Waterproof and windproof breathable biomimetic membrane and preparation method thereof

Abstract

The application relates to a waterproof and windproof air-permeable bionic membrane and a preparation method thereof, and relates to the technical field of composite functional membranes.The bionic membrane is a three-layer composite membrane, and the specific structure is that a honeycomb porous membrane is used as a base material, and a waterproof and moisture-permeable membrane is compounded on two surfaces of the base material to form the bionic membrane; wherein the honeycomb porous membrane is modified and finished by polyvinyl alcohol-chitosan hydrogel.The bionic membrane provided by the application is designed based on the principle of bionics, the two waterproof and moisture-permeable membranes are used as the outer layers of the membrane to endow the membrane with excellent waterproof and windproof properties, and the honeycomb porous membrane in the middle layer is used as the main body of the membrane to ensure the air permeability of the membrane and endow the membrane with excellent mechanical properties.The bionic membrane provided by the application has strong comprehensive performance, can improve the wearing comfort and functionality of outdoor sports clothes, and has a good application prospect in the field of garment fabrics.

Description

Technical Field

[0001] The invention belongs to the technical field of composite functional membranes, and particularly relates to a waterproof, windproof and breathable bionic membrane and a preparation method thereof. Background Art

[0002] Outdoor sports are easily affected by rain and snow. Clothing soaked in rain easily clings to the body, causing a cold, damp feeling and poor comfort. Therefore, improving the user experience is crucial for improving the thermal and moisture comfort, waterproofness, windproofness, and breathability of clothing fabrics. As consumer demand for apparel textiles shifts from aesthetics and comfort to multifunctional textiles that offer antibacterial, heat-generating, warmth-retaining, and moisture-wicking properties, the textile industry is shifting its research focus from traditional fabric research to functional textiles, aiming to design clothing with enhanced user experience. Currently, functional improvements to apparel fabrics include coating them with functional finishing agents and laminating them with functional membranes.

[0003] Continuing research into biomimetic technology has revealed that some of the remarkable biological properties of amphibians and anurans hold potential for biomimetic applications. This has led to the development of functional textiles, particularly for outdoor sportswear. For example, X-Bionic's Symbionic biomimetic membrane mimics the breathing properties of frog skin, improving breathability and perspiration, while reducing the risk of overheating. Specifically, the skin of amphibians and anurans consists of an epidermis and dermis. The inner layer of the epidermis is the germinal layer, while the outer layer is the stratum corneum, which, to a certain extent, reduces water evaporation. Furthermore, the dermis of anurans contains numerous glands, such as mucous and serous glands. Some frogs have hollow mucous glands. When the skin is dehydrated or in low temperatures, they secrete mucus to absorb water vapor from the environment, thereby maintaining skin water and body temperature balance. Therefore, the histological morphology of amphibian and anuran skin is of great significance for the research and development of high-performance functional biomimetic membranes, which can improve the comfort and functionality of outdoor sportswear and enhance its application in clothing fabrics. Summary of the Invention

[0004] The purpose of the present invention is to provide a waterproof, windproof and breathable bionic membrane and a preparation method thereof in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] As the first aspect of the present invention, the present invention provides a waterproof, windproof and breathable bionic membrane, which is a three-layer composite membrane. The specific structure is formed by using a honeycomb porous membrane as a substrate and compounding waterproof and moisture-permeable membranes on both sides of the substrate; wherein the honeycomb porous membrane is modified and finished by polyvinyl alcohol-chitosan hydrogel.

[0007] As a further optimization solution of the present invention, the honeycomb porous membrane is a polylactic acid honeycomb porous membrane, and its preparation method includes the following steps:

[0008] (1) dissolving a certain amount of polylactic acid in dichloromethane solvent to obtain a casting solution with a concentration of 2-5 wt%;

[0009] (2) at a temperature of 30-35° C. and a relative humidity of 50-80%, casting a film on a substrate, placing the substrate in a sealed space, and adding a saturated aqueous solution of sodium chloride to the sealed space to maintain the humidity of the sealed space at 75-80%, and obtaining a polylactic acid film after the solvent evaporates;

[0010] (3) The polylactic acid film is vacuum dried at 50-55°C for 90-120 minutes to remove the residual solvent.

