CN104289042B - A kind of electrostatic spinning nano fiber electret filtering material and preparation method thereof - Google Patents

Abstract

The invention relates to an electrospinning nanofiber electret filter material and a preparation method thereof. During the electrospinning process, the components and temperature of the polymer solution are controlled, and the nanofiber forming "rapid cooling" process is used to form and prepare fibers without adhesion in one step. High-efficiency, low-resistance nanofiber electret filter material with a fluffy three-dimensional network structure, in which the nanofiber layer has a grammage of 0.01-70g/m ² and a porosity of ≥80%. The surface of the nanofiber electret composite filter material The electrostatic potential is 800-6000V, and the surface charge has long-term storage stability, the hydrophobic angle is greater than 150°, the filtration efficiency of particles 0.006-1μm can reach more than 99.999%, the piezoresistance is less than 20Pa, and the dust holding capacity is 300-3600g/ m ² , the preparation process of the present invention is simple, and the filter material has broad application prospects in the fields of personal protective mask filtration, indoor air purification filtration, high-efficiency/ultra-high-efficiency air filtration, and the like.

Description

A kind of electrostatic spinning nanofiber electret filter material and preparation method thereof

technical field

The invention relates to an electrospun nanofiber electret filter material and a preparation method thereof, in particular to provide an electrospun nanofiber electret filter material that instantly cools down after the nanofibers are formed and "freezes" polarized charges and space charges and its preparation method.

Background technique

High-performance electrospun nanofiber filter materials need to have the characteristics of high efficiency and low resistance, but conventional filter materials rely on the structural characteristics of the material itself (pore size, packing density, etc.) to achieve effective filtration of particles, usually in high-efficiency At the same time, it also has a high pressure resistance, resulting in poor filtration performance, so it is difficult to achieve an effective balance between filtration efficiency and pressure resistance, high efficiency and low resistance only by the structural characteristics of the fiber itself. The introduction of electrostatic adsorption (electret material) can greatly improve the interception of particles by electrostatic adsorption on the basis of the structural efficiency of the original filter material, thereby improving the filtration efficiency, while ensuring the characteristics of low pressure resistance.

At present, the research, development and production of fiber electret materials mainly adopt high-voltage corona discharge and thermal polarization. Although it can better electret fiber filter material, it also has many shortcomings, such as: electret performance Unstable, the generated charge is mainly the space charge on the surface of the fiber and is prone to failure, the equipment is complicated, and the cost is high. The published patents for preparing electret fiber filter materials by using corona discharge and thermal polarization include: patent CN1427430A discloses a "multi-layer electret with ultra-high charging stability and its manufacturing method", which uses high-temperature heating of metal FEP film on the sheet and apply high voltage on it to make it melt and bond, then cool to complete the electret, and finally charge the cooled electret with electric charge; patent CN101071683A discloses "a polarization method of electret ", which melts the polymer film by heating up, and applies an external electric field to electret, and finally cools down to complete the electret process; patent CN101905101A discloses "a method for preparing a melt-blown polypropylene electret filter material", which passes high-speed Hot air blows the melt extruded from the spinneret hole into ultra-fine fibers, and at the same time makes the fibers pass through the electrodes of the corona discharge device to complete the electret; patent CN103240945A discloses "a method for preparing a composite polymer electret" The composite film is electretized by corona polarization or thermal polarization. These patented technologies all adopt electret polymer materials under high voltage after heating or high temperature treatment. It only drops to room temperature, resulting in the phenomenon of "depolarization" of polarized charges and the dissipation of space charges during the cooling process, and in the process of use, it is easily affected by environmental conditions and causes the charge performance to decay, resulting in the unsatisfactory electret performance. actual use requirements.

Contents of the invention

The purpose of the present invention is to provide a kind of electrostatic spinning nanofiber electret filter material and its preparation method, especially provide a kind of thermopolarized electrostatic spinning nanofiber electret filter material and its preparation method. The nanofiber preparation technology of piezoelectric spinning is also a nanofiber electret technology. Compared with corona discharge and thermal polarization electret technology, its advantage is that a large amount of space charge can be injected into the fiber during spinning. Among them, the space charge is easily captured by the deep trap inside the fiber, and at the same time it can induce dipole polarization to generate polarized charges. It produces a certain "thermal polarization effect", and after the nanofiber is formed, it instantly cools down to below 0° to freeze the polarized charge and space charge, preventing the "depolarization" phenomenon and the dissipation of space charge, thus The electrospinning method can be used to prepare nanofiber electret filter materials in one step, and has excellent electret effect.

Concrete implementation steps of the present invention are:

1) Prepare a polymer solution with a certain concentration (3-40%) or a mixture solution of two or three polymers or a polymer solution containing at least one inorganic nanoparticle, or a mixture solution of two or three polymers. The preparation process of different polymer solutions: ① The preparation process of the polymer solution without inorganic nanoparticles is: directly add a certain amount of one, two or three polymers to the corresponding solvent, and use a magnetic stirring device to continuously Stir for 3-20 hours to prepare a uniform and stable solution; ② The preparation process of the polymer containing inorganic nanoparticles is as follows: first add the inorganic nanoparticles to the solvent, and ultrasonically for 0.5-15 hours, and then a certain amount of a , Two or three kinds of polymers are added therein, and continuously stirred with a magnetic stirring device for 3-20 hours to prepare a uniform and stable solution.

