A sponge-like interconnected network structure high air and moisture permeable protective film material and a preparation method thereof

Abstract

The application discloses a sponge-like interconnected network structure high-air-permeable and high-moisture-permeable protective film material and a preparation method thereof. The preparation method comprises the following steps: preparing casting solution by mixing hygroscopic inorganic salt, polymer, fluorine-containing polymer and solvent; coating the casting solution on a substrate to obtain an initial wet film, then immersing the initial wet film in a coagulation bath to perform phase inversion, then spraying finishing liquid containing hydrophobic finishing agent and nanoparticles, and drying to obtain the sponge-like interconnected network structure high-air-permeable and high-moisture-permeable protective film material. The micro-nano interconnected network structure is prepared by introducing micron-sized inorganic salt and fluorine-containing polymer in a synergistic manner, the pore channel is a vertical interconnected pore channel, the horizontal direction is a dense micro-nano pore structure, and the synergistic regulation of the interconnected pore channel and the gradient pore structure significantly improves the air permeability and moisture permeability of the material; the horizontal micro-nano pore structure and the addition of the fluorine-containing polymer endow the material with liquid barrier property. The application meets the actual application requirements in the individual protection field by maintaining the protection performance and taking into account the high air permeability and high moisture permeability of the material.

Description

Technical Field

[0001] This invention relates to a highly breathable and moisture-permeable protective membrane material with a sponge-like interconnected network structure and its preparation method, belonging to the field of micro-nano protective materials technology. Background Technology

[0002] Breathable and moisture-permeable protective membranes hold immense potential in the field of personal protective equipment (PPE) and play a crucial role in protecting life and health. With rising living standards and hygiene levels, the demand for safe and comfortable protective fabrics is constantly increasing. In addition to good protective performance, medical protective materials must also possess excellent breathability and moisture permeability to ensure wearer comfort. Over the past few decades, medical protective clothing has made significant progress in protection, breathability, and thermal and moisture comfort. However, the critical balance between protective capability and wearing comfort has been largely overlooked, which is closely related not only to the comfort of healthcare workers but also to their work efficiency.

[0003] Currently, medical protective clothing with excellent barrier properties can be produced using woven, knitted, and nonwoven technologies. Woven fabrics, with their surface chemical finishing or the addition of barrier membranes, are widely used in reusable medical clothing due to their simple production process and high cost-effectiveness. The non-solvent-induced phase separation (NIPS) membrane fabrication method, invented in the 1960s, is a highly efficient membrane fabrication method. Asymmetric membrane structures prepared using this method exhibit good selective permeation performance and easily adjustable pore structures, making it a commonly used method for researching and commercially producing polymer-coated membranes. Using inorganic salts as pore-forming agents allows for precise control of the material's pore size and porosity. Furthermore, inorganic salts are chemically stable and do not readily react adversely with other materials, ensuring the purity and performance of the porous material. In addition, inorganic salts are water-soluble and can be removed through simple water washing during post-processing, avoiding the influence of residual pore-forming agents on material properties.

[0004] Patent CN112918056B discloses a method for preparing a waterproof and breathable membrane. The membrane comprises a medical nonwoven fabric, a hydrophilic breathable membrane, and an antibacterial waterproof membrane. The antibacterial waterproof membrane and the medical nonwoven fabric are respectively attached to the upper and lower surfaces of the hydrophilic breathable membrane. To improve wearing comfort, medical nonwoven fabric is added to the inside of the hydrophilic breathable membrane to avoid adhesion; however, this has a certain impact on the membrane's breathability, and the improvement in breathability is not significant.

[0005] Patent CN111019332B discloses a method for preparing a polyurethane waterproof and breathable membrane, which is mainly composed of polyurethane resin, a pore-forming agent, inorganic fillers, and organic solvents. The surface of the polyurethane waterproof and breathable membrane is formed using a dry process, resulting in good moisture permeability. However, the membrane prepared by this technique does not form a connected pore structure, leading to insufficient air permeability, and it also lacks the ability to block other liquids (such as oil, synthetic blood, and alcohol).

[0006] Patent CN107556715B discloses a waterproof and breathable membrane and its preparation method. It uses biomass materials, a renewable resource, to reduce reliance on non-renewable petroleum resources, and polyester has good biodegradability. However, to meet environmental protection requirements, the pore size of the waterproof and breathable membrane produced by this method is relatively small, limiting its application in outdoor protection.

