A three-gradient structure one-way moisture-conducting nonwoven composite fabric and a preparation method thereof

Abstract

This invention discloses a triple-gradient unidirectional moisture-wicking nonwoven composite fabric and its preparation method, belonging to the field of clothing fabric technology. The nonwoven composite fabric comprises a needle-punched or spunlace composite hydrophobic fiber web layer, a fine fiber web diffusion layer, and a hydrophilic fiber web layer. The water contact angle of the hydrophobic fiber web layer, the fine fiber web diffusion layer, and the hydrophilic fiber web layer decreases sequentially, as does the fiber fineness. The fiber fineness in the hydrophobic fiber web layer is ≥2D. The porosity of the hydrophobic fiber web layer, the fine fiber web diffusion layer, and the hydrophilic fiber web layer decreases sequentially. The fibers in the hydrophobic and hydrophilic fiber web layers are mainly arranged along the output direction of the nonwoven machine, and the fine fiber web diffusion layer includes fibers arranged parallel and inclined to the output direction of the nonwoven machine. The nonwoven fabric of this invention can achieve rapid unidirectional moisture wicking and has the characteristics of good uniformity and softness characteristic of clothing fabrics.

Description

Technical Field

[0001] This invention belongs to the field of clothing fabric technology, and in particular relates to a triple gradient structure unidirectional moisture-wicking nonwoven composite fabric and its preparation method. Background Technology

[0002] The global fashion industry generates approximately $3 trillion in revenue annually, but simultaneously produces 20% of the world's wastewater (the second-largest water consumer globally) and 10% of global carbon emissions (exceeding the combined emissions of all international flights and shipping). Traditional garment fabric production processes are not environmentally friendly. Under the backdrop of "dual carbon" (carbon dioxide, carbon emissions, and water), the industry needs to adjust and improve its environmentally friendly production processes and transition towards healthier working environments. Nonwoven fabric production often replaces the previously complex processes of spinning, weaving, cutting, and sewing with needle-punching and hydroentangling techniques, directly web-forming fibers into nonwoven fabrics, simplifying the process of transforming raw materials into garment materials. Furthermore, it eliminates the need for traditional high-energy-consuming yarn manufacturing processes, using needle-punching and hydroentangling to connect fibers, thus reducing energy consumption. It is evident that nonwoven materials possess advantages such as a wide range of raw materials, short process flows, flexible and diverse processes, high production efficiency, numerous product varieties, and broad application areas. Therefore, these characteristics of nonwovens can be leveraged to apply nonwoven fabrics to the garment manufacturing field, making garment production more energy-efficient, less polluting, and sustainable.

[0003] Currently, the application of nonwoven apparel fabrics is limited both domestically and internationally, leaving a significant gap in the market. The few existing products have considerable limitations, such as causing stuffiness, lack of breathability, and pilling, or exhibiting stiffness similar to membranes or paper, resulting in garments lacking comfort. Ordinary clothing fabrics struggle to meet today's higher daily needs, leading to a surge in functional fabrics entering the market. For example, unidirectional moisture-wicking functional fabrics typically involve the rapid transfer of moisture and heat from the inner layer (skin contact layer) to the outer layer (air contact layer) for evaporation and drying, without the moisture and heat remaining in the inner layer. These fabrics do not stick to the skin, offering exceptional comfort and making them a preferred material for sportswear. However, most common moisture-wicking textiles use hydrophilic and hydrophobic chemical finishing agents on both sides of the fabric, which can easily cause environmental pollution.

[0004] Some water-wicking nonwoven materials typically utilize a double-layer hydrophilic and hydrophobic fiber web structure to create a wetting gradient effect, thereby achieving unidirectional moisture wicking. These existing technologies mainly reinforce the composite fiber web through multiple passes of hydroentangling or needle-punching nonwoven processes, and the fiber web before lamination is obtained only through parallel web laying. However, the aforementioned nonwoven processing methods are only suitable for preparing nonwoven composite materials for specific industries. Nonwoven materials prepared in this way are prone to pilling and fuzzing, have a stiff feel, and exhibit certain defects in mechanical properties. Due to the lack of mechanical and performance properties, they cannot be used for unidirectional moisture-wicking functional clothing fabrics. Summary of the Invention

[0005] In view of this, the present invention provides a triple gradient structure unidirectional moisture-wicking nonwoven composite fabric and its preparation method. The nonwoven composite fabric can not only achieve rapid unidirectional moisture wicking, but also has the characteristics of good uniformity and softness of clothing fabric.

[0006] This invention provides a triple gradient structure unidirectional moisture-wicking nonwoven composite fabric, comprising a needle-punched or spunlace composite hydrophobic fiber web layer, a fine fiber web diffusion layer, and a hydrophilic fiber web layer, wherein the water contact angle of the hydrophobic fiber web layer, the fine fiber web diffusion layer, and the hydrophilic fiber web layer decreases sequentially.

[0007] The fiber fineness in the hydrophobic fiber web layer, the fine fiber web diffusion layer, and the hydrophilic fiber web layer decreases sequentially; the fiber fineness in the hydrophobic fiber web layer is greater than 2D.

[0008] The porosity of the hydrophobic fiber web layer, the fine fiber web diffusion layer, and the hydrophilic fiber web layer decreases sequentially. The fibers in the hydrophobic and hydrophilic fiber web layers are mainly arranged along the output direction of the nonwoven machine. The fine fiber web diffusion layer includes fibers arranged parallel to and inclined to the output direction of the nonwoven machine. The areal density of the fine fiber web diffusion layer is less than 60 g / m². 2 .

[0009] The main principle of unidirectional moisture conduction is the difference in capillary pressure between the front and back fiber assemblies of the material. In other words, the two layers have different capillary water absorption capacities, resulting in different capillary wetting effects. The contact angle θ1 of the hydrophilic layer typically ranges from 0° to 90°, while the contact angle θ2 of the hydrophobic layer ranges from 90° to 180°. The capillary pressure difference formula is as follows:

[0010]

[0011] Where ΔP is the capillary pressure difference, P1 is the capillary pressure of the hydrophilic layer fiber assembly, P2 is the capillary pressure of the hydrophobic layer fiber assembly, and γ is the surface tension (when both capillaries are in the same liquid, their surface tensions are the same, i.e., γ1 = γ2 = γ). The equivalent radius of the capillary in the hydrophilic layer fiber assembly is given. The equivalent radius of the capillary in the hydrophobic layer fiber assembly is given.

[0012] It can be seen that the size of ΔP is not only controlled by the contact angle, but the fiber diameter is also a major influencing factor. The differential capillary effect model shows that the pore size of the fiber web is also an important factor affecting unidirectional moisture transport. Furthermore, when the contact angle difference is too large, even with one layer of hydrophilic fiber and one layer of hydrophobic fiber, the unidirectional moisture transport effect will still disappear. Therefore, relying solely on the wetting gradient (difference between hydrophilic and hydrophobic fiber materials) is too limiting for achieving unidirectional moisture transport. Thus, when one side is hydrophilic and the other hydrophobic, the fiber assembly with a hydrophilic-hydrophobic composite structure will generate a wetting gradient, i.e., a capillary pressure difference, forming a unidirectional moisture transport effect. Moreover, the finer the diameter of the hydrophilic layer fibers, the smaller the equivalent radius of the hydrophilic layer fiber web capillary; the coarser the diameter of the hydrophobic layer fibers, the larger the equivalent radius of the hydrophobic layer fiber web capillary. Therefore, the resulting capillary pressure difference is greater, meaning that due to changes in fiber diameter gradient and fiber web pore size gradient, a unidirectional moisture transport effect will also occur.

