A one-way moisture guiding micro / nanofiber membrane and a centrifugal spinning method for preparing the same

Abstract

The present application belongs to the technical field of functional micro / nanofiber preparation, and particularly relates to a unidirectional moisture-conducting micro / nanofiber membrane and a centrifugal spinning preparation method thereof. The present application mixes a polymer and a solvent for centrifugal spinning, and obtains a porous fiber membrane product by using solvent rapid evaporation to form pores. In the spinning process, a high-power light source is irradiated, and the light source is directly irradiated on the spinneret and the spun fiber. In the irradiation process, the temperature of the spinning environment is rapidly increased, and the volatilization of the solvent on the fiber after the fiber is formed is accelerated, which is beneficial to the construction of the porous structure of the fiber. The SBS porous membrane contains hydroxyl radicals through low-temperature cold plasma modification, and the SBS porous membrane and acrylamide occur radical graft polymerization under the protection of nitrogen, so that the SBS porous membrane is endowed with superhydrophilicity. Then, a unidirectional moisture-conducting fiber membrane is prepared by using a hot-pressing composite method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional micro / nanofiber preparation, and particularly relates to a unidirectional moisture-conducting micro / nanofiber membrane and a centrifugal spinning preparation method thereof. BACKGROUND

[0002] Traditional unidirectional moisture-conducting garments on the current market mainly use cotton and polyester as raw materials. These materials are favored due to their softness and good moisture absorption. However, these traditional fabrics have obvious deficiencies in water evaporation rate, resulting in reduced comfort for wearers in high humidity environments. In addition, the preparation process of these fabrics is relatively complex, and a large amount of hydrophilic / hydrophobic finishing agent is required in the hydrophobic modification process, which not only increases production costs, but also may have adverse effects on the environment and human health.

[0003] To solve the above problems, new functional fiber membranes prepared based on centrifugal spinning technology are gradually becoming a new choice in the industry. SBS (styrene-butadiene-styrene block copolymer) is a thermoplastic elastomer with excellent performance, and is favored for its perfect combination of high elasticity, strength and thermoplasticity. SBS fiber membrane effectively increases the water evaporation rate and improves the wearing comfort by plasma gas-liquid induced grafting of hydrophilic monomers and then hot pressing composite original membrane. This preparation method not only simplifies the process flow, but also reduces the potential risks to the environment and human health.

[0004] The good elasticity of SBS fiber membrane makes it more suitable for sports clothing, providing a better sports experience for wearers. Compared with traditional fabrics, these improvements of SBS fiber membrane make it have broad application prospects in the field of functional clothing. With the improvement of environmental protection and health awareness, SBS fiber membrane is expected to become an effective substitute for traditional unidirectional moisture-conducting fabrics due to its potential in reducing environmental pollution and improving wearing comfort. SUMMARY

[0005] The purpose of the present application is to provide a unidirectional moisture-conducting micro / nanofiber membrane, which is constructed by centrifugal spinning and hydrophilic modification to solve the technical defect that the water absorbed by the fiber of traditional unidirectional moisture-conducting clothing is difficult to discharge in a humid and hot environment.

[0006] The technical solution adopted by the present application to solve its technical problems is:

[0007] A centrifugal spinning preparation method of a unidirectional moisture-conducting micro / nanofiber membrane, the method comprising the following steps:

[0008] (1) Centrifugal spinning: mix the polymer with the solvent to obtain a spinning solution, and the mass concentration of the polymer is 20wt%-24wt%;

[0009] The polymer is one or more of the following mixtures of organic high molecular materials: styrene-butadiene-styrene triblock copolymer (SBS), linear tri-block copolymer (SEBS), polystyrene-polyisoprene-polystyrene triblock copolymer (SIS);

[0010] The solvent is one or more of the following mixtures of solvents: water, N-N dimethylformamide (DMF), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dichloromethane (DCM), dichloroethane (DCE);

[0011] The prepared spinning solution is used for centrifugal spinning, a high-power light source of 1000W-1500W is used for irradiation during the spinning process, the light source directly irradiates the spinneret and the spun fiber, the spinning environment temperature is rapidly increased during the irradiation process, the volatilization of the solvent on the fiber after the fiber is formed is accelerated, and the porous structure of the fiber is constructed; a polymer micro / nano fiber membrane is obtained;

