Air filtering membrane for medical infusion apparatus and preparation method of air filtering membrane

Abstract

The invention discloses an air filtering membrane for a medical infusion apparatus and a preparation method of the air filtering membrane, and relates to the technical field of filtering materials. The prepared air filtering membrane for the medical infusion apparatus is prepared by compounding a polyvinyl alcohol condensed biphenyl dicarboxaldehyde fiber layer and a polyethylene porous membrane, and the cross-linked polyvinyl alcohol condensed biphenyl dicarboxaldehyde fiber layer is prepared by performing a reaction on biphenyl dicarboxaldehyde, sulfydryl Schiff base phosphate and polyvinyl alcohol, then performing a reaction with modified polyethyleneimine and performing wet spinning. After being compounded with the polyethylene porous membrane, the air filter membrane not only keeps good air permeability, but also has good chemical resistance and high-temperature dimensional stability, so that the stability of the air filter membrane is ensured; the polyethylene porous membrane is prepared by carrying out plasma treatment on a polyethylene membrane and then grafting polysiloxane tannic acid ester on the surface of the polyethylene membrane, and the polysiloxane tannic acid ester is prepared by reacting hydroxyl polysiloxane with a tannic acid ester polymer, so that the binding force with the cross-linked polyvinyl acetal dicarboxaldehyde fiber layer is improved, and the stability of the air filtering membrane is further ensured.

Description

Technical Field

[0001] This invention relates to the field of filtration materials technology, specifically to an air filter membrane for medical infusion devices and its preparation method. Background Technology

[0002] Air filters are indispensable components of infusion and injection devices. On one hand, they prevent various particulate matter and potentially carried bacteria and viruses from entering the medication solution and threatening patient safety; on the other hand, they maintain the pressure within the infusion set, ensuring smooth infusion. It has been reported that airborne particles can enter the medication solution through the air inlet tube, and the concentration of insoluble particles in the medication solution can vary by more than 20 times depending on the air environment. Therefore, the medical process places higher demands on the core component of air filters—the membrane—requiring it to possess characteristics such as good air permeability, retention capacity, high water resistance, strong hydrophobicity, and water resistance.

[0003] In the prior art, porous filter membranes made of pure polyethylene are used to make fiber films with a diameter of micrometers. Although these films can effectively prevent the outflow of medicine during infusion and allow air to enter, they have significant stability issues. Therefore, this invention studies and prepares an air filter membrane for medical infusion devices with high stability and filtration performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an air filter membrane for medical infusion devices with high stability and filtration performance, which is prepared by compositing a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer with a polyethylene porous membrane, and the preparation method thereof.

[0005] The present invention provides a technical solution to solve the above-mentioned technical problems: an air filter membrane for medical infusion devices, which is made of a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer and a polyethylene porous membrane; the cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer is prepared by reacting biphenyl aldehyde, mercapto-Schiff base phosphate and polyvinyl alcohol, and then reacting with modified polyethyleneimine, followed by wet spinning; the polyethylene porous membrane is prepared by plasma treating a polyethylene membrane and then grafting polysiloxane tannin onto its surface.

[0006] Preferably, the mercapto-Schiff base phosphate is prepared by reacting trimethylolpropane tris(3-mercaptopropionate), phosphate acrylate, ethylenediamine, and vanillin; the modified polyethyleneimine is prepared by reacting polyethyleneimine with a carboxyl-terminated hyperbranched polyester.

[0007] Preferably, the polysiloxane tannic acid ester is prepared by reacting hydroxyl polysiloxane with a tannic acid ester polymer; the tannic acid ester polymer is prepared by reacting tannic acid with methyltetrahydrophthalic anhydride.

[0008] Preferably, the plasma treatment is oxygen plasma treatment.