[0013] To overcome the shortcomings of existing technologies, this invention mainly prepares a nonwoven composite fabric with a three-layer structure of wetting gradient, pore size gradient and fiber diameter gradient by selecting fiber diameter and wettability, as well as controlling the overall structure and fiber web pore size. It has a rapid one-way moisture-wicking function and its mechanical properties fully meet the standards for apparel, and can be used as clothing fabric.

[0014] See details Figure 1 The fabric comprises a hydrophobic fiber web layer 1 (referred to as the hydrophobic layer or water-repellent layer), a fine fiber diffusion layer 2, and a hydrophilic fiber web layer 3 (referred to as the hydrophilic layer). The invention provides a unidirectional moisture-wicking nonwoven fabric with a triple-gradient structure, consisting of three layers: a hydrophobic fiber web layer 1 (referred to as the hydrophobic layer or water-repellent layer), a fine fiber diffusion layer 2, and a hydrophilic fiber web layer 3 (referred to as the hydrophilic layer). The hydrophobic fiber web layer 1 is composed of multiple relatively thick hydrophobic single fibers 4, the fine fiber diffusion layer 2 is composed of multiple relatively thin single fibers 5, and the hydrophilic fiber web layer 3 is composed of multiple relatively thin hydrophilic single fibers 6. The water contact angle of these three layers decreases sequentially. Figure 1 The data shows the differences in fiber fineness gradient and pore size gradient.

[0015] Furthermore, the fibers in both the hydrophobic fiber web layer 1 and the hydrophilic fiber web layer 3 are oriented along the output direction of the nonwoven machine; while the fibers in the fine fiber diffusion layer 2 are arranged parallel and inclined to the output direction of the nonwoven machine, and can be formed through cross-laying and multi-stage drafting, with the fibers in each thin fiber web layer arranged randomly. Further, due to the fiber interlayer transfer caused by the nonwoven reinforcement process, only the hydrophobic fibers are transferred, while the hydrophilic fibers are not transferred and no new hydrophilic channels are created. In addition, the nonwoven fabric mainly consists of chemical fibers and / or semi-chemical fibers, i.e., synthetic fibers and / or semi-synthetic fibers.

[0016] The fiber fineness in the hydrophobic fiber web is greater than 2D; preferably, the fiber material in the hydrophobic fiber web is polyolefin and / or polyester, such as polypropylene fiber (PP fiber), polyethylene terephthalate fiber (PET fiber), hydrophobic ES fiber, etc., with a contact angle greater than 105°.

[0017] Preferably, the fiber fineness in the hydrophilic fiber web layer is 0.4–0.6D, more preferably 0.4D; and / or, the hydrophilic fiber web layer is a hot-air bonded hydrophilic ES fiber web layer. In a preferred embodiment of the present invention, the fibers in the hydrophilic fiber web layer are all hydrophilic ES fibers with a fineness of 0.4D and a contact angle of 65–75°.

[0018] In embodiments of the present invention, the fiber fineness in the microfiber web diffusion layer can be between 0.4D and 2D. Preferably, the microfiber web diffusion layer is composed of island-island fibers after washing and opening (which may be called a microfiber diffusion layer); more preferably, it is formed by washing and opening WSPET / PA island-island fibers with a contact angle of 85-95°.

[0019] Denier (D) is a way of representing fiber fineness and belongs to the unit of linear density.

[0020] ES fiber is a type of chemical fiber with a core-sheath composite structure. Its sheath is PE (polyethylene), and its core is PET (polyester). Both hydrophilic and hydrophobic ES fibers have a core-sheath structure. The hydrophobic ES fiber mentioned above is 3D / 36mm with a contact angle of 125-130°, while the hydrophilic ES fiber is 0.4D / 36mm with a contact angle of 70-75°. (The difference in hydrophilicity and hydrophobicity of ES fibers is due to the addition of hydrophilic or hydrophobic masterbatches by upstream manufacturers during the preparation of chemical fiber masterbatches, which modifies the chemical fiber to give it these hydrophilic / hydrophobic properties.)

[0021] Island-island fiber is a composite fiber spun from a fiber-forming polymer dispersed in another fiber-forming polymer. In the fiber cross-section, the dispersed phase appears as "islands," while the matrix phase is analogous to the "sea." Viewed from the fiber's cross-section, it resembles a sea with many islands, where large molecules are finely dispersed and surrounded by other large molecules. WSPET / PA island-island fiber (WSPET-PA island-island fiber) has WSPET (water-soluble polyethylene terephthalate) as the matrix component and PA (polyamide, nylon) as the dispersed phase. After washing and fiber opening, some of the matrix phase dissolves, forming more entangled ultrafine fibers.

[0022] In an embodiment of the present invention, the hydrophobic fiber web layer 1, the fine fiber web diffusion layer 2, and the hydrophilic fiber web layer 3 are hydroentangled to form a nonwoven fabric as a whole.

[0023] In existing technologies, unidirectional moisture conduction only operates along the machine output (MD) direction on the horizontal plane. This results in water droplets, after penetrating the hydrophobic layer and reaching the intermediate mixing layer, only diffusing and wetting in one direction, leading to insufficient transport speed. Furthermore, existing technologies do not emphasize the impact of the needle / water needle insertion direction in needle punching / hydroentanglement processes on unidirectional moisture conduction. In contrast, the fine fiber diffusion layer in this application's embodiment can accelerate the unidirectional moisture transport rate, and the optimal process in hydroentanglement involves inserting the needle from the hydrophobic layer into the hydrophilic layer, achieving the fastest unidirectional moisture conduction effect.

[0024] Preferably, the areal density of the triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric is 80–150 g / m². 2 In some specific embodiments, due to the absence of sea components in the island fibers after washing and opening, and the fact that a small number of fibers are washed away by high-speed water jets during the hydroentangling process, the final areal density of the overall fabric is less than the sum of the densities of the three layers after carding.

[0025] The nonwoven composite fabric with a triple gradient structure provided in this invention has a unidirectional moisture-wicking function, such as... Figure 2 As shown, water droplets are rapidly transferred from the inner layer of the fabric (skin contact layer) through the microfiber diffusion layer to the outer layer of the fabric (air contact layer).

[0026] The technical solution of this application embodiment combines the effects of wetting gradient and differential capillary action. On the one hand, it is due to the pressure difference generated by the difference in water adsorption capacity, and on the other hand, it is due to the wicking pressure difference generated by adjusting the difference in the size of the fiber web pores. The two work together to make the unidirectional moisture wicking effect better. The application results in: the close-fitting water-repellent layer (hydrophobic fiber web layer) is drier and more comfortable, the middle microfiber diffusion layer (fine fiber web diffusion layer) has a shorter liquid penetration time and a faster moisture diffusion rate, and the entire fabric has a larger unidirectional transfer index.

[0027] Furthermore, in the preferred embodiment of the present invention, the mechanical properties of the island microfiber after water washing and opening are greatly improved without destroying the original fabric style of the microfiber, making it suitable for application in the field of clothing fabrics.

[0028] In a preferred embodiment of the present invention, the island-shaped microfiber layer after water-soluble fiber opening exhibits superior mechanical properties and moisture absorption characteristics compared to ordinary nonwoven materials. Specifically, island-shaped microfiber nonwoven materials prepared using the same process demonstrate better breaking strength and higher wicking height. Furthermore, in some embodiments, the outer layer of the fabric is an ultrafine ES fiber web, which, after hot air reinforcement, becomes softer and more comfortable. The coarser inner layer of ordinary water-repellent fibers provides support, resulting in a drier and more comfortable feel against the skin, meeting the requirements for wear.

