Ultrafine polymer porous fiber and preparation method and application thereof

Abstract

The present invention relates to an ultrafine polymer porous fiber, a preparation method thereof and an application thereof, belonging to the technical field of polymer foamed fibers and their processing. The diameter of the ultrafine polymer porous fiber provided by the present invention is 0.05 mm - 0.21 mm, and the density is 0.20 g / cm<supgt;3< / supgt> - 1.00 g / cm<supgt;3< / supgt>; the cells inside the ultrafine polymer porous fiber are spindle-shaped, and the size distribution range of the transverse cross-section of the cells is 0.5 μm - 20 μm, and the size distribution range of the radial cross-section is 5 μm - 80 μm. The ultrafine polymer porous fiber of the present invention has a closed-cell structure and contains cells inside. The cell sizes are uniform. The spindle-shaped cell structure enables a wider pore size distribution range, which can achieve better thermal management performance. At the same time, the ultrafine polymer porous fiber has a small diameter, low density, higher strength and stronger spinnability, and has excellent thermal insulation performance, and can be applied in the fields of yoga clothes, thermal underwear, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of high molecular polymer foamed fibers and processing thereof, and specifically relates to an ultrafine polymer porous fiber and a preparation method and application thereof. Background Art

[0002] Polymer porous fiber specifically refers to fiber materials with a certain pore structure, which can be used in various fields such as textile, medical, and industry. It also has the performance characteristics of the pore structure and exhibits more excellent performance: low density, high elasticity, high flexibility, etc., further expanding its application areas.

[0003] At present, the process of using supercritical CO2, N2 or other mixed gases as foaming agents to achieve continuous thermoplastic elastomer foaming materials in patent CN117646339A has been fully verified. The physical foaming fibers produced have basic properties such as uniform strands and complete pore structure, and can be applied to industrial textiles. However, for textiles that can be used for clothing, the thermoplastic elastomer foaming fibers obtained by the current preparation process have a relatively thick diameter and are not soft enough. Although they can be used for certain industrial production, they still have certain limitations in the field of textiles and clothing.

[0004] Therefore, in order to improve the spinnability of polymer foam fibers and expand their application range, it is of great significance to develop an ultrafine polymer porous fiber. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and to provide an ultrafine polymer porous fiber and a preparation method and application thereof.

[0006] The present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides an ultrafine polymer porous fiber, wherein the diameter of the ultrafine polymer porous fiber is 0.05 mm-0.21 mm and the density is 0.20 g / cm 3 -1.0g / cm 3 The pores inside the ultrafine polymer porous fiber are spindle-shaped, and the size distribution range of the transverse section of the pores is 0.5μm-20μm, and the size distribution range of the radial section is 5μm-80μm.

[0008] The ultrafine polymer porous fiber of the present invention is a closed-cell structure, and contains pores inside, the pore size is uniform, and the spindle-shaped pore structure makes the pore size distribution range wider, which can achieve better thermal management performance. At the same time, the diameter of the ultrafine polymer porous fiber can be evenly controlled between 0.07mm-0.21mm and has a low density. The porous fiber has a thinner diameter, higher strength, and stronger spinnability, and has excellent thermal insulation performance, and can be used in yoga clothes, thermal clothing and other fields.

[0009] Preferably, the ultrafine polymer porous fiber comprises the following components by weight: 80-100 parts of polymer, 1-15 parts of nucleating agent, 0.1-1 parts of chain extender, 0-0.5 parts of antioxidant, 0.1-0.2 parts of softener, and 0-2 parts of antistatic agent.

[0010] More preferably, the ultrafine polymer porous fiber comprises the following components by weight: 90-95 parts of polymer, 1-13 parts of nucleating agent, 0.1-0.2 parts of chain extender, 0.2-0.5 parts of antioxidant, 0.1-0.2 parts of softener, and 1-2 parts of antistatic agent.

[0011] Adding chain extenders to the components and adaptively adding softeners can effectively improve the flexibility and viscosity of the polymer, making it easier to process.

[0012] Preferably, the polymer has a melting point of 140°C-250°C and a hardness of 40D-85D.

