A superfine fiber porous material based on electrostatic air-jet spinning and its preparation method

Abstract

This invention relates to an ultrafine fiber porous material based on electrostatic air-jet spinning and its preparation method, belonging to the technical field of ultrafine fiber materials. The method includes: firstly, a prepared spinning solution is transported to a frequency converter for storage; then, the spinning solution is injected into an electrostatic air-jet spinning device. Under the dual action of an electric field and an airflow field, the jet is stretched, refined, and whipped into coils. Rapid phase separation occurs through moisture-induced jet flow, fixing the fiber's coil morphology to obtain a fiber aggregate material, which can be a fiber membrane or fiber flakes. Finally, the fiber aggregate material is fused together / hot-rolled with adhesive, and dried and shaped to obtain the ultrafine fiber porous material. Compared with existing technologies, this invention achieves efficient preparation of ultrafine fiber porous materials based on electrostatic air-jet spinning. Furthermore, the method of this invention allows for precise control of the porosity of the ultrafine fiber porous material.

Description

Technical Field

[0001] This invention relates to the field of ultrafine fiber materials technology, specifically to an ultrafine fiber porous material based on electrostatic air-jet spinning and its preparation method. Background Technology

[0002] Ultrafine fibers possess advantages such as small diameter and high specific surface area, giving materials made from them many superior properties compared to conventional fiber materials, such as high porosity, lightweight and softness. They hold immense application potential in fields such as high-temperature insulation, cold-proofing, and filtration. The main methods for preparing ultrafine fibers include melt-blown spinning, centrifugal spinning, and air-jet spinning. Among these, melt-blown spinning produces fibers with diameters mostly between 2 and 10 μm, and further refinement is difficult, limiting the widespread application of this method. Centrifugal spinning, with its high-speed rotation, can cause fiber breakage, resulting in poor product continuity. Air-jet spinning, on the other hand, struggles to control the airflow during fiber preparation, leading to significant variations in fiber diameter and morphology, thus affecting product quality.

[0003] Electrostatic air-jet spinning technology adds an air-jet device to electrostatic spinning, enabling the jet to be rapidly drawn under the combined action of electrostatic and airflow forces to achieve efficient preparation of ultrafine fibers. High-voltage electrostatics not only draw and refine the jet but also stabilize its state, while the high-speed airflow further increases the fiber production rate. However, currently, even with the addition of the air-jet device, only fiber membranes can be produced; it is impossible to produce fluffy fiber sheets in one step. Fiber sheets can only be formed through multiple stacking and web-laying processes in subsequent steps, making the process complex.

[0004] To address the aforementioned issues, researchers have conducted relevant studies in this field. Patent ZL201811009580.5 uses an airflow nozzle at the center of the nozzle and multiple spinning nozzles at the edge, simultaneously stretching the jets ejected from multiple spinning nozzles using central airflow. This easily leads to fiber tufting, affecting product quality. Patent ZL201210037687.7 places the spinneret orifice coaxially inside the air pore, using airflow to enhance the jet stretching effect to prepare polysulfonamide nanofiber webs. This method can only enhance the jet stretching effect through airflow, forming only dense fiber web materials, but cannot control the fiber forming structure or the morphology of the fiber aggregate material. Patent ZL202210470343.9 uses electrospinning to prepare nanofibers while simultaneously using flash spinning to prepare microfibers, utilizing opposing reverse airflows to cause the fibers to entangle, curl, and interpenetrate. This method involves simultaneous filament output from two spinnerets, which can easily lead to mutual interference between the devices. Furthermore, the fiber curling shape is difficult to fix, making it impossible to adjust the final material morphology. Patent ZL201410667969.4 discloses a method and apparatus for producing polymer nanofibers using high-speed airflow and high-voltage electrostatics. This method utilizes a double-layer high-speed airflow and high-voltage electrostatics to rapidly transport and draw the polymer solution, thereby increasing the electrospinning rate and enabling the rapid preparation of polymer nanofibers. However, this apparatus uses the siphon effect generated by the pressure difference between the double-layer high-speed airflows to transport the polymer spinning solution. The interference between the double-layer high-speed airflows in different spinning nozzles is difficult to eliminate, and the prepared fiber material has a poor morphology and a limited variety of styles, making it difficult to meet product requirements. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one of the defects in the prior art and provide an ultrafine fiber porous material based on electrostatic air-jet spinning and its preparation method. This invention achieves efficient preparation of ultrafine fiber porous materials based on electrostatic air-jet spinning. Furthermore, the method of this invention allows for precise control of the porosity of the ultrafine fiber porous material, specifically in the following ways:

[0006] While existing technologies can produce ultrafine fibers, their production efficiency is difficult to improve, greatly limiting actual production needs. This invention, by utilizing high-voltage electrostatic drawing of the spinning solution and incorporating a high-speed vortex airflow, can rapidly drive the spinning solution spray, significantly increasing production speed.

[0007] While existing technologies can prepare ultrafine fiber porous materials, the material morphology is limited, typically existing only in the form of membranes. This invention proposes a moisture-induced jet phase separation method. By controlling the phase separation and solidification speed of the charged jet, combined with a high-speed vortex airflow, precise control over the different crimp rates and entanglement degrees of ultrafine fibers can be achieved, resulting in dense fiber membranes or fluffy fiber flakes. This effectively broadens the application of ultrafine fiber porous materials in fields such as heat insulation, filtration, thermal insulation, and sound absorption.

[0008] Existing microfiber porous materials suffer from easy delamination between layers and poor mechanical properties, limiting their practical applications. This invention designs a fusion bonding / spray adhesive hot rolling and drying setting process, which enhances the physical connection between fibers, making the microfiber porous material less prone to delamination and possessing good compressive resilience and tensile breaking strength.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] One objective of this invention is to provide a method for preparing ultrafine fiber porous materials based on electrostatic air-jet spinning, comprising the following steps:

[0011] S1. Prepare the spinning solution; adjust the stirring speed according to the solution viscosity before each addition of raw materials to ensure rapid dissolution and reaction of raw materials; at the same time, set up a frequency conversion temperature control device to adjust the solution viscosity and dispersion state by real-time control of the temperature of the reaction system to ensure long-term stable storage of the spinning solution.

[0012] S2. A flow-blocking bar is installed across the air outlet at the coaxial nozzle, and a receiving plate is installed directly opposite the discharge port of the coaxial nozzle. The spinning solution is extruded through the coaxial nozzle and forms a jet under the action of high voltage electrostatics. At the same time, the airflow passes through the flow-blocking bar to form a vortex airflow, which drives the charged jet to perform high-speed stretching and whipping curling. The size of the vortex can be changed by adjusting the airflow speed, thereby controlling the curling amplitude and shape of the jet.

[0013] S3. Set up a constant temperature and humidity control device to control the phase separation and solidification speed of the jet by adjusting the moisture concentration in the spinning area, fix the different shapes of the jet, and thus change the shape and degree of entanglement of the fiber; when the jet separates slowly, straight fibers are obtained to form a fiber membrane; when the jet separates rapidly, crimped fibers are obtained. The crimped fibers are intertwined to form a three-dimensional interlocking structure to form fiber flocs.

[0014] S4. When the product obtained in S3 is a fiber membrane, the fiber membrane is placed at a high temperature to fuse and composite the fibers, and then dried and shaped to obtain an ultrafine fiber porous membrane, which is an ultrafine fiber porous material; or, when the product obtained in S3 is a fiber floc, the fiber floc is sprayed with adhesive and hot rolled, and then dried and shaped to obtain an ultrafine fiber floc material, which is an ultrafine fiber porous material.

[0015] More specifically, the phase separation state of the jet can be confirmed by turbidity point titration of the spinning solution under different humidity levels. At high humidity concentrations (>80%), obvious phase separation occurs within 30 seconds, indicating a rapid phase separation rate. At low humidity concentrations (<50%), phase separation occurs after more than 130 seconds, indicating a slow phase separation rate. Because the fiber formation rate is very fast and the jet surface area is large during electrospinning, solutions with rapid phase separation will undergo phase separation within milliseconds after ejection.