2) Inhale a certain concentration (3-40%) of a polymer solution or a polymer solution containing inorganic nanoparticles into the spinneret module, where the spinneret module is connected to a temperature control device (temperature range: 30-120°C), which can make The solution in the spinneret module is kept at a certain temperature. At the same time, the spinneret module contains an online stirring device to make the inorganic nanoparticles evenly dispersed in the polymer and prevent agglomeration.

3) Spinning is carried out in the electrospinning unit. The needle at the front end of the spinning module is connected to a high-voltage power supply. The spun nanofibers are received by the substrate. ~100L/min) release device, which can instantly reduce the electrospun fiber material to a low temperature (less than 0°C), because the polymer solution will generate a large amount of polarized charges under the action of an electrostatic field, and the polarized charges at this time are easy Due to the influence of molecular chain movement and ambient temperature and humidity, the polarized molecules will depolarize, resulting in poor electret effect, and instant cooling can reduce the temperature of the polymer to a low temperature in a very short time. Below zero temperature, to quickly "freeze" the molecular chain to prevent the occurrence of depolarization, and at the same time cool the polymer instantly to reduce the kinetic energy of the space charge that the polymer has captured, reduce the ability of electrons to escape, and instantly strengthen the space charge. Storage, strengthen the electret effect. In addition, when nitrogen passes through the substrate at a certain speed, it will generate a reaction force for the flying nanofibers, hinder the tight arrangement between fibers, and help the formed nanofibers to form a fluffy structure, so as to form a fluffy and non-adhesive fiber structure. The high-efficiency and low-resistance electret filter material with a three-dimensional network interconnected structure, the formed hydrophobic (hydrophobic angle > 150°) nanofiber electret filter material can filter 0.02-6μm particles with a filtration efficiency of more than 99.999%. The resistance is less than 20Pa.

The process conditions of electrospinning are: voltage 5-70KV, receiving distance 3-40cm, perfusion speed 0.1-10mL/h, temperature 0-35°C, relative humidity 0-90%.

Among them, the positive effects produced by the "instantaneous cooling" treatment are: ① The electrostatic potential on the surface of the electret material is enhanced. The electrostatic potential on the surface of the electrode material is 800-6000V; ②The life of the electret is greatly enhanced: the charge of the ordinary electrospun electret material decays by 50% in half a year, and the electrospun electret material treated with "instantaneous cooling" saves the charge for half a year without decay.

As a preferred technical solution:

A preparation method of electrospun nanofiber electret filter material, comprising:

1) Electrospinning is performed after heating the polymer solution to 30-120°C;

2) The fiber obtained by electrospinning is quickly cooled to below 0° C. after being received by the receiving substrate, and the electrospun nanofiber electret filter material is obtained; the rapid cooling means that the distance between the spun nanofiber and the receiving substrate is less than When the thickness is 1mm, the nanofibers drop below 0°C within less than 5s after contacting with liquid nitrogen.

According to the above-mentioned preparation method of electrospun nanofiber electret filter material, the mass concentration of the polymer solution is 3-40%.

A kind of preparation method of electrospinning nanofiber electret filter material as above, the polymer that its spinning adopts is polyvinylidene fluoride, polypropylene, polybutylene terephthalate, polyethylene terephthalate Esters, polyarylates, polyvinyl acetate, nylon 6, polyvinyl alcohol, polymethylmethacrylate, polyaniline, polyethylene oxide, polyvinylpyrrolidone, polyacrylonitrile, polycaprolactone, polyethylene glycol, polyurethane , fluorinated polyurethane, polysulfone, polyethersulfone, polyvinylidene fluoride ~ hexafluoropropylene, polyvinylidene fluoride ~ tetrafluoroethylene ~ perfluoromethyl vinyl ether, polyvinylidene fluoride ~ trifluorochloroethylene species, or a mixture of any two or three polymers.

Said polymers include homopolymers, block copolymers, random copolymers, mixtures of two different homopolymers, mixtures of homopolymers and block copolymers, and mixtures of homopolymers and random copolymers;

The effect of the block copolymer and the random copolymer is: because different molecular chain parts of the block copolymer will form different crystalline regions and amorphous regions during the electrospinning process, electrons or ions will be in the The aggregation at the interface forms the polarization of the interface, resulting in polarized charges, and the nanofibers prepared by electrospinning a mixture of two or more polymers will consist of a variety of polymer components, and there will be interactions between different polymer components. The interface is formed, and the interface polarization will also be formed under the action of the external point formation, resulting in polarized charges.

