Extremely cold resistant down jacket fabric and preparation method thereof

Abstract

The invention discloses an extremely cold-resistant down jacket fabric and a preparation method thereof. The preparation method comprises the following steps: mixing hot-pressing ceramic particles, a polyvinylidene fluoride polymer matrix, a thermoplastic polyurethane synergistic matrix and a heat conduction filler to prepare a hot-pressing composite material; s2, spinning the hot-pressing composite material prepared in the step S1 into hot-pressing composite fibers, and carrying out mechanical stretching or electric field polarization treatment; s2, weaving the hot-pressing composite fibers treated in the step S2 into a hot-pressing inner layer with a three-dimensional coil structure and a porous structure; laminating the high-elasticity blended material, the aerogel thermal insulation material and the waterproof breathable film material to form a compressed outer layer; the hot pressing inner layer is arranged on the inner side of the compression outer layer; the integrity is ensured through the lamination technology, when a wearer exercises, the pressure applied by the compression outer layer and the internal deformation work cooperatively, so that mechanical energy is converted into heat, and the heat is rapidly conducted through the heat conduction network; meanwhile, the aerogel layer blocks heat loss, and the PU film discharges moisture to keep dry and comfortable.

Description

Technical Field

[0001] This invention relates to the field of double-layered extreme cold-resistant down jacket fabric, and more particularly to an extreme cold-resistant down jacket fabric and its preparation method. Background Technology

[0002] Modern functional textiles play an increasingly important role in enhancing human performance and comfort, especially in the sports and outdoor sectors, where the demand for high-performance protective equipment continues to grow. Among these advancements, design principles that optimize human physiological responses to improve efficiency and reduce energy consumption have become a significant trend in current technological development. Such innovations are not only related to athletic performance but also closely linked to survival and health maintenance in extreme environments.

[0003] Significant progress has been made in the application of ergonomic principles to functional wearable devices in existing technologies. For example, in footwear design, the industry has successfully introduced and applied the ergonomic design concept of multi-point support (such as seven-point support). This type of design effectively disperses foot pressure through precise mechanical distribution, thereby making the body load more balanced, significantly reducing energy consumption during walking or exercise, and thus delaying the onset of fatigue. The core of this principle lies in optimizing the interaction between the external support structure and human biomechanics to achieve energy conservation and improved comfort. Based on this, it has been widely applied in specific functional clothing, especially sportswear. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides an extremely cold-resistant down jacket fabric and its preparation method.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing an extremely cold-resistant down jacket fabric, comprising the following steps:

[0006] S1: A pressure-heated composite material is prepared by mixing pressure-heated ceramic particles, polyvinylidene fluoride polymer matrix, thermoplastic polyurethane synergistic matrix and thermally conductive filler.

[0007] S2: The compressive heat composite material prepared in S1 is spun into compressive heat composite fiber and subjected to mechanical stretching or electric field polarization treatment.

[0008] S3: The pressure-heating composite fibers treated with S2 are woven into a pressure-heating inner layer with a three-dimensional coil structure and a porous structure;

[0009] S4: High-elasticity blended materials, aerogel insulation materials and waterproof and breathable membrane materials are laminated to form a compressed outer layer;

[0010] S5: The pressurized inner layer prepared in S3 is tightly integrated with the compressed outer layer prepared in S4, and the pressurized inner layer is placed inside the compressed outer layer.

[0011] S1: A pressure-heated composite material is prepared by mixing pressure-heated ceramic particles, polyvinylidene fluoride polymer matrix, thermoplastic polyurethane synergistic matrix and thermally conductive filler.

[0012] In a preferred embodiment of the present invention, in S1, the pressure-heated ceramic particles are tetragonal barium titanate particles with a particle size of 50 nm to 200 nm; the polyvinylidene fluoride polymer matrix has a weight-average molecular weight of 200,000 to 500,000 and has a piezoelectric active β phase content of 50% to 70%; the thermoplastic polyurethane synergistic matrix has a Shore hardness of 80 A to 95 A; and the thermally conductive filler is sheet-like graphene or carbon nanotubes with a volume fraction of 5% to 15%.

[0013] In a preferred embodiment of the present invention, in S1, the pressure-heated ceramic particles account for 3%-7% of the mass of the polyvinylidene fluoride (PVDF) polymer matrix, the thermoplastic polyurethane synergistic matrix accounts for 10%-30% of the mass of the PVDF polymer matrix, and the thermally conductive filler accounts for 5%-15% of the mass of the PVDF polymer matrix. The mixture is prepared by using a twin-screw extruder at 180-220°C and a screw speed of 100-200 rpm.

[0014] In a preferred embodiment of the present invention, in S2, the hot-pressed composite fiber spinning includes controlling the spinning temperature to 200-400℃, the draw ratio to 2-5:1, the linear density to 100-200 denier, the mechanical stretching temperature to 100-1140℃, and the electric field polarization electric field strength to 10-30kV / mm.

[0015] In a preferred embodiment of the present invention, in S3, the hot-pressed inner layer weaving includes forming a three-dimensional coil structure with a coil diameter of 0.5mm-2mm and a coil density of 200 to 500 coils per square centimeter by weft knitting or warp knitting techniques; the porous structure has a porosity of 30% to 60% and an average pore size of 50 micrometers to 200 micrometers.

[0016] In a preferred embodiment of the present invention, in S4, the high-elasticity blended material is selected from spandex fiber with a mass fraction of 15%-30% and nylon fiber with a mass fraction of 70%-85%; the aerogel insulation material is selected from flexible silicone aerogel felt with a thickness of 1-3mm, the lamination and encapsulation temperature is 100-200℃, and the pressure is 0.1-1.0MPa; the waterproof and breathable membrane material is selected from polyurethane film with a thickness of 15-50µm, and in S5, the composite temperature is 120-140℃.

[0017] A cold-resistant down jacket fabric, comprising a double-layer composite structure.

[0018] The double-layer composite structure consists of a pressurized inner layer and a compressed outer layer;

[0019] The inner heat-pressing layer is located inside the outer compression layer;

[0020] When the wearer moves, the inner heat-pressurizing layer can actively convert and conduct mechanical energy into heat energy by compressing the pressure applied by the outer layer and its own deformation.

[0021] In a preferred embodiment of the present invention, the pressurized inner layer is woven from pressurized composite fibers. The core components of the pressurized composite fibers include pressurized ceramic particles, polyvinylidene fluoride (PVDF) polymer matrix, thermoplastic polyurethane (TPU) synergistic matrix, and thermally conductive filler. The pressurized ceramic particles are barium titanate (BaTiO) particles with a tetragonal crystalline structure.

[0022] In a preferred embodiment of the present invention, the compressed outer layer comprises a highly elastic blended material, an aerogel insulation material, and a waterproof and breathable membrane material.

[0023] In a preferred embodiment of the present invention, the pressure-heating composite fibers in the pressure-heating inner layer are woven into a three-dimensional coil structure. The three-dimensional coil structure can produce significant macroscopic deformation when subjected to slight mechanical pressure, thereby effectively amplifying the stress transmitted to the interior of the pressure-heating composite material.