[0007] Patent CN113430676B discloses a micro / nanofiber for medical and health protection and its preparation method. First, PP, a polar polymer, and additives are mixed in an extruder for melt mixing, plasticizing, and granulation to prepare PP alloy particles. Then, supercritical CO2 is used for dissolution and infiltration to obtain a homogeneous PP alloy / supercritical fluid system. Finally, melt electrospinning is used to prepare a multi-level structured, low-resistance, and high-efficiency PP composite micro / nanofiber membrane. This method uses safe and environmentally friendly melt electrospinning instead of solution electrospinning, avoiding the use of toxic and harmful organic solvents during the spinning process.

[0008] However, current phase separation methods for preparing microporous membranes neglect the material's air permeability and moisture permeability. Prolonged wear of protective clothing with poor air and moisture permeability can lead to moisture and heat buildup, causing skin allergies, heatstroke, and even fainting, while also increasing fatigue and reducing work efficiency. Therefore, optimizing the bulk structure of membrane materials to improve their air and moisture permeability, while simultaneously enhancing their liquid barrier properties, is of great significance for practical applications in personal protective equipment. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by providing a highly permeable and moisture-permeable protective membrane material with a sponge-like interconnected network structure and its preparation method. Specifically, this invention provides a phase transformation technology applicable to a wide range of polymer raw materials that can prepare stable microporous membranes with a sponge-like interconnected network structure without templates. The microporous membrane prepared by this method has excellent air and moisture permeability and liquid barrier properties.

[0010] To achieve the above objectives, the present invention provides a method for preparing a highly breathable and moisture-permeable protective membrane material with a sponge-like interconnected network structure, comprising the following steps:

[0011] Step 1: Prepare a casting solution by mixing hygroscopic inorganic salts, polymers, fluoropolymers, and solvents;

[0012] Step 2: Apply the casting solution to the substrate to form an initial wet film;

[0013] Step 3: Immerse the initial wet film obtained in Step 2 into a coagulation bath for phase transformation to obtain a microporous membrane with a sponge-like interconnected network structure.

[0014] Step 4: Mix the hydrophobic finishing agent and nanoparticles to prepare a spraying liquid, spray it onto the microporous membrane obtained in step 3, and dry it to obtain the final product.

[0015] In the above preparation method, the use of hygroscopic inorganic salts mixed with polymers is beneficial for phase transformation and pore formation. First, since the coagulation bath used in the phase transformation process is mainly composed of water, the solubility of inorganic salts makes it easier to form micron-sized pores. Second, although the hygroscopic inorganic salts dissolve during the preparation process, their ionic form after dissolving in water promotes the transformation and also changes the material properties, improving moisture permeability. Furthermore, the size of the inorganic salts is controllable during the transformation process; those skilled in the art can control the size of micron-sized or nano-sized inorganic salts according to requirements. The dissolution process of the inorganic salts in solvents and water can be controlled; excessive inorganic salts are more likely to form micron-sized pores, while a small amount of inorganic salts is more likely to form nanopores.

[0016] In the above preparation method, a hygroscopic inorganic salt is added to the casting solution. Hygroscopic inorganic salts usually have good solubility and can be dissolved and carried out during phase transformation in an aqueous coagulation bath to form a microporous membrane with a micro-nano porous structure. The self-assembly of the microporous membrane will obtain a sponge-like microporous membrane material with high specific surface area and high porosity. The additional capillary force generated by the high specific surface area and high porosity structure is expected to improve its moisture absorption rate and greatly increase its contact area with air, thereby enhancing the material's moisture permeability, moisture diffusion rate, and drying rate, and thus endowing the material with excellent air permeability and moisture permeability.

[0017] Furthermore, the introduction of fluoropolymers in the above preparation method alters the bulk properties of the casting solution. The introduction of highly energetic carbon-fluorine bonds, combined with the "shielding and protective effect" of fluorine atoms on carbon atoms, significantly improves the polymer's thermal stability, liquid repellency, and chemical corrosion resistance. Additionally, fluorine atoms possess extremely high electronegativity and a small atomic radius; introducing fluorine atoms into the polymer molecule allows for fine-tuning and modification of the molecular structure, blocking readily soluble sites of inorganic salts and improving the dissolution pathway and rate. Simultaneously, intermolecular hydrogen bonding effectively delays the interaction time of inorganic salts during phase transformation, increasing the molecular utilization and selectivity of the polymer solution during phase transformation, inducing phase transition and solidification, and promoting rapid self-assembly to form a sponge-like structure.