[0012] (2) Low-temperature cold plasma modification: the prepared polymer micro / nano fiber membrane is placed in a cold plasma modification treatment instrument for oxygen plasma modification glow discharge treatment, the treatment pressure is 40Pa±5Pa, the treatment power is 80W±10W, and the time is 100s-140s;

[0013] (3) Preparation of super-hydrophilic fiber membrane: the fiber membrane after the cold plasma modification treatment is subjected to hydrophilic modification in an acrylamide (AM) solution;

[0014] (4) Preparation of unidirectional wetting fiber membrane: the polymer micro / nano fiber membrane obtained in step (1) and the super-hydrophilic fiber membrane prepared in step (3) are subjected to hot-pressing compounding to obtain a unidirectional wetting micro / nano fiber membrane.

[0015] The principle of the application is that the polymer and the solvent are mixed for centrifugal spinning, the solvent is rapidly volatilized to form pores to obtain a porous fiber membrane product. During the spinning process, a high-power light source is used for irradiation, the light source directly irradiates the spinneret and the spun fiber, the spinning environment temperature is rapidly increased during the irradiation process, the volatilization of the solvent on the fiber after the fiber is formed is accelerated, and the porous structure of the fiber is constructed; the SBS porous membrane contains hydroxyl radicals through low-temperature cold plasma modification, the SBS porous membrane and acrylamide are subjected to radical graft polymerization under the protection of nitrogen, the SBS porous membrane is endowed with super-hydrophilicity, and then a unidirectional wetting fiber membrane is prepared by hot-pressing compounding.

[0016] Preferably, in step (1), the spinning solution is composed of solute SBS and solvent DCM, and the mass fraction of SBS in the spinning solution is 20wt%.

[0017] As preferred, the diameter of the spinning hole is 0.4 mm and the spinning speed is 8000 rpm / min in the centrifugal spinning of step (1).

[0018] As preferred, the oxygen purity is 99.99%, the plasma treatment pressure is 40 Pa, the power is 80 W and the time is 120 s in step (2).

[0019] As preferred, the concentration of AM in the acrylamide (AM) solution is 10 wt%-15 wt% in step (3); the hydrophilic modification temperature is 60-80 ℃ and the time is 15-45 min under nitrogen protection.

[0020] As preferred, the concentration of AM in the acrylamide (AM) solution is 10 wt% in step (3); the hydrophilic modification temperature is 80 ℃ and the time is 45 min.

[0021] As preferred, the hot-pressing equipment is a hot press machine, the composite temperature is 90 ℃ and the time is 10 s in step (4).

[0022] As preferred, the thickness of the polymer micro / nano fiber membrane prepared in step (1) is 0.2 mm±0.01 mm.

[0023] As preferred, the light source is a news lamp, the color temperature of the news lamp is 2800-5600 k and the power is 1300 W in the centrifugal spinning of step (1).

[0024] A unidirectional wetting micro / nano fiber membrane prepared by the preparation method.

[0025] The unidirectional wetting fiber membrane is constructed by centrifugal spinning and hydrophilic modification by using the waterproofness and elasticity of styrene-butadiene-styrene block copolymer (SBS). The asymmetric wetting unidirectional wetting fiber membrane is prepared by using the gas-liquid plasma modification method to prepare super-hydrophilic fiber membrane and then using the hot-pressing method. The key point (difficulty) is the regulation of the thickness of the hydrophobic side fiber membrane, which is a key factor affecting the unidirectional wetting effect.

[0026] Compared with the prior art, the present application has the following advantages: high centrifugal spinning yield, simple equipment, easy operation, fiber regulation can be adjusted by controlling process parameters such as speed, spinning liquid concentration, spinning hole diameter and collection rod distance to obtain the required fiber diameter and different specific surface area. The prepared fiber membrane has excellent unidirectional wetting effect by using the oxygen plasma pretreatment and then grafting acrylamide (AM) monomer and finally combining the unmodified SBS porous membrane. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1SEM image of SBS fiber film after grafting acrylamide (AM) monomer of Example 1-5;

[0028] Figure 2 SEM image of SBS fiber film after grafting acrylamide (AM) monomer of Example 6;

[0029] Figure 3 Grafting rate of monomer at different grafting time at grafting temperature of 80℃. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed description is illustrative only, and is intended to provide further description in connection with the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0031] It is also important to note that the terms "including", "comprising", and / or "having" as used herein are specifically intended to be open-ended and also to mean including, but not limited to. As used herein, the singular forms "a", "an" and / or "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, to the extent that any term is defined by a citation of a document, the definition is intended to be limited to the meaning of that term in the cited document at the time of filing this application.