[0024] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0025] (1) This invention provides an extremely cold-resistant down jacket fabric and its preparation method. The fabric is a pressure-heat composite material formed by BaTiO3 particles, PVDF resin, TPU particles, and thermally conductive fillers in a pressure-heat inner layer. This composite material is then spun and woven into a three-dimensional coil structure. When the wearer moves, external mechanical stress is amplified through coil deformation, activating the piezoelectric effect of BaTiO3 and PVDF to generate a micro-electric field. This induces the polarization of the TPU molecular chains, releasing heat through an entropy reduction mechanism. The heat is then rapidly conducted to the skin surface by a continuous thermally conductive network constructed from graphene and other fillers, converting the mechanical energy of daily human activities into replenishing heat energy in real time, providing the wearer with immediate and continuous heat supply. Compared to existing technologies, traditional down jackets are significantly colder. Relying on passive insulation materials (such as down or synthetic fiber cotton) to block heat loss can easily lead to hypothermia when the human body's heat production is insufficient in extremely cold environments. This invention innovatively introduces an active heat generation mechanism, which makes up for the limitations of passive insulation. Furthermore, this active heat generation capability works in synergy with passive insulation layers such as aerogel to significantly improve the thermal balance performance of the fabric under extreme low temperature conditions, effectively prevent the risk of hypothermia, and extend the safe time for outdoor activities.

[0026] (2) This invention provides an extremely cold-resistant down jacket fabric and its preparation method. By compressing the outer layer with a gradient compression design, the wearer's blood circulation and exercise physiological performance are optimized. By providing a decreasing pressure of 25 mmHg at the distal end and 12 mmHg at the proximal end, this gradient pressure stimulates vascular endothelial cells to release active substances such as nitric oxide through biomechanical action, promoting the centripetal return of venous blood and lymph, thereby accelerating the removal of metabolic waste, significantly improving local blood circulation efficiency, and reducing muscle fatigue and post-exercise soreness. Compared with existing technologies, most conventional sportswear lacks a scientific pressure gradient design or only provides uniform compression, and cannot specifically optimize hemodynamics. This invention, based on ergonomics, achieves a precise decrease in pressure from distal to proximal, which is more in line with physiological needs. Furthermore, this design can also limit muscle vibration during high-speed exercise, save energy consumption, reduce the risk of injury, and alleviate stress responses such as edema caused by high-altitude environments, thereby enhancing overall athletic performance and safety.

[0027] (3) This invention provides an extremely cold-resistant down jacket fabric and its preparation method. Through the double-layer composite structure of the heat-pressing inner layer and the compression outer layer, the efficient synergy of passive heat preservation, active heat generation and protection functions is achieved. The three-dimensional porous coil structure of the heat-pressing inner layer amplifies mechanical stress and activates the heat-pressing effect when under pressure. The compression outer layer integrates aerogel insulation material and PU waterproof and breathable membrane. The overall integrity is ensured through lamination technology. When the wearer moves, the pressure applied by the compression outer layer and the internal deformation work together to convert mechanical energy into heat and conduct it quickly through the heat conduction network. At the same time, the aerogel layer blocks heat loss and the PU membrane releases moisture to keep dry. This allows the fabric to actively replenish heat in extremely cold environments and has excellent heat preservation, waterproof and breathability. Compared with the existing technology, traditional down jackets often sacrifice freedom of movement due to the thickness of the material, and the accumulation of moisture can easily lead to a decrease in heat preservation performance. This invention achieves the integration of multiple functions under the premise of lightweight through material and structural innovation. Furthermore, this integrated design improves wearing comfort and durability, and is especially suitable for long-term outdoor extreme cold activities, providing comprehensive protection for users. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a three-dimensional structural diagram of a preferred embodiment of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0032] As shown in the figure, the preparation method of an extremely cold-resistant down jacket fabric according to the present invention includes the following steps:

[0033] S1: A pressure-heated composite material is prepared by mixing pressure-heated ceramic particles, polyvinylidene fluoride polymer matrix, thermoplastic polyurethane synergistic matrix and thermally conductive filler.

[0034] S2: The compressive heat composite material prepared in S1 is spun into compressive heat composite fiber and subjected to mechanical stretching or electric field polarization treatment.

[0035] S3: The pressure-heating composite fibers treated with S2 are woven into a pressure-heating inner layer with a three-dimensional coil structure and a porous structure;

[0036] S4: High-elasticity blended materials, aerogel insulation materials and waterproof and breathable membrane materials are laminated to form a compressed outer layer;

[0037] S5: The pressurized inner layer prepared in S3 is tightly integrated with the compressed outer layer prepared in S4, and the pressurized inner layer is placed inside the compressed outer layer.

[0038] This invention provides a method for preparing a down jacket fabric for extreme cold resistance. By converting the unavoidable mechanical energy during human movement into sustainable supplemental heat energy, an intelligent heat preservation mechanism combining active heat generation and passive heat preservation is achieved. By constructing a double-layer composite structure, the inner layer is a pressure-heat inner layer, which is essentially an energy harvesting and conversion system. This layer is woven from PVDF / TPU composite fibers doped with tetragonal barium titanate nanoparticles and thermally conductive fillers such as graphene, and is subjected to mechanical stretching or electric field polarization treatment to give it a high content of piezoelectric β crystal phase.

[0039] When the wearer moves, their body movements exert continuous micro-pressure and deformation on the fabric. These mechanical effects are first captured and amplified by the unique three-dimensional coils and porous structure of the heat-pressing inner layer, and then transformed into significant stress on the internal composite fibers. This stress activates the piezoelectric effect of PVDF and barium titanate, generating a local micro-electric field. This electric field then drives the molecular chain dipoles in the TPU synergistic matrix to align in an orientation, resulting in a sharp decrease in the conformational entropy of the molecular chains. According to the laws of thermodynamics, this entropy reduction process releases heat into the environment, thus efficiently converting mechanical energy into thermal energy. Subsequently, a continuous heat-conducting network constructed from graphene and other materials rapidly conducts the generated heat to the skin surface, achieving instant heating.

[0040] The outer layer, or compression layer, is a composite of a highly elastic blended material with gradient compression properties, an ultra-insulating aerogel layer, and a waterproof and breathable PU film. In addition to providing windproof, waterproof, and passive insulation, its gradient compression structure applies appropriately decreasing pressure to the body from the distal to the proximal extremities. This gradient pressure promotes blood circulation and lymphatic drainage, reduces muscle fatigue, improves exercise endurance, and provides a continuous and uniform mechanical load to the inner layer, ensuring that the heat-generating inner layer is effectively activated and continues to function even during light activity. Through the synergistic effect of the two layers, the fabric provides excellent passive insulation under static conditions through the aerogel and sealed structure, and achieves efficient active heat generation under dynamic conditions through the conversion of mechanical energy into thermal energy.

