Gap polymer-based composite fiber and preparation method thereof, and preparation method of cooling fabric

Abstract

The embodiment of the invention discloses a polymer-based composite fiber and a preparation method thereof, and a preparation method of a cooling fabric. The polymer-based composite fiber comprises a matrix, gaps and solid particles. The matrix includes one or more polymers, the plurality of voids are formed in the matrix, and each of the plurality of solid particles is disposed in a respective void of the plurality of voids. Each of the plurality of voids has a respective long axis, each long axis corresponding to a line extending through a longest dimension of the void, and each long axis extending in a direction parallel to a length of the substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 578,666, filed on August 25, 2023, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of radiant refrigeration, and more specifically, to a polymer-based composite fiber, a method for preparing the polymer-based composite fiber, and a method for preparing a refrigeration fabric. Background Art

[0004] Traditional textiles that provide personal cooling through active cooling techniques tend to be bulky, heavy, and expensive. For example, infrared-transparent textiles made of nanoporous polymer films have high transparency (about 90%) in the mid-infrared range, allowing heat to be radiated to the environment. However, due to the inherent trade-off between solar reflectivity and mid-infrared transparency, cooling below ambient temperature cannot be achieved by sunlight exposure during the day. In addition, solar-reflecting and infrared-emitting textiles require the addition of very high concentrations of ceramic nanoparticles, which increases the preparation cost and processing difficulty.

[0005] Therefore, there is still a need for a portable, efficient, and low-cost personal cooling strategy. Summary of the invention

[0006] In one embodiment, a polymer-based composite fiber includes a matrix (e.g., a continuous matrix) comprising one or more polymers; a plurality of voids formed in the continuous matrix; and a plurality of solid particles, each of the plurality of solid particles being disposed in a corresponding void in the plurality of voids; wherein each of the plurality of voids has a corresponding long axis, each long axis being a line extending through the longest dimension of the void; and each long axis extends in a direction parallel to the length of the matrix.

[0007] In one embodiment, each of the plurality of voids in the polymer-based composite fiber has an internal space, and each internal space is isolated from a surrounding environment.

[0008] In one embodiment, each void in the plurality of voids has a void interior surface, wherein each particle in the plurality of solid particles is completely encapsulated by the corresponding void interior surface.

[0009] In one embodiment, each void in the plurality of voids has an aspect ratio of at least 3, the aspect ratio being defined as the longest dimension of the corresponding void divided by the width of the void.

[0010] In one embodiment, for each respective void in the plurality of voids, a width of the void is less than or equal to an effective diameter of a solid particle disposed within the void.

[0011] In one embodiment, for each respective void, a solid particle is disposed in the void such that the solid particle divides the void into two separate sub-voids.

[0012] In one embodiment, the total volume of each void can be defined as the void volume plus the particle volume in the void. In one embodiment, the total volume of each void can be at least twice the volume of the corresponding particles in the void. In one embodiment, the total volume of each void can be at least three times the volume of the corresponding particles in the void. In one embodiment, the total volume of each void is less than 1000 times the volume of the corresponding particles in the void. In one embodiment, the total volume of each void is less than 100 times the volume of the corresponding particles in the void. In one embodiment, the total volume of each void is less than 50 times the volume of the corresponding particles in the void.

[0013] In one embodiment, the diameter of the polymer-based composite fiber is selected from the range of 100 nm (nanometer) to 1000 μm (micrometer). In one embodiment, the weight ratio of the plurality of particles of the polymer-based composite fiber to the weight of the continuous polymer matrix is ​​5% to 50%. In one embodiment, the weight ratio of the plurality of particles of the polymer-based composite fiber to the weight of the continuous polymer matrix is ​​5% to 65%.

[0014] In one embodiment, the porosity of the polymer-based composite fiber is in the range of 10% to 50%. In one embodiment, the porosity of the polymer-based composite fiber is in the range of 10% to 30%. In one embodiment, the porosity of the polymer-based composite fiber is in the range of 10% to 20%.

[0015] In one embodiment, the plurality of solid particles comprises a polyolefin, a mixture of ceramics, and / or metal oxide particles.

[0016] In one embodiment, the plurality of solid particles include polyolefin, aluminum oxide (Al2O3), silicon dioxide (SiO2), barium sulfate (BaSO4), zinc oxide (ZnO), boron nitride (BN), yttrium oxide (Y2O3), zirconium oxide (ZrO2), titanium dioxide (TiO2), zinc sulfide (ZnS), magnesium oxide (MgO) and / or ytterbium oxide (Yb2O3).

[0017] In one embodiment, the plurality of solid particles comprises polyolefin particles having an effective diameter in the range of 30 μm to 5000 μm.

[0018] In one embodiment, the plurality of solid particles comprises particles having an effective diameter in the range of 0.1 μm to 100 μm.

[0019] In one embodiment, the linear density of the polymer-based composite fiber is in the range of 1 d (denier) to 200 d, and the diameter of the polymer-based composite fiber is in the range of 10 μm to 1000 μm.

[0020] In one embodiment, the polymer-based composite fiber has an aspect ratio of at least 10, the aspect ratio being defined as the length of the polymer-based composite fiber divided by the diameter of the polymer-based composite fiber.

[0021] In one embodiment, the polymer-based composite fibers are part of a fabric.

