polyester, cross-linked sodium polyacrylate, and a degradation agent; the cross-linking density of the cross-linked sodium polyacrylate is 1.0 × 10⁻⁶. ‑4 –6.0×10 ‑4 mol / cm 3 The particle size is 200-800 nm; the polyester forms a continuous phase, and the cross-linked sodium polyacrylate forms a dispersed phase distributed within the continuous phase, together constituting the sea-island structure of the composite fiber. This application achieves rapid moisture wicking by combining cross-linked sodium polyacrylate with polyester to form micro-nano channels within the fiber.

Description

Technical Field

[0001] This application relates to the field of textile materials, and in particular to a composite fiber capable of rapid moisture absorption and wicking away, a method for preparing the same, and articles derived from the composite fiber. Background Technology

[0002] With increasing global environmental awareness, polyester fibers, which are widely used in traditional sportswear, face serious challenges due to their slow degradation and microplastic pollution. Meanwhile, poor comfort caused by sweat buildup during exercise is also a major pain point for the industry. Summary of the Invention

[0003] To address at least one of the aforementioned problems, this application discloses a composite fiber, its preparation method, and the resulting product. The composite fiber forms micro-nano channels within the fiber through selective selection of constituent raw materials. These micro-nano channels can intelligently respond to the ion concentration in sweat, expanding at high concentrations to facilitate rapid perspiration. The composite fiber provided by this application achieves intelligent perspiration response and can rapidly and directionally degrade after disposal, making it environmentally friendly.

[0004] The first aspect of this application discloses a composite fiber, which may include: a polyester continuous phase and a cross-linked sodium polyacrylate dispersion dispersed in the polyester continuous phase, wherein the cross-linked sodium polyacrylate dispersion and the polyester continuous phase form a sea-island structure, thereby forming micro-nano channels inside the composite fiber; the composite fiber also includes a degrading agent; wherein the cross-linking density of the cross-linked sodium polyacrylate is 1.0 × 10⁻⁶. -4 –6.0×10 -4 mol / cm 3 The particle size is 200-800nm; the micro-nano channels in the sea-island structure are configured to expand when the external ion concentration exceeds a preset threshold, driven by the water absorption and swelling of the cross-linked sodium polyacrylate, so as to achieve rapid moisture wicking.

[0005] According to some embodiments of this application, the weight-average molecular weight of the cross-linked sodium polyacrylate can be 5000-10000.

[0006] According to some embodiments of this application, the micro-nano channel has a first pore size when the external ion concentration is below a predetermined concentration, and a second pore size when the concentration is not below the first concentration; the second pore size is at least 300% of the first pore size.

[0007] According to some embodiments of this application, the difference in solubility parameters between the crosslinked sodium polyacrylate and the polyester is greater than 5 (J / cm³)^(1 / 2).

[0008] According to some embodiments of this application, the degrading agent may have at least hydroxyl and lactone groups.

[0009] According to some embodiments of this application, the proportion of the hydroxyl group and the lactone group in the total number of functional groups in the degrading agent may be no less than 75%.

[0010] According to some embodiments of this application, the mass ratio of the polyester, the cross-linked sodium polyacrylate, and the degradation agent can be (90.0-98.5):(1.0-7.0):(0.5-3.0).

[0011] The second aspect of this application provides a method for preparing the composite fiber as described above. The method may include: S1. providing polyester, cross-linked sodium polyacrylate, and a degradation agent, pre-treating them, and then melt-blending them to obtain a melt-spinning raw material; S2. using the melt-spinning raw material to perform melt spinning, and subjecting the obtained nascent fiber to step-cooling, wherein the step-cooling is achieved by setting a slow cooling zone to delay the crystallization and nucleation process of the continuous polyester phase, providing a kinetic window for the directional migration of the cross-linked sodium polyacrylate dispersed phase, so that it is arranged in an orderly manner along the fiber radial direction to form a continuous and stable micro-nano channel precursor structure; S3. post-treating the cooled nascent fiber to obtain the composite fiber.

[0012] According to some embodiments of this application, the pretreatment in S1 includes: drying the polyester, the cross-linked sodium polyacrylate, and the degradation agent, and then mixing the dried cross-linked sodium polyacrylate with the degradation agent to obtain active particles.

[0013] According to some embodiments of this application, the stepped cooling in S2 includes passing the nascent fiber through a slow cooling zone, wherein the temperature range of the slow cooling zone is 240℃-120℃ and the temperature gradient is 1-2℃ / cm.

[0014] According to some embodiments of this application, the post-processing in S3 includes stretching, shaping, and winding.

[0015] A third aspect of this application provides an article which can be manufactured from the composite fiber as described above, or from the composite fiber prepared by the method described above.

[0016] The composite fiber provided in this application achieves rapid liquid absorption and conduction through the combined use of a polyester substrate and cross-linked sodium polyacrylate, keeping the material dry during use. Simultaneously, the addition of a degradation agent allows for rapid degradation after material disposal without affecting material performance, and the degradation products are environmentally friendly.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Detailed Implementation

[0018] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application and in its specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The terms "comprising" or "including," as used in this application, mean that an element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms "and / or" or "and / or" as used in this application include any and all combinations of one or more of the associated listed items.

[0020] As mentioned in the background section, traditional sports fabrics possess moisture-wicking and perspiration-absorbing properties (such as DuPont Coolmax). ® (Represented by) This method utilizes capillary action to wick moisture through irregular fiber cross-sections (e.g., cross-shaped, Y-shaped, etc.). However, the material is traditional polyester, which is non-biodegradable and causes permanent pollution after disposal. Furthermore, to achieve antibacterial and odor-resistant properties, silver ions, zinc ions, or quaternary ammonium salt finishing agents are mainly used, which present problems such as metal ion release pollution, poor wash resistance (usually failing after 20-30 washes), and do not address the degradation of the fiber matrix. Other solutions for adapting to humid and hot environments in sports fabrics include phase change temperature regulation technology (such as Outlast). ® This technology achieves temperature regulation by encapsulating phase change materials in microcapsules. However, the microcapsules themselves may become a source of microplastic pollution, and their function is unrelated to their degradability.