[0041] S1: A pressure-heated composite material is prepared by mixing pressure-heated ceramic particles, polyvinylidene fluoride polymer matrix, thermoplastic polyurethane synergistic matrix and thermally conductive filler.

[0042] In a preferred embodiment of the present invention, in S1, the pressure-heated ceramic particles are tetragonal barium titanate particles with a particle size of 50 nm to 200 nm; the polyvinylidene fluoride polymer matrix has a weight-average molecular weight of 200,000 to 500,000 and has a piezoelectric active β phase content of 50% to 70%; the thermoplastic polyurethane synergistic matrix has a Shore hardness of 80 A to 95 A; and the thermally conductive filler is sheet-like graphene or carbon nanotubes with a volume fraction of 5% to 15%.

[0043] In a preferred embodiment of the present invention, in S1, the pressure-heated ceramic particles account for 3%-7% of the mass of the polyvinylidene fluoride (PVDF) polymer matrix, the thermoplastic polyurethane synergistic matrix accounts for 10%-30% of the mass of the PVDF polymer matrix, and the thermally conductive filler accounts for 5%-15% of the mass of the PVDF polymer matrix. The mixture is prepared by using a twin-screw extruder at 180-220°C and a screw speed of 100-200 rpm.

[0044] It should be noted that in this step, the mixing preparation specifically involves mixing tetragonal barium titanate (BaTiO3) particles with an average particle size of 50 nm to 200 nm, polyvinylidene fluoride (PVDF) resin with a weight-average molecular weight range of 200,000 to 500,000, thermoplastic polyurethane (TPU) particles with a Shore hardness range of 80 A to 95 A, and sheet-like graphene or carbon nanotube thermally conductive fillers with a volume fraction of 5% to 15%, according to a preset ratio. The mixture is then melt-blended using a twin-screw extruder at a temperature of 180°C to 220°C to obtain uniformly dispersed thermocomposite material particles.

[0045] In the above steps, tetragonal barium titanate (BaTiO3) particles with an average particle size of 100 nm, polyvinylidene fluoride (PVDF) resin with a weight average molecular weight of 350,000, thermoplastic polyurethane (TPU) particles with a Shore hardness of 90 A, and sheet graphene thermal conductive filler with a volume fraction of 10% are weighed and mixed in a certain proportion. Specifically, the mass ratio is as follows: BaTiO3 particles account for 5% of the mass of PVDF resin, TPU particles account for 20% of the mass of PVDF resin, and graphene filler accounts for 10% of the mass of PVDF resin.

[0046] The mixture is then fed into a twin-screw extruder for melt blending within a temperature range of 190°C to 210°C. The screw speed of the extruder is maintained at 150 rpm to ensure that the components are fully sheared and mixed in the molten state, thereby obtaining uniformly dispersed compressive heat-conducting composite particles. This ensures the uniform distribution of BaTiO3 in the PVDF / TPU matrix and the effective construction of the graphene thermally conductive network.

[0047] S2: The compressive heat composite material prepared in S1 is spun into compressive heat composite fiber and subjected to mechanical stretching or electric field polarization treatment.

[0048] In a preferred embodiment of the present invention, in S2, the hot-pressed composite fiber spinning includes controlling the spinning temperature to 200-400℃, the draw ratio to 2-5:1, the linear density to 100-200 denier, the mechanical stretching temperature to 100-1140℃, and the electric field polarization electric field strength to 10-30kV / mm.

[0049] It should be noted that this step involves controlling the spinning temperature to 200℃ to 240℃ and the draw ratio to 2:1 to 5:1 to spin the thermoplastic composite material into thermoplastic composite fibers with a specific linear density. After spinning, the fibers undergo subsequent mechanical stretching or electric field polarization treatment to increase the content of the piezoelectric β phase in the PVDF and enhance its piezoelectric response.

[0050] This step involves melt spinning the piezoelectric composite material particles prepared in the previous step, controlling the spinning temperature at 220℃ and the draw ratio at 4:1, to spin the molten composite material into continuous piezoelectric composite fibers with a linear density of 150 denier. After spinning, the fibers are subjected to mechanical stretching or electric field polarization treatment. Mechanical stretching involves placing the spun fibers under a stretching device and performing two-stage stretching at an ambient temperature of 120℃, with a total stretch ratio of 4 times, to induce the formation and orientation of the β-phase crystal structure in the PVDF molecular chain, thereby significantly improving its piezoelectric response. Electric field polarization treatment involves polarizing the fibers under an electric field strength of 20kV / mm to further optimize the piezoelectric activity.

[0051] Among the various crystal forms of PVDF, the α phase is the most thermodynamically stable and the most common. Its molecular chains have a helical conformation with opposite dipole moments, and it does not exhibit piezoelectricity macroscopically. The β phase, on the other hand, has strong piezoelectric activity. Its molecular chains have an all-trans planar zigzag conformation with dipole moments all aligned in the same direction, thus exhibiting a strong piezoelectric effect macroscopically.

[0052] During mechanical stretching, external tensile force is applied to provide sufficient energy and driving force to the PVDF molecular chain, causing it to undergo a solid-solid phase transition from the lower-energy but non-piezoelectric α phase to the higher-energy but piezoelectric β phase, resulting in molecular chain conformation rearrangement and crystal structure reconstruction.

[0053] In this step, the spun, heat-pressed composite fiber undergoes two-stage mechanical stretching at an ambient temperature of 120°C, achieving a total draw ratio of 4. 120°C is higher than the glass transition temperature of PVDF but lower than its melting point. At this temperature, the molecular chain segments of PVDF possess sufficient mobility, but the entire crystal structure has not yet melted. When uniaxial tensile stress is applied to the fiber, the enormous stretching force generated along the stretching direction acts on the spherulitic structure of PVDF. This stress straightens and orients the molecular chains in the amorphous regions and disrupts the stability of the helical molecular chains in the original α-phase crystal, forcing the molecular chains to transform from a lower-energy helical conformation to a higher-energy all-trans planar zigzag conformation. During this chain segment extension and rearrangement process, fluorine and hydrogen atoms on the molecular chains are arranged on both sides of the carbon chain, forming an ordered structure with unidirectional dipole moments, i.e., the β-phase crystal.

[0054] Therefore, during the mechanical stretching process, the orientation degree of the molecular chains and the completeness of the phase transition are controlled by controlling the stretching ratio. As the stretching ratio increases, the molecular chains are stretched straighter and the orientation degree is higher, resulting in a higher proportion of transformation from the α phase to the β phase. This allows the β phase content in this step to increase from 60% after pretreatment to over 85%. After stretching, orientation, and fixation, the β phase molecular chains act like countless tiny magnets with the same orientation. When the fabric is subsequently deformed by the wearer's movements, these oriented dipole moments will undergo relative displacement, thereby generating charges at both ends of the material, i.e., the piezoelectric effect. This provides an essential initial electric field for triggering the entropy reduction heat generation of TPU, i.e., the piezoelectric effect.