[0018] Preferably, the hygroscopic inorganic salt in step 1 is selected from at least one of inorganic magnesium salt, inorganic calcium salt, inorganic sodium salt, inorganic potassium salt, inorganic copper salt, and inorganic ammonium salt;

[0019] The solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, tetrahydrofuran, N-methylpyrrolidone, chloroform, methanol, ethanol, isopropanol, deionized water, acetone, dichloromethane, formic acid, acetic acid, dimethyl sulfoxide, diethyl ether, toluene, trichloroacetic acid, and trifluoroacetic acid.

[0020] More preferably, the hygroscopic inorganic salt is selected from at least one of calcium chloride, magnesium chloride, potassium chloride, sodium sulfate, sodium chloride, copper sulfate, calcium oxide, ammonium sulfate, sodium hypochlorite, and sodium hydroxide.

[0021] Preferably, the polymer in step 1 is selected from at least one of polyurethane, thermoplastic polyurethane, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polystyrene, polycaprolactone, polyamide 6, polyamide 66, polyimide and polyethylene terephthalate.

[0022] The fluoropolymer is at least one of fluorinated polyurethane (FPU), fluorinated polycarbonate (FPC), fluorinated acrylate (FAA) polymer, perfluoropolyether (PFPE), fluorinated polyester (FPET), fluorinated polyarylene ether (FPSF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA), trifluorochloroethylene-ethylene copolymer (ECTFE), polytrifluorochloroethylene (PCTFE), perfluorosulfonic acid (PFSA), fluorinated polyimide (FPI), perfluoro-2,2-dimethyl-1,3-dioxolane-tetrafluoroethylene (PDD-TFE) copolymer, trifluorochloroethylene-vinyl ether copolymer (FEVE), perfluoroethylene propylene (FEP), polyvinyl fluoride (PVF), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV).

[0023] Preferably, in the casting solution obtained in step 1, the polymer content is 8-20% by mass, the mass fraction ratio of polymer to hygroscopic inorganic salt is 9:1-5:5, and the mass content of fluoropolymer is 1-10% by mass.

[0024] The viscosity of the casting solution is 1–10 Pa·s. In the preparation method of this invention, the prepared casting solution has a relatively low viscosity, which is more conducive to the phase transformation of the casting solution into pores, unlike traditional non-solvent phase separation techniques. The viscosity of the casting solution is jointly adjusted by the molecular weight of the polymer and the type of inorganic salt. Adding CaCl2 to the casting solution will decrease the viscosity, while adding LiCl will increase the viscosity. Therefore, those skilled in the art can select a suitable molecular weight polymer and the corresponding type of inorganic salt based on the viscosity parameters.

[0025] The reason why the viscosity of the casting solution is controlled to be 1 to 10 Pa·s is that the bulk property (viscosity) of the casting solution is a necessary condition for the formation of pore structure. If the viscosity of the casting solution is high, compared with the low viscosity solution, the high viscosity casting solution has a high solvent content and high intermolecular friction, so it is more difficult for solvent and non-solvent to diffuse in the same non-solvent coagulation bath. That is, the solution is easy to solidify, which is not conducive to the self-assembly of pore structure and it is not easy to generate a sponge-like network structure.

[0026] Preferably, the preparation method of the casting solution in step 1 includes:

[0027] Hygroscopic inorganic salts were added to the solvent and stirred continuously at room temperature. Then, polymers and fluoropolymers were added in sequence and stirred continuously at room temperature to obtain a uniform initial casting solution.

[0028] More preferably, the continuous stirring time is 2 to 20 hours, and the continued stirring time is 10 to 20 hours.

[0029] Preferably, the substrate in step 2 is selected from at least one of woven fabrics, knitted fabrics, nonwoven fabrics, and electrospun fiber membranes.

[0030] Preferably, the thickness of the film formed by scraping in step 2 is 100–2500 μm.

[0031] Preferably, the temperature of the coagulation bath in step 3 is 20–60°C, and the phase transformation time is 0.5–2 hours.