[0022] In one embodiment, a method for preparing a solar-reflective polymer-based composite fiber includes: mixing a plurality of particles and a polymer material in a preset ratio to prepare a composite masterbatch; heating the composite masterbatch to melt the polymer material of the composite masterbatch to form a matrix, and at least some of the plurality of particles of the unmelted composite masterbatch are surrounded by the matrix to form a precursor composite fiber; and stretching the precursor composite fiber to form a solar-reflective polymer-based composite fiber, wherein stretching the precursor composite fiber includes: stretching the precursor composite fiber to form a plurality of voids in the solar-reflective polymer-based composite fiber through the plurality of particles surrounded by the matrix.

[0023] In one embodiment, the forming of the precursor composite fiber from the melted composite masterbatch comprises: forming the melted composite masterbatch into the precursor composite fiber by melt spinning. In one embodiment, the heating step comprises heating the polymer material to a temperature in the range of 100° C. to 400° C. In one embodiment, the stretching step comprises stretching the precursor composite fiber at a stretch ratio in the range of 2 to 6.

[0024] In one embodiment, the solar reflective polymer-based composite fiber has an aspect ratio of at least 10, where the aspect ratio is defined as the length of the solar reflective polymer-based composite fiber divided by the diameter of the solar reflective polymer-based composite fiber, wherein each of the multiple voids has a corresponding long axis, each long axis is a line extending through the longest dimension of the void; and each long axis extends in a direction parallel to the length of the matrix.

[0025] In one embodiment, a method for forming a cooling fabric includes: forming a plurality of solar-reflective polymer-based composite fibers; and weaving or knitting the solar-reflective polymer-based composite fibers into the cooling fabric, wherein forming a corresponding solar-reflective polymer-based composite fiber among the plurality of solar-reflective polymer-based composite fibers includes: mixing a plurality of particles and a polymer material in a preset proportion to prepare a composite masterbatch; heating the composite masterbatch to melt the polymer material of the composite masterbatch to form a matrix, while at least some of the plurality of particles of the unmelted composite masterbatch are surrounded by the matrix to form a precursor composite fiber; stretching the precursor composite fiber to form a solar-reflective polymer-based composite fiber, wherein stretching the precursor composite fiber includes: stretching the precursor composite fiber to form a plurality of voids in the solar-reflective polymer-based composite fiber through the plurality of particles surrounded by the matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Exemplary embodiments are shown in the reference figures of the accompanying drawings of the specification. The embodiments and drawings disclosed in the present application should be considered illustrative rather than restrictive.

[0027] Figure 1A Schematic diagram showing the forces (F) acting on particles within a polymer matrix within a fiber according to the present disclosure;

[0028] Figure 1B A schematic diagram showing the self-formed eye-shaped voids in the fiber disclosed in the present application;

[0029] Figure 1C A flow chart showing a method for preparing a solar reflective polymer-based composite fiber disclosed in the present application is shown;

[0030] Figure 1D A flow chart showing a method for preparing a cooling fabric disclosed in the present application is shown;

[0031] FIG. 2A to FIG. 2B The simulation of the void formation process is shown respectively, where Figure 2A is the fiber in its initial state, Figure 2B is the fiber after stretching, where the stretching ratio is about 2. As shown in the figure, voids are generated through the particles during the stretching process;

[0032] FIG. 3A to FIG. 3D The scattering efficiencies of particles, the whole of particles and voids, and voids obtained by FDTD (Finite Difference Time Domain, numerical simulation method) simulation are shown respectively, where Figure 3A-3C are the scattering efficiency spectra of particles, the whole of particles and voids, and the voids, respectively. Figure 3D is the average scattering efficiency of particles, particles and voids as a whole, and voids with a diameter (D) of 0.2 μm to 2 μm;

[0033] FIG. 4A to FIG. 4B Particles with diameters of 0.2 μm to 2 μm are shown respectively (eg Figure 4A as shown) and particles in the voids (as Figure 4B The scattering cross section in the wavelength range of 0.3 μm to 2.5 μm is shown;

[0034] FIG. 5A to FIG. 5B The SEM images of PET / BaSO4 fibers are shown respectively, Figure 5A is the SEM image of the fiber before stretching. Figure 5B is the SEM image of the stretched fiber;

[0035] FIG. 6A to FIG. 6D The elemental mapping of as-spun fibers is shown respectively, where Figure 6A-6D Element mappings corresponding to carbon (C), oxygen (O), barium (Ba), and sulfur (S);

[0036] FIG. 7A to FIG. 7B The tensile test of porous PET / BaSO4 yarn is shown respectively, where Fig. 7A The tensile test results of 10 PET / BaSO4 yarn samples are shown in Figure 2. Figure 7B Comparison of tensile test results of the yarn of the present application with commercial cotton and PET yarns;

[0037] Figure 8 The reflectance and emissivity spectra of PET / BaSO4 fabric in the UV-visible-infrared range are shown;

[0038] 9A to 9C The photo and schematic diagram of the radiation cooling test are shown respectively. Fig. 9A For photos of the test device, Fig. 9B Schematic diagram of cooling performance test below ambient temperature. Fig. 9C Schematic diagram of skin cooling performance test;

[0039] FIG. 10A to FIG. 10B The ambient temperature, PET / BaSO4 fabric temperature, solar radiation ( Fig. 10A ), relative humidity and wind speed ( Fig. 10B );

