CN107299456A - A kind of composite nano-fiber membrane and its preparation method and application - Google Patents

Abstract

The invention discloses a composite nanofiber membrane and its preparation method and application, which are made of electrospun nanofiber deposited foaming material. Compared with the prior art, it has the following advantages: (1) The present invention adopts electrostatic spraying technology to prepare foamed particles or short foamed fibers, which are deposited on the surface of electrospun nanofibers to obtain a composite nanofiber film with controllable thickness, which improves nano The porosity, gas permeability, bulkiness of fiber film; (2) method of the present invention has improved the physical and mechanical properties such as impact load resistance, heat insulation, sound insulation and specific strength of nanofiber film; (3) the present invention The method reduces the pressure drop and resistance of the nanofiber membrane, and the preparation process is simple and the cost is low.

Description

A kind of composite nanofiber membrane and its preparation method and application

technical field

The invention belongs to the field of material chemistry, and relates to a nanofiber membrane with controllable thickness, in particular to a composite nanofiber membrane combined with electrospun nanofibers and foaming materials, and a preparation method and application thereof.

Background technique

Due to the characteristics of small fiber diameter, large specific surface area, strong adsorption capacity and high surface free energy, nanofibers are widely used in many fields. In terms of filtration, especially in air filtration, compared with traditional filter materials, nanofiber membranes have high specific surface area, high adsorption capacity, high adsorption capacity, small pore size, high barrier capacity, light weight and excellent air permeability. It has gradually become one of the research hotspots.

Traditional electrospun nanofibers have remarkable high-efficiency filtration characteristics, but studies have shown that general electrospun nanofiber membranes are relatively dense. Although the filtration performance is high, the pressure drop is relatively large, and the air permeability is not ideal, which also reduces The service life of the product limits its wide application in high-efficiency and low-resistance filter materials.

Chinese patent 201310459720.X discloses a nanofiber filter material, which prepares the nanofibers of the filter material into a three-dimensional crimped state, and forms natural folds to increase its bulkiness. At the same time, the electrospun nanofibers are combined with support materials such as gauze, mesh structure materials and non-woven fabrics. The support layer is one or more layers, or a sandwich sandwich support layer to improve the rigidity and strength of the material.

Chinese patent 201510009971.7 discloses a high-efficiency and low-resistance nanofiber air filter material for masks and its preparation method. The nanofiber layer with a uniform cylindrical shape and the nanofiber layer with a beaded structure are cyclically and alternately deposited on the receiving substrate by electrospinning. , to prepare a high-efficiency and low-resistance composite nanofiber filter material with a fluffy structure and a mesh-like interconnected structure with three-dimensional cavities.

Wang et al. (Wang Na, Si Yinsong, Wang Ni, Sun Gang, El-Newehy Mohamed, Al-Deyab Salem S., Ding Bin. Multilevel structured polyacrylonitrile/silicananofibrous membranes for high-performance air filtration. Separation and Purification Technology, 2014, 126(15):44–51.) Adding different amounts of silica nanoparticles to polyacrylonitrile solution for electrospinning, the addition of silica increased the surface roughness of the nanofibers and changed the cross-section of the fibers The shape increases the surface porosity of the nanofibers, thereby improving the filtration efficiency of the material and reducing the pressure drop.

Chinese patent 201410731856.6 discloses a method for preparing a porous sodium alginate nanofiber wound dressing material, which is to dissolve a thermally decomposed foaming agent as a porogen into the spinning solution in a certain proportion, and prepare nanofibers by means of electrospinning , and then heat treatment at a certain temperature to decompose the foaming agent, making the inside and surface of the fiber porous.

In the above prior art, although the aforementioned several examples have increased the fluffy degree of the nanofiber membrane to a certain extent, reduced the pressure drop of the fiber membrane, and improved the air permeability of the material, but the process is relatively cumbersome, the efficiency is relatively low, and the cost is high. . The method of dissolving the porogen in the spinning solution described later will destroy the structure of the nanofibers and is not widely applicable. Based on the advantages and disadvantages of the above-mentioned electrospun nanofiber membrane filter materials, it is necessary to develop a method that can endow the nanofiber membrane with high filtration efficiency and low filtration resistance, and at the same time, the preparation process is simple and the cost is low.

Contents of the invention

The technical problem to be solved: In order to overcome the defects of the prior art, endow the nanofiber membrane with high filtration efficiency and low filtration resistance, and at the same time, the preparation process is simple and the cost is low. The present invention provides a composite nanofiber membrane and its preparation method and application.

Technical solution: a composite nanofiber membrane made of electrospun nanofiber deposition foaming material; the foaming material is polystyrene, polymethyl methacrylate, polyurethane, polytetrafluoroethylene, polyvinyl chloride, At least one of polyvinyl alcohol, polyethylene, phenolic, polypropylene, polycarbonate, polyester, polyamide, collagen and chitosan.

