A temperature and humidity self-adaptive antibacterial breathable film and a preparation method thereof

Abstract

This application discloses a temperature and humidity adaptive antibacterial breathable membrane and its preparation method, relating to the field of breathable membrane technology. The membrane comprises 80-88 parts by weight of a polyolefin elastomer matrix, 6-10 parts by weight of a temperature and humidity dual-responsive grafted monomer, 3-5 parts by weight of a composite antibacterial nanofiller, 0.3-0.8 parts by weight of a UV crosslinking initiator, and 0.2-0.4 parts by weight of a dispersant. The temperature and humidity dual-responsive grafted monomer is composed of N-isopropylacrylamide and hydroxyethyl methacrylate in a mass ratio of (2-2.2):1. The composite antibacterial nanofiller comprises poly(N-isopropylacrylamide) thermosensitive microgel and tannic acid-silver ion in-situ chelate complex, obtained through self-anchoring composite. This application obtains a temperature and humidity dual-responsive grafted monomer by grafting it onto a polyolefin elastomer matrix, followed by self-anchoring composite with the tannic acid-silver ion in-situ chelate complex, thereby achieving adaptive temperature and humidity regulation and long-lasting broad-spectrum antibacterial effects.

Description

Technical Field

[0001] This application relates to the field of breathable membrane technology, and in particular to a temperature and humidity adaptive antibacterial breathable membrane and its preparation method. Background Technology

[0002] Breathable membranes are functional polymer film materials with a microporous permeable structure, enabling gas permeability while blocking liquids and particulate matter. With advantages such as lightweight, high flexibility, and strong adaptability, they are widely used in protective textiles, medical and health care, food preservation, and daily protective applications. As applications become more refined and sophisticated, the simple breathability and protective performance of conventional breathable membranes can no longer meet the demands. Practical applications require membranes with combined functionalities such as temperature and humidity adaptive regulation, long-lasting antibacterial properties, and high-comfort breathability. In complex temperature and humidity environments, the membrane dynamically adjusts its breathability and moisture permeability according to changes in ambient temperature and humidity, while simultaneously inhibiting bacterial and microbial growth and avoiding problems such as mold, odor, and cross-contamination. Therefore, temperature and humidity adaptive antibacterial breathable membranes have become a key research and development direction for functional film materials, possessing extremely high market application value and promising prospects.

[0003] In existing technologies, antibacterial and breathable membranes are mostly prepared by conventional polymer substrate blending modification or surface coating modification processes. The substrate is mainly selected from general polymer materials such as polyethylene, polypropylene, polyurethane, and polyvinyl alcohol. The antibacterial functional components are mostly added with inorganic or organic antibacterial agents such as chitosan, tannic acid, metal oxides, and quaternary ammonium salts. The breathable structure is formed by conventional processes such as physical stretching to form pores, hot melt casting to form pores, and adhesive coating to form pores.

[0004] However, due to the current predominance of fixed pore structures, the breathable membranes lack sufficient adaptive temperature and humidity control capabilities. Furthermore, the membrane's breathability and moisture permeability parameters are difficult to coordinate with dynamic changes in ambient temperature and humidity. Consequently, under high-temperature and high-humidity conditions, insufficient membrane pore permeability prevents timely expulsion of internal moisture and heat, leading to stuffiness, dampness, and moisture retention, severely impacting user comfort. Conversely, in low-temperature and low-humidity environments, excessive pore permeability results in internal temperature and humidity loss, failing to meet insulation and moisture retention requirements. Simultaneously, when antibacterial breathable membranes are loaded with antibacterial components through simple blending or surface coating, a stable bonding structure between the antibacterial active substances and the polymer substrate interface is difficult to form. This leads to the gradual precipitation, detachment, and loss of antibacterial components during use, friction, and environmental wet-dry cycles, significantly reducing antibacterial performance and failing to achieve long-lasting antibacterial effects, requiring further improvement. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a temperature and humidity adaptive antibacterial and breathable membrane and its preparation method, so as to achieve the purpose of adaptively adjusting the pore size and improving the antibacterial performance and durability according to the ambient temperature and humidity. The specific solution is as follows: A temperature and humidity adaptive antibacterial and breathable membrane comprises 80-88 parts by weight of a polyolefin elastomer matrix, 6-10 parts by weight of a temperature and humidity dual-responsive grafted monomer, 3-5 parts by weight of a composite antibacterial nanofiller, 0.3-0.8 parts by weight of a UV crosslinking initiator, and 0.2-0.4 parts by weight of a dispersing agent; wherein: The temperature and humidity dual-response graft monomer is composed of N-isopropylacrylamide and hydroxyethyl methacrylate in a mass ratio of (2-2.2):1. The composite antibacterial nanofiller is obtained by self-anchoring composite of poly(N-isopropylacrylamide) thermosensitive microgel as an active carrier and tannic acid-silver ion in-situ chelate complex as an antibacterial agent.

[0006] Preferably, the ultraviolet crosslinking initiator is benzophenone; the dispersing agent is polyethylene glycol 400.

[0007] Preferably, the temperature and humidity dual-response graft monomer is dissolved in an ethanol-water mixed solvent to obtain a graft monomer solution with a mass concentration of 8-10%, and the mass ratio of ethanol to water in the ethanol-water mixed solvent is 1:(3-4).