[0040] FIG. 11A to FIG. 11B The ambient temperature, PET / BaSO4 fabric temperature, solar radiation ( Fig.11A ), relative humidity and wind speed ( Fig. 11B );

[0041] FIG. 12A to FIG. 12BThe ambient temperature, PET / BaSO4 fabric temperature, cotton temperature, PET temperature, cellulose acetate temperature, flax temperature and solar radiation of the cooling performance test under full-day sunshine are shown respectively;

[0042] FIG. 13A to FIG. 13E PET / BaSO4( Fig.13A ),cotton( Fig. 13B ), cellulose acetate ( Fig. 13C )、PET( Fig.13D ) and flax ( Fig.13E ) at 800Wm -2 Thermal image of solar radiation (10 July 2023 at 15:00), with the mean apparent temperature marked in the centre of the image; and

[0043] Fig.14 The test results of the solar reflectance performance of the fibers disclosed in this application are shown for durability to washing, abrasion, bending and UV rays. DETAILED DESCRIPTION

[0044] Statement on Compounds and Nomenclature

[0045] In general, the terms and phrases used in this application have their art-recognized meanings, which can be found by reference to standard texts, journal references and contexts known to those skilled in the art. The following definitions are provided to clarify their specific use in the context of this application.

[0046] In one embodiment, the compositions or compounds of the present application, such as alloys or precursors to alloys, are isolated or substantially purified. In one embodiment, the isolated or purified compounds may be at least partially isolated or substantially purified as understood in the art. In one embodiment, the substantially purified compositions, compounds or preparations of the present application have a chemical purity of 95%; in one embodiment, optionally a chemical purity of 99%; in one embodiment, optionally a chemical purity of 99.9%; in one embodiment, optionally a chemical purity of 99.99%; and in one embodiment, optionally a chemical purity of 99.999%.

[0047] In the following description, many specific details of the device, device components and methods of the present application are set forth in order to thoroughly explain the inventive concept of the present application. However, it is obvious to those skilled in the art that the present application can be practiced without these specific details.

[0048] like Figure 1A-Figure 1DAs shown, the present application provides a polymer-based composite fiber 1000 having self-formed eye-shaped voids (hereinafter referred to as fiber 1000), a method 2000 for preparing a polymer-based composite fiber having self-formed eye-shaped voids reflecting sunlight, and a method 3000 for preparing a fabric using fiber 1000 for daytime passive radiation cooling.

[0049] like Figure 1B As shown, the fiber 1000 may include a matrix 100, a plurality of solid particles, and a plurality of voids. The matrix 100 may be a continuous matrix and contain one or more polymers. The matrix 100 may extend in the x direction. In other words, the matrix 100 may have a strip shape or a long needle shape, etc., which may have a length in the x direction. A plurality of voids are formed in the matrix 100, and each of the plurality of voids 300 may have an eye-shaped shape and may have a corresponding long axis x1, each long axis x1 being a line extending through the longest dimension of the void 300. Each long axis x1 extends in a length direction (x direction) parallel to the matrix 100. Each solid particle 200 (hereinafter referred to as particle 200) in the plurality of solid particles is disposed in a corresponding void 300 in the plurality of voids. It should be noted that the long axis of the void may also be understood as the maximum size in the space enclosed by the void.

[0050] The multiple voids in the fiber provided by the present application are formed by themselves during the stretching process, which will be described in detail below in conjunction with the accompanying drawings. Through the combination of the voids and the surrounding voids, the fiber has a high scattering efficiency and scattering cross-section within the solar wavelength range, which enables the fiber to effectively scatter sunlight. Therefore, the fabric formed by the fiber also has a high solar reflectivity, which can minimize the absorption of sunlight. In addition, the high reflectivity of the fiber is achieved by a low volume concentration of particulate additives, which can greatly reduce the preparation cost and processing difficulty of the radiation cooling fiber and fabric. In other words, the present application can provide a lightweight, efficient and low-cost fiber for personal cooling and a cooling fabric including the fiber.

[0051] Specifically, Figure 1A-1B As shown, when the tensile stress F of the particle 200 in the x-axis exceeds the weak van der Waals force f, the interface between the matrix 100 and the particle 200 separates and forms a void 300 around the particle 200. If the fiber 1000 is cooled under the tensile stress F described above, the porous structure inside the fiber 1000 can be preserved because the molecular chains of the matrix 100 are frozen in place and behave like solid glass again.

[0052] Optionally, each of the plurality of voids 300 in the fiber 1000 has an internal space, and each internal space can be isolated from the surrounding environment. In addition, each of the plurality of voids 300 can have a void internal surface, wherein each particle 200 of the plurality of solid particles or a particle cluster formed by some of the plurality of solid particles can be completely wrapped by the internal surface of the corresponding void 300.

[0053] The fiber 1000 includes a composite structure of a continuous polymer matrix 100, dispersed particles 200, and voids 300 associated with the particles 200, which can produce a larger scattering efficiency and scattering cross section within the solar wavelength range, so that the fiber can effectively scatter incident sunlight even at a low concentration of solid particle additives.

[0054] refer to Figure 1B and Figure 2B Alternatively, each void 300 in the plurality of voids may have an aspect ratio of at least 3, where the aspect ratio of the void may be defined as the longest dimension (long axis) of the corresponding void divided by the width of the void. Additionally, for each corresponding void 300 in the plurality of voids, the width of the void 300 may be less than or equal to the effective diameter of the particle 200 disposed within the void 300. Furthermore, the fiber 1000 may have an aspect ratio of at least 10, where the fiber aspect ratio may be defined as the length of the fiber divided by the diameter of the fiber.