[0021] In addition, current technologies related to biodegradable textile materials include two main types. One is bio-based biodegradable fibers, such as polylactic acid (PLA) fibers. While the technology is relatively mature, it has significant limitations. First, the degradation conditions are demanding: requiring an industrial composting environment (58-60°C, specific humidity and microbial flora), and degradation is extremely slow in natural environments. Second, it suffers from performance defects: poor heat resistance (glass transition temperature approximately 55-60°C), inability to withstand alkaline washing, and easy hydrolysis. Third, it presents recycling challenges, being incompatible with PET recycling systems and compromising the quality of recycled materials after mixing. Other bio-based materials, such as PHA and PHBV, are expensive (3-5 times that of PET), have immature spinning processes, and low levels of industrialization. The second type of biodegradable textile material is oxidative / photo-oxidative degradable plastics. The technical principle involves adding transition metal salts (cobalt, manganese, etc.) to promote chain scission of plastics under light / heat. However, this approach has been banned by the EU and many other countries (Directive 2019 / 904) because the plastic only disintegrates without degrading, breaking down large plastics into microplastics, making pollution more insidious. Furthermore, toxic residues and the accumulation of metal catalysts in the environment pose a threat. They also interfere with recycling, as metal salts can contaminate traditional plastic recycling processes.

[0022] Based on this, this application provides a composite fiber, a method for preparing the same, and an article thereof. The composite fiber utilizes cross-linked sodium polyacrylate as the liquid-responsive unit, enabling rapid liquid absorption and conduction, thereby keeping the fiber dry. Simultaneously, an environmentally friendly degrading agent is added to the composite fiber, enabling rapid and targeted degradation of the composite fiber without harming the environment.

[0023] The following describes some preferred embodiments of this application. It should be noted that the following description is for illustrative purposes only and is not intended to limit the scope of protection of this application. The steps involved in this application may be performed precisely in sequence, or various steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0024] The composite fiber provided in this application includes polyester, cross-linked sodium polyacrylate, and a degradation agent.

[0025] Polyester can be used as the matrix of the composite fiber to achieve the composite fiber's high strength, abrasion resistance, durability, easy washing, and quick drying properties. Materials such as polyethylene terephthalate (PET), polypropylene terephthalate (PTT), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid (PGA), polybutylene succinate (PBS), polybutylene adipate-butylene terephthalate copolymer (PBAT), polybutylene succinate-butylene terephthalate copolymer (PBST), polycaprolactone (PCL), polypropylene carbonate (PPC), and recycled polyester (rPET) can all be used in this application without limitation.

[0026] Crosslinked sodium polyacrylate can refer to a polymer in which linear sodium polyacrylate is linked by a crosslinking agent to form a three-dimensional network structure. Its crosslinking is essentially achieved by connecting linear chains into an insoluble and infusible three-dimensional network through covalent bonds (e.g., free radical crosslinking) or ionic bonds (e.g., metal ion crosslinking). Because crosslinked sodium polyacrylate has strong water absorption, in order to ensure that the crosslinked sodium polyacrylate only absorbs water and swells without dissolving in the articles made from the composite fibers during use, in some embodiments of this application, its crosslinking density is controlled at 1.0 × 10⁻⁶. -4 –6.0×10 -4 mol / cm 3 For example, the crosslinking density of crosslinked sodium polyacrylate is 1.0 × 10⁻⁶. -4 mol / cm 3 2.0×10 -4 mol / cm 3 3.0×10 -4 mol / cm 3 4.0×10 -4 mol / cm 3 5.0×10 -4 mol / cm 3 6.0×10 -4 mol / cm 3 The quantity can be any increment or decrement of any of the above values, and this application does not impose any specific limitations.

[0027] In addition, to ensure the water absorption ratio of cross-linked sodium polyacrylate and to prevent it from swelling but not dissolving after absorbing water, the weight-average molecular weight of cross-linked sodium polyacrylate can be 5000-10000 Da. This avoids both a decrease in water absorption ratio due to high cross-linking density and dissolution after absorbing water due to low cross-linking density.

[0028] This application utilizes melt spinning to prepare the composite fiber (for polyester with good thermoplasticity and non-decomposition upon melting). The polyester and cross-linked sodium polyacrylate are melt-mixed to obtain a uniform melt, which is then spun, cooled, and solidified. To avoid clogging the nozzles during spinning, in some embodiments of this application, the cross-linked sodium polyacrylate used is in powder form with a particle size of 200-800 nm. For example, the particle size of the cross-linked sodium polyacrylate used can be 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, etc., or any increment or decrease of any of these values. This is because the side chains of the cross-linked sodium polyacrylate have densely distributed ionic sodium carboxylate (-COO). - Na +The cross-linked sodium acrylate (CLA) contains ionic groups, and after forming a three-dimensional network, the density of ionic groups is extremely high, resulting in strong ionic polarity, much higher than that of polyester (due to the presence of polar ester groups (-COO-) and non-polar groups (Ph ring and methylene-CH2-) in the main chain of polyester, exhibiting an alternating structure of "polar-non-polar"). Furthermore, compared to the strong water absorption of CLA, polyester has extremely low water absorption and is generally hydrophobic, leading to a significant difference in their solubility parameters. In some embodiments, the difference in solubility parameters between CLA and polyester can be greater than 5 (J / cm³)^(1 / 2). Based on the above reasons, namely the difference in polarity and solubility parameters between polyester and CLA, microphase separation inevitably occurs during melt blending. Polyester will form a continuous phase (or "sea"), while CLA will form a dispersed phase (or "island"). Highly polar cross-linked sodium polyacrylate will be dispersed in the form of nano-sized particles within a non-polar continuous polyester phase, resulting in an overall "sea-island" structure. Simultaneously, the composite fiber will undergo a stepped cooling process (or slow cooling) during molding, thereby slowing down the crystallization rate of the polyester matrix. During this process, the cross-linked sodium polyacrylate will be induced to align orderly at the interface between the two phases, forming continuous and stable micro-nano channels.

