SU524821A1 - The method of obtaining polymer membranes - Google Patents

Description

(54) METHOD FOR OBTAINING POLYMERIC MEMBRANE POLYMER can be applied to the substrate, laid on a tape or a drum before the spinneret. The substrate can be used mesh, fabric materials, cardboard, porous cermet tape, etc. The polymer solution is applied at C, but the temperature may deviate from the indicated limits. Contact of the cast film with the solvent in the bath can be done without prior evaporation of the solvent from the film and with preliminary evaporation. During the coagulation process, solvents are washed out of the film, and it passes from the gelatinous to the solid pori membrane. This treatment is carried out to the maximum removal of the solvent from polymer solution. The coagulation process of most polymers is carried out at a normal temperature (20-25 ° C, but it can be carried out and npi at another temperature below the boiling point of the polymer solvents in the gap between the boiling point and the freezing point of the solvent in the bath. Increasing pore formation in the film in the process of wet forming from a polymer solution occurs at an ultrasound intensity of 0.8-1.6 W / cmH Above 1.6 W / s

Table 1 appears on the film microcracks and through holes, t, e, the diffusion layer of the film begins to break down. The pore frequency is also affected by the frequency of ultrasonic vibrations. Taking into account the mechanism of cavitation effects of ultrasound, as well as the most common series of ultrasonic generators produced in the USSR and abroad, the ultrasonic oscillation frequency is 5.8 and 20 kHz. The pore size D depends on the frequency M and t is the intensity of radiation H and is associated with them by empirical dependence. D KMN, where i K is a coefficient depending on the physicomechanical properties of the polymer. For peks of polyvinyltrimethylsilane K 1 O-11, for polyamide K 8-8.7; for Auertshnenntono language 14-14,8. The pore diameter was measured using an electron microscope as well as a Pore device designed to determine the porosity of a film by measuring the pressure required for air to pass through the steepest pores of a sample impregnated with kerosene. The dependency is illustrated in Table 1,

Polivshiltrimetilsilanov film 20 20

Polyamide film 8-8,74,8

8-8,78,0

8-8,720

4.8

7.2 8.0 80 160

destruction of the surface layer

57-60 64,128

Cellulose acetate 14-14,84,8

14-14,88,0

14-14,820

14-14,88,0

Note. Film thickness 200 microns.

 ly Usually | an increase in temperature does not lead to an acceleration of coagulation. For I nensification of mass transfer and fi ouecca coagulation, the film is acted upon (ultrasonic vibrations. In order to adjust the pore size, selectivity and gas permeability, the intensity and frequency of ultrasonic vibrations are changed. The source of ultrasonic vibrations can affect the film through the surface, on which is applied by the solution of: LIMER, through the precipitator washing the membrane in the precipitating bath, and simultaneously through the surface, and the precipitator. The finished membrane is removed from BaHHbr: dried by heated air Example 1. A method of obtaining porous memsPra from a solution of polyvinyltrimethyl silane; a) Preparation of polyvinyltrimethylsilane; Vinyltrimethylsilane is distilled at room temperature (20-25 ° C) under a pressure of 1 mm Hg. Art., distillate is collected in an ampoule cooled with liquid nitrogen. Then the catalyst solution is introduced into the ampoule, sealed, and polymerization is carried out at 1H room temperature by further raising the temperature to 35 ° C. Butyllithium dissolved in cyclohexane is taken as a catalyst. The amount of monomer used is 140 O g. The monomer concentration in the reaction medium is 7 mol / L; The concentration of catalyst in the reaction medium is 0.93 x 1O mol / l,

6

Continued table. one

101 112 224

destruction of the surface layer

20 Polymerization duration 510 hours. The collected polymer (107 O g) has an intrinsic viscosity of about 2 South / cm in cyclohexane at 25 ° C, b) Obtaining a membrane, i 115 g of the polymer obtained is dissolved by stirring at 21 ° C in a mixture , co (holding; 550 g of monochlorobenzene and 24O g; Isobutanol. After complete dissolution, stirring is stopped and the solution is left in a state of rest for 1 h to degasify the JTBopa. vertical: die on rotating drum, the lower part of which is immersed in a bath with methyl alcohol. The die is located 0.4 mm in riia above the drum, Circle | on CKojpocTb of the drum 1 m / min. The coagulation of the solution starts immediately upon leaving the filter nozzle thanks to a ramp allowing the solution to be irrigated with methanol. Rotation of the bar; The emitter of ultrasonic vibrations | is mounted in the wall of the bath. The parameters (intensity and frequency) are fixed on secondary devices installed on a wide-range ultrasonic generator. The total length of the abbot. MembiInf l in the occupational zone with. Is ready

The verified membrane is removed from the boulder, dried with hot air and thrown into rolls on a winding device.

The resulting membrane is 20 microns thick; It has pores with a diameter of 8x10 µm (at an hour: 5 o the 8 kHz and the radiation intensity of 1 W / cm). | The presence of squilled pores on the film also suggests that the membrane does not exhibit any selectivity with respect to gamma selected from grut; oxygen | nitrogen, hydrogen and carbon dioxide.

Capacity for water, meas; renna under pressure of 0.05 atm, is equal to;

38OQ. Capacity for air i at a pressure drop of 1 atm j 15 (pressure before and after the membrane); Rana 72O.

The preparation of membranes and the method of regupiro-ivani pore size for polyamide and acetyl-j cellulose are similar to the previous ones.

Note 2. A method for the preparation of asym-i metric membranes from a solution of polyvinyl-t and p-methyl a.

