Composite functional waterproof breathable film as well as preparation method and application thereof

Abstract

The invention belongs to the field of polyester films, and particularly relates to a composite functional waterproof breathable film as well as a preparation method and application thereof. Comprising the following steps: preparing a composite organic spinning solution; preparing an antibacterial waterproof surface layer membrane material; preparing a moisture-absorbing and breathable core layer membrane material; and compounding the membrane material. 2-carene, dragon's blood powder and a white wax purified substance are added into a PET spinning solution, in the subsequent spinning process, the white wax purified substance with long-chain lipid as the main component forms an orderly-arranged hydrophobic layer through molecular self-assembly, a low-surface-energy substrate is formed, 2-carene and white wax ester form an overlapped molecular network, the contact angle of the 2-carene and the white wax ester is increased, and the surface energy of the substrate is increased. Rich loureirin B in the dragon's blood and a white wax purified product / carene system form a hydrogen bond interlocking structure, the surface free energy is further reduced, the prepared antibacterial and waterproof surface layer membrane material not only has ultrahigh hydrophobicity, but also has good antibacterial performance, and the antibacterial and waterproof performance of a subsequent waterproof and breathable membrane is improved.

Description

Technical Field

[0001] The present invention belongs to the field of polyester films, and particularly relates to a composite functional waterproof and breathable film, a preparation method thereof, and an application thereof. Background Art

[0002] At present, the waterproof and breathable components of consumer electronics (such as smart phones and smart watches) and precision components (industrial sensors and automotive electronics) mainly rely on polytetrafluoroethylene (EPTFE) films.

[0003] In China, the PTFE film mostly adopts a stepwise longitudinal / transverse stretching process, which is difficult to achieve precise regulation of nano-scale pores. Moreover, the stretching preparation process of the PTFE film makes it difficult to add antibacterial components to the raw materials, easily resulting in uneven pore distribution during the stretching process of the PTFE film, affecting the performance of the film material. And its ultra-low surface energy also makes the adhesion of the antibacterial coating poor. The domestic waterproof and breathable film industry is restricted by three major bottlenecks: low raw material purity, poor equipment accuracy, and weak process controllability, resulting in products remaining in the mid- to low-end market for a long time. Therefore, there is an urgent need to develop a composite film with high waterproofness, high breathability, and antibacterial properties. Summary of the Invention

[0004] In order to solve the above technical defects, the present invention has developed a preparation method of a composite functional waterproof and breathable film. The prepared composite functional waterproof and breathable film has excellent waterproof and breathable properties and good antibacterial properties.

[0005] The technical solution of the present invention is as follows: A preparation method of a composite functional waterproof and breathable film, comprising the following steps: S1: Preparation of a composite organic spinning solution Purify and extract the secretion of the Chinese wax insect to obtain a purified Chinese wax. Mix acetone and hexafluoroisopropanol and add them to polyethylene terephthalate for dissolution to obtain a PET spinning solution. Ultrasonically disperse 2-carene and dragon's blood powder in acetone to obtain a composite suspension. Add the purified Chinese wax and a surfactant to the PET spinning solution, and then add the composite suspension for ultrasonic dispersion to obtain a composite organic spinning solution; S2: Preparation of an antibacterial and waterproof surface layer film material Add tetrabutylammonium bromide to the composite organic spinning solution to adjust the conductivity to obtain a pre-spinning solution. Prepare a nano-cellulose suspension from nano-cellulose and deionized water. Then dissolve cetyltrimethoxysilane in an ethanol aqueous solution, adjust the pH and stir to obtain an HDTMS solution. Add the nano-cellulose suspension to the HDTMS solution and stir to obtain a spray solution. Spin the pre-spinning solution through a pulsed power supply to obtain a layer of spun film, and then spray the spray solution on the surface. After drying, obtain an antibacterial and waterproof surface layer film material; S3: Preparation of a moisture-absorbing and breathable core layer film material and lamination of the film materials Sodium alginate and hexadecyl glycidyl ether are placed in a dimethyl sulfoxide / deionized water mixed solvent, and heated and reacted in a nitrogen atmosphere. Then, phenylboronic acid and hydrogen peroxide are added, and the reaction is continued by heating. After dialysis, modified sodium alginate is obtained. The modified sodium alginate, polyethylene terephthalate, and heat stabilizer are melt-blended and extruded. After the extruded melt is cooled, it is stretched to obtain a moisture-absorbing and breathable core layer film material. A sandwich structure of antibacterial and waterproof surface layer film material - moisture-absorbing and breathable core layer film material - antibacterial and waterproof surface layer film material is placed in a mold for molding, and cooled to obtain a composite functional waterproof and breathable film.

[0006] Furthermore, the preparation of the composite organic spinning solution in step S1 includes the following steps: S1.1: The secretion of Ericerus pela is added to an ethanol solution with a concentration of 70 - 75% according to a solid-liquid ratio of 1:(10 - 12) g / mL, and shaken in a water bath at 45 - 50 °C and 120 - 150 rpm for 1.5 - 2 hours. Then, it is filtered through a 400 - 500 mesh sieve to obtain a crude filtrate. The crude filtrate and an ethanol solution with a concentration of 95 - 97% are mixed evenly at a volume ratio of 1:(3 - 4), left to stand overnight at 3 - 4 °C, and then centrifuged at a speed of 4000 - 5000 rpm for 10 - 12 minutes. After collecting the supernatant, deionized water is added and stirred until a large amount of precipitate precipitates. After centrifuging at a speed of 4000 - 5000 rpm for 10 - 12 minutes, the precipitate is retained and vacuum dried at 40 - 45 °C to obtain purified Ericerus pela wax; S1.2: Acetone and hexafluoroisopropanol are mixed in a volume ratio of (3 - 4):(7 - 10) and placed in a container, and magnetically stirred for 30 - 35 minutes to obtain a mixed solvent. Then, 25 - 30 wt% of polyethylene terephthalate is added, and stirred in a constant temperature water bath at 60 - 65 °C for 2 - 3 hours until completely dissolved to obtain a PET spinning solution; S1.3: 2-Carene and dragon's blood powder are ultrasonically dispersed in acetone according to a mass ratio of 1:(4 - 5), with an ultrasonic frequency of 25 - 30 kHz and an ultrasonic time of 8 - 10 minutes to obtain a composite suspension with a dragon's blood powder concentration of 2 - 3%. Take the PET spinning solution and place it in a container. First, add 1 - 1.2 wt% of purified Ericerus pela wax and 0.1 - 0.2 wt% of surfactant, and then add 20 - 25% of the volume of the composite suspension of the PET spinning solution, and ultrasonically disperse it at a frequency of 30 - 35 kHz for 10 - 15 minutes to obtain a composite organic spinning solution.