[0029] Nonwoven webs undergoing nonwoven reinforcement methods such as high-frequency needle punching, high-density needle insertion, high-pressure water jetting, low-distance water jetting, or high-temperature, long-term hot-air bonding to generally improve their mechanical properties. However, there is also the possibility of damage to the material itself (e.g., the fibers within the web), resulting in a decrease in the overall mechanical properties of the web. Moreover, the fiber cohesion and entanglement generated solely by these nonwoven reinforcement methods are generally insufficient to meet the mechanical requirements of apparel fabrics. However, in this embodiment of the invention, the web, after being washed and opened, contains more entanglement of ultrafine fibers, significantly improving the overall mechanical properties of the fabric.

[0030] This invention provides a method for preparing a triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric as described above, comprising the following steps:

[0031] Hydrophobic fiber web material, fine fiber web material, and hydrophilic fiber web material are provided respectively, with the water contact angle, porosity, and fiber fineness decreasing sequentially among the three. The fiber fineness in the hydrophobic fiber web material is greater than 2D. In the hydrophobic and hydrophilic fiber web materials, the fibers are mainly arranged along the output direction of the nonwoven machine. The fine fiber web material includes fibers arranged parallel and inclined to the output direction of the nonwoven machine. The areal density of the fine fiber web material is less than 60 g / m³. 2

[0032] The hydrophobic fiber web material, the fine fiber web material, and the hydrophilic fiber web material are laid up in sequence to obtain a three-layer fiber web structure.

[0033] The three-layer fiber web is reinforced and composited by hydroentangling or needle punching to obtain a triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric.

[0034] See Figure 3 , Figure 3This is a schematic diagram of the process flow of a preferred embodiment of the present invention. The above-mentioned unidirectional moisture-wicking island microfiber nonwoven fabric with a triple-gradient structure is prepared by the following method steps:

[0035] Step 1: Select hydrophilic ES fibers, hydrophobic fibers, and water-soluble island fibers, and open and mix them separately. Preferably, select hydrophilic ES fibers with a fiber fineness of 0.4D, water-soluble island fibers with a fiber fineness of 0.8D, and select hydrophobic fibers with a fineness of ≥2D (can be 2D, 3D, or 4D) for the corresponding hydrophobic fiber web layer, such as PP fibers, PET fibers, and hydrophobic ES fibers.

[0036] More preferably, based on the three types of fibers with the selected diameters mentioned above, ES fibers with a contact angle of approximately 70°, WSPET / PA island fibers with a contact angle of approximately 90°, and hydrophobic fibers with a contact angle greater than 105° are selected. In a specific embodiment, hydrophobic PET fibers (3D), water-soluble island fibers (0.8D, PA being the island component), and hydrophilic core-sheath ES fibers (0.4D) are used; the hydrophobic PET fibers are ordinary PET fibers, with a standard moisture regain of generally 0.4%, the PA component can be PA6, and the hydrophilic layer can also be composed of other fibers with a fiber fineness of less than 0.6D and a contact angle of less than 75°. The cross-sections of each fiber are conventional, and commercially available products can be used.

[0037] Preferably, the preparation of the hydrophobic fiber web material includes: carding the hydrophobic fibers using a direct-lay method, so that the main fibers are laid parallel to each other along the output direction of the nonwoven machine to form a web with an areal density of 30-60 g / m². 2 Hydrophobic fiber mesh material.

[0038] Preferably, the preparation of the hydrophilic fiber web material includes: combing the hydrophilic ES fibers using a direct laying method, so that the main fibers are laid parallel to the output direction of the nonwoven machine, and then performing hot air heat bonding reinforcement to obtain the hydrophilic fiber web material (which can be a hot air hydrophilic ES nonwoven fabric).

[0039] Preferably, the preparation of the fine fiber web material includes:

[0040] WSPET-PA island fibers are carded using a vertical cross-laying method and then drawn to achieve an areal density of 30-60 g / m². 2 Island fiber netting;

[0041] The island fiber web is subjected to water-soluble weight reduction fiber opening to obtain PA island fine fiber web material (which can be PA conductive microfiber web).

[0042] Correspondingly, the second to fifth steps of the preparation method in the specific embodiments of the present invention are as follows:

[0043] Step 2: Feed the ES fibers and hydrophobic fibers selected in Step 1 into the carding machine separately, and card them using the direct-lay method. After carding, the ES fibers and hydrophobic fibers are laid parallel to each other along the output direction of the machine. The amount of fiber fed can be adjusted. The areal density of the resulting hydrophilic ES fiber web material is 30-60 g / m². 2 Specifically, it can be 30g / m 2 40g / m 2 50g / m 2 60g / m 2 The areal density of hydrophobic fiber webs (or simply hydrophobic fiber webs) is 30-60 g / m². 2 .

[0044] Step 3: Feed the WSPET-PA island-island fibers selected in Step 1 into a roller carding machine. A vertical cross-laying method is used, where the clamping curtain is held by a pulley and oscillates back and forth, causing the thin carded fiber web to move laterally back and forth on the forming curtain, thus laying it into a fiber web with a certain number of layers and thickness. The areal density of the fiber web can be adjusted by regulating the amplitude and speed of the clamping curtain's oscillation. After drafting, the areal density of the resulting island-island fiber web is 30-60 g / m². 2 .

[0045] In some embodiments of the present invention, the weight difference between the raw material feed and output during the carding process is caused by factors such as edge suction and short fiber fly, resulting in fiber quality loss. Therefore, a coefficient suitable for laboratory carding machines, derived through repeated experiments, is selected and must be included in the calculation of the fed fiber quality. In some embodiments, if ES fibers or ordinary PET fibers mentioned in the text are to be carded, the coefficient of 1.2 mentioned here for laboratory carding machines must be multiplied. For example, to prepare ES fibers with an areal density of 30-60 g / m², 36-72 g of ES fibers need to be fed. If island-of-the-sea fibers are to be carded, the coefficient must be multiplied by 1.6-1.7 because the dissolution from washing and opening must also be considered. Similarly, to prepare island-of-the-sea fibers with an areal density of 30 g / m² and to ensure a weight loss rate of more than 26%, 48-51 g of island-of-the-sea fibers need to be fed. In addition, the order of the second and third steps can be interchanged.

[0046] Step 4: Feed the hydrophilic ES fiber web formed in the parallel web laying step 2 into a double-web clamping hot air penetration oven for hot air bonding reinforcement, resulting in a hydrophilic ES hot air fabric. By adjusting the heat bonding temperature in the oven, the ES hot air fabric produced from the oven has a soft and comfortable feel.

[0047] Preferably, in the fourth step, the double meshes are fed into a hot air penetration oven under a clamping pressure of 10N. More preferably, the hot air thermal bonding and reinforcement time in the fourth step is selected to be 2-5 minutes.

[0048] And / or, hydrophobic PET fiber webs can be hydroentangled and reinforced. The pressure of the pre-hydroentangled water jet is adjusted to 25 bar, and the pressure of the main hydroentangled water jet is adjusted to 35 bar, 45 bar, and 55 bar. After continuous spraying and reinforcement by high-speed water jet, hydrophobic PET hydroentangled fabric is obtained.