[0055] For each respective void 300 , a particle 200 is disposed in the void 300 such that the particle 200 divides the void 300 into two separate sub-voids.

[0056] In some embodiments, the total volume of each void 300 may be defined as the void volume plus the particle volume in the void 300. In one embodiment, the total volume of each void 300 may be at least twice the volume of the corresponding particle 200 in the void 300. In one embodiment, the total volume of each void 300 may be at least three times the volume of the corresponding particle 200 in the void 300. In one embodiment, the total volume of each void 300 is less than 1000 times the volume of the corresponding particle 200 in the void 300. In one embodiment, the total volume of each void 300 is less than 100 times the volume of the corresponding particle 200 in the void 300. In one embodiment, the total volume of each void 300 is less than 50 times the volume of the corresponding particle 200 in the void 300. Therefore, the fiber formed by the particle additive with a low volume concentration can significantly reduce the preparation cost and processing difficulty of the radiative cooling fiber and fabric on the basis of achieving high reflectivity of the fiber.

[0057] In addition, in order to enhance the above-mentioned effects, the linear density of the fiber 1000 is in the range of 1d to 200d, and the diameter of the fiber 1000 is in the range of 10μm to 1000μm. For example, the diameter of the fiber 1000 can be selected in the range of 100nm to 1000μm. In some embodiments, the weight ratio of the plurality of particles of the fiber 1000 to the weight of the matrix 100 of the continuous polymer is 5% to 50%. In some embodiments, the weight ratio of the plurality of particles of the fiber 1000 to the weight of the matrix 100 is 5% to 65%.

[0058] In addition, to enhance the above effect, the porosity of the fiber 1000 is in the range of 10% to 50%. In one embodiment, the porosity of the fiber 1000 is in the range of 10% to 30%. In one embodiment, the porosity of the fiber 1000 is in the range of 10% to 20%.

[0059] Optionally, the size of the particles 200 is nanometer-scale. As an option, the particles 200 may include a mixture of polyolefins, ceramics and / or metal oxide particles. In other words, the particles 200 may be nano-polyolefin particles, nano-ceramic mixture particles and / or nano-metal oxide particles. Optionally, the particles 200 may include particles having an effective diameter in the range of 0.1 μm to 100 μm. For example, the particles 200 may include polyolefin particles having an effective diameter in the range of 30 μm to 5000 μm.

[0060] In some embodiments, the solid particles 200 may include polyolefins, aluminum oxide (Al2O3), silicon dioxide (SiO2), barium sulfate (BaSO4), zinc oxide (ZnO), boron nitride (BN), yttrium oxide (Y2O3), zirconium oxide (ZrO2), titanium dioxide (TiO2), zinc sulfide (ZnS), magnesium oxide (MgO) and / or ytterbium oxide (Yb2O3).

[0061] refer to Figure 1B-Figure 1D The preparation method 2000 of the fiber 1000 and the preparation method 3000 of the cooling fabric in the present application follow the industrial formation of commercial fibers. For example, the present application provides a porous structure fiber 1000 with particles in the voids formed by a melt spinning method. This method can be carried out on a large scale and is comparable to the current industrial process of textile fibers.

[0062] Specifically, the preparation method 3000 of the cooling fabric may include:

[0063] S1, forming a plurality of sunlight reflecting polymer-based composite fibers.

[0064] S2, weaving or knitting a plurality of solar reflective polymer-based composite fibers into a cooling fabric.

[0065] In the step S1 of forming a plurality of sunlight reflective polymer-based composite fibers, the method 2000 for preparing sunlight reflective polymer-based composite fibers may include:

[0066] S11, mixing a plurality of particles and a polymer material in a preset ratio to prepare a composite masterbatch.

[0067] S12, heating the composite masterbatch to melt the polymer material of the composite masterbatch to form a matrix, and at least some of the plurality of particles of the unmelted composite masterbatch are surrounded by the matrix to form a precursor composite fiber.

[0068] S13, stretching the precursor composite fiber to form a solar reflective polymer-based composite fiber, wherein stretching the precursor composite fiber includes: extending the precursor composite fiber to form a plurality of voids in the solar reflective polymer-based composite fiber through a plurality of particles surrounded by a matrix.

[0069] Optionally, the premixed masterbatch includes one or more polymers and a particulate (solid) additive. Prior to spinning, the mixture may be baked for more than 24 hours to completely remove moisture. In some embodiments of the present application, step S12 heating the composite masterbatch to melt the polymer material of the composite masterbatch without melting the plurality of particles of the composite masterbatch to form the matrix may include heating the polymer material to a temperature in the range of 100° C. to 400° C.

[0070] After the melt spinning and lubrication process, the partially oriented yarns with relatively low crystallinity and mechanical strength are collected on the cone. Generally speaking, the partially oriented yarns are not suitable for direct use in weaving or knitting. These partially oriented yarns can be stretched by differential rollers with heating functions to improve their crystallinity and mechanical strength, so that all the oriented yarns can be formed. After twisting, all the oriented yarns can be used to form fabrics through weaving or knitting. Optionally, step S14 stretches the precursor composite fiber 1000' (such as Figure 2A ) may include stretching the precursor composite fiber 1000' at a draw ratio in the range of 2 to 6.

