Uhmwpe phase change energy storage fiber with skin-core structure and preparation method thereof

Abstract

This invention discloses a UHMWPE phase change energy storage fiber with a core-sheath structure and its preparation method. The phase change energy storage fiber includes a core layer and a sheath layer arranged coaxially. The core layer is supported by a three-dimensional porous skeleton, within which phase change energy storage material is distributed. The sheath layer is supported by a three-dimensional porous skeleton. Both the core and sheath three-dimensional porous skeletons are made of UHMWPE, with the density of the sheath three-dimensional porous skeleton being greater than that of the core, resulting in a dense structure. The preparation method involves first mixing raw materials according to a specified ratio and extruding them into precursor fibers; then subjecting them to super-stretching and heat setting treatments to form primary phase change energy storage fibers; finally, surface extraction and drying are performed to remove the phase change energy storage material from the surface layer, resulting in the UHMWPE phase change energy storage fiber with a dense sheath structure. The fiber structure of this invention is simple and features high strength, high latent heat value, low leakage rate, and high thermal energy conversion efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polymer processing forming technology, in particular to a UHMWPE (Ultra-high Molecular Weight Polyethylene Fiber) phase change energy storage fiber with a skin-core structure and a preparation method thereof. BACKGROUND

[0002] Intelligent temperature regulating textile (ITRT) combines phase change heat storage technology, spinning technology and textile weaving technology, and is the most widely studied intelligent temperature regulating material. The temperature regulating principle of ITRT is to use the reversible phase change of the contained phase change material with the change of the external environment temperature, that is, when the environment temperature rises, the phase change material absorbs and stores heat, and when the temperature decreases, the phase change material releases the stored heat, so as to realize the temperature self-regulation of the textile and create a "microclimate" environment with relatively constant temperature, so that the human body is always in a comfortable temperature range.

[0003] Phase Change Energy Storage Fiber (PCF) is the basic unit for preparing ITRT. At present, the commonly used preparation methods of PCF mainly include microcapsule spinning method, electrospinning method, hollow fiber filling method and composite spinning method. The microcapsule spinning method has realized industrialized production. Outlast Company cooperates with Germany TITRP to develop cellulose PCF prepared by solvent method, and the enthalpy of the PCF can reach 60 J / g. However, the product and its preparation process still have some shortcomings, such as complicated preparation process, low loading capacity of phase change microcapsules and general mechanical properties. In recent years, the electrospinning method has developed rapidly, but it has not realized industrialization. The problems such as electrical safety, low production efficiency and unstable structure need to be solved. The hollow fiber method needs to prepare hollow fibers first, and then immerse the phase change material in the hollow fibers. The process of this method is relatively complex, and the repeated wear and tear of the skin layer of the hollow fiber will cause a large amount of leakage of the phase change material during use. The composite spinning method refers to mixing the phase change energy storage material with the polymer matrix material to prepare a uniform blend or spinning solution, and then preparing PCF by melt spinning or solution spinning method. This method has the simplest preparation process and low cost, but it is difficult to balance high enthalpy and low leakage rate. The reason is that the commonly used polymer matrix, such as high-density polyethylene, polyurethane elastomer and ethylene-propylene-diene rubber, cannot form a complete and stable porous network to coat the phase change energy storage material with a small amount of polymer matrix. The amount of polymer material generally needs to be at least 30 parts or more by mass fraction, which causes the phase change energy storage material that can be carried to be relatively small, thereby affecting the performance of the final product. In addition, the energy storage phase change fibers prepared by the existing research are difficult to have the advantages of high strength, high phase change material loading capacity, low leakage rate, simple preparation, high heat response rate and the like. Therefore, it is necessary to develop a phase change energy storage fiber with more optimized performance to meet the market demand. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a UHMWPE phase change energy storage fiber with a skin-core structure, which has the characteristics of simple structure, high strength, high latent heat value, low leakage rate and high thermal energy conversion efficiency.