[0013] Preferably, the polymer includes at least one of a thermoplastic elastomer, a polyester, and a polyamide; more preferably, the thermoplastic elastomer includes at least one of a thermoplastic polyurethane elastomer (TPU), a polyester elastomer (TPEE), and a nylon elastomer (PEBA); the polyester includes at least one of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polytrimethylene terephthalate (PTT); and the polyamide includes at least one of nylon 6 (PA6), nylon 66 (PA66), nylon 11 (PA11), and nylon 12 (PA12).

[0014] Preferably, the nucleating agent includes at least one of calcium carbonate, carbon black, nano-TiO2, montmorillonite, nano-silicon dioxide, carbon nanotubes, and PTFE powder.

[0015] Preferably, the chain extender comprises at least one of a difunctional acid derivative, an isocyanate, an anhydride and an epoxide.

[0016] Preferably, the antioxidant includes at least one of an amine antioxidant and a phosphorus antioxidant.

[0017] Preferably, the average particle size of the nucleating agent is 0.05 μm-3 μm.

[0018] Preferably, the softener includes at least one of a silicone softener, a cationic softener, a nonionic softener, and a composite softener.

[0019] Preferably, the antistatic agent comprises a hydrophobic antistatic auxiliary agent.

[0020] In a second aspect, the present invention provides a processing device for the ultrafine polymer porous fiber, which comprises in sequence: a wire feeding unit, a heat insulation unit, a micro-extrusion heating unit, a micro-extrusion die, and three groups of heating and drawing units.

[0021] The wire feeding unit described in the present invention is responsible for stably feeding the polymer wire treated with supercritical fluid into the micro-extrusion foaming system. The wire feeding unit uses rotating gears as power. The gears of the wire feeding unit need to have a good extrusion force on the polymer. The gears are not easy to wear during long-term use. Preferably, the gears of the wire feeding unit are made of hard aluminum, stainless steel, alloy steel, etc.

[0022] The heat insulation unit can prevent the heat of the heating unit from being transferred to the wire feeding unit, so that the wire material becomes significantly softer and affects the stability of wire feeding. The temperature after cooling by the heat insulation unit is not greater than the softening temperature of the polymer wire material or the impregnated polymer wire material. Preferably, the heat insulation unit is provided with an aluminum part with a groove structure and an active cooling device with a fan.

[0023] The micro-extrusion heating unit can quickly heat the polymer filaments, so that the polymer system transitions from a glassy state to a highly elastic state and a viscous flow state, and cell nucleation and rapid cell growth occur.

[0024] Preferably, the heating and stretching unit comprises a heating tunnel and a pulling roller.

[0025] The heating and stretching unit mainly adopts a post-stretching process, and the polymer porous fibers that have been shaped by the first group of heating and stretching units are heated and stretched in the second hot tunnel, and then preheated by a stretching roller, and heated again in the next hot tunnel, and stretched by a stretching roller, so that ultrafine polymer porous fibers can be obtained without sacrificing their pore structure. By controlling the heating temperature, processing speed, etc., the stretching ratio can be controlled to obtain thermoplastic elastomer foamed fibers with different diameters.

[0026] In a third aspect, the present invention provides a method for preparing the ultrafine polymer porous fiber, comprising the following steps:

[0027] S1, premixing all components, melt extruding, drying, winding, and impregnating supercritical fluid to obtain polymer filaments;

[0028] S2, heating and foaming the polymer filament obtained in step S1, shaping it in a channel, and stretching it at a constant speed to obtain polymer foamed fibers;

[0029] S3, heating and stretching the polymer foamed fiber obtained in step S2, heating again, and stretching again to obtain the ultrafine polymer porous fiber.

[0030] The preparation method of the present invention adds a drawing unit on the basis of micro-extruded foamed fibers, so that the polymer foamed fibers are drawn to a finer diameter without sacrificing the cell structure, and the strength thereof is increased with the drawing action, so that the fibers are more spinnable. In the preparation method of the present invention, there is no high extrusion system pressure, the polymer foaming occurs during the micro-extrusion foaming process, and through the post-drawing process, the multi-stage temperature and speed control staggered setting is used to obtain ultra-fine polymer foamed fibers with a finer diameter, higher strength, and stronger spinnability. The processing process is gentle, and large-scale continuous production can be achieved.

