阅读说明：本技术 一种可重复水洗的复合空气滤料及其制备方法 (Composite air filter material capable of being washed repeatedly and preparation method thereof ) 是由 李婷婷 岑喜喜 林佳弘 楼静文 张莹 于 2020-06-05 设计创作，主要内容包括：本发明公开了一种可重复水洗的复合空气滤料及其制备方法,属于产业用纺织品领域,具体方法是：步骤1、将聚丙烯和聚碳酸酯干燥混合后通过单螺杆造粒机制备出双组分聚丙烯/聚碳酸酯混合母粒；步骤2、将步骤1制得的母粒吹至成聚丙烯-聚碳酸酯熔喷滤料(PPC)；步骤3、六水合硝酸锌、2-甲基咪唑和无水甲醇通过原位生长法将沸石咪唑酯骨架生长于步骤2所制得的PPC上,制得聚丙烯-聚碳酸酯/沸石咪唑酯骨架熔喷滤料(PPC/ZIF-8)；步骤4、将六水合硝酸锌、2-甲基咪唑和无水甲醇以9.08∶72.35∶6292.13的摩尔比制备成沸石咪唑酯骨架(ZIF-8)纳米晶体；步骤5、将含ZIF-8纳米晶体的聚偏氟乙烯纺丝液与步骤3所制得的PPC/ZIF-8滤料复合,制成可重复水洗的复合滤料(PPC/PVDF/ZIF-8)。本发明所制备的PPC/PVDF/ZIF-8空气滤料能在高效低阻的前提下有效增强过滤效率,且遇水后的PM<Sub>2.5</Sub>过滤性能稳定。(The invention discloses a composite air filter material capable of being repeatedly washed by water and a preparation method thereof, belonging to the field of industrial textiles and comprising the following specific steps: step 1, drying and mixing polypropylene and polycarbonate, and preparing a bi-component polypropylene/polycarbonate mixed master batch by a single-screw granulator; step 2, blowing the master batch prepared in the step 1 into polypropylene-polycarbonateMelt blown filter material (PPC); step 3, growing a zeolite imidazole ester framework on the PPC prepared in the step 2 by using zinc nitrate hexahydrate, 2-methylimidazole and anhydrous methanol through an in-situ growth method to prepare a polypropylene-polycarbonate/zeolite imidazole ester framework melt-blown filter material (PPC/ZIF-8); step 4, preparing zinc nitrate hexahydrate, 2-methylimidazole and anhydrous methanol into zeolite imidazolate framework (ZIF-8) nanocrystals according to a molar ratio of 9.08: 72.35: 6292.13; and 5, compounding the polyvinylidene fluoride spinning solution containing the ZIF-8 nanocrystals with the PPC/ZIF-8 filter material prepared in the step 3 to prepare the composite filter material (PPC/PVDF/ZIF-8) capable of being repeatedly washed by water. The PPC/PVDF/ZIF-8 air filter material prepared by the invention can effectively enhance the filtering efficiency on the premise of high efficiency and low resistance, and PM after meeting water 2.5 The filtering performance is stable.)

1. A composite air filter material capable of being washed repeatedly and a preparation method thereof are characterized by comprising the following steps:

step 1, mixing polypropylene and polycarbonate polymer in a ratio of 99 percent to 1-93 percent to 7 percent to prepare bi-component polypropylene/polycarbonate master batch;

step 2, drying the polypropylene/polycarbonate master batch obtained in the step 1 by using an air-blast drying oven at the drying temperature of 50-80 ℃ for 3-6 h; adopting a single-screw extruder, fully melting the master batch obtained in the step (1) under the action of high temperature and shearing force of a screw, sequentially passing through a pipeline, a metering pump and a die head, and then blowing the polymer from the die head to a collecting net curtain with an air suction device under the action of high-speed hot air in a hot air pipe; finally, winding the filter material on a cloth roller to prepare a polypropylene-polycarbonate melt-blown filter material (PPC); wherein the hot air temperature is 200-;

step 3, dissolving zinc nitrate hexahydrate in anhydrous methanol, and then soaking the PPC filter material prepared in the step 2 in a zinc nitrate hexahydrate-methanol mixed solution to ensure that the filter material is completely contacted with the solution; dissolving 2-methylimidazole in anhydrous methanol, and pouring into a zinc nitrate hexahydrate methanol solution soaked with a PPC filter material; after full reaction, taking out the PPC filter material, washing with fresh anhydrous methanol, and drying to obtain a polypropylene-polycarbonate/zeolite imidazole ester framework melt-blown filter material (PPC/ZIF-8); wherein, zinc nitrate hexahydrate, 2-methylimidazole and anhydrous methanol are prepared into a ZIF-8 precursor solution according to the molar ratio of 1: 50-105: 700-9100-; drying at 50-80 deg.C for 3-6 h;