[0032] In the present application, all parts, percentages and ratios are by weight unless otherwise indicated. The apparatus and materials used in the present application are commercially available or otherwise known in the art. The methods used in the following examples are conventional in the art unless otherwise indicated.

[0033] Centrifugal spinning machine (SMEKO Intelligent Manufacturing Co., Ltd.), styrene-butadiene-styrene block copolymer (SBS, American Kraton Corporation), dichloromethane (DCM, analytical pure, Hangzhou Gaosheng Fine Chemical Co., Ltd.), acrylamide (AM, analytical pure, Shanghai Maikelin Biotechnology Co., Ltd.);

[0034] Cold plasma treatment instrument, HD-1 type, Changzhou Changtai Plasma Technology Development Co., Ltd. The cold plasma treatment instrument includes a vacuum cavity, a radio frequency power generator, a pressure indicator and an automatic timing alarm.

[0035] high-power news lamp, Color temperature is 2800-5600k, power is 1300W.

[0036] The centrifugal spinning device used for centrifugal spinning includes a motor, a spinning head and a collection rod. The spinning head is installed at the top of the rotating shaft of the motor and is driven to rotate by the motor. The spinning head has a cavity for accommodating spinning solution. The top of the spinning head is provided with a liquid injection port, and the side wall of the spinning head is provided with a spinning hole communicating with the cavity. The collection rod is arranged around the spinning head.

[0037] When centrifugal spinning, the spinning speed is adjusted to 8000 rpm / min, and a high-power light source is used to irradiate the spinneret and the spun fibers directly. The porous micro / nano fiber membrane is collected by a collection rod. The irradiation process rapidly increases the spinning environment temperature, accelerates the volatilization of the solvent on the fibers after the fibers are formed, and is beneficial to the construction of the porous structure of the fibers.

[0038] Example 1

[0039] A centrifugal spinning method for preparing a one-way moisture-conducting micro / nano fiber membrane, and the specific steps are as follows:

[0040] (1) Accurately weigh the polymer with an analytical balance: 2 g of styrene-butadiene-styrene block copolymer (SBS), and 8 g of dichloromethane (DCM) as a solvent are placed in a 20 ml sample bottle, which is sealed with a raw material band. Stir at room temperature for 4 h to obtain a uniformly dispersed spinning solution of SBS. The prepared spinning solution is injected into the spinneret of the centrifugal spinning machine, and then under the irradiation of a high-power news lamp under the irradiation of a high-power news lamp Centrifugal spinning is performed to obtain a SBS porous membrane;

[0041] (2) The SBS porous membrane is washed with water and dried to obtain a smooth fiber membrane surface. Then the prepared SBS porous membrane is attached to a glass plate and placed in the vacuum chamber of a cold plasma treatment instrument; turn on the power switch, evacuate, control the pressure in the vacuum chamber to 10 Pa, and then introduce oxygen, backflow 2-3 times. Adjust the gas valve to control the pressure in the vacuum chamber to 40 Pa, turn on the plasma radio frequency power button, and after the plasma discharges, turn on the timing button, the treatment time is 120 s, the power is 80 w, then close the oxygen valve and turn off the power.

[0042] (3) Accurately weigh 10 g of acrylamide (AM) with an analytical balance, place it in a 250 ml beaker, add 90 g of deionized water, heat to 60℃, then place the plasma-treated SBS porous membrane in the working solution, and graft for 45 min under the protection of nitrogen. Take out and rinse with anhydrous ethanol, and then dry at 60℃.

[0043] (4) The untreated SBS porous membrane and the SBS fiber membrane grafted with acrylamide monomers are compounded by a hot-pressing method to obtain a one-way moisture-conducting fiber membrane.

[0044] According to the standard GB / T12704.2-2009, the moisture permeation flux of the fiber membrane from the hydrophobic layer to the hydrophilic layer is 7 kg / m 2 / d, and the moisture permeation flux from the hydrophilic layer to the hydrophobic layer is 0.5 kg / m 2 / d.

[0045] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 630, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer is -530.