[0055] S3: The pressure-heating composite fibers treated with S2 are woven into a pressure-heating inner layer with a three-dimensional coil structure and a porous structure;

[0056] In a preferred embodiment of the present invention, in S3, the hot-pressed inner layer weaving includes forming a three-dimensional coil structure with a coil diameter of 0.5mm-2mm and a coil density of 200 to 500 coils per square centimeter by weft knitting or warp knitting techniques; the porous structure has a porosity of 30% to 60% and an average pore size of 50 micrometers to 200 micrometers.

[0057] It should be noted that in this step, by adjusting the yarn feed tension to 1.5 cN and the needle bed density to 28 stitches / inch during the knitting process, a structure with a loop diameter of 0.5 mm to 2 mm and a loop density of 200 to 500 loops per square centimeter is formed. Simultaneously, a porous structure with a porosity of 30% to 60% is formed by adding and subsequently removing a pore-forming agent before spinning or knitting, or by controlling the knitting parameters.

[0058] In this step, during the weaving process, the heat-pressed composite fibers are woven using a weft knitting or warp knitting machine to form a three-dimensional coil structure fabric. By precisely adjusting the yarn feeding tension, needle bed density, and sinker position, a coil with a diameter of 1 mm and a coil density of 350 coils per square centimeter is finally obtained. At the same time, in order to form a porous structure with a porosity of 45%, polyethylene glycol (PEG) is used as a pore-forming agent before the heat-pressed composite material is spun, and is removed by washing with water after weaving.

[0059] S4: High-elasticity blended materials, aerogel insulation materials and waterproof and breathable membrane materials are laminated to form a compressed outer layer;

[0060] In a preferred embodiment of the present invention, in S4, the high-elasticity blended material is selected from spandex fiber with a mass fraction of 15%-30% and nylon fiber with a mass fraction of 70%-85%; the aerogel insulation material is selected from flexible silicone aerogel felt with a thickness of 1-3mm, the lamination and encapsulation temperature is 100-200℃, and the pressure is 0.1-1.0MPa; the waterproof and breathable membrane material is selected from polyurethane film with a thickness of 15-50µm, and in S5, the composite temperature is 120-140℃.

[0061] It should be noted that in this step, 15% to 30% spandex fiber by mass is mixed with 70% to 85% nylon or polyester fiber by mass, and the mixture is prepared into a blended yarn by ring spinning or air-jet spinning. The blended yarn is then knitted into a highly elastic blended material with gradient compression properties by a circular knitting machine or a flat warp knitting machine. The gradient compression is achieved by adjusting the knitting density and yarn tension in different areas to ensure that a compression pressure of 20 mmHg to 30 mmHg is provided at the distal end of the limb and a compression pressure of 10 mmHg to 15 mmHg is provided at the proximal end of the limb.

[0062] In the above steps, 25% spandex fiber and 75% nylon 6 fiber by mass are mixed and prepared into a high-strength blended yarn using ring spinning. The blended yarn is then knitted using a circular knitting machine with a multi-zone tension control system to form a highly elastic blended material with gradient compression properties. The gradient compression effect is achieved by precisely adjusting the knitting density and yarn feed tension in different zones during the knitting process. Specifically, in the zone corresponding to the distal end of the limb, the knitting density is set to 28 stitches / inch and the yarn tension is set to 1.5 cN to provide a compression pressure of 25 mmHg; while in the zone corresponding to the proximal end of the limb, the knitting density is set to 24 stitches / inch and the yarn tension is set to 1.0 cN to provide a compression pressure of 12 mmHg.

[0063] In the above steps, flexible aerogel felt sheets or aerogel microcapsules with a thickness of 1 mm to 3 mm are uniformly or locally fixed to the inner side of the highly elastic blended material by lamination or sewing.

[0064] In the above encapsulation process, a flexible silicone aerogel felt sheet with a thickness of 2 mm is fixed to the inside of a highly elastic blended material by hot pressing. The lamination temperature is controlled at 150°C, the pressure is 0.5 MPa, and the time is 30 seconds to ensure that the aerogel felt sheet is firmly bonded to the fabric without damaging the microstructure of the aerogel. To improve the bonding strength, a thin layer of hot melt adhesive can be pre-coated on the surface of the aerogel felt sheet.

[0065] After encapsulation, a polyurethane (PU) film with a thickness of 15 to 50 micrometers is laminated onto the outer surface of a highly elastic blended material using hot melt adhesive lamination or wet lamination processes to form a compressed outer layer. In the wet lamination process, an environmentally friendly polyurethane adhesive is used, and the material is dried and cured at 130°C.

[0066] S5: The pressurized inner layer prepared in S3 is tightly integrated with the compressed outer layer prepared in S4, and the pressurized inner layer is placed inside the compressed outer layer.

[0067] It should be noted that this step involves combining and integrating the two layers prepared in the previous steps. Specifically, the two layers consist of a heat-pressed inner layer and a compression outer layer. The heat-pressed inner layer and the compression outer layer are tightly combined and integrated along their edges and pre-set structural lines using a precise sewing process. High-strength polyester thread is used in the sewing process, and a flatlock stitch technique is employed to ensure that the seams are flat and comfortable, avoiding irritation to the wearer's skin. Moreover, this sewing method ensures that the heat-pressed inner layer is always located on the inside and in contact with the skin, while the outer layer provides structural support and external protection, thus ultimately completing the preparation of the extreme cold-resistant down jacket fabric.

[0068] In summary, the extreme cold-resistant down jacket fabric prepared in this invention, through its ergonomically designed gradient compression outer layer, applies a continuous pressure to the wearer's body that decreases from distal to proximal. This pressure stimulates vascular endothelial cells to release vasoactive substances, promoting effective venous blood and lymph return, thereby improving blood circulation efficiency, reducing the accumulation of metabolic waste, significantly reducing muscle fatigue, and alleviating physiological stress responses caused by high-altitude environments. Simultaneously, the gradient compression's tight wrapping of muscles effectively restricts unnecessary muscle vibration during exercise, further conserving energy and reducing the risk of muscle injury.

[0069] The above applies continuous pressure to the wearer's body, decreasing from distal to proximal. Specifically, in the lower limb region, the pressure gradually decreases from the ankle to the thigh. This pressure stimulates vascular endothelial cells to release vasoactive substances such as nitric oxide, effectively promoting the centripetal return of venous blood and lymph, thereby improving local and even systemic blood circulation efficiency, accelerating the clearance of exercise metabolic waste, and significantly reducing muscle fatigue and post-exercise soreness.

[0070] This gradient compression design can alleviate physiological stress responses such as edema caused by high altitude or low pressure environments. By tightly wrapping the muscles with gradient compression, it effectively limits unnecessary vibrations of the muscles during exercise. Especially during high-speed or high-impact activities, it further saves energy consumption and significantly reduces the risk of muscle injury, thereby improving athletic performance and safety.