[0029] According to some embodiments of this application, the micro / nano channel has a first pore size when the external ion concentration is below a predetermined concentration, and a second pore size when the external ion concentration is not lower than the first concentration; the second pore size is at least 300% of the first pore size. Due to the strong water absorption of cross-linked sodium polyacrylate, in a humid environment, for example, when it is made into sportswear and worn by a user during exercise, based on the ion osmotic pressure effect, when the external ion concentration, such as the sweat ion concentration, exceeds a predetermined concentration, such as 0.3 mol / L (e.g., sodium ion concentration, or the combined molar concentration of sodium, potassium, calcium, and magnesium ions), the cross-linked sodium polyacrylate will undergo a hygroscopic response and swell. Due to the limitations of the three-dimensional network structure, the resulting physical expansion force will cause the formed micro / nano channel to expand. Exemplarily, the micro / nano channel will have a first pore size when the external ion concentration is less than the predetermined concentration, and a second pore size when the external ion concentration is not lower than the predetermined concentration. The second pore size is at least 300% of the first pore size; for example, the second pore size will expand to at least 400% of the first pore size, thereby achieving rapid moisture wicking. When in a dry environment (i.e., when the external ion concentration is less than the predetermined concentration), due to the elastic properties of the three-dimensional structure of cross-linked sodium polyacrylate, the micro-nano channels can be automatically contracted to restore the first pore size, thereby realizing the dynamic size adjustment of the microstructure of the composite fiber.

[0030] The degrading agent will achieve the directional degradation of the composite fibers. In some embodiments of this application, compounds having hydroxyl and lactone groups can be used as the degrading agent. The lactone group provides slow acidity and degradation kinetics, and will hydrolyze under aqueous, moist, and / or heated conditions to generate carboxylic acids. The released hydrogen ions H... + The degradation of polyester can be achieved by acid-catalyzing the cleavage of ester bonds. Hydroxyl groups have strong hygroscopic properties, absorbing moisture to activate the acidification of lactone groups and stabilize the carboxylic acid structure, allowing for a more gradual release of acidity. Based on this, a degradation agent (achieved through melt mixing) uniformly distributed within the composite fiber, when the composite fiber is in a continuously humid environment (e.g., after disposal and landfill), will facilitate rapid liquid conduction through micro-nano channels formed by cross-linked sodium polyacrylate, allowing moisture to quickly penetrate into the interior of the composite fiber. The degradation agent, based on the hydroxyl group's water absorption, induces the lactone groups to undergo ring-opening hydrolysis, releasing catalytically active carboxyl groups (-COOH) in situ, forming an acidic environment. This acidic environment acts as a proton center, accelerating the hydrolysis of ester bonds in the polyester, directionally converting the macromolecular chains into carbon dioxide (CO2) and water (H2O), achieving complete biodegradation with no microplastic residue, which is environmentally friendly.

[0031] In some embodiments of this application, the degrading agent may include aldose derivatives, such as glucose derivatives like D-gluconic acid-δ-lactone (GDL), D-gluconic acid-γ-lactone, D-glucuronide, etc.; mannose derivatives like D-mannonic acid-δ-lactone, D-mannonic acid-γ-lactone, etc.; galactose derivatives like D-galactononic acid-δ-lactone, D-galactononic acid-γ-lactone, etc.; or other aldoses such as D-aloose, D-gulose, D-idolose, D-tarose, etc., and their corresponding gluconic acid-δ-lactones or gluconic acid-γ-lactones, or any combination thereof. The content of the lactone group and the hydroxyl group in the degrading agent may exceed 75%. The content may refer to the percentage of the total number of lactone groups and the hydroxyl group in the total number of functional groups contained in the degrading agent. This ensures that the degrading agent effectively catalyzes the ester bond of the polyester in an aqueous system, causing it to break.

[0032] In the composite fiber, the mass ratio of the polyester, the cross-linked sodium polyacrylate, and the degrading agent can be (90.0-98.5):(1.0-7.0):(0.5-3.0). A higher content of polyester serves as the main component of the composite fiber, achieving advantages such as high strength, high abrasion resistance, wrinkle resistance, elasticity, easy washing, and quick drying. A lower content of cross-linked sodium polyacrylate is used to form micro-nano channels in the polyester, preventing the composite fiber from being unable to spin during preparation due to a high content. A small amount of the degrading agent acts as an initiator for the directional degradation of the composite fiber, ensuring environmental friendliness.

[0033] In some embodiments of this application, the composite fiber may further include a light stabilizer. Based on the foregoing description, when the composite fiber is applied to sportswear or outdoor equipment, it enables these garments / equipment to have excellent moisture-wicking properties. Depending on the application scenario of the sportswear or outdoor equipment, the composite fiber may also contain a light stabilizer to enhance its stability against ultraviolet radiation. Compounds such as carbon black, zinc oxide (ZnO), titanium dioxide (TiO2), nano-montmorillonite, benzotriazole compounds, benzophenone compounds, triazine compounds, salicylates, cyanoacrylates, hydrotalcite-supported rare earth cerium complexes, nickel organic complexes, cobalt / iron complexes, hindered phenolic derivatives, and hindered amine compounds, which can achieve light shielding or ultraviolet absorption / capture, can all be used as light stabilizers in this application.