[0046] Example 2

[0047] A centrifugal spinning method for preparing a one-way moisture-conducting micro / nano fiber membrane, the specific steps are as follows:

[0048] (1) Accurately weigh the polymer with an analytical balance: 2g of styrene-butadiene-styrene block copolymer (SBS), solvent: 8g of dichloromethane (DCM), place in a 20ml sample bottle, seal the sample bottle with raw material tape, stir at room temperature for 4h to finally prepare a uniformly dispersed spinning solution of SBS. The prepared spinning solution is injected into the spinneret of the centrifugal spinning machine, and then under the irradiation of a high-power news lamp Figure 1 Centrifugal spinning is carried out to obtain a SBS porous membrane;

[0049] (2) Wash and dry the SBS porous membrane to obtain a smooth fiber membrane surface. Then attach the prepared SBS porous membrane to a glass plate and place them together in the vacuum chamber of a cold plasma treatment instrument; turn on the power switch, evacuate, control the pressure in the vacuum chamber to 10Pa, and then introduce oxygen, backflow 2-3 times. Adjust the gas valve to control the pressure in the vacuum chamber to 40Pa, turn on the plasma radio frequency power button, and after the plasma discharges, turn on the timing button, the treatment time is 120s, the power is 80w, then close the oxygen valve and turn off the power.

[0050] (3) Accurately weigh 10g of acrylamide (AM) with an analytical balance, place it in a 250ml beaker, add 90g of deionized water, heat to 70℃, then place the plasma-treated SBS porous membrane in the working solution, under the protection of nitrogen for 45min, take out and rinse with anhydrous ethanol, then dry at 60℃.

[0051] (4) The untreated SBS porous membrane and the SBS fiber membrane grafted with acrylamide monomer are compounded by hot pressing to obtain a one-way moisture-conducting fiber membrane.

[0052] According to the national standard GB / T12704.2-2009, the moisture permeation flux of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 7.5kg / m 2 / d, and the moisture permeation flux along the hydrophilic layer to the hydrophobic layer is 0.4kg / m 2 / d.

[0053] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 700, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer is -600.

[0054] Example 3

[0055] A centrifugal spinning method for preparing a one-way moisture-conducting micro / nanofiber membrane, the specific steps are as follows:

[0056] (1) Accurately weigh the polymer with an analytical balance: 2 g of styrene-butadiene-styrene block copolymer (SBS), solvent: 8 g of dichloromethane (DCM), place in a 20 ml sample bottle, seal the sample bottle with raw material tape, stir at room temperature for 4 h, and finally prepare a uniformly dispersed spinning solution of SBS. The prepared spinning solution is injected into the spinneret of the centrifugal spinning machine, and then Figure 2 Figure 2 Centrifugal spinning is performed to obtain a SBS porous membrane;

[0057] (2) The SBS porous membrane is washed with water and dried to obtain a smooth fiber membrane surface. Then the prepared SBS porous membrane is attached to a glass plate and placed in the vacuum chamber of a cold plasma treatment instrument; turn on the power switch, evacuate, control the pressure in the vacuum chamber to 10 Pa, and then introduce oxygen, backflow 2-3 times. Adjust the gas valve to control the pressure in the vacuum chamber to 40 Pa, turn on the plasma radio frequency power button, and after the plasma discharges, turn on the timing button, the treatment time is 120 s, the power is 80 w, turn off the oxygen valve and then turn off the power.

[0058] (3) Accurately weigh 10 g of acrylamide (AM) with an analytical balance, place it in a 250 ml beaker, add 90 g of deionized water, heat to 80℃, then place the plasma-treated SBS porous membrane in the working solution, and graft for 45 min under the protection of nitrogen, then rinse with anhydrous ethanol, and then dry at 60℃.

[0059] (4) The untreated SBS porous membrane and the SBS fiber membrane grafted with acrylamide monomers are compounded by hot pressing to obtain a one-way moisture-conducting fiber membrane.

[0060] According to the national standard GB / T12704.2-2009, the moisture permeation flux of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 9 kg / m 2 / d, and the moisture permeation flux along the hydrophilic layer to the hydrophobic layer is 0.3 kg / m 2 / d.

[0061] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 1300, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer is -1250.

[0062] Example 4

[0063] A one-way moisture management fiber membrane was prepared in this example, the only difference from Example 3 was that the grafting time was 15 min.

[0064] According to the national standard GB / T12704.2-2009, the moisture permeation flux of the fiber membrane along the hydrophobic layer to the hydrophilic layer was 5 kg / m 2 / d, and the moisture permeation flux along the hydrophilic layer to the hydrophobic layer was 0.5 kg / m 2 / d.