[0032] Preferably, the coagulation bath is at least one of water, a mixture of water and ethanol, and a mixture of water and DMF.

[0033] The reason why this invention controls the casting solution coating process parameters of "coating thickness 100-2500 μm, coagulation bath temperature 20-60℃, and phase transformation time 0.5-2 h" is that: these parameters determine whether a sponge-like structure can be formed. If the coating thickness is too high, the casting solution will not easily form interconnected channels during the transformation process within the same transformation time; the coagulation bath temperature affects the sponge-like shape. If the coagulation bath temperature is too low, it is not conducive to rapid forming during the transformation process. If the coagulation bath temperature is too high, the polymer properties will be unstable, thereby increasing the instability of the phase transformation and affecting the formation of the pore structure; the change in phase transformation time affects the pore-forming effect. If the time is too short, the transformation time is insufficient, the inorganic salts are not fully dissolved, the pore-forming effect is poor, and ultimately the material has poor air permeability. If the transformation time is too long, it will lead to waste of resources.

[0034] Preferably, the hydrophobic finishing agent in step 4 is a liquid, selected from at least one of fluorinated compounds (such as perfluoropolyether compounds PFPE), organosilicon resins (such as polydimethylsiloxane), fluorosilicone polymers (such as fluorosilicone acrylate copolymers), fluorocarbon polymers (such as polyperfluoropropylene), and Teflon.

[0035] The nanoparticles are selected from at least one of hydrophobic nano-silica, metal oxides (e.g., at least one of zinc oxide, titanium dioxide, copper oxide, and iron oxide), and metal nanoparticles (e.g., silver nanoparticles and / or gold nanoparticles).

[0036] Preferably, the mass content of nanoparticles in the spraying liquid of step 4 is 1-15%.

[0037] The present invention also provides a sponge-like interconnected network structure highly breathable and moisture-permeable protective membrane material prepared by the above preparation method.

[0038] The protective membrane material prepared by this invention has vertically connected channels and a dense micro-nanopore structure in the horizontal direction, with an average pore size of 1–15 μm. This microporous membrane has a large specific surface area and porosity, with a specific surface area >10 m². 2 / g, porosity >70%.

[0039] The protective membrane material prepared by this invention possesses excellent air permeability, moisture permeability, and reverse liquid permeation barrier properties because: the protective membrane material prepared by this invention has a sponge-like interconnected network structure in the vertical direction, forming a pore size gradient with the substrate in the thickness direction, and has an additional differential capillary effect, enabling rapid directional transport of moisture in the thickness direction. Therefore, the synergistic regulation of the interconnected channels and gradient pore structure in this invention significantly improves the air permeability and moisture permeability of the material; at the same time, the micro-nano pore structure in the horizontal direction and the addition of fluoropolymers, due to the dense pore structure and capillary resistance, hinder moisture transfer, thereby achieving liquid barrier properties.

[0040] This invention also provides the application of the above-mentioned sponge-like interconnected network structure highly breathable and moisture-permeable protective membrane material in the preparation of medical protective equipment.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) Unlike the traditional non-solvent phase separation method for preparing microporous membranes, in the preparation method of the present invention, the addition of hygroscopic inorganic salts makes the casting solution highly soluble. The solubility of inorganic salts makes it easier to form a polymer-poor phase. Under the competitive action of solubility and solvent and non-solvent diffusion, the self-assembly of the sponge-like interconnected network structure is induced, so as to realize the controllable preparation of highly permeable and moisture-permeable membrane materials.

[0043] (2) Unlike traditional non-solvent phase separation methods for preparing microporous membranes, in the preparation method of this invention, the addition of fluorinated polymers increases the carbon-fluorine bond content of the casting solution, which increases the electronegativity of the wet membrane during the phase transformation process. It utilizes the aggregation effect of fluorine atoms to form a membrane, which blocks the easily soluble sites of inorganic salts, improves the dissolution pathway and speed of molecules, and achieves the liquid repellency and chemical corrosion resistance of the membrane material.