[0016] More specifically, the present invention includes a constant temperature and humidity control device, which comprises a moisture delivery pipe, a moisture outlet, a temperature and humidity sensor, an air pump, and a temperature and humidity control / feedback adjustment system. The temperature and humidity control / feedback adjustment system sets the required spinning temperature and humidity. Moisture is pressurized by the air pump and delivered through the moisture delivery pipe to the moisture outlet for uniform dispersion in the spinning area. During the spinning process, the temperature and humidity sensor monitors the temperature and humidity changes in the area in real time and feeds back to the temperature and humidity control / feedback adjustment system to maintain a constant temperature and humidity in the area. By adjusting the moisture concentration in the spinning area, the phase separation and solidification rate of the jet is controlled, and different jet morphologies are fixed, thereby changing the fiber morphology and entanglement degree.

[0017] Furthermore, the spinning solution of the ultrafine fiber porous material includes raw materials and a solvent for dissolving the raw materials, wherein the concentration of the raw materials is 10-60 wt%.

[0018] The raw materials are selected from one or more of the following: polyethylene oxide, polyvinyl chloride, polyvinylidene fluoride, polycarbonate, polymethyl methacrylate, polypropylene terephthalate, polystyrene, polyurethane, polybenzimidazole, polyethylene terephthalate, polycaprolactone, polyethylene, polylactic acid, polyhydroxybutyrate, polyacrylonitrile, polyamide, polyamide-imide, polyvinyl alcohol, polyvinyl butyral, polysulfone, polyethyleneimine, polyimide, aramid 1313, titanium tetramethylethanol, titanium tetraethanolamine, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, titanium isobutoxide, ethyl orthosilicate, titanium tert-butoxide, titanium tetrapentoxide, titanium isooctanol, zirconium tetramethylethanol, zirconium tetraethanolamine, zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, zirconium isobutoxide, zirconium tert-butoxide, zirconium tetrapentoxide, aluminum trimethoxy, aluminum triethanolamine, aluminum tri-n-propoxy, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, or aluminum tert-butoxide.

[0019] The solvent is selected from one or more of water, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol, formic acid, acetic acid, dimethyl sulfoxide, toluene, acetone, cyclohexane, isobutanol, dichloromethane, butyl acetate, ethyl acetate, chloroform, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, ethylene glycol, butanediol, hexanediol, glycerol, carbon tetrachloride, benzene, toluene, dichloroethane, dichloromethane, chloroform, diethyl ether, diphenyl ether, ethyl acetate, acetone, tetrahydrofuran, N-methylpyrrolidone, or N,N-dimethylformamide.

[0020] Further, the raw material is selected from one or more of polyurethane, titanium n-butoxide, polysulfone, or tetraethyl orthosilicate; the solvent is selected from one or more of N,N-dimethylformamide, water, or ethanol. Further, in S2, the spinning solution forms a jet under electrostatic action of 0–150 kV; the airflow velocity is 0–25 m / s; the receiving distance between the coaxial nozzle and the receiving plate is 10–70 cm; and the injection rate at the coaxial nozzle outlet is 5–80 ml / h.

[0021] Furthermore, in S3, the spinning temperature in the spinning area is 10–50°C, the relative humidity is 10–99%, and the fiber crimp rate is 5–60%.

[0022] Furthermore, in S4, the welding method of the fusion composite is one or more of the following: thermal welding, ultrasonic welding, microwave irradiation welding, infrared irradiation welding, ultraviolet irradiation welding, electron beam irradiation welding, and plasma irradiation welding, with the heating roller temperature being 20 to 800°C and the microwave generator frequency being 3000 to 300000MHz.

[0023] Furthermore, in S4, during the hot rolling process of adhesive spraying, the adhesive spraying volume of the atomizing nozzle used is in the range of 0 to 50 mL / min, and the diameter of the atomized adhesive is 1 to 10 μm.

[0024] Furthermore, in S4, during the drying and shaping process, hot air and cold air are used to post-treat the ultrafine fiber porous material. The temperature range of the hot air is 40 to 150°C, the temperature range of the cold air is 5 to 20°C, and the suction pressure is 0.1 to 10 MPa.

[0025] The second objective of this invention is to provide an ultrafine fiber porous material based on electrostatic air-jet spinning, which is prepared by the method described above.