[0034] The composite fiber provided in this application enables rapid liquid absorption and wicking (e.g., rapid moisture absorption and perspiration), thereby keeping the fiber dry. Simultaneously, environmentally friendly degradable agents are added to the composite fiber, enabling rapid and targeted degradation of the composite fiber without harming the environment.

[0035] This application also provides a method for preparing the composite fiber as described above. As an exemplary but not limiting illustration, the method for preparing the composite fiber may include the following steps.

[0036] Step S1: Provide polyester, cross-linked sodium polyacrylate and degradation agent, pre-treat and then melt blend to obtain melt spinning raw material.

[0037] Step S2: Melt spinning is performed using the aforementioned melt spinning raw material, and the resulting nascent fibers are cooled in a stepped manner. Step S3: Post-process the cooled nascent fibers to obtain the composite fibers.

[0038] For step S1, the pretreatment may include drying the polyester, the cross-linked sodium polyacrylate, and the degrading agent, and then mixing the dried cross-linked sodium polyacrylate with the degrading agent to obtain active particles. This also includes premixing the dried polyester and the active particles. In some implementations, the polyester, the cross-linked sodium polyacrylate, and the degrading agent may be weighed according to a predetermined mass and then dried under vacuum. For example, drying at 80°C for 6 hours in a vacuum dryer. The purpose of drying may be to reduce the moisture content in the raw materials. For example, the drying parameters (including temperature and time) may reduce the moisture content in the raw materials to below 50 ppm. Low moisture content prevents polyester hydrolysis at high temperatures and maintains stable intrinsic viscosity. For example, maintaining the intrinsic viscosity of the polyester at 0.65 ± 0.02 dL / g helps determine the melt flowability and fiber-forming properties during subsequent melting.

[0039] The drying of the cross-linked sodium polyacrylate and the drying of the degradation agent can be performed using an internal mixer. Any internal mixer with any rotor type, such as Banbury type, meshing type, pin type, or corrugated type, can be used in this application. Internal mixing can initially bond the cross-linked sodium polyacrylate and the degradation agent through an ester exchange reaction to obtain active particles, thereby ensuring the uniform dispersion of the active particles in the matrix during subsequent mixing, avoiding the agglomeration of the cross-linked sodium polyacrylate, and thus ensuring the uniformity of liquid response and degradation.

[0040] The active particles and dried polyester can be melt-blended to obtain a melt-spinning raw material. An exemplary operation may include: first adding the active particles and dried polyester to a mixing device for premixing. The mixing device used can be any device capable of mixing, such as a horizontal mixer, vertical mixer, double cone mixer, V-type mixer, trough mixer, kneader, planetary mixer, fluidized bed mixer, spiral cone mixer, belt mixer, tipping bucket mixer, airflow mixer, high-speed mixer, slurry mixer, vacuum mixer, etc. Taking dry mixing as an example, after the components are added to the high-speed mixer, they can be mixed at a preset stirring speed (e.g., 500-800 rpm) for a set time (e.g., 5-15 min) to obtain a premix. Premixing allows the active particles to be initially and uniformly dispersed in the polyester. Subsequently, the premix is ​​fed into a twin-screw extruder for melt blending. The material undergoes melting, dispersion, and homogenization under the shearing, conveying, and heating action of the screw. The homogenized melt is then conveyed, pushed by the screw to a filter plate and screen to remove particles and impurities before entering the die head (e.g., a round-hole die head), where it is extruded through the die holes to form a continuous "strip." A suitable pelletizing method (e.g., water-cooled pelletizing) is selected to cut this continuous strip into uniform pellets. These pellets can then undergo necessary processing such as drying, sieving, and quality inspection before being used as the final melt spinning raw material.

[0041] In the above process, to prevent cross-linked polyacrylic acid from decomposing and yellowing at high temperatures, the processing temperature gradient of the twin-screw extruder can be set to 240℃→260℃→275℃→275℃→270℃ (from the feed inlet to the die head). Meanwhile, since cross-linked sodium polyacrylate consists of nano-cross-linked particles, to avoid excessive breakage or agglomeration and blackening due to high shear, the screw speed can be set to 200-300 rpm.

[0042] For the melt spinning in step S2, a single-screw extruder can be used. For example, granular melt-spinning raw materials can be processed through melt formation and spinneret formation to obtain the nascent fibers. The spinning temperature during melt formation can be consistent with the temperature of the aforementioned blending section to ensure melt flowability. The relevant parameters of the spinneret and metering pump, including orifice diameter, number of orifices, and melt output flow rate, can be set according to actual conditions. For example, the granular melt-spinning raw materials are completely melted by shearing and heating in the melt section of the single-screw extruder to form a homogeneous melt. This homogeneous melt can pass through a multi-stage filter or melt filter to remove unmelted particles, mechanical impurities, etc., before entering the gear metering pump. The melt output flow rate is controlled by the precise speed of the pump. This ensures that the melt extrusion rate of each spinneret orifice is consistent. The metered melt is evenly distributed to the spinneret through the melt pipeline of the spinning box, and under pressure, it passes through the spinneret orifices to form a continuous melt stream, serving as the viscous nascent fiber.