[0008] Preferably, the preparation method of the composite antibacterial nanofiller includes step ① mixing N-isopropylacrylamide monomer with a crosslinking agent, controlling the amount of crosslinking agent added to be 2-2.5% of the mass of N-isopropylacrylamide monomer, and then preparing a monomer aqueous solution with a mass concentration of 5-7% using deionized water as a solvent; step ② stirring at a controlled temperature of 68-72℃ for 4-4.5h under a nitrogen atmosphere, and controlling the stirring speed to be 300-350r / min to obtain a microgel dispersion; step ③ uniformly adding an aqueous solution of tannic acid to the microgel dispersion at room temperature. Stir at 350-420 r / min for 1.5-2 h to obtain a tannic acid adsorbent carrier solution with a tannic acid loading of 10-12% of the mass of poly-N-isopropylacrylamide thermosensitive microgel; Step ④ Add 0.1 mol / L silver nitrate solution dropwise to the tannic acid adsorbent carrier solution, and stir at a constant temperature of 24-25℃ for 2-2.5 h while avoiding light, to obtain a mixed system with antibacterial composite particles having a silver ion loading of 15-18% of the mass of tannic acid; Step ⑤ After centrifugation, washing, drying and grinding of the mixed system, obtain an ultrafine thermosensitive self-anchored composite antibacterial nanofiller.

[0009] Preferably, the crosslinking agent is N,N'-methylenebisacrylamide.

[0010] Preferably, in step ③, the pH of the tannic acid adsorbent carrier solution is 5.5-6.0.

[0011] Preferably, in step ⑤, the centrifugation is performed at a controlled speed of 7000-8500 r / min for 10-12 min; the washing is performed by washing with deionized water 3-5 times; the drying is performed by vacuum drying at a controlled temperature of 58-62℃ for 12-14 h; and the grinding is performed by air jet grinding at a controlled temperature of 10-25℃.

[0012] The second objective of this invention is to provide a method for preparing a temperature and humidity adaptive antibacterial breathable membrane, as described above. The method includes melting and extruding a polyolefin elastomer matrix to obtain a microporous base membrane, then immersing the microporous base membrane in a solution of temperature and humidity responsive grafted monomers, performing pressure impregnation, ultraviolet graft polymerization, and cleaning and drying to obtain a graft-modified microporous base membrane. Finally, the graft-modified microporous base membrane, composite antibacterial nanofiller, and dispersant are melt-blended and cast and stretched to obtain a temperature and humidity adaptive antibacterial breathable membrane with uniform micropores.

[0013] Preferably, the preparation method of the grafted modified microporous base membrane includes step 1: feeding a polyolefin elastomer matrix into a screw extruder, controlling the temperature at 175-190℃ for melt extrusion, obtaining a microporous base membrane with a porosity of 35-40% through a casting and stretching process, and controlling the longitudinal stretching temperature at 180-190℃, the stretching ratio at 3.5-4.0 times, and the traction speed at 8-12 m / min; step 2: dissolving the temperature and humidity dual-response grafting monomer in an ethanol-water mixed solvent to obtain a grafting monomer solution with a mass concentration of 8-10%, and then applying the solution to the target material. UV crosslinking initiator is added to the grafting monomer solution, and the microporous base membrane is immersed in the grafting monomer solution for 15-20 min. Grafting polymerization is then initiated in situ by UV lamp, with the UV irradiation power controlled at 80-100W, the irradiation distance at 8-12cm, and the irradiation time at 30-50s, to obtain the grafted polymer membrane. Step 3: The grafted polymer membrane is rinsed with pure water to remove the free temperature and humidity responsive grafting monomers on the surface, and then dried at 60-70℃ for 20-30 min to obtain the grafted modified microporous base membrane.

[0014] Preferably, the melt blending temperature is 170-180℃, the stirring speed is 600-800 r / min, and the mixing time is 15-20 min; the casting and stretching molding is carried out by melt extrusion at a controlled temperature of 175-185℃, followed by controlling the longitudinal stretching temperature at 180-185℃, the transverse stretching temperature at 178-183℃, the stretching ratio at 3.5-4.0 times, the traction speed at 9-11 m / min, and then allowing it to stand and set at room temperature to obtain a temperature and humidity adaptive antibacterial and breathable membrane.

[0015] As can be seen from the above solutions, this application provides a temperature and humidity adaptive antibacterial breathable membrane and its preparation method, which have the following beneficial effects: 1. Using N-isopropylacrylamide and hydroxyethyl methacrylate as a compound dual-response grafting monomer, the microporous membrane prepared by polyolefin elastomer matrix is ​​covalently grafted to form a smart response chain segment, thereby enabling the micropores to dynamically expand and contract with the ambient temperature and humidity through the combination of temperature-sensitive phase change and reversible hydrophilic-hydrophobic conversion. 2. By using a composite antibacterial nanofiller composed of poly(N-isopropylacrylamide) thermosensitive microgel and tannic acid-silver ion in-situ chelate complex, the surface hydroxyl and amide groups of the composite antibacterial nanofiller are enhanced to form a hydrogen bond entanglement anchoring structure with the polyolefin elastomer matrix which is combined with temperature and humidity dual-responsive grafted monomers. In addition, the antibacterial agent is locked in place by polyphenol metal in-situ complexation, which effectively avoids the problems of free precipitation and migration and shedding, so as to significantly improve the antibacterial performance and antibacterial durability. 3. By using temperature and humidity dual-response grafted monomers and composite antibacterial nanofillers in synergy, the temperature-sensitive response system can effectively switch between high and low temperatures and high and low humidity. The composite antibacterial nanofillers adopt a flexible molecular entanglement anchoring structure and are attached to the micropore wall, thereby effectively avoiding affecting the air and water permeability of the micropores and achieving a long-lasting antibacterial effect. Detailed Implementation