[0009] Preferably, the method for preparing the air filter membrane for medical infusion devices includes the following specific steps: S1. Polyethyleneimine, carboxyl-terminated hyperbranched polyester, and xylene are mixed in a mass ratio of 160-180:24:45. After stirring evenly, benzyltriethylammonium chloride catalyst (0.001-0.002 times the mass of polyethyleneimine) is added. The mixture is heated to 120-130℃ and reacted for 8-10 hours. The mixture is then distilled under reduced pressure, washed 3-5 times with deionized water, and dried under vacuum at 60-70℃ to obtain modified polyethyleneimine. S2. Biphenyl dicarboxaldehyde, mercapto-Schiff base phosphate, and dimethyl sulfoxide are mixed in a mass ratio of 18-22:45:300. The pH is adjusted to 3-4 with hydrochloric acid, and the temperature is raised to 50-52°C. The mixture is stirred at 200-400 rpm for 12-14 hours. The pH is neutralized to 6-7 with saturated sodium bicarbonate solution. Then, 8-10 times the mass of biphenyl dicarboxaldehyde in a polyvinyl alcohol dimethyl sulfoxide solution with a mass fraction of 8-10% and 0.001-0.002 times the mass of biphenyl dicarboxaldehyde in a catalyst p-toluenesulfonic acid are added. The temperature is raised to 40-50°C and the reaction is carried out for 1-2 hours. The temperature is raised to 75-78°C and the reaction is carried out for 4-6 hours. The mixture is precipitated with ice water and anhydrous ethanol 3-5 times. The mixture is then dried under vacuum at 60-70°C to obtain cross-linked polyvinyl alcohol biphenyl dicarboxaldehyde. S3. A methanol solution of cross-linked polyvinyl alcohol biphenyl aldehyde (PVA) with a mass fraction of 8-12% is ultrasonically dispersed at 50-80 kHz for 30-50 min, and then electrospun at room temperature with a voltage of 20-25 V, a receiving distance of 15-18 cm, a spinning rate of 0.2-0.5 mL / h, and a humidity of 20-40% to obtain a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer. S4. Hydroxypolysiloxane, tannic acid ester polymer and N,N-dimethylformyl are mixed at a mass ratio of 16:2~3:20, heated to 60~62℃, and triethylamine is added at 0.001~0.002 times the mass of hydroxypolysiloxane. The mixture is heated to 100~110℃ and reacted for 12h. The pH is neutralized to 6.8~7.2 with hydrochloric acid, washed 3~5 times with deionized water, rotary evaporated, and vacuum dried at 60~70℃ to obtain polysiloxane tannic acid ester. S5. Place the polyethylene membrane in a reaction chamber, evacuate it, and then introduce oxygen to maintain a pressure of 20-30 Pa. Perform plasma treatment with a power of 50-80 W for 2-4 min and an electrode distance of 6-10 cm to obtain a polyethylene porous membrane precursor. Mix polysiloxane tannic acid, crosslinking agent vinyltriethoxysilane, catalyst chloroplatinic acid, and toluene in a mass ratio of 8-10:1:0.01-0.03:10, and ultrasonically disperse the mixture evenly. Impregnate the polyethylene porous membrane precursor with the mixture for 1-3 min, then remove it and heat it to 80-120℃ under a nitrogen atmosphere for 30-50 min. Wash it with toluene 3-5 times and vacuum dry it at 60-70℃ to obtain a polyethylene porous membrane. S6. The polyvinyl alcohol biphenyl dimethyl ether fiber layer and the polyethylene porous membrane are placed in a hot press in sequence, heated to 120~140℃, pressure of 5~7MPa, time of 8~10min, cooled to room temperature and then peeled off to obtain an air filter membrane for medical infusion devices.

[0010] Preferably, in step S1 above, the preparation method of the end-carboxyl hyperbranched polyester is as follows: Under a nitrogen atmosphere, itaconic acid, triethanolamine, and N,N-dimethylformamide are mixed in a mass ratio of 13:36~40:80~120, heated to 120~130℃, and reacted for 4~5 hours. Then, succinic acid at 0.7~0.8 times the mass of itaconic acid is added, and the reaction continues for 4~5 hours. The mixture is then concentrated by rotary evaporation and finally dried under vacuum at 110~120℃ to obtain the end-carboxyl hyperbranched polyester.

[0011] Preferably, in step S2 above, the preparation method of mercaptoSchiff base phosphate is as follows: under a nitrogen atmosphere, vanillin and ethanol are mixed at a mass ratio of 1:5~6, and ethylenediamine at a rate of 1~3 ml / min is added dropwise at a mass ratio of 0.4~0.5 times that of vanillin. The mixture is heated to 28~32℃ and reacted for 2~3 h to obtain a vanillin solution. Phosphate acrylate, ethanol, trimethylolpropane tris(3-mercaptopropionate) and catalyst p-toluenesulfonic acid are mixed at a mass ratio of 1:1.1~1.3:6:0.02, and the mixture is heated to 58~62℃ and reacted for 4~5 h. A vanillin solution at a mass ratio of 5~7 times that of phosphate acrylate is added dropwise at a rate of 1~3 ml / min, and the mixture is heated to 78~82℃ and reacted for 7~9 h. The mixture is then distilled under reduced pressure and dried under vacuum at 40~50℃ to obtain mercaptoSchiff base phosphate.

[0012] Preferably, in step S4 above, the preparation method of hydroxyl polysiloxane is as follows: vinyltriethoxysilane, diphenyldiethoxysilane, dimethyldiethoxysilane, deionized water and acetic acid with a catalyst mass fraction of 0.2% are mixed in a mass ratio of 50:25:25:3.6~3.8:0.2, heated to 74~76℃, reacted for 4~6h, and rotary evaporated to obtain hydroxyl polysiloxane.

[0013] Preferably, in step S4 above, the preparation method of the tannic acid ester polymer is as follows: tannic acid, pyridine, and methyltetrahydrophthalic anhydride are mixed in a mass ratio of 1:10:2~2.2, heated to 30~34℃, stirred and dissolved, then heated to 88~91℃, and stirred and reacted at 400~800 rpm for 48~52 h. The mixture is washed 3~5 times with anhydrous diethyl ether, dissolved in tetrahydrofuran, precipitated with anhydrous diethyl ether, and finally dried at 40~50℃ to obtain the tannic acid ester polymer.

