Polytetrafluoroethylene membrane for air filtration and preparation method thereof

Abstract

The invention discloses a polytetrafluoroethylene membrane for air filtration and a preparation method thereof, and relates to the technical field of polytetrafluoroethylene membranes. The polytetrafluoroethylene film is prepared from polytetrafluoroethylene resin and isododecane. Then the polytetrafluoroethylene membrane is subjected to amination treatment, so that active sites on the surface of the polytetrafluoroethylene membrane are increased, and more dendrobium polysaccharide-hyaluronic acid components can be loaded. The surface of the aminated polytetrafluoroethylene film is coated with a layer of dendrobium polysaccharide-hyaluronic acid mixed liquid, dendrobium polysaccharide has a good bacteriostatic effect on staphylococcus aureus and escherichia coli, and the antibacterial performance of the polytetrafluoroethylene film can be improved. In addition, copper chloride is added into the dendrobium polysaccharide-hyaluronic acid mixed solution, and the copper chloride can destroy microbial cell membranes, so that the antibacterial effect is achieved, and the antibacterial performance of the polytetrafluoroethylene membrane is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polytetrafluoroethylene membranes, in particular to a polytetrafluoroethylene membrane for air filtration and a preparation method thereof. Background Art

[0002] With the acceleration of industrialization and urbanization, the increase of harmful substances in the air has posed a serious threat to human health. Although traditional air filter materials have achieved certain results in removing particulate matter and harmful gases, they are insufficient in antibacterial performance and durability. This makes the demand for new filter materials more urgent.

[0003] Polytetrafluoroethylene is widely used in the field of air filtration due to its excellent chemical stability and anti-pollution ability. However, the polytetrafluoroethylene membrane itself lacks antibacterial properties and cannot effectively inhibit the growth of microorganisms in the air. Therefore, developing a polytetrafluoroethylene membrane with antibacterial properties can not only improve the efficiency of air filtration, but also provide people with a healthier living environment. This innovation has broad application prospects in air purification, air conditioning systems and other related fields.

[0004] In order to solve the above problems and improve the antibacterial performance of the polytetrafluoroethylene membrane, the present invention provides a polytetrafluoroethylene membrane for air filtration and a preparation method thereof. Summary of the invention

[0005] The object of the present invention is to provide a polytetrafluoroethylene membrane for air filtration and a preparation method thereof, so as to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a polytetrafluoroethylene membrane for air filtration comprises the following steps: Step 1: Take polytetrafluoroethylene resin and isododecane, mix them evenly, mature them, extrude, calender, and dry them to obtain a polytetrafluoroethylene tape, stretch them, and heat-set them to obtain a polytetrafluoroethylene film; Step 2: Soak the polytetrafluoroethylene membrane in an ethanol and deionized water solution for 15-20 minutes, wash it with deionized water, and then soak the treated polytetrafluoroethylene membrane in a 1,3-diaminopropane solution for 1.5-2 hours, wash it with deionized water, and dry it to obtain an amino polytetrafluoroethylene membrane; Step 3: coating the mixed solution of dendrobium polysaccharide and hyaluronic acid on the surface of the amino polytetrafluoroethylene membrane and drying it to obtain the polytetrafluoroethylene membrane for air filtration.

[0007] More optimally, the preparation method of the Dendrobium polysaccharide-hyaluronic acid mixed solution is: take Dendrobium polysaccharide and ethyl acetate, ultrasonically disperse them to obtain Dendrobium polysaccharide solution; take modified hyaluronic acid and phosphate buffer, stir them evenly, add Dendrobium polysaccharide solution, ultrasonically treat for 20-30 minutes, add copper chloride, stir for 3-4 hours, and obtain Dendrobium polysaccharide-hyaluronic acid mixed solution.