[0016] The technical solutions described below in conjunction with the embodiments of this application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0017] It should be mentioned that the UV crosslinking initiator in the embodiments of this application is benzophenone. The dispersing aid is polyethylene glycol 400. The crosslinking agent is N,N'-methylenebisacrylamide.

[0018] The following will provide a detailed description of a temperature and humidity adaptive antibacterial and breathable membrane and its preparation method, as described in this application.

[0019] A temperature and humidity adaptive antibacterial and breathable membrane includes 80-88 parts by weight of a polyolefin elastomer matrix, 6-10 parts by weight of a temperature and humidity dual-response grafted monomer, 3-5 parts by weight of a composite antibacterial nanofiller, 0.3-0.8 parts by weight of an ultraviolet crosslinking initiator, and 0.2-0.4 parts by weight of a dispersing agent.

[0020] The temperature and humidity responsive graft monomer is composed of N-isopropylacrylamide and hydroxyethyl methacrylate in a mass ratio of (2-2.2):1. The temperature and humidity responsive graft monomer is dissolved in an ethanol-water mixed solvent to obtain a graft monomer solution with a mass concentration of 8-10%, and the mass ratio of ethanol to water in the ethanol-water mixed solvent is 1:(3-4).

[0021] The composite antibacterial nanofiller comprises a poly(N-isopropylacrylamide) thermosensitive microgel as an active carrier and a tannic acid-silver ion in-situ chelate complex as an antibacterial agent, obtained through self-anchoring composite. It should be noted that the preparation method of the composite antibacterial nanofiller includes: Step ① mixing N-isopropylacrylamide monomer with a crosslinking agent, controlling the amount of crosslinking agent added to be 2-2.5% of the mass of N-isopropylacrylamide monomer, and then preparing a monomer aqueous solution with a N-isopropylacrylamide monomer concentration of 5-7% using deionized water as a solvent; Step ② stirring at a controlled temperature of 68-72℃ for 4-4.5h under a nitrogen atmosphere, controlling the stirring speed to be 300-350 r / min to obtain a microgel dispersion; Step ③ uniformly adding a tannic acid aqueous solution to the microgel dispersion at room temperature. The mixture is stirred at a speed of 350-420 r / min for 1.5-2 h to obtain a tannic acid adsorption carrier solution with a tannic acid loading of 10-12% of the mass of poly-N-isopropylacrylamide thermosensitive microgel; Step ④: 0.1 mol / L silver nitrate solution is added dropwise to the tannic acid adsorption carrier solution, and the mixture is stirred at a constant temperature of 24-25℃ in the dark for 2-2.5 h to obtain a mixed system with antibacterial composite particles having a silver ion loading of 15-18% of the mass of tannic acid; Step ⑤: The mixed system is centrifuged, washed, dried and ground in sequence to obtain an ultrafine thermosensitive self-anchored composite antibacterial nanofiller.

[0022] In step ③, the pH of the tannic acid adsorption carrier solution is controlled at 5.5-6.0 to improve loading efficiency. In step ⑤, centrifugation is performed at a speed of 7000-8500 r / min for 10-12 min. Washing is done 3-5 times with deionized water. Drying is performed under vacuum at a temperature of 58-62℃ for 12-14 h. Grinding is performed using airflow grinding at a temperature of 10-25℃.

[0023] A method for preparing a temperature and humidity adaptive antibacterial breathable membrane, as described above, includes: melt extruding a polyolefin elastomer matrix to obtain a microporous base membrane; immersing the microporous base membrane in a solution of temperature and humidity responsive grafted monomers, followed by pressure impregnation, ultraviolet graft polymerization, cleaning, and drying to obtain a graft-modified microporous base membrane; finally, melt-blending the graft-modified microporous base membrane, composite antibacterial nanofillers, and dispersing agents, controlling the melt-blending temperature at 170-180℃, the stirring speed at 600-800 r / min, and the mixing time at 15-20 min; then melt-extruding the membrane at a controlled temperature of 175-185℃; controlling the longitudinal stretching temperature at 180-185℃, the transverse stretching temperature at 178-183℃, the stretching ratio at 3.5-4.0 times, and the traction speed at 9-11 m / min; and finally, casting and stretching the membrane at room temperature to obtain a uniformly microporous temperature and humidity adaptive antibacterial breathable membrane.