[0014] Preferably, in step S5 above, the method for preparing the polyethylene film is as follows: a 5-15% by mass solution of polyethylene in dichloromethane is heated to 180-220°C, completely dissolved, and then flash-spun into fibers at a pressure of 20-30 MPa and a stirring speed of 500-1500 rpm. After separation, the fibers are placed in a hot press preheated to 50-70°C, with a hot pressing pressure of 0.8-1.2 MPa and a time of 4-6 min. The fibers are then cooled to room temperature and cut to obtain the polyethylene film.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are: The air filter membrane for medical infusion devices prepared by this invention is made by combining a cross-linked polyvinyl alcohol biphenyl dimethyl ether fiber layer with a porous polyethylene membrane. The cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer is prepared by reacting biphenyl aldehyde, mercapto Schiff base phosphate, and polyvinyl alcohol, followed by reaction with modified polyethyleneimine, and then by wet spinning. Mercapto Schiff base phosphate is prepared by reacting trimethylolpropane tris(3-mercaptopropionate), phosphate acrylate, ethylenediamine, and vanillin. Modified polyethyleneimine is prepared by reacting polyethyleneimine with carboxyl-terminated hyperbranched polyester. Biphenyl aldehyde reacts with bis-mercapto Schiff base phosphate to form a stable bis-Schiff base phosphate derivative containing a biphenyl backbone, which then reacts with modified polyethyleneimine with a hyperbranched polyester structure to form a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer with both hydrophobic and antibacterial properties. When combined with a polyethylene porous membrane, it not only maintains good air permeability but also has good high-temperature dimensional stability, ensuring the stability of the air filter membrane. Polyethylene porous membranes are made by plasma treating a polyethylene membrane and then grafting polysiloxane tannins onto its surface. Polysiloxane tannins are obtained by reacting hydroxyl polysiloxanes with tannin polymers, which in turn are obtained by reacting tannic acid with methyltetrahydrophthalic anhydride. Plasma treatment allows polysiloxane tannins to be grafted onto the surface of the polyethylene membrane, further enhancing its hydrophobicity and improving its bonding strength with the cross-linked polyvinyl alcohol biphenyl dimethyl aldehyde fiber layer, thus further ensuring the stability of the air filter membrane. Detailed Implementation

[0016] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those skilled in the art.

[0017] To more clearly illustrate the method provided by the present invention, the following embodiments are provided for detailed explanation. The test methods for various indicators of the air filter membranes for medical infusion devices prepared in the embodiments and comparative examples are as follows: Efficiency: The air filter membranes for medical infusion devices prepared in the examples and comparative examples were tested for filtration efficiency in accordance with YY / T 0770.2.

[0018] Air permeability: The air permeability of the air filter membranes for medical infusion devices prepared in the examples and comparative examples was tested according to YY / T 0770.2.

[0019] High temperature stability: The air filter membranes for medical infusion devices prepared in the examples and comparative examples were tested for shrinkage rate after heating at 140°C for 20 seconds in accordance with GB / T13519.

[0020] Antibacterial properties: The air filter membranes for medical infusion devices prepared in the examples and comparative examples were subjected to bacterial retention tests in accordance with YY / T 1551.2.

[0021] Water resistance pressure: The air filter membranes for medical infusion devices prepared in the examples and comparative examples were subjected to water resistance pressure tests in accordance with YY / T0770.2. Example 1:

[0022] The method for preparing the air filter membrane for medical infusion devices in this embodiment is as follows: S1. Under a nitrogen atmosphere, itaconic acid, triethanolamine, and N,N-dimethylformamide were mixed in a mass ratio of 13:36:80, heated to 120°C, and reacted for 4 hours. Then, succinic acid at a mass ratio of 0.7 times that of itaconic acid was added, and the reaction was continued for another 4 hours. The mixture was concentrated by rotary evaporation and finally dried under vacuum at 110°C to obtain a carboxyl-terminated hyperbranched polyester. Polyethyleneimine, carboxyl-terminated hyperbranched polyester, and xylene were mixed in a mass ratio of 160:24:45, stirred evenly, and then benzyltriethylammonium chloride catalyst at a mass ratio of 0.001 times that of polyethyleneimine was added. The mixture was heated to 120°C, reacted for 8 hours, distilled under reduced pressure, washed three times with deionized water, and dried under vacuum at 60°C to obtain modified polyethyleneimine. S2. Under a nitrogen atmosphere, vanillin and ethanol were mixed at a mass ratio of 1:5. Ethylenediamine, at a rate of 1 ml / min, was added dropwise at a ratio of 0.4 times the mass of vanillin. The mixture was heated to 28°C and reacted for 2 h to obtain a vanillin solution. Phosphate acrylate, ethanol, trimethylolpropane tris(3-mercaptopropionate), and the catalyst p-toluenesulfonic acid were mixed at a mass ratio of 1:1.1:6:0.02. The mixture was heated to 58°C and reacted for 4 h. A vanillin solution, at a mass ratio of 5 times the mass of phosphate acrylate, was added dropwise at a rate of 1 ml / min. The mixture was heated to 78°C and reacted for 7 h. The mixture was then distilled under reduced pressure and dried under vacuum at 40°C to obtain a mercapto-Schiff base. Phosphate ester; Biphenyl dicarboxaldehyde, mercapto-Schiff base phosphate ester and dimethyl sulfoxide were mixed in a mass ratio of 18:45:300, the pH was adjusted to 3 with hydrochloric acid, the temperature was raised to 50°C, and the reaction was stirred at 200 rpm for 12 h. The pH was neutralized to 6 with saturated sodium bicarbonate solution, and then 8 times the mass of biphenyl dicarboxaldehyde in a polyvinyl alcohol dimethyl sulfoxide solution with a mass fraction of 8% and 0.001 times the mass of biphenyl dicarboxaldehyde in a catalyst p-toluenesulfonic acid were added. The temperature was raised to 40°C and the reaction was carried out for 1 h, then raised to 75°C and the reaction was carried out for 4 h. The mixture was precipitated with ice water, refluxed three times with anhydrous ethanol, and dried under vacuum at 60°C to obtain cross-linked polyvinyl alcohol biphenyl dicarboxaldehyde. S3. A methanol solution containing 8% (w / w) of cross-linked polyvinyl alcohol biphenyl aldehyde was ultrasonically dispersed at 50 kHz for 30 min, and then electrospun at room temperature with a voltage of 20 V, a receiving distance of 15 cm, a spinning rate of 0.2 mL / h, and a humidity of 20% to obtain a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer. S4. Vinyltriethoxysilane, diphenyldiethoxysilane, dimethyldiethoxysilane, deionized water, and acetic acid with a catalyst mass fraction of 0.2% were mixed in a mass ratio of 50:25:25:3.6:0.2, heated to 74°C, reacted for 4 hours, and then rotary evaporated to obtain hydroxyl polysiloxane; tannic acid, pyridine, and methyltetrahydrophthalic anhydride were mixed in a mass ratio of 1:10:2, heated to 30°C, stirred to dissolve, then heated to 88°C, and stirred at 400 rpm for 48 hours. The mixture was then distilled using anhydrous water. The tannin ester polymer was obtained by washing three times with diethyl ether, dissolving in tetrahydrofuran, precipitating with anhydrous diethyl ether, and finally drying at 40°C. Hydroxypolysiloxane, the tannin ester polymer, and N,N-dimethylformyl were mixed in a mass ratio of 16:2:20, heated to 60°C, and 0.001 times the mass of triethylamine of the hydroxypolysiloxane was added. The mixture was heated to 100°C and reacted for 12 hours. The pH was neutralized to 6.8 with hydrochloric acid, washed three times with deionized water, rotary evaporated, and vacuum dried at 60°C to obtain polysiloxane tannin ester. S5. A 5% (w / w) polyethylene solution in dichloromethane is heated to 180°C until completely dissolved. After complete dissolution, flash spinning is performed at a pressure of 20 MPa and a stirring speed of 500 rpm. The resulting fibers are then placed in a hot press preheated to 50°C at a pressure of 0.8 MPa for 4 minutes. The fibers are cooled to room temperature and cut to obtain a polyethylene film with a thickness of 0.08 mm. The polyethylene film is then placed in a reaction chamber, evacuated, and oxygen is introduced to maintain a pressure of 20 Pa for plasma treatment. A polyethylene porous membrane precursor was prepared by using a power of 50W, a time of 2min, and an electrode distance of 6cm. Polysiloxane tannic acid, crosslinking agent vinyltriethoxysilane, catalyst chloroplatinic acid, and toluene were mixed in a mass ratio of 10:1:0.01:10, ultrasonically dispersed, and impregnated with the polyethylene porous membrane precursor. After 1min, the mixture was removed, heated to 80℃ under a nitrogen atmosphere, heat-treated for 30min, washed three times with toluene, and vacuum dried at 60℃ to obtain the polyethylene porous membrane. S6. The polyvinyl alcohol biphenyl dimethyl ether fiber layer and the polyethylene porous membrane are placed in a hot press, heated to 120°C, pressure of 5MPa, time of 8min, cooled to room temperature and then peeled off to obtain an air filter membrane for medical infusion devices with a thickness of 0.1mm. Example 2:

[0023] The method for preparing the air filter membrane for medical infusion devices in this embodiment is as follows: S1. Under a nitrogen atmosphere, itaconic acid, triethanolamine, and N,N-dimethylformamide were mixed in a mass ratio of 13:38:100, heated to 125°C, and reacted for 4.5 h. Then, succinic acid at a mass ratio of 0.75 times that of itaconic acid was added, and the reaction was continued for another 4.5 h. The mixture was concentrated by rotary evaporation and finally dried under vacuum at 115°C to obtain a carboxyl-terminated hyperbranched polyester. Polyethyleneimine, carboxyl-terminated hyperbranched polyester, and xylene were mixed in a mass ratio of 170:24:45, stirred evenly, and then benzyltriethylammonium chloride catalyst at a mass ratio of 0.005 times that of polyethyleneimine was added. The mixture was heated to 125°C, reacted for 9 h, distilled under reduced pressure, washed four times with deionized water, and dried under vacuum at 65°C to obtain modified polyethyleneimine. S2. Under a nitrogen atmosphere, vanillin and ethanol were mixed at a mass ratio of 1:5.5. Ethylenediamine, at a rate of 2 ml / min, was added dropwise at a ratio of 0.45 times the mass of vanillin. The mixture was heated to 30°C and reacted for 2.5 h to obtain a vanillin solution. Phosphate acrylate, ethanol, trimethylolpropane tris(3-mercaptopropionate), and the catalyst p-toluenesulfonic acid were mixed at a mass ratio of 1:1.2:6:0.02. The mixture was heated to 60°C and reacted for 4.5 h. A vanillin solution, at a mass ratio of 6 times the mass of phosphate acrylate, was added dropwise at a rate of 2 ml / min. The mixture was heated to 80°C and reacted for 8 h. The mixture was then distilled under reduced pressure and dried under vacuum at 45°C to obtain a mercapto-Schiff base. Phosphate ester; Biphenyl dicarboxaldehyde, mercapto-Schiff base phosphate ester and dimethyl sulfoxide were mixed in a mass ratio of 20:45:300, the pH was adjusted to 3.5 with hydrochloric acid, the temperature was raised to 51℃, and the reaction was stirred at 300 rpm for 13 h. The pH was neutralized to 6.5 with saturated sodium bicarbonate solution, and then a 9% polyvinyl alcohol dimethyl sulfoxide solution (9 times the mass of biphenyl dicarboxaldehyde) and a 0.0015 times the mass of biphenyl dicarboxaldehyde catalyst (p-toluenesulfonic acid) were added. The temperature was raised to 45℃ and the reaction was carried out for 1.5 h, then raised to 76℃ and the reaction was carried out for 5 h. The mixture was precipitated with ice water, refluxed with anhydrous ethanol four times, and dried under vacuum at 65℃ to obtain cross-linked polyvinyl alcohol biphenyl dicarboxaldehyde. S3. A methanol solution of 10% by mass of cross-linked polyvinyl alcohol biphenyl aldehyde was ultrasonically dispersed at 70 kHz for 40 min, and then electrospun at room temperature with a voltage of 23 V, a receiving distance of 16 cm, a spinning rate of 0.4 mL / h, and a humidity of 30% to obtain a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer. S4. Vinyltriethoxysilane, diphenyldiethoxysilane, dimethyldiethoxysilane, deionized water, and acetic acid with a catalyst mass fraction of 0.2% were mixed in a mass ratio of 50:25:25:3.7:0.2, heated to 75°C, and reacted for 5 hours. The mixture was then rotary evaporated to obtain hydroxyl polysiloxane. Tannic acid, pyridine, and methyltetrahydrophthalic anhydride were mixed in a mass ratio of 1:10:2.1, heated to 32°C, and stirred until dissolved. The mixture was then heated to 89°C and stirred at 600 rpm for 50 hours. The resulting product was then distilled using anhydrous water. The tannin ester polymer was obtained by washing the product four times with diethyl ether, dissolving it in tetrahydrofuran, precipitating it with anhydrous diethyl ether, and finally drying it at 45°C. Hydroxypolysiloxane, the tannin ester polymer, and N,N-dimethylformyl were mixed in a mass ratio of 16:2.5:20, heated to 61°C, and 0.0015 times the mass of triethylamine of the hydroxypolysiloxane was added. The mixture was then heated to 105°C and reacted for 12 hours. The pH was neutralized to 7.0 with hydrochloric acid, washed four times with deionized water, rotary evaporated, and vacuum dried at 65°C to obtain polysiloxane tannin ester. S5. A 10% (w / w) polyethylene solution in dichloromethane was heated to 1200℃ and completely dissolved. After dissolution, flash spinning was performed at a pressure of 25 MPa and a stirring speed of 1000 rpm. The filaments were then separated and placed in a hot press preheated to 60℃ at a pressure of 1.0 MPa for 5 minutes. The filaments were cooled to room temperature and cut to obtain a polyethylene film with a thickness of 0.14 mm. The polyethylene film was placed in a reaction chamber, evacuated, and oxygen was introduced to maintain a pressure of 25 Pa for plasma reaction. A polyethylene porous membrane precursor was prepared by processing at a power of 60W for 3 minutes with an electrode distance of 8cm. Polysiloxane tannic acid ester, crosslinking agent vinyltriethoxysilane, catalyst chloroplatinic acid and toluene were mixed at a mass ratio of 9:1:0.02:10, ultrasonically dispersed, and impregnated with the polyethylene porous membrane precursor. After 2 minutes, the mixture was removed, heated to 100℃ under a nitrogen atmosphere, heat-treated for 40 minutes, washed 4 times with toluene, and vacuum dried at 64℃ to obtain the polyethylene porous membrane. S6. The polyvinyl alcohol biphenyl dimethyl ether fiber layer and the polyethylene porous membrane are placed in a hot press, heated to 130°C, pressure of 6MPa, time of 9min, cooled to room temperature and then peeled off to obtain an air filter membrane for medical infusion devices with a thickness of 0.25mm. Example 3:

[0024] The method for preparing the air filter membrane for medical infusion devices in this embodiment is as follows: S1. Under a nitrogen atmosphere, itaconic acid, triethanolamine, and N,N-dimethylformamide were mixed in a mass ratio of 13:40:120, heated to 130°C, and reacted for 5 hours. Then, succinic acid at a mass ratio of 0.8 times that of itaconic acid was added, and the reaction was continued for another 5 hours. The mixture was concentrated by rotary evaporation and finally dried under vacuum at 120°C to obtain a carboxyl-terminated hyperbranched polyester. Polyethyleneimine, carboxyl-terminated hyperbranched polyester, and xylene were mixed in a mass ratio of 180:24:45, stirred evenly, and then benzyltriethylammonium chloride catalyst at a mass ratio of 0.002 times that of polyethyleneimine was added. The mixture was heated to 130°C, reacted for 10 hours, distilled under reduced pressure, washed 5 times with deionized water, and dried under vacuum at 70°C to obtain modified polyethyleneimine. S2. Under a nitrogen atmosphere, vanillin and ethanol were mixed at a mass ratio of 1:6, and ethylenediamine (0.5 times the mass of vanillin) was added dropwise at a rate of 3 ml / min. The mixture was heated to 32 °C and reacted for 3 h to obtain a vanillin solution. Phosphate acrylate, ethanol, trimethylolpropane tris(3-mercaptopropionate), and p-toluenesulfonic acid catalyst were mixed at a mass ratio of 1:1.3:6:0.02, heated to 62 °C, and reacted for 5 h. A vanillin solution (7 times the mass of phosphate acrylate) was added dropwise at a rate of 3 ml / min, and the mixture was heated to 82 °C and reacted for 9 h. The mixture was then distilled under reduced pressure and dried under vacuum at 50 °C to obtain mercapto-Schiff base phosphorus. Acid ester; Biphenyl dicarboxaldehyde, mercapto-Schiff base phosphate and dimethyl sulfoxide were mixed in a mass ratio of 22:45:300, the pH was adjusted to 4 with hydrochloric acid, the temperature was raised to 52°C, and the reaction was stirred at 400 rpm for 14 h. The pH was neutralized to 7 with saturated sodium bicarbonate solution, and then 10 times the mass of biphenyl dicarboxaldehyde in a 10% polyvinyl alcohol dimethyl sulfoxide solution and 0.002 times the mass of biphenyl dicarboxaldehyde in a catalyst p-toluenesulfonic acid were added. The temperature was raised to 50°C and the reaction was carried out for 2 h, then raised to 78°C and the reaction was carried out for 6 h. The mixture was precipitated with ice water, quenched five times with anhydrous ethanol, and dried under vacuum at 70°C to obtain cross-linked polyvinyl alcohol biphenyl dicarboxaldehyde. S3. A methanol solution of 12% by mass of cross-linked polyvinyl alcohol biphenyl aldehyde was ultrasonically dispersed at 80 kHz for 50 min, and then electrospun at room temperature with a voltage of 25 V, a receiving distance of 18 cm, a spinning rate of 0.5 mL / h, and a humidity of 40% to obtain a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer. S4. Vinyltriethoxysilane, diphenyldiethoxysilane, dimethyldiethoxysilane, deionized water, and acetic acid with a catalyst mass fraction of 0.2% were mixed in a mass ratio of 50:25:25:3.8:0.2, heated to 76°C, and reacted for 6 hours. The mixture was then rotary evaporated to obtain hydroxyl polysiloxane. Tannic acid, pyridine, and methyltetrahydrophthalic anhydride were mixed in a mass ratio of 1:10:2.2, heated to 34°C, and stirred until dissolved. The mixture was then heated to 91°C and stirred at 800 rpm for 52 hours. The reaction was then carried out using a non-acidic acid solution. The tannin ester polymer was obtained by washing five times with aqueous ether, dissolving in tetrahydrofuran, precipitating with anhydrous ether, and finally drying at 50°C. Hydroxypolysiloxane, the tannin ester polymer, and N,N-dimethylformyl were mixed in a mass ratio of 16:3:20, heated to 62°C, and 0.002 times the mass of triethylamine of the hydroxypolysiloxane was added. The mixture was then heated to 110°C and reacted for 12 hours. The pH was neutralized to 7.2 with hydrochloric acid, washed five times with deionized water, rotary evaporated, and vacuum dried at 70°C to obtain polysiloxane tannin ester. S5. A 15% (w / w) polyethylene solution in dichloromethane was heated to 220°C until completely dissolved. After dissolution, the solution was flash-spun into fibers at a pressure of 30 MPa and a stirring speed of 1500 rpm. The fibers were then separated and placed in a hot press preheated to 70°C at a pressure of 1.2 MPa for 6 minutes. After cooling to room temperature, the fibers were cut to obtain a polyethylene film with a thickness of 0.22 mm. The polyethylene film was then placed in a reaction chamber, evacuated, and oxygen was introduced to maintain a pressure of 30 Pa for plasma treatment. A polyethylene porous membrane precursor was prepared by using an electrode distance of 10 cm and a power of 80 W for 4 min. Polysiloxane tannic acid, crosslinking agent vinyltriethoxysilane, catalyst chloroplatinic acid and toluene were mixed in a mass ratio of 10:1:0.03:10 and ultrasonically dispersed evenly. The mixture was then impregnated with the polyethylene porous membrane precursor for 3 min and removed. The mixture was then heated to 120 °C and heat-treated for 50 min under a nitrogen atmosphere. The mixture was washed 5 times with toluene and vacuum dried at 70 °C to obtain the polyethylene porous membrane. S6. The polyvinyl alcohol biphenyl dimethyl ether fiber layer and the polyethylene porous membrane are placed in a hot press, heated to 140°C, pressure of 7MPa, time of 10min, cooled to room temperature and then peeled off to obtain an air filter membrane for medical infusion devices with a thickness of 0.33mm.