[0031] When preparing ultrafine polymer porous fibers, the polymer foamed fibers obtained on the basis of step S2 need to be subjected to two more heat stretchings to obtain ultrafine polymer porous fibers. If only one post-stretching is performed, the pore structure in the porous fiber will be regarded as a defect during the stretching deformation process, thereby inducing macroscopic fracture of the fiber. Therefore, the post-stretching must adopt a two-time heat stretching combination process, wherein the first heat stretching at a relatively low temperature has the effect of inducing the system tensile deformation mainly to occur in the pore deformation while maintaining the strength of the cortical matrix, and the second heat stretching at a relatively high temperature mainly has the effect of eliminating the stress in the cortex and further stretching to reduce the diameter of the porous fiber.

[0032] Preferably, in the step S1, the melt extrusion is performed using a twin-screw extruder, and the temperature of the melt extrusion is 250°C-320°C.

[0033] Preferably, in step S1, the supercritical fluid is CO2 fluid, N2 fluid or a mixed fluid of CO2 fluid and N2 fluid.

[0034] Preferably, in the step S1, the solubility of the supercritical fluid in the polymer filament is 0.5wt%-7.0wt%; more preferably, the solubility of the supercritical fluid in the polymer filament is 1.0wt%-6.0wt%.

[0035] Preferably, in the step S1, all the components are dried by hot air after being premixed, and the moisture content of the materials after drying is less than 0.05%.

[0036] Preferably, in step S2, the wire feeding speed when heating and foaming the polymer wire obtained in step S1 is 50 mm / s-100 mm / s; more preferably 70 mm / s-100 mm / s.

[0037] Preferably, in step S2, the temperature of the heating and foaming is 200°C-380°C, and the residence time is 0.3s-3.0s; more preferably, the temperature of the heating and foaming is 280°C-320°C, and the residence time is 0.5s-2.0s.

[0038] Preferably, in step S2, the temperature of the tunnel shaping is 140°C-270°C, and the residence time in the tunnel is 0.1s-2.0s.

[0039] Preferably, in step S2, the speed of the constant speed stretching is 1 m / min-8 m / min; more preferably, the speed of the constant speed stretching is 3 m / min-5 m / min.

[0040] Preferably, in step S2, the diameter of the polymer foam fiber is 0.1 mm-0.5 mm.

[0041] Preferably, in step S3, the heating temperature is 20°C-80°C; more preferably, in step S3, the heating temperature is 30°C-60°C.

[0042] Preferably, in step S3, the stretching temperature is 30°C-150°C, and the line speed is 3m / min-50m / min; more preferably, the stretching temperature is 60°C-120°C, and the line speed is 9m / min-25m / min.

[0043] Preferably, in step S3, the reheating temperature is 80°C-150°C; more preferably, the reheating temperature is 100°C-120°C.

[0044] Preferably, in step S3, the temperature of the re-stretching is 10°C-100°C, and the line speed is 3m / min-250m / min; more preferably, the temperature of the re-stretching is 30°C-60°C, and the line speed is 4.5m / min-150m / min.

[0045] Preferably, in step S3, heating and reheating are performed using a hot tunnel, and stretching and re-stretching are performed using traction rollers.

[0046] In step S3, a two-stage heating and stretching combination is adopted to achieve multi-stage stretching. By adjusting the heating temperature and the stretching rate, it is possible to reduce the fiber diameter while ensuring its strength.

[0047] In a fourth aspect, the present invention provides the ultrafine polymer porous fiber, the method for preparing the ultrafine polymer porous fiber, and the application of the ultrafine polymer porous fiber in the fields of outdoor sportswear, functional clothing, and electronic wearable devices.

[0048] The ultrafine polymer porous fibers prepared in the present invention have an improved porous structure, and the fabric woven therefrom has excellent warmth retention performance, good elasticity, friction fastness, air permeability and moisture permeability, etc., and can be applied to outdoor sportswear, functional clothing, electronic wearable devices and other clothing fields.

[0049] The present invention has the following beneficial effects:

[0050] (1) The ultrafine polymer porous fiber of the present invention can continuously prepare a porous structure for a long time, and has the advantages of uniform thickness, excellent elastic tensile performance, low density, wear resistance, weavability, dense pore distribution, simple and easy preparation process, low cost, and green environmental protection.

