SU503485A3 - A method of manufacturing a porous membrane - Google Patents

Description

(54) METHOD OF MAKING POROUS MEMBRANE

The concentration of the spreading solution is between 2 and 30, preferably between 10 and 20%.

In the process of obtaining this solution, the polymer may be dissolved in a solvent-non-solvent mixture. There are also options such as dissolving a polymer in a solvent, then introducing a non-solvent, or dissolving a polymer in part of a solvent or solvent-non-solvent mixture, then introducing the remaining amount of solvent with the addition of non-solvents (or the remaining amount of solvent-non-solvent mixture).

The dissolution of the polymer occurs usually at room temperature. However, it is possible to begin dissolution at a low temperature, for example, 3 to 20 ° C, and then raise the temperature to 50 to 70 ° C.

The membrane may be flat, tubular, spiral-shaped (the shape of the substrate on which the polymer solution spreads). Glass or a metal such as stainless steel is used as the material of this substrate. You can use the substrate and other materials.

The polymer can flow directly onto the substrate described above, to obtain reinforced membranes, the polymer can also be placed on the reinforcement, which in turn is fixed to the substrate. Typically, the reinforcement is a mesh, knitted fabric of natural or synthetic fibers.

Typically, the polymer spreads at room temperature. But you can carry out the operation, for example, at 10 - 70 ° C.

The contact of the produced film with the coagulating liquid must occur before evaporation of the diluent begins. Preferably, the film is immersed in a coagulation bath or the film is poured from the same bath during its formation. This technology is applicable when the process takes place in air. In accordance with the invention, the film is brought into contact with the coagulation bath less than 5 seconds after its ejection, the coagulation is carried out at 20 - 30 ° C in the absence of the solvent, the boiling point of which is 40 ° C or higher.

Other methods may be used to prevent evaporation of the diluent. The resulting film can be placed in an atmosphere saturated with diluent, at least between the time of pouring and the time it makes contact with the coagulation bath.

Example 1

A. Preparation of polyvinyltrimethylsilane

Vinyltrimethylsilane is distilled at room temperature (20-25 ° C) under pressure of mercury. Art. The distillate is collected in a vial cooled with liquid nitrogen. Then a solution of the catalyst is introduced into this vial, the vial is poured in and the polymerization is carried out first at room temperature and then at 35 ° C.

Butyl lithium dissolved in cyclohexane is taken as a catalyst. The amount of monomer used is 1400 g; the concentration of monomer in the reaction medium is 7 mol / l, the concentration of catalyst in the reaction medium is 0.93 10 mol / l; the polymerization time is 435 hours.

1070 g of polymer were collected; characteristic viscosity is 210 (25 ° C in cyclohexane).

B. Obtaining the membrane

115 g of the polymer described in section A is dissolved by agitation at 21 ° C in a mixture containing 550 g of monochlorobenzene and 240 g of isobutanol.

After complete dissolution within 1 hour and 30 minutes, stirring is stopped and the solution is left at rest for 1 hour to achieve its degassing, then filtered (solution of 128 N at 21 ° C).

The solution thus obtained is poured through a vertical spinneret onto a drum, the lower part of which is immersed in a methanol bath. The die is located at a distance of 0.2 mm

over the drum. The linear rotational speed of the latter is 30 cm / min. The coagulation of the polymer solution begins immediately with film formation due to a ramp allowing the solution to be poured with methanol as soon as it comes out of the die. The rotation of the drum then carries the film into the methanol bath, which has a temperature of 21 ° C.

The total coagulation time is 14 minutes.

Then the membrane is fed to cylinders having a temperature of 23 ° C, where it dries completely in 15 minutes. This membrane has a thickness of 100-110 microns. On each

On its side, it has pores with a diameter of 0.2-1 microns.

The membrane does not show any selectivity with respect to oxygen, carbon dioxide, hydrogen, or nitrogen, which indicates the presence of at least part of the pores that penetrate the entire thickness of the membrane.

The capacity of water at a pressure of 0.05 bar is 130 l / m per day. The capacity of this membrane is

air at a pressure drop of 1 bar is 100. h

Example 2. The process is carried out under the conditions described in Example 1, but with a solution made from 100 g of polyvinyltrimethylsilane (viscosity 180 / g); 550 g of monochlorobenzene and 240 g of isobutanol. The viscosity of the solution is 22 P at 21 ° C. The resulting membrane has the following characteristics:

Thickness, micron POE selectivity with respect to mixtures of gases O2, CO2, N2,

H2, non-null

Water flow capacity (0.05 bar), l / m - day 1730

Air flow capacity (1 bar), m / m - h300

Example 3. A solution (viscosity 66 P, 21 ° C) was prepared from 125 g of polyvinyltrimethylsilane from Example 2, 550 g of monochlorobenzene and 240 g of isobutanol.

The membrane is made according to the technology described in Example 1.

This membrane has the following properties:

Thickness, mkPO-120

Selectivity with respect to mixtures of gases O2, CO2, Na, HZ, HeNoleva

Water flow capacity (0.05 bar).

l / m - day

Air capacity (1 bar),

Example 4. A solution (viscosity 7 F, 21 ° C) of PO g polyvinyltrimethylsilane (intrinsic viscosity 150 cm g), 550 g monochlorobenzene, and 240 tons of isobutanol were prepared.

According to the technology described in Example 1, a membrane was fabricated with the following properties:

Thickness, mkm80

Surface porosity

(average diameter) 0.3 - 7

Selectivity with respect to mixtures of gases O2, COA, NOa, HZ, NENUleva

Capacity for water (0.05 bar).

8650

l / m-day Capacity for air (1 bar), m m-day

1200

Claims (1)

Invention Formula The method of making a porous membrane by coating a layer of a solution of polyvinyltrimethylsilane in a mixture of solvent (s) and non-solvent onto the anti-adhesive substrate, precipitating the polyvinyltrimethylsilane, drying and then separating the temporary substrate, used to use an anisotropic structure of pores through the thickness of the application, I used the used substrate. - 50 weight. % non-solvent, and precipitation is carried out at 20-30 ° C by wet coagulation in a non-solvent.