[0043] The viscous nascent fibers can be cooled in a stepped manner rather than rapidly quenched to solidify. This stepped cooling refers to setting up a temperature gradient zone (or slow cooling zone) where the viscous nascent fibers are cooled at a lower rate after passing through. For example, the temperature range of the slow cooling zone can be 240℃-120℃, with a temperature gradient of 1-2℃ / cm. The length of this zone is 1-1.5m. This reduces the cooling rate of the viscous nascent fibers to 1 / 5-1 / 3 of the conventional quenching rate. In other words, the reduced cooling rate of the viscous nascent fibers thermodynamically slows down the nucleation process in the polyester matrix. This nucleation window provides the kinetics for the directional migration of cross-linked sodium polyacrylate, promoting the orderly arrangement of the cross-linked sodium polyacrylate phase structure within the polyester matrix, thereby forming a highly responsive and stable continuous micro / nano channel precursor structure.

[0044] For step S3, the post-processing may include stretching, setting, and winding. Stretching can be used to improve the orientation of molecular chains and enhance fiber strength. In some implementations, stretching may be thermal stretching. For example, the stretching temperature may be 80°C, the stretch ratio may be 3.5 times, and two-stage stretching may be used. Setting can be used to eliminate internal stress, fix the fiber structure, and stabilize the crystalline morphology. Setting can be performed using various applicable setting methods, including but not limited to dry heat setting (e.g., placing the wound fiber in a hot air setting oven to eliminate internal stress and improve crystallization under heat), wet heat setting (e.g., immersing the fiber in a constant temperature water body or introducing it into atmospheric pressure saturated steam to eliminate internal stress), and steam setting (e.g., atmospheric pressure steam setting, high pressure steam setting, etc., using saturated steam to rearrange the fiber's molecular chains and form stable crystals). Specific adjustments can be made according to actual conditions. For example, heat setting at 120°C for 30 seconds. Winding can be the regular winding / winding of continuous fibers to obtain the final product. At a suitable winding speed (e.g., 2500–3000 m / min) and winding ratio (350–500), the final fiber product will be obtained.

[0045] This application also provides an article, which can be made from the aforementioned composite fiber or composite fiber obtained by the preparation method. Such articles can include clothing (including but not limited to outerwear, formal wear, sportswear, skirts, trousers, underwear, workwear, etc.), home textiles (including but not limited to bedding, curtains, towels, bath towels, blankets, etc.), outdoor travel products (including but not limited to tents, umbrella fabrics, tarpaulins, sleeping bags, backpacks, etc.), medical and hygiene products (including but not limited to disposable surgical gowns, medical leaflets, non-woven fabrics, bandages, etc.), and decorative advertising materials (including but not limited to inkjet printing cloth, wall coverings, bag fabrics, etc.).

[0046] The present application will be further described in detail below with reference to embodiments. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection claimed in this application.

[0047] Example - Preparation of Composite Fibers The method for preparing composite fibers according to this application is described in detail below through several embodiments. Each embodiment uses the following general process, differing only in the selection of raw materials, proportions, and process parameters.

[0048] Example 1 - Preparation of Composite Fibers In this embodiment, PET and cross-linked PAAS (3000 ppm) were blended, and GDL was used as the degradation agent. The mass ratio of the three was 95:3:2. The specific preparation steps are as follows: Step S1 (Pretreatment and Melt Blending): (1) Drying: PET chips (intrinsic viscosity 0.65 dL / g), cross-linked sodium polyacrylate powder (cross-linking density 3.0 × 10-4 mol / cm³, weight-average molecular weight 8000 Da, particle size 500 nm), and degradation agent D-gluconic acid-δ-lactone (GDL) were placed in a vacuum drying oven and dried at 80℃ for 6 hours to ensure that the moisture content was below 50 ppm. (2) Preparation of active particles by mixing: The dried cross-linked sodium polyacrylate and GDL were added to a Banbury mixer at a mass ratio of 3:2. The mixing temperature was 160℃, the rotor speed was 60 rpm, and the mixing time was 10 min. During the mixing process, the sodium carboxylate groups on the surface of the cross-linked sodium polyacrylate underwent an ester exchange reaction with the hydroxyl groups of GDL, so that GDL was covalently grafted onto the surface of the three-dimensional network of cross-linked sodium polyacrylate to form active particles. The obtained active particles were cooled, pulverized, and passed through a 200-mesh sieve for later use. (3) Premixing and melt blending: Active granules and dried PET chips are added to a high-speed mixer at a ratio of PET:active granules = 95:5, where the effective mass ratio of PAAS to GDL in the active granules is 3:2. The mixture is mixed at 800 rpm for 10 min to obtain a premix. The premix is ​​then fed into a twin-screw extruder for melt blending. The temperature gradient from the feed inlet to the die head of the extruder is: 240℃→260℃→275℃→275℃→270℃, and the screw speed is 250 rpm. After the melt is homogenized by a static mixer, impurities are removed by a filter plate (200 mesh), and then it is extruded through a round die (3mm aperture), water-cooled (25℃), and pelletized to obtain melt spinning raw material particles with a diameter of 3mm and a length of 3-5mm. Step S2 (Melting and Stepped Cooling): The above-mentioned melt-spinning raw material particles are added to a single-screw extruder. The temperature of the extruder's melting section is 270°C. The melt is pumped to the spinneret (72 holes, 0.3 mm diameter) via a metering pump (output flow rate 2.4 g / min / hole), and extruded under a pressure of 8 MPa to form a fine melt stream. The extruded viscous nascent fibers immediately enter a 1.2 m long stepped cooling zone. The temperature gradient in the cooling zone is precisely controlled by a zoned heating jacket, from 240°C (inlet) → 200°C → 170°C → 140°C → 120°C (outlet), with a temperature gradient of approximately 1°C / cm. The nascent fibers pass through this cooling zone at a winding speed of 800 m / min, with a residence time of approximately 0.09 s. Under these slow cooling conditions, the crystallization and nucleation process of the polyester matrix is ​​delayed, and the cross-linked sodium polyacrylate nanoparticles are ordered along the radial direction of the fiber under thermal motion, forming a continuous micro-nano channel precursor structure. After passing through the slow cooling zone, the fibers enter the 25°C side-blowing zone (wind speed 0.5m / s) to complete the final curing; Step S3 (Post-processing): The cured nascent fibers are subjected to the following steps in sequence: (a) Hot drawing: First-stage drawing temperature 80℃, draw ratio 2.5; second-stage drawing temperature 90℃, draw ratio 1.4; total draw ratio 3.5, drawing speed 800m / min. (b) Heat setting: Setting in a 120℃ hot air oven for 30s. (c) Winding: Winding speed 2800m / min, winding ratio 420, to obtain the finished composite fiber (monofilament fineness 2.2dtex).