[0051] (2) In the micro-extrusion foaming system of the ultrafine polymer porous fiber of the present invention, there is no high extrusion system pressure. The polymer foaming occurs in the micro-extrusion foaming process, and the nucleation and growth degree of the pores are controlled by controlling the residence time of the polymer in the micro-extrusion foaming process, so that the pore structure of the foamed fiber is uniform and the thickness of the foamed fiber is uniform.

[0052] (3) The post-stretching process of the ultrafine polymer porous fiber of the present invention mainly adopts heating to change its molten state, and the method of speed difference stretching is used to obtain ultrafine foamed fibers. The diameter of the foamed fibers is uniform and controllable, thereby improving the production stability of the micro-extruded foamed fibers. The processing process of the present invention is gentle and can realize large-scale continuous production.

[0053] (4) The ultrafine polymer porous fiber of the present invention can increase its spinnability and durability, and is more suitable for the textile field, and can be used for weaving various outdoor sportswear. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic diagram of the processing equipment of the ultrafine polymer porous fiber of the present invention;

[0055] Figure 2 This is a SEM photograph of the "spindle-shaped" cell structure of the ultrafine polymer porous fiber of Example 3 of the present invention;

[0056] Figure 3SEM photos of the ultrafine polymer porous fiber of Example 3 of the present invention and the polymer foamed fiber obtained in step S2; wherein, Figure a is a transverse cross-sectional view of the polymer foamed fiber, Figure b is a transverse cross-sectional view of the ultrafine polymer porous fiber, Figure c is a radial cross-sectional view of the polymer foamed fiber, and Figure d is a radial cross-sectional view of the ultrafine polymer porous fiber. DETAILED DESCRIPTION

[0057] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0058] Unless otherwise specified, the experimental methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0059] The materials used in the embodiments and comparative examples are as follows (the parts involving hardness all refer to Shore hardness):

[0060] Thermoplastic elastomer A (TPU):

[0061] A1: 45D, melting point 210°C, brand 58134, Lubrizol, USA.

[0062] A2: 60D, melting point 210°C, brand 58863, Lubrizol, USA.

[0063] A3: 80D, melting point 210°C, brand 59600, Lubrizol, USA.

[0064] Polyamide B (PA):

[0065] B1: PA12, melting point 172°C, brand 7246, DuPont, USA.

[0066] B2: PA12, melting point 178°C, brand 7246, DuPont, USA.

[0067] B3: PA12, melting point 193°C, brand 7246, DuPont, USA.

[0068] Nucleating agent:

[0069] Calcium carbonate, with an average particle size of 1 μm, is commercially available.

[0070] Carbon black, with an average particle size of 3 μm, is commercially available.

[0071] Nano-TiO2, with an average particle size of 1 μm, is commercially available.

[0072] Nano-silicon dioxide, with an average particle size of 200 nm, is commercially available.

[0073] Chain Extender:

[0074] Epoxy chain extender, commercially available.

[0075] Antioxidants:

[0076] Hindered phenolic antioxidant, commercially available.

[0077] softener:

[0078] Silicone softener, commercially available.

[0079] Antistatic Agent:

[0080] Hydrophobic antistatic agent, commercially available.

[0081] Examples 1-6 and Comparative Examples 1-3

[0082] The components and weight proportions of the ultrafine polymer porous fibers of Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Table 1.

[0083] The method for preparing the ultrafine polymer porous fibers of Examples 1 to 6 and Comparative Examples 1 to 3 comprises the following steps:

[0084] S1. All components are premixed according to the weight parts shown in Table 1, added into a twin-screw extruder, melt-extruded, dried, and rolled to obtain a polymer filament; wherein all components are dried by hot air after premixing, and the moisture content after drying is less than 0.05%, and the diameter of the rolled filament is 1.20-2.30 mm;

[0085] S2, placing the polymer filament obtained in step S1 into a high-pressure device to be impregnated with a supercritical fluid (CO2 fluid), after the impregnation is completed, the impregnated polymer filament is loaded onto the unwinding wheel of a micro-extrusion foaming device, and the micro-extrusion device is rapidly heated and foamed, the channel is shaped, and the #1 traction roller is stretched at a constant speed to obtain a polymer foam fiber; wherein the hardness of the polymer filament after impregnation is not less than Shore 40D, and the solubility of the supercritical fluid, the wire feeding speed, the temperature and time of heating and foaming, and the density and diameter of the obtained polymer foam fiber are shown in Table 1;