[0005] Another object of the present application is to provide a preparation method of the above-mentioned UHMWPE phase change energy storage fiber with a skin-core structure, which can realize large-scale and efficient continuous production of the UHMWPE phase change energy storage fiber, has high production efficiency and low production cost.

[0006] The technical solution of the present invention is as follows: a UHMWPE phase change energy storage fiber with a core-sheath structure, comprising a core layer and a sheath layer coaxially arranged, wherein the supporting body of the core layer is a three-dimensional porous skeleton, and phase change energy storage material is distributed in the three-dimensional channels of the three-dimensional porous skeleton; the supporting body of the sheath layer is a three-dimensional porous skeleton; both the three-dimensional porous skeleton of the core layer and the three-dimensional porous skeleton of the sheath layer are made of UHMWPE, and the density of the three-dimensional porous skeleton of the sheath layer is greater than that of the three-dimensional porous skeleton of the core layer, thus forming a dense structure in the sheath layer.

[0007] Furthermore, functional fillers are also distributed in the core layer three-dimensional porous skeleton, and functional fillers are also distributed in the skin layer three-dimensional porous skeleton.

[0008] In the aforementioned UHMWPE phase change energy storage fiber, the core layer utilizes a three-dimensional porous skeleton made of UHMWPE (Ultra-high Molecular Weight Polyethylene Fiber) to provide mechanical support. Functional fillers uniformly distributed within the three-dimensional porous skeleton improve thermal energy conversion efficiency and thermal conductivity, while the phase change energy storage material distributed within the three-dimensional channels can store thermal energy through phase change. The skin layer, primarily composed of dense UHMWPE and functional fillers, is mainly designed to prevent leakage of the phase change energy storage material. The overall structure of the aforementioned UHMWPE phase change energy storage fiber, on the one hand, improves the strength of the phase change fiber and the load capacity of the phase change energy storage material, and on the other hand, simultaneously prevents leakage of the phase change energy storage material, thus extending its service life.

[0009] The UHMWPE phase change energy storage fiber has a diameter of 1 to 200 micrometers, with the thickness of the skin layer accounting for 1% to 10% and the thickness of the core layer accounting for 90% to 99%.

[0010] The UHMWPE used in the core layer and the cortex layer has a molecular weight of 1.5 million to 10 million.

[0011] The preparation method of the above-mentioned UHMWPE phase change energy storage fiber with a core-sheath structure includes the following steps:

[0012] (1) Raw filament forming stage: After mixing raw materials such as UHMWPE, phase change energy storage material, and additives according to the ratio, the mixture is plasticized and transported by an extruder, and then continuously extruded into raw filaments through a die.

[0013] (2) Super-stretching stage: The fiber super-stretching equipment is used to super-stretch the raw yarn, and then heat-set it to form primary phase change energy storage fiber.

[0014] (3) Skin-core structure forming stage: the primary phase change energy storage fiber obtained in step (2) is continuously and rapidly passed through the extraction liquid under tension, and the phase change energy storage material on the surface layer of the primary phase change energy storage fiber is extracted; then the residual extraction liquid is rapidly volatilized through the drying tunnel at 60-140°C; in the process of volatilization of the extraction liquid, the micropores formed by UHMWPE on the surface layer of the primary phase change energy storage fiber will rapidly shrink under the action of capillary force, forming a dense skin layer; thus the UHMWPE phase change energy storage fiber is formed and wound.

[0015] Further, when functional fillers are also distributed in the core three-dimensional porous framework and the skin three-dimensional porous framework, respectively, the step (1) of the raw yarn forming stage is: UHMWPE, phase change energy storage material, functional filler and auxiliary agent are mixed according to the ratio, then plasticized and transported through the extruder, and then continuously extruded into raw yarn through the die. The step (2) of the super-drawing stage and the step (3) of the skin-core structure forming stage are the same as the above preparation method of UHMWPE phase change energy storage fiber without functional fillers.