[0049] Step 5: Feed the island fiber web formed by cross-laying in step 3 into the water washing and fiber opening device for water-soluble weight reduction fiber opening; the water temperature can be adjusted by gradient rise, and by controlling the water temperature step and the fiber web residence time, PA island ultrafine fiber webs with different degrees of fiber opening can be obtained, thereby obtaining PA island fiber webs with different pore sizes.

[0050] Preferably, the temperature range for opening the island-island fiber in the fifth step, where water solubility is reduced, is selected as 60–100℃ (around 25℃ has no effect on opening, and basically no opening occurs); more preferably, the dwell time of the fiber web during opening of the island-island fiber in the fifth step at different temperature ranges is 15–180s. Further, the weight loss rate of the PA island fine fiber web material is less than 30%, such as 0–26%. In some embodiments, the water washing and opening can be performed in multiple stages, for example, the fabric / island-island fiber web can be sequentially placed into a first constant temperature water bath (water temperature set at 60℃, dwell time 15–30s), a second constant temperature water bath (water temperature set at 80℃, dwell time 15–30s), and a third constant temperature water bath (water temperature set at 100℃, dwell time 1–2min). Furthermore, the order of the fourth and fifth steps can be interchanged.

[0051] In this embodiment of the invention, the hydrophobic fiber web material, fine fiber web material, and hydrophilic fiber web material prepared above are sequentially layered (arranged in the CD direction) to form a three-layer fiber web structure; then, hydroentangling or needle punching is performed to achieve reinforcement and composite bonding, followed by drying to obtain the triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric. The preferred specific steps are as follows:

[0052] Step 6: Lay the three materials together in the order of hydrophobic fiber web / PA island microfiber web / hydrophilic ES hot air cloth to obtain a "sandwich" structure fiber web.

[0053] Preferably, in the sixth step, the hydrophilic ES hot air fabric and the hydrophobic fiber web are laid directly into a web after carding, and the fibers in the web are oriented in the direction of machine output. In the sixth step, the fibers in each layer of the PA island fiber web are highly oriented, but the web after cross-laying and drawing process is randomly arranged.

[0054] Step 7: The obtained "sandwich" structure fiber web is reinforced and composited by multiple hydroentangling processes. By adjusting the hydroentangling pressure, hydroentangled nonwoven composite materials with different densities can be obtained. Then, conventional low-temperature drying (low-temperature drying, approximately 30-40℃) is performed to obtain a unidirectional moisture-wicking nonwoven fabric with a triple gradient structure (which can be referred to as a three-gradient unidirectional moisture-wicking fabric).

[0055] Alternatively, the obtained "sandwich" structure fiber web can be needle-punched for reinforcement. Specifically, the "sandwich" structure fiber web can be placed on the feed curtain of the needle punching machine, with the hydrophobic fiber web material facing the direction of the needle, ensuring that the needle is injected vertically from the hydrophobic layer into the hydrophilic layer. Preferably, the fiber web is pre-punched once and then needle-punched twice to obtain a unidirectional moisture-wicking nonwoven fabric with a triple gradient structure.

[0056] In some embodiments, the multi-stage hydroentangling reinforcement includes pre-hydroentangling and main hydroentangling; for example, the pre-hydroentangling water needle pressure can be adjusted to 25 bar, and the main hydroentangling water needle pressure can be adjusted to 45-65 bar, 65-85 bar, or 85-105 bar. The "sandwich structure fiber web" is placed on the feed curtain of the needle punching machine, with the hydrophobic layer facing the water needle direction, ensuring that the water jet is perpendicularly injected from the hydrophobic layer into the hydrophilic layer. Relying on high-pressure water, passing through the spray plate in the hydroentangling head, a fine high-pressure water needle jet is formed, continuously spraying the fiber web on the feed curtain. Under the dual action of the direct impact force of the water needle and the reflected water flow force, the fibers in the fiber web shift, interweave, and become entangled and bound together, forming numerous mechanical bonds, thereby reinforcing the fiber web.

[0057] In other specific embodiments, the pre-needling process parameters include: a needling frequency of 100 needles / min, a needling stroke of 60mm, and a single-needle-plate downward needling method; the main needling process parameters include: a first needling frequency of 300 needles / min, a second needling frequency of 500 needles / min, and a needling stroke of 60mm for both, both using a single-needle-plate downward needling method. As the needles penetrate the fiber web layer, the fibers become entangled during movement. Simultaneously, due to friction and the vertical displacement of the fibers, the fiber web is compressed, thus strengthening it.

[0058] Compared with existing technologies, the nonwoven composite fabric provided in this invention possesses a triple gradient of diameter, fiber web size, and wetting gradient, achieving excellent unidirectional moisture wicking effect. Furthermore, the microfiber diffusion layer employs a cross-laid web, allowing water droplets to diffuse simultaneously in two dimensions within the horizontal plane of the diffusion layer after moving from the hydrophobic layer to the microfiber diffusion layer. This uniformly reduces water droplet content and diffuses evenly towards the hydrophilic layer, resulting in a faster moisture wicking rate and better moisture wicking effect. This invention uses a nonwoven process to prepare clothing fabrics, offering advantages such as a short process flow, high production capacity, low cost, and no chemical additives. The resulting fabric can quickly wick moisture unidirectionally and also possesses the characteristics of good uniformity, breathability, softness, and flexibility.

[0059] Furthermore, this invention embodiment is based on a reinforced composite of three raw materials: island-island fiber, ES fiber, and hydrophobic fiber. The water-soluble island-island fiber used in the microfiber diffusion layer is more environmentally friendly in processing than the alkali-soluble island-island fiber used previously, and it can achieve stable and controllable fiber opening. The island component fibers after opening have better mechanical properties and moisture absorption characteristics. At the same time, after being reinforced by hot air, the ES fiber has a more delicate and soft feel, while also providing the fabric with a certain degree of elasticity. The hydrophobic fiber web layer with a larger fiber diameter serves as the support layer of the fabric, making it drier and more comfortable to wear, and also improving the overall tensile strength of the fabric. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the cross-sectional structure of the unidirectional moisture-wicking nonwoven composite fabric in an embodiment of the present invention.

[0061] Figure 2 This is a schematic diagram illustrating the unidirectional moisture-wicking function of the nonwoven composite fabric described in an embodiment of the present invention.

[0062] Figure 3 This is a schematic diagram of the process flow of a preferred embodiment of the present invention;

[0063] Figure 4 This is a graph showing the unidirectional moisture conduction performance test results of Embodiment 1 of the present invention;

[0064] Figure 5 This is a grading chart of the national standard dynamic moisture transfer test indicators. Detailed Implementation

[0065] The present invention will be further illustrated below with reference to specific embodiments, but these embodiments do not limit the invention in any way. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various modifications or alterations to the invention, and these equivalent forms also fall within the scope defined by the appended claims. The raw materials, methods, and equipment used in this invention are conventional in the art. Unless otherwise specified, the raw materials and equipment used in this embodiment are all commercially available and conventional in the art.

[0066] The sample testing methods include:

[0067] ①Mechanical property testing: YG026MB electronic fabric strength tester

[0068] The instrument is placed under standard atmospheric conditions with a temperature of 20℃±2℃ and a relative humidity of 65%±4%. Turn on the instrument and check its electronic components. Preheat the instrument for 10-15 minutes. Prepare five sets of samples with a width of 50mm (±0.5mm) and a length of 200mm (±0.5mm). Place one end of the fabric sample into the upper clamp, ensuring the fabric is fully clamped. Adjust the sample position to ensure it is vertical, then place the other end into the lower clamp, again ensuring it is clamped securely. Set the tensile speed to 100mm / min on the instrument's control panel and stretch until the sample breaks. Repeat the tensile test on all five sets of samples. After the test, record the breaking strength and elongation at break, and analyze the test data.