[0071] The inner layer is a thermoplastic inner layer made of hot-pressed material. When the wearer performs daily activities, walking, mountain climbing, or breathing (expansion and contraction of the chest and abdomen), the pressure applied by the outer layer, as well as the dynamic friction and stretching between the fabric and the body, will directly act on the thermoplastic inner layer. This force is efficiently converted into mechanical stress on the thermoplastic ceramic particles, PVDF polymer matrix, and TPU synergistic matrix inside the thermoplastic composite fiber through the deformation amplification effect of the three-dimensional coil structure and porous structure. This mechanical stress stimulates the piezoelectric effect of the thermoplastic ceramic particles and PVDF, generating a local micro electric field. Furthermore, the micro electric field further induces the polarization and orderly arrangement of TPU molecular chains, synergistically enhancing the thermoplastic effect of the composite material.

[0072] Thus, the wearer's own mechanical movement energy is efficiently captured and converted into heat energy, and rapidly conducted to the surface in direct contact with the skin through a continuous heat-conducting network constructed by the heat-conducting filler, providing the body with immediate and continuous heat replenishment. This active heat generation mechanism complements traditional passive heat preservation methods. Especially in extremely cold environments, when the body's own metabolic heat production is insufficient to maintain core body temperature, the active heat replenishment capability of this invention can significantly improve the wearer's thermal balance and effectively reduce the risk of hypothermia caused by low-temperature exposure.

[0073] This invention provides an extremely cold-resistant down jacket fabric, comprising a double-layer composite structure consisting of a heat-pressing inner layer and a compression outer layer. The heat-pressing inner layer and the compression outer layer are tightly integrated, wherein the heat-pressing inner layer is disposed inside the compression outer layer. When the wearer moves, the pressure applied by the compression outer layer and its own deformation enable the active conversion and conduction of mechanical energy into heat energy.

[0074] This invention provides an extremely cold-resistant down jacket fabric that combines materials science, structural engineering, and biomechanical design to effectively capture, efficiently convert, and actively replenish the mechanical energy of the human body, achieving passive insulation, heat provision, and protective performance. The invention features a double-layer structure, with a pressurized inner layer and a compressed outer layer tightly integrated. The pressurized inner layer is located inside the compressed outer layer. When the wearer engages in daily or strenuous exercise, the wearer's breathing causes significant fluctuations in the abdomen and chest, allowing the preset pressure applied by the compressed outer layer and the deformation of the inner layer to work together efficiently. This initiates and amplifies the active conversion and conduction of mechanical energy into heat energy, providing responsive heat replenishment for the human body.

[0075] In a preferred embodiment of the present invention, the pressurized inner layer is woven from pressurized composite fibers, wherein the pressurized composite fibers include pressurized ceramic particles, polyvinylidene fluoride (PVDF) polymer matrix, thermoplastic polyurethane (TPU) synergistic matrix, and thermally conductive filler.

[0076] The piezoelectric ceramic particles mentioned above are preferably barium titanate (BaTiO3) particles with an average particle size of 50 nm to 200 nm and a tetragonal crystalline structure. Their excellent dielectric and piezoelectric properties, acting as piezoelectric active centers, enable charge separation under mechanical stress. The tetragonal crystalline structure of the barium titanate particles ensures piezoelectric response on a macroscopic scale.

[0077] Polyvinylidene fluoride (PVDF) polymer matrix, with a weight-average molecular weight range of 200,000 to 500,000, has a high content of piezoelectric active β phase. Its piezoelectric response is improved by mechanical stretching or strong electric field polarization treatment. The β phase content of the polymer matrix can further enhance its piezoelectric effect and provide a stable dispersion medium and mechanical conduction path for barium titanate particles. Moreover, the specific weight-average molecular weight range optimizes the processing flowability and the mechanical strength of the final fiber.

[0078] Thermoplastic polyurethane (TPU) matrix, with a Shore hardness range of 80A to 95A, is composed of soft and hard segments to provide excellent elasticity, toughness, and molecular chain polarizability. The soft segments are polyether polyols or polyester polyols, while the hard segments are products of the reaction between diisocyanate and chain extender. The soft and hard segments endow this material with excellent elasticity, toughness, and crucial molecular chain polarizability. The soft segments of TPU provide the necessary flexibility, while the hard segments ensure mechanical strength and the ability of molecules to arrange themselves in an orderly manner. Under the induction of an external electric field, dipoles can be redirected and rearranged.

[0079] The thermally conductive filler is preferably sheet-like graphene or carbon nanotubes, with the following size distribution: the graphene sheet thickness is less than 10 nm and the lateral dimension is 1 to 10 micrometers; the carbon nanotube diameter is 5 to 50 nm and the length is 1 to 10 micrometers. The volume fraction of the thermally conductive filler in the compressive heat treatment composite fiber is 5% to 15%, aiming to construct an efficient thermally conductive network. Through its own high aspect ratio or large specific surface area characteristics, it ensures that an efficient and continuous thermally conductive network can be formed inside the composite material, thereby ensuring that the heat generated by the compressive heat treatment effect can be quickly dissipated.

[0080] Specifically, pressure-heated ceramic particles, polyvinylidene fluoride polymer matrix, thermoplastic polyurethane synergistic matrix, and thermally conductive filler are uniformly dispersed through melt blending or solution blending techniques to prepare a pressure-heated composite material.

[0081] In this composite material, the compressive heating ceramic particles and the polyvinylidene fluoride (PVDF) polymer matrix generate a weak local electric field under mechanical pressure. This electric field acts on the polar molecular chains of the thermoplastic polyurethane (TPU) synergistic matrix, causing the dipoles of the TPU molecular chains to orient, align in an ordered manner, and / or inducing local molecular chain conformational changes. This synergistically enhances the compressive heating effect of the composite material, allowing it to release more significant heat through entropy reduction under less mechanical pressure. The entropy reduction mechanism of the compressive heating effect lies in the fact that when external mechanical pressure acts on the composite material, especially on the TPU molecular chains and the internally doped PVDF / BaTiO3 structure, the conformational freedom of the polymer chain segments decreases, and the arrangement tends to become more ordered, thus causing a decrease in the entropy of the system. According to Gibbs free energy and the first law of thermodynamics, under adiabatic or near-adiabatic compression conditions, when the entropy decreases, the system releases heat to the environment, realizing the conversion of mechanical energy into thermal energy.

[0082] Furthermore, during the weaving process to form the inner layer of the pressure-heat composite fiber, it is woven in a three-dimensional coil structure. Specifically, it is formed by weft knitting or warp knitting techniques to create a loop structure or spiral structure with high elastic deformation capability. The coil diameter is 0.5 mm to 2 mm, and the coil density is 200 to 500 coils per square centimeter. The three-dimensional coil structure can produce significant macroscopic deformation when subjected to slight mechanical pressure, thereby effectively amplifying the stress transmitted to the interior of the pressure-heat composite material, and thus activating and enhancing the pressure-heat effect.