[0024] It should be noted that the preparation method of the grafted modified microporous membrane includes step 1: feeding the polyolefin elastomer matrix into a screw extruder, controlling the temperature at 175-190℃ for melt extrusion, and obtaining a microporous membrane with a porosity of 35-40% through a casting and stretching process, controlling the longitudinal stretching temperature at 180-190℃, the stretching ratio at 3.5-4.0 times, and the traction speed at 8-12 m / min; step 2: dissolving the temperature and humidity responsive grafting monomer in an ethanol-water mixed solvent to obtain a grafting monomer solution with a mass concentration of 8-10%. Add a UV crosslinking initiator to the grafting monomer solution, immerse the microporous base membrane in the grafting monomer solution for 15-20 min, and then initiate grafting polymerization in situ with a UV lamp. Control the UV irradiation power to be 80-100W, the irradiation distance to be 8-12cm, and the irradiation time to be 30-50s to obtain a grafted polymer membrane. Step 3: Rinse the grafted polymer membrane with pure water to remove the free temperature and humidity responsive grafting monomers on the surface, and then dry it at a temperature of 60-70℃ for 20-30 min to obtain a grafted modified microporous base membrane.

[0025] Example 1 A temperature and humidity adaptive antibacterial and breathable membrane comprises 80 parts by weight of a polyolefin elastomer matrix, 6 parts by weight of a temperature and humidity dual-response grafted monomer, 3 parts by weight of a composite antibacterial nanofiller, 0.3 parts by weight of an ultraviolet crosslinking initiator, and 0.2 parts by weight of a dispersing agent.

[0026] The temperature and humidity responsive graft monomer is composed of N-isopropylacrylamide and hydroxyethyl methacrylate in a mass ratio of 2:1. The temperature and humidity responsive graft monomer is dissolved in an ethanol-water mixed solvent to obtain an 8% (w / w) graft monomer solution, with the mass ratio of ethanol to water in the ethanol-water mixed solvent being 1:3.

[0027] The composite antibacterial nanofiller comprises a poly(N-isopropylacrylamide) thermosensitive microgel as an active carrier and a tannic acid-silver ion in-situ chelate complex as an antibacterial agent, obtained through self-anchoring composite. It should be noted that the preparation method of the composite antibacterial nanofiller includes: Step ① mixing N-isopropylacrylamide monomer with a crosslinking agent, controlling the amount of crosslinking agent added to be 2% of the mass of N-isopropylacrylamide monomer, and then preparing a monomer aqueous solution with a N-isopropylacrylamide monomer concentration of 5% using deionized water as a solvent; Step ② stirring at a controlled temperature of 68℃ for 4 hours under a nitrogen atmosphere and controlling the stirring speed at 300 r / min to obtain a microgel dispersion; Step ③ uniformly adding a tannic acid aqueous solution to the microgel dispersion at a constant rate, and stirring at room temperature. The mixture was stirred at 350 r / min for 1.5 h to obtain a tannic acid adsorption carrier solution with a tannic acid loading of 10.2% of the mass of poly-N-isopropylacrylamide thermosensitive microgel; Step ④: 0.1 mol / L silver nitrate solution was added dropwise to the tannic acid adsorption carrier solution, and the mixture was stirred at a constant temperature of 24℃ for 2 h while avoiding light to obtain a mixed system of antibacterial composite particles with a silver ion loading of 16.54% of the mass of tannic acid; Step ⑤: The mixed system was centrifuged, washed, dried and ground in sequence to obtain an ultrafine thermosensitive self-anchored composite antibacterial nanofiller.

[0028] In step ③, the pH of the tannic acid adsorption carrier solution is controlled to be 5.5-6.0, and limiting the fluctuation range to pH 5.5-6.0 will effectively improve the loading efficiency. In step ⑤, centrifugation is performed at a controlled speed of 7000 r / min for 10 min. Washing is performed three times with deionized water. Drying is performed under vacuum at a controlled temperature of 58℃ for 12 h. Grinding is performed under airflow grinding at a controlled temperature of 10℃.

[0029] A method for preparing a temperature and humidity adaptive antibacterial breathable membrane, as described above, includes: melt extruding a polyolefin elastomer matrix to obtain a microporous base membrane; immersing the microporous base membrane in a solution of temperature and humidity responsive grafted monomers, followed by pressure impregnation, ultraviolet graft polymerization, cleaning, and drying to obtain a graft-modified microporous base membrane; finally, melt-blending the graft-modified microporous base membrane, composite antibacterial nanofillers, and dispersing agents, controlling the melt-blending temperature at 170℃, the stirring speed at 600 r / min, and the mixing time at 15 min; then, after melt extrusion at a controlled temperature of 175℃, controlling the longitudinal stretching temperature at 180℃, the transverse stretching temperature at 178℃, the stretching ratio at 3.5 times, and the traction speed at 9 m / min; and finally, casting and stretching at room temperature to obtain a uniformly microporous temperature and humidity adaptive antibacterial breathable membrane.

[0030] It should be noted that the preparation method of the grafted modified microporous base membrane includes the following steps: Step 1: The polyolefin elastomer matrix is ​​fed into a screw extruder and melt-extruded at a controlled temperature of 175℃. The microporous base membrane with a porosity of 35.1% is obtained through a casting and stretching process, and the longitudinal stretching temperature is controlled at 180℃, the stretching ratio is 3.5 times, and the traction speed is 8m / min; Step 2: The temperature and humidity dual-response grafting monomer is dissolved in an ethanol-water mixed solvent to obtain a grafting monomer solution with a mass concentration of 8%. An ultraviolet crosslinking initiator is added to the grafting monomer solution, and the microporous base membrane is immersed in the grafting monomer solution for 15min. Then, graft polymerization is initiated in situ by ultraviolet lamp, and the ultraviolet irradiation power is controlled at 80W, the irradiation distance is 8cm, and the irradiation time is 30s to obtain a grafted polymer membrane; Step 3: The grafted polymer membrane is rinsed with pure water to remove the free temperature and humidity dual-response grafting monomer on the surface, and then dried at a controlled temperature of 60℃ for 20min to obtain the grafted modified microporous base membrane.