[0044] (3) Existing non-solvent phase transformation technology for membrane materials neglects the air permeability and moisture permeability of the material, resulting in problems such as poor wearing comfort and low work efficiency during use. This invention prepares a micro-nano interconnected network structure by introducing micron-sized inorganic salts and fluorinated polymers in synergy, which maintains the protective performance while taking into account the high air permeability and high moisture permeability of the material, so as to meet the actual application needs in the field of personal protective equipment. Attached Figure Description

[0045] Figure 1 This is an electron microscope image of the surface of a sponge-like interconnected network pore structure protective membrane with high air and moisture permeability.

[0046] Figure 2 A cross-sectional electron microscope image of a protective membrane with a sponge-like interconnected network pore structure that has high air and moisture permeability.

[0047] Figure 3 The contact angle of water, synthetic blood, oil and ethanol aqueous solution within 300s for a sponge-like interconnected network pore structure protective membrane.

[0048] Figure 4 This study compares the air permeability and moisture permeability of a sponge-like interconnected network pore structure protective membrane with those of commercial protective products. Detailed Implementation

[0049] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0050] Unless otherwise specified, the materials and reagents used in the following examples are all commercially available products.

[0051] Example 1

[0052] A method for preparing a highly breathable and moisture-permeable protective membrane material with a sponge-like interconnected network structure, comprising the following specific steps:

[0053] Step 1: Dissolve the pore-forming agent CaCl2 in N,N-dimethylformamide and stir at room temperature for 6 hours until completely dissolved. Then, add polyurethane (PU, M...) sequentially. W Fluorinated polyurethane (FPU, Shanghai Taifu, catalog number: QF99-4) with different mass fractions (50,000 to 100,000) was stirred under constant magnetic stirring at room temperature for 10 hours to obtain a uniform PU / FPU / CaCl2 casting solution.

[0054] Step 2: Pour the casting solution obtained in Step 1 onto the woven fabric substrate, and use a coating tool to scrape the casting solution onto the substrate. Control the solution volume of the casting solution to 9 mL, and select a coating tool thickness of 250 μm to obtain a PU / FPU / CaCl2 wet film.

[0055] Step 3: Immediately immerse the wet membrane from Step 2 in a water coagulation bath for 3 hours to undergo phase transformation and deposit a porous PU / FPU framework. Subsequently, wash with ultrapure water and dry at 60°C to finally obtain a microporous membrane with a micro / nano network pore structure.

[0056] Step 4: Subsequently, the microporous membrane prepared in Step 3 was sprayed using a gravity-fed spray gun with a 1mm nozzle diameter. The operating air pressure was 4 Bar, the spraying distance was fixed at 20cm, and the spray gun flow rate was 30mL / min. -1 A highly permeable protective microporous membrane, PU / FPU@TRG, was obtained. The coating solution consisted of a fluorinated water- and oil-repellent finishing agent (TRG, a three-proof finishing agent, manufactured by Shanghai Xinwu Textile Technology Co., Ltd.) and hydrophobic nano-silica (CAS No.: 68611-44-9, manufactured by Shanghai Maclean Biochemical Technology Co., Ltd.), with a silica addition amount of 5 wt%.

[0057] The resulting sponge-like interconnected network structure high-permeability and moisture-permeable protective membrane material exhibits a tensile breaking strength of 65.56 MPa, a water pressure resistance of 12.86 kPa, a water contact angle of 131°, a synthetic blood contact angle of 126°, an oil contact angle of 104°, and an ethanol-water solution contact angle of 85°. Figure 3 As shown, the sponge-like interconnected micro-nano-scale network of pores in the microporous membrane facilitates the rapid transport of gas and moisture molecules, exhibiting superior gas and moisture permeability compared to commercially available protective clothing, with a breathability of 14.24 mm² / s. -1 The moisture permeability is 7.92 kg / m³. -2 d -1 ,like Figure 4 As shown.

[0058] Example 2

[0059] Step 1: Same as Step 1 in Example 1, except that the pore-forming agent is MgCl2.

[0060] Step 2: Same as step 2 in Example 1.

[0061] Step 3: Same as step 3 in Example 1.

[0062] Step 4: Same as step 4 in Example 1.

[0063] The resulting sponge-like interconnected network structure high-permeability and moisture-permeable protective membrane material exhibits a tensile breaking strength of 62.42 MPa, a water pressure resistance of 12.12 kPa, a water contact angle of 130°, a synthetic blood contact angle of 124°, an oil contact angle of 102°, and an ethanol-water solution contact angle of 81°. The sponge-like interconnected micro-nano-scale network of pores in the microporous membrane facilitates the rapid transport of gas and moisture molecules, achieving a permeability of 14.69 mm² / s. -1 The moisture permeability is 7.64 kg / m³. -2 d -1 .