Preferably, the foamed material prepared by electrostatic spraying is deposited between the electrospun nanofibers in the form of microspheres or short fibers, so as to increase the distance and pores between the nanofibers.

The preparation method of described a kind of composite nanofibrous membrane comprises the following steps:

Step 1, preparation of electrospinning solution: dissolving the high polymer in a solvent with good volatility to make a homogeneous solution with a mass fraction of 8% to 20%;

Step 2, preparation of electrostatic spray solution: dissolve the foaming material in the liquid foaming agent, the liquid foaming agent is at least one of low boiling point hydrocarbons, aliphatic hydrocarbons, aromatic hydrocarbons and alcohols, ketones, ethers, and aldehydes , and then the inorganic salt is dispersed in the above-mentioned solution, and the inorganic salt is sodium carbonate, sodium bicarbonate, calcium carbonate or calcium bicarbonate;

Step 3, preparation of composite nanofiber membrane: place the electrospinning solution prepared in step 1 in the syringe (3) for electrospinning, and place the electrostatic spray solution prepared in step 2 in the syringe (2) for electrostatic spraying ; Wherein the inner diameter of the needle of the syringe (3) for electrospinning is 0.3-0.7mm, the inner diameter of the needle of the syringe (2) for electrostatic spraying is 0.3-1.0mm, the working voltage is 16-25kV, the receiving distance is 16-30cm, the electrostatic The advancing speed of the spinning syringe (3) is 0.3-1.0mL/h, and the advancing speed of the electrostatic spraying syringe (2) is 0.5-2.0mL/h;

Step 4, post-treatment of the composite nanofiber membrane: heating or placing in an acidic solution such as HCl, glacial acetic acid, dilute sulfuric acid, etc. for reaction to generate gas.

Preferably, in the third step, the injector (3) for electrospinning and the injector (2) for electrostatic spraying operate simultaneously.

Preferably, there is at least one injector (2) for electrostatic spraying.

The application of the composite nanofiber membrane in high-efficiency and low-resistance filter materials.

The application of the composite nanofiber membrane in sensor skeleton material.

Beneficial effects: (1) The present invention adopts electrostatic spraying technology to prepare foamed particles or short foamed fibers, and deposits them on the surface of electrospun nanofibers to obtain a composite nanofiber film with controllable thickness, which improves the porosity and air permeability of the nanofiber film , bulkiness; (2) method of the present invention has improved physical and mechanical properties such as impact load resistance, heat insulation, sound insulation and specific strength of nanofiber film; (3) method of the present invention has reduced nanofiber The pressure drop and resistance of the membrane are low, and the preparation process is simple and the cost is low.

Description of drawings

Fig. 1 is the structural representation of electrospinning electrostatic spray device;

Among them, 1 is a receiving drum, 2 is a syringe for electrostatic spraying, 3 is a syringe for electrospinning, and 4 is a high-voltage power supply.

Fig. 2 is a scanning electron micrograph of PA6/PAN composite nanofiber prepared by electrospinning-spray combination method.

detailed description

The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, the modifications and substitutions made to the methods, steps or conditions of the present invention all belong to the scope of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

Example 1

A composite nanofiber membrane is made of electrospun nanofiber deposition foaming material; the foaming material is polyvinyl alcohol.

A method for preparing a composite nanofibrous membrane, comprising the following steps:

Step 1, preparation of electrospinning solution: dissolving polyamide-6 in formic acid solution, stirring mechanically at a speed of 200 r/min for 10 h at room temperature to prepare a solution with a mass fraction of 20%, and standing to remove air bubbles;

Step 2. Preparation of electrostatic spray solution: Dissolve 0.4g polyacrylcyanide in 19.6g N,N-dimethylformamide, stir well to dissolve, add 0.5g sodium bicarbonate, stir ultrasonically, fully disperse, and let stand to remove Bubble;

Step 3, preparation of composite nanofiber membrane: the electrospinning solution prepared in the first step is placed in the syringe 3 for electrospinning, and the electrostatic spray solution prepared in the second step is placed in the syringe 2 for electrostatic spraying; The inner diameter of the needle of the syringe 3 for silk is 0.5mm, the inner diameter of the needle of the syringe 2 for electrostatic spraying is 0.7mm, the working voltage is 25kV, the receiving distance is 20cm, the advancing speed of the syringe 3 for electrospinning is 0.3mL/h, and the inner diameter of the needle for electrostatic spraying is 0.7mm. The advancing speed of syringe 2 is 1.0mL/h; the two syringes operate simultaneously;

Step 4, post-treatment of the composite nanofiber membrane: place the composite nanofiber membrane prepared in the third step in a vacuum drying oven for 24 hours, and then use a blast drying oven at 80°C for 24 hours to heat treat the spray particles. Foaming, so that the volume of the particles changes, and a polyamide-6 composite nanofiber membrane with a fluffy structure can be obtained.