[0065] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer was 450, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer was -400.

[0066] Example 5

[0067] A one-way moisture management fiber membrane was prepared in this example, the only difference from Example 3 was that the grafting time was 30 min.

[0068] According to the national standard GB / T12704.2-2009, the moisture permeation flux of the fiber membrane along the hydrophobic layer to the hydrophilic layer was 7 kg / m 2 / d, and the moisture permeation flux along the hydrophilic layer to the hydrophobic layer was 0.5 kg / m 2 / d.

[0069] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer was 965, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer was -900.

[0070] Example 6

[0071] A one-way moisture management fiber membrane was prepared in this example, the only difference from Example 3 was that the grafting temperature was 90℃ and the grafting time was 45 min.

[0072] According to the national standard GB / T12704.2-2009, the moisture permeation flux of the fiber membrane along the hydrophobic layer to the hydrophilic layer was 8 kg / m 2 / d, and the moisture permeation flux along the hydrophilic layer to the hydrophobic layer was 0.4 kg / m 2 / d.

[0073] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer was 1000, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer was -800.

[0074] Example 7

[0075] A one-way moisture management fiber membrane was prepared in this example, the only difference from Example 3 was that the grafting time was 60 min.

[0076] According to the national standard GB / T12704.2-2009, the moisture permeability of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 8.8 kg / m 2 / d, and the moisture permeability along the hydrophilic layer to the hydrophobic layer is 0.4 kg / m 2 / d.

[0077] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 1265, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer is -1000.

[0078] Comparative Example 1

[0079] A one-way moisture transfer fiber membrane was prepared in this comparative example, which was different from Example 3 in that it was not treated in step (2). Its performance was tested under standard conditions.

[0080] According to the national standard GB / T12704.2-2009, the moisture permeability of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 1 kg / m 2 / d, and the moisture permeability along the hydrophilic layer to the hydrophobic layer is 0.6 kg / m 2 / d.

[0081] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 150, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer is -20.

[0082] Comparative Example 2

[0083] A one-way moisture transfer material was prepared in this comparative example, which was different from Example 3 in that nitrogen protection was not used in step (3). Its performance was tested under standard conditions.

[0084] According to the national standard GB / T12704.2-2009, the moisture permeability of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 6 kg / m 2 / d, and the moisture permeability along the hydrophilic layer to the hydrophobic layer is 0.6 kg / m 2 / d.

[0085] According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 930, and the one-way transfer index along the hydrophilic layer to the hydrophobic layer is -750.

[0086] Conclusion

[0087] Example 1-5 Step (3) was prepared by using different grafting temperature and time, which were 60℃ 45min, 70℃ 45min, 80℃ 45min, 80℃ 15min, 80℃ 30min, respectively. The SEM images of SBS fiber membrane after grafting acrylamide (AM) monomer in Example 1-5 were shown in Figure 3 Example 1. The grafting rate of acrylamide monomer on the fiber surface prepared at 60℃ for 45min was very low. Example 2. The acrylamide monomer on the fiber surface began to form a more complete monomer film prepared at 70℃ for 45min. Example 3. The grafting effect on the fiber surface was the best prepared at 80℃ for 45min.

[0088] Figure 3 Example 6. The grafting temperature was 90℃ and the grafting time was 45min. According to under the irradiation of a high-power news lamp , the fiber membrane surface began to appear damage when the grafting temperature was 90℃, which affected the mechanical properties of the fiber.

[0089] ​ The grafting rate of monomer under different grafting time at 80℃ was shown in Example 6 and Example 3, which only differed in grafting time for 60min. According to ​ , the grafting rate of monomer did not change significantly with the increase of grafting time.

[0090] From the SEM images, we found that when the grafting temperature was 60℃ and the time was 45min, the grafting effect of acrylamide on SBS fiber was not ideal. When the temperature increased to 70℃, the SBS fiber surface began to cover a layer of monomer film, and when the temperature further increased to 80℃, the grafting success rate increased significantly. This result was attributed to the enhanced interaction between monomer and fiber surface at high temperature, which improved the efficiency of free radical reaction, and the grafting rate gradually increased with the increase of time. Therefore, the grafting temperature of 85℃ and the time of 45min were selected as the optimal treatment parameters.