[0083] Furthermore, the pressurized inner layer is designed with a porous structure during the preparation process, with a porosity of 30% to 60% and an average pore size ranging from 50 micrometers to 200 micrometers. The porous structure is prepared by introducing a pore-forming agent during the spinning process of the pressurized composite material and then removing it. When the porous structure is under pressure, the bending, compression, and collapse of the pore walls can further promote greater conformational changes and entropy reduction in the molecular chains inside the pressurized composite fiber, thereby converting external mechanical pressure into heat more efficiently.

[0084] The heat-conducting filler forms a continuous heat-conducting path in the compressive heat composite fiber, which enables the heat generated by the compressive heat effect to be effectively conducted from the inside of the material to the wearer's body, thereby avoiding the accumulation of heat inside the material and achieving effective heating for the wearer.

[0085] In a preferred embodiment of the present invention, the compression outer layer is made of a high-elasticity blended material, an aerogel insulation material, and a waterproof and breathable membrane material. The high-elasticity blended material is made of a blend of nylon / spandex or polyester / spandex fibers, wherein the mass fraction of spandex is 15% to 30%, and the mass fraction of nylon or polyester is 70% to 85%. The elastic modulus of the blended fabric is precisely controlled to achieve a preset gradient compression effect. The high-elasticity blended material is respectively disposed on the down jacket fabric from the distal end to the proximal end of the limb to provide decreasing compression pressure, with the pressure range being 20 mmHg to 30 mmHg at the distal end of the limb and 10 mmHg to 15 mmHg at the proximal end of the limb. Specifically, the distal end of the limb refers to the lower leg and forearm area, and the proximal end of the limb refers to the thigh and upper arm area. Gradient compression design optimizes blood circulation efficiency in the lower and upper limbs while maintaining wearing comfort by adjusting the fabric's weave density, fiber thickness, and structural pattern. This promotes the return of venous blood and lymph to the heart, effectively reduces muscle fatigue, and provides muscle support to reduce movement-induced vibrations.

[0086] Furthermore, the aerogel insulation material is composed of flexible aerogel felt or aerogel composite fibers with a thickness of 1 mm to 3 mm and an effective thermal conductivity of less than 0.02 W / m·K. The aerogel insulation material is encapsulated inside a highly elastic blended material to form discrete or continuous heat-insulating units. The encapsulation technology is preferably microencapsulation or lamination technology to ensure the stability of the aerogel structure and its insulation performance. Through its unique nanoscale porous structure, the aerogel insulation material greatly restricts the conduction and convection of gas molecules, thereby effectively blocking heat loss and providing excellent passive insulation performance.

[0087] Furthermore, the preferred waterproof and breathable membrane material is a polyurethane (PU) film with a thickness of 15 to 50 micrometers. The PU film has a microporous or hydrophilic non-microporous structure, with a static water pressure resistance greater than 20,000 mm H2O and a water vapor transmission rate (MVTR) greater than 20,000 g / m² / 24h. The waterproof and breathable membrane material is bonded to the outer surface of a highly elastic blended material through lamination or coating, providing excellent waterproof and windproof properties for down jacket fabrics while allowing sweat to escape as water vapor, keeping the wearer dry and comfortable.

[0088] Example 1:

[0089] First, in the preparation stage of the pressure-heat composite material, tetragonal barium titanate (BaTiO3) particles with an average particle size of 100 nm were selected. The PVDF polymer matrix used was Kynar® 720, a commercially available brand with a weight-average molecular weight of 350,000, whose initial β-phase content was pretreated to reach 60%. The TPU synergistic matrix used was Desmopan® 3090A, with a Shore hardness of 90 A. The thermally conductive filler was sheet-like graphene with a transverse dimension of 5 μm and a thickness of 5 nm.

[0090] The specific mass ratio of each component is as follows: BaTiO3 particles account for 5% of the mass of PVDF, TPU particles account for 20% of the mass of PVDF, and graphene filler accounts for 10% of the mass of PVDF. The mixture is melt-blended in a twin-screw extruder (ZSK 26MC) manufactured by Coperion GmbH, Germany, at a temperature of 200°C, a screw speed of 150 rpm, and an L / D ratio of 40, to obtain uniform thermocomposite material particles.

[0091] Secondly, in the hot-pressed composite fiber spinning stage, the aforementioned composite material particles are spun into fibers with a linear density of 150 denier using melt spinning equipment. The spinning temperature is controlled at 220°C, the draw ratio is set at 3.5:1, and the air velocity in the cooling zone is 2 m / s. After spinning, the fibers undergo two stages of mechanical stretching on heated rollers at 120°C, with a total stretch ratio of 4 times, ensuring that the β phase content in PVDF is increased to over 85%.

[0092] Next, in the heat-pressed inner layer weaving stage, an HKS 3-M high-speed warp knitting machine manufactured by Karl Mayer, Germany, was used to weave the heat-pressed composite fibers into a fabric with a three-dimensional loop structure. The weaving parameters were set as follows: loop diameter 1 mm, loop density 350 loops per square centimeter. To form a porous structure, polyethylene glycol (PEG, molecular weight 4000) was added at 15% of the total mass of the composite material before spinning. This PEG was removed after weaving by washing with 70°C warm water, resulting in a final fabric porosity of 45% and an average pore size of 120 micrometers. The fabric's thermal conductivity was tested to reach 7.2 W / m·K.

[0093] In the preparation stage of the compression outer layer, the high-elasticity blended material uses a blended yarn of 25% spandex (InvistaLycra®) and 75% nylon 6 (Dupont Tactel®) by mass, knitted on a GL616 circular knitting machine manufactured by Lonati, Italy. At the distal end of the limb (lower leg area), the knitting density is set at 28 stitches / inch, the yarn tension is 1.5 cN, and a compression pressure of 25 mmHg is provided; at the proximal end of the limb (thigh area), the knitting density is set at 24 stitches / inch, the yarn tension is 1.0 cN, and a compression pressure of 12 mmHg is provided. The aerogel insulation material is a 2 mm thick flexible silicone aerogel felt (Aspen Aerogels Pyrogel® XTE), which is fixed to the inner side of the high-elasticity blended material by hot pressing (150℃, 0.5 MPa, 30 seconds). The waterproof and breathable membrane material is a 25-micron thick hydrophilic non-microporous polyurethane (PU) film (Sympatex® Moisture-Tech), which is laminated to the outer surface of the high-elasticity blended material by a wet lamination process. Its MVTR reaches 25000 g / m² / 24h, and its static water pressure resistance reaches 25000 mm H2O.

[0094] Finally, in the double-layer composite and integration stage, the heat-pressed inner layer and the compressed outer layer are made of high-strength polyester thread and sewn together using a 745 flatlock industrial sewing machine manufactured by Dürkopp Adler GmbH in Germany, to ensure that the two layers are tightly packed and the seams are smooth.