The filtered solution is popvinyltri-; MEtilsilan prepared according to tech. 25 of Example 1, from a crushing vessel, is fed by a dosing pump through a vertical die to a rotating drum, the lower part of kpTOppro is immersed in a bath with precipitator - methadol alcohol. The speed of the drum is 30 sherry 0.6 m / min .

The die is located at a distance of ~ 4 mm below the drum. The area from the spinneret to the place of immersion in methyl alcohol film 35 ka rokhodit in air at 23 ° C and part of the solvent evaporates from its outside; At the same time, a dense solidified layer is obtained on the surface of the film, which has a high selectivity of 40 relative gases such as oxygen and nitrogen) | helium carbon dioxide gas

The process of coagulation of the membrane begins immediately after the film is conjugated with the precipitation of the jttnH acceleration of the process of forming the membrane 45 and is affected by ultrasonic vibrations on the surface of the drum and precipitates the fir-tree washing the membrane

The processing time of the membrane in the bath 45 s. The finished cured membrane is removed from the bath of SO, dried with heated air and rolled into rolls on a winding device. The total thickness of the membrane is 180 microns. The volume of porosity is 67% of the total volume of the membrane, 65

Unlike the membranes described in example 1, the creeped membranes have a high selectivity with respect to gases such as oxygen, nitrogen, carbon dioxide, helium.

Measurement method 3, Method for producing flat m, embral from acetylcellulose solution

a) Obtaining a film-forming solution.

The preparation process from cellulose cellulose involves mixing the components, cleaning them from mechanical impurities (filtering deaeration, The film-forming solution contains (weight,%) 25 cellulose acetals with a molecular weight of 40,000, 30 forformamide, 45 acetone. All listed components are moved within 2O- 30 min. B) Membrane preparation,

A filter of Acetylcellulose solution is fed by a dosing pump through a vertical spinneret onto a rotating drum. The Niasn part of which is immersed in water. Watering solution temperature 20, water temperature 2 C, Exposure in water for 20 minutes. The process of coagulation of the membrane begins immediately when the film comes into contact with the precipitator (water). To regulate the process of forming the membrane, it is affected by ultrasonic vibrations on the surface of the drum and the precipitator. The rotation speed of the drum is 0.8 m / min, the finished cured membrane is taken out of the bath with the JC sensor in the heat-fixing bath. Heat treatment of cryogenic acids at 65 ° C for 10 min. Flat membranes from acetylcellulose solution were tested in special cells at a pressure of 100 kgf / cm with an NaCfc solution with a tracy of 20 g / l,

, - ..; have ..

Tests have shown that the HMIS membrane has the following parameters:

Water permeability l / m-h70

Sole retention% 92.46

Stress at break

(lengthwise), kgs94,6

The heat treatment of semi-permeable acetylcellulose membranes for reverse osmosis is the final processing step.

Example 4, A method for preparing porous membranes from a polyamide solution,

a) Obtaining film-forming solution

; ra ,,. . ,,,

The process of preparing a film-forming solution from polyamide includes smearing of the components, cleaning from mechanical PEMES (filtration) and deaeration,

The remaining film-forming solution contains 20% by weight of polyamide with a molecular weight of 23,000 and VO by weight,% of organic solvents. All of the listed Componex are mixed for 50-6O minutes at 20 ° C. b) Preparation of the Membrane; Filter of the bath ft. the thief of the polyamide passes through the deaeration stage for 24 hours. The solution temperature is 21 s. From the nutrient vessel, the polymer solution is metered into the pumping dosing unit into a flat-gap spreading die on the moving drum surface, the lower part of which is immersed in distilled water. The rotation of the drum carries the film into the water bath, the temperature of which is 21 ° C. The die plate is located at a distance of 0.7 mm above the drum. Linear speed of the drum shaft, 0.6 m / min. The process of precipitation (leaching of solvents in water) tta is detected immediately upon contact of the film with water. The total duration of the membrane precipitation process in water is 20 min; The drain from the spinneret to the place of immersion in distilled water, the film conducts in accordance with the spirit and part of the solvent evaporates from its outer side. In the process of deposition, the membranes are washed away with solvents, and it turns from a gelatinous to a solid-porous membrane. This treatment is carried out up to the maximum removal of solvents from Mem1 branes, in order to regulate the porosity of the membrane and speed up the process of leaching of the races. The solvents in the bath are affected by ultrasonic vibrations on the membrane, the frequency and amplitude of which is regulated. Ultrasonic vibrations affect the precipitator washing the membrane in the sedimentation bath or the surface onto which the polyamide solution is applied; The Wellsden membrane is ready to be pulled out; from the bath, dried with a pre-warmed spirit and rolled into rolls on the winding device. The resulting membrane has a thickness of 140 µm, on both sides of the membrane there are: pores with a diameter of 0.15-0.20 µm. Part i visible on the surface of the pores intersects the entire thickness of the membrane, the size of the pores allows; use a membrane to separate the nie: co-molecular compounds. The throughput capacity for water, measured inoa with a yield of 0.05 atm, is equal to 120 O l / m per day,; The capacity for air at a pressure drop of 1 Ytm (pressure of | Leni before and after the membrane) is 278 hours. (Mechanical strength of the membrane is kg / cm; Comparative data on the time of | Iram of the polyamide membrane precipitated without influence and with (st; by ultrasound, and the basic properties of the brane are given in table 2,

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Claims (1)

The formula of the invention is that with the purpose: the regulator of the pore pore in The method of obtaining polymeric membrane membranes, the formation is carried out under the molding of the polymer solution in the precipitator-action of ultrasonic vibrations at This is followed by a drying-intensity of ultrasound, 6 W / cm film, characterized by j and a frequency of 4.8-20 kHz,