[0091] From the above test results, it can be seen that the unidirectional moisture transfer micro / nano fiber membrane prepared in Example 3 has the best effect, with the highest moisture flux (hydrophobic layer to hydrophilic layer) of 9kg / m 2 / d and the lowest moisture flux (hydrophilic layer to hydrophobic layer) of 0.3kg / m 2 / d. At the same time, the unidirectional transfer index (hydrophobic layer to hydrophilic layer) is also the highest, reaching 1300, while the unidirectional transfer index (hydrophilic layer to hydrophobic layer) is the lowest, reaching -1250. The grafting time of acrylamide (AM) in Example 3 was 45min and the temperature was 80℃, which helped to more fully graft the reaction, thereby improving the hydrophilic performance of the fiber membrane.

[0092] Example 8 Single Factor Test for Thickness Control of SBS Porous Membrane

[0093] The preparation of SBS porous membrane is similar to that in Example 3. The specific steps are as follows: 2 g of polymer (SBS) and 8 g of solvent (DCM) are accurately weighed using an analytical balance and placed in a 20 ml sample bottle. The sample bottle is sealed with raw tape and stirred at room temperature for 4 h to obtain a spinning solution with uniform SBS dispersion. The obtained spinning solution is injected into the spinneret of a centrifugal spinning machine, and then ​ Centrifugal spinning was performed to obtain an SBS porous membrane.

[0094] This example discusses the thickness of the SBS porous membrane as a single factor and tests its performance under standard conditions.

[0095] When the thickness of the SBS porous membrane is 0.10 mm, the moisture permeability of the fiber membrane from the hydrophobic layer to the hydrophilic layer is 9.5 kg / m according to the positive cup method of the national standard GB / T12704.2-2009. 2 / d, the moisture permeability from the hydrophilic layer to the hydrophobic layer is 6.5kg / m 2 According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane from the hydrophobic layer to the hydrophilic layer is 1000, and the one-way transfer index from the hydrophilic layer to the hydrophobic layer is 600.

[0096] When the thickness of the SBS porous membrane is 0.15 mm, the moisture permeability of the fiber membrane from the hydrophobic layer to the hydrophilic layer is 9 kg / m according to the positive cup method of the national standard GB / T12704.2-2009. 2 / d, the moisture permeability from the hydrophilic layer to the hydrophobic layer is 4.3kg / m 2 According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane from the hydrophobic layer to the hydrophilic layer was 1130, and the one-way transfer index from the hydrophilic layer to the hydrophobic layer was 450.

[0097] When the thickness of the SBS porous membrane is 0.2 mm, the moisture permeability of the fiber membrane from the hydrophobic layer to the hydrophilic layer is 9.3 kg / m according to the positive cup method of the national standard GB / T12704.2-2009. 2 / d, the moisture permeability from the hydrophilic layer to the hydrophobic layer is 0.2kg / m 2 According to the national standard GB / T21655.2-2019, the one-way transfer index of the fiber membrane from the hydrophobic layer to the hydrophilic layer is 1350, and the one-way transfer index from the hydrophilic layer to the hydrophobic layer is -1300.

[0098] The water vapor flux of the SBS porous membrane along the hydrophobic layer to the hydrophilic layer is 0.25 kg / m 2 / d, and the water vapor flux along the hydrophilic layer to the hydrophobic layer is 0.3 kg / m 2 / d. According to the national standard GB / T21655.2-2019, the one-way transmission index of the fiber membrane along the hydrophobic layer to the hydrophilic layer is 0, and the one-way transmission index along the hydrophilic layer to the hydrophobic layer is -1200.

[0099] In Example 8, we explored the effect of different thicknesses of hot-pressed untreated SBS porous membranes on the one-way moisture transport performance. The results showed that when the thickness of the SBS porous membrane was 0.1 mm and 0.15 mm, although the water transport capacity of the fiber membrane along the hydrophobic layer to the hydrophilic layer was good, the water transferred to the hydrophilic layer was easy to flow back to the hydrophobic layer due to the small thickness of the hydrophobic layer, and the one-way transmission performance of the prepared fiber membrane was poor. When the thickness of the SBS porous membrane increased to 0.2 mm, the fiber membrane had the best one-way moisture transport performance, with the highest water vapor flux (hydrophobic layer to hydrophilic layer) of 9.3 kg / m 2 / d and the lowest water vapor flux (hydrophilic layer to hydrophobic layer) of only 0.2 kg / m 2 / d. At the same time, its one-way transmission index (hydrophobic layer to hydrophilic layer) was the highest, reaching 1350, and the one-way transmission index (hydrophilic layer to hydrophobic layer) was the lowest, reaching -1300. When the thickness of the SBS porous membrane was 0.25 mm, water could only stay on the hydrophobic side of the fiber membrane and could not penetrate to the hydrophilic side, and the fiber membrane completely lost the one-way moisture transport ability.