[0071] During the stretching process of the fiber, voids can be formed around the solid particle additives. The composite structure of the fiber including a continuous polymer matrix, dispersed solid particles, and voids associated with the solid particles in the fiber can produce a large scattering efficiency and scattering cross section in the solar wavelength range, which allows the fiber to effectively scatter incident sunlight even at low concentrations of solid particle additives. Therefore, the prepared fabric can have high solar reflectivity and emissivity within the atmospheric window and achieve all-day passive radiative cooling.

[0072] Optionally, the solar reflective polymer-based composite fiber may have an aspect ratio of at least 10, which may be defined as the length of the solar reflective polymer-based composite fiber divided by the diameter of the solar reflective polymer-based composite fiber, wherein each of the plurality of voids may have a corresponding long axis, each long axis being a line extending through the longest dimension of the void, and each long axis may extend in a direction parallel to the length of the matrix. The preparation of the fibers disclosed in the present application may include spinning, drawing and twisting, and thereafter weaving or knitting for forming a fabric. The premixed masterbatch may include a polymer and a solid particulate additive. During the stretching process, the polymer will transition from a hard and relatively brittle glassy state to a viscous or rubbery state at a temperature above its glass transition temperature.

[0073] The pore forming process in the fiber preparation method provided in this application can be simulated by physical simulation software such as COMSOL. Figure 2A As shown, the particle 200 is placed at the center of the polymer-based composite fiber in the initial state, and the polymer-based composite fiber is solid in the initial state, wherein the polymer-based composite fiber in the initial state can be understood as the precursor composite fiber 1000'. Figure 2B As shown in FIG. 1 , after the precursor composite fiber 1000' is stretched, the interface between the matrix 100 and the particles 200 is separated and an eye-shaped porous structure is formed. Figure 3D As shown, the eye-shaped porous structure has greater scattering efficiency than the structure with only multiple voids.

[0074] In addition, if Figure 4A-4B As shown in FIG. 1 , due to the presence of voids, the scattering cross section of the eye-shaped porous structure is much larger than the scattering cross section of the structure with only a plurality of particles. Therefore, the fabric can strongly scatter the incident sunlight and has a high average reflectivity of sunlight, wherein the average reflectivity of sunlight (i.e., r 0.3-2.5μm ) is the reflectivity of the sample measured in the wavelength range of sunlight from 0.3 μm to 2.5 μm, and the result is obtained by weighted averaging with the AM1.5G solar spectrum, which is the standard spectrum on the surface of the earth. If the frequency of light matches the vibration frequency of chemical bonds, the light will experience strong resonant absorption. Most polymers used in fabrics have multiple chemical bonds that can emit mid-infrared radiation. Therefore, the fabrics disclosed in this application generally have high emissivity within the atmospheric window, where the emissivity (i.e., ) is the emissivity of the sample measured in the wavelength range of 8 μm to 13 μm, and the result obtained by weighted average with the 33°C black body radiation spectrum, 33°C can be understood as the human body temperature. Therefore, the high solar reflectivity and mid-infrared emissivity of the fabric in the present application enable it to achieve passive radiation cooling throughout the day.

[0075] Embodiment 1: Polyethylene terephthalate / Barium Sulfate (PET / BaSO4) porous fabric

[0076] The PET / BaSO4 porous fabric for all-day passive radiative cooling can be prepared according to the above method. The premixed masterbatch includes PET and ceramic nanoparticles. A PET / BaSO4 composite masterbatch with a BaSO4 concentration of 60% by weight (35% by volume) is prepared. The composite masterbatch includes PET in a mass ratio of 1 to 2. Before spinning, the mixture should be baked for more than 24 hours to completely remove moisture. Optionally, the polymer material in the premixed masterbatch is heated to a temperature in the range of 100°C to 400°C to form a matrix.

[0077] After melt spinning and lubrication process, partially oriented yarn with relatively low crystallinity and mechanical strength is collected on a cone. Generally speaking, partially oriented yarn is not suitable for direct use in weaving or knitting. This partially oriented yarn can be stretched by differential rollers with heating function to improve its crystallinity and mechanical strength. Optionally, this partially oriented yarn is stretched with a stretch ratio in the range of 2 to 6. After that, all oriented yarns can be formed. After twisting, the above-mentioned all oriented yarns can be used to form fabrics by weaving or knitting.

[0078] Density measurements of both spun fibers and drawn fibers can be based on the Archimedean principle. First, some cut fibers are weighed to obtain the mass. Next, the fibers are immersed in distilled water. Thus, the increase in volume of distilled water immersed in the fibers is obtained compared to distilled water alone, where the increase in volume is equal to the volume of immersed fibers. The density of these fibers can then be calculated. The densities of PET and BaSO4 are 1.38 gcm and 1.38 gcm, respectively. -3 and 4.5gcm -3 Therefore, the density of the spun fiber is calculated to be solid Should be 1.55gcm -3 , which is consistent with the measured value of 1.52 gcm -3 Very close. The measured density of the stretched fiber (ρ porous ) is 1.31 gcm -3 Therefore, the porosity φ of the stretched fiber can be calculated by the following formula (1) to be 15.6%.