[0086] S3, heating the polymer foamed fiber obtained in step S2 in the #2 hot channel, performing the first heat stretching, then preheating through the #2 drafting roller, heating in the #3 hot channel, and performing the second heat stretching to obtain the ultrafine polymer porous fiber. The temperature of the #2 hot channel, the linear speed and temperature of the #2 drafting roller, the temperature of the #3 hot channel, and the linear speed and temperature of the #3 drafting roller are shown in Table 1.

[0087] The properties of the ultrafine polymer porous fibers prepared in the examples and comparative examples were tested, and the test results are shown in Table 1.

[0088] Table 1 Component dosage in the examples and comparative examples (parts by weight)

[0089]

[0090]

[0091]

[0092]

[0093] Compared with Example 3, the heating temperature in the stretching process after step S3 in Comparative Example 1 is lower. As can be seen from Table 1, the diameter of the ultrafine polymer porous fiber finally obtained in Comparative Example 1 is 0.23 mm and the density is 0.4 g / cm 3 The bubbles are broken, unevenly distributed, and the fiber appearance is uneven.

[0094] Compared with Example 3, no chain extender was added to the formula of Comparative Example 2. The diameter of the polymer porous fiber prepared in Comparative Example 2 was 0.27 mm and the density was 0.5 g / cm 3 Due to the lack of chain extender in the formula, the fiber viscosity is low during the heating process, the fiber is difficult to stretch, and the foam structure is prone to rupture.

[0095] Compared with Example 3, no softener was added to the formula of Comparative Example 3. The polymer porous fiber finally prepared in this comparative example is relatively hard and not resistant to bending, and is prone to increased friction with the machine during the subsequent weaving process, which increases the difficulty of weaving and affects the wearing comfort.

[0096] Comparative Example 4

[0097] The difference between this comparative example and Example 3 is that in step S2, an extrusion port with a diameter of 0.2 mm is directly selected to prepare ultrafine foamed fibers in one step without going through the post-stretching process of step S3. The rest is the same as Example 3. Since the diameter of the extrusion port is too small to extrude continuous fibers, the preparation of foamed fibers cannot be achieved.

[0098] Comparative Example 5

[0099] The difference between this comparative example and Example 3 is that in the stretching process after step S3, the cold stretching temperature (#2 stretching roller) is 20°C, the hot stretching temperature (#3 stretching roller) is 120°C, and the rest is the same as Example 3 to obtain the polymer porous fiber of this comparative example. The polymer porous fiber of this comparative example has a diameter of 0.31 mm and a density of 0.89 g / cm 3, the thermal conductivity is 0.089W / (m·K). Due to the low temperature of the #2 drawing roller during the pre-drawing process, the fiber quickly cooled down and crystallized after being heated in the #2 hot tunnel, and could not be drawn. In addition, the high temperature of the hot drawing would cause the fiber to melt and defoam, making it difficult to form and sacrificing the pore structure.

[0100] Comparative Example 6

[0101] The difference between this comparative example and Example 3 is that step S3 is not included, the temperature of the channel shaping in step S2 is 300°C, and the rest is the same as Example 3; that is, the temperature of the channel shaping in step S2 is increased, and the post-stretching process of step S3 is not performed to obtain the polymer porous fiber of this comparative example. The polymer porous fiber of this comparative example has a diameter of 0.12 mm and a density of 0.98 g / cm 3 , the thermal conductivity is 0.094W / (m·K). Due to the high temperature in the tunnel, the fiber melts and defoams, sacrificing the cell structure and affecting the uniformity of the fiber strands, which in turn leads to low fiber strength, severe breakage during the stretching process, and difficulty in achieving continuous stretching.