[0007] Furthermore, the preparation of the antibacterial and waterproof surface layer film material in step S2 includes the following steps: S2.1: Use a conductivity meter to measure the conductivity of the composite organic spinning solution in real time. After adding 0.03 - 0.05 wt% of tetrabutylammonium bromide each time, stir evenly, and then observe the conductivity measured by the conductivity meter until the conductivity reaches 5.8 - 6 μS / cm to obtain the pre-spinning solution; S2.2: Mix nanocellulose and deionized water and perform ultrasonic dispersion for 25 - 30 minutes to obtain a nanocellulose suspension with a concentration of 3 - 5%. Dissolve cetyltrimethoxysilane in an ethanol aqueous solution with a concentration of 95 - 96%, add acetic acid to adjust the pH to 3 - 4, and stir for 30 - 40 minutes to obtain an HDTMS solution with a concentration of 12 - 15%. Slowly add the nanocellulose suspension to the HDTMS solution at a volume ratio of 1:(1 - 2), and stir at 55 - 60 °C for 8 - 10 hours to obtain a spray solution; S2.3: Add the pre-spinning solution to the syringe of the electrospinning machine. Set the distance between the syringe needle and the aluminum foil drum collector to 12 - 15 cm. Connect the positive pole of the pulsed power supply to the syringe needle and the negative pole to the aluminum foil receiving plate. Perform electrospinning under the conditions of 23 - 27 °C and 25 - 30% RH humidity. Set the syringe propulsion rate to 2 - 3 mL / h and the lateral movement speed to 2 - 2.5 cm / s. The pulsed power supply first spins at a voltage of 18 - 20 kV for 2 - 3 seconds, and then spins at a voltage of 26 - 28 kV for 0.5 - 0.6 seconds until a layer of spinning film covers the aluminum foil receiving plate. Then use an electrostatic sprayer to evenly spray the spray solution on the surface of the spinning film. After peeling off, place it in a vacuum dryer at 60 - 65 °C for 2 - 2.5 hours to obtain the antibacterial and waterproof surface layer film material.

[0008] Further, the preparation of the moisture-absorbing and breathable core layer film material and the lamination of the film materials include the following steps: S3.1: Place sodium alginate and hexadecyl glycidyl ether in a container at a molar ratio of 1:(0.25 - 0.3), add 8 - 10 times the mass of a dimethyl sulfoxide / deionized water mixed solvent, where the volume ratio of dimethyl sulfoxide to deionized water is 1:(0.3 - 0.4), and then add 0.3 - 0.5 wt% of tetrabutylammonium bromide. Heat to 85 - 90 °C under nitrogen protection and react for 4 - 5 hours. Then add 4 - 5 wt% of phenylboronic acid and 0.1 - 0.2 wt% of hydrogen peroxide, continue to heat to 80 - 85 °C under nitrogen protection and react for 3 - 4 hours. Then inject it into a dialysis bag with a molecular weight cut-off of 3200 - 3500 Da and dialyze in flowing deionized water for 72 - 75 hours, and freeze-dry to obtain modified sodium alginate; S3.2: Mix the modified sodium alginate and polyethylene terephthalate with a viscosity of 0.8 - 0.85 dL / g in a mass ratio of 1:(8 - 10), add 0.4 - 0.6 wt% of heat stabilizer and 0.6 - 0.8 wt% of silane coupling agent KH-550, mix evenly, then place it in a twin-screw extruder. Set the temperature of zone I at 240 - 245 °C, the temperature of zone II at 250 - 260 °C, and the temperature of zone III at 265 - 270 °C. Extrude the melt and cool it. When it is cooled to 100 - 105 °C, maintain the temperature and conduct longitudinal and transverse stretching until a film with a thickness of 100 - 200 μm is formed to obtain the moisture-absorbing and breathable core layer film material; S3.3: Heat the moisture-absorbing and breathable core layer film material to 140 - 150 °C, place it in a mold in a sandwich structure of antibacterial and waterproof surface layer film material - moisture-absorbing and breathable core layer film material - antibacterial and waterproof surface layer film material, and then use a molding press for pressing. The molding temperature is 60 - 70 °C, and the molding pressure is 4 - 6 MPa. After cooling, obtain the composite functional waterproof and breathable film.

[0009] Further, in step S1.2, the molecular weight of polyethylene terephthalate is 25,000 - 28,000.

[0010] Further, the surfactant in step S1.3 is fluorocarbon surfactant Capstone FS-3100.

[0011] Further, in step S2.3, the spray voltage of the electrostatic sprayer is 10 - 12 kV, the flow rate is 0.6 - 0.8 mL / h, and the spray amount is 1 - 2 mg / cm 2 。

[0012] Further, the heat stabilizer in step S3.2 is methyltin isooctyl mercaptoacetate.