[0026] Furthermore, the ultrafine fiber porous material is an ultrafine fiber porous membrane or an ultrafine fiber flocculent material;

[0027] When the ultrafine fiber porous material is an ultrafine fiber porous membrane:

[0028] In this invention, the thickness of the ultrafine fiber porous membrane is 0.1–2 mm;

[0029] In this invention, the porosity of the ultrafine fiber porous membrane is 20-90%;

[0030] In this invention, the tensile strength of the ultrafine fiber porous membrane is higher than 5 MPa;

[0031] In this invention, the diameter of the ultrafine fiber porous membrane is 50–10000 nm;

[0032] When the ultrafine fiber porous material is an ultrafine fiber flocculent material:

[0033] In this invention, the thickness of the ultrafine fiber flocculation material is 5-60 mm;

[0034] In this invention, the bulk density of the ultrafine fiber flocculation material is 2–100 mg / cm³. 3 ;

[0035] In this invention, the porosity of the ultrafine fiber flocculent material is higher than 95%;

[0036] In this invention, the compression resilience of the ultrafine fiber wadding material is above 90%;

[0037] In this invention, the elongation at break of the ultrafine fiber wadding material is higher than 10%;

[0038] In this invention, the diameter of the ultrafine fiber flocculent material is 50–10000 nm.

[0039] The technical principle of this invention is as follows:

[0040] The porosity-adjustable ultrafine fiber porous material of the present invention is prepared by a method of preparing spinning raw materials through spinning solution preparation, electrostatic air-jet spinning, jet phase separation and solidification into fibers, and fusion bonding / spraying adhesive hot rolling-drying and shaping.

[0041] Long-term stable storage of spinning solution: First, the dissolved spinning solution is transported to a sealed tank. The temperature of the system is adjusted in real time to regulate the viscosity and dispersion state of the spinning solution, thereby inhibiting the gelation behavior of the spinning solution and obtaining a spinning solution that can be stored stably for a long time.

[0042] Phase separation molding of ultrafine fibers: The spinning solution is extruded through a nozzle and forms a jet under the combined action of high-voltage electrostatics and high-speed airflow. Simultaneously, the airflow passes through a vortex formed by a baffle bar, driving the jet to undergo high-speed stretching and whipping curling, thus forming jets with different morphologies (straight or curled). A constant temperature and humidity control device is installed to control the phase separation and solidification rate of the jet by adjusting the moisture concentration. In conjunction with adjusting the vortex size, when the jet undergoes rapid phase separation and solidification, the curled shape of the jet can be quickly fixed, resulting in curled fibers and forming high-porosity ultrafine fiber flocs. When the jet undergoes slow phase separation, the solidification rate decreases, resulting in straight fibers and forming low-porosity ultrafine fiber membrane materials. Therefore, moisture-induced phase separation molding technology can change the curling and entanglement structure of fibers, obtaining fiber aggregate materials (fiber flocs or fiber membranes) with different porosities.

[0043] Strengthening and shaping of ultrafine fiber porous materials: Ultrafine fiber membrane materials are fused together, ultrafine fiber floc materials are sprayed with adhesive and hot rolled, and then dried and shaped to finally obtain ultrafine fiber porous materials with adjustable porosity and high strength.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] (1) The coaxial nozzle of this invention is designed with a flow-blocking bar that runs across the air outlet. The prepared spinning solution is placed in the spinning module to quickly form fibers. At the same time, high-speed airflow and phase separation molding technology are used to control the crimping degree and entanglement morphology of the fibers. According to the porosity of the ultrafine fiber material and the application requirements, it is fused and laminated or hot-rolled with adhesive, and finally dried and shaped. This method can obtain ultrafine fiber porous materials with adjustable porosity and good mechanical properties, thus broadening the application scenarios of ultrafine fiber materials.

[0046] (2) This invention can use different kinds of polymers or inorganic spinning solutions for efficient spinning, encompassing organic and inorganic spinning solution systems. The method is highly versatile and has a wide range of applications. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the overall temperature and humidity control device of the present invention;

[0048] The numbers in the diagram indicate: 1-moist steam conveying pipe, 2-moist steam outlet, 3-spinneret, 4-temperature and humidity sensor, 6-air pump, 7-temperature and humidity control / feedback adjustment system. Detailed Implementation