[0102] From the data in Table 1, it can be seen that the diameter of the ultrafine polymer porous fiber prepared in the embodiment of the present invention is between 0.05 mm and 0.21 mm and can be uniformly controlled, and the density can be maintained at 0.20 g / cm 3 -1g / cm 3 The pore size is uniform, the pore distribution is dense, and long-term continuous preparation can be achieved.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An ultrafine polymer porous fiber, characterized in that: The ultrafine polymer porous fiber has a diameter of 0.05 mm to 0.21 mm and a density of 0.20 g / cm 3 -1.00g / cm 3 ; The pores inside the ultrafine polymer porous fiber are spindle-shaped, the size distribution range of the transverse section of the pores is 0.5μm-20μm, and the size distribution range of the radial section is 5μm-80μm; the ultrafine polymer porous fiber comprises the following components by weight: 80-100 parts of polymer, 1-15 parts of nucleating agent, 0.1-1 parts of chain extender, 0-0.5 parts of antioxidant, 0.1-0.2 parts of softener, and 0-2 parts of antistatic agent; the melting point of the polymer is 140℃-250℃; the preparation method of the ultrafine polymer porous fiber comprises the following steps: S1, premixing all components, melt extruding, drying, winding, and impregnating supercritical fluid to obtain polymer filaments; S2, heating and foaming the polymer filament obtained in step S1, shaping it in a channel, and stretching it at a constant speed to obtain polymer foamed fibers; S3, heating and stretching the polymer foamed fiber obtained in step S2, heating again, and stretching again to obtain the ultrafine polymer porous fiber; In step S3, the heating temperature is 20°C-80°C, the stretching temperature is 30°C-150°C, and the line speed is 3m / min-50m / min; the reheating temperature is 80°C-150°C, the re-stretching temperature is 10°C-100°C, and the line speed is 3m / min-250m / min.

2. The ultrafine polymer porous fiber according to claim 1, characterized in that: The hardness of the polymer is 40D-85D.

3. The ultrafine polymer porous fiber according to claim 1, characterized in that: At least one of the following (1)-(6): (1) The polymer comprises at least one of a thermoplastic elastomer, a polyester, and a polyamide; (2) The nucleating agent includes at least one of calcium carbonate, carbon black, nano-TiO2, montmorillonite, nano-silicon dioxide, carbon nanotubes, and PTFE powder; (3) the chain extender comprises at least one of a difunctional acid derivative, an isocyanate, an anhydride and an epoxide; (4) The antioxidant includes at least one of an amine antioxidant and a phosphorus antioxidant; (5) The softener includes at least one of a silicone softener, a cationic softener, a nonionic softener, and a composite softener; (6) The antistatic agent includes a hydrophobic antistatic auxiliary agent.

4. A processing device for ultrafine polymer porous fibers according to any one of claims 1 to 3, characterized in that: Including in order: Wire feeding unit, heat insulation unit, micro extrusion heating unit, micro extrusion die, and three sets of heating and drawing units.

5. The ultrafine polymer porous fiber according to claim 1, characterized in that: At least one of the following (1)-(5): (1) In the step S1, the melt extrusion is carried out using a twin-screw extruder, and the temperature of the melt extrusion is 250° C.-320° C.; (2) In step S1, the supercritical fluid is CO2 fluid, N2 fluid, or a mixed fluid of CO2 fluid and N2 fluid; (3) In step S1, the solubility of the supercritical fluid in the polymer filament is 0.5wt%-7.0wt%; (4) In the step S1, all the components are dried by hot air after being premixed, and the moisture content of the materials after drying is less than 0.05%.

6. The ultrafine polymer porous fiber according to claim 1, characterized in that: At least one of the following (1)-(4): (1) In the step S2, the wire feeding speed when heating and foaming the polymer wire obtained in the step S1 is 50 mm / s-100 mm / s; (2) In step S2, the heating and foaming temperature is 200°C-380°C, and the residence time is 0.3s-3.0s; (3) In step S2, the temperature of the tunnel shaping is 140°C-270°C, and the residence time in the tunnel is 0.1s-2.0s; (4) In step S2, the speed of the constant speed drafting is 1m / min-8m / min; (5) In step S2, the diameter of the polymer foam fiber is 0.1 mm-0.5 mm.

7. Application of the ultrafine polymer porous fiber according to any one of claims 1 to 6 in the fields of outdoor sportswear, functional clothing, and electronic wearable devices.

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