[0008] Preferably, the preparation method of the modified hyaluronic acid comprises the following steps: S1: Take folic acid and dimethyl sulfoxide, stir evenly, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, stir for 60-70 minutes to obtain a mixed solution A; take amino hyaluronic acid and phosphate buffer, stir evenly, add them dropwise to the mixed solution A, stir for 22-26 hours, dialyze, and freeze-dry to obtain a mixture A; S2: Take thioglycolic acid and phosphate buffer, stir evenly, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, stir evenly to obtain a mixed solution B; take mixture A and phosphate buffer, stir evenly, add mixed solution B dropwise, stir for 22-26 hours, dialyze, and lyophilize to obtain modified hyaluronic acid.

[0009] More optimally, in S1, the preparation method of amino hyaluronic acid is: take hyaluronic acid and deionized water, stir evenly, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, stir evenly, add cystamine dihydrochloride, stir for 5-7h, dialyze, and freeze-dry to obtain amino hyaluronic acid.

[0010] More optimally, the polytetrafluoroethylene membrane comprises the following components, by weight: 100-110 parts of polytetrafluoroethylene resin and 28-32 parts of isododecane.

[0011] More optimally, in step three, the coating thickness of the Dendrobium polysaccharide-hyaluronic acid mixture is 1-1.5µm.

[0012] More optimally, the particle size of the Dendrobium polysaccharide is 80 mesh-120 mesh.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses polytetrafluoroethylene resin and isomeric dodecane to prepare a polytetrafluoroethylene membrane, and then performs an amination treatment on the polytetrafluoroethylene membrane to increase the active sites on the surface of the polytetrafluoroethylene membrane, so that more dendrobium polysaccharide-hyaluronic acid components can be loaded.

[0014] 2. The present invention coats a layer of dendrobium polysaccharide-hyaluronic acid mixed solution on the surface of the amino polytetrafluoroethylene film. Dendrobium polysaccharide has a good antibacterial effect on Staphylococcus aureus and Escherichia coli, and can improve the antibacterial properties of the polytetrafluoroethylene film. Hyaluronic acid is modified and then dendrobium polysaccharide is compounded with it, which can achieve a good sustained release effect, enhance antibacterial properties, reduce the attachment and reproduction of microorganisms on the film surface, and further improve air quality. The present invention also adds copper chloride to the dendrobium polysaccharide-hyaluronic acid mixed solution. Copper chloride can destroy the microbial cell membrane, thereby achieving an antibacterial effect and improving the antibacterial properties of the polytetrafluoroethylene film. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] There is no particular restriction on the sources and purchase channels of the raw materials involved in the present invention, and illustratively include: polytetrafluoroethylene resin: can be purchased from DuPont, model: 601A; isododecane: can be purchased from ExxonMobil, model: ISOPAR-H; hyaluronic acid: can be purchased from Shandong Freda Biological Co., Ltd., relative molecular mass: 20-40Da; Dendrobium polysaccharide: can be purchased from Shaanxi Lvlai Biotechnology Co., Ltd., particle size: 80 mesh-120 mesh.