[0011] As a further optimized solution of the present invention, the waterproof and breathable membrane is a polytetrafluoroethylene waterproof and breathable membrane, a polyvinylidene fluoride waterproof and breathable membrane or a polytetrafluoroethylene-polyvinylidene fluoride waterproof and breathable membrane.

[0012] As a further optimization scheme of the present invention, the preparation method of the waterproof and breathable membrane is to first add at least one of polytetrafluoroethylene or polyvinylidene fluoride to a solvent, stir at 70-90°C for 1-2 hours until completely dissolved, stand and degas to obtain a casting liquid, then scrape the casting liquid onto a substrate, place the substrate in a coagulation bath after pre-volatilization to form a film, rinse in clean water for 12-24 hours, take out the membrane and dry it to obtain it.

[0013] As a further optimized solution of the present invention, the preparation method of the polyvinyl alcohol-chitosan hydrogel comprises the following steps:

[0014] (1) dissolving a certain amount of chitosan in a 0.1 mol / L acetic acid solution to obtain a chitosan solution;

[0015] (2) Add polyvinyl alcohol powder in an amount of half the mass of chitosan to the chitosan solution, stir at 80°C until the polyvinyl alcohol is completely dissolved, cool to room temperature, and stir overnight to form a uniform mixed solution. Add 0.2 mol / L glutaraldehyde solution dropwise to the mixed solution at 25°C, and continue stirring for a cross-linking reaction for 60-120 minutes to obtain a hydrogel solution;

[0016] (3) Under ice bath conditions, phosphoric acid is first added dropwise to the hydrogel solution until the volume percentage of phosphoric acid in the hydrogel solution system is 2-4%. Then, propylene glycol is added dropwise to the hydrogel solution until the volume percentage of propylene glycol in the hydrogel solution system is 2-4%. After stirring for 30-60 minutes, the pH value of the hydrogel solution is adjusted to 7.5.

[0017] As a second aspect of the present invention, the present invention also provides a method for preparing any of the above-mentioned waterproof, windproof and breathable bionic membranes, comprising the following steps:

[0018] (1) placing the honeycomb porous membrane in a polyvinyl alcohol-chitosan hydrogel solution and subjecting it to ultrasonic vibration modification for 60-120 minutes, and drying the honeycomb porous membrane after the modification is completed for later use;

[0019] (2) A waterproof and breathable membrane is prepared, and a polyurethane adhesive is coated on one side of the waterproof and breathable membrane and then composited with the membrane on one side of a honeycomb porous membrane. The other side of the honeycomb porous membrane is composited with the waterproof and breathable membrane in the same manner to obtain a three-layer composite membrane. The three-layer composite membrane is laminated to obtain the biomimetic membrane.

[0020] As a further optimization scheme of the present invention, the power of the ultrasonic oscillation treatment is 50-70kHz, and the method for drying the honeycomb porous membrane is to dry the honeycomb porous membrane with hot air, the hot air temperature is 40-50°C, the wind speed is 2-5m / s, and the drying time is 60-120min.

[0021] The beneficial effects of the present invention are:

[0022] The biomimetic membrane provided by the present invention is designed based on the principles of bionics. Its specific structure is a three-layer composite membrane structure, which is made of a honeycomb porous membrane modified and finished with polyvinyl alcohol-chitosan hydrogel as a base material, and a waterproof and breathable membrane composited on both sides of the base material. On the one hand, the waterproof and breathable membrane as the outer layer of the biomimetic membrane can give the membrane excellent waterproof and windproof properties, while the honeycomb porous membrane in the middle layer, as the main body of the membrane, can ensure the membrane's air permeability while also giving it excellent mechanical properties. On the other hand, after the honeycomb porous membrane of the biomimetic membrane is modified and finished with polyvinyl alcohol-chitosan hydrogel, the biomimetic membrane can be composited with the fabric to further improve the fabric's moisture absorption and heat generation performance.

[0023] The bionic membrane provided by the present invention has strong comprehensive performance, can improve the wearing comfort and functionality of outdoor sportswear, and has good application prospects in the field of clothing fabrics. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of the waterproof, windproof and breathable bionic membrane provided by the present invention. DETAILED DESCRIPTION

[0025] The present application is described in further detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0026] 1. Materials and Methods

[0027] Unless otherwise specified, all other materials and reagents used in this example can be obtained through commercial channels.