[0079]

[0080] SEM images of melt-spun fibers Figure 5A-Figure 5B As shown, Figure 5A It shows that the core region and the surface of the fiber before stretching are solid. Figure 6A-6DThe EDS (Energy Dispersive X-ray Spectroscopy) elemental mapping shows that the BaSO4 nanoparticles are very uniformly dispersed in the fibers. Figure 5B It can be seen in Figure 5 that after the stretching process, the interface between the particles and the polymer matrix is ​​separated and the voids are generated by themselves.

[0081] like Figure 7A-7B As shown in the figure, 10 samples were subjected to tensile tests using a universal testing machine, and the tensile stress and elongation of most samples were very consistent with each other. The ultimate stress of PET / BaSO4 yarn is similar to that of commercial cotton or PET yarn. In addition, the elongation of the yarn formed according to the present application is close to that of PET yarn, which is much higher than that of cotton.

[0082] like Figure 8 As shown, due to the internal structure of the fiber including particles in the internal voids of the fiber, the solar reflectivity of the fabric made of the fiber is 92.0%, which is much higher than the solar reflectivity of commercial fabrics. The high reflectivity in the visible-infrared range is due to the large amount of scattering in the fiber during the stretching process and the increased scattering cross section. In the ultraviolet range, the reflectivity drops sharply in the UV-B band (i.e., 280nm-315nm). Due to the presence of π bonds in the benzene ring, most of the incident light in this band is absorbed by PET, and almost no light penetrates the fabric. This part of energy accounts for only about 0.07% of the total solar energy on the earth, so the absorbed heat is not a big problem. In addition, PET is widely used in the textile industry, and its UV resistance can meet the needs of textile use.

[0083] Use with Figure 9A-9C The same device 1 was field tested to evaluate the cooling performance of PET fabric. The test was conducted in summer (July 2023) in Hong Kong (22°16′50″N, 114°10′20″E), a tropical coastal city with a total precipitation (TPW) value of about 45 mm. The weather station 1-1 of device 1 can be used to monitor the ambient temperature, solar radiation intensity, relative humidity (RH) and wind speed near the sample in real time. T-type thermocouple 1-5 is attached to the back of fabric 1-4, and fabric 1-4 is placed on EPS (Expandablepolystyrene) foam 1-2. Optionally, the volume of EPS foam 1-2 can be 30×30×30cm 3 , density can be 25kgm -3 In addition, the device 1 may also include computer equipment 1-3 such as a laptop computer and data acquisition equipment 1-7.

[0084] like Fig. 10A As shown, at 700Wm -2 Under high solar radiation, cooling of more than 1°C below ambient temperature is achieved. Figure 10A-10B As shown in FIG. 1 , the fabric disclosed in the present application can achieve a cooling temperature ΔT of about 3.4°C relative to the ambient temperature during the day when the relative humidity is about 70% and the cloud cover is 40%. Because water vapor has strong infrared radiation and can block heat radiation to outer space, high relative humidity and cloud cover are obstacles to radiative cooling. For example, the cooling capacity under the condition of relative humidity of 70% and cloud cover of 40% is about 25% lower than the cooling capacity under the condition of sunny day (cloud cover of 10%). Figure 11A-11B As shown, at a relative humidity of about 85%, the fabric disclosed in the present application has a cooling temperature ΔT of about 4.5° C. at night. These results demonstrate that the fabric disclosed in the present application has excellent sub-ambient cooling performance even in weather conditions with high relative humidity values.

[0085] In addition, if Fig. 9C As shown, simulated human skin is used to evaluate the skin cooling performance of the fabric when it is worn as clothing. Simulated human skin 1-6 (r 0.3-2.5μm =0.38 and ε 8-13μm =0.95) has the same performance as real human skin (r 0.3-2.5μm =0.38 and ε 8-13μm =0.93) with very similar spectral characteristics. The input power of the silicone rubber heater was set to 100Wm -2 , to simulate the basal metabolic rate of the human body. Commercial fabrics (white) commonly used in summer clothing, such as PET fabric, cellulose acetate (CA) fabric, linen and cotton, were also tested as comparisons. During the test, the skin temperature of all samples was higher than the ambient temperature, because the heating power of the simulated skin far exceeded the cooling power in tropical climates, even for some high-performance radiative cooling films. During daytime measurements, white cotton had the lowest skin temperature among commercial fabrics due to its higher solar reflectivity. Compared with cotton fabric, the skin temperature of PET / BaSO4 fabric was 1.4℃ to 9.1℃ lower during the day.

[0086] like Figure 12A-12B As shown, the maximum cooling temperature ΔT occurs at noon, and the peak solar radiation is about 1050Wm -2According to the thermal image of the fabric tested at 15:00 on July 10, 2023, the apparent temperatures of cotton, CA and PET are close; the apparent temperature of PET / BaSO4 fabric is 4.8°C and 10.6°C lower than that of cotton and linen, respectively, which also verifies the excellent cooling performance of the fabric disclosed in this application (such as Figures 13A-13E At night, the cooling temperatures ΔT for all fabrics were within 0.4°C as they were very similar, with PET / BaSO4 having the highest temperature due to its relatively greater thickness resulting in better thermal insulation.