[0017] Embodiment 1: A method for preparing a polytetrafluoroethylene membrane for air filtration, comprising the following steps: Step 1: Preparation of polytetrafluoroethylene membrane: Take polytetrafluoroethylene resin and isododecane, mix them evenly, mature them, extrude, calender, and dry them to obtain polytetrafluoroethylene tape, stretch them, and heat-set them to obtain polytetrafluoroethylene film; The polytetrafluoroethylene membrane comprises the following components, by weight: 105 parts of polytetrafluoroethylene resin, 30 parts of isomeric dodecane; Step 2: Preparation of amino polytetrafluoroethylene membrane: The polytetrafluoroethylene membrane was immersed in an ethanol-deionized water solution with a volume ratio of 1:1 for 18 minutes, and then washed with deionized water. Then, the treated polytetrafluoroethylene membrane was immersed in a 1,3-diaminopropane solution with a concentration of 1 mg / mL for 1.7 hours, and then washed with deionized water and dried to obtain an amino polytetrafluoroethylene membrane; Step 3: Preparation of amino hyaluronic acid: Take 1 g of hyaluronic acid and 100 mL of deionized water, stir evenly, add 1 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.2 g of N-hydroxysuccinimide, stir evenly, add 3 g of cystamine dihydrochloride, stir for 6 h, dialyze, and freeze-dry to obtain amino hyaluronic acid; Step 4: Preparation of modified hyaluronic acid: Take 0.1 g of folic acid and 100 mL of dimethyl sulfoxide, stir evenly, add 0.05 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.1 g of N-hydroxysuccinimide, stir for 65 min to obtain a mixed solution A; take 1 g of amino hyaluronic acid and 50 mL of phosphate buffer with a pH value of 7.4, stir evenly, add them dropwise to the mixed solution A, stir for 24 h, dialyze, and lyophilize to obtain a mixture A; Take 0.1 g of thioglycolic acid and 10 mL of phosphate buffer with a pH value of 7.4, stir evenly, add 0.4 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.25 g of N-hydroxysuccinimide, stir evenly, and obtain a mixed solution B; take 0.2 g of mixture A and 20 mL of phosphate buffer with a pH value of 7.4, stir evenly, add the mixed solution B dropwise, stir for 24 hours, dialyze, and freeze-dry to obtain modified hyaluronic acid; Step 5: Preparation of Dendrobium polysaccharide-hyaluronic acid mixed solution: Take 0.1g of dendrobium polysaccharide and 20mL of ethyl acetate, and disperse them by ultrasonication to obtain a dendrobium polysaccharide solution; take 1g of modified hyaluronic acid and 100mL of phosphate buffer with a pH value of 7.4, stir evenly, add the dendrobium polysaccharide solution, ultrasonicate for 25min, add 0.1g of copper chloride, and stir for 3.5h to obtain a dendrobium polysaccharide-hyaluronic acid mixed solution; Step 6: Preparation of polytetrafluoroethylene membrane for air filtration: The Dendrobium polysaccharide-hyaluronic acid mixed solution was coated on the surface of a 250µm thick amino polytetrafluoroethylene membrane with a coating thickness of 1µm, and then dried to obtain a polytetrafluoroethylene membrane for air filtration.

[0018] Embodiment 2: A method for preparing a polytetrafluoroethylene membrane for air filtration, comprising the following steps: Step 1: Preparation of polytetrafluoroethylene membrane: Take polytetrafluoroethylene resin and isododecane, mix them evenly, mature them, extrude, calender, and dry them to obtain polytetrafluoroethylene tape, stretch them, and heat-set them to obtain polytetrafluoroethylene film; The polytetrafluoroethylene film comprises the following components, by weight: 100 parts of polytetrafluoroethylene resin, 28 parts of isomeric dodecane; Step 2: Preparation of amino polytetrafluoroethylene membrane: The polytetrafluoroethylene membrane was immersed in an ethanol-deionized water solution with a volume ratio of 1:1 for 15 minutes, and then washed with deionized water. Then, the treated polytetrafluoroethylene membrane was immersed in a 1,3-diaminopropane solution with a concentration of 1 mg / mL for 1.5 hours, and then washed with deionized water and dried to obtain an amino polytetrafluoroethylene membrane; Step 3: Preparation of amino hyaluronic acid: Take 1 g of hyaluronic acid and 100 mL of deionized water, stir evenly, add 1 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.2 g of N-hydroxysuccinimide, stir evenly, add 3 g of cystamine dihydrochloride, stir for 5 h, dialyze, and freeze-dry to obtain amino hyaluronic acid; Step 4: Preparation of modified hyaluronic acid: Take 0.1 g of folic acid and 100 mL of dimethyl sulfoxide, stir evenly, add 0.05 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.1 g of N-hydroxysuccinimide, stir for 60 min to obtain a mixed solution A; take 1 g of amino hyaluronic acid and 50 mL of phosphate buffer with a pH value of 7.4, stir evenly, add them dropwise to the mixed solution A, stir for 22 h, dialyze, and lyophilize to obtain a mixture A; Take 0.1 g of thioglycolic acid and 10 mL of phosphate buffer with a pH value of 7.4, stir evenly, add 0.4 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.25 g of N-hydroxysuccinimide, stir evenly to obtain a mixed solution B; take 0.2 g of mixture A and 20 mL of phosphate buffer with a pH value of 7.4, stir evenly, add the mixed solution B dropwise, stir for 22 hours, dialyze, and freeze-dry to obtain modified hyaluronic acid; Step 5: Preparation of Dendrobium polysaccharide-hyaluronic acid mixed solution: Take 0.1g of dendrobium polysaccharide and 20mL of ethyl acetate, and disperse them by ultrasonication to obtain a dendrobium polysaccharide solution; take 1g of modified hyaluronic acid and 100mL of phosphate buffer with a pH value of 7.4, stir evenly, add the dendrobium polysaccharide solution, ultrasonically treat for 20min, add 0.1g of copper chloride, and stir for 3h to obtain a dendrobium polysaccharide-hyaluronic acid mixed solution; Step 6: Preparation of polytetrafluoroethylene membrane for air filtration: The Dendrobium polysaccharide-hyaluronic acid mixed solution was coated on the surface of a 250µm thick amino polytetrafluoroethylene membrane with a coating thickness of 1µm, and then dried to obtain a polytetrafluoroethylene membrane for air filtration.

