CN108939942A - A kind of preparation method of composite membrane - Google Patents

Abstract

The invention discloses a preparation method of a composite membrane, which comprises the following steps: using a fiber grinder to grind polypropylene electret in a tert-butanol solution; using electrostatic spinning equipment to spin the polyacrylonitrile solution, using tert-butanol butanol solution, and continuously drip the dispersion liquid containing polypropylene electret; freeze-dry the prepared polyacrylonitrile nanofiber containing polypropylene electret; obtain polyacrylonitrile/polypropylene electret composite membrane. The process of the invention is relatively simple, the thickness of the obtained composite membrane is controllable, and the polarized property of the polypropylene electret is retained, which can be used for air filtration.

Description

A kind of preparation method of composite film

technical field

The invention belongs to the technical field of membrane material preparation, and in particular relates to a preparation method of a composite membrane.

Background technique

Through the electrospinning technology, the polymer solution can be continuously sprayed out of the nano-scale fiber under the action of voltage, so that it has ultra-fine pore size, ultra-high specific surface area, porosity and surface adsorption, fine particles, It is easily blocked and adsorbed by fibers, and has better filtration performance than traditional filter materials under the same pressure. Moreover, the diameter of the nanofiber is very small, and the resistance generated when the gas flows over the nanofiber will be reduced. Due to these unique characteristics of electrospun nanofibers, many researchers have paid attention to them.

Electret has bulk charge characteristics, that is, its charge is different from triboelectricity, and it appears on the surface of the electret as well as inside it. Melt-blown polypropylene electret non-woven fabrics can not only intercept the flowing dust in the gas through general inertial deposition, gravity deposition, Brownian diffusion and other mechanical action mechanisms, but also realize the purification of air and common It can kill bacteria and viruses, therefore, it has the characteristics of low resistance, high efficiency, dust removal and sterilization, and is expected to become the air purification material with the best filter resistance performance, so it has attracted widespread attention.

Although polypropylene electret non-woven fabric has good air filtration performance, it has disadvantages such as large negative pressure and low porosity, which are limited in the application of portable masks and the like, and the dust load is limited. In practical application, it needs to be replaced frequently, and these shortcomings hinder its development in the field of air filtration.

Contents of the invention

The purpose of the present invention is to solve the disadvantages of existing polypropylene electret non-woven fabrics such as large negative pressure and small loading capacity, and to provide a preparation method for a composite membrane. The composite membrane has a relatively high porosity and can effectively Absorbs dust in the air.

In order to achieve the above object, the invention discloses a method for preparing a composite membrane, comprising the following specific steps:

Step 1: Use a fiber pulverizer to pulverize and disperse the polypropylene electret non-woven fabric in a tert-butanol solution until the dispersion is uniform and without stratification;

Step 2: Add the polyacrylonitrile precursor into the N,N dimethylformamide solution, stir until the solution is uniform and clear, and then centrifuge to remove the bubbles in the solution;

Step 3: Use electrospinning equipment to spin the polyacrylonitrile solution prepared in step 2, use tert-butanol solution to undertake, and instill the polyacrylonitrile solution prepared in step 1 into the tert-butanol solution during spinning. Propylene electret dispersion;

Step 4: The polyacrylonitrile nanofibers containing polypropylene electret prepared in step 3 were left to stand for 12 hours, and freeze-dried to obtain a polyacrylonitrile/polypropylene electret composite film.

Preferably, in the step 1, the mass fraction of the tert-butanol solution is 66.7%, and the mass volume fraction of the electret is 1%-5%.

Preferably, the mass volume fraction of polyacrylonitrile in step 2 is 15%.

Preferably, the dropping rate of the polypropylene electret dispersion in step 3 is 1-2 drops/second.

Preferably, the electrospinning conditions in step 3 are: voltage 15kV, receiving distance 12cm, solution flow rate 1.0ml/h, needle 21.

Preferably, in step 4, the polyacrylonitrile nanofibers containing polypropylene electret are left standing in the tert-butanol solution.

Compared with the prior art, the present invention has the following significant advantages:

(1) The technique of the present invention is simple, and raw material is easy to get.

(2) The composite membrane prepared by the present invention has large specific surface area, high porosity and strong loading capacity.

(3) The prepared composite membrane combines the advantages of nanofiber and electret, and enhances the electrostatic adsorption capacity of the nanofiber membrane.

Description of drawings

Fig. 1 is the polyacrylonitrile/polypropylene electret composite film that the present invention makes.

Fig. 2 is a scanning electron micrograph of the polyacrylonitrile/polypropylene electret composite film prepared in the present invention.

Detailed ways

The present invention will be further clarified below in conjunction with specific embodiments and accompanying drawings.

Example

First, the polypropylene electret non-woven fabric is pulverized and dispersed in a tert-butanol solution by using a fiber pulverizer until the dispersion liquid is uniform without delamination. Subsequently, 1.5 g of polyacrylonitrile was dissolved in 10 ml of N,N dimethylformamide with a mass fraction of 15%, magnetically stirred until the solution was clear and uniform, and then centrifuged at a speed of 1000 r/min to remove air bubbles in the solution. The prepared polyacrylonitrile solution is spun by electrospinning equipment, and then carried out by tert-butanol solution, and the polypropylene electret dispersion is dripped into the tert-butanol solution during the spinning process. The prepared polyacrylonitrile nanofiber containing polypropylene electret was left to stand for 12 hours, and then freeze-dried to obtain a polyacrylonitrile/polypropylene electret composite film.

Claims (6)

1. a preparation method of composite membrane, is characterized in that, comprises following concrete steps: Step 1: Use a fiber pulverizer to pulverize and disperse the polypropylene electret non-woven fabric in a tert-butanol solution until the dispersion is uniform and without stratification; Step 2: Add the polyacrylonitrile precursor into the N,N dimethylformamide solution, stir until the solution is uniform and clear, and then centrifuge to remove the bubbles in the solution; Step 3: Use electrospinning equipment to spin the polyacrylonitrile solution prepared in step 2, use tert-butanol solution to undertake, and instill the polyacrylonitrile solution prepared in step 1 into the tert-butanol solution during spinning. Propylene electret dispersion; Step 4: The polyacrylonitrile nanofibers containing polypropylene electret prepared in step 3 are left to stand and freeze-dried to obtain a polyacrylonitrile/polypropylene electret composite film. 2. The preparation method of a kind of composite membrane as claimed in claim 1, is characterized in that, in step 1, the mass fraction of tert-butanol solution is 66.7%, and the mass volume fraction of electret is 1%～5%. 3. The preparation method of a kind of composite membrane as claimed in claim 1, is characterized in that, the mass volume fraction of polyacrylonitrile is 15% in step 2. 4. The preparation method of a kind of composite membrane as claimed in claim 1, is characterized in that, the drip rate of polypropylene electret dispersion liquid in step 3 is 1～2 drop/second. 5. The preparation method of a kind of composite membrane as claimed in claim 1, it is characterized in that, in step 3, electrospinning condition is: voltage 15kV, receiving distance 12～15cm, solution flow rate is 1.0ml/h, needle head is The 21st. 6. the preparation method of a kind of composite membrane as described in claim 1 is characterized in that, the polyacrylonitrile nanofiber containing polypropylene electret in step 4 is left standstill in tert-butyl alcohol solution, and stand time is 12 hours.