[0031] Example 2 A temperature and humidity adaptive antibacterial and breathable membrane comprises 84 parts by weight of a polyolefin elastomer matrix, 8 parts by weight of a temperature and humidity dual-response grafted monomer, 4 parts by weight of a composite antibacterial nanofiller, 0.5 parts by weight of an ultraviolet crosslinking initiator, and 0.3 parts by weight of a dispersing agent.

[0032] The temperature and humidity responsive graft monomer is composed of N-isopropylacrylamide and hydroxyethyl methacrylate in a mass ratio of 2.1:1. The temperature and humidity responsive graft monomer is dissolved in an ethanol-water mixed solvent to obtain a graft monomer solution with a mass concentration of 9%, and the mass ratio of ethanol to water in the ethanol-water mixed solvent is 1:3.5.

[0033] The composite antibacterial nanofiller comprises a poly(N-isopropylacrylamide) thermosensitive microgel as an active carrier and a tannic acid-silver ion in-situ chelate complex as an antibacterial agent, obtained through self-anchoring composite. It should be noted that the preparation method of the composite antibacterial nanofiller includes: Step ① mixing N-isopropylacrylamide monomer with a crosslinking agent, controlling the amount of crosslinking agent added to be 2.2% of the mass of N-isopropylacrylamide monomer, and then preparing a monomer aqueous solution with a N-isopropylacrylamide monomer concentration of 6% using deionized water as a solvent; Step ② stirring at a controlled temperature of 70℃ for 4.2h under a nitrogen atmosphere and a stirring speed of 320r / min to obtain a microgel dispersion; Step ③ uniformly adding a tannic acid aqueous solution to the microgel dispersion, and stirring at room temperature. The mixture was stirred at 400 r / min for 1.8 h to obtain a tannic acid adsorption carrier solution with a tannic acid loading of 10.9% of the mass of poly-N-isopropylacrylamide thermosensitive microgel. In step ④, 0.1 mol / L silver nitrate solution was added dropwise to the tannic acid adsorption carrier solution, and the mixture was stirred at a constant temperature of 24℃ for 2.2 h while avoiding light, to obtain a mixed system of antibacterial composite particles with a silver ion loading of 17.15% of the mass of tannic acid. In step ⑤, the mixed system was centrifuged, washed, dried, and ground in sequence to obtain an ultrafine thermosensitive self-anchored composite antibacterial nanofiller.

[0034] In step ③, the pH of the tannic acid adsorption carrier solution is controlled to be 5.5-6.0, and limiting the fluctuation range to pH 5.5-6.0 will effectively improve the loading efficiency. In step ⑤, centrifugation is performed at a controlled speed of 8000 r / min for 11 min. Washing is performed 4 times with deionized water. Drying is performed under vacuum at a controlled temperature of 60℃ for 13 h. Grinding is performed under airflow grinding at a controlled temperature of 15℃.

[0035] A method for preparing a temperature and humidity adaptive antibacterial breathable membrane, as described above, includes: melt extruding a polyolefin elastomer matrix to obtain a microporous base membrane; immersing the microporous base membrane in a solution of temperature and humidity responsive grafted monomers, followed by pressure impregnation, ultraviolet graft polymerization, cleaning, and drying to obtain a graft-modified microporous base membrane; finally, melt-blending the graft-modified microporous base membrane, composite antibacterial nanofillers, and dispersing agents, controlling the melt-blending temperature at 175℃, the stirring speed at 700 r / min, and the mixing time at 18 min; then, after melt extrusion at a controlled temperature of 180℃, controlling the longitudinal stretching temperature at 182℃, the transverse stretching temperature at 180℃, the stretching ratio at 3.8 times, and the traction speed at 10 m / min; and finally, casting and stretching at room temperature to obtain a uniformly microporous temperature and humidity adaptive antibacterial breathable membrane.

[0036] It should be noted that the preparation method of the grafted modified microporous base membrane includes the following steps: Step 1: The polyolefin elastomer matrix is ​​fed into a screw extruder and melt-extruded at a controlled temperature of 180℃. The microporous base membrane with a porosity of 36.3% is obtained through a casting and stretching process, and the longitudinal stretching temperature is controlled at 185℃, the stretching ratio is 3.8 times, and the traction speed is 10m / min; Step 2: The temperature and humidity dual-response grafting monomer is dissolved in an ethanol-water mixed solvent to obtain a grafting monomer solution with a mass concentration of 9%. An ultraviolet crosslinking initiator is added to the grafting monomer solution, and the microporous base membrane is immersed in the grafting monomer solution for 18min. Then, graft polymerization is initiated in situ by ultraviolet lamp, and the ultraviolet irradiation power is controlled at 90W, the irradiation distance is 10cm, and the irradiation time is 40s to obtain a grafted polymer membrane; Step 3: The grafted polymer membrane is rinsed with pure water to remove the free temperature and humidity dual-response grafting monomer on the surface, and then dried at a controlled temperature of 65℃ for 25min to obtain the grafted modified microporous base membrane.