As shown in Figure 2, electron microscopy scanning of PA6/PAN composite nanofibers prepared by electrospinning-spray combination method shows that the nanofiber membrane has high porosity, good air permeability and good bulkiness.

Example 2

A composite nanofiber membrane is made of electrospun nanofiber deposition foaming material; the foaming material is polyethylene.

Step 1, preparation of electrospinning solution: dissolve polyacrylonitrile in dimethylformamide solution, mechanically stir at a speed of 600r/min at room temperature until completely dissolved, make a solution with a mass fraction of 10%, and let it stand remove air bubbles;

Step 2, preparation of electrostatic spray solution: Dissolve polyethylene in toluene under a water bath condition of at least 70°C, prepare 20 g of electrostatic spray solution with a mass fraction of 3%, let it stand for defoaming, add 0.2 calcium carbonate after cooling, Ultrasonic stirring until uniform dispersion;

Step 3, preparation of composite nanofiber membrane: the electrospinning solution prepared in the first step is placed in the syringe 3 for electrospinning, and the electrostatic spray solution prepared in the second step is placed in the syringe 2 for electrostatic spraying; The inner diameter of the needle of the syringe 3 for silk is 0.5mm, the inner diameter of the needle of the syringe 2 for electrostatic spraying is 0.5mm, the operating voltage is 16kV, the receiving distance is 20cm, the advancing speed of the syringe 3 for electrospinning is 0.8mL/h, and the inner diameter of the needle for electrostatic spraying is 0.5mm. The advancing speed of syringe 2 is 1.0mL/h; the two syringes operate simultaneously;

Step 4, post-treatment of the composite nanofiber membrane: the composite nanofiber membrane prepared in the third step is immersed in a 1mol/L HCl solution for 1 hour, so that calcium carbonate and hydrochloric acid react to generate gas to form bubbles.

Claims (7)

1. a kind of composite nano-fiber membrane, it is characterised in that be made up of electrostatic spinning nano fiber deposition expanded material；The foaming Material is polystyrene, polymethyl methacrylate, polyurethane, polytetrafluoroethylene (PTFE), polyvinyl chloride, polyvinyl alcohol, polyethylene, phenol At least one of aldehyde, polypropylene, makrolon, polyester, polyamide, collagen and chitosan.

2. a kind of composite nano-fiber membrane according to claim 1, it is characterised in that the foaming material prepared by electrostatic spray Material is deposited in the way of microballoon or chopped fiber between electrostatic spinning nano fiber, to increase the distance between nanofiber and hole Gap.

3. the preparation method of a kind of composite nano-fiber membrane described in claim 1, it is characterised in that comprise the steps of：

It is prepared by the 1st step, electrostatic spinning solution：High polymer is dissolved in the good solvent of volatility, it is 8% that mass fraction, which is made, ~20% uniform solution；

It is prepared by the 2nd step, electrostatic spray solution：Expanded material is dissolved in liquid blowing agent, the liquid blowing agent is low boiling Inorganic salts, are then scattered in above-mentioned solution by least one of hydrocarbon, aliphatic hydrocarbon, aromatic hydrocarbon and alcohol, ketone, ether, aldehyde, described Inorganic salts are sodium carbonate, sodium acid carbonate, calcium carbonate or calcium bicarbonate；

It is prepared by the 3rd step, composite nano-fiber membrane：Electrostatic spinning solution prepared by the 1st step is placed in electrostatic spinning syring (3) In, electrostatic spray solution prepared by the 2nd step is placed in electrostatic spray syringe (2)；Wherein electrostatic spinning syring (3) Syringe needle internal diameter is 0.3~0.7mm, and the syringe needle internal diameter of electrostatic spray syringe (2) is 0.3~1.0mm, operating voltage is 16~ 25kV, it is 16~30cm to receive distance, and electrostatic spinning syring (3) fltting speed is 0.3~1.0mL/h, and electrostatic spray is used Syringe (2) fltting speed is 0.5~2.0mL/h；

4th step, composite nano-fiber membrane post processing：Heat or be placed in the acid solutions such as HCl, glacial acetic acid, dilute sulfuric acid and carry out instead Gas should be produced.

4. a kind of preparation method of composite nano-fiber membrane according to claim 3, it is characterised in that electrostatic in the 3rd step Spinning is run simultaneously with syringe (3) and electrostatic spray syringe (2).

5. a kind of preparation method of composite nano-fiber membrane according to claim 3, it is characterised in that the electrostatic spray It is at least one with syringe (2).

6. application of the composite nano-fiber membrane in efficient low-resistance filtering material described in claim 1 or 2.

7. application of the composite nano-fiber membrane in sensor framework material described in claim 1 or 2.