[0025] Comparative Example 1 The preparation method of Comparative Example 1 is the same as that of Example 2. The difference between this air filter membrane for medical infusion devices and Example 2 is that the cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer is prepared by reacting biphenyl aldehyde and polyvinyl alcohol, then reacting with modified polyethyleneimine, and finally wet spinning.

[0026] Comparative Example 2 The preparation method of Comparative Example 2 is the same as that of Example 2. The difference between this air filter membrane for medical infusion devices and Example 2 is that the cross-linked polyvinyl alcohol biphenyl dicarbonate fiber layer is prepared by wet spinning after reacting biphenyl dicarbonate, mercapto-Schiff base phosphate and polyvinyl alcohol.

[0027] Comparative Example 3 The preparation method of Comparative Example 3 is the same as that of Example 2. The difference between this air filter membrane for medical infusion devices and Example 2 is that the air filter membrane for medical infusion devices is made by combining a polyvinyl alcohol biphenyl aldehyde fiber layer with a polyethylene porous membrane; the polyvinyl alcohol biphenyl aldehyde fiber layer is made by wet spinning after the reaction of biphenyl aldehyde and polyvinyl alcohol.

[0028] Comparative Example 4 The preparation method of Comparative Example 4 is the same as that of Example 2. The difference between this air filter membrane for medical infusion devices and Example 2 is that the polyethylene porous membrane is prepared by plasma treatment of polyethylene membrane.

[0029] Comparative Example 5 The preparation method of Comparative Example 5 is the same as that of Example 2. The difference between this air filter membrane for medical infusion devices and Example 2 is that the polyethylene porous membrane is prepared by plasma treatment of polyethylene membrane followed by grafting hydroxyl polysiloxane onto its surface.