[0049] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0050] Figure 1 The following is a schematic diagram of the overall temperature and humidity control device used in the embodiments. The temperature and humidity control device includes a moisture delivery pipe 1, a moisture outlet 2, a temperature and humidity sensor 4, an air pump 6, and a temperature and humidity control / feedback adjustment system 7. The temperature and humidity control / feedback adjustment system 7 sets the required spinning temperature and humidity. The moisture is pressurized by the air pump 6 and delivered through the moisture delivery pipe 1 to the moisture outlet 2, where it is evenly distributed to the spinning area. During the spinning process, the temperature and humidity sensor 4 monitors the temperature and humidity changes in the area in real time and feeds them back to the temperature and humidity control / feedback adjustment system 7 to maintain a constant temperature and humidity in the area. By adjusting the moisture concentration in the spinning area, the phase separation and solidification rate of the jet is controlled, and different jet morphologies are fixed, thereby changing the fiber morphology and entanglement degree.

[0051] The spinning solution of the ultrafine fiber porous material in this invention includes raw materials and a solvent for dissolving the raw materials, wherein the concentration of the raw materials is 10-60 wt%.

[0052] The raw materials are selected from one or more of the following: polyethylene oxide, polyvinyl chloride, polyvinylidene fluoride, polycarbonate, polymethyl methacrylate, polypropylene terephthalate, polystyrene, polyurethane, polybenzimidazole, polyethylene terephthalate, polycaprolactone, polyethylene, polylactic acid, polyhydroxybutyrate, polyacrylonitrile, polyamide, polyamide-imide, polyvinyl alcohol, polyvinyl butyral, polysulfone, polyethyleneimine, polyimide, aramid 1313, titanium tetramethylethanol, titanium tetraethanolamine, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, titanium isobutoxide, ethyl orthosilicate, titanium tert-butoxide, titanium tetrapentoxide, titanium isooctanol, zirconium tetramethylethanol, zirconium tetraethanolamine, zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, zirconium isobutoxide, zirconium tert-butoxide, zirconium tetrapentoxide, aluminum trimethoxy, aluminum triethanolamine, aluminum tri-n-propoxy, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, or aluminum tert-butoxide.

[0053] The solvent is selected from one or more of water, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol, formic acid, acetic acid, dimethyl sulfoxide, toluene, acetone, cyclohexane, isobutanol, dichloromethane, butyl acetate, ethyl acetate, chloroform, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, ethylene glycol, butanediol, hexanediol, glycerol, carbon tetrachloride, benzene, toluene, dichloroethane, dichloromethane, chloroform, diethyl ether, diphenyl ether, ethyl acetate, acetone, tetrahydrofuran, N-methylpyrrolidone, or N,N-dimethylformamide.

[0054] Example 1

[0055] This embodiment provides a method for preparing ultrafine fiber porous materials based on electrostatic air-jet spinning, the specific steps of which are as follows:

[0056] Step 1: The spinning solution raw materials include 20wt% polyurethane and 80wt% N,N-dimethylformamide. The polyurethane and N,N-dimethylformamide are added to the reactor, and the stirring speed is adjusted according to the solution viscosity before each addition of raw materials. After stirring and dissolving in the reactor, the polyurethane spinning solution is obtained. At the same time, a frequency converter temperature control device is set to adjust the temperature of the spinning solution system to 60℃ to ensure long-term stable storage of the spinning solution.

[0057] Step 2: The polyurethane spinning solution is extruded from the coaxial nozzle at a speed of 15 mL / h and formed into a jet under the action of 60 kV high voltage electrostatics. At the same time, an airflow of 15 m / s is blown out from each jet hole. The distance between the spinneret and the receiving plate is set to 60 cm. The airflow passes through the baffle bar to form a vortex airflow, which drives the jet to perform high-speed stretching and whipping curling.

[0058] Step 3: Set the temperature in the spinning area to 30℃ and the relative humidity to 50%. Under this humidity, perform turbidity point titration on the spinning solution. Phase separation occurs after more than 130 seconds. The phase separation speed is slow, the fiber crimp rate is 5%, and an ultrafine fiber membrane is formed.

[0059] Step 4: The prepared ultrafine fiber membrane is placed under ultrasound to generate high temperature so that the fibers are fused and bonded together. Then it is dried, cooled and shaped to obtain a dense ultrafine fiber porous membrane material.