[0013] A composite functional waterproof and breathable film is prepared by the preparation method of the above-mentioned composite functional waterproof and breathable film.

[0014] On the other hand of the present application, a method for applying the above-mentioned composite functional waterproof and breathable film is provided. By attaching the composite functional waterproof and breathable film to the outer shells of mobile phones, stereos, laptop computers and other electronic devices, it can achieve the effects of waterproofing, breathability and antibacterial.

[0015] The working principle and beneficial effects of the present invention are: 1. In the present invention, the secretion of Ericerus pela is purified and extracted to obtain a purified white wax. Then, 2-carene and dragon's blood powder are ultrasonically dispersed in acetone and added to a PET spinning solution, and then the purified white wax is added for ultrasonic dispersion to obtain a composite organic spinning solution. During the subsequent spinning process, the purified white wax mainly composed of long-chain lipids forms an orderly arranged hydrophobic layer through molecular self-assembly. Its long alkyl chains are bonded to the PET molecular chains through van der Waals forces to form a low surface energy substrate. 2-carene forms an overlapping molecular network with wax esters, and the micro-nano hierarchical structure on the surface of the antibacterial and waterproof surface film material is induced to generate through the steric hindrance effect of terpenes, improving its contact angle. The dracorhodin B rich in dragon's blood forms a hydrogen bond interlocking structure with the purified white wax / carene system, further reducing the surface free energy and enhancing the mechanical stability. Moreover, the terpene structure of 2-carene and the cochinchinenin of dragon's blood can synergistically enhance the antibacterial ability of the film material. The prepared antibacterial and waterproof surface film material not only has ultra-high hydrophobicity but also has good antibacterial properties, improving the antibacterial and waterproof properties of the subsequent waterproof and breathable membrane.

[0016] 2. In the present invention, during the spinning process, a pulsed voltage is used to spin at a voltage of 18 - 20 kV for 2 - 3 seconds first, and then spin at a voltage of 26 - 28 kV for 0.5 - 0.6 seconds. The continuous fibers formed by the basic voltage of 18 - 20 kV constitute a parallel arranged framework, simulating the main vein structure of cicada wings. Then, the periodic bead-like nodes generated by the high-voltage pulse of 26 - 28 kV form cicada wing-like ridge-like protrusions on the fiber surface, effectively improving the roughness and contact angle of the antibacterial and waterproof surface film material. Then, the hydrophobicity is improved by modifying nano-cellulose with hexadecyltrimethoxysilane, and nano-protrusions are formed on the spinning film surface by spraying to further increase the surface roughness, forming a lotus leaf-like papilla structure, further improving the waterproof performance of the subsequent waterproof and breathable membrane.

[0017] 3. In the present invention, sodium alginate is modified by glycidyl hexadecyl ether and phenylboronic acid in sequence, which can not only improve the high-temperature resistance of sodium alginate but also inhibit the swelling caused by the moisture absorption of sodium alginate. The obtained modified sodium alginate and PET form microphase separation during twin-screw extrusion to form through channels, obtaining a moisture-absorbing and breathable core layer film material, which can enhance the moisture-absorbing and breathable ability of the waterproof and breathable membrane. Description of the Drawings

[0018] Figure 1 It is a flow chart of the preparation method of the composite functional waterproof and breathable membrane adopted in the embodiment of the present invention. Detailed Embodiments

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] Example 1 A preparation method of a composite functional waterproof and breathable film is as Figure 1 shown, and includes the following steps: S1: Preparation of a composite organic spinning solution S1.1: Add the secretion of Chinese wax scale insects into an ethanol solution with a concentration of 70% according to a material-liquid ratio of 1:10 g / mL, perform water bath oscillation at 45°C and 120 rpm for 1.5 hours, then pass through a 400-mesh sieve to obtain a crude filtrate. Mix the crude filtrate and an ethanol solution with a concentration of 95% evenly at a volume ratio of 1:3, let it stand overnight at 3°C, then centrifuge at a speed of 4000 rpm for 10 minutes. After collecting the supernatant, add deionized water and stir until a large amount of precipitate precipitates. After centrifuging at a speed of 4000 rpm for 10 minutes, retain the precipitate and perform vacuum drying at 40°C to obtain a purified Chinese wax; S1.2: Mix acetone and hexafluoroisopropanol in a volume ratio of 3:7 and place them in a container, magnetically stir for 30 minutes to obtain a mixed solvent, then add 25 wt% of polyethylene terephthalate with a molecular weight of 25000, and stir at a constant temperature water bath of 60°C for 2 hours until completely dissolved to obtain a PET spinning solution; S1.3: Ultrasonically disperse 2-carene and dragon's blood powder in acetone according to a mass ratio of 1:4, with an ultrasonic frequency of 25 kHz and an ultrasonic time of 8 minutes to obtain a composite suspension with a dragon's blood powder concentration of 2%. Take the PET spinning solution and place it in a container. First, add 1 wt% of the purified Chinese wax and 0.1 wt% of the fluorocarbon surfactant Capstone FS-3100, then add 20% of the volume of the composite suspension of the PET spinning solution, and ultrasonically disperse at a frequency of 30 kHz for 10 minutes to obtain a composite organic spinning solution.

