KR101200366B1 - Mass fabrication method of asymmetric gas separation hollow fiber membranes having high selectivity and permeability - Google Patents

Abstract

The present invention relates to a method for producing a hollow fiber membrane added with an inorganic additive, and more specifically to the hollow fiber membrane production method using a gas-selective polymer, a first solvent and a second solvent in addition to the addition of an inorganic additive to the hollow By producing a desert, gas permeability and selectivity are significantly improved, so it is applied to gas separation such as recovery of biomethane and hydrogen sulfide, recovery of greenhouse gases such as carbon dioxide, enrichment of oxygen, high purity of nitrogen, and hydrogen purification of petrochemical. It can be usefully used for the production of hollow fiber membranes of possible asymmetric structures.

Description

Mass fabrication method of asymmetric gas separation hollow fiber membranes having high selectivity and permeability

The present invention relates to a mass production method of a high permeability gas separation hollow fiber membrane having an asymmetric structure capable of selectively separating carbon dioxide, oxygen, hydrogen sulfide, water vapor and the like in a mixed gas.

Membranes using polymers must have good thermal, chemical and mechanical stability, high gas permeability and high selectivity in order to be applied to industrial applications. The gas permeability is the rate at which the gaseous permeable material permeates through the membrane and the selectivity is defined as the ratio of the permeation rate between two different components.

In general, however, the permeability and selectivity of polymer membranes tend to be inversely proportional to each other. In the case of gas separation, glassy polymers having high attraction force between polymer chains are generally used. In this case, gas permeability is low but relatively high selectivity can be expected. Accordingly, the separation membrane may be referred to as having an asymmetric structure or a composite membrane. Among them, especially asymmetric hollow fiber membranes have the highest membrane area per unit volume and have been commercialized after much research.

In the conventional method of producing asymmetric hollow fiber membranes, the key is to make the selective layer where the actual separation takes place outside of the hollow yarn without defects such as pinholes, and to make the lower layer porous while maintaining the mechanical strength of the support layer. .

US Patent No. 4,880,441 discloses a production method for forming a porous skin structure by inducing a spinning solution unstable by adding an acid-based additive capable of forming a high boiling point solvent and an acidic acid complex used to prepare a polymer solution. have.

U. S. Patent No. 5,795, 920 discloses a method for producing hollow fiber membranes through a combination of solvent / cosolvent / nonsolvent pairs and a change in composition.

US Patent No. 4,902,422 discloses a method for preparing an asymmetric hollow fiber membrane having a dense skin (selection) layer on the outside by mixing a high boiling point solvent with a low boiling point volatile additive and increasing the evaporation time of the solvent under reduced pressure. It is.

However, most of the hollow fiber membranes produced by the above-described production method use organic acid additives having poor solubility in polymers or low-boiling non-solvent additives, so that the spinning solution is uniformly prepared or the spinning solution composition is uniform. It is difficult to remove the generated air bubbles, and it is difficult to store the radiopharmaceutical for a long time, and in particular, the selective separation layer is too thick due to excessive external surface solvent evaporation during the spinning process, which makes it difficult to simultaneously increase gas selectivity and permeability. there was. Accordingly, the gas permeation characteristics of the manufactured hollow yarns were bad and there was a limit in increasing the uniformity of the product.

Thus, the inventors of the present invention, while conducting research to solve this problem, the polymer solution made by dissolving a gas-selective polymer in a high boiling point nonpolar organic solvent and a low boiling point polar solvent is well dissolved in a polar organic solvent without evaporation. By adding inorganic salts and thinning the outer surface selective layer of the hollow fiber membrane without defects, it was found that the gas selectivity maintains the properties of the polymer itself while the gas permeability is significantly increased than before, and the present invention has been completed.

An object of the present invention is to provide a mass production method of a hollow fiber membrane of asymmetric structure for highly selective permeable gas separation.

Another object of the present invention is to provide a hollow fiber membrane for carbon dioxide gas separation produced by the above production method.

Another object of the present invention to provide a hollow fiber membrane for oxygen gas separation produced by the above production method.

Another object of the present invention is to provide a hollow fiber membrane for hydrogen gas separation produced by the production method.

In order to achieve the above object, the present invention comprises the steps of preparing a mother liquor by mixing the gas-selective polymer, the first solvent, the second solvent and the inorganic additive and removing the bubbles (step 1);

Solidifying the inside of the hollow fiber membrane by spinning the mother liquor prepared in the step 1 and the internal coagulant together in the air layer (step 2);

Phase-transferring the outer surface of the hollow fiber membrane by immersing the hollow fiber membrane internally solidified in step 2 in a first coagulation tank (step 3);

Immersing the hollow fiber membrane whose phase is externally phase-transformed in step 3 in a second coagulation bath to remove the remaining solvent and winding it into a winding tank (step 4); And

It provides a mass production method of a hollow fiber membrane having a highly selective permeable gas separation asymmetric structure comprising the step of drying the hollow fiber membrane prepared in step 4 in an oven (step 5).