[0087] In addition, if Fig.14 As shown in the before and after tests, the solar reflectance of the fibers disclosed in the present application was tested for durability to washing, abrasion, bending, and UV exposure. The solar reflectance of the fibers disclosed in the present application did not substantially change when exposed to washing, abrasion, bending, or UV exposure. Therefore, the tests show that the solar reflectance of the fibers disclosed in the present application is highly durable to washing, abrasion, bending, and UV exposure.

[0088] Notices and Changes Regarding Incorporation by Reference

[0089] All references in this application, such as patent documents, including issued or granted patents or equivalents, patent application publications, and non-patent literature or other original materials, are hereby incorporated by reference in their entirety as if individually incorporated by reference, as long as each reference is at least partially inconsistent with the disclosure in this application (e.g., the partially inconsistent reference is incorporated by reference herein except for the partially inconsistent portion of the reference).

[0090] The terms and expressions used in this application are used as descriptive terms, rather than limiting terms, and the use of these terms and expressions is not intended to exclude any equivalents of the features shown and described or parts thereof, but it should be recognized that various modifications can be made within the scope of the invention claimed. Therefore, it should be understood that although the application has been specifically disclosed by preferred embodiments, exemplary embodiments and optional features, those skilled in the art can modify and change the concepts disclosed in the application, and these modifications and changes are considered to be within the scope of the invention defined in the appended claims. The specific embodiments provided in this application are examples of useful embodiments of the application, and those skilled in the art should understand that the application can be implemented using a large number of variants of the equipment, equipment components and method steps set forth in this specification. As apparent to those skilled in the art, the methods and equipment that can be used for this method may include a large number of optional compositions and processing elements and steps.

[0091] As used in this application and the appended claims, the singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise. In addition, the terms "a" (or "an"), "one or more", and "at least one" may be used interchangeably in this application. It should also be noted that the terms "including", "comprising", and "having" may be used interchangeably. The expression "any of claims XX-YY" (where XX and YY refer to claim numbers) is intended to provide multiple dependent claims in an alternative form and, in certain embodiments, may be interchangeable with the expression "any of claims XX-YY".

[0092] When the present application discloses a group of substituents, it is understood that all individual members and all subgroups of the group, including any isomers, enantiomers and diastereomers of the group members, are disclosed separately. When Markush groups or other groupings are used herein, all individual members of the group and all possible combinations and subcombinations of the group are intended to be included in the present application separately. When compounds are described herein, for example, no specific isomer, enantiomer or diastereomer of the compound is specified in the formula or chemical name, and the description is intended to include each isomer and enantiomer of the compound alone or in any combination. In addition, unless otherwise indicated, all isotopic variants of the compounds disclosed in the present application are intended to be covered by the present application. Isotopic variants of molecules can generally be used as standards for molecular determination and chemical and biological research related to molecules or their uses. Methods for preparing such isotopic variants are known in the art. The specific names of the compounds are only used as examples, because those skilled in the art can name the same compounds differently.

[0093] Unless otherwise stated, any device, system, formulation, composition of matter, or method described or exemplified in this application can be used to practice the present invention.

[0094] Whenever a range is given in the specification, such as a temperature range, a time range, or a composition or concentration range, all intermediate ranges and subranges and all individual values ​​contained in the given range should be included in the present application. It should be understood that any subrange or individual value in the range or subrange included in the description of the present application can be excluded from the claims of the present application.

[0095] All patents and publications mentioned in the specification are indicative of the skill level of the technicians in the field to which the invention belongs. The references cited in this application are all incorporated herein by reference to indicate the state of the art as of their publication or application date, and if necessary, this information can be used in this application to exclude specific embodiments in the prior art. For example, when claiming a composition of matter, it should be understood that compounds known and available in the art before the applicant's invention, including compounds for which authorization disclosure is provided in the references cited in this application, are not intended to be included in the composition of matter claims of this application.

[0096] As used in this application, "comprising" is synonymous with "including", "containing" or "characterized by", and is inclusive or open-ended and does not exclude other uncited elements or method steps. As used in this application, "comprising" does not include any elements, steps or ingredients not specified in the claim elements. As used in the application, "mainly composed of..." does not exclude materials or steps that do not substantially affect the basic and novel characteristics of the claim. In each case in this application, any of the terms "comprising", "substantially composed of" and "comprising" can be replaced with any of the other two terms. The invention illustratively described in this application can be appropriately practiced in the absence of any one or more elements, limitations not specifically disclosed in this application.

[0097] Those skilled in the art will appreciate that starting materials, biomaterials, reagents, synthesis methods, purification methods, analytical methods, assay methods and biomethods other than those shown in the specific embodiments may be used in the practice of the present application without excessive experimentation. All known functional equivalents of any such materials and methods are intended to be included in the present invention. The terms and expressions used are used as descriptive terms, rather than limiting terms, and are not intended to exclude any equivalents of the features and parts thereof when using these terms and expressions, but it should be recognized that various modifications can be made within the scope of the claimed invention. Therefore, it should be understood that although the present application has been specifically disclosed by preferred embodiments and optional features, those skilled in the art may modify and change the concepts disclosed in the present application, and these modifications and changes are considered to be within the scope of the present invention defined in the appended claims.

Claims

1. A polymer-based composite fiber, characterized in that: include: a matrix comprising one or more polymers; a plurality of voids formed in the matrix; as well as a plurality of solid particles, each of the plurality of solid particles being disposed in a corresponding void among the plurality of voids, wherein each of the plurality of voids has a respective long axis, each long axis corresponding to a line extending through the longest dimension of the void; as well as Each long axis extends in a direction parallel to the length of the substrate.