[0021] S2: Preparation of an antibacterial and waterproof surface film material S2.1: Use a conductivity meter to continuously measure the conductivity of the composite organic spinning solution. Each time, add 0.03 wt% of tetrabutylammonium bromide and stir evenly, then observe the conductivity measured by the conductivity meter until the conductivity is 5.8 μS / cm to obtain a pre-spinning solution; S2.2: Mix nanocellulose and deionized water and conduct ultrasonic dispersion for 25 minutes to obtain a nanocellulose suspension with a concentration of 3%. Dissolve cetyltrimethoxysilane in an ethanol aqueous solution with a concentration of 95%, add acetic acid to adjust the pH to 3, and stir for 30 minutes to obtain an HDTMS solution with a concentration of 12%. Slowly add the nanocellulose suspension to the HDTMS solution at a volume ratio of 1:1, and stir at 55 °C for 8 hours to obtain a spray solution; S2.3: Add the preventive silk solution to the syringe of the electrospinning machine. Set the distance between the syringe needle and the aluminum foil roller collector to 12 cm. Connect the positive pole of the pulsed power supply to the syringe needle and the negative pole to the aluminum foil receiving plate. Conduct electrospinning under the conditions of 23 °C and 25% RH humidity. Set the syringe propulsion rate to 2 mL / h and the lateral movement speed to 2 cm / s. The pulsed power supply first spins at a voltage of 18 kV for 2 seconds, and then spins at a voltage of 26 kV for 0.5 seconds until a spun film is covered on the aluminum foil receiving plate. Then use an electrostatic sprayer to evenly spray the spray solution on the surface of the spun film. The spray voltage is 10 kV, the flow rate is 0.6 mL / h, and the spray amount is 1 mg / cm 2 , After peeling off the spun film, place it in a vacuum dryer at 60 °C for 2 hours to obtain an antibacterial and waterproof surface layer film material.

[0022] S3: Preparation of the moisture-absorbing and breathable core layer film material and lamination of the film materials S3.1: Place sodium alginate and glycidyl hexadecyl ether in a container at a molar ratio of 1:0.25, add 8 times the mass of a dimethyl sulfoxide / deionized water mixed solvent, the volume ratio of dimethyl sulfoxide to deionized water is 1:0.3, and then add 0.3 wt% of tetrabutylammonium bromide. Heat to 85 °C under nitrogen protection and react for 4 hours. Then add 4 wt% of phenylboronic acid and 0.1 wt% of hydrogen peroxide, continue to heat to 80 °C under nitrogen protection and react for 3 hours. Then inject it into a dialysis bag with a molecular weight cut-off of 3200 Da and dialyze in flowing deionized water for 72 hours, and freeze-dry to obtain modified sodium alginate; S3.2: Mix the modified sodium alginate and polyethylene terephthalate with a viscosity of 0.8 dL / g at a mass ratio of 1:8, add 0.4 wt% of methyltin isooctyl mercaptoacetate and 0.6 wt% of silane coupling agent KH-550, mix evenly and place it in a twin-screw extruder. Set the temperature of zone I to 240 °C, the temperature of zone II to 250 °C, and the temperature of zone III to 265 °C. Extrude the melt and cool it. When it cools to 100 °C, maintain the temperature and conduct longitudinal and transverse stretching until a 100-μm thin film is formed to obtain the moisture-absorbing and breathable core layer film material; S3.3: Heat the moisture-absorbing and breathable core layer film material to 140 °C, place it in a mold in the sandwich structure of antibacterial and waterproof surface layer film material - moisture-absorbing and breathable core layer film material - antibacterial and waterproof surface layer film material, and then use a molding press for lamination. The molding temperature is 60 °C, the molding pressure is 4 MPa, and a composite functional waterproof and breathable film is obtained after cooling.

[0023] Example 2 A preparation method of a composite functional waterproof and breathable film, as Figure 1 shown, includes the following steps: S1: Preparation of composite organic spinning solution S1.1: Add the secretion of Chinese wax scale insects to an ethanol solution with a concentration of 70% according to a material-liquid ratio of 1:10 g / mL, perform water bath oscillation at 45 °C and 120 rpm for 1.5 hours, then pass through a 400-mesh sieve to obtain a crude filtrate. Mix the crude filtrate and an ethanol solution with a concentration of 95% evenly at a volume ratio of 1:3, let it stand overnight at 3 °C, then centrifuge at a speed of 4000 rpm for 10 minutes. After collecting the supernatant, add deionized water and stir until a large amount of precipitate precipitates. After centrifuging at a speed of 4000 rpm for 10 minutes, retain the precipitate and perform vacuum drying at 40 °C to obtain a purified Chinese wax. S1.2: Mix acetone and hexafluoroisopropanol in a volume ratio of 4:10 and place them in a container, stir magnetically for 30 minutes to obtain a mixed solvent, then add 30 wt% of polyethylene terephthalate with a molecular weight of 25000, and stir at a constant temperature water bath of 60 °C for 2 hours until completely dissolved to obtain a PET spinning solution. S1.3: Ultrasonically disperse 2-carene and dragon's blood powder in acetone according to a mass ratio of 1:5, with an ultrasonic frequency of 25 kHz and an ultrasonic time of 8 minutes to obtain a composite suspension with a dragon's blood powder concentration of 3%. Take the PET spinning solution and place it in a container. First, add 1.2 wt% of the purified Chinese wax and 0.2 wt% of the fluorocarbon surfactant Capstone FS-3100, then add 25% of the volume of the composite suspension of the PET spinning solution, and ultrasonically disperse it at a frequency of 30 kHz for 10 minutes to obtain a composite organic spinning solution.