[0028] 1. Preparation of waterproof, windproof and breathable bionic membrane

[0029] 1.1 Preparation of honeycomb porous membrane

[0030] The honeycomb porous membrane is specifically a polylactic acid honeycomb porous membrane. The preparation method of the polylactic acid honeycomb porous membrane is as follows: polylactic acid is dissolved in a dichloromethane solvent to obtain a casting solution with a concentration of 2-5wt%. In this embodiment, the concentration of the casting solution is preferably 4wt%. Then, at a temperature of 30-35°C and a relative humidity of 50-80%, the casting solution is dropwise cast on a substrate to form a film. In this embodiment, the temperature is preferably 35°C and the relative humidity is 60%. The substrate is placed in a sealed space, and a saturated aqueous solution of sodium chloride is added to the sealed space to maintain the humidity in the sealed space at 75-80%. In this embodiment, the humidity is preferably 75%. After the solvent evaporates, a polylactic acid membrane is obtained. The polylactic acid membrane is vacuum-dried at a temperature of 50-55°C for 90 minutes to remove the residual solvent. The drying temperature in this embodiment is preferably 50°C. The thickness of the honeycomb porous membrane is about 50μm.

[0031] 1.2 Preparation of waterproof and breathable membrane

[0032] The waterproof and breathable membrane is a polytetrafluoroethylene waterproof and breathable membrane, a polyvinylidene fluoride waterproof and breathable membrane or a polytetrafluoroethylene-polyvinylidene fluoride waterproof and breathable membrane. In this embodiment, polyvinylidene fluoride waterproof and breathable membrane is taken as an example. First, polyvinylidene fluoride is added to a solvent, stirred at 90°C for 2 hours until completely dissolved, and allowed to stand for degassing to obtain a casting liquid. The solvent is N, N-dimethylformamide. In this embodiment, the casting liquid is preferably 5wt%. Then, the casting liquid is scraped onto the substrate. After pre-volatilization, the substrate is placed in a coagulation bath to form a film, rinsed in clean water for 12 hours, and the film is taken out and dried to obtain a waterproof and breathable membrane. The thickness of the waterproof and breathable membrane is about 120μm.

[0033] 1.3. Modification and finishing of honeycomb porous membrane

[0034] (1) Preparation of polyvinyl alcohol-chitosan hydrogel

[0035] Chitosan was first dissolved in 0.1 mol / L acetic acid solution to obtain a chitosan solution. The mass volume ratio of chitosan to acetic acid solution was 4:1 (g:L). Polyvinyl alcohol powder (PVA) in an amount half the mass of chitosan was then added to the chitosan solution. The mixture was then stirred at 80°C until the PVA was completely dissolved. The mixture was then cooled to room temperature and stirred overnight to form a uniform mixed solution. Finally, 0.2 mol / L glutaraldehyde solution was added dropwise to the mixed solution at 25°C. The cross-linking reaction was continued with stirring for 120 minutes to obtain a hydrogel solution.

[0036] Under ice bath conditions, phosphoric acid is first added dropwise to the hydrogel solution until the volume percentage of phosphoric acid in the hydrogel solution system is 2-4%, preferably 2% in this embodiment. Then, glycerol is added dropwise to the hydrogel solution until the volume percentage of glycerol in the hydrogel solution system is 2-4%, preferably 4% in this embodiment. After stirring for 30-60 minutes, the pH value of the hydrogel solution is adjusted to 7.5.

[0037] (3) Modification and finishing

[0038] The honeycomb porous membrane is placed in a polyvinyl alcohol-chitosan hydrogel solution and subjected to ultrasonic oscillation modification for 120 minutes. After the modification is completed, the honeycomb porous membrane is dried. The power of the ultrasonic oscillation treatment can be selected to be 50-70kHz. In this embodiment, 60kHz is preferred. The method for drying the honeycomb porous membrane is as follows: the honeycomb porous membrane is hot air dried, the hot air temperature is 40-50°C, the wind speed is 2-5m / s, and the drying time is 60-120min. In this embodiment, the preferred hot air temperature is 45°C, the wind speed is 4m / s, and the drying time is 60min.