[0095] The performance of the extreme cold-resistant down jacket fabric prepared in this embodiment was tested:

[0096] In a simulated extreme cold environment (-20℃), the wearer walked on a treadmill at a speed of 6 km / h for 30 minutes. A high-precision heat flow sensor (Hukseflux HFP01) measured the heat flow on the fabric surface in contact with the skin, while near-infrared spectroscopy (NIRS) monitored changes in calf muscle oxygenation and blood flow. Results showed that the fabric continuously generated an average of 25 W / m² of active heat during the wearer's exercise, and this heat was effectively transferred to the skin surface by the heat flow sensor. Compared to the resting state, muscle blood flow in the calf area increased by 15%, muscle oxygenation increased by 10%, and lactic acid accumulation slowed by 20%. The wearer subjectively reported feeling comfortable, warm, and without significant fatigue.

[0097] Comparative Example 1:

[0098] This comparative example prepares a mainstream high-performance extreme cold down jacket fabric for comparison. This fabric adopts a traditional three-layer structure design, which aims to provide excellent passive insulation and protection, but lacks active heat generation and gradient compression functions.

[0099] The outer layer of the contrast fabric is made of high-density ripstop nylon with a durable water-repellent (DWR) finish, weighing 150 g / m² and exhibiting a static water pressure resistance of 15,000 mmH₂O. The middle layer is a down-filled layer using goose down with a fill power of 850 FP, at a density of 300 g / m², with an overall thickness of approximately 20 mm. The inner layer is a microfiber lining, weighing 60 g / m², providing a soft touch. The fabric has an overall thermal resistance (Clo value) of 6.5, but its operation is entirely based on the insulation properties of the down layer. This fabric does not contain piezoelectric / pressure-thermal materials and is not designed with a gradient compression structure.

[0100] The comparative fabric underwent the same performance tests as in Example 1:

[0101] In a simulated extreme cold environment (-20℃), the wearer walked on a treadmill at a speed of 6 km / h for 30 minutes. High-precision heat flow sensors were used to measure the surface heat flow of the fabric in contact with the skin, and near-infrared spectroscopy was used to monitor changes in calf muscle oxygenation and blood flow. The results showed that the control fabric did not generate any measurable active heat during the test; the surface heat flow relied entirely on the wearer's own metabolic heat production. Muscle blood flow in the calf area showed no significant change compared to the resting state, muscle oxygenation levels did not increase, and the rate of lactic acid accumulation did not slow down. The wearer subjectively felt warm at the beginning of exercise, but as the exercise time increased, due to the lack of active heat replenishment, especially with changes in exercise intensity, the perceived temperature fluctuated significantly, and a slight feeling of fatigue appeared in the calf area.

[0102] By comparing and analyzing the test results of Example 1 and Comparative Example 1, the significant advantages of the fabric of the present invention in terms of active heat generation, physiological efficiency optimization, and overall comfort can be clearly observed. The present invention converts the mechanical kinetic energy of the human body into heat energy through a compressed inner layer, effectively solving the problem of insufficient heat supply in extreme environments by traditional passive insulation fabrics. At the same time, the positive impact of the compressed outer layer on blood circulation surpasses the single protective capability of existing technologies.

[0103] Table 1 provides a detailed comparison of the key performance indicators between Example 1 and Comparative Example 1.

[0104] Table 1

[0105] Performance indicators Example 1 Comparative Example 1 <![CDATA[Active heat generation (W / m 2 ).]]> 25 0 Overall thermal resistance (Clo) 6.8 6.5 Increase in blood flow (%) 15 0 Muscle oxygenation increased (%) 10 0 Lactate accumulation slowed down (%) 20 0 <![CDATA[Static hydrostatic resistance (mm H2O)]]> 25000 15000 <![CDATA[Water vapor transmission rate (g / m 2 / 24h)]]> 25000 12000 Total fabric thickness (mm) 5 20

[0106] As shown in Table 1, the fabric of this invention achieves active heat generation while maintaining static thermal insulation performance comparable to or even superior to traditional high-performance fabrics, and exhibits significant optimization effects on physiological indicators such as blood flow, muscle oxygenation, and lactic acid accumulation. Furthermore, its superior waterproof and breathable properties and lighter structure further enhance the wearer's comfort and convenience during exercise. These quantitative data fully demonstrate the revolutionary progress brought about by this invention in the field of extreme cold-resistant down jacket fabrics, effectively overcoming the limitations of existing technologies in heat management and physiological efficiency maintenance under extreme environments.

[0107] Experiment 2:

[0108] Example 1 was used as the control group for preparation. Several experimental groups were prepared by varying the piezoelectrically active β-phase content and the porosity of the porous structure in the polyvinylidene fluoride (PVDF) polymer matrix of Example 1. The β-phase content was controlled by adjusting the stretching ratio of the PVDF polymer matrix, specifically the ratio of the stretched fiber length to the original length. The β-phase content was obtained by Fourier transform infrared spectroscopy (FTIR). Specifically, the prepared thermoplastic composite fiber sample was placed in an FTIR spectrometer and its absorption spectrum within a specific wavenumber range was obtained. The specific wavenumber range for the β-phase was located at 1270 cm⁻¹. -1 and 840 cm -1 Porosity is the proportion of pore volume to total volume in a material. This is determined by precisely cutting a regularly shaped sample from the prepared fabric, measuring its thickness and area with a micrometer to calculate its total volume, weighing the sample (m) using a balance, and consulting existing literature to determine its density. Porosity was calculated, where m is the mass of polyvinylidene fluoride (PVDF), V is the volume of PVDF, and ρ is the density of PVDF. Fabrics prepared for both the experimental and control groups were fitted onto a stretching mechanism to simulate the compression exerted on the fabric by the contraction and expansion of the chest and abdomen during exhalation in the human body during exercise. Simultaneously, a heat flow sensor was placed on the inner side of the fabric to capture the generated heat in real time. See Table 2 for details.

[0109] Table 2

[0110] stretch ratio β phase content (%) Porosity (%) <![CDATA[Heat generation (W / m 2 ).]]> Control Group 1 4 60 45 25 Experimental Group 1 3 51 45 16 Experimental Group 2 5 67 45 19 Experimental Group 3 4 60 30 16 Experimental Group 4 4 60 60 17

[0111] As shown in Table 2, the piezoelectric active β phase content and the porosity of the porous structure in the polyvinylidene fluoride (PVDF) matrix synergistically affect the heat conversion of the pressurized inner layer. The piezoelectric effect of PVDF does not originate from all its crystalline phases, but mainly from the β crystalline phase in which its molecular chains are in an all-trans conformation and the dipole moments are aligned in the same direction. In the preparation process, the change in the β phase content is controlled by controlling the degree of mechanical stretching in the second step. Essentially, this is to make the dipoles in the PVDF molecular chains highly oriented. When the subsequent movement of the wearer causes the fabric to deform under pressure, it is these highly ordered β phase crystal structures that convert mechanical stress into a small local electric field.