[0030] Example of effect Table 1 below shows the performance analysis results of the air filter membranes for medical infusion devices prepared using Examples 1 to 3 and Comparative Examples 1 to 5 of the present invention: Table 1 efficiency(%) Air permeability (L / min) Shrinkage rate (%) Retention rate (%) Water pressure at which water is blocked (kPa) Example 1 99.96 6.4 2.1 99.9 22 Example 2 99.97 6.5 1.7 99.9 25 Example 3 99.97 6.2 2.4 99.9 23 Comparative Example 1 94.97 5.5 5.8 99.9 17 Comparative Example 2 91.97 5.3 5.9 99.9 16 Comparative Example 3 99.97 5.9 6.2 99.9 14 Comparative Example 4 99.97 5.9 2.6 91.6 19 Comparative Example 5 99.97 5.8 3.0 90.5 17 By comparing the experimental data of the examples and comparative examples in Table 1, it can be clearly found that the air filter membranes for medical infusion devices prepared using Examples 1, 2, and 3 have superior efficiency, air permeability, and stability.

[0031] A comparison of the experimental data from Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 reveals that biphenyl dicarboxaldehyde reacts with dithiol Schiff base phosphate to form a stable dithiol base phosphate derivative containing a biphenyl backbone. This derivative then reacts with modified polyethyleneimine, which has a hyperbranched polyester structure, to form a cross-linked polyvinyl alcohol biphenyl dicarboxaldehyde fiber layer that combines hydrophobicity and antibacterial properties. When this layer is combined with a porous polyethylene membrane, it not only maintains good air permeability but also exhibits good high-temperature dimensional stability, ensuring the stability of the air filter membrane.

[0032] A comparison of the experimental data from Examples 1, 2, 3 and Comparative Examples 4 and 5 reveals that the polyethylene membrane treated with plasma can graft polysiloxane tannins onto its surface, further enhancing its hydrophobicity and improving its bonding strength with the cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer, thus further ensuring the stability of the air filter membrane.

[0033] Obviously, the above embodiments are merely examples to clearly illustrate the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, these obvious variations or modifications derived from the spirit of the present invention are still within the protection scope of the present invention.

Claims

1. An air filter membrane for medical infusion devices, characterized in that it is The cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer is prepared by compositing a polyethylene porous membrane with a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer. The cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer is prepared by reacting biphenyl aldehyde, mercapto-Schiff base phosphate and polyvinyl alcohol, and then reacting with modified polyethyleneimine, followed by wet spinning. The polyethylene porous membrane is prepared by plasma treating a polyethylene membrane and then grafting polysiloxane tannin onto its surface.

2. The air filter membrane for medical infusion devices according to claim 1, characterized in that, The mercapto-Schiff base phosphate ester is prepared by reacting trimethylolpropane tris(3-mercaptopropionate), phosphate acrylate, ethylenediamine, and vanillin; the modified polyethyleneimine is prepared by reacting polyethyleneimine with carboxyl-terminated hyperbranched polyester.

3. The air filter membrane for medical infusion devices according to claim 1, characterized in that, The polysiloxane tannic acid ester is prepared by reacting hydroxyl polysiloxane with a tannic acid ester polymer; the tannic acid ester polymer is prepared by reacting tannic acid with methyltetrahydrophthalic anhydride.

4. The air filter membrane for medical infusion devices according to claim 1, characterized in that, The plasma treatment is an oxygen plasma treatment.

5. The method for preparing an air filter membrane for medical infusion devices according to claim 1, characterized in that, The specific steps include the following: S1. Polyethyleneimine, carboxyl-terminated hyperbranched polyester, and xylene are mixed in a mass ratio of 160-180:24:

45. After stirring evenly, benzyltriethylammonium chloride catalyst (0.001-0.002 times the mass of polyethyleneimine) is added. The mixture is heated to 120-130℃ and reacted for 8-10 hours. The mixture is then distilled under reduced pressure, washed 3-5 times with deionized water, and dried under vacuum at 60-70℃ to obtain modified polyethyleneimine. S2. Biphenyl dicarboxaldehyde, mercapto-Schiff base phosphate, and dimethyl sulfoxide are mixed in a mass ratio of 18-22:45:

300. The pH is adjusted to 3-4 with hydrochloric acid, and the temperature is raised to 50-52°C. The mixture is stirred at 200-400 rpm for 12-14 hours. The pH is neutralized to 6-7 with saturated sodium bicarbonate solution. Then, 8-10 times the mass of biphenyl dicarboxaldehyde in a polyvinyl alcohol dimethyl sulfoxide solution with a mass fraction of 8-10% and 0.001-0.002 times the mass of biphenyl dicarboxaldehyde in a catalyst p-toluenesulfonic acid are added. The temperature is raised to 40-50°C and the reaction is carried out for 1-2 hours. The temperature is raised to 75-78°C and the reaction is carried out for 4-6 hours. The mixture is precipitated with ice water and anhydrous ethanol 3-5 times. The mixture is then dried under vacuum at 60-70°C to obtain cross-linked polyvinyl alcohol biphenyl dicarboxaldehyde. S3. A methanol solution of cross-linked polyvinyl alcohol biphenyl aldehyde (PVA) with a mass fraction of 8-12% is ultrasonically dispersed at 50-80 kHz for 30-50 min, and then electrospun at room temperature with a voltage of 20-25 V, a receiving distance of 15-18 cm, a spinning rate of 0.2-0.5 mL / h, and a humidity of 20-40% to obtain a cross-linked polyvinyl alcohol biphenyl aldehyde fiber layer. S4. Hydroxypolysiloxane, tannic acid ester polymer and N,N-dimethylformyl are mixed at a mass ratio of 16:2~3:20, heated to 60~62℃, and triethylamine is added at 0.001~0.002 times the mass of hydroxypolysiloxane. The mixture is heated to 100~110℃ and reacted for 12h. The pH is neutralized to 6.8~7.2 with hydrochloric acid, washed 3~5 times with deionized water, rotary evaporated, and vacuum dried at 60~70℃ to obtain polysiloxane tannic acid ester. S5. Place the polyethylene membrane in a reaction chamber, evacuate it, and then introduce oxygen to maintain a pressure of 20-30 Pa. Perform plasma treatment with a power of 50-80 W for 2-4 min and an electrode distance of 6-10 cm to obtain a polyethylene porous membrane precursor. Mix polysiloxane tannic acid, crosslinking agent vinyltriethoxysilane, catalyst chloroplatinic acid, and toluene in a mass ratio of 8-10:1:0.01-0.03:10, and ultrasonically disperse the mixture evenly. Impregnate the polyethylene porous membrane precursor with the mixture for 1-3 min, then remove it and heat it to 80-120℃ under a nitrogen atmosphere for 30-50 min. Wash it with toluene 3-5 times and vacuum dry it at 60-70℃ to obtain a polyethylene porous membrane. S6. The polyvinyl alcohol biphenyl dimethyl ether fiber layer and the polyethylene porous membrane are placed in a hot press in sequence, heated to 120~140℃, pressure of 5~7MPa, time of 8~10min, cooled to room temperature and then peeled off to obtain an air filter membrane for medical infusion equipment with a thickness of 0.1~0.33mm.

6. The method for preparing an air filter membrane for medical infusion devices according to claim 5, characterized in that, In step S1 above, the preparation method of carboxyl-terminated hyperbranched polyester is as follows: under a nitrogen atmosphere, itaconic acid, triethanolamine and N,N-dimethylformamide are mixed in a mass ratio of 13:36~40:80~120, heated to 120~130℃, and reacted for 4~5 hours. Then, succinic acid with a mass of 0.7~0.8 times that of itaconic acid is added, and the reaction continues for 4~5 hours. The mixture is concentrated by rotary evaporation and finally dried under vacuum at 110~120℃ to obtain carboxyl-terminated hyperbranched polyester.

7. The method for preparing an air filter membrane for medical infusion devices according to claim 5, characterized in that, In step S2 above, the preparation method of mercaptoSchiff base phosphate is as follows: under a nitrogen atmosphere, vanillin and ethanol are mixed at a mass ratio of 1:5~6, and ethylenediamine at a rate of 1~3 ml / min is added dropwise at a mass ratio of 0.4~0.5 times that of vanillin. The temperature is raised to 28~32℃, and the reaction is carried out for 2~3 h to obtain a vanillin solution. Phosphate acrylate, ethanol, trimethylolpropane tris(3-mercaptopropionate) and catalyst p-toluenesulfonic acid are mixed at a mass ratio of 1:1.1~1.3:6:0.02, and the temperature is raised to 58~62℃. The reaction is carried out for 4~5 h, and vanillin solution at a rate of 1~3 ml / min at a mass ratio of 5~7 times that of phosphate acrylate is added dropwise. The temperature is raised to 78~82℃, and the reaction is carried out for 7~9 h. The mixture is then distilled under reduced pressure and dried under vacuum at 40~50℃ to obtain mercaptoSchiff base phosphate.

8. The method for preparing an air filter membrane for medical infusion devices according to claim 5, characterized in that, In step S4 above, the preparation method of hydroxyl polysiloxane is as follows: vinyltriethoxysilane, diphenyldiethoxysilane, dimethyldiethoxysilane, deionized water and acetic acid with a catalyst mass fraction of 0.2% are mixed in a mass ratio of 50:25:25:3.6~3.8:0.2, heated to 74~76℃, reacted for 4~6h, and then rotary evaporated to obtain hydroxyl polysiloxane.

9. The method for preparing an air filter membrane for medical infusion devices according to claim 5, characterized in that, In step S4 above, the preparation method of the tannic acid ester polymer is as follows: tannic acid, pyridine, and methyltetrahydrophthalic anhydride are mixed in a mass ratio of 1:10:2~2.2, heated to 30~34℃, stirred and dissolved, then heated to 88~91℃, and stirred and reacted at 400~800 rpm for 48~52 h. The mixture is washed 3~5 times with anhydrous diethyl ether, dissolved in tetrahydrofuran, precipitated with anhydrous diethyl ether, and finally dried at 40~50℃ to obtain the tannic acid ester polymer.

10. The method for preparing an air filter membrane for medical infusion devices according to claim 1, characterized in that, In step S5 above, the polyethylene film is prepared as follows: a 5-15% (w / w) polyethylene solution in dichloromethane is heated to 180-220°C and completely dissolved. Then, it is flash-spun into fibers at a pressure of 20-30 MPa and a stirring speed of 500-1500 rpm. After fiber separation, the fibers are placed in a hot press preheated to 50-70°C at a pressing pressure of 0.8-1.2 MPa for 4-6 minutes. The fibers are then cooled to room temperature and cut to obtain a polyethylene film with a thickness of 0.08-0.22 mm.