[0039] 1.4 Preparation of biomimetic membrane

[0040] After coating one side of the waterproof and breathable membrane with a polyurethane adhesive, it is composited with one side of the honeycomb porous membrane obtained by the modification and finishing in step 1.3. Then, the other side of the honeycomb porous membrane is composited with the waterproof and breathable membrane according to the same operation to obtain a three-layer composite membrane. The three-layer composite membrane is laminated to obtain the bionic membrane. The polyurethane adhesive is sprayed on the surface of the waterproof and breathable membrane. The thickness of the finally obtained bionic membrane does not exceed 350 μm. The specific implementation method of using a polyurethane adhesive to composite the honeycomb porous membrane between two waterproof and breathable membranes is a method for preparing a composite membrane known in the art. The present invention does not improve this method, so it will not be described in detail.

[0041] The schematic diagram of the structure of the biomimetic membrane prepared in steps 1.1-1.4 is as follows Figure 1 As shown, Figure 1The circled part is a schematic diagram of the structure of the enlarged honeycomb porous membrane. It can be seen that the pore structure of the honeycomb porous membrane is uniform in honeycomb shape, the pore sizes are uniform and arranged regularly, and after modification and finishing, the polyvinyl alcohol-chitosan hydrogel is attached to the pore structure of the honeycomb porous membrane.

[0042] 2. Verification test

[0043] In order to verify the influence of the structural composition of the biomimetic membrane on its performance, the biomimetic membrane prepared by steps 1.1-1.4 was counted as membrane sample A.

[0044] Then, the structural composition of the biomimetic membrane is designed as follows:

[0045] Membrane sample B: The difference from membrane sample A is that the polylactic acid fiber membrane prepared by electrospinning method is used instead of the honeycomb porous membrane.

[0046] The specific preparation method of polylactic acid fiber membrane is as follows: polylactic acid is dissolved in dichloromethane solvent to obtain a spinning solution with a concentration of 4wt%, and more than 3mL of spinning solution is absorbed with a 10mL syringe. The syringe is fixed to the propulsion pump of the electrospinning machine, and the distance between the needle and the receiving plate is adjusted to 16cm. The voltage of the high-voltage power supply is adjusted to 16kV, the spinning rate is 0.5mL / h, the spinning volume is 3mL, and the ambient temperature is 25°C. After the spraying is completed, the spinning membrane is heat treated at 50°C for 4h.

[0047] Film sample C: The difference from film sample A is that no modification or finishing of the polyvinyl alcohol-chitosan hydrogel is performed.

[0048] Membrane sample D: The difference from membrane sample A is that the preparation method of the polyvinyl alcohol-chitosan hydrogel used is different. Specifically, the preparation method of the polyvinyl alcohol-chitosan hydrogel used in membrane sample D is: first dissolve chitosan in an acetic acid solution with a concentration of 0.1 mol / L to obtain a chitosan solution, and the mass volume ratio of chitosan to acetic acid solution is 4:1 (g:L), and then add polyvinyl alcohol powder in an amount of half the mass of chitosan to the chitosan solution, and then stir at 80°C until the polyvinyl alcohol is completely dissolved, cool to room temperature, and stir overnight to form a uniform mixed solution, and finally add glutaraldehyde solution with a concentration of 0.2 mol / L dropwise to the mixed solution at 25°C, and continue stirring for 120 minutes to obtain a hydrogel solution.

[0049] Membrane sample E: The difference from membrane sample A is that the preparation method of the polyvinyl alcohol-chitosan hydrogel used is different. Specifically, the preparation method of the polyvinyl alcohol-chitosan hydrogel used in membrane sample E is as follows: first, chitosan is dissolved in an acetic acid solution with a concentration of 0.1 mol / L to obtain a chitosan solution, and the mass volume ratio of chitosan to acetic acid solution is 4:1 (g:L); then, polyvinyl alcohol powder in an amount of half the mass of chitosan is added to the chitosan solution; then, the mixture is stirred at 80°C until the polyvinyl alcohol is completely dissolved, cooled to room temperature, and stirred overnight to form a uniform mixed solution; finally, a glutaraldehyde solution with a concentration of 0.2 mol / L is added dropwise to the mixed solution at 25°C, and the cross-linking reaction is stirred continuously for 120 minutes to obtain a hydrogel solution;

[0050] Under ice bath conditions, glycerophosphoric acid is first added dropwise to the hydrogel solution until the glycerophosphoric acid content in the hydrogel solution system is 2%, stirred for 30-60 minutes, and then the pH value of the hydrogel solution is adjusted to 7.5.