[0064] Example 3

[0065] Step 1: Same as Step 1 in Example 1, except that the pore-forming agent is KCl.

[0066] Step 2: Same as step 2 in Example 1.

[0067] Step 3: Same as step 3 in Example 1.

[0068] Step 4: Same as step 4 in Example 1.

[0069] This yields a highly permeable and moisture-permeable protective membrane material with a sponge-like interconnected network structure. The tensile strength at break is 64.01 MPa, the water pressure resistance is 12.06 kPa, the water contact angle is 133°, the synthetic blood contact angle is 128°, the oil contact angle is 105°, and the ethanol-water solution contact angle is 89°. The sponge-like interconnected micro-nano network of pores in the microporous membrane facilitates the rapid transport of gas and moisture molecules, resulting in a permeability of 14.54 mm² / s. -1 The moisture permeability is 7.82 kg / m³. -2 d -1 .

[0070] Example 4

[0071] Step 1: Same as Step 1 in Example 1, except that the pore-forming agent is KCl.

[0072] Step 2: Same as step 2 in Example 1.

[0073] Step 3: Same as step 3 in Example 1.

[0074] Step 4: Same as step 4 in Example 1.

[0075] The resulting sponge-like interconnected network structure high-permeability and moisture-permeable protective membrane material exhibits a tensile breaking strength of 62.56 MPa, a water pressure resistance of 11.67 kPa, a water contact angle of 132°, a synthetic blood contact angle of 128°, an oil contact angle of 103°, and an ethanol-water solution contact angle of 85°. The sponge-like interconnected micro-nano-scale network of pores in the microporous membrane facilitates the rapid transport of gas and moisture molecules, achieving a permeability of 14.96 mm² / s. -1 The moisture permeability is 7.76 kg / m³. -2 d -1 .

[0076] Example 5

[0077] Step 1: Same as Step 1 in Example 1, except that the fluoropolymer is polyvinylidene fluoride.

[0078] Step 2: Same as step 2 in Example 1.

[0079] Step 3: Same as step 3 in Example 1.

[0080] Step 4: Same as step 4 in Example 1.

[0081] The resulting sponge-like interconnected network structure high-permeability and moisture-permeable protective membrane material exhibits a tensile breaking strength of 60.21 MPa, a water pressure resistance of 13.96 kPa, a water contact angle of 140°, a synthetic blood contact angle of 132°, an oil contact angle of 114°, and an ethanol-water solution contact angle of 94°. The sponge-like interconnected micro-nano-scale network of pores in the microporous membrane facilitates the rapid transport of gas and moisture molecules, achieving a permeability of 15.266 mm² / s. -1 The moisture permeability is 8.21 kg / m³. -2 d -1 .

[0082] Example 6

[0083] Step 1: Same as Step 1 in Example 1, except that the fluoropolymer is fluorinated polycarbonate.

[0084] Step 2: Same as step 2 in Example 1.

[0085] Step 3: Same as step 3 in Example 1.

[0086] Step 4: Same as step 4 in Example 1.

[0087] The resulting sponge-like interconnected network structure high-permeability and moisture-permeable protective membrane material exhibits a tensile breaking strength of 58.46 MPa, a water pressure resistance of 13.41 kPa, a water contact angle of 138°, a synthetic blood contact angle of 128°, an oil contact angle of 110°, and an ethanol-water solution contact angle of 98°. The sponge-like interconnected micro-nano-scale network of pores in the microporous membrane facilitates the rapid transport of gas and moisture molecules, achieving a permeability of 14.62 mm² / s. -1 The moisture permeability is 9.67 kg / m³. -2 d -1 .

[0088] Example 7

[0089] Step 1: Same as Step 1 in Example 1, except that the fluoropolymer is a fluoroacrylic resin.

[0090] Step 2: Same as step 2 in Example 1.

[0091] Step 3: Same as step 3 in Example 1.

[0092] Step 4: Same as step 4 in Example 1.