[0049] Example 2 - Preparation of Composite Fibers The differences between this embodiment and Example 1 are as follows: (1) The polyester matrix is ​​replaced with PBT (intrinsic viscosity 0.85 dL / g, melting temperature 225℃); (2) The crosslinking density of the crosslinked sodium polyacrylate is increased to 5.0×10-4 mol / cm³ (weight-average molecular weight 6000 Da, particle size 300 nm) to verify the stability of water absorption and swelling without dissolution under higher crosslinking density; (3) The degradation agent is replaced with D-glucuronide, with a total proportion of hydroxyl and lactone groups of 82%. (4) The ratio was adjusted to PET / PAAS / GDL=92:5:3 (lower proportion of base material and higher proportion of functional additives); (5) The temperature gradient of the twin-screw extruder was adjusted accordingly to: 230℃→250℃→265℃→265℃→260℃ (to match the melting characteristics of PBT); (6) The melt spinning temperature was 260℃, and the temperature gradient of the slow cooling zone was 230℃→120℃; (7) The heat setting temperature was adjusted to 110℃ (to match the crystallization characteristics of PBT). The remaining process parameters were the same as in Example 1.

[0050] Example 3 - Preparation of Composite Fibers The difference between this embodiment and Example 1 is as follows: (1) The polyester matrix is ​​replaced with recycled polyester rPET (intrinsic viscosity 0.60 dL / g, obtained by washing, crushing, melting and re-granulating recycled PET bottle flakes) to verify the downgraded recycled PET reuse scenario of this application; (2) The crosslinking density of crosslinked sodium polyacrylate is reduced to 1.0×10-4 mol / cm³ (weight average molecular weight 10000 Da, particle size 700 nm) to verify the balance between the hygroscopic response and anti-solubility of PAAS under low crosslinking density; (3) The degradation agent is replaced with D -Mannosic acid-δ-lactone, the total proportion of hydroxyl and lactone groups is 78%; (4) The ratio is adjusted to rPET / PAAS / degrader = 97:2:1 (the base material accounts for more than 95%, and the total amount of functional additives is 3%); (5) The temperature gradient of the twin-screw extruder is: 235℃→255℃→270℃→270℃→265℃ (to match the slightly lower intrinsic viscosity of rPET); (6) The melt spinning temperature is 268℃, the temperature gradient of the slow cooling zone is 240℃→120℃, and the length of the slow cooling zone is 1.0m; (7) The total draw ratio is adjusted to 3.2 times. The remaining process parameters are the same as in Example 1.

[0051] Example 4 - Preparation of Composite Fibers The difference between this embodiment and Example 1 is as follows: (1) The polyester matrix is ​​replaced with a blend of PLA and PBAT (PLA:PBAT=70:30 mass ratio) to verify the applicability of this application in a bio-based biodegradable polyester system; (2) The crosslinking density of the crosslinked sodium polyacrylate is 4.0×10-4mol / cm³ (weight-average molecular weight 7000Da, particle size 400nm); (3) The ratio is adjusted to (PLA+PBAT) / PAAS / GDL=94 :4:2; (4) The temperature gradient of the twin-screw extruder is adjusted to: 175℃→190℃→205℃→205℃→200℃ (to suit the lower melting temperature of PLA / PBAT); (5) The drying conditions are adjusted to vacuum drying at 60℃ for 8 hours (to suit the easy hydrolysis characteristics of PLA); (6) The melt spinning temperature is 200℃, the temperature gradient of the slow cooling zone is 180℃→100℃, and the length of the slow cooling zone is 1.0m; (7) The heat setting temperature is adjusted to 90℃; the total draw ratio is 2.8 times. The remaining process parameters are the same as in Example 1.

[0052] Comparative Example 1 - Preparation of Composite Fibers The only difference between this comparative example and Example 1 is that step S2 does not use a stepped cooling slow-cooling zone, but instead uses a rapid cooling process, directly passing the viscous nascent fibers through a 25°C side-blowing zone (wind speed 1.5 m / s) for rapid cooling and solidification (the cooling rate is approximately 5 times that of Example 1). Rapid cooling causes the polyester matrix to crystallize and solidify quickly, and the cross-linked sodium polyacrylate nanoparticles are "frozen" in their randomly distributed initial positions, unable to obtain a kinetic window for directional migration, significantly deteriorating the continuity and orderliness of the micro-nano channels. Test results show that the sweat response channel expansion rate of the fiber obtained in Comparative Example 1 is only 120% (415% in Example 1), and the moisture absorption and wicking rate decreases to 35% of that in Example 1, proving that a stepped cooling slow-cooling zone is a necessary process condition for achieving the ordered arrangement of micro-nano channels.