[0019] Embodiment 3: A method for preparing a polytetrafluoroethylene membrane for air filtration, comprising the following steps: Step 1: Preparation of polytetrafluoroethylene membrane: Take polytetrafluoroethylene resin and isododecane, mix them evenly, mature them, extrude, calender, and dry them to obtain polytetrafluoroethylene tape, stretch them, and heat-set them to obtain polytetrafluoroethylene film; The polytetrafluoroethylene membrane comprises the following components, by weight: 110 parts of polytetrafluoroethylene resin, 32 parts of isomeric dodecane; Step 2: Preparation of amino polytetrafluoroethylene membrane: The polytetrafluoroethylene membrane was immersed in an ethanol-deionized water solution with a volume ratio of 1:1 for 20 minutes, and then washed with deionized water. Then, the treated polytetrafluoroethylene membrane was immersed in a 1,3-diaminopropane solution with a concentration of 1 mg / mL for 2 hours, and then washed with deionized water and dried to obtain an amino polytetrafluoroethylene membrane; Step 3: Preparation of amino hyaluronic acid: Take 1 g of hyaluronic acid and 100 mL of deionized water, stir evenly, add 1 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.2 g of N-hydroxysuccinimide, stir evenly, add 3 g of cystamine dihydrochloride, stir for 7 h, dialyze, and freeze-dry to obtain amino hyaluronic acid; Step 4: Preparation of modified hyaluronic acid: Take 0.1 g of folic acid and 100 mL of dimethyl sulfoxide, stir evenly, add 0.05 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.1 g of N-hydroxysuccinimide, stir for 70 min to obtain a mixed solution A; take 1 g of amino hyaluronic acid and 50 mL of phosphate buffer with a pH value of 7.4, stir evenly, add them dropwise to the mixed solution A, stir for 26 h, dialyze, and lyophilize to obtain a mixture A; Take 0.1 g of thioglycolic acid and 10 mL of phosphate buffer with a pH value of 7.4, stir evenly, add 0.4 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.25 g of N-hydroxysuccinimide, stir evenly, and obtain a mixed solution B; take 0.2 g of mixture A and 20 mL of phosphate buffer with a pH value of 7.4, stir evenly, add the mixed solution B dropwise, stir for 26 hours, dialyze, and freeze-dry to obtain modified hyaluronic acid; Step 5: Preparation of Dendrobium polysaccharide-hyaluronic acid mixed solution: Take 0.1g of dendrobium polysaccharide and 20mL of ethyl acetate, and disperse them by ultrasonication to obtain a dendrobium polysaccharide solution; take 1g of modified hyaluronic acid and 100mL of phosphate buffer with a pH value of 7.4, stir evenly, add the dendrobium polysaccharide solution, ultrasonicate for 30min, add 0.1g of copper chloride, and stir for 4h to obtain a dendrobium polysaccharide-hyaluronic acid mixed solution; Step 6: Preparation of polytetrafluoroethylene membrane for air filtration: The Dendrobium polysaccharide-hyaluronic acid mixed solution was coated on the surface of a 250µm thick amino polytetrafluoroethylene membrane with a coating thickness of 1µm, and then dried to obtain a polytetrafluoroethylene membrane for air filtration.