step 4, respectively dissolving zinc nitrate hexahydrate and 2-methylimidazole in anhydrous methanol at the temperature of 20-25 ℃; slowly pouring the mixed solution containing 2-methylimidazole/anhydrous methanol into a methanol solution containing zinc nitrate hexahydrate; after standing, centrifuging the product, washing with fresh methanol, and drying to obtain zeolite imidazole ester framework (ZIF-8) nanocrystal; wherein, the standing time is 12-24 h; the centrifugal speed is 3500-8000 rpm;

step 5, ultrasonically dispersing the ZIF-8 nanocrystal prepared in the step 4 and an N, N-dimethylformamide solvent, adding polyvinylidene fluoride, heating and stirring in a water bath to prepare an electrostatic spinning solution; fixing the PPC/ZIF-8 melt-blown filter material prepared in the step 3 on a winding roller of electrostatic spinning equipment; injecting the electrostatic spinning solution into a double-injector, and spinning the spinning solution on the surface of the filter material under the action of a positive high-voltage power supply to prepare the polypropylene-polycarbonate/polyvinylidene fluoride/zeolite imidazole ester framework melt-blown electrostatic spinning composite filter material (PPC/PVDF/ZIF-8).

2. The preparation method of the repeatedly washable composite air filter material as claimed in claim 1, wherein in step 3, the materials of the ZIF-8 in-situ growth precursor solution are respectively zinc nitrate hexahydrate, 2-methylimidazole and anhydrous methanol, and the reaction is carried out at normal temperature. The stirring speed and the stirring time of the zinc nitrate hexahydrate or the 2-methylimidazole and the anhydrous methanol are respectively 400-600r/min and 30-60 min.

3. The method for preparing the repeatedly washable composite air filter material as claimed in claim 1, wherein in the step 3, the time for completely soaking the melt-blown filter material in the zinc nitrate hexahydrate/anhydrous methanol mixed solution is 12-24 hours; slowly pouring the 2-methylimidazole/anhydrous methanol mixed solution into a culture dish containing the PPC melt-blown filter material, and reacting with a methanol solution containing zinc nitrate hexahydrate for 1-2 hours; washing the PPC melt-blown filter material after reaction with fresh anhydrous methanol for 8-10 times, and then drying at room temperature; wherein, zinc nitrate hexahydrate, 2-methylimidazole and anhydrous methanol are prepared into ZIF-8 precursor solution according to the molar ratio of 1: 50-105: 800-9100.

4. The method for preparing the repeatedly washable composite air filter material as claimed in claim 1, wherein in step 4, the stirring speed and the stirring time of zinc nitrate hexahydrate or 2-methylimidazole and anhydrous methanol are respectively 400-600r/min and 30-60 min; stirring the mixed solution of 2-methylimidazole/anhydrous methanol and zinc nitrate hexahydrate/anhydrous methanol at the stirring speed of 400-600r/min for 3-4h, and standing for 12-24 h; centrifuging the product and washing with fresh methanol for 3-5 times; wherein the molar ratio of the zinc nitrate hexahydrate, the 2-methylimidazole and the anhydrous methanol is 1: 8: 690.

5. The preparation method of the repeatedly washable composite air filter material as recited in claim 1, wherein in step 5, the zeolite imidazole ester framework and the N, N-dimethylformamide solvent are ultrasonically dispersed for 2-3 hours, and heated and stirred in a water bath for 6-8 hours after polyvinylidene fluoride is added to prepare an electrostatic spinning solution; the spinning solution amount in the double injector is 3ml, the high-voltage power supply voltage, the moving distance and the injection pump speed are 23-25kV, 155-160cm and 0.8-0.9mm/l respectively; wherein the zeolite imidazole ester framework, the polyvinylidene fluoride and the N, N-dimethylformamide are prepared into the electrostatic spinning solution according to the mass ratio of 0-0.8: 0-7.2: 0-92.

6. A composite air filter material capable of being repeatedly washed by water, which is obtained according to any one of claims 1 to 5, is characterized in that the material can effectively enhance the filtering efficiency on the premise of high efficiency and low resistance, and PM after meeting water_2.5The filtering performance is stable, and the filtering performance is still in a higher level even after 5 times of filtering, washing and drying.