[0053] Comparative Example 2 - Preparation of Composite Fibers The only difference between this comparative example and Example 1 is that in step S1, the cross-linked sodium polyacrylate and the degradation agent (GDL) are not subjected to an internal mixing step, but are directly added to a high-speed mixer for physical mixing after being dried separately. Due to the lack of transesterification reaction during the internal mixing process, GDL does not form covalent bonds with the surface of the cross-linked sodium polyacrylate. During the subsequent melt blending and spinning process, the small GDL molecules, due to their small molecular weight (178 Da), undergo severe migration and segregation in the polyester matrix, resulting in uneven distribution of the degradation agent in the fiber cross-section (the core concentration is only 30% of that on the surface). At the same time, without the protection of active particles, the cross-linked sodium polyacrylate nanoparticles undergo significant agglomeration during high-shear melt blending (SEM observation shows that the agglomerate particle size reaches 2-5 μm, much larger than the original particle size of 500 nm), leading to uncontrolled island phase size in the sea-island structure and a severe decrease in the uniformity of micro-nano channels. Test results show that the tensile strength of the fiber obtained in Comparative Example 2 is only 68% of that in Example 1 (2.8 cN / dtex vs 4.1 cN / dtex), and the degradation uniformity is poor (the standard deviation of the anaerobic degradation rate after 1288 days is ±15%, while that in Example 1 is ±3%). This proves that the mixing step is necessary to ensure the uniformity of PAAS dispersion and the uniformity of degradation agent distribution.

[0054] Test Example 1 - Micro / Nano Channel Expansion Rate Test Test principle: The method utilizes the property that cross-linked sodium polyacrylate absorbs water and swells when the ion concentration in sweat exceeds a threshold, driving the expansion of micro-nano channels. By comparing the average pore size change of micro-nano channels in the fiber cross section under dry and simulated sweat-soaked conditions, the channel expansion rate is calculated.

[0055] Test steps: (1) Sampling: Take 10cm long fiber samples from the fibers obtained in Examples 1-4 and Comparative Examples 1-2, with no less than 5 fibers in each group, and place them in a constant temperature and humidity chamber (20±2℃, 65±5%RH) for equilibration for 24h. (2) Dry state measurement: Take the equilibrated fiber samples, freeze them with liquid nitrogen and immediately observe the cross-sectional morphology of the fibers under a scanning electron microscope (SEM, accelerating voltage 5kV, magnification ×5000). Randomly select 20 micro-nano channels and measure the maximum inner diameter of each channel using image analysis software (ImageJ), and take the average value D0. (3) Preparation of simulated sweat: Prepare artificial sweat (containing 5g / L NaCl, 1g / L KCl, 0.5g / L Na2SO4, 1g / L urea, 1g / L lactic acid, and adjust the pH to 5.5±0.1 with NaOH) according to ISO 105-E04 standard. The total ion concentration of the simulated sweat is about 0.13mol / L. To simulate the sweating state during high-intensity exercise, a 5-fold concentrated simulated sweat solution was prepared (total ion concentration approximately 0.65 mol / L, exceeding the PAAS response threshold of 0.3 mol / L). (4) Wetting state measurement: The fiber sample was immersed in the above concentrated simulated sweat solution and kept in a constant temperature water bath at 37±1℃ for 30 min. After removal, excess liquid on the surface was removed with filter paper, and the SEM observation and measurement of step (2) were immediately repeated to obtain the average pore size D of the wetted state. (5) Calculation of channel expansion rate: Channel expansion rate (%) = (D-D0) / D0×100%. The channel expansion rate of the fiber in Example 1 in the concentrated simulated sweat solution was 415% (D0=120nm, D=618nm), while the channel expansion rate of Comparative Example 1 (rapid cooling process) was only 120%, proving the key role of step cooling in the formation of ordered micro-nano channels.

[0056] Test Example 2 - Fiber Tensile Strength Test Testing instrument: Single-fiber electronic tensile strength tester (range 0-20cN, accuracy 0.01cN). Testing standard: Refer to GB / T14337, clamping distance 20mm, tensile speed 20mm / min, pre-tension 0.05cN / dtex. Testing conditions: temperature 20±2℃, relative humidity 65±5%, no less than 50 valid data points for each sample group, and the average value is taken. Test Results: Example 1: Breaking strength 4.1 cN / dtex, elongation at break 32%, modulus 68 cN / dtex; Example 2: Breaking strength 3.8 cN / dtex, elongation at break 35%, modulus 62 cN / dtex; Example 3: Breaking strength 3.5 cN / dtex, elongation at break 28%, modulus 58 cN / dtex; Example 4: Breaking strength 2.9 cN / dtex, elongation at break 40%, modulus 45 cN / dtex; Comparative Example 1 (rapid cooling process): Breaking strength 3.2 cN / dtex, elongation at break 22%, modulus 55 cN / dtex; Comparative Example 2 (no internal mixing): Breaking strength 2.8 cN / dtex, elongation at break 18%, modulus 42 cN / dtex. The fiber strength of Comparative Example 2 was significantly lower than that of Example 1 (only 68%), verifying the necessity of the internal mixing step for ensuring uniform dispersion of crosslinked sodium polyacrylate and maintaining fiber mechanical properties. Comparative Example 1 showed a significant decrease in elongation at break due to uneven internal stress caused by rapid cooling (22% vs 32%).

[0057] Test Example 3 - Degradation Performance Test (a) Anaerobic landfill degradation test: Referring to ASTM D5511, under high-temperature anaerobic conditions (55±2℃), fiber samples (1g) were mixed with activated sludge and placed in a sealed bioreactor. Biogas production (CH4 and CO2) was monitored periodically, and the degradation rate was calculated based on the theoretical biogas production. Example 1 showed an anaerobic degradation rate of 62% after 1288 days (approximately 3.5 years) (predicted value based on an accelerated aging model). Comparative Example 2 (non-compacted, unevenly distributed degradation agent) showed a degradation rate of only 35% under the same conditions, with a large deviation (±15%). (b) Marine environment degradation test: Referring to ASTM D6691, tests were conducted in natural seawater (with added nutrients) at 30±1℃. Example 1 showed a degradation rate of 48% in a marine environment after 423 days. (c) Ecotoxicity test of degradation products: In accordance with ASTM E1963, plant growth tests (corn, beans) were conducted on the degradation residues. The germination rate and root length were not significantly different from the blank control group (p>0.05), which proves that the degradation products are environmentally friendly.