[0060] The final obtained ultrafine fiber porous material has a fiber diameter of 180 nm, a thickness of 0.2 mm, a porosity of 35%, and a tensile strength of 15 MPa.

[0061] Example 2

[0062] This embodiment provides an ultrafine fiber porous material based on electrostatic air-jet spinning and its preparation method, the specific steps of which are as follows:

[0063] Step 1: The spinning solution raw materials include 10 wt% titanium n-butoxide, 70 wt% water, and 10 wt% ethanol. The titanium n-butoxide solution and ethanol are added to the reactor, and the stirring speed is adjusted according to the solution viscosity before each addition of raw materials. After stirring and dissolving in the reactor, the titanium n-butoxide spinning solution is obtained. At the same time, a frequency converter temperature control device is set to adjust the temperature of the spinning solution system to 50°C to ensure long-term stable storage of the spinning solution.

[0064] Step 2: The titanium butyrate spinning solution is extruded from the coaxial nozzle at a speed of 5 mL / h and formed into a jet under the action of 50 kV high voltage electrostatics. At the same time, an airflow of 10 m / s is blown out from each jet hole. The distance between the spinneret and the receiving plate is set to 45 cm. The airflow passes through the baffle bar to form a vortex airflow, which drives the jet to perform high-speed stretching and whipping curling.

[0065] Step 3: Set the temperature in the spinning area to 25℃ and the relative humidity to 45%. The jet phase separation rate is relatively slow, and the fiber crimp rate is 12%, forming an ultrafine fiber membrane. This is because when using an inorganic spinning solution, water vapor in the spinning environment continuously enters the jet, causing water and alcohol to dissolve each other, reducing solvent evaporation in the jet, which is not conducive to fiber formation. Therefore, the jet phase separation rate is relatively slow.

[0066] Step 4: The prepared ultrafine fiber membrane is placed under ultrasound to generate high temperature so that the fibers are fused and bonded together. Then it is dried, cooled and shaped to obtain a dense ultrafine fiber porous membrane material.

[0067] The final obtained ultrafine fiber porous material has a fiber diameter of 500 nm, a thickness of 0.5 mm, a porosity of 50%, and a tensile strength of 7 MPa.

[0068] Example 3

[0069] This embodiment provides an ultrafine fiber porous material based on electrostatic air-jet spinning and its preparation method, the specific steps of which are as follows:

[0070] Step 1: The spinning solution raw materials include 20wt% polysulfone, 10% polyurethane, and 70wt% N,N-dimethylformamide. Polysulfone, polyurethane, and N,N-dimethylformamide are added to the reactor, and the stirring speed is adjusted according to the solution viscosity before each addition of raw materials. After stirring and dissolving in the reactor, a polyurethane spinning solution is obtained. At the same time, a frequency converter temperature control device is set to adjust the temperature of the spinning solution system to 80℃ to ensure long-term stable storage of the spinning solution.

[0071] Step 2: The polyurethane spinning solution is extruded from the coaxial nozzle at a speed of 30 mL / h and formed into a jet under the action of 80 kV high voltage electrostatics. At the same time, an airflow of 20 m / s is blown out from each jet hole. The distance between the spinneret and the receiving plate is set to 70 cm. The airflow passes through the baffle bar to form a vortex airflow, which drives the jet to perform high-speed stretching and whipping curling.

[0072] Step 3: Set the temperature in the spinning area to 30℃ and the relative humidity to 90%. Under this humidity, perform turbidity point titration on the spinning solution. Phase separation will occur within 20 seconds. The phase separation speed is fast, the fiber crimp rate is 39%, and ultrafine fiber flocs are formed.

[0073] Step 4: The surface of the prepared microfiber is sprayed with adhesive and then hot rolled by a high-temperature roller, followed by drying, cooling and shaping to finally obtain a fluffy microfiber porous material.

[0074] The final obtained ultrafine fiber porous material has a fiber diameter of 3500 nm, a thickness of 40 mm, a porosity of 98%, and a bulk density of 3 mg / cm³. 3 The compression recovery rate is 98%, and the elongation at break is 34%.