[0020] Comparative Example 1: The polytetrafluoroethylene membrane is not subjected to amination treatment, and the rest is the same as Example 1: Step 1: Preparation of polytetrafluoroethylene membrane: Take polytetrafluoroethylene resin and isododecane, mix them evenly, mature them, extrude, calender, and dry them to obtain polytetrafluoroethylene tape, stretch them, and heat-set them to obtain polytetrafluoroethylene film; The polytetrafluoroethylene membrane comprises the following components, by weight: 105 parts of polytetrafluoroethylene resin, 30 parts of isomeric dodecane; Step 2: Preparation of amino hyaluronic acid: Take 1 g of hyaluronic acid and 100 mL of deionized water, stir evenly, add 1 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.2 g of N-hydroxysuccinimide, stir evenly, add 3 g of cystamine dihydrochloride, stir for 6 h, dialyze, and freeze-dry to obtain amino hyaluronic acid; Step 3: Preparation of modified hyaluronic acid: Take 0.1 g of folic acid and 100 mL of dimethyl sulfoxide, stir evenly, add 0.05 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.1 g of N-hydroxysuccinimide, stir for 65 min to obtain a mixed solution A; take 1 g of amino hyaluronic acid and 50 mL of phosphate buffer with a pH value of 7.4, stir evenly, add them dropwise to the mixed solution A, stir for 24 h, dialyze, and lyophilize to obtain a mixture A; Take 0.1 g of thioglycolic acid and 10 mL of phosphate buffer with a pH value of 7.4, stir evenly, add 0.4 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.25 g of N-hydroxysuccinimide, stir evenly, and obtain a mixed solution B; take 0.2 g of mixture A and 20 mL of phosphate buffer with a pH value of 7.4, stir evenly, add the mixed solution B dropwise, stir for 24 hours, dialyze, and freeze-dry to obtain modified hyaluronic acid; Step 4: Preparation of Dendrobium polysaccharide-hyaluronic acid mixed solution: Take 0.1g of dendrobium polysaccharide and 20mL of ethyl acetate, and disperse them by ultrasonication to obtain a dendrobium polysaccharide solution; take 1g of modified hyaluronic acid and 100mL of phosphate buffer with a pH value of 7.4, stir evenly, add the dendrobium polysaccharide solution, ultrasonicate for 25min, add 0.1g of copper chloride, and stir for 3.5h to obtain a dendrobium polysaccharide-hyaluronic acid mixed solution; Step 5: Preparation of polytetrafluoroethylene membrane for air filtration: The Dendrobium polysaccharide-hyaluronic acid mixed solution was coated on the surface of a 250µm thick polytetrafluoroethylene membrane with a coating thickness of 1µm, and then dried to obtain a polytetrafluoroethylene membrane for air filtration.