[0037] Example 3 A temperature and humidity adaptive antibacterial and breathable membrane comprises 88 parts by weight of a polyolefin elastomer matrix, 10 parts by weight of a temperature and humidity dual-response grafted monomer, 5 parts by weight of a composite antibacterial nanofiller, 0.8 parts by weight of an ultraviolet crosslinking initiator, and 0.4 parts by weight of a dispersing agent.

[0038] The temperature and humidity responsive graft monomer is composed of N-isopropylacrylamide and hydroxyethyl methacrylate in a mass ratio of 2.2:1. The temperature and humidity responsive graft monomer is dissolved in an ethanol-water mixed solvent to obtain a 10% (w / w) graft monomer solution, with the ethanol to water mass ratio being 1:4.

[0039] The composite antibacterial nanofiller comprises a poly(N-isopropylacrylamide) thermosensitive microgel as an active carrier and a tannic acid-silver ion in-situ chelate complex as an antibacterial agent, obtained through self-anchoring composite. It should be noted that the preparation method of the composite antibacterial nanofiller includes: Step ① mixing N-isopropylacrylamide monomer with a crosslinking agent, controlling the amount of crosslinking agent added to be 2.5% of the mass of N-isopropylacrylamide monomer, and then preparing a monomer aqueous solution with a mass concentration of 7% using deionized water as a solvent; Step ② stirring at a controlled temperature of 72℃ for 4.5h under a nitrogen atmosphere and a stirring speed of 350r / min to obtain a microgel dispersion; Step ③ uniformly adding a tannic acid aqueous solution to the microgel dispersion at room temperature and stirring. The mixture was stirred at 420 r / min for 2 h to obtain a tannic acid adsorption carrier solution with a tannic acid loading of 11.7% of the mass of poly-N-isopropylacrylamide thermosensitive microgel. In step ④, 0.1 mol / L silver nitrate solution was added dropwise to the tannic acid adsorption carrier solution, and the mixture was stirred at a constant temperature of 25℃ for 2.5 h while avoiding light, to obtain a mixed system of antibacterial composite particles with a silver ion loading of 17.63% of the mass of tannic acid. In step ⑤, the mixed system was centrifuged, washed, dried, and ground in sequence to obtain an ultrafine thermosensitive self-anchored composite antibacterial nanofiller.

[0040] In step ③, controlling the pH of the tannic acid adsorption carrier solution to 5.5-6.0, with fluctuations limited to this range, will effectively improve loading efficiency. In step ⑤, centrifugation is performed at a controlled speed of 8500 r / min for 12 min. Washing involves five washes with deionized water. Drying is performed under vacuum at 62℃ for 14 h. Grinding is performed using an air jet mill at 25℃.

[0041] A method for preparing a temperature and humidity adaptive antibacterial breathable membrane, as described above, includes: melt extruding a polyolefin elastomer matrix to obtain a microporous base membrane; immersing the microporous base membrane in a solution of temperature and humidity responsive grafted monomers, followed by pressure impregnation, ultraviolet graft polymerization, cleaning, and drying to obtain a graft-modified microporous base membrane; finally, melt-blending the graft-modified microporous base membrane, composite antibacterial nanofillers, and dispersing agents, controlling the melt-blending temperature at 180℃, the stirring speed at 800 r / min, and the mixing time at 20 min; then, after melt extrusion at a controlled temperature of 185℃, controlling the longitudinal stretching temperature at 185℃, the transverse stretching temperature at 183℃, the stretching ratio at 4.0 times, and the traction speed at 11 m / min; and finally, casting and stretching at room temperature to obtain a uniformly microporous temperature and humidity adaptive antibacterial breathable membrane.

[0042] It should be noted that the preparation method of the grafted modified microporous base membrane includes the following steps: Step 1: The polyolefin elastomer matrix is ​​fed into a screw extruder and melt-extruded at a controlled temperature of 190℃. The microporous base membrane with a porosity of 39.5% is obtained through a casting and stretching process, and the longitudinal stretching temperature is controlled at 190℃, the stretching ratio is 4.0 times, and the traction speed is 12m / min; Step 2: The temperature and humidity dual-response grafting monomer is dissolved in an ethanol-water mixed solvent to obtain a grafting monomer solution with a mass concentration of 10%. An ultraviolet crosslinking initiator is added to the grafting monomer solution, and the microporous base membrane is immersed in the grafting monomer solution for 20min. Then, graft polymerization is initiated in situ by ultraviolet lamp, and the ultraviolet irradiation power is controlled at 100W, the irradiation distance is 12cm, and the irradiation time is 50s to obtain a grafted polymer membrane; Step 3: The grafted polymer membrane is rinsed with pure water to remove the free temperature and humidity dual-response grafting monomer on the surface, and then dried at a controlled temperature of 70℃ for 30min to obtain the grafted modified microporous base membrane.

[0043] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that Comparative Example 1 did not add a temperature and humidity dual-response graft monomer.

[0044] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that in Comparative Example 2, nano-silver antibacterial filler is used instead of composite antibacterial nanofiller.