[0024] S2: Preparation of antibacterial and waterproof surface layer film material S2.1: Use a conductivity meter to measure the conductivity of the composite organic spinning solution in real time. After adding 0.05 wt% of tetrabutylammonium bromide each time and stirring evenly, then observe the conductivity measured by the conductivity meter until the conductivity is 5.8 μS / cm to obtain a pre-spinning solution. S2.2: Mix nanocellulose and deionized water and conduct ultrasonic dispersion for 25 minutes to obtain a nanocellulose suspension with a concentration of 3%. Dissolve cetyltrimethoxysilane in an ethanol aqueous solution with a concentration of 95%, add acetic acid to adjust the pH to 3, and stir for 30 minutes to obtain an HDTMS solution with a concentration of 15%. Slowly add the nanocellulose suspension to the HDTMS solution at a volume ratio of 1:2, and stir at 55 °C for 8 hours to obtain a spray solution; S2.3: Add the preventive silk solution to the syringe of the electrospinning machine. Set the distance between the syringe needle and the aluminum foil drum collector to 12 cm. Connect the positive pole of the pulsed power supply to the syringe needle and the negative pole to the aluminum foil receiving plate. Conduct electrospinning under the conditions of 23 °C and 25% RH humidity. Set the syringe propulsion rate to 2 mL / h and the lateral movement speed to 2 cm / s. The pulsed power supply first spins at a voltage of 18 kV for 2 seconds, and then spins at a voltage of 26 kV for 0.5 seconds until a layer of spun film covers the aluminum foil receiving plate. Then, use an electrostatic sprayer to evenly spray the spray solution on the surface of the spun film. The spray voltage is 10 kV, the flow rate is 0.6 mL / h, and the spray amount is 2 mg / cm 2 , After peeling off the spun film, place it in a vacuum dryer at 60 °C for 2 hours to obtain an antibacterial and waterproof surface layer film material.

[0025] S3: Preparation of the moisture-absorbing and breathable core layer film material and lamination of the film materials S3.1: Place sodium alginate and glycidyl hexadecyl ether in a container at a molar ratio of 1:0.3, add a mixed solvent of dimethyl sulfoxide / deionized water with 10 times the mass. The volume ratio of dimethyl sulfoxide to deionized water is 1:0.4. Then add 0.5 wt% of tetrabutylammonium bromide, heat to 85 °C under nitrogen protection and react for 4 hours. Then add 5 wt% of phenylboronic acid and 0.2 wt% of hydrogen peroxide, continue to heat to 80 °C under nitrogen protection and react for 3 hours. Then inject it into a dialysis bag with a molecular weight cut-off of 3200 Da and dialyze in flowing deionized water for 72 hours, and freeze-dry to obtain modified sodium alginate; S3.2: Mix the modified sodium alginate and polyethylene terephthalate with a viscosity of 0.8 dL / g at a mass ratio of 1:10, add 0.6 wt% of methyltin isooctyl mercaptoacetate and 0.8 wt% of silane coupling agent KH-550, mix evenly and place it in a twin-screw extruder. Set the temperature of zone I to 240 °C, the temperature of zone II to 250 °C, and the temperature of zone III to 265 °C. Extrude the melt and cool it. When it cools to 100 °C, maintain the temperature and conduct longitudinal and transverse stretching until a 100-μm thin film is formed to obtain the moisture-absorbing and breathable core layer film material; S3.3: The temperature for heating the moisture-absorbing and breathable core layer film material is 140 °C. Place the sandwich structure of antibacterial and waterproof surface layer film material - moisture-absorbing and breathable core layer film material - antibacterial and waterproof surface layer film material in a mold, and then use a molding press for lamination. The molding temperature is 60 °C, the molding pressure is 4 MPa, and a composite functional waterproof and breathable film is obtained after cooling.

[0026] Example 3 A preparation method of a composite functional waterproof and breathable film, as Figure 1 shown, includes the following steps: S1: Preparation of a composite organic spinning solution S1.1: Add the secretion of Chinese wax scale insects to an ethanol solution with a concentration of 75% according to a solid-liquid ratio of 1:10 g / mL, perform water bath oscillation at 50 °C and 150 rpm for 2 hours, then pass through a 500-mesh sieve to obtain a crude filtrate. Mix the crude filtrate and an ethanol solution with a concentration of 97% evenly according to a volume ratio of 1:4, let it stand overnight at 4 °C, then centrifuge at a speed of 5000 rpm for 12 minutes. After collecting the supernatant, add deionized water and stir until a large amount of precipitate precipitates. After centrifuging at a speed of 5000 rpm for 12 minutes, retain the precipitate and perform vacuum drying at 45 °C to obtain pure Chinese wax; S1.2: Mix acetone and hexafluoroisopropanol in a volume ratio of 3:7 and place them in a container, magnetically stir for 35 minutes to obtain a mixed solvent, then add 30 wt% of polyethylene terephthalate with a molecular weight of 28000, and stir at a constant water bath temperature of 65 °C for 3 hours until completely dissolved to obtain a PET spinning solution; S1.3: Ultrasonically disperse 2-carene and dragon's blood powder in acetone according to a mass ratio of 1:4, with an ultrasonic frequency of 30 kHz and an ultrasonic time of 10 minutes to obtain a composite suspension with a dragon's blood powder concentration of 2%. Take the PET spinning solution and place it in a container. First, add 1 wt% of pure Chinese wax and 0.1 wt% of fluorocarbon surfactant Capstone FS-3100, then add 20% of the volume of the composite suspension of the PET spinning solution, and ultrasonically disperse at a frequency of 35 kHz for 15 minutes to obtain a composite organic spinning solution.