[0093] The resulting sponge-like interconnected network structure high-permeability and moisture-permeable protective membrane material exhibits a tensile breaking strength of 56.62 MPa, a water pressure resistance of 12.74 kPa, a water contact angle of 137°, a synthetic blood contact angle of 125°, an oil contact angle of 109°, and an ethanol-water solution contact angle of 95°. The sponge-like interconnected micro-nano-scale network of pores in the microporous membrane facilitates the rapid transport of gas and moisture molecules, achieving a permeability of 14.52 mm² / s. -1 The moisture permeability is 8.66 kg / m³. -2 d -1 .

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make several improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a highly breathable and moisture-permeable protective membrane material with a sponge-like interconnected network structure, characterized in that, Includes the following steps: Step 1: Prepare a casting solution by mixing hygroscopic inorganic salts, polymers, fluoropolymers, and solvents; Step 2: Apply the casting solution to the substrate to form an initial wet film; Step 3: Immerse the initial wet film obtained in Step 2 into a coagulation bath for phase transformation to obtain a microporous membrane with a sponge-like interconnected network structure. Step 4: Mix the hydrophobic finishing agent and nanoparticles to prepare a spraying solution, spray it onto the microporous membrane obtained in step 3, and dry it to obtain the final product; The hygroscopic inorganic salt is selected from at least one of calcium chloride, magnesium chloride, potassium chloride, sodium sulfate, sodium chloride, copper sulfate, calcium oxide, ammonium sulfate, sodium hypochlorite, and sodium hydroxide. The polymer in step 1 is selected from at least one of polyurethane, thermoplastic polyurethane, polyvinylidene fluoride, polyethylene, polyacrylonitrile, polystyrene, polycaprolactone, polyamide 6, polyamide 66, polyimide, and polyethylene terephthalate. The fluoropolymer is selected from at least one of fluorinated polyurethane (FPU), fluorinated polycarbonate (FPC), fluorinated acrylate (FAA) polymer resin, perfluoropolyether (PFPE), fluorinated polyester (FPET), fluorinated polyaryl ether (FPSF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA), trifluorochloroethylene-ethylene copolymer (ECTFE), polytrifluorochloroethylene (PCTFE), perfluorosulfonic acid (PFSA), fluorinated polyimide (FPI), perfluoro-2,2-dimethyl-1,3-dioxolane-tetrafluoroethylene (PDD-TFE) copolymer, trifluorochloroethylene-vinyl ether copolymer (FEVE), perfluoroethylene propylene (FEP), polyfluorinated vinyl (PVF), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV). The coagulation bath is at least one of water, a mixture of water and ethanol, and a mixture of water and DMF. The hydrophobic finishing agent in step 4 is selected from at least one of fluorinated compounds, organosilicon resins, fluorosilicone polymers, fluorocarbon polymers, and Teflon. The nanoparticles are selected from at least one of hydrophobic nano-silica, metal oxides, and metal nanoparticles.

2. The preparation method according to claim 1, characterized in that, The solvent in step 1 is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, tetrahydrofuran, N-methylpyrrolidone, chloroform, methanol, ethanol, isopropanol, deionized water, acetone, dichloromethane, formic acid, acetic acid, dimethyl sulfoxide, diethyl ether, toluene, trichloroacetic acid, and trifluoroacetic acid.

3. The preparation method according to claim 1, characterized in that, In the casting solution obtained in step 1, the polymer content is 8-20% by mass, the mass fraction ratio of polymer to hygroscopic inorganic salt is 9:1-5:5, and the mass content of fluorinated polymer is 1-10% by mass. The viscosity of the casting solution is 1~10 Pa·s.

4. The preparation method according to claim 1, characterized in that, The substrate in step 2 is selected from at least one of woven fabrics, knitted fabrics, nonwoven fabrics, and electrospun fiber membranes; And / or, the thickness of the film formed by scraping in step 2 is 100~2500μm.

5. The preparation method according to claim 1, characterized in that, In step 3, the temperature of the coagulation bath is 20~60℃, and the phase transformation time is 0.5~2h.

6. The preparation method according to claim 1, characterized in that, The mass content of nanoparticles in the spraying liquid in step 4 is 1-15%.

7. The sponge-like interconnected network structure highly breathable and moisture-permeable protective membrane material prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the sponge-like interconnected network structure highly breathable and moisture-permeable protective membrane material as described in claim 7 in the preparation of medical protective equipment.

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