A method for preparing an electrospun nanofiber electret filter material as described above, the solvent in the polymer solution corresponds to:

Polyvinylidene fluoride: N,N~dimethylformamide (DMF), N~methylpyrrolidone (NMP), dimethylacetamide (DMAc), triethyl phosphate and dimethyl sulfoxide (DMSO);

Polypropylene: n-heptane, tetrahydronaphthalene, xylene, etc.;

Polybutylene terephthalate: dichloromethane, tetrahydrofuran (THF), chloroform, acetone, etc.;

Polyethylene terephthalate: dichloromethane, tetrahydrofuran, chloroform, acetone, etc.;

Polyarylate: dichloromethane, tetrahydrofuran, chloroform, acetone, etc.;

Polyvinyl acetate: toluene, acetone, ethanol, acetic acid, ethyl acetate, chloroform, etc.;

The solvent of nylon 6 is formic acid;

Polyvinyl alcohol: water, ethanol, N,N-dimethylformamide, tetrahydrofuran;

Polymethyl methacrylate: chloroform, acetic acid, ethyl acetate, acetone, toluene, etc.;

Polyaniline: N,N~dimethylformamide, N~methylpyrrolidone, etc.;

Polyethylene oxide: N,N-dimethylformamide, ethanol, water, chloroform;

Polyvinylpyrrolidone: water, ethanol, N,N~dimethylacetamide, N,N~dimethylformamide, etc.;

Polyacrylonitrile: N,N～dimethylformamide, dimethyl sulfoxide, etc.;

Polycaprolactone: N,N～dimethylformamide, acetone, etc.;

Polyethylene glycol: water, ethanol, N,N-dimethylformamide, etc.;

Polyurethane: N,N~dimethylformamide, acetone, N~methylpyrrolidone, etc.;

Fluorinated polyurethane: N,N~dimethylformamide, acetone, N~methylpyrrolidone, etc.;

Polysulfone and polyethersulfone: N,N~dimethylformamide, acetone, N~methylpyrrolidone, dimethylacetamide, tetrahydrofuran, etc.;

Polyvinylidene fluoride-hexafluoropropylene: N,N~dimethylformamide, N~methylpyrrolidone, dimethylacetamide, triethyl phosphate and dimethyl sulfoxide, etc.;

Polyvinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether: N,N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, triethyl phosphate and dimethyl sulfoxide, etc. ;

Polyvinylidene fluoride-chlorotrifluoroethylene: N,N~dimethylformamide, N~methylpyrrolidone, dimethylacetamide, triethyl phosphate and dimethyl sulfoxide, etc.;

The solvent used for the mixture of any two or three polymers mentioned above is a mixture of solvents that can respectively dissolve a single polymer or a single solvent that can dissolve two or three polymers simultaneously.

A kind of electrospun nanofiber electret filter material as above, also contains at least one kind of inorganic nanoparticles in the polymer solution, the inorganic nanoparticles: silicon dioxide, aluminum oxide, zinc oxide, oxide Barium, titanium dioxide, tantalum pentoxide, barium titanate, lead zirconate titanate, silicon nitride, tourmaline, boehmite or silsesquioxane nanoparticles, etc.;

The added amount of the inorganic nanoparticles is: 0.1-10wt% of the total amount of the polymer and the inorganic nanoparticles;

The preparation process of the polymer solution containing inorganic nanoparticles is as follows: firstly add the inorganic nanoparticles into the solvent, and ultrasonicate for 0.5-15 hours, then add the polymer solution therein, and continuously stir for 3-20 hours with a magnetic stirring device, Formulated into a homogeneous and stable solution;

The mechanism of action of the inorganic nanoparticles is as follows: the inorganic nanoparticles will inject space charges and generate polarized charges under the condition of the presence of an external electric field, which greatly enhances the electret effect, and the inorganic electret and The interface generated by the mixing of organic polymers will produce interface polarization in the presence of an external electric field, resulting in polarized charges, which also enhances the electret effect. The nanofibrous membrane produces superhydrophobic properties.

A method for preparing an electrospun nanofiber electret filter material as described above, the spinneret module is connected to a temperature control device, and its purpose is to "thaw" the frozen polymer molecular chains in the solution by heating, which has Under the action of the subsequent external electric field, the dipole molecules are better polarized and more polarized charges are generated;

The heating means that the polymer is heated in the spinning module of electrospinning, that is, the spinning module is connected with a temperature control device; the spinning module also contains an online stirring device.

A method for preparing an electrospinning nanofiber electret filter material as described above, the process conditions of the electrospinning are: voltage 5-70KV, receiving distance 3-40cm, perfusion speed 0.1-10mL/h, temperature 0- 35°C, relative humidity 0-90%.

According to the above-mentioned nanofiber electret air filter material, the receiving method of the nanofibers is: flat plate receiving or hollow flat plate receiving, and the receiving method is up and down receiving or left and right receiving.