[0016] UHMWPE, phase change energy storage material and functional filler are mixed according to the following mass fraction: phase change energy storage material is 70-95 parts, functional filler is 1-10 parts, and UHMWPE content is 4-20 parts.

[0017] The phase change energy storage material is a solid-liquid phase change energy storage material; mainly including one or more of high fatty hydrocarbons, fatty acids and their esters, and alcohols. Among them, the phase change energy storage material of high fatty hydrocarbons mainly includes alkane or paraffin with different melting points and the like; the phase change energy storage material of fatty acids and their esters mainly includes stearic acid, palmitic acid, lauric acid, myristic acid, capric acid, methyl stearate or methyl palmitate and the like; the phase change energy storage material of alcohols mainly includes polyethylene glycol, sugar alcohol or D-mannitol and the like.

[0018] The functional filler is one or more of carbon-based materials, metal materials or two-dimensional materials with light-heat conversion performance, electro-thermal conversion performance, acoustic-thermal conversion performance or magnetic-thermal conversion performance. Among them, the carbon-based material mainly includes carbon fiber, carbon nanotube, graphene, biomass-derived carbon or MOFs-derived carbon and the like; the metal material mainly includes particles or nanowires of metals such as silver (Ag), aluminum (Al), copper (Cu) and the like; the two-dimensional material mainly includes black phosphorus (BP) nanosheet, single-element two-dimensional material Xene (i.e. phosphorene, antimonene, tellurene or borophene), multi-element two-dimensional material (i.e. MXenes or TMDs), molybdenum sulfide (MoS2), nitride and the like.

[0019] In the above preparation method, in step (1), the processing temperature of the die continuous extrusion is 160-230°C;

[0020] In the step (2), when the original wire is subjected to super-drawing, the drawing temperature is 80-120 DEG C, the drawing ratio of the original wire is 5-50 times, and one-time drawing or multi-time drawing is adopted; when the heat setting treatment is performed, the heat setting temperature is 110-130 DEG C, and the heat setting time is 1-20 minutes.

[0021] In the step (3), when the primary phase change energy storage fiber continuously and rapidly passes through the extraction liquid, the time for each point on the primary phase change energy storage fiber to pass through the extraction liquid is controlled to be 30 seconds-3 minutes; when the primary phase change energy storage fiber is continuously and tensily passed through the drying channel, the time for each point on the primary phase change energy storage fiber to pass through the drying channel is controlled to be 1 second-2 minutes. In addition, in the extraction process, the corresponding extraction liquid is selected and used according to the type of the phase change energy storage material selected, and the commonly used extraction liquids include ethanol, n-hexane, dimethylbenzene, acetone or trichloromethane, etc.

[0022] In the above preparation method, the three-dimensional porous skeleton of the phase change energy storage fiber is made of the ultra-high molecular weight polyethylene, and after the original wire is extruded, the mechanical property of the phase change energy storage fiber is far higher than that of the traditional phase change energy storage fiber by means of super-drawing, so that the phase change energy storage fiber finally obtained has ultra-high strength, so as to be suitable for various application scenarios; at the same time, by means of extraction, the micropores formed by the UHMWPE on the surface layer of the phase change energy storage fiber will rapidly shrink under the action of capillary force, forming a dense skin layer, so that the density of the three-dimensional porous skeleton in the skin layer is far greater than that in the core layer, and the dense structure formed in the skin layer can effectively prevent the leakage of the phase change energy storage material in the whole phase change energy storage fiber, thereby improving the service life of the phase change energy storage fiber.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The UHMWPE phase change energy storage fiber of the present application fully utilizes the three-dimensional porous skeleton formed by the ultra-long molecular chain of UHMWPE, presents a three-dimensional gel network structure, has the advantage of ultra-high load capacity, and in the prepared phase change energy storage fiber, the load weight ratio of the phase change energy storage material is greater than 80%, and the phase change energy storage density can exceed 150 J / g. In addition, in the present application, the selection range of the phase change energy storage material in the phase change energy storage fiber is wide (such as different melting point paraffin), so that the fiber can respond to different environmental temperatures, and the application scene range is wider.