[0051] Membrane sample F: The difference from membrane sample A is that during the modification and finishing of the honeycomb porous membrane, the honeycomb porous membrane is placed in a polyvinyl alcohol-chitosan hydrogel solution for immersion treatment and modification for 120 minutes. After the modification is completed, the honeycomb porous membrane is dried. The drying method for the honeycomb porous membrane is consistent with the drying method for membrane sample A.

[0052] Control membrane sample: The difference from membrane sample A is that it does not contain the honeycomb porous membrane modified with polyvinyl alcohol-chitosan hydrogel. Only one side of one waterproof and breathable membrane is coated with polyurethane adhesive and then composited onto another waterproof and breathable membrane.

[0053] 2.1 Waterproof performance test

[0054] (1) Hydrostatic pressure test

[0055] Film samples AF and a control were subjected to a hydrostatic pressure test in accordance with GB / T 4744-2013. The test method was as follows: Wipe the test water from the surface of the clamped sample and clamp the sample so that the front of the sample is in contact with the water. A continuously increasing water pressure was applied to the sample at a rate of 60 cm H₂O / min, and water seepage was observed. During the pressure increase, the pressure was stopped just as the third water droplet appeared on the sample. The hydrostatic pressure at this point was recorded. Five replicates were performed for each film sample, and the results were averaged.

[0056] (2) Water resistance test

[0057] Testing was conducted according to the test method specified in GB / T4745-2012, "Testing and Evaluation of Water Resistance of Textiles—Water Immersion Method." Five replicates were performed for each film sample, and the results were averaged. Water resistance is graded as follows: Levels 2-3: Poor water resistance; Level 3: Fair water resistance; Levels 3-4: Good water resistance; Level 4: Very good water resistance; and Levels 4-5 and 5: Excellent water resistance.

[0058] The results are shown in Table 1.

[0059] Table 1. Statistics of waterproof performance test results of membrane samples

[0060]

[0061]

[0062] As shown in Table 1, membrane samples AF all feature a three-layer composite structure, with the outermost layer being a polyvinylidene fluoride waterproof and breathable membrane. The pores on the surface of the polyvinylidene fluoride waterproof and breathable membrane exhibit a network-like, microporous structure. Its waterproof and breathable properties are based on the fact that the pore size of the membrane is smaller than a raindrop but larger than a water vapor molecule, preventing water droplets from passing through, resulting in water repellency. Therefore, membrane samples AF all exhibit excellent anti-wetting properties, achieving a water repellency rating of 4-5. The control membrane, constructed from two layers of polyvinylidene fluoride waterproof and breathable membrane, also exhibits excellent anti-wetting properties due to the waterproof properties of the polyvinylidene fluoride waterproof and breathable membrane.

[0063] Table 1 also shows a difference in hydrostatic pressure resistance between film samples AF and the control. Film sample AF has a higher hydrostatic pressure resistance than the control. This is because film sample AF is a three-layer composite membrane, while the control is a two-layer composite membrane. Film samples B and F have slightly higher hydrostatic pressure resistance than the other films. Film sample B's middle layer is a polylactic acid fiber membrane produced by electrospinning. While the middle layer of film sample F is a honeycomb porous membrane, it was not subjected to ultrasonic vibration during modification and finishing. Therefore, it is speculated that the change in the structural density of the film's middle layer accounts for the slightly higher hydrostatic pressure resistance of films B and F compared to the other films.

[0064] 2.2. Air permeability test

[0065] The air permeability of the membrane samples was characterized by water vapor transmission rate. The water vapor transmission rates of membrane samples AF and the control membrane were tested according to ISO 2528-1995, "Sheet materials - Determination of water vapor transmission rate by gravimetric method." The results are shown in Table 2.