[0075] Example 4

[0076] This embodiment provides an ultrafine fiber porous material based on electrostatic air-jet spinning and its preparation method, the specific steps of which are as follows:

[0077] Step 1: The spinning solution raw materials include 10 wt% tetraethyl orthosilicate, 70 wt% water, and 10 wt% ethanol. Tetraethyl orthosilicate, water, and ethanol are added to the reaction vessel, and the stirring speed is adjusted according to the solution viscosity before each addition of raw materials. After stirring and dissolving in the reaction vessel, tetraethyl orthosilicate spinning solution is obtained. At the same time, a frequency converter temperature control device is set to adjust the temperature of the spinning solution system to 60°C to ensure long-term stable storage of the spinning solution.

[0078] Step 2: The tetraethyl orthosilicate spinning solution is extruded from the coaxial nozzle at a speed of 35 mL / h and formed into a jet under the action of 90 kV high voltage electrostatics. At the same time, an airflow of 25 m / s is blown out from each jet hole. The distance between the spinneret and the receiving plate is set to 85 cm. The airflow passes through the baffle bar to form a vortex airflow, which drives the jet to perform high-speed stretching and whipping curling.

[0079] Step 3: Set the temperature in the spinning zone to 25℃ and the relative humidity to 25%. At this temperature, the jet phase separation rate is relatively fast, and the fiber crimp rate is 43%, forming ultrafine fiber flocs. This is because when using an inorganic spinning solution, the less moisture in the spinning environment, the faster the water and alcohol in the solvent will evaporate, which is beneficial for fiber formation, hence the faster jet phase separation rate.

[0080] Step 4: The surface of the prepared microfiber is sprayed with adhesive and then hot rolled by a high-temperature roller, followed by drying, cooling and shaping to finally obtain a fluffy microfiber porous material.

[0081] The final obtained ultrafine fiber porous material has a fiber diameter of 375 nm, a thickness of 60 mm, a porosity of 99%, and a bulk density of 4.5 mg / cm³. 3 The compression recovery rate is 95%, and the elongation at break is 22%.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing ultrafine fiber porous materials based on electrostatic air-jet spinning, characterized in that, Includes the following steps: S1. Prepare the spinning solution; S2. A flow-blocking bar is installed across the air outlet at the coaxial nozzle, and a receiving plate is installed directly opposite the discharge port of the coaxial nozzle. The spinning solution is extruded through the coaxial nozzle and forms a jet under the action of high voltage electrostatics. At the same time, the airflow passes through the flow-blocking bar to form a vortex airflow, which drives the charged jet to perform high-speed stretching and whipping curling. The size of the vortex can be changed by adjusting the airflow speed, thereby controlling the curling amplitude and shape of the jet. S3. Set up a constant temperature and humidity control device to control the phase separation and solidification speed of the jet by adjusting the moisture concentration in the spinning area, fix the different shapes of the jet, and thus change the shape and degree of entanglement of the fiber; when the jet separates slowly, straight fibers are obtained to form a fiber membrane; when the jet separates rapidly, crimped fibers are obtained. The crimped fibers are intertwined to form a three-dimensional interlocking structure to form fiber flocs. S4. When the product obtained in S3 is a fiber membrane, the fiber membrane is placed at a high temperature to fuse and composite the fibers, and then dried and shaped to obtain an ultrafine fiber porous membrane, which is an ultrafine fiber porous material; or, when the product obtained in S3 is a fiber floc, the fiber floc is sprayed with adhesive and hot rolled, and then dried and shaped to obtain an ultrafine fiber floc material, which is an ultrafine fiber porous material.