[0021] Comparative Example 2: No dendrobium polysaccharide was added, and the rest was the same as Example 1: Step 1: Preparation of polytetrafluoroethylene membrane: Take polytetrafluoroethylene resin and isododecane, mix them evenly, mature them, extrude, calender, and dry them to obtain polytetrafluoroethylene tape, stretch them, and heat-set them to obtain polytetrafluoroethylene film; The polytetrafluoroethylene membrane comprises the following components, by weight: 105 parts of polytetrafluoroethylene resin, 30 parts of isomeric dodecane; Step 2: Preparation of amino polytetrafluoroethylene membrane: The polytetrafluoroethylene membrane was immersed in an ethanol-deionized water solution with a volume ratio of 1:1 for 18 minutes, and then washed with deionized water. Then, the treated polytetrafluoroethylene membrane was immersed in a 1,3-diaminopropane solution with a concentration of 1 mg / mL for 1.7 hours, and then washed with deionized water and dried to obtain an amino polytetrafluoroethylene membrane; Step 3: Preparation of amino hyaluronic acid: Take 1 g of hyaluronic acid and 100 mL of deionized water, stir evenly, add 1 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.2 g of N-hydroxysuccinimide, stir evenly, add 3 g of cystamine dihydrochloride, stir for 6 h, dialyze, and freeze-dry to obtain amino hyaluronic acid; Step 4: Preparation of modified hyaluronic acid: Take 0.1 g of folic acid and 100 mL of dimethyl sulfoxide, stir evenly, add 0.05 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.1 g of N-hydroxysuccinimide, stir for 65 min to obtain a mixed solution A; take 1 g of amino hyaluronic acid and 50 mL of phosphate buffer with a pH value of 7.4, stir evenly, add them dropwise to the mixed solution A, stir for 24 h, dialyze, and lyophilize to obtain a mixture A; Take 0.1 g of thioglycolic acid and 10 mL of phosphate buffer with a pH value of 7.4, stir evenly, add 0.4 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.25 g of N-hydroxysuccinimide, stir evenly, and obtain a mixed solution B; take 0.2 g of mixture A and 20 mL of phosphate buffer with a pH value of 7.4, stir evenly, add the mixed solution B dropwise, stir for 24 hours, dialyze, and freeze-dry to obtain modified hyaluronic acid; Step 5: Preparation of modified hyaluronic acid mixture: Take 1 g of modified hyaluronic acid and 100 mL of phosphate buffer with a pH value of 7.4, stir evenly, add 0.1 g of copper chloride, stir for 3.5 h, and obtain a modified hyaluronic acid mixed solution; Step 6: Preparation of polytetrafluoroethylene membrane for air filtration: The modified hyaluronic acid mixture was coated on the surface of a 250µm thick amino polytetrafluoroethylene membrane to a coating thickness of 1µm, and dried to obtain a polytetrafluoroethylene membrane for air filtration.