[0066] Table 2. Statistics of air permeability test results of membrane samples

[0067]

[0068]

[0069] As can be seen from Table 2, the water vapor permeability of film sample AF is lower than that of the control film sample. The reason is that film sample AF is a three-layer composite membrane, while the control film sample is a two-layer composite membrane. The air permeability of the two-layer composite membrane is better than that of the three-layer composite membrane. Compared with film samples AF, the water vapor permeability of film sample A is less reduced than that of the control film sample. It can be seen that the honeycomb porous membrane has a smaller impact on the overall air permeability of the film sample. The water vapor permeability of film sample B is more reduced than that of film sample A. It can be seen that the polylactic acid fiber membrane prepared by electrospinning has an adverse effect on the air permeability of the membrane sample and is not as good as the polylactic acid honeycomb porous membrane. In addition, although the middle layer of film sample F is a honeycomb porous membrane, it was not subjected to ultrasonic vibration treatment during modification and finishing, which would damage the pore structure of the membrane sample. It can also be seen from the table that its water vapor permeability is reduced to a certain extent compared with film sample A.

[0070] 2.3 Mechanical properties test

[0071] Film samples AF and the control film were made into standard dumbbell strips according to GB / T1040.3-2006. The tensile strength (transverse tensile strength and longitudinal tensile strength) and elongation at break of the film samples were measured at a speed of 100 mm / min. The results are shown in Table 3.

[0072] Table 3. Statistics of mechanical properties test results of membrane samples

[0073]

[0074] The results in Table 3 show that compared to the control film, the tensile strength and elongation at break of film samples AF are somewhat improved. This is due to the inclusion of an intermediate layer, which makes the film more resistant to stretching and improves its mechanical properties. Compared to film sample A, film sample C exhibits a decrease in tensile strength and elongation at break. This indicates that the modification of the honeycomb porous membrane with polyvinyl alcohol-chitosan hydrogel has a positive effect on improving the overall mechanical properties of the film. The tensile strength and elongation at break of film sample A are slightly lower than those of films B and F, but the differences are not significant.

[0075] 2.4 Application Test

[0076] The film sample AF and the control film sample were laminated on one side of the polyester fabric to prepare the laminated fabric AF and the control laminated fabric, and the moisture absorption and heat generation performance of the laminated fabric was tested.

[0077] The test equipment uses an electric constant temperature blower drying oven, a constant temperature and humidity chamber, and a temperature sensor. Referring to the standard GB / T29866-2013 "Test method for moisture absorption and heat generation performance of textiles", 6 fabric samples are cut from each type of coated fabric, and the reverse sides of any two of the fabric samples are pasted together. Polyester thread is used to use a flat seam method to sew the three sides of the samples with the reverse sides pasted together to form a bagged sample. During the test, the temperature sensor is placed inside the bagged sample.

[0078] Place the bagged sample to be used in the test in an electric constant temperature blast drying oven and dry it for 2 hours. After drying, place it in a drying dish containing anhydrous calcium chloride, ensure that the drying dish is vacuum sealed, and place it in a 20℃ environment for 2 hours. Then place it in a constant temperature and humidity box at 20℃ and 90% humidity. Use a temperature sensor to measure the sample, and measure it every 15s for 1 hour. During the measurement process, the temperature fluctuation in the box should be minimized to avoid affecting the test. After the test, the maximum temperature rise value and average temperature rise value of each group of coated fabrics within 30 minutes are calculated by comparing it with the temperature of the blank test group and subtracting the temperature measurement value of the blank test group.

[0079] The results are shown in Table 4.

[0080] Table 4. Statistics of moisture absorption and heat generation performance test results of coated fabrics

[0081]

[0082] As can be seen from Table 4, the hygroscopic and heat-generating properties of coated fabrics AF are generally better than those of the control coated fabric. It can be seen that the structure of the membrane used in the coated fabric has a certain degree of influence on the hygroscopic and heat-generating properties of the fabric itself. Comparison of coated fabrics A and C shows that hydrogel modification and finishing of the honeycomb porous membrane of the membrane-like intermediate layer has a positive effect on improving the hygroscopic and heat-generating properties of the fabric. At the same time, comparison of coated fabrics DE shows that the preparation method of polyvinyl alcohol-chitosan hydrogel has a certain correlation with its improvement in the hygroscopic and heat-generating properties of the fabric. The biomimetic membrane provided by the present invention, after being composited with the fabric, has an effect on improving the hygroscopic and heat-generating properties of the fabric, which can provide the fabric with a better user experience. The fabric can be used to prepare sportswear to improve wearing comfort.