[0027] S2: Preparation of an antibacterial and waterproof surface layer film material S2.1: Use a conductivity meter to continuously measure the conductivity of the composite organic spinning solution. After adding 0.03 wt% of tetrabutylammonium bromide each time and stirring evenly, then observe the conductivity measured by the conductivity meter until the conductivity is 6 μS / cm to obtain a pre-spinning solution; S2.2: Mix nanocellulose and deionized water and perform ultrasonic dispersion for 30 minutes to obtain a nanocellulose suspension with a concentration of 3%. Dissolve cetyltrimethoxysilane in an ethanol aqueous solution with a concentration of 96%, add acetic acid to adjust the pH to 4, and stir for 40 minutes to obtain an HDTMS solution with a concentration of 12%. Slowly add the nanocellulose suspension to the HDTMS solution at a volume ratio of 1:1, and stir at 60 °C for 10 hours to obtain a spray solution; S2.3: Add the preventive silk solution to the syringe of the electrospinning machine. Set the distance between the syringe needle and the aluminum foil drum collector to 15 cm. Connect the positive pole of the pulsed power supply to the syringe needle and the negative pole to the aluminum foil receiving plate. Perform electrospinning under the conditions of 27 °C and 30% RH humidity. Set the syringe propulsion rate to 3 mL / h and the lateral movement speed to 2.5 cm / s. The pulsed power supply first spins at a voltage of 20 kV for 2 seconds, and then spins at a voltage of 28 kV for 0.6 seconds until a layer of spun film covers the aluminum foil receiving plate. Then, use an electrostatic sprayer to evenly spray the spray solution on the surface of the spun film. The spray voltage is 12 kV, the flow rate is 0.8 mL / h, and the spray amount is 1 mg / cm 2 , After peeling off the spun film, place it in a vacuum dryer at 65 °C for 2.5 hours to obtain an antibacterial and waterproof surface layer film material.

[0028] S3: Preparation of the moisture-absorbing and breathable core layer film material and lamination of the film materials S3.1: Place sodium alginate and glycidyl hexadecyl ether in a container at a molar ratio of 1:0.25, add 8 times the mass of a dimethyl sulfoxide / deionized water mixed solvent. The volume ratio of dimethyl sulfoxide to deionized water is 1:0.3. Then add 0.3 wt% of tetrabutylammonium bromide, heat to 90 °C under nitrogen protection and react for 5 hours. Then add 4 wt% of phenylboronic acid and 0.1 wt% of hydrogen peroxide, continue to heat to 85 °C under nitrogen protection and react for 4 hours. Then inject it into a dialysis bag with a molecular weight cut-off of 3500 Da and dialyze in flowing deionized water for 75 hours, and freeze-dry to obtain modified sodium alginate; S3.2: Mix the modified sodium alginate and polyethylene terephthalate with a viscosity of 0.85 dL / g at a mass ratio of 1:8, add 0.3 wt% of methyltin isooctyl mercaptoacetate and 0.6 wt% of silane coupling agent KH-550, mix evenly and place it in a twin-screw extruder. Set the temperature of zone I to 245 °C, the temperature of zone II to 260 °C, and the temperature of zone III to 270 °C. Extrude the melt and cool it. When it cools to 105 °C, maintain the temperature and perform longitudinal and transverse stretching until a 200-μm thin film is formed to obtain the moisture-absorbing and breathable core layer film material; S3.3: The temperature for heating the moisture-absorbing and breathable core layer film material is 150 °C. Place the sandwich structure of antibacterial and waterproof surface layer film material - moisture-absorbing and breathable core layer film material - antibacterial and waterproof surface layer film material in a mold, and then use a molding press for pressing. The molding temperature is 70 °C, the molding pressure is 6 MPa, and a composite functional waterproof and breathable film is obtained after cooling.

[0029] Comparative Example 1 Compared with Example 1, in Comparative Example 1, step S1.3 was removed, and the composite organic spinning solution in step S2.1 was replaced with PET spinning solution. The remaining steps were the same as those in Example 1. The obtained composite functional waterproof and breathable film was denoted as Comparative Example 1.

[0030] Comparative Example 2 Compared with Example 1, in Comparative Example 2, white wax pure compound was not added in step S1.3 to obtain the composite organic spinning solution. The remaining steps were the same as those in Example 1. The obtained composite functional waterproof and breathable film was denoted as Comparative Example 2.

[0031] Comparative Example 3 Compared with Example 1, in Comparative Example 3, 2-carene was not added in step S1.3 to obtain the composite organic spinning solution. The remaining steps were the same as those in Example 1. The obtained composite functional waterproof and breathable film was denoted as Comparative Example 3.

[0032] Comparative Example 4 Compared with Example 1, in Comparative Example 4, dragon's blood resin powder was not added in step S1.3 to obtain the composite organic spinning solution. The remaining steps were the same as those in Example 1. The obtained composite functional waterproof and breathable film was denoted as Comparative Example 4.

[0033] Comparative Example 5 Compared with Example 1, in Comparative Example 5, a pulse power supply was not used in step S2.3, and spinning was carried out at a voltage of 18 kV throughout the process to obtain the antibacterial and waterproof surface layer film material. The remaining steps were the same as those in Example 1. The obtained composite functional waterproof and breathable film was denoted as Comparative Example 5.

[0034] Comparative Example 6 Compared with Example 1, in Comparative Example 6, the surface of the spinning film was not subjected to electrostatic spraying treatment with a spray solution in step S2.3 to obtain the antibacterial and waterproof surface layer film material. The remaining steps were the same as those in Example 1. The obtained composite functional waterproof and breathable film was denoted as Comparative Example 6.

[0035] Comparative Example 7 Compared with Example 1, in Comparative Example 7, step S3.1 was removed, and modified sodium alginate was not added in step S3.2 to obtain the moisture-absorbing and breathable core layer film material. The remaining steps were the same as those in Example 1. The obtained composite functional waterproof and breathable film was denoted as Comparative Example 7.