A method for preparing an electrospun nanofiber electret filter material as described above, the material of the substrate is: wood pulp cellulose substrate, fiber substrate or mixed fiber substrate;

The wood pulp cellulose substrate is a wood pulp cellulose filter paper or a wood pulp cellulose nonwoven fabric with a stiffness of 0.5 to 5 mN·m and a grammage of 8 to 400 g/m ² , and the wood pulp cellulose filter paper is a corrugated filter paper, wherein The corrugation distance of cellulose corrugated filter paper is 0-3mm;

The fiber substrate is filter paper or non-woven fabric containing cellulose fiber, polyester fiber, polyolefin fiber, its stiffness is 0.5-5mN·m, and its grammage is 6-350g/ ^m2 ; the fiber filter paper includes corrugated filter paper , wherein the corrugated distance of cellulose corrugated filter paper is 0-3mm;

The mixed fiber base material is a filter paper or a non-woven fabric containing mixed fibers composed of two or more of cellulose cellulose, polyester fibers, and polyolefin fibers, and its stiffness is 0.5 to 5 mN·m, and its grammage is 6-350g/m ² , the mixed fiber filter paper is corrugated filter paper, wherein the corrugated distance of the cellulose corrugated filter paper is 0mm-3mm.

A method for preparing an electrospun nanofiber electret filter material as described above, the cooling method is to install a liquid nitrogen constant-velocity release device at a distance of 1 to 100 mm from the back of the receiving substrate to release The speed is 1-100L/min.

An electrospun nanofiber electret filter material as described above, the electrospun nanofiber electret filter material is a two-layer composite structure of a substrate layer and a nanofiber layer;

The material of the substrate layer is porous wood pulp cellulose substrate, fiber substrate or mixed fiber substrate, the fiber diameter is 10-50 μm, and the pore size is 3-120 μm;

The nanofiber diameter of the nanofiber layer: 0.008-1 μm, the grammage of the nanofiber layer: 0.01-70 g/m ² , the porosity of the nanofiber layer ≥ 80%; the surface of the electrospun nanofiber electret filter material The electrostatic potential is 1700-2300V, the hydrophobic angle is more than 150°, the filtration efficiency of 0.006-1μm particles can reach more than 99.999%, the pressure resistance is less than 20Pa, and the dust holding capacity is 300-3600g/m ² .

Beneficial effect:

1. For the first time, the present invention controls the composition and temperature of the polymer solution, the content of inorganic nanoparticles, and the "instantaneous cooling" of nanofiber forming, so as to prepare a three-dimensional network-like interconnected structure nanofiber electret filter with no adhesion between fibers and a fluffy structure in one step. Materials, composite nanofiber electret materials have high surface electrostatic potential and super electrostatic adsorption performance.

2. The preparation method provided by the present invention has a simple process and is applicable to the preparation of a wide range of polymer-based nanofiber electret composite filter materials. In addition, the preparation method has good controllability of the fiber structure, and can precisely control the bulk density and wettability of the fiber membrane by controlling the release rate of liquid nitrogen and the content of inorganic nanoparticles.

3. The nanofiber filter material prepared by this patent has high surface electrostatic potential and excellent charge storage stability, so it has high electrostatic adsorption filtration performance, which is better than the existing fiber electret composite filter material.

4. The nanofiber electret composite filter material prepared by the present invention has a small pore size, high porosity, and a fluffy three-dimensional network structure. These characteristics of the material make it possible to ensure high filtration efficiency during actual use. It has extremely high air permeability, which will greatly reduce the actual energy consumption, and has a wide range of practical application prospects.

Description of drawings

Fig. 1 is a schematic diagram of the structure of spinning equipment, in which 1 is a spinning module, 2 is a temperature control device, 3 is a receiving substrate, 4 is a receiving and transporting device, and 5 is a liquid nitrogen constant release device.

Figure 2 is a graph showing the relationship between electrostatic adsorption filtration performance and temperature of electrospun nanofiber electret materials and commercial melt-blown PP non-woven fabrics. This figure shows that the electret filter material prepared by this patent has excellent electrostatic adsorption filtration performance and charge storage stability. .

detailed description

The present invention will be further described below in combination with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Example 1

An electrospun nanofiber electret filter material and a preparation method thereof, the specific steps are:

Step 1: Place the polyvinylidene fluoride powder in a vacuum oven at 80° C. for 3 hours to vacuum dry.

Step 2: Dissolve the dried polyvinylidene fluoride powder in N,N-dimethylformamide, place the solution on a magnetic stirrer and stir for 10 hours to form a homogeneous solution; the homogeneous In the solution, the mass fraction of polyvinylidene fluoride is 40%.

The third step: use the electrospinning equipment shown in Figure 1 to spin, first pump a certain amount of the above-mentioned polyvinylidene fluoride polymer solution into the spinning module 1, and adjust the temperature control device 2 of the spinning module to 70°C , kept constant for 20 minutes to heat the polymer evenly, wherein the distance from the spinneret of the spinneret to the receiving substrate was 15 cm, and the applied voltage was 60 kV.