[0025] The UHMWPE phase change energy storage fiber of this invention fully utilizes the excellent mechanical properties of UHMWPE fiber. For example, when its secondary draw ratio is 8 times, its mechanical properties can reach 200 MPa, far exceeding the mechanical properties of most current phase change energy storage fibers. Furthermore, increasing the fiber's ultra-high draw ratio still significantly improves the mechanical properties of the phase change energy storage fiber. The UHMWPE phase change energy storage fiber of this invention achieves ultra-high strength and can be applied to a variety of different application scenarios.

[0026] This invention allows for the modification of fibers using different types of fillers, enabling the fibers to achieve various forms of energy conversion, such as photothermal conversion, electrothermal conversion, and acoustic-thermal conversion, and these forms of energy conversion can be integrated onto a single fiber.

[0027] The UHMWPE phase change energy storage fiber of the present invention can be prepared by a continuous production method, which is simple, easy to operate, and highly efficient, making it suitable for large-scale industrial production. Furthermore, unlike nonwoven fabrics prepared by traditional electrospinning and centrifugal spinning, the phase change energy storage fiber prepared by the present invention is a monofilament with weavability. By designing it into a suitable weaving structure, the fiber can meet the needs of various application scenarios. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the UHMWPE phase change energy storage fiber in Example 1.

[0029] Figure 2 This is a flowchart illustrating the preparation process of UHMWPE phase change energy storage fiber in Example 1.

[0030] Figure 3 This is a schematic diagram of the structure of the primary phase change energy storage fiber formed without extraction in Example 2.

[0031] Figure 4 for Figure 3 The surface SEM image of the primary phase change energy storage fiber is shown.

[0032] Figure 5 This is a schematic diagram of the structure of the UHMWPE phase change energy storage fiber formed after extraction in Example 2.

[0033] Figure 6 for Figure 5 The surface SEM image of the UHMWPE phase change energy storage fiber is shown.

[0034] In the above figures, the components indicated by the reference numerals are as follows: 1 is the skin layer, 1-1 is the three-dimensional porous skeleton of the skin layer, 2 is the core layer, 2-1 is the three-dimensional porous skeleton of the core layer, 3 is the functional filler; 4 is the extruder, 5 is the fiber ultra-stretching equipment, 6 is the extraction liquid, and 7 is the drying tunnel. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0036] Example 1

[0037] This embodiment provides a UHMWPE phase change energy storage fiber with a core-sheath structure and its preparation method.

[0038] like Figure 1 As shown, the UHMWPE phase change energy storage fiber with a core-skin structure includes a core layer 2 and a skin layer 1 arranged coaxially. The core layer is supported by a three-dimensional porous skeleton 2-1, and phase change energy storage material (not shown in the figure) is distributed in the three-dimensional channels of the core layer three-dimensional porous skeleton. The skin layer is supported by a three-dimensional porous skeleton 1-1. Both the core layer three-dimensional porous skeleton and the skin layer three-dimensional porous skeleton are made of UHMWPE. The density of the skin layer three-dimensional porous skeleton is greater than that of the core layer three-dimensional porous skeleton, and the skin layer forms a dense structure. In the core layer, a three-dimensional porous framework made of UHMWPE (Ultra-high Molecular Weight Polyethylene Fiber) provides mechanical support, and the phase change energy storage material distributed within the three-dimensional channels can store thermal energy through phase change. In the skin layer, the skin structure is mainly composed of dense UHMWPE, which is mainly to prevent leakage of the phase change energy storage material. The overall structure of the UHMWPE phase change energy storage fiber can improve the strength of the phase change fiber and the load capacity of the phase change energy storage material, while also preventing leakage of the phase change energy storage material and improving its service life.