[0069] ②Moisture-wicking performance test:

[0070] M290 Liquid Moisture Analyzer (MMT)

[0071] Turn on the M290 liquid moisture analyzer and preheat the instrument for 15-30 minutes. Cut five circular samples with a diameter of approximately 100mm. Place the samples horizontally between the upper and lower concentric sensors of the instrument, ensuring close contact between the samples and sensors. Apply a fixing pressure using the fixing device to ensure the samples do not move during the test. Using the syringe or other injection device provided with the instrument, slowly and evenly inject 0.17g of standard test solution into the center of the sample on the side in contact with the skin, simulating the process of human sweating. Set the test parameters on the instrument's operation panel, such as test time and data acquisition frequency, and then start the test program. The instrument will start running automatically. The computer will dynamically record the resistance changes of the upper and lower sensors, monitor and collect various data of the samples during the test in real time (including surface / bottom layer wetting time, surface / bottom layer water absorption rate, surface / bottom layer maximum wetting radius, surface / bottom layer liquid moisture diffusion rate, cumulative unidirectional transfer capacity, and overall liquid moisture management capacity), and analyze the experimental data.

[0072] YG(B)871 Capillary Effect Measuring Instrument

[0073] Prepare the appropriate test solution according to the test requirements. Select five representative fabric samples. The samples should be flat, wrinkle-free, and undamaged, with a general size of 200mm × 25mm. Fix one end of the prepared sample to the instrument's crossbeam using a tension clamp, suspending the sample vertically above the water tank. Ensure the sample hangs naturally without twisting or bending. Slowly pour the preheated test solution to the specified temperature into the water tank, ensuring the bottom of the sample is submerged approximately 5-10mm. Set the temperature of the constant temperature bath and the test time using the instrument's control panel according to the test requirements. After confirming that the sample is correctly installed, the test solution height is appropriate, and the test parameters are set correctly, start the instrument to begin the test. During the test, observe the rise of the liquid on the sample surface. When the liquid reaches a stable height on the sample, record the height at which the liquid has risen and the corresponding test time, and analyze the experimental data.

[0074] Test methods for unidirectional moisture wicking performance: National Standard GB / T 21655.1-2023 Part 1: Unidirectional combined test method; National Standard GB / T 21655.2-2019 Evaluation of moisture absorption and quick-drying properties of textiles Part 2: Dynamic moisture transfer method

[0075] Example 1

[0076] like Figure 1 As shown, the triple-gradient unidirectional moisture-wicking nonwoven fabric of this embodiment consists of a hydrophobic layer, a hydrophilic layer, and a microfiber diffusion layer in the middle. The hydrophobic layer is entirely composed of hydrophobic fibers, the microfiber diffusion layer is entirely composed of WSPET / PA island fibers, and the hydrophilic layer is entirely composed of hydrophilic core-sheath ES fibers. The fibers in the hydrophobic and hydrophilic layers are arranged along the machine output direction, while the WSPET / PA island fibers in the microfiber diffusion layer are randomly arranged within the web after cross-laying and multi-stage drafting.

[0077] The technological process for the aforementioned triple-gradient unidirectional moisture-wicking nonwoven fabric is as follows: Figure 3 As shown, the preparation method and operation steps are as follows:

[0078] Step 1: Select hydrophobic fiber, WSPET / PA island fiber, and hydrophilic core-sheath ES fiber; the hydrophobic fiber is hydrophobic PET fiber (ordinary PET fiber) with a specification of 3D / 54mm, the WSPET / PA island fiber is WSPET / PA island microfiber with a specification of 19 islands, and the ES fiber is hydrophilic ES fiber (contact angle of 70-75°) with a specification of 0.4D / 36mm, and open and mix them separately.

[0079] Step 2: Feed the hydrophilic ES fibers and ordinary PET fibers selected in Step 1 into a carding machine, and card them using the direct-lay method. After carding, both are laid parallel to the machine direction to form a hydrophilic ES fiber web with an areal density of 30 g / m². 2 The contact angle is 74°; the surface density of ordinary PET fiber web is 30 g / m². 2 The contact angle is 106°.

[0080] Step 3: The WSPET-PA island-of-the-sea fibers selected in Step 1 are fed into a roller carding machine. A vertical cross-laying method is used, where the clamping curtain is held by a pulley and oscillates back and forth, causing the thin carded fiber web to move laterally back and forth on the forming curtain, thus laying it into a fiber web with a certain number of layers and thickness. The areal density of the fiber web is adjusted by regulating the amplitude and speed of the clamping curtain's oscillation. The areal density of the island-of-the-sea fiber web formed after drafting is 30 g / m². 2 .

[0081] Step 4: Feed the hydrophilic ES fiber web formed by parallel web laying in step 2 into a double-web clamping hot air penetration oven for hot air bonding and reinforcement. Adjust the oven temperature to 140℃ and dry for 3 minutes to obtain a hydrophilic ES hot air cloth.

[0082] Step 5: Feed the island fiber web formed by cross-laying in step 3 into the water washing and fiber opening device for water-soluble weight reduction fiber opening. Adjust the water washing and fiber opening conditions to 60℃ for 30s, 80℃ for 30s, and 100℃ for 1min to obtain PA island ultrafine fiber web with a weight loss rate of 26%.

[0083] Step 6: The three materials obtained are compounded in the order of hydrophilic ES hot air cloth / PA island microfiber mesh / hydrophobic PET fiber mesh to obtain a sandwich structure fiber mesh, wherein the fibers in the hydrophilic ES hot air cloth and the hydrophobic PET fiber mesh are oriented along the machine output direction.

[0084] Step 7: The obtained sandwich-structured fiber web is reinforced by hydroentangling. The pre-hydroentangling water needle pressure is adjusted to 25 bar, and the main hydroentangling water needle pressure is adjusted to 65 bar, 85 bar, and 105 bar. The hydrophobic layer is oriented towards the water needles to ensure that the water jet is injected vertically into the hydrophilic layer from the hydrophobic layer. Relying on high-pressure water, the water jets pass through the spray plate in the hydroentangling head to form fine high-pressure water needle jets, which continuously spray the fiber web on the drag net curtain. Under the dual action of the direct impact force of the water needles and the reflected water flow force, the fibers in the fiber web are displaced, interlaced, and entangled, forming numerous mechanical bonds, thereby reinforcing the fiber web. Then, it is dried at low temperature to obtain a unidirectional moisture-wicking nonwoven fabric with a triple gradient structure. For a schematic diagram of its unidirectional moisture-wicking function, please refer to [link to schematic diagram]. Figure 2 .

[0085] Example 2

[0086] The nonwoven fabric with a triple gradient structure and unidirectional moisture-wicking properties in this embodiment has the same fiber web layer structure as in Example 1.

[0087] The preparation method of the above-mentioned unidirectional moisture-wicking nonwoven fabric with triple gradient structure is as follows:

[0088] Step 1: Select hydrophobic fiber, WSPET / PA island fiber, and ES fiber. The hydrophobic fiber is a hydrophobic PET fiber with a specification of 3D / 54mm. The WSPET / PA island fiber is a WSPET / PA island microfiber with a specification of 19 islands. The ES fiber is a hydrophilic ES fiber with a specification of 0.4D / 36mm. Open and mix them separately.