[0058] Test Example 4 - Moisture-wicking performance test (a) Vapor Height Test: Referring to FZ / T 01071, the fiber bundle was suspended vertically, with the lower end immersed in simulated sweat. After 30 minutes, the height of the liquid rising along the fiber was measured. The wicking height of Example 1 was 12.5 cm, and that of Comparative Example 1 (rapid cooling) was 7.2 cm. (b) Water Droplet Diffusion Time Test: Referring to AATCC TM 79, 0.1 mL of deionized water was dropped onto the surface of the fiber bundle, and the time required for the water droplet to completely diffuse was recorded. The diffusion time of Example 1 was 1.8 s, and that of Comparative Example 1 was 4.5 s. (c) Drying Rate Test: Referring to AATCC TM 201, the wetted fiber bundle (100% moisture content) was naturally dried in a standard environment (20°C, 65% RH), and the time required for the moisture content to drop to 10% was recorded. The drying time of Example 1 was 28 min, and that of Comparative Example 1 was 42 min. The above tests show that Example 1, due to its ordered micro-nano channel structure, has significantly better overall moisture absorption and perspiration performance than Comparative Example 1, which did not use a stepped cooling process.

[0059] Test Example 5 - Environmental Stability Test (a) Washability test: Referring to GB / T 12490-2014, the fiber was subjected to 50 accelerated washes, and the changes in channel expansion rate and tensile strength before and after washing were tested. After 50 washes, the channel expansion rate of Example 1 remained ≥92% (415%→382%), and the tensile strength remained ≥95% (4.1→3.9cN / dtex), demonstrating that the micro-nano channel structure and fiber mechanical properties have excellent washability stability. (b) UV aging test: Referring to ISO 4892-2, the fiber properties were tested after 100 hours of xenon lamp aging. The breaking strength of Example 1 after aging remained ≥88%. (c) Shelf life stability test: The fiber was stored in a standard environment (23±2℃, 50±5%RH) for 12 months, and samples were taken every 3 months to test the channel expansion rate and degradation performance. The results showed that the channel expansion rate did not decrease significantly within 12 months (fluctuation <5%), and the anaerobic degradation performance did not change significantly, meeting the shelf life requirements of commercial products.

[0060] The above conclusions demonstrate that the composite fiber provided in this application maintains high strength and comfort during its service life and achieves rapid environmental degradation during its disposal, exhibiting a high-performance, intelligent waste-degradation, and a green lifecycle. 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.

[0061] 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.

[0062] 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.

[0063] 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 its description. However, this disclosure method does not imply that the subject matter of this application requires more features than those mentioned in the claims. In fact, the embodiments have fewer features than all the features of the single embodiments disclosed above.

[0064] 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 composite fiber, characterized by, The composite fiber comprises: polyester, cross-linked sodium polyacrylate, and a degradation agent; wherein... The crosslinking density of the crosslinked sodium polyacrylate is 1.0 x 10 -4 -6.0 x 10 -4 mol / cm 3 , and the particle size is 200-800 nm. The polyester forms a continuous phase, and the cross-linked sodium polyacrylate forms a dispersed phase distributed within the continuous phase, together constituting the sea-island structure of the composite fiber.

2. The composite fiber according to claim 1, characterized by, The sea-island structure includes micro-nano channels; the micro-nano channels have a first pore size when the external ion concentration is below a predetermined concentration, and a second pore size when the concentration is not below the first concentration; the second pore size is at least 300% of the first pore size.

3. The composite fiber according to claim 1, characterized by, The difference in solubility parameters between the cross-linked sodium polyacrylate and the polyester is greater than 5 (J / cm³)^(1 / 2).

4. The composite fiber according to claim 3, characterized by The degrading agent has at least hydroxyl and lactone groups; the hydroxyl and lactone groups account for no less than 75% of the total number of functional groups in the degrading agent.

5. The conjugated fiber according to any one of claims 1 to 4, wherein The mass ratio of the polyester, the cross-linked sodium polyacrylate, and the degradation agent is (90.0-98.5): (1.0-7.0): (0.5-3.0).

6. A method for producing the composite fiber according to any one of claims 1 to 5, characterized by, The preparation method includes: S1. Provide polyester, cross-linked sodium polyacrylate and a degradation agent, pre-treat them and then melt-blend them to obtain a melt-spinning raw material; S2. Melt spinning is performed using the aforementioned melt spinning raw material, and the resulting nascent fibers are cooled in a stepped manner. S3. Post-process the cooled nascent fibers to obtain the composite fibers.

7. The preparation method according to claim 6, characterized in that, The preprocessing in S1 includes: The polyester, the cross-linked sodium polyacrylate, and the degradation agent are dried, and the dried cross-linked sodium polyacrylate and the degradation agent are then mixed to obtain active particles.

8. The preparation method according to claim 6, characterized in that, The stepped cooling in S2 includes passing the nascent fiber through a slow cooling zone, where the temperature range is 240℃-120℃ and the temperature gradient is 1-2℃ / cm.

9. The preparation method according to claim 6, characterized in that, The post-processing described in S3 includes stretching, shaping, and winding.

10. An article characterized in that, The article is made from the composite fiber as described in any one of claims 1-5 or the composite fiber obtained by any one of the preparation methods as described in claims 6-9.