[0100] In summary, when the thickness of the SBS porous membrane is 0.2 mm, the one-way moisture transport micro / nanofiber membrane prepared has the best effect, achieving high-efficiency one-way moisture transport performance.

[0101] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part.

[0102] The one-way moisture-conducting micro / nanofiber membrane and the centrifugal spinning preparation method thereof are described in detail. The principles and implementation manners of the present application are described by using specific examples. The above description of the examples is only used to help understand the method of the present application and its core idea. It should be pointed out that, for those skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A centrifugal spinning method for preparing a unidirectional moisture-conducting micro / nanofiber membrane, characterized in that The method comprises the following steps: (1) Centrifugal spinning: The polymer is mixed with the solvent and dispersed evenly to obtain a spinning solution. The mass concentration of the polymer is 20wt%-24wt%; The polymer is a mixture of one or more of the following organic polymer materials: styrene-butadiene-styrene triblock copolymer (SBS), linear triblock copolymer SEBS, polystyrene-polyisoprene-polystyrene triblock copolymer (SIS); The solvent is a mixture of one or more of the following solvents: water, N-dimethylformamide (DMF), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dichloromethane (DCM), and dichloroethane (DCE); The prepared spinning solution is used for centrifugal spinning. During the spinning process, a high-power light source of 1000 W to 1500 W is used for irradiation. The light source directly irradiates the spinneret and the ejected fibers. During the irradiation process, the spinning environment temperature is rapidly increased, which accelerates the volatilization of the solvent on the fibers after the fibers are formed and constructs a porous fiber structure; thus, a polymer micro / nano fiber membrane is obtained. (2) Low-temperature cold plasma modification: The prepared polymer micro / nanofiber membrane is placed in a cold plasma modification treatment apparatus for oxygen plasma modification glow discharge treatment at a treatment pressure of 40 Pa ± 5 Pa, a treatment power of 80 W ± 10 W, and a treatment time of 100 s-140 s; (3) Preparation of super-hydrophilic fiber membrane: The fiber membrane after cold plasma modification is hydrophilically modified in an acrylamide (AM) solution; the concentration of AM in the acrylamide (AM) solution is 10wt%-15wt%; the fiber membrane is hydrophilically modified and grafted under nitrogen protection, the hydrophilic modification temperature is 60-80℃, and the time is 15-45 min; (4) Preparation of a unidirectional moisture-conducting fiber membrane: The polymer micro / nano fiber membrane obtained in step (1) and the super-hydrophilic fiber membrane obtained in step (3) are composited by hot pressing to obtain a unidirectional moisture-conducting micro / nano fiber membrane.

2. The preparation method according to claim 1, wherein: In step (1), the spinning solution consists of solute SBS and solvent DCM, and the mass fraction of SBS in the spinning solution is 20 wt%.

3. The preparation method according to claim 1, wherein: During the centrifugal spinning in step (1), the diameter of the spinning hole is 0.4 mm and the spinning speed is 8000 rpm.

4. The preparation method according to claim 1, wherein: In step (2), the oxygen purity is 99.99%, the plasma treatment pressure is 40 Pa, the power is 80 W, and the time is 120 s.

5. The preparation method according to claim 1, wherein: In step (3), the concentration of acrylamide (AM) in the AM solution is 10 wt %; the hydrophilic modification temperature is 80 ° C and the time is 45 min.

6. The preparation method according to claim 1, wherein: In step (4), the hot pressing compounding equipment is a heat press machine, the compounding temperature is 90°C, and the time is 10 seconds.

7. The preparation method according to claim 1, wherein: The thickness of the polymer micro / nanofiber membrane prepared in step (1) is 0.2 mm ± 0.01 mm.

8. The preparation method according to claim 1, wherein: During the centrifugal spinning in step (1), the light source is provided by a news light, the color temperature of the news light is 2800-5600 K, and the power is 1300 W.

9. A unidirectional moisture-conducting micro / nanofiber membrane prepared by the preparation method according to claim 1.

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