[0112] The in-situ generated electric field acts as a switch to trigger the entire pressure-thermal effect. It acts on the TPU matrix, forcing the polar groups in the TPU molecular chains to orient and rearrange, thereby reducing the system's entropy. According to the laws of thermodynamics, this entropy reduction process converts mechanical energy into thermal energy by releasing heat. Therefore, if the β-phase content is insufficient, even with significant mechanical stress, the electric field required to drive the TPU entropy reduction cannot be effectively generated, leading to the failure of the energy conversion source and ultimately a significant reduction in heat generation.

[0113] The porous structure formed by introducing a pore-forming agent into the inner layer of the pressure heat treatment directly determines the fabric's ability to capture and amplify external mechanical stress, i.e., the efficiency of energy input. This three-dimensional coil and the porous structure together constitute an ingenious mechanical amplification system. When the wearer moves, the pressure applied by the outer layer and the friction between the body and the fabric first act on this macroscopic structure.

[0114] High porosity means that the material has more and more deformable pores and elastic coils inside. When under pressure, the bending and collapse of these pore walls and the tensile deformation of the coils can efficiently concentrate and transform the relatively weak macroscopic pressure widely distributed on the fabric into intense local stress acting on each thermoplastic composite fiber. This is equivalent to amplifying a gentle press into thousands of impacts on the microstructure inside the fiber. If the porosity is too low and the fabric structure is too dense and rigid, the deformation ability is poor, and most of the external mechanical energy will be elastically stored or dissipated, and cannot be effectively transferred to the PVDF / BaTiO3 piezoelectric unit to excite the electric field, resulting in a large amount of kinetic energy being wasted and unable to be used for heat generation.

[0115] In summary, the β-phase content and porosity, at both the microscopic and macroscopic scales, synergistically regulate the performance of the pressurized inner layer. The β-phase content determines how much mechanical energy can be converted into electrical energy, ultimately leading to entropy reduction and heat generation; while the porous structure acts as the "capture and amplification" hub for energy, determining how much mechanical energy from human movement can be effectively input into the system. If the β-phase content is low, the conversion efficiency is low, and the captured energy cannot effectively generate heat; if the porosity is insufficient, the energy capture efficiency is low, and the available mechanical energy for conversion is insufficient. Ultimately, deficiencies in either will lead to the same result: the supplementary heat generated by the pressurized inner layer under pressure is significantly reduced, making it impossible to achieve the design goal of relying on human movement for autonomous heat generation in extremely cold environments.

[0116] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing an extremely cold-resistant down jacket fabric, characterized in that, Includes the following steps: S1: A pressure-heated composite material is prepared by mixing pressure-heated ceramic particles, polyvinylidene fluoride polymer matrix, thermoplastic polyurethane synergistic matrix and thermally conductive filler. S2: The compressive heat composite material prepared in S1 is spun into compressive heat composite fiber and subjected to mechanical stretching or electric field polarization treatment. S3: The pressure-heating composite fibers treated with S2 are woven into a pressure-heating inner layer with a three-dimensional coil structure and a porous structure; S4: High-elasticity blended materials, aerogel insulation materials and waterproof and breathable membrane materials are laminated to form a compressed outer layer; S5: The pressurized inner layer prepared in S3 and the compressed outer layer prepared in S4 are tightly integrated and composited, with the pressurized inner layer placed inside the compressed outer layer.

2. The extremely cold-resistant down jacket fabric and its preparation method according to claim 1, characterized in that: In S1, the pressure-heated ceramic particles are tetragonal barium titanate particles with a particle size of 50 nm to 200 nm; the polyvinylidene fluoride polymer matrix has a weight-average molecular weight of 200,000 to 500,000 and has a piezoelectric active β phase content of 50% to 70%; the thermoplastic polyurethane synergistic matrix has a Shore hardness of 80 A to 95 A; and the thermally conductive filler is sheet-like graphene or carbon nanotubes with a volume fraction of 5% to 15%.

3. The extremely cold-resistant down jacket fabric and its preparation method according to claim 1, characterized in that: In S1, the pressure-heated ceramic particles account for 3%-7% of the mass of the polyvinylidene fluoride (PVDF) polymer matrix, the thermoplastic polyurethane synergistic matrix accounts for 10%-30% of the mass of the PVDF polymer matrix, and the thermally conductive filler accounts for 5%-15% of the mass of the PVDF polymer matrix. The mixture is prepared by using a twin-screw extruder at 180-220°C and a screw speed of 100-200 rpm.

4. The extremely cold-resistant down jacket fabric and its preparation method according to claim 1, characterized in that: In S2, the hot-pressed composite fiber spinning process includes controlling the spinning temperature at 200-400℃, the draw ratio at 2-5:1, and the linear density at 100-200 denier; the mechanical stretching temperature at 100-1140℃, the stretching ratio at 3-5 times the original fiber length, and the electric field polarization electric field strength at 10-30kV / mm.

5. The extremely cold-resistant down jacket fabric and its preparation method according to claim 1, characterized in that: In S3, the hot-pressed inner layer weaving includes forming a three-dimensional coil structure with a coil diameter of 0.5mm-2mm and a coil density of 200 to 500 coils per square centimeter through weft knitting or warp knitting techniques; the porous structure has a porosity of 30% to 60% and an average pore size of 50 to 200 micrometers.

6. The extremely cold-resistant down jacket fabric and its preparation method according to claim 1, characterized in that: In S4, the high-elasticity blended material is selected from 15%-30% spandex fiber and 70%-85% nylon fiber by mass. The aerogel insulation material is a flexible silicone aerogel felt with a thickness of 1-3 mm, a lamination and encapsulation temperature of 100-200℃, and a pressure of 0.1-1.0 MPa; the waterproof and breathable membrane material is a polyurethane film with a thickness of 15-50 μm, and in S5, the composite temperature is 120-140℃.

7. A cold-resistant down jacket fabric, comprising a double-layer composite structure, characterized in that: The double-layer composite structure comprises a heat-pressing inner layer and a compression outer layer; The pressurized inner layer is disposed inside the compression outer layer; When the wearer moves, the inner heat-pressurizing layer can actively convert and conduct mechanical energy into heat energy through the pressure applied by the outer compression layer and its own deformation.

8. The extremely cold-resistant down jacket fabric according to claim 7, characterized in that: The inner layer of the pressure heating is woven from pressure heating composite fibers. The core components of the pressure heating composite fibers include pressure heating ceramic particles, polyvinylidene fluoride (PVDF) polymer matrix, thermoplastic polyurethane (TPU) synergistic matrix, and thermally conductive filler. The pressure heating ceramic particles are barium titanate (BaTiO) particles with a tetragonal crystalline structure.

9. The extremely cold-resistant down jacket fabric according to claim 8, characterized in that: The compressed outer layer comprises a highly elastic blended material, an aerogel insulation material, and a waterproof and breathable membrane material.

10. The extremely cold-resistant down jacket fabric according to claim 9, characterized in that: The pressurized composite fibers in the pressurized inner layer are woven into a three-dimensional coil structure. The three-dimensional coil structure can produce significant macroscopic deformation when subjected to slight mechanical pressure, thereby effectively amplifying the stress transmitted to the interior of the pressurized composite material.

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