The technical field is as follows:

the invention relates to the field of industrial textiles, in particular to a polypropylene-polycarbonate/polyvinylidene fluoride/zeolite imidazolate framework melt-blown electrostatic spinning composite air filter material and a preparation method thereof, which are suitable for the air filtration industry.

Background art:

in recent years, serious air pollution problems have seriously threatened human health, especially in the air, fine Particulate Matter (PM) having an aerodynamic diameter of 2.5 μm or less_2.5). At present, PM is removed efficiently_2.5The air fiber filter material mainly comprises a common non-woven fiber filter material, an ultrafine glass fiber filter material, an electrostatic spinning fiber filter material and an electret fiber filter material. The electret fiber filter material is widely researched and applied by people because the electret fiber filter material can effectively improve the filtering efficiency and does not influence the pressure drop value. However, although the filtering performance of the electret fiber filtering material is obviously improved compared with the traditional filtering material, the depth of the charge injection trap has certain limitation, so that the charges residing on the filtering material can be rapidly dissipated after being wetted. Thus, preparation of post-water PM_2.5The high-efficiency low-resistance air filter material with stable filtering performance becomes an important breakthrough.

The diameter of the fiber of the filter material prepared by the electrostatic spinning process is generally between 100 and 500nm, and the fiber has larger specific surface area, surface energy and smaller pore diameter, but the compact fiber net structure can increase the filter pressure drop value and is not favorable for the comfort of the filter material when being worn. The fiber filter material prepared by adopting the melt-blown process has the advantages of high porosity, long filtering channel, low pressure drop, high yield, high strength and the like, but the fiber diameter is mostly in micron-scale, the pore diameter among the fibers is larger, and the PM is difficult to realize_2.5The high-efficiency filtration is realized. Therefore, the performance advantages of the melt-blowing process and the electrostatic spinning process can be effectively exerted by combining the melt-blowing process and the electrostatic spinning process.

The zeolite imidazolate framework (ZIF-8) is a novel porous hybrid material, has the characteristics of high porosity, high hydrothermal resistance, high specific surface area, highly adjustable pore diameter and the like, and has great application potential in the fields of gas storage and separation, catalysis, electronics, sensors and medicines. At present, four methods are mainly used for effectively loading ZIF-8 on a supporting material, namely a mechanical method, an adhesive method, an electrostatic spinning method and an in-situ growth method. The in-situ growth method can effectively maintain the original structure and activity of the ZIF-8 and has advantages in exerting the performance of the ZIF-8. However, according to the existing research, the air filter material prepared by the conventional in-situ growth method can effectively improve the filtering efficiency but greatly increase the pressure drop value, and the reactions are finished in an autoclave and are not suitable for mass production.

In order to overcome the defects of the conventional air filter material and the conventional ZIF-8 in-situ growth method, the invention adopts a melt-blown electrospinning composite process and a ZIF-8 in-situ growth method which has mild preparation conditions and is suitable for mass production, so that the prepared PM has good stability and long service life_2.5The air filter material has the advantages of high efficiency, low resistance and stable filtering performance after meeting water.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to solve the technical problem of providing a polypropylene-polycarbonate/polyvinylidene fluoride/zeolite imidazolate framework melt-blown electrostatic spinning composite air filter material and a preparation method thereof.

The technical scheme for solving the technical problems of the method is to provide a preparation method of a polypropylene-polycarbonate/polyvinylidene fluoride/zeolite imidazolate framework melt-blown electrospun composite air filter material, which is characterized by comprising the following steps:

step 1, mixing polypropylene and polycarbonate polymer in a ratio of 99 percent to 1-93 percent to 7 percent to prepare bi-component polypropylene/polycarbonate master batch;

step 2, drying the polypropylene/polycarbonate master batch obtained in the step 1 by using an air-blast drying oven at the drying temperature of 50-80 ℃ for 3-6 h; adopting a single-screw extruder, fully melting the master batch obtained in the step (1) under the action of high temperature and shearing force of a screw, sequentially passing through a pipeline, a metering pump and a die head, and then blowing the polymer from the die head to a collecting net curtain with an air suction device under the action of high-speed hot air in a hot air pipe; finally, winding the filter material on a cloth roller to prepare a polypropylene-polycarbonate melt-blown filter material (PPC); wherein the hot air temperature is 200-.