Step 4: Turn on the high-voltage power supply, adjust the voltage to 60kV, and spin the ambient temperature at 25°C and the humidity at 60%, electrospin the polymer solution onto the receiving substrate 3 at a perfusion rate of 5mL/h, and at the same time The liquid nitrogen constant-speed release device 5 installed in the receiving and transporting device 4 releases liquid nitrogen at a rate of 50L/min, and the instantaneous temperature of the spun nanofibers in contact with the liquid nitrogen drops below 0°C, and at the same time, the nanofibers are affected by the direction of movement. Opposite reaction force, so as to obtain a high-efficiency, low-resistance nanofiber electret filter material with no adhesion between fibers and a fluffy three-dimensional network structure. The nanofiber layer has a gram weight of 50g/m ² The surface electrostatic potential of the material is 4000V, and the hydrophobic angle is 152°. As shown in Figure 2, the spun nanofiber electret filter material has a filtration efficiency of 99.9991% for 0.006-1μm particles, and has excellent charge storage stability. The resistance is 19Pa, and the dust holding capacity is 2000g/m ² .

Example 2

An electrospun nanofiber electret filter material and a preparation method thereof, the specific steps are:

Step 1: Place the polybutylene terephthalate particles in a vacuum oven at 50° C. for 1 hour to vacuum dry.

The second step: add boehmite to a certain amount of dichloromethane, and ultrasonic for 4 hours, then add the dried polybutylene terephthalate particles into the dichloromethane solvent containing boehmite, and dissolve the above solution Place on a magnetic stirrer and stir for 12 hours respectively to form a homogeneous solution; in the homogeneous solution, the mass fraction of polybutylene terephthalate is 20%, and the boehmite content is the total amount of polymer and inorganic nanoparticles. 3wt% of the amount.

The third step: use the electrospinning equipment shown in Figure 1 to spin, first draw a certain amount of the above-mentioned polybutylene terephthalate polymer containing boehmite in the spinneret module 1 in the 10mL spinneret module solution, and adjust the temperature control device 2 of the spinneret module to 60°C for 20 minutes to heat the polymer evenly, wherein the distance from the nozzle of the spinneret module to the receiving substrate is 30cm, and the applied voltage is 50kV.

Step 4: Turn on the high-voltage power supply, adjust the voltage to 50kV, and spin the ambient temperature at 25°C and the humidity at 60%, electrospin the polymer solution onto the receiving substrate 3 at a perfusion speed of 5mL/h, and simultaneously The liquid nitrogen constant-speed release device 5 installed in the receiving and transporting device 4 releases liquid nitrogen at a speed of 60L/min, and the instantaneous temperature of the spun nanofibers in contact with liquid nitrogen drops below 0°C, and at the same time, the nanofibers are affected by the direction of their movement. Opposite reaction force, so as to obtain a high-efficiency, low-resistance nanofiber electret filter material with no adhesion between fibers and a fluffy three-dimensional network structure. The nanofiber layer has a gram weight of 61g/m ² . The surface electrostatic potential of the material is 3300V, and the hydrophobic angle is 158°. As shown in Figure 2, the spun nanofiber electret filter material has a filtration efficiency of 99.9994% for 0.006-1μm particles, and has excellent charge storage stability. The resistance is 12Pa, and the dust holding capacity is 2980g/m ² .

Example 3

An electrospun nanofiber electret filter material and a preparation method thereof, the specific steps are:

Step 1: Place the fluorinated polyurethane particles and the polyethersulfone particles in vacuum ovens at 70°C and 80°C for 2 hours, respectively, to dry in vacuum. The second step: add silsesquioxane to a certain amount of formic acid and DMF mixed solvent, and ultrasonic for 5 hours, then add the dried fluorinated polyurethane particles and polyethersulfone particles to formic acid and DMF containing silsesquioxane In the mixed solvent, the above solution was placed on a magnetic stirrer and stirred for 10 hours respectively to form a homogeneous solution; in the homogeneous solution, the mass fraction of fluorinated polyurethane and polyethersulfone was 20%, and the mixing ratio of the two was 1:4, the content of silsesquioxane is 3wt% of the total amount of polymer and inorganic nanoparticles.

The third step: use the electrospinning equipment shown in Figure 1 to spin, first pump a certain amount of the above-mentioned mixed solution of fluorinated polyurethane and polyethersulfone polymer containing silsesquioxane into the spinning module 1, and spray The temperature control device 2 of the silk module was adjusted to 80° C. and kept constant for 20 minutes to heat the polymer evenly. The distance from the nozzle of the spinning module to the receiving substrate was 35 cm, and the applied voltage was 65 kV. Step 4: Turn on the high-voltage power supply, adjust the voltage to 65kV, the ambient temperature of spinning is 20°C, and the humidity is 40%, electrospin the polymer solution onto the receiving substrate 3 at a perfusion speed of 6mL/h, and at the same time The liquid nitrogen constant-speed release device 5 installed in the receiving and transporting device 4 releases liquid nitrogen at a rate of 49L/min, and the instantaneous temperature of the spun nanofibers in contact with liquid nitrogen drops below 0°C, and at the same time, the nanofibers are affected by the direction of their movement. Opposite reaction force, so as to obtain a high-efficiency, low-resistance nanofiber electret filter material with no adhesion between fibers and a fluffy three-dimensional network structure. The nanofiber layer has a grammage of 66g/m ² . The surface electrostatic potential of the material is 2320V, and the hydrophobic angle is 154°. As shown in Figure 2, the spun nanofiber electret filter material has a filtration efficiency of 99.9999% for 0.006-1μm particles, and has excellent charge storage stability. The resistance is 7Pa, and the dust holding capacity is 3280g/m ² .