[0022] Comparative Example 3: No copper chloride is added, and the rest is the same as Example 1: Step 1: Preparation of polytetrafluoroethylene membrane: Take polytetrafluoroethylene resin and isododecane, mix them evenly, mature them, extrude, calender, and dry them to obtain polytetrafluoroethylene tape, stretch them, and heat-set them to obtain polytetrafluoroethylene film; The polytetrafluoroethylene membrane comprises the following components, by weight: 105 parts of polytetrafluoroethylene resin, 30 parts of isomeric dodecane; Step 2: Preparation of amino polytetrafluoroethylene membrane: The polytetrafluoroethylene membrane was immersed in an ethanol-deionized water solution with a volume ratio of 1:1 for 18 minutes, and then washed with deionized water. Then, the treated polytetrafluoroethylene membrane was immersed in a 1,3-diaminopropane solution with a concentration of 1 mg / mL for 1.7 hours, and then washed with deionized water and dried to obtain an amino polytetrafluoroethylene membrane; Step 3: Preparation of amino hyaluronic acid: Take 1 g of hyaluronic acid and 100 mL of deionized water, stir evenly, add 1 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.2 g of N-hydroxysuccinimide, stir evenly, add 3 g of cystamine dihydrochloride, stir for 6 h, dialyze, and freeze-dry to obtain amino hyaluronic acid; Step 4: Preparation of modified hyaluronic acid: Take 0.1 g of folic acid and 100 mL of dimethyl sulfoxide, stir evenly, add 0.05 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.1 g of N-hydroxysuccinimide, stir for 65 min to obtain a mixed solution A; take 1 g of amino hyaluronic acid and 50 mL of phosphate buffer with a pH value of 7.4, stir evenly, add them dropwise to the mixed solution A, stir for 24 h, dialyze, and lyophilize to obtain a mixture A; Take 0.1 g of thioglycolic acid and 10 mL of phosphate buffer with a pH value of 7.4, stir evenly, add 0.4 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.25 g of N-hydroxysuccinimide, stir evenly, and obtain a mixed solution B; take 0.2 g of mixture A and 20 mL of phosphate buffer with a pH value of 7.4, stir evenly, add the mixed solution B dropwise, stir for 24 hours, dialyze, and freeze-dry to obtain modified hyaluronic acid; Step 5: Preparation of Dendrobium polysaccharide-hyaluronic acid mixed solution: Take 0.1g of dendrobium polysaccharide and 20mL of ethyl acetate, and disperse them by ultrasonication to obtain a dendrobium polysaccharide solution; take 1g of modified hyaluronic acid and 100mL of phosphate buffer with a pH value of 7.4, stir evenly, add the dendrobium polysaccharide solution, and ultrasonicate for 25min to obtain a dendrobium polysaccharide-hyaluronic acid mixed solution; Step 6: Preparation of polytetrafluoroethylene membrane for air filtration: The Dendrobium polysaccharide-hyaluronic acid mixed solution was coated on the surface of a 250µm thick amino polytetrafluoroethylene membrane with a coating thickness of 1µm, and then dried to obtain a polytetrafluoroethylene membrane for air filtration.

[0023] experiment: The performance of the polytetrafluoroethylene membranes for air filtration prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested. The sterilized polytetrafluoroethylene membranes for air filtration were placed in a culture dish, and 200 μL of a 10% aqueous solution was added to the center of the polytetrafluoroethylene membranes. 6 The E. coli solution with a CFU / mL was placed in a 37℃ constant temperature incubator for 18 hours and then its antibacterial rate was tested. The filter was used to test the filtration efficiency of particles with a particle size of 0.1-0.2µm. The data obtained are shown in the following table:

[0024] Conclusion: From the comparison of the data in the table, it can be seen that in Comparative Example 1, the polytetrafluoroethylene membrane is not subjected to an amination treatment, the active sites on the surface of the polytetrafluoroethylene membrane are reduced, the amount of dendrobium polysaccharide-hyaluronic acid components that can be loaded is reduced, and the antibacterial properties of the polytetrafluoroethylene membrane are reduced. In Comparative Example 2, no dendrobium polysaccharide is added, and the antibacterial properties of the polytetrafluoroethylene membrane are reduced. In Comparative Example 3, copper chloride is not added, the antibacterial rate is reduced, and the antibacterial properties of the polytetrafluoroethylene membrane are reduced. Examples 1 to 3 of the present invention prepare a polytetrafluoroethylene membrane using polytetrafluoroethylene resin and isomeric dodecane. Then, the polytetrafluoroethylene membrane is subjected to an amination treatment, so that the active sites on the surface of the polytetrafluoroethylene membrane are increased, and more dendrobium polysaccharide-hyaluronic acid components can be loaded. In the present invention, a layer of dendrobium polysaccharide-hyaluronic acid mixed solution is coated on the surface of the amino polytetrafluoroethylene film in Examples 1 to 3. Dendrobium polysaccharide has a good antibacterial effect on Staphylococcus aureus and Escherichia coli, and can improve the antibacterial properties of the polytetrafluoroethylene film. Hyaluronic acid is modified and then dendrobium polysaccharide is compounded with it, which can achieve a good sustained release effect, enhance antibacterial properties, reduce the attachment and reproduction of microorganisms on the film surface, and further improve air quality. The present invention also adds copper chloride to the dendrobium polysaccharide-hyaluronic acid mixed solution, and copper chloride can destroy the microbial cell membrane, thereby achieving an antibacterial effect and improving the antibacterial properties of the polytetrafluoroethylene film.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a polytetrafluoroethylene membrane for air filtration, characterized in that: The following steps are involved: Step 1: Take polytetrafluoroethylene resin and isododecane, mix them evenly, mature them, extrude, calender, and dry them to obtain a polytetrafluoroethylene tape, stretch them, and heat-set them to obtain a polytetrafluoroethylene film; Step 2: Soak the polytetrafluoroethylene membrane in an ethanol and deionized water solution for 15-20 minutes, wash it with deionized water, and then soak the treated polytetrafluoroethylene membrane in a 1,3-diaminopropane solution for 1.5-2 hours, wash it with deionized water, and dry it to obtain an amino polytetrafluoroethylene membrane; Step 3: coating the mixed solution of dendrobium polysaccharide and hyaluronic acid on the surface of the amino polytetrafluoroethylene membrane and drying it to obtain the polytetrafluoroethylene membrane for air filtration.