[0036] Take the composite functional waterproof and breathable membranes prepared in Examples 1-3 and Comparative Examples 1-7 as samples respectively; Contact angle test: Measure the water contact angle of the samples with a contact angle measuring instrument. Using the single-circle tangent method, select 10 different points on each sample for measurement, and finally take the average value; Moisture permeability test: Adopt the upright cup method and test the moisture permeability of the samples with a water vapor transmission rate tester. Cut 3 circles with equal areas at different positions of each sample for testing. The temperature / humidity in the box is set at 38°C and 90%RH respectively, and the experiment is cycled 6 times to record the data; Air permeability test: Use a YG461H type full-automatic air permeability tester to test the air permeability of the samples. Lay the samples flat on the test bench, randomly select 5 parts in turn for testing and record the air permeability values. Test parameters: The test pressure is 100Pa, and the test area is 20cm 2 , take the average value, and make a table of the recorded data of the contact angle, moisture permeability, and air permeability, as shown in Table 1; Mechanical property test: Use a high-speed tensile machine to test the mechanical properties of the samples in Examples 1-3. By means of unidirectional stretching, cut out strips of 5cm×1cm on the fiber membrane. The stretching rate of the instrument is 30mm / min. Each sample is tested 3 times, record the data and make a table, as shown in Table 2; Table 1: Water contact angle, moisture permeability and air permeability of the composite functional waterproof and breathable membrane

[0037] Table 2: Tensile strength of the composite functional waterproof and breathable membrane

[0038] It can be seen from the data of Example 1 and Comparative Examples 1-4 in Table 1 that adding purified white wax, 2-carene and dragon's blood to the PET spinning solution, the subsequent prepared waterproof and breathable membrane has an ultra-high water contact angle. And by removing a certain component, it can be seen that purified white wax, 2-carene and dragon's blood have a synergistic effect on the improvement of the water contact angle, and can greatly improve the waterproof performance of the waterproof and breathable membrane; It can be seen from the data of Example 1 and Comparative Examples 5-6 in Table 1 that both pulse voltage spinning and spraying and modifying nanocellulose on the surface of the spinning membrane can relatively highly improve the contact angle of the waterproof and breathable membrane, and can also greatly improve the waterproof performance of the waterproof and breathable membrane; It can be seen from the data of Example 1 and Comparative Example 7 in Table 1 that by modifying sodium alginate with glycidyl hexadecyl ether and phenylboronic acid to prepare modified sodium alginate, and extruding it with PET through a twin-screw extruder, the prepared moisture-absorbing and breathable core layer membrane material can enhance the moisture-absorbing and breathable ability of the waterproof and breathable membrane.

[0039] It can be seen from the data in Table 2 that the waterproof and breathable film also has good mechanical strength and has good durability as an external film for electronic devices.

[0040] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite functional waterproof breathable membrane, characterized in that: The following steps are involved: S1: Preparation of composite organic spinning solution Purifying and extracting the secretion of wax worm to obtain a purified wax, mixing acetone and hexafluoroisopropanol and adding polyethylene terephthalate to dissolve to obtain a PET spinning solution, ultrasonically dispersing 2-carene and dragon's blood powder in acetone to obtain a composite suspension, adding the purified wax and a surfactant to the PET spinning solution, and then adding the composite suspension to perform ultrasonic dispersion to obtain a composite organic spinning solution; S2: Preparation of antibacterial and waterproof surface membrane Tetrabutylammonium bromide is added to the composite organic spinning solution to adjust the conductivity to obtain a pre-spinning solution, nanocellulose and deionized water are prepared into a nanocellulose suspension, hexadecyltrimethoxysilane is dissolved in an ethanol aqueous solution, pH is adjusted and stirred to obtain an HDTMS solution, the nanocellulose suspension is added to the HDTMS solution and stirred to obtain a spray solution, the pre-spinning solution is spun by a pulse power supply to obtain a layer of spinning membrane, the spray solution is sprayed on the surface, and the antibacterial and waterproof surface membrane material is dried; S3: Preparation of moisture-absorbing and breathable core membrane and lamination of membrane materials Sodium alginate and glycidyl hexadecyl ether are placed in a dimethyl sulfoxide / deionized water mixed solvent, heated to react in a nitrogen atmosphere, and then phenylboric acid and hydrogen peroxide are added, and the heating reaction is continued. Modified sodium alginate is obtained after dialysis, and the modified sodium alginate is blended and extruded with polyethylene terephthalate and a heat stabilizer. The extruded melt is cooled and then stretched to obtain a hygroscopic and breathable core layer membrane material. A sandwich structure of an antibacterial and waterproof surface layer membrane material-a hygroscopic and breathable core layer membrane material-an antibacterial and waterproof surface layer membrane material is placed in a mold for molding, and cooled to obtain a composite functional waterproof and breathable membrane.

2. The method for preparing a composite functional waterproof breathable membrane according to claim 1, characterized in that: Step S1: Preparation of a composite organic spinning solution, comprising the following steps: S1.1: Add the secretion of white wax worm to an ethanol solution with a concentration of 70-75% at a solid-liquid ratio of 1:(10-12) g / mL, shake in a water bath at 45-50°C and 120-150 rpm for 1.5-2 hours, then pass through a 400-500 mesh sieve to obtain a crude filtrate, mix the crude filtrate and an ethanol solution with a concentration of 95-97% at a volume ratio of 1:(3-4), let stand overnight at 3-4°C, and then centrifuge at a speed of 4000-5000 rpm for 10-12 minutes, collect the supernatant, add deionized water and stir until a large amount of precipitate is precipitated, centrifuge at a speed of 4000-5000 rpm for 10-12 minutes, retain the precipitate, and vacuum dry at 40-45°C to obtain a purified white wax product; S1.2: Acetone and hexafluoroisopropanol are mixed in a volume ratio of (3-4): (7-10) in a container, and magnetically stirred for 30-35 minutes to obtain a mixed solvent, and then 25-30wt% of polyethylene terephthalate is added, and stirred in a constant temperature water bath at 60-65°C for 2-3 hours until completely dissolved, to obtain a PET spinning solution; S1.3: Ultrasonic dispersion of 2-carene and dragon's blood powder in acetone at a mass ratio of 1:(4-5) at an ultrasonic frequency of 25-30 kHz and an ultrasonic time of 8-10 minutes to obtain a composite suspension with a dragon's blood powder concentration of 2-3%. Place PET spinning solution in a container, first add 1-1.2wt% of purified white wax and 0.1-0.2wt% of a surfactant, then add 20-25% of the composite suspension by volume of the PET spinning solution, and ultrasonically disperse at a frequency of 30-35 kHz for 10-15 minutes to obtain a composite organic spinning solution.