Example 4

An electrospun nanofiber electret filter material and a preparation method thereof, the specific steps are:

Step 1: Place the polyvinyl acetate particles and the nylon 6 particles in vacuum ovens at 30°C and 80°C for 3 hours to vacuum dry, respectively.

Second step: dissolve the dried polyvinyl acetate particles and nylon 6 particles in toluene and formic acid respectively, and place the above solutions on a magnetic stirrer to stir for 12 hours respectively to form a homogeneous solution; , the mass fraction of the mixed solution of polyvinyl acetate and nylon 6 is 20%, and the mixing ratio of the two is 4:1.

The third step: use the electrospinning equipment shown in Figure 1 to spin, first pump a certain amount of the above-mentioned polyvinyl acetate particles and nylon 6 polymer solution into the spinneret module 1, and adjust the temperature control device 2 of the spinneret module To 90°C, keep it constant for 20 minutes to heat the polymer evenly, wherein the distance from the spinneret of the spinneret module to the receiving substrate is 35cm, and the applied voltage is 55kV.

Step 4: Turn on the high-voltage power supply, adjust the voltage to 55kV, the ambient temperature of spinning is 20°C, and the humidity is 50%, electrospinning the polymer solution onto the receiving substrate 3 at a perfusion speed of 7mL/h, and at the same time The liquid nitrogen constant-speed release device 5 installed in the receiving and transporting device 4 releases liquid nitrogen at a speed of 60L/min, and the instantaneous temperature of the spun nanofibers in contact with liquid nitrogen drops below 0°C, and at the same time, the nanofibers are affected by the direction of their movement. Opposite reaction force, so as to obtain a high-efficiency, low-resistance nanofiber electret filter material with no adhesion between fibers and a fluffy three-dimensional network structure. The nanofiber layer has a grammage of 32g/m ² . The surface electrostatic potential of the material is 3860V, and the hydrophobic angle is 162°. As shown in Figure 2, the spun nanofiber electret filter material has a filtration efficiency of 99.9991% for 0.006-1μm particles, and has excellent charge storage stability. The resistance is 5Pa, and the dust holding capacity is 2980g/m ² .

Example 5

An electrospun nanofiber electret filter material and a preparation method thereof, the specific steps are:

Step 1: Dry the polyurethane particles, polyethylene oxide powder and polyethersulfone particles in a vacuum oven at 70°C for 3 hours.

The second step: add tourmaline to a certain amount of DMF solvent, and ultrasonic for 5 hours, then add the dried polyurethane particles, polyethylene oxide powder and polyethersulfone particles into the DMF solvent containing tourmaline, and place the above solution in Stir on a magnetic stirrer for 10 hours to form a homogeneous solution; in the homogeneous solution, the mass fraction of polyurethane, polyethylene oxide and polyethersulfone is 35%, and the mixing ratio of the three is 1:4:4. The content of stone is 3wt% of the total amount of polymer and inorganic nanoparticles.

The third step: use the electrospinning equipment shown in Figure 1 to spin, first pump a certain amount of the above-mentioned polyurethane particles containing tourmaline, polyethylene oxide and polyethersulfone polymer mixed solution into the spinning module 1, and spray The temperature control device 2 of the silk module was adjusted to 100° C. and kept constant for 20 minutes to heat the polymer evenly. The distance from the nozzle of the spinning module to the receiving substrate was 35 cm, and the applied voltage was 65 kV.

Step 4: Turn on the high-voltage power supply, adjust the voltage to 65kV, and spin the ambient temperature at 25°C and the humidity at 40%, electrospin the polymer solution onto the receiving substrate 3 at a perfusion rate of 4mL/h, and at the same time The liquid nitrogen constant-speed release device 5 installed in the receiving and transporting device 4 releases liquid nitrogen at a rate of 45L/min, and the instantaneous temperature of the spun nanofibers in contact with liquid nitrogen drops below 0°C, and at the same time, the nanofibers are affected by the direction of their movement. Opposite reaction force, so as to obtain a high-efficiency, low-resistance nanofiber electret filter material with no adhesion between fibers and a fluffy three-dimensional network structure. The nanofiber layer has a grammage of 67g/m ² . The surface electrostatic potential of the material is 3220V, and the hydrophobic angle is 164°. As shown in Figure 2, the spun nanofiber electret filter material has a filtration efficiency of 99.9998% for 0.006-1μm particles, and has excellent charge storage stability. The resistance is 5Pa, and the dust holding capacity is 3420g/m ² .

Example 6

An electrospun nanofiber electret filter material and a preparation method thereof, the specific steps are:

Step 1: Put the polyvinyl alcohol powder, fluorinated polyurethane particles and polyethylene oxide powder in a vacuum oven at 70° C. for 3 hours to vacuum dry.

Second step: dissolve the dried polyvinyl alcohol powder, fluorinated polyurethane particles and polyethylene oxide powder in DMF, place the solution on a magnetic stirrer and stir for 10 hours respectively to form a homogeneous solution; In the phase solution, the mass fraction of polyvinyl alcohol, fluorinated polyurethane and polyethylene oxide is 20%, and the mixing ratio of the three is 4:4:1.