[0039] In the aforementioned phase change energy storage fiber structure, the diameter of the UHMWPE phase change energy storage fiber is 1–200 micrometers, with the thickness of the skin layer accounting for 1%–10% and the thickness of the core layer accounting for 90%–99%. The molecular weight of the UHMWPE used in both the core layer three-dimensional porous framework and the skin layer three-dimensional porous framework is 1.5 million to 10 million.

[0040] The preparation method of the above-mentioned UHMWPE phase change energy storage fiber with core-sheath structure, such as Figure 2 As shown, it includes the following steps:

[0041] (1) Raw filament forming stage: UHMWPE, phase change energy storage material and additives are mixed according to the ratio, plasticized and transported through extruder 4, and then continuously extruded into raw filament through die head;

[0042] (2) Super-stretching stage: The fiber super-stretching equipment 5 is used to super-stretch the raw yarn, and then heat-set it to form primary phase change energy storage fiber.

[0043] (3) Core-sheath structure forming stage: the primary phase change energy storage fiber obtained in step (2) is continuously and rapidly passed through the extraction liquid in a tension state, and the phase change energy storage material on the surface layer of the primary phase change energy storage fiber is extracted; then the primary phase change energy storage fiber is continuously passed through the drying tunnel 7 at 60-140°C, and the residual extraction liquid is rapidly volatilized; in the process of volatilization of the extraction liquid, the micropores formed by the UHMWPE on the surface layer of the primary phase change energy storage fiber rapidly shrink under the action of capillary force to form a dense sheath layer; thus the UHMWPE phase change energy storage fiber is formed and wound.

[0044] In the above preparation method of the embodiment, solid paraffin (PW) with a melting point of 60°C is selected as the phase change energy storage material, and UHMWPE with a molecular weight of 5 million is selected as the matrix, wherein the mass fraction of PW is 90 parts, and the mass fraction of UHMWPE is 10 parts.

[0045] In step (1), the processing temperature of the continuous extrusion of the die is 200°C;

[0046] In step (2), when the primary fiber is subjected to super-drawing, the drawing temperature is 110°C, and the drawing is carried out in two stages, and the drawing ratios of the two stages are 4 times and 6 times respectively; when the heat setting treatment is carried out, the heat setting temperature is 115°C, and the heat setting time is 1 minute;

[0047] In step (3), xylene is selected as the extraction liquid, and when the primary phase change energy storage fiber is continuously and rapidly passed through the xylene extraction liquid tank, the time for each point on the primary phase change energy storage fiber to pass through the extraction liquid is about 1 minute, at which time the PW in the outer layer is extracted; then the primary phase change energy storage fiber is continuously passed through the drying tunnel in a tension state, and the time for each point on the primary phase change energy storage fiber to pass through the drying tunnel is about 5 minutes, at which time the xylene in the micropores of the UHMWPE remaining in the outer layer is rapidly volatilized, and in this process, capillary force is generated to cause the micropores in the outer layer to shrink to form a dense sheath layer, and finally the UHMWPE phase change energy storage fiber with a core-sheath structure is obtained (as shown in Figure 1

[0048] The UHMWPE phase change energy storage fiber with a core-sheath structure obtained in this embodiment is detected, and the diameter of the obtained phase change energy storage fiber is about 150 μm, the tensile strength reaches 200 MPa, the absorbance is 0%, there is no light-heat conversion function, the phase change enthalpy value reaches 140 J / g, and the enthalpy value remains above 97% after 100 cycles of testing.

[0049] Embodiment 2

[0050] The embodiment provides an UHMWPE phase change energy storage fiber with a core-sheath structure and a preparation method thereof.