[0089] Step 2: Feed the hydrophilic ES fibers and hydrophobic PET fibers selected in Step 1 into a carding machine, and card them using the direct-lay method. After carding, both are laid parallel to the machine direction, forming a hydrophilic ES fiber web with an areal density of 30 g / m². 2 The contact angle is 74°; the surface density of ordinary PET fiber web is 30 g / m². 2 The contact angle is 106°.

[0090] Step 3: The WSPET-PA island-of-the-sea fibers selected in Step 1 are fed into a roller carding machine. A vertical cross-laying method is used, where the clamping curtain is held by a pulley and oscillates back and forth, causing the thin carded fiber web to move laterally back and forth on the forming curtain, thus laying it into a fiber web with a certain number of layers and thickness. The areal density of the fiber web is adjusted by regulating the amplitude and speed of the clamping curtain's oscillation. The areal density of the island-of-the-sea fiber web formed after drafting is 30 g / m². 2 .

[0091] Step 4: Feed the hydrophilic ES fiber web formed by parallel web laying in step 2 into a double-web clamping hot air penetration oven for hot air bonding and reinforcement. Adjust the oven temperature to 140℃ and dry for 3 minutes to obtain a hydrophilic ES hot air cloth.

[0092] Step 5: The hydrophobic PET fiber web formed by parallel web laying in step 2 is reinforced by hydroentangling. The pressure of the pre-hydroentangling water needle is adjusted to 25 bar, and the pressure of the main hydroentangling water needle is adjusted to 35 bar, 45 bar, and 55 bar. After continuous spraying and reinforcement by high-speed water jet, a hydrophobic PET hydroentangled fabric is obtained.

[0093] Step 6: Feed the island fiber web formed by cross-laying in step 3 into the water washing and fiber opening device for water-soluble weight reduction fiber opening. Adjust the water washing and fiber opening conditions to 60℃ for 30s, 80℃ for 30s, and 100℃ for 1min to obtain PA island ultrafine fiber web with a weight loss rate of 26%.

[0094] Step 7: The three materials obtained are compounded in the order of hydrophilic ES hot air cloth / PA island microfiber mesh / hydrophobic PET spunlace cloth to obtain a sandwich structure mesh; wherein the hydrophilic ES hot air cloth and the hydrophobic PET spunlace cloth are both oriented in the direction of machine output.

[0095] Step 8: Hydroentangling reinforcement of the obtained sandwich-structured fiber web. Adjust the pre-hydroentangling water needle pressure to 25 bar, and the main hydroentangling water needle pressure to 45 bar, 65 bar, and 85 bar. Position the hydrophobic layer towards the water needles to ensure the water jet penetrates vertically into the hydrophilic layer. High-pressure water, passing through the spray plate in the hydroentangling head, forms a fine high-pressure water jet that continuously sprays the fiber web on the drag net curtain. Under the combined action of the direct impact of the water needles and the reflected water flow, the fibers in the web shift, interweave, and become entangled, forming numerous mechanical bonds, thus reinforcing the fiber web. Then, perform low-temperature drying to obtain a unidirectional moisture-wicking nonwoven fabric with a triple-gradient structure. Its unidirectional moisture-wicking function is illustrated below. Figure 2 As shown.

[0096] The wicking height and contact angle of the hydrophilic layer and microfiber diffusion layer materials in Example 1, the fabric sample in Example 1, and the hydrophobic layer material in Example 2 were tested respectively; the results are as follows.

[0097] Table 1. Core suction height results

[0098]

[0099] Figure 4 The graph shows the unidirectional moisture-wicking performance test results of Embodiment 1 of the present invention, corresponding to the data in Table 1. A wicking height ≥ 110 mm indicates excellent moisture absorption.

[0100] Example 3

[0101] The nonwoven fabric with a triple gradient structure and unidirectional moisture-wicking properties in this embodiment has the same fiber web layer structure as in Example 1.

[0102] The preparation method of the above-mentioned unidirectional moisture-wicking nonwoven fabric with triple gradient structure is as follows:

[0103] Step 1: Select hydrophobic fiber, WSPET / PA island fiber, and ES fiber. The hydrophobic fiber is hydrophobic PET fiber with a specification of 3D / 54mm. The WSPET / PA island fiber is WSPET / PA island microfiber with a specification of 19 islands. The ES fiber is hydrophilic ES fiber with a specification of 0.4D / 36mm. Open and mix them separately.

[0104] Step 2: Feed the hydrophilic ES fibers and ordinary PET fibers selected in Step 1 into a carding machine, and card them using the direct-lay method. After carding, both are laid parallel to the machine direction to form a hydrophilic ES fiber web with an areal density of 30 g / m². 2 The contact angle is 74°; the surface density of ordinary PET fiber web is 30 g / m². 2 The contact angle is 106°.

[0105] Step 3: The WSPET-PA island-of-the-sea fibers selected in Step 1 are fed into a roller carding machine. A vertical cross-laying method is used, where the clamping curtain is held by a pulley and oscillates back and forth, causing the thin carded fiber web to move laterally back and forth on the forming curtain, thus laying it into a fiber web with a certain number of layers and thickness. The areal density of the fiber web is adjusted by regulating the amplitude and speed of the clamping curtain's oscillation. The areal density of the island-of-the-sea fiber web formed after drafting is 30 g / m². 2 .

[0106] Step 4: Feed the hydrophilic ES fiber web formed by parallel web laying in step 2 into a double-web clamping hot air penetration oven for hot air bonding and reinforcement. Adjust the oven temperature to 140℃ and dry for 3 minutes to obtain a hydrophilic ES hot air cloth.

[0107] Step 5: Feed the island fiber web formed by cross-laying in step 3 into the water washing and fiber opening device, but do not perform hot water fiber opening. Adjust the water washing and fiber opening conditions to 25℃ and stay for 2 minutes to obtain PA island microfiber web (unopened) with a weight loss rate of 0%.

[0108] Step 6: The three materials obtained are compounded in the order of hydrophilic ES hot air cloth / PA island microfiber mesh / hydrophobic PET fiber mesh to obtain a sandwich structure fiber mesh, wherein the hydrophilic ES hot air cloth and hydrophobic PET fiber mesh are both oriented in the direction of machine output.

[0109] Step 7: Hydroentangling reinforcement of the obtained sandwich-structured fiber web. Adjust the pre-hydroentangling water needle pressure to 25 bar, and the main hydroentangling water needle pressure to 65 bar, 85 bar, and 105 bar. Position the hydrophobic layer towards the water needles to ensure the water jet penetrates vertically into the hydrophilic layer. High-pressure water, passing through the spray plate in the hydroentangling head, forms a fine high-pressure water jet that continuously sprays the fiber web on the drag net. Under the combined action of the direct impact of the water needles and the reflected water flow, the fibers in the web shift, interweave, and become entangled, forming numerous mechanical bonds, thus reinforcing the fiber web. Then, perform low-temperature drying to obtain a unidirectional moisture-wicking nonwoven fabric with a triple-gradient structure. Its unidirectional moisture-wicking function is illustrated below. Figure 2 As shown.

[0110] Example 4

[0111] The nonwoven fabric with a triple gradient structure and unidirectional moisture-wicking properties in this embodiment has the same fiber web layer structure as in Example 1.