2. The polymer-based composite fiber according to claim 1, wherein Each of the plurality of voids has an inner space, Each interior space is isolated from the surrounding environment.

3. The polymer-based composite fiber according to claim 1, wherein Each of the plurality of voids has a void interior surface, Wherein, each of the plurality of solid particles is completely surrounded by the inner surface of the corresponding void.

4. The polymer-based composite fiber according to claim 1, wherein Each void of the plurality of voids has an aspect ratio of at least 3, the aspect ratio being defined as the longest dimension of the corresponding void divided by the width of the void.

5. The polymer-based composite fiber according to claim 4, wherein: For each respective void of the plurality of voids, a width of the void is less than or equal to an effective diameter of a solid particle disposed within the void.

6. The polymer-based composite fiber according to claim 5, wherein: For each corresponding void, the solid particles are disposed in the void such that the solid particles divide the void into two separate sub-voids.

7. The polymer-based composite fiber according to claim 1, wherein: The diameter of the polymer-based composite fiber is selected in the range of 100 nm to 1000 μm.

8. The polymer-based composite fiber according to claim 1, wherein The ratio of the weight of the plurality of solid particles in the polymer-based composite fiber to the weight of the matrix is ​​5% to 50%.

9. The polymer-based composite fiber according to claim 1, wherein: The polymer-based composite fiber has a porosity ranging from 10% to 50%.

10. The polymer-based composite fiber according to claim 1, wherein The plurality of solid particles include polyolefins, aluminum oxide (Al2O3), silicon dioxide (SiO2), barium sulfate (BaSO4), zinc oxide (ZnO), boron nitride (BN), yttrium oxide (Y2O3), zirconium oxide (ZrO2), titanium dioxide (TiO2), zinc sulfide (ZnS), magnesium oxide (MgO) and / or ytterbium oxide (Yb2O3).

11. The polymer-based composite fiber according to claim 1, wherein: The plurality of solid particles include polyolefin particles having an effective diameter in a range of 30 μm to 5000 μm.

12. The polymer-based composite fiber according to claim 1, wherein The plurality of solid particles include particles having an effective diameter in a range of 0.1 μm to 100 μm.

13. The polymer-based composite fiber according to claim 1, wherein: The linear density of the polymer-based composite fiber is in the range of 1 d to 200 d, and the diameter of the polymer-based composite fiber is in the range of 10 μm to 1000 μm.

14. The polymer-based composite fiber according to claim 1, wherein: The polymer-based composite fiber has an aspect ratio of at least 10, the aspect ratio being defined as the length of the polymer-based composite fiber divided by the diameter of the polymer-based composite fiber.

15. The polymer-based composite fiber according to claim 1, wherein: The polymer-based composite fibers are part of a fabric.

16. A method for preparing a sunlight-reflecting polymer-based composite fiber, characterized in that: The method comprises: mixing a plurality of particles and a polymer material in a predetermined ratio to prepare a composite masterbatch; heating the composite masterbatch to melt the polymer material of the composite masterbatch to form a matrix, and at least some of the plurality of particles of the composite masterbatch that are not melted are surrounded by the matrix to form a precursor composite fiber; and Stretching the precursor composite fiber to form the solar reflective polymer-based composite fiber, wherein stretching the precursor composite fiber comprises: The precursor composite fiber is elongated to form a plurality of voids in the solar reflective polymer-based composite fiber through a plurality of particles surrounded by the matrix.

17. The method according to claim 16, wherein: The step of forming the precursor composite fiber from the melted composite masterbatch includes: forming the precursor composite fiber from the melted composite masterbatch by melt spinning.

18. The method according to claim 16, wherein: Heating the composite masterbatch includes heating the polymer material to a temperature in a range of 100°C to 400°C.

19. The method according to claim 16, wherein: Stretching the precursor composite fiber further comprises stretching the precursor composite fiber at a draw ratio in a range of 2 to 6.

20. The method according to claim 16, wherein: The solar reflective polymer-based composite fiber has an aspect ratio of at least 10, wherein the aspect ratio is defined as the length of the solar reflective polymer-based composite fiber divided by the diameter of the solar reflective polymer-based composite fiber, wherein each of the plurality of voids has a respective long axis, each of the long axes being a line extending through the longest dimension of the void; and Each of the long axes extends in a direction parallel to the length of the substrate.

21. A method for preparing a cooling fabric, characterized in that: The method comprises: forming a plurality of solar reflective polymer-based composite fibers, wherein forming a respective solar reflective polymer-based composite fiber of the plurality of solar reflective polymer-based composite fibers comprises: mixing a plurality of particles and a polymer material in a predetermined ratio to prepare a composite masterbatch; heating the composite masterbatch to melt the polymer material of the composite masterbatch to form a matrix, and at least some of the plurality of particles of the composite masterbatch that are not melted are surrounded by the matrix to form a precursor composite fiber; stretching the precursor composite fiber to form the solar reflective polymer-based composite fiber; and weaving or knitting the plurality of solar reflective polymer-based composite fibers into the cooling fabric, Wherein, stretching the precursor composite fiber includes: extending the precursor composite fiber to form a plurality of voids in the solar reflective polymer-based composite fiber through a plurality of particles surrounded by the matrix.

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