3. The method for preparing a composite functional waterproof breathable membrane according to claim 2, characterized in that: Step S2: Preparation of antibacterial and waterproof surface membrane material, including the following steps: S2.1: Using a conductivity meter to test the conductivity of the composite organic spinning solution in real time, adding 0.03-0.05wt% of tetrabutylammonium bromide dropwise each time and stirring evenly, and then observing the conductivity measured by the conductivity meter until the conductivity is 5.8-6μS / cm, thereby obtaining a pre-spinning solution; S2.2: Mix nanocellulose and deionized water and perform ultrasonic dispersion for 25-30 minutes to obtain a nanocellulose suspension with a concentration of 3-5%, dissolve hexadecyltrimethoxysilane in a 95-96% ethanol aqueous solution, add acetic acid to adjust the pH to 3-4, stir for 30-40 minutes to obtain a HDTMS solution with a concentration of 12-15%, slowly add the nanocellulose suspension into the HDTMS solution at a volume ratio of 1:(1-2), stir at 55-60°C for 8-10 hours to obtain a spray solution; S2.3: Add the preventive silk solution into the syringe of the electrospinning machine, set the distance between the syringe needle and the aluminum foil drum collector to 12-15cm, connect the positive electrode of the pulse power supply to the syringe needle, and the negative electrode to the aluminum foil receiving plate, and perform electrospinning at 23-27℃ and 25-30%RH humidity. Set the syringe propulsion rate to 2-3mL / h and the lateral movement speed to 2-2.5cm / s. First, spin the pulse power supply at a voltage of 18-20kV for 2-3 seconds, and then spin at a voltage of 26-28kV for 0.5-0.6 seconds until a layer of spinning membrane is covered on the aluminum foil receiving plate. Then use an electrostatic sprayer to evenly spray the spray solution on the surface of the spinning membrane. After peeling, place it in a vacuum dryer at 60-65℃ for 2-2.5 hours to obtain an antibacterial and waterproof surface membrane material.

4. The method for preparing a composite functional waterproof breathable membrane according to claim 3, characterized in that: Step S3, preparation of the moisture-absorbing and breathable core layer membrane material and compounding of the membrane material, comprises the following steps: S3.1: Sodium alginate and glycidyl hexadecyl ether are placed in a container at a molar ratio of 1:(0.25-0.3), 8-10 times the mass of a mixed solvent of dimethyl sulfoxide / deionized water is added, the volume ratio of dimethyl sulfoxide to deionized water is 1:(0.3-0.4), 0.3-0.5wt% of tetrabutylammonium bromide is added, and the mixture is heated to 85-90°C under nitrogen protection for reaction for 4-5 hours, 4-5wt% of phenylboric acid and 0.1-0.2wt% of hydrogen peroxide are added, and the mixture is heated to 80-85°C under nitrogen protection for reaction for 3-4 hours, and then injected into a dialysis bag with a molecular weight cutoff of 3200-3500Da, dialyzed in flowing deionized water for 72-75 hours, and freeze-dried to obtain modified sodium alginate; S3.2: Modified sodium alginate and polyethylene terephthalate with a viscosity of 0.8-0.85 dL / g are mixed in a mass ratio of 1: (8-10), 0.4-0.6wt% of a heat stabilizer and 0.6-0.8wt% of a silane coupling agent KH-550 are added, the mixture is evenly mixed and placed in a twin-screw extruder, and the temperature of zone I is set to 240-245°C, the temperature of zone II is set to 250-260°C, and the temperature of zone III is set to 265-270°C. The melt is extruded and cooled. When cooled to 100-105°C, the temperature is maintained for longitudinal and transverse stretching until a film of 100-200 μm is formed to obtain a moisture-absorbing and breathable core layer membrane material; S3.3: The temperature of the hygroscopic and breathable core layer membrane material is heated to 140-150°C, and a sandwich structure of antibacterial and waterproof surface layer membrane material-hygroscopic and breathable core layer membrane material-antibacterial and waterproof surface layer membrane material is placed in a mold, and then pressed by a molding machine. The molding temperature is 60-70°C, and the molding pressure is 4-6MPa. After cooling, a composite functional waterproof and breathable membrane is obtained.

5. The method for preparing a composite functional waterproof breathable membrane according to claim 2, characterized in that: The molecular weight of polyethylene terephthalate in step S1.2 is 25000-28000.

6. The method for preparing a composite functional waterproof breathable membrane according to claim 2, characterized in that: The surfactant in step S1.3 is the fluorocarbon surfactant Capstone FS-3100.

7. The method for preparing a composite functional waterproof breathable membrane according to claim 3, characterized in that: The spray voltage of the electrostatic sprayer in step S2.3 is 10-12 kV, the flow rate is 0.6-0.8 mL / h, and the spray volume is 1-2 mg / cm 2 .

8. The method for preparing a composite functional waterproof breathable membrane according to claim 4, characterized in that: The heat stabilizer in step S3.2 is methyltinthioacetate.

9. A composite functional waterproof breathable membrane, characterized in that: The composite functional waterproof and breathable membrane is prepared by the preparation method of any one of claims 1 to 8.

10. An application of a composite functional waterproof breathable membrane, characterized in that: The composite functional waterproof breathable membrane as claimed in claim 9 is applied to the housing of an electronic device.

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