[0112] The preparation method of the above-mentioned unidirectional moisture-wicking nonwoven fabric with triple gradient structure is as follows:

[0113] Step 1: Select hydrophobic fiber, WSPET / PA island fiber, and ES fiber; the hydrophobic fiber is hydrophobic PET fiber with a specification of 3D / 54mm, the WSPET / PA island fiber is WSPET / PA island microfiber with a specification of 19 islands, and the ES fiber is hydrophilic ES fiber with a specification of 0.4D / 36mm, and open and mix them separately.

[0114] Step 2: Feed the hydrophilic ES fibers and ordinary PET fibers selected in Step 1 into a carding machine, and card them using the direct-lay method. After carding, both are laid parallel to the machine direction (MD), forming a hydrophilic ES fiber web with an areal density of 30 g / m². 2 The contact angle is 74°; the surface density of ordinary PET fiber web is 60 g / m². 2 The contact angle is 106°.

[0115] Step 3: The WSPET-PA island-island fibers selected in Step 1 are fed into a roller carding machine. A vertical cross-laying method is used, where the clamping curtain is held by a pulley and oscillates back and forth, causing the thin carded fiber web to move laterally back and forth on the forming curtain, thus laying it into a fiber web with a certain number of layers and thickness. The areal density of the fiber web is adjusted by regulating the amplitude and speed of the clamping curtain's oscillation. The areal density of the island-island fiber web formed after drafting is 50 g / m². 2 .

[0116] Step 4: Feed the hydrophilic ES fiber web formed by parallel web laying in step 2 into a double-web clamping hot air penetration oven for hot air bonding and reinforcement. Adjust the oven temperature to 140℃ and dry for 3 minutes to obtain a hydrophilic ES hot air cloth.

[0117] Step 5: Feed the island fiber web formed by cross-laying in step 3 into the water washing and fiber opening device for water-soluble weight reduction fiber opening. Adjust the water washing and fiber opening conditions to 60℃ for 30s, 80℃ for 30s, and 100℃ for 1min30s to obtain PA island ultrafine fiber web with a weight loss rate of 26%.

[0118] Step 6: The three materials obtained are compounded in the order of hydrophilic ES hot air cloth / PA island microfiber mesh / hydrophobic PET fiber mesh to obtain a sandwich structure fiber mesh, wherein the hydrophilic ES hot air cloth and hydrophobic PET fiber mesh are both oriented in the direction of machine output.

[0119] Step 7: Needle-punching reinforcement of the obtained sandwich structure fiber web. Place the sandwich structure fiber web on the feeder of the needle punching machine, with the hydrophobic layer facing the direction of the needles, ensuring that the needles penetrate the hydrophilic layer perpendicularly from the hydrophobic layer. Perform one pre-needling and two main needle punches on the fiber web. The pre-needling process parameters are: needle punching frequency of 200 needles / min, needle punching stroke of 60mm, using a single-needle-plate downward needle punching method; the main needle punching process parameters are: the first needle punching frequency of 400 needles / min, the second needle punching frequency of 500 needles / min, both needle punching strokes of 60mm, both using a single-needle-plate downward needle punching method. As the needles pass through the fiber web layer, the fibers become entangled during movement. At the same time, due to the action of friction and the vertical displacement of the fibers, a certain amount of compression is generated on the fiber web, thus compressing the fiber web and reinforcing it, resulting in a unidirectional moisture-wicking nonwoven fabric with a triple-gradient structure. Its unidirectional moisture-wicking function is illustrated as follows: Figure 2 As shown.

[0120] Example 5

[0121] The nonwoven fabric with a triple gradient structure and unidirectional moisture-wicking properties in this embodiment has the same fiber web layer structure as in Example 1.

[0122] The preparation method of the above-mentioned unidirectional moisture-wicking nonwoven fabric with triple gradient structure is as follows:

[0123] Step 1: Select hydrophobic fiber, WSPET / PA island fiber, and ES fiber; the hydrophobic fiber is hydrophobic PET fiber with a specification of 3D / 54mm, the WSPET / PA island fiber is WSPET / PA island microfiber with a specification of 19 islands, and the ES fiber is hydrophilic ES fiber with a specification of 0.4D / 36mm, and open and mix them separately.

[0124] Step 2: Feed the hydrophilic ES fibers and ordinary PET fibers selected in Step 1 into a carding machine, and card them using the direct-lay method. After carding, both are laid parallel to the machine direction (MD), forming a hydrophilic ES fiber web with an areal density of 30 g / m². 2 The contact angle is 74°; the surface density of ordinary PET fiber web is 30 g / m². 2 The contact angle is 106°.

[0125] Step 3: The WSPET-PA island-island fibers selected in Step 1 are fed into a roller carding machine. A vertical cross-laying method is used, where the clamping curtain is held by a pulley and oscillates back and forth, causing the thin carded fiber web to move laterally back and forth on the forming curtain, thus laying it into a fiber web with a certain number of layers and thickness. The areal density of the fiber web is adjusted by regulating the amplitude and speed of the clamping curtain's oscillation. The areal density of the island-island fiber web formed after drafting is 90 g / m². 2 .

[0126] Step 4: Feed the island fiber web formed by cross-laying in step 3 into the water washing and fiber opening device for water-soluble weight reduction fiber opening. Adjust the water washing and fiber opening conditions to 60℃ for 15s, 80℃ for 15s, and 100℃ for 2min to obtain PA island ultrafine fiber web with a weight loss rate of 26%.

[0127] Step 5: The three materials obtained are compounded in the order of hydrophilic ES fiber mesh - PA island microfiber mesh - hydrophobic PET fiber mesh to obtain a sandwich structure fiber mesh, wherein the hydrophilic ES fiber mesh and the hydrophobic PET fiber mesh are both oriented in the direction of machine output.

[0128] Step 6: Hydroentangling reinforcement of the obtained sandwich-structured fiber web. Adjust the pre-hydroentangling water needle pressure to 25 bar, and adjust the main hydroentangling water needle pressure to 65 bar, 95 bar, and 115 bar. Position the hydrophobic layer towards the water needles to ensure the water jet is perpendicularly injected into the hydrophilic layer. High-pressure water, passing through the spray plate in the hydroentangling head, forms a fine high-pressure water jet that continuously sprays the fiber web on the drag net. Under the combined action of the direct impact of the water needles and the reflected water flow, the fibers in the web shift, interweave, and become entangled, forming numerous mechanical bonds, thus reinforcing the fiber web. Then, perform low-temperature drying to obtain a unidirectional moisture-wicking nonwoven fabric with a triple-gradient structure. Its unidirectional moisture-wicking function is illustrated in the diagram below. Figure 2 As shown.

[0129] The following are the results of MMT testing, breathability, and mechanical properties:

[0130] Table 2. MMT Test (Liquid Moisture Management Test) Examples

[0131]

[0132] During MMT testing, the surface layer is hydrophobic, and the bottom layer is hydrophilic. The data for the hydrophobic layer in the table is for calculating the unidirectional moisture conductivity index; analysis of the bottom layer, i.e., the hydrophilic layer, is sufficient.

[0133] Figure 5This is a performance index classification based on the dynamic moisture transfer method test. The unidirectional moisture-wicking index of all five examples is >700% >300% (level 5), with Example 1 achieving a moisture-wicking index of 1073, demonstrating excellent unidirectional moisture-wicking effect. The wetting time of the hydrophilic surface of Examples 1, 2, 3, and 5 is ≤3s (level 5); the water absorption rate of the hydrophilic surface of Examples 1, 2, 3, 4, and 5 is 50.1-100 (level 4); the maximum wetting radius of the hydrophilic surface of Examples 1, 2, 4, and 5 is 17.1-22 (level 4); and the liquid moisture diffusion rate of the hydrophilic surface of Examples 1, 2, 3, 4, and 5 is ≥4 (level 5). All these indicate that the hydrophilic surface has excellent moisture absorption capacity, rapidly wicking away sweat from the skin-contacting surface of the fabric and absorbing it into the hydrophilic surface, ensuring the skin remains cool and dry. Example 4 has the highest weight and the thickest thickness. It was prepared by needle punching process with only two main needle punches, resulting in a relatively loose structure. Its hydrophilic surface has a slightly poorer wetting time, but it is still between 3.1 and 4.0 (level 4). Its hydrophilic surface also has good moisture absorption capacity.