2. The method for preparing ultrafine fiber porous materials based on electrostatic air-jet spinning according to claim 1, characterized in that, The spinning solution of the ultrafine fiber porous material includes raw materials and a solvent for dissolving the raw materials, wherein the concentration of the raw materials is 10-60 wt%. The raw materials are selected from one or more of the following: polyethylene oxide, polyvinyl chloride, polyvinylidene fluoride, polycarbonate, polymethyl methacrylate, polypropylene terephthalate, polystyrene, polyurethane, polybenzimidazole, polyethylene terephthalate, polycaprolactone, polyethylene, polylactic acid, polyhydroxybutyrate, polyacrylonitrile, polyamide, polyamide-imide, polyvinyl alcohol, polyvinyl butyral, polysulfone, polyethyleneimine, polyimide, aramid 1313, titanium tetramethylethanol, titanium tetraethanolamine, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, titanium isobutoxide, ethyl orthosilicate, titanium tert-butoxide, titanium tetrapentoxide, titanium isooctanol, zirconium tetramethylethanol, zirconium tetraethanolamine, zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, zirconium isobutoxide, zirconium tert-butoxide, zirconium tetrapentoxide, aluminum trimethoxy, aluminum triethanolamine, aluminum tri-n-propoxy, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, or aluminum tert-butoxide. The solvent is selected from one or more of water, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol, formic acid, acetic acid, dimethyl sulfoxide, toluene, acetone, cyclohexane, isobutanol, dichloromethane, butyl acetate, ethyl acetate, chloroform, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, ethylene glycol, butanediol, hexanediol, glycerol, carbon tetrachloride, benzene, toluene, dichloroethane, dichloromethane, chloroform, diethyl ether, diphenyl ether, ethyl acetate, acetone, tetrahydrofuran, N-methylpyrrolidone, or N,N-dimethylformamide.

3. The method for preparing ultrafine fiber porous materials based on electrostatic air-jet spinning according to claim 2, characterized in that, The raw material is selected from one or more of polyurethane, titanium n-butoxide, polysulfone, or tetraethyl orthosilicate; the solvent is selected from one or more of N,N-dimethylformamide, water, or ethanol.

4. In the method for preparing ultrafine fiber porous material based on electrostatic air jet spinning according to claim 1, in S2, the spinning solution forms a jet under the electrostatic action of 0-150kV; the velocity of the airflow is 0-25m / s; the receiving distance between the coaxial nozzle and the receiving plate is 10-70cm; and the injection rate of the coaxial nozzle outlet is 5-80ml / h.

5. In the method for preparing ultrafine fiber porous material based on electrostatic air-jet spinning according to claim 1, in S3, the spinning temperature in the spinning area is 10-50℃, the relative humidity is 10-99%, and the fiber crimp rate is 5-60%.

6. In the method for preparing ultrafine fiber porous material based on electrostatic air-jet spinning according to claim 1, in S4, the welding method of the fusion composite is one or more of the following: thermal welding, ultrasonic welding, microwave irradiation welding, infrared irradiation welding, ultraviolet irradiation welding, electron beam irradiation welding, and plasma irradiation welding.

7. In the method for preparing ultrafine fiber porous material based on electrostatic air-jet spinning according to claim 1, in S4, during the hot rolling process of adhesive spraying, the amount of adhesive sprayed by the atomizing nozzle is in the range of 0-50 mL / min, and the diameter of the atomized adhesive is 1-10 μm.

8. In the preparation method of ultrafine fiber porous material based on electrostatic air-jet spinning according to claim 1, in S4, during the drying and setting process, hot air and cold air are used to post-treat the ultrafine fiber porous material, the temperature range of the hot air is 40-150℃, the temperature range of the cold air is 5-20℃, and the suction pressure is 0.1-10MPa.

9. A porous material of ultrafine fibers based on electrostatic air-jet spinning, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The ultrafine fiber porous material based on electrostatic air-jet spinning according to claim 9, characterized in that, The ultrafine fiber porous material is an ultrafine fiber porous membrane or an ultrafine fiber flocculent material. When the ultrafine fiber porous material is an ultrafine fiber porous membrane, at least one of the following conditions is met: ① The thickness of the ultrafine fiber porous membrane is 0.1–2 mm; ②The porosity of the ultrafine fiber porous membrane is 20-90%; ③ The tensile strength of the ultrafine fiber porous membrane is higher than 5 MPa; ④ The diameter of the ultrafine fiber porous membrane is 50–10000 nm; When the ultrafine fiber porous material is an ultrafine fiber flocculent material, at least one of the following conditions must be met: ①The thickness of the ultrafine fiber flocculent material is 5-60 mm; ② The bulk density of the ultrafine fiber flocculent material is 2-100 mg / cm³. 3 ; ③ The porosity of the ultrafine fiber flocculent material is higher than 95%; ④ The compression resilience of the ultrafine fiber wadding material is above 90%; ⑤ The elongation at break of the ultrafine fiber wadding material is higher than 10%; ⑥ The diameter of the ultrafine fiber flocculent material is 50-10000 nm.

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