2. The method for preparing a polytetrafluoroethylene membrane for air filtration according to claim 1, characterized in that: The preparation method of the dendrobium polysaccharide-hyaluronic acid mixed solution is as follows: taking dendrobium polysaccharide and ethyl acetate, ultrasonically dispersing to obtain a dendrobium polysaccharide solution; taking modified hyaluronic acid and phosphate buffer, stirring evenly, adding the dendrobium polysaccharide solution, ultrasonically treating for 20-30 minutes, adding copper chloride, stirring for 3-4 hours, and obtaining a dendrobium polysaccharide-hyaluronic acid mixed solution.

3. The method for preparing a polytetrafluoroethylene membrane for air filtration according to claim 2, characterized in that: The preparation method of the modified hyaluronic acid comprises the following steps: S1: Take folic acid and dimethyl sulfoxide, stir evenly, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, stir for 60-70 minutes to obtain a mixed solution A; take amino hyaluronic acid and phosphate buffer, stir evenly, add them dropwise to the mixed solution A, stir for 22-26 hours, dialyze, and freeze-dry to obtain a mixture A; S2: Take thioglycolic acid and phosphate buffer, stir evenly, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, stir evenly to obtain a mixed solution B; take mixture A and phosphate buffer, stir evenly, add mixed solution B dropwise, stir for 22-26 hours, dialyze, and lyophilize to obtain modified hyaluronic acid.

4. The method for preparing a polytetrafluoroethylene membrane for air filtration according to claim 3, characterized in that: In S1, the preparation method of amino hyaluronic acid is: take hyaluronic acid and deionized water, stir evenly, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, stir evenly, add cystamine dihydrochloride, stir for 5-7h, dialyze, and freeze-dry to obtain amino hyaluronic acid.

5. The method for preparing a polytetrafluoroethylene membrane for air filtration according to claim 1, characterized in that: The polytetrafluoroethylene film comprises the following components, by weight: 100-110 parts of polytetrafluoroethylene resin and 28-32 parts of isomeric dodecane.

6. The method for preparing a polytetrafluoroethylene membrane for air filtration according to claim 1, characterized in that: In step 3, the coating thickness of the Dendrobium polysaccharide-hyaluronic acid mixture is 1-1.5µm.

7. The method for preparing a polytetrafluoroethylene membrane for air filtration according to claim 2, characterized in that: The particle size of the dendrobium polysaccharide is 80 meshes to 120 meshes.

8. A polytetrafluoroethylene membrane for air filtration prepared according to the method for preparing a polytetrafluoroethylene membrane for air filtration according to any one of claims 1 to 7.

Images