[0051] As Figure 5 ​As shown, the UHMWPE phase change energy storage fiber with the core-sheath structure includes a core layer 2 and a sheath layer 1 arranged coaxially, the support body of the core layer is a three-dimensional porous framework 2-1 of the core layer, the three-dimensional pores of the three-dimensional porous framework of the core layer are distributed with phase change energy storage materials (not shown in the figure), and the support body of the sheath layer is a three-dimensional porous framework 1-1 of the sheath layer; the three-dimensional porous framework of the core layer and the three-dimensional porous framework of the sheath layer are both made of UHMWPE, the density of the three-dimensional porous framework of the sheath layer is greater than the density of the three-dimensional porous framework of the core layer, and the sheath layer forms a dense structure; in addition, the three-dimensional porous framework of the core layer is also distributed with functional fillers 3, and the three-dimensional porous framework of the sheath layer is also distributed with functional fillers 3. In the above UHMWPE phase change energy storage fiber, in the core layer, the three-dimensional porous framework made of UHMWPE (Ultra-high Molecular Weight Polyethylene Fiber, i.e. ultra-high molecular weight polyethylene) provides mechanical support, the functional fillers uniformly distributed in the three-dimensional porous framework can improve the thermal energy conversion efficiency and heat conduction, and the phase change energy storage materials distributed in the three-dimensional pores can store thermal energy through phase change; and in the sheath layer, the sheath structure is mainly composed of dense UHMWPE and functional fillers, which is mainly to prevent the phase change energy storage materials from leaking; the overall structure of the above UHMWPE phase change energy storage fiber can not only improve the strength of the phase change fiber and the load capacity of the phase change energy storage materials, but also can prevent the phase change energy storage materials from leaking and improve the service life.

[0052] In the above phase change energy storage fiber structure, the diameter of the UHMWPE phase change energy storage fiber is 1-200 microns, the thickness ratio of the sheath layer is 1%-10%, and the thickness ratio of the core layer is 90%-99%. The molecular weight of the UHMWPE used in the three-dimensional porous framework of the core layer and the three-dimensional porous framework of the sheath layer is 1.5 million-10 million. Among them, the functional fillers can be selected from one or more of graphene, carbon nanotubes, expanded graphite, carbon black, aluminum particles, aluminum nanowires, copper particles, and copper nanowires. The photo-thermal conversion fillers can be selected from one or more of gold nanocrystals, silver nanoparticle crystals, platinum nanocrystals, lead nanocrystals, black titanium dioxide, titanium sesquioxide, carbon nanotubes, carbon black, graphene, graphene oxide, and biomass-derived amorphous carbon.

[0053] The preparation method of the above UHMWPE phase change energy storage fiber with the core-sheath structure is the same as that of Example 1, and specifically includes the following steps:

[0054] (1) The original wire forming stage: UHMWPE, phase change energy storage materials, functional fillers, and auxiliaries are mixed according to the proportion, plasticized and transported through an extruder 4, and then continuously extruded into an original wire through a die;

[0055] (2) Super-drawing stage: the original fiber is super-drawn by a fiber super-drawing device 5, and then is heat-set to form a primary phase-change energy storage fiber (the structural principle thereof is shown in Figure 3 , and the surface layer structure thereof is shown in Figure 4 );

[0056] (3) Skin-core structure forming stage: the primary phase-change energy storage fiber obtained in step (2) is continuously and rapidly passed through an extraction liquid in a tensioned state, and the phase-change energy storage material in the surface layer of the primary phase-change energy storage fiber is extracted; then the primary phase-change energy storage fiber is continuously passed through an oven 7 at 60-140°C, and the residual extraction liquid is rapidly volatilized; in the process of volatilization of the extraction liquid, the micropores formed by the UHMWPE in the surface layer of the primary phase-change energy storage fiber rapidly shrink under the action of capillary force to form a dense skin layer; thus, the UHMWPE phase-change energy storage fiber (the structural principle thereof is shown in Figure 5 , and the surface layer structure thereof is shown in Figure 6 ) is formed and is wound up.