The third step: use the electrospinning equipment shown in Figure 1 to spin, first pump a certain amount of the above-mentioned polyvinyl alcohol, fluorinated polyurethane and polyethylene oxide polymer solution in the spinneret module 1, and the temperature of the spinneret module The control device 2 was adjusted to 100°C and kept constant for 20 minutes to heat the polymer evenly. The distance from the nozzle of the spinneret module to the receiving substrate was 30cm, and the applied voltage was 40kV.

Step 4: Turn on the high-voltage power supply, adjust the voltage to 40kV, the ambient temperature of spinning is 28°C, and the humidity is 55%, electrospin the polymer solution onto the receiving substrate 3 at a perfusion speed of 3mL/h, and at the same time The liquid nitrogen constant-speed release device 5 installed in the receiving and transporting device 4 releases liquid nitrogen at a speed of 40L/min, and the instantaneous temperature of the spun nanofibers in contact with liquid nitrogen drops below 0°C, and at the same time, the nanofibers are affected by the direction of their movement. Opposite reaction force, so as to obtain a high-efficiency, low-resistance nanofiber electret filter material with no adhesion between fibers and a fluffy three-dimensional network structure. The nanofiber layer has a grammage of 55g/m ² . The surface electrostatic potential of the material is 4270V, and the hydrophobic angle is 159°. As shown in Figure 2, the spun nanofiber electret filter material has a filtration efficiency of 99.9997% for 0.006-1μm particles, and has excellent charge storage stability. The resistance is 11Pa, and the dust holding capacity is 2590g/m ² .

Embodiment 7-27 preparation steps are the same as embodiment 1, wherein solution parameters, process parameters and composite filter material performance parameters are as shown in table 1-2:

Table 1

Table 2

Embodiment 28-75 preparation steps are the same as embodiment 2, wherein solution parameters, process parameters and composite filter material performance parameters are as shown in table 3-6:

table 3

Table 4

table 5

Table 6

The preparation steps of Examples 76-97 are the same as in Example 3, and the preparation steps of Examples 98-99 are the same as in Example 4, wherein the solution parameters, process parameters and composite filter material performance parameters are as shown in Table 7-8:

Table 7

Table 8

Embodiment 100-109 preparation steps are the same as embodiment 5, and embodiment 109-110 preparation steps are the same as embodiment 6, wherein solution parameters, process parameters and composite filter material performance parameters are as shown in table 9:

Table 9

Claims (9)