[0045] Performance testing: 1. Air permeability: According to GB / T 5453-1997 "Textiles - Determination of air permeability of fabrics", the standard pattern was tested at a pressure difference of 100 Pa and a test area of ​​20 cm². 2 The air permeability of the membrane was measured at room temperature, in mm / s. 2. Temperature and humidity adaptive response performance: The air permeability was tested under high temperature and high humidity conditions of 38℃ and RH90% and low temperature and low humidity conditions of 10℃ and RH30%, and the air permeability change rate was calculated. 3. Initial antibacterial properties: According to GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles by shaking method", Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 8099) were selected and the inhibition rate was calculated after constant temperature shaking culture; 4. Antibacterial durability performance: According to GB / T 20944.3-2008 "Water washing durability test", the standard sample was subjected to 50 standard water washing cycles to test the antibacterial rate after water washing; The performance test results are shown in Table 1 below.

[0046] Table 1 Performance Test Results

[0047] As can be seen from Table 1 above, the adaptive response capability, antibacterial performance and durability of the embodiments of this application are significantly improved compared with Comparative Example 1 and Comparative Example 2. It can be seen that the temperature and humidity dual-response grafted monomer plays the role of intelligent temperature and humidity regulation, and the composite antibacterial nanofiller plays the role of long-term antibacterial effect, and achieves synergistic improvement of air permeability and antibacterial effect in the process of their synergy.

[0048] Specifically, in Comparative Example 1, the absence of a dual-response grafted monomer resulted in a fixed physical pore structure in the micropores without the grafted temperature-sensitive segments. Consequently, the air permeability did not fluctuate accordingly with changes in temperature and humidity, lacking adaptive adjustment capability. In contrast, Examples 1 to 3 of this application utilize covalent grafting of N-isopropylacrylamide / hydroxyethyl methacrylate composite monomers onto the pore walls to form a temperature-sensitive hydrophilic-hydrophobic inverse conversion structure. This allows the hydrophilic segments to expand and open the micropores under high temperature and high humidity, significantly increasing air permeability, while under low temperature and low humidity, the hydrophobic segments shrink and contract the pore size, achieving adaptive downward adjustment of air permeability.

[0049] Meanwhile, in Comparative Example 2, because the nano-silver antibacterial filler is physically dispersed, silver ions migrate, precipitate, and detach during use due to washing and friction, resulting in a significant decrease in antibacterial performance. In contrast, Examples 1 to 3 of this application employ an in-situ tannic acid-silver ion chelate complex, which binds the polyphenol structure to silver ions. This synergistically forms a hydrogen-bonded entanglement self-anchoring structure between the poly(N-isopropylacrylamide) thermosensitive microgel and the grafted modified microporous membrane grafted with temperature and humidity-responsive monomers, effectively preventing the release and detachment of the antibacterial agent.

[0050] In summary, this application provides a temperature and humidity adaptive antibacterial breathable membrane and its preparation method. Firstly, this method employs a dual-response grafted monomer, N-isopropylacrylamide, and hydroxyethyl methacrylate, which is covalently grafted onto a microporous membrane prepared from a polyolefin elastomer matrix to form intelligent responsive segments. This allows the micropores to dynamically adjust their pore size according to ambient temperature and humidity through a combination of temperature-sensitive phase change and reversible hydrophilic-hydrophobic conversion. Secondly, a composite antibacterial nanofiller, composed of poly(N-isopropylacrylamide) temperature-sensitive microgel and tannic acid-silver ion in-situ chelate complex, is used. This enhances the formation of hydrogen-bonded entanglement and anchoring structures between the surface hydroxyl and amide groups of the composite antibacterial nanofiller and the polyolefin elastomer matrix bound by the temperature and humidity dual-response grafted monomer. Furthermore, the antibacterial agent is in-situ complexed and locked by polyphenol metals, effectively preventing the problems of free release and migration, thereby significantly improving antibacterial performance and durability. Therefore, the temperature and humidity adaptive antibacterial breathable membrane prepared by this method achieves effective conversion between high and low temperatures and high and low humidity through the synergistic effect of temperature and humidity dual-response grafted monomers and composite antibacterial nanofillers. Furthermore, the composite antibacterial nanofillers adopt a flexible molecular entanglement anchoring structure and are attached to the micropore wall, thereby effectively avoiding affecting the air and water permeability of the micropores and achieving a long-lasting antibacterial effect.

[0051] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.

[0052] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0053] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A temperature and humidity adaptive antibacterial and breathable membrane, characterized in that, It includes 80-88 parts by weight of a polyolefin elastomer matrix, 6-10 parts of a temperature and humidity responsive grafted monomer, 3-5 parts of a composite antibacterial nanofiller, 0.3-0.8 parts of a UV crosslinking initiator, and 0.2-0.4 parts of a dispersing agent; wherein: The temperature and humidity dual-response graft monomer is composed of N-isopropylacrylamide and hydroxyethyl methacrylate in a mass ratio of (2-2.2):

1. The composite antibacterial nanofiller comprises mixing N-isopropylacrylamide monomer with a crosslinking agent, adding deionized water, stirring and dispersing under an inert gas atmosphere, then adding tannic acid aqueous solution and stirring to react, and finally adding silver nitrate solution and stirring at a constant temperature to obtain an ultrafine temperature-sensitive self-anchoring composite antibacterial nanofiller.