[0057] In the above preparation method of the embodiment, n-tetracosane with a melting point of 50°C is selected as the phase-change energy storage material, UHMWPE with a molecular weight of 5 million is selected as the matrix, and carbon black (CB) is selected as the functional filler. The mass fraction of n-tetracosane is 85 parts, the mass fraction of UHMWPE is 10 parts, and the mass fraction of CB is 5 parts.

[0058] In step (1), the processing temperature of the continuous extrusion of the die is 200°C;

[0059] In step (2), when the original fiber is super-drawn, the drawing temperature is 110°C, and the drawing is performed in two stages, and the drawing ratios of the two stages are 5 times and 6 times, respectively; when the heat setting is performed, the heat setting temperature is 110°C, and the heat setting time is 1 minute;

[0060] In step (3), xylene is selected as the extraction liquid, and when the primary phase-change energy storage fiber continuously and rapidly passes through the xylene extraction liquid tank, the time for each point on the primary phase-change energy storage fiber to pass through the extraction liquid is about 1 minute, at which time the n-tetracosane in the outer layer is extracted; then the primary phase-change energy storage fiber is continuously passed through the oven at 90°C in a tensioned state, and the time for each point on the primary phase-change energy storage fiber to pass through the oven is about 5 seconds, at which time the xylene in the micropores of the UHMWPE remaining in the outer layer is rapidly volatilized, and in this process, capillary force is generated to cause the micropores in the outer layer to shrink to form a dense skin layer, and finally the UHMWPE phase-change energy storage fiber with a skin-core structure (as shown in Figure 5 ) is prepared.

[0061] The UHMWPE phase change energy storage fiber with the sheath-core structure prepared in the embodiment is detected, the diameter of the obtained phase change energy storage fiber is about 120 μm, the absorbance is 96% and the phase change energy storage fiber has the light-heat conversion function, the tensile strength reaches 240 MPa, the phase change enthalpy value reaches 170 J / g, and the enthalpy value still remains above 97% after 100 cycle tests.

[0062] As described above, the application can be better implemented, and the above-mentioned embodiments are only the preferred embodiments of the application, but not used to limit the implementation scope of the application; that is, all equivalent changes and modifications made according to the contents of the application are covered in the scope of the claims of the application.

Claims

1. A UHMWPE phase change energy storage fiber with a core-sheath structure, characterized in that, It includes a core layer and a skin layer arranged coaxially. The core layer is supported by a three-dimensional porous skeleton, and phase change energy storage material is distributed in the three-dimensional channels of the core layer three-dimensional porous skeleton. The skin layer is supported by a three-dimensional porous skeleton. Both the core layer three-dimensional porous skeleton and the skin layer three-dimensional porous skeleton are made of UHMWPE. The density of the skin layer three-dimensional porous skeleton is greater than that of the core layer three-dimensional porous skeleton, and the skin layer forms a dense structure. UHMWPE phase change energy storage fiber is prepared using the following method: (1) Raw filament forming stage: UHMWPE, phase change energy storage material and additives are mixed according to the ratio, plasticized and transported by an extruder, and then continuously extruded into raw filaments through a die; (2) Super-stretching stage: The fiber super-stretching equipment is used to super-stretch the raw yarn, and then heat-set it to form primary phase change energy storage fiber. (3) Core-Sheet Structure Formation Stage: The primary phase change energy storage fiber obtained in step (2) is continuously and rapidly passed through the extraction liquid under tension to extract the phase change energy storage material on the surface of the primary phase change energy storage fiber; then it is passed through a drying tunnel at 60-140℃ to make the residual extraction liquid evaporate rapidly. During the evaporation of the extract, the micropores formed by UHMWPE on the surface of the primary phase change energy storage fiber will rapidly shrink under the action of capillary force, forming a skin with a dense structure; thus, UHMWPE phase change energy storage fiber is formed.