Step 3, dissolving zinc nitrate hexahydrate in anhydrous methanol, and then soaking the PPC filter material prepared in the step 2 in a zinc nitrate hexahydrate-methanol mixed solution to ensure that the filter material is completely contacted with the solution; dissolving 2-methylimidazole in anhydrous methanol, and pouring into a zinc nitrate hexahydrate methanol solution soaked with a PPC filter material; after full reaction, taking out the PPC filter material, washing with fresh anhydrous methanol, and drying to obtain a polypropylene-polycarbonate/zeolite imidazole ester framework melt-blown filter material (PPC/ZIF-8); wherein zinc nitrate hexahydrate, 2-methylimidazole and anhydrous methanol are prepared into a ZIF-8 precursor solution in a molar ratio of 1: 50-105: 800-9100; the drying temperature is 50-80 ℃, and the drying time is 3-6 h.

Step 4, respectively dissolving zinc nitrate hexahydrate and 2-methylimidazole in anhydrous methanol at the temperature of 20-25 ℃; slowly pouring the mixed solution containing 2-methylimidazole/anhydrous methanol into a methanol solution containing zinc nitrate hexahydrate; after standing, centrifuging the product, washing with fresh methanol, and drying to obtain zeolite imidazole ester framework (ZIF-8) nanocrystal; wherein, the standing time is 12-24 h; the centrifugal speed is 3500-8000 rpm;

step 5, carrying out ultrasonic dispersion on the ZIF-8 nanocrystal prepared in the step 4 and an N, N-dimethylformamide solvent, adding polyvinylidene fluoride, heating and stirring in a water bath to prepare an electrostatic spinning solution; fixing the PPC/ZIF-8 melt-blown filter material prepared in the step 3 on a winding roller of electrostatic spinning equipment; injecting the electrostatic spinning solution into a double-injector, and spinning the spinning solution on the surface of the filter material under the action of a positive high-voltage power supply to prepare the polypropylene-polycarbonate/polyvinylidene fluoride/zeolite imidazole ester framework melt-blown electrostatic spinning composite filter material (PPC/PVDF/ZIF-8). Preparing the zeolite imidazole ester framework, polyvinylidene fluoride and N, N-dimethylformamide into electrostatic spinning solution according to the mass ratio of 0-0.8: 0-7.2: 0-92.

The invention isThe technical scheme for solving the technical problem of the material is to provide the composite air filter material which can be repeatedly washed by water according to the method. It is characterized in that the filter material can filter PM in air with high efficiency and low resistance_2.5And PM after meeting water_2.5The filtering performance is stable.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention combines melt-blown technology and electrostatic spinning technology, and the prepared PPC melt-blown filter material effectively exerts the performance advantages of the melt-blown filter material and the electrostatic spinning technology, and achieves the primary aim of high efficiency and low resistance.

(2) The invention adopts polypropylene-polycarbonate/polyvinylidene fluoride/zeolite imidazole ester as a framework structure to prepare the composite filter material, thereby obviously improving PM after meeting water_2.5And (4) filtering and stabilizing performance.

(3) The method adopted by the invention has the advantages of simple process and mild preparation conditions, and is suitable for batch production.

Drawings

FIG. 1 is a schematic illustration of the preparation of a re-washable composite air filter material (PPC/ZIF-8) according to one embodiment of the present invention;

FIG. 2 is a schematic of the preparation of a zeolitic imidazolate framework (ZIF-8) nanocrystal of one embodiment of the present invention;

FIG. 3 is a graph of the fiber surface topography of (a) a polypropylene-polycarbonate melt blown filter material and (b) a polypropylene-polycarbonate/zeolitic imidazolate framework melt blown filter material in accordance with one embodiment of the present invention;

FIG. 4 shows the polypropylene-polycarbonate/zeolitic imidazolate framework meltblown filter media at different zeolitic imidazolate framework precursor concentrations of an embodiment of the present invention (a) filtration efficiency at different PM particle sizes, (b) PM_2.5And PM₅Filtration efficiency, (c) pressure drop and (d) PM_2.5Filtering the quality factor graph;

FIG. 5 is a graph of (a) filtration efficiency, pressure drop, and (d) quality factor for a PPC/ZIF8-9 meltblown filter of one embodiment of the present invention after a filter-wash-dry cycle;

FIG. 6 is a graph of (a) fiber surface topography, (b) average fiber diameter, and (c) fiber distribution of a re-washable composite filter of an embodiment of the present invention;

FIG. 7 shows an embodiment of the invention of (a) PM of a polypropylene-polycarbonate/polyvinylidene fluoride/zeolitic imidazolate framework meltblown electrospun composite filter_2.5Filtration efficiency, (b) pressure drop, and (c) quality factor graph;

fig. 8 is (a) a graph of filtration efficiency, pressure drop, and (b) a graph of quality factor for a PPC/PVDF/ZIF8-3 meltblown electrospun composite filter after a filtration-washing-drying cycle in accordance with an embodiment of the present invention.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.