[0134] Table 3 shows the air permeability test results of the examples.

[0135] Serial Number Test fabric <![CDATA[Air permeability / mm·s -1 > ① Example 1 756.68 ② Example 2 830.36 ③ Example 3 1288.93 ④ Example 4 563.29 ⑤ Example 5 626.33 ⑥ hydrophobic layer 5310.34 ⑦ superfiber diffusion layer 1249.80 ⑧ hydrophilic layer 1476.59

[0136] Currently, there are no explicit requirements for many clothing products. Some knitted / woven fabrics require a breathability of ≥300mm / s. All five examples meet the requirements, and the higher the breathability, the better the breathability, resulting in a drier and more comfortable wearing experience. Among them, examples 4-5 have slightly lower breathability due to their larger weight and thicker fabric, but they still meet the ≥300mm / s requirement.

[0137] Table 4 shows the mechanical performance test results of the embodiments.

[0138] Example 1 Example 2 Example 3 Example 4 Example 5 Fracture strength / N 134.8 106.8 50.3 148.3 161.2 Elongation at break % 61.2％ 63.9％ 69.7％ 92.4％ 70.9％

[0139] Currently, the tensile strength range of nonwoven materials is mostly between 10-300N, including low-weight (30-80g / m²) products such as hygiene products (e.g., wet wipes, cotton pads). 2 The breaking strength of spunlace products may be 5-20N, such as medical dressings and industrial wiping cloths with higher basis weights (100-200g / m²). 2 The breaking strength of spunlace products is 20-100N.

[0140] The product weight in Examples 1-3 is 90 g / m³. 2 Compared with nonwoven products of the same weight and process, its mechanical properties have been significantly improved, with a breaking strength of up to 134.8 N, which can meet some performance requirements. Examples 4-5 increase the product weight to 150 g / m². 2 After being moved to the left and right sides, its mechanical properties are further improved, with a breaking strength of over 150N, which is sufficient to meet general wear performance requirements.

[0141] As can be seen from the above embodiments, the present invention provides a triple-gradient structure unidirectional moisture-wicking water-soluble island microfiber nonwoven composite fabric, as well as its preparation method and application. The unidirectional moisture-wicking nonwoven fabric comprises a hydrophilic layer, a microfiber diffusion layer, and a hydrophobic layer. By selecting fiber diameter and wettability, and through water-soluble weight reduction fiber opening processes, the pore size of the fiber web is controlled, thereby obtaining a nonwoven fabric with a three-layer structure possessing wetting gradient, pore size gradient, and fiber diameter gradient, and exhibiting rapid unidirectional moisture wicking function. Furthermore, for the microfiber diffusion layer, the island fibers, after being washed and opened, possess better mechanical properties and moisture absorption characteristics; the hydrophilic layer, with its ultrafine ES fiber web, is reinforced by hot air bonding, resulting in a more delicate and soft feel with a certain degree of elasticity; and the selection of coarser hydrophobic fibers as the hydrophobic layer in contact with the skin keeps the skin dry and comfortable, while also providing overall support for the fabric. The preparation process of this invention has the advantages of short process, high production capacity, low cost and no chemical additives. The resulting nonwoven fabric can achieve rapid unidirectional moisture wicking and has the characteristics of clothing fabric with good uniformity, breathability, softness and flexibility, which is conducive to its application in clothing and apparel.

[0142] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric, characterized in that, It includes a hydrophobic fiber web layer, a fine fiber web diffusion layer, and a hydrophilic fiber web layer, which are composed of needle-punched or hydroentangled composites, wherein the water contact angle of the hydrophobic fiber web layer, the fine fiber web diffusion layer, and the hydrophilic fiber web layer decreases sequentially. The fiber fineness in the hydrophobic fiber web layer, the fine fiber web diffusion layer, and the hydrophilic fiber web layer decreases sequentially; the fiber fineness in the hydrophobic fiber web layer is greater than 2D. The porosity of the hydrophobic fiber web layer, the fine fiber web diffusion layer, and the hydrophilic fiber web layer decreases sequentially. The fibers in the hydrophobic and hydrophilic fiber web layers are mainly arranged along the output direction of the nonwoven machine. The fibers in the hydrophobic fiber web layer are made of polyolefin and / or polyester. The fine fiber web diffusion layer includes fibers arranged parallel and inclined to the output direction of the nonwoven machine, and the areal density of the fine fiber web diffusion layer is less than 60 g / m². 2 The fine fiber web diffusion layer is formed by combing island fibers into a web and then washing and opening the fibers. The areal density of the triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric is 80~150 g / m². 2 .

2. The triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric according to claim 1, characterized in that, The fiber fineness in the hydrophilic fiber web is 0.4~0.6D, and / or the hydrophilic fiber web is a hot-air bonded hydrophilic ES fiber web.

3. A method for preparing a triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric according to any one of claims 1-2, comprising the following steps: Hydrophobic fiber web material, fine fiber web material, and hydrophilic fiber web material are provided respectively, with the water contact angle, porosity, and fiber fineness decreasing sequentially among the three. The fiber fineness in the hydrophobic fiber web material is greater than 2D. In the hydrophobic and hydrophilic fiber web materials, the fibers are mainly arranged along the output direction of the nonwoven machine. The fine fiber web material includes fibers arranged parallel and inclined to the output direction of the nonwoven machine. The areal density of the fine fiber web material is less than 60 g / m³. 2 ; The hydrophobic fiber web material, the fine fiber web material, and the hydrophilic fiber web material are laid up in sequence to obtain a three-layer fiber web structure. The three-layer fiber web is reinforced and composited by hydroentangling or needle punching to obtain a triple-gradient structure unidirectional moisture-wicking nonwoven composite fabric.

4. The preparation method according to claim 3, characterized in that, The preparation of the hydrophobic fiber web material includes: carding the hydrophobic fibers using a direct-laying method, so that the main fibers are laid parallel to the output direction of the nonwoven machine to form a web with an areal density of 30-60 g / m². 2 Hydrophobic fiber mesh material.

5. The preparation method according to claim 4, characterized in that, The preparation of the hydrophilic fiber web material includes: combing the hydrophilic ES fibers using a direct laying method, so that the main fibers are laid parallel to the output direction of the nonwoven machine, and then hot air bonding is used for reinforcement to obtain the hydrophilic fiber web material.

6. The preparation method according to any one of claims 3-5, characterized in that, The preparation of the fine fiber web material includes: WSPET-PA island fibers are carded using a vertical cross-laying method and then drawn to achieve an areal density of 30-60 g / m². 2 Island fiber netting; The island fiber web is subjected to water-soluble weight reduction fiber opening to obtain PA island fine fiber web material.

7. The preparation method according to claim 6, characterized in that, The water-soluble weight-reducing fiber opening temperature is 60~100℃, and the time is 15~180s; the weight loss rate of the PA island fine fiber web material is less than 30%.

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