2. The UHMWPE phase change energy storage fiber with a core-sheath structure according to claim 1, characterized in that, Functional fillers are also distributed in the three-dimensional porous skeleton of the core layer and the three-dimensional porous skeleton of the skin layer.

3. The UHMWPE phase change energy storage fiber with a core-sheath structure according to claim 1 or 2, characterized in that, The UHMWPE phase change energy storage fiber has a diameter of 1 to 200 micrometers, with the thickness of the skin layer accounting for 1% to 10% and the thickness of the core layer accounting for 90% to 99%.

4. A UHMWPE phase change energy storage fiber with a core-sheath structure according to claim 1 or 2, characterized in that, The UHMWPE used in the core layer and the cortex layer has a molecular weight of 1.5 million to 10 million.

5. The method for preparing a UHMWPE phase change energy storage fiber with a core-sheath structure as described in claim 1, characterized in that, Includes the following steps: (1) Raw filament forming stage: UHMWPE, phase change energy storage material and additives are mixed according to the ratio, plasticized and transported by an extruder, and then continuously extruded into raw filaments through a die; (2) Super-stretching stage: The fiber super-stretching equipment is used to super-stretch the raw yarn, and then heat-set it to form primary phase change energy storage fiber. (3) Core-Sheet Structure Formation Stage: The primary phase change energy storage fiber obtained in step (2) is continuously and rapidly passed through the extraction liquid under tension to extract the phase change energy storage material on the surface of the primary phase change energy storage fiber; then it is passed through a drying tunnel at 60-140℃ to make the residual extraction liquid evaporate rapidly. During the evaporation of the extract, the micropores formed by UHMWPE on the surface of the primary phase change energy storage fiber will rapidly shrink under the action of capillary force, forming a skin with a dense structure; thus, UHMWPE phase change energy storage fiber is formed.

6. The method for preparing a UHMWPE phase change energy storage fiber with a core-sheath structure according to claim 5, characterized in that, When functional fillers are distributed in the core layer three-dimensional porous skeleton and the skin layer three-dimensional porous skeleton respectively, the filament forming stage of step (1) is as follows: after mixing UHMWPE, phase change energy storage material, functional filler and additives according to the ratio, they are plasticized and transported by an extruder, and then continuously extruded into filaments through a die.

7. The method for preparing a UHMWPE phase change energy storage fiber with a core-sheath structure according to claim 6, characterized in that, The UHMWPE, phase change energy storage material, and functional filler are formulated in the following proportions by mass: 70-95 parts of phase change energy storage material, 1-10 parts of functional filler, and 4-20 parts of UHMWPE.

8. The method for preparing a UHMWPE phase change energy storage fiber with a core-sheath structure according to claim 6, characterized in that, The phase change energy storage material is a solid-liquid phase change energy storage material; The functional filler is one or more of carbon-based materials or metallic materials that have photothermal conversion properties, electrothermal conversion properties, acoustic-thermal conversion properties, or magnetocaloric conversion properties.

9. The method for preparing a UHMWPE phase change energy storage fiber with a core-sheath structure according to claim 5, characterized in that, In step (1), the processing temperature of the continuous extrusion by the die head is 160-230℃; In step (2), when the raw yarn is subjected to super-stretching, the stretching temperature is 80-120℃, the stretching ratio of the raw yarn is 5-50 times, and the stretching method is one stretch or multiple stretching; during heat setting treatment, the heat setting temperature is 110-130℃, and the heat setting time is 1-20 minutes.

10. The method for preparing a UHMWPE phase change energy storage fiber with a core-sheath structure according to claim 5, characterized in that, In step (3), when the primary phase change energy storage fiber passes through the extraction liquid continuously and rapidly, the time for each point on the primary phase change energy storage fiber to pass through the extraction liquid is controlled between 30 seconds and 3 minutes; when the primary phase change energy storage fiber passes through the drying tunnel under tension continuously, the time for each point on the primary phase change energy storage fiber to pass through the drying tunnel is controlled between 1 second and 2 minutes.

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