[0083] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A waterproof, windproof and breathable bionic membrane, characterized by: The biomimetic membrane is a three-layer composite membrane, specifically a honeycomb porous membrane as a base material, formed by compounding waterproof and breathable membranes on both sides of the base material; wherein the honeycomb porous membrane is modified and finished with polyvinyl alcohol-chitosan hydrogel; The honeycomb porous membrane is a polylactic acid honeycomb porous membrane, and its preparation method comprises the following steps: (1) dissolving a certain amount of polylactic acid in dichloromethane solvent to obtain a casting solution with a concentration of 2-5 wt%; (2) At a temperature of 30-35°C and a relative humidity of 50-80%, a film is cast on a substrate by dropping a film-casting liquid droplet, and then the substrate is placed in a sealed space. A saturated aqueous solution of sodium chloride is added to the sealed space to maintain the humidity in the sealed space at 75-80%. After the solvent evaporates, a polylactic acid film is obtained; (3) Dry the polylactic acid film in a vacuum at 50-55°C for 90-120 minutes to remove the residual solvent; The preparation method of the polyvinyl alcohol-chitosan hydrogel is specifically as follows: (1) Dissolve a certain amount of chitosan in 0.1 mol / L acetic acid solution to obtain a chitosan solution; (2) Add polyvinyl alcohol powder in an amount of half the mass of chitosan to the chitosan solution, stir at 80°C until the polyvinyl alcohol is completely dissolved, cool to room temperature, and stir overnight to form a uniform mixed solution. Add 0.2 mol / L glutaraldehyde solution dropwise to the mixed solution at 25°C, and continue stirring for a cross-linking reaction for 60-120 minutes to obtain a hydrogel solution; (3) Under ice bath conditions, add phosphoric acid dropwise to the hydrogel solution until the volume percentage of phosphoric acid in the hydrogel solution system is 2-4%. Then, add propylene glycol dropwise to the hydrogel solution until the volume percentage of propylene glycol in the hydrogel solution system is 2-4%. Stir for 30-60 minutes and then adjust the pH value of the hydrogel solution to 7.

5.

2. The waterproof, windproof and breathable bionic membrane according to claim 1, characterized in that: The waterproof and breathable membrane is a polytetrafluoroethylene waterproof and breathable membrane, a polyvinylidene fluoride waterproof and breathable membrane or a polytetrafluoroethylene-polyvinylidene fluoride waterproof and breathable membrane.

3. The waterproof, windproof and breathable bionic membrane according to claim 1, characterized in that: The preparation method of the waterproof and breathable membrane comprises the following steps: firstly adding at least one of polytetrafluoroethylene or polyvinylidene fluoride into a solvent, stirring at 70-90° C. for 1-2 hours until completely dissolved, standing for degassing to obtain a casting liquid, then scraping the casting liquid onto a substrate, placing the substrate into a coagulation bath after pre-volatilization to form a membrane, rinsing in clean water for 12-24 hours, taking out the membrane and drying it to obtain the membrane.

4. A method for preparing the waterproof, windproof and breathable bionic membrane according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) placing the honeycomb porous membrane in a polyvinyl alcohol-chitosan hydrogel solution and subjecting it to ultrasonic vibration modification for 60-120 minutes. After the modification is completed, the honeycomb porous membrane is dried and set aside; (2) A waterproof and breathable membrane is prepared, and a polyurethane adhesive is coated on one side of the waterproof and breathable membrane and then composited with the membrane on one side of a honeycomb porous membrane. The other side of the honeycomb porous membrane is composited with the waterproof and breathable membrane according to the same operation to obtain a three-layer composite membrane. The three-layer composite membrane is laminated to obtain the biomimetic membrane.

5. The method for preparing a waterproof, windproof and breathable bionic membrane according to claim 4, characterized in that: In step (1), the power of the ultrasonic oscillation treatment is 50-70kHz, and the method for drying the honeycomb porous membrane is to dry the honeycomb porous membrane with hot air, the hot air temperature is 40-50°C, the wind speed is 2-5m / s, and the drying time is 60-120min.

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