2. The temperature and humidity adaptive antibacterial and breathable membrane according to claim 1, characterized in that: The ultraviolet crosslinking initiator is benzophenone; the dispersing agent is polyethylene glycol 400.

3. The temperature and humidity adaptive antibacterial and breathable membrane according to claim 1, characterized in that: The temperature and humidity dual-response graft monomer is dissolved in an ethanol-water mixed solvent to obtain a graft monomer solution with a mass concentration of 8-10%, and the mass ratio of ethanol to water in the ethanol-water mixed solvent is 1:(3-4).

4. The temperature and humidity adaptive antibacterial and breathable membrane according to claim 1, characterized in that: The preparation method of the composite antibacterial nanofiller includes step ① mixing N-isopropylacrylamide monomer with a crosslinking agent, controlling the amount of crosslinking agent added to be 2-2.5% of the mass of N-isopropylacrylamide monomer, and then preparing a monomer aqueous solution with a mass concentration of 5-7% using deionized water as a solvent; step ② stirring at a controlled temperature of 68-72℃ for 4-4.5h under a nitrogen atmosphere and controlling the stirring speed to be 300-350r / min to obtain a microgel dispersion; step ③ uniformly adding tannic acid aqueous solution to the microgel dispersion, and stirring at room temperature. Stir at a stirring speed of 350-420 r / min for 1.5-2 h to obtain a tannic acid adsorption carrier solution with a tannic acid loading of 10-12% of the mass of poly-N-isopropylacrylamide thermosensitive microgel; Step ④ Add 0.1 mol / L silver nitrate solution dropwise to the tannic acid adsorption carrier solution, and stir at a constant temperature of 24-25℃ for 2-2.5 h while avoiding light to obtain a mixed system with antibacterial composite particles having a silver ion loading of 15-18% of the mass of tannic acid; Step ⑤ After centrifugation, washing, drying and grinding of the mixed system, obtain an ultrafine thermosensitive self-anchored composite antibacterial nanofiller.

5. The temperature and humidity adaptive antibacterial and breathable membrane according to claim 4, characterized in that: The crosslinking agent is N,N'-methylenebisacrylamide.

6. The temperature and humidity adaptive antibacterial and breathable membrane according to claim 4, characterized in that: In step ③, the pH of the tannic acid adsorbent carrier solution is 5.5-6.

0.

7. The temperature and humidity adaptive antibacterial and breathable membrane according to claim 4, characterized in that: In step ⑤, the centrifugation is performed at a controlled speed of 7000-8500 r / min for 10-12 min; the washing is performed by washing with deionized water 3-5 times; the drying is performed by vacuum drying at a controlled temperature of 58-62℃ for 12-14 h; and the grinding is performed by air jet grinding at a controlled temperature of 10-25℃.

8. A method for preparing a temperature and humidity adaptive antibacterial and breathable membrane, used to prepare a temperature and humidity adaptive antibacterial and breathable membrane as described in any one of claims 1-7, characterized in that: The process involves melting and extruding a polyolefin elastomer matrix to obtain a microporous base membrane, then immersing the microporous base membrane in a solution of temperature and humidity-responsive grafted monomers for pressure impregnation, UV grafting polymerization, cleaning, and drying to obtain a graft-modified microporous base membrane; finally, melting and blending the graft-modified microporous base membrane, composite antibacterial nanofillers, and dispersing agents, and then casting and stretching to obtain a temperature and humidity-adaptive antibacterial and breathable membrane with uniform micropores.

9. The method for preparing a temperature and humidity adaptive antibacterial and breathable membrane according to claim 8, characterized in that: The preparation method of the grafted modified microporous base membrane includes step 1: feeding a polyolefin elastomer matrix into a screw extruder, controlling the temperature at 175-190℃ for melt extrusion, and obtaining a microporous base membrane with a porosity of 35-40% through a casting and stretching process, controlling the longitudinal stretching temperature at 180-190℃, the stretching ratio at 3.5-4.0 times, and the traction speed at 8-12 m / min; step 2: dissolving the temperature and humidity dual-response grafting monomer in an ethanol-water mixed solvent to obtain a grafting monomer solution with a mass concentration of 8-10%, and grafting the modified microporous base membrane onto the grafting membrane. UV crosslinking initiator is added to monomer solution, and microporous base membrane is immersed in graft monomer solution for 15-20 min, and then graft polymerization is initiated in situ by UV lamp. The UV irradiation power is controlled at 80-100W, the irradiation distance is 8-12cm, and the irradiation time is 30-50s to obtain graft polymer membrane; Step 3: Graft polymer membrane is rinsed with pure water to remove free temperature and humidity dual-response graft monomer on the surface, and then dried at 60-70℃ for 20-30 min to obtain graft modified microporous base membrane.

10. The method for preparing a temperature and humidity adaptive antibacterial and breathable membrane according to claim 8, characterized in that: The melt blending temperature is 170-180℃, the stirring speed is 600-800 r / min, and the mixing time is 15-20 min; the casting and stretching molding is carried out by melt extrusion at a controlled temperature of 175-185℃, followed by controlling the longitudinal stretching temperature at 180-185℃, the transverse stretching temperature at 178-183℃, the stretching ratio at 3.5-4.0 times, the traction speed at 9-11 m / min, and then allowing it to stand at room temperature to set, thereby obtaining a temperature and humidity adaptive antibacterial and breathable membrane.

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