1. a preparation method of electrospinning nanofiber electret filter material, is characterized in that comprising the following steps: 1) Electrospinning is performed after heating the polymer solution to 30-120°C; 2) The fiber obtained by electrospinning is quickly cooled to below 0° C. after being received by the receiving substrate, and the electrospun nanofiber electret filter material is obtained; the rapid cooling means that the distance between the spun nanofiber and the receiving substrate is less than When the thickness is 1mm, the nanofibers will drop below 0°C in less than 5s after contacting with liquid nitrogen; In the polymer solution, the polymer is polyvinylidene fluoride, polypropylene, polybutylene terephthalate, polyethylene terephthalate, polyarylate, polyvinyl acetate, nylon 6, polyvinyl alcohol , polymethyl methacrylate, polyaniline, polyethylene oxide, polyvinylpyrrolidone, polyacrylonitrile, polycaprolactone, polyethylene glycol, polyurethane, fluorinated polyurethane, polysulfone, polyethersulfone, polyvinylidene fluoride - One of hexafluoropropylene, polyvinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether, polyvinylidene fluoride-chlorotrifluoroethylene, or a mixture of any two or three polymers; where The solvent in the polymer solution corresponds to: Polyvinylidene fluoride: N,N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, triethyl phosphate and dimethyl sulfoxide; Polypropylene: n-heptane, tetrahydronaphthalene, xylene; Polybutylene terephthalate: dichloromethane, tetrahydrofuran (THF), chloroform, acetone; Polyethylene terephthalate: dichloromethane, tetrahydrofuran, chloroform, acetone; Polyarylate: dichloromethane, tetrahydrofuran, chloroform, acetone; Polyvinyl acetate: toluene, acetone, ethanol, acetic acid, ethyl acetate, chloroform; Nylon 6: formic acid; Polyvinyl alcohol: water, ethanol, N,N-dimethylformamide, tetrahydrofuran; Polymethyl methacrylate: chloroform, acetic acid, ethyl acetate, acetone, toluene; Polyaniline: N,N-dimethylformamide, N-methylpyrrolidone; Polyethylene oxide: N,N-dimethylformamide, ethanol, water, chloroform; Polyvinylpyrrolidone: water, ethanol, N,N-dimethylacetamide, N,N-dimethylformamide; Polyacrylonitrile: N,N-dimethylformamide, dimethylsulfoxide; Polycaprolactone: N,N-dimethylformamide, acetone; Polyethylene glycol: water, ethanol, N,N-dimethylformamide; Polyurethane: N,N-dimethylformamide, acetone, N-methylpyrrolidone; Fluorinated polyurethane: N,N-dimethylformamide, acetone, N-methylpyrrolidone; Polysulfone and polyethersulfone: N,N-dimethylformamide, acetone, N-methylpyrrolidone, dimethylacetamide, tetrahydrofuran; Polyvinylidene fluoride-hexafluoropropylene: N,N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, triethyl phosphate and dimethyl sulfoxide; Polyvinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether: N,N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, triethyl phosphate and dimethyl sulfoxide; Polyvinylidene fluoride-chlorotrifluoroethylene: N,N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, triethyl phosphate and dimethyl sulfoxide; The solvent used for the mixture of any two or three polymers above: a mixture of solvents that can dissolve a single polymer in the above solvents or a single solvent that can dissolve two or three polymers at the same time; The preparation process of the polymer solution is as follows: adding the polymer into the corresponding solvent, and continuously stirring for 3-20 hours with a magnetic stirring device. 2. The preparation method of a kind of electrospun nanofiber electret filter material according to claim 1, characterized in that, the mass concentration of the polymer solution is 3-40%. 3. the preparation method of a kind of electrospinning nanofiber electret filter material according to claim 1 and 2, is characterized in that, in described polymer solution, polymer comprises homopolymer, block copolymer, random Copolymers, mixtures of two different homopolymers, mixtures of homopolymers and block copolymers, and mixtures of homopolymers and random copolymers. 4. the preparation method of a kind of electrospinning nanofiber electret filter material according to claim 1, is characterized in that, also contains at least one inorganic nanoparticle in the described polymer solution, and described inorganic nanoparticle is carbon dioxide Silicon, aluminum oxide, zinc oxide, barium oxide, titanium dioxide, tantalum pentoxide, barium titanate, lead zirconate titanate, silicon nitride, tourmaline, boehmite, or silsesquioxane nanoparticles; the The added amount of inorganic nanoparticles is: 0.1-10wt% of the total amount of polymer and inorganic nanoparticles; Wherein, a magnetic stirring device is continuously stirred for 3-20 hours to prepare a uniform and stable solution. 5. the preparation method of a kind of electrospinning nanofiber electret filter material according to claim 1, is characterized in that, described heating refers to that polymer is heated in the spinneret module of electrospinning, promptly spinneret module connects A temperature control device; the spinning module also contains an online stirring device. 6. The preparation method of a kind of electrospinning nanofiber electret filter material according to claim 1, characterized in that, the process conditions of the electrospinning are: voltage 5-70kV, receiving distance 3-40cm, perfusion speed 0.1～10mL/h, temperature 0～35℃, relative humidity 0～90%. 7. the preparation method of a kind of electrospinning nanofiber electret filter material according to claim 1, is characterized in that, described receiving substrate is the fiber substrate of wood pulp cellulose substrate, fiber substrate or mixing; The wood pulp cellulose substrate is wood pulp cellulose filter paper or wood pulp cellulose nonwoven fabric with a stiffness of 0.5-5mN m and a grammage of 8-400g/m2. ^The wood pulp cellulose filter paper is corrugated filter paper, of which the cellulose The corrugated distance of corrugated filter paper is 0~3mm; The fiber substrate is filter paper or non-woven fabric containing cellulose fiber, polyester fiber, polyolefin fiber, its stiffness is 0.5-5mN·m, and its grammage is 6-350g/ ^m2 ; the fiber filter paper includes corrugated filter paper, of which The corrugation distance of cellulose corrugated filter paper is 0-3mm; The mixed fiber substrate is a filter paper or non-woven fabric containing mixed fibers composed of two or more of cellulose fibers, polyester fibers, and polyolefin fibers, with a stiffness of 0.5 to 5 mN·m and a grammage of 6 to 5. 350g/m ² , the mixed fiber filter paper is corrugated filter paper, wherein the corrugated distance of the cellulose corrugated filter paper is 0mm-3mm. 8. The preparation method of a kind of electrospinning nanofiber electret filter material according to claim 1, characterized in that, the mode of cooling is to set a liquid crystal at a distance of 1 to 100 mm from the back side of the receiving substrate. Nitrogen constant speed release device, the release speed is 1-100L/min. 9. According to the electrospun nanofiber electret filter material prepared by the preparation method described in any one of claims 1 to 8 above, it is characterized in that the electrospun nanofiber electret filter material is a substrate layer and a nanofiber layer The two-layer composite structure; the material of the substrate layer is porous wood pulp cellulose substrate, fiber substrate or mixed fiber substrate, the fiber diameter is 10-50 μm, and the pore size is 3-120 μm; the nanofiber layer Nanofiber diameter: 0.008-1 μm, nanofiber layer gram weight: 0.01-70g/m ² , nanofiber layer porosity ≥ 80%; the surface electrostatic potential of the electrospun nanofiber composite electret filter material is 800- 6000V, hydrophobic angle > 150°, the filtration efficiency of 0.006-1μm particles can reach more than 99.999%, the pressure resistance is less than 20Pa, and the dust holding capacity is 300-3600g/m ² .