In addition, the present invention provides a hollow fiber membrane for separating carbon dioxide gas produced by the production method.

Furthermore, the present invention provides a hollow fiber membrane for oxygen gas separation produced by the above production method.

In addition, the present invention provides a hollow fiber membrane for hydrogen gas separation produced by the above production method.

Since the method of producing a hollow fiber membrane according to the present invention further increases the gas permeability and selectivity by adding an inorganic additive to the conventional hollow fiber membrane production method using a gas-selective polymer, a first solvent and a second solvent, It may be useful for the mass production of asymmetric structures of hollow fiber membranes for highly selective permeable gas separation.

1 is a device for manufacturing a hollow fiber membrane according to an embodiment of the present invention.
2 is a device for measuring the gas permeability of the hollow fiber membrane according to an embodiment of the present invention.
3 is an image of a hollow fiber membrane according to Example 1 of the present invention observed with a scanning electron microscope.
Figure 4 is an image of the hollow fiber membrane according to Example 2 of the present invention observed with a scanning electron microscope.
5 is an image of a hollow fiber membrane according to Example 3 of the present invention observed with a scanning electron microscope.
6 is an image of a hollow fiber membrane according to Example 4 of the present invention observed with a scanning electron microscope.
7 is an image of a hollow fiber membrane according to Example 5 of the present invention, observed with a scanning electron microscope.
8 is an image of a hollow fiber membrane according to Comparative Example 1 of the present invention observed with a scanning electron microscope.
9 is an image of a hollow fiber membrane according to Comparative Example 2 of the present invention observed with a scanning electron microscope.
10 is an image of a hollow fiber membrane according to Comparative Example 3 of the present invention observed with a scanning electron microscope.
11 is an image of a hollow fiber membrane according to Comparative Example 4 of the present invention observed with a scanning electron microscope.

Hereinafter, the present invention will be described in detail.

The present invention comprises the steps of preparing a mother liquor by mixing a gas-selective polymer, a first solvent, a second solvent and an inorganic additive and removing bubbles (step 1);

Solidifying the inside of the hollow fiber membrane by spinning the mother liquor and the internal coagulant prepared in step 1 together in the air layer (step 2);

Phase-transferring the outer surface of the hollow fiber membrane by immersing the hollow fiber membrane internally solidified in step 2 in a first coagulation tank (step 3);

Immersing the hollow fiber membrane whose phase is externally phase-transformed in step 3 in a second coagulation bath to remove the remaining solvent and winding it into a winding tank (step 4); And

It provides a mass production method of a hollow fiber membrane having a highly selective permeable gas separation asymmetric structure comprising the step of drying the hollow fiber membrane prepared in step 4 in an oven (step 5).

Hereinafter, the present invention will be described in detail step by step.

In the mass production method of the hollow fiber membrane according to the present invention, step 1 is a step of preparing a mother liquid. Specifically, a gas-selective polymer, a first solvent, a second solvent, and an inorganic additive are mixed, and bubbles are removed under reduced pressure to prepare a mother liquid.

The gas-selective polymer of the present step 1 may be used alone or in combination of polyisulfone, polysulfone, polyimide, polyimide, polyamide, polybenzimidazole, brominated polyisulfone, and the like.

At this time, it is preferable to prepare a mother liquid by adding 20 to 45% by weight of the gas-selective polymer, and more preferably to add 25 to 35% by weight.

If the gas-selective polymer is added in less than 20% by weight, the mechanical strength of the hollow fiber membrane is weak, and when it is added in excess of 45% by weight, the gas permeability is low.

The first solvent of the step 1 serves to dissolve the gas-selective polymer, a high boiling point nonpolar organic solvent such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide can be used.

At this time, it is preferable to prepare a mother liquid by adding 40 to 70% by weight of the first solvent.

If the first solvent is added in less than 40% by weight, the viscosity of the mother liquor is so high that the hollow fiber membrane skin layer is formed too densely, resulting in poor gas permeability, and when added in excess of 70% by weight. The viscosity of the mother liquor is low, so that the strength of the membrane is lowered, pores are formed, and there is a problem in the formation of the skin layer.

The second solvent of the present step 1 does not dissolve the gas-selective polymer but has a swelling property, thereby forming a skin-selective skin layer. As the second solvent, low boiling point nonsolvents such as water, methanol, ethanol, isopropyl alcohol, acetone, tetrahydrofuran and butoxyethanol can be used.

At this time, it is preferable to prepare a mother liquid by adding 10 to 30% by weight of the second solvent.

If the second solvent is added in less than 10% by weight, there is a problem that the amount is too small to form a skin layer with gas selectivity, and when added in excess of 30% by weight, the skin layer is too thick. Densely formed, there is also a problem that can be precipitated off the solubility of the polymer in the solution.

The inorganic additive of the first step serves to help the pore formation of the hollow fiber membrane, thereby significantly improving the gas permeability while minimizing defects such as pinholes on the outer surface of the hollow fiber membrane.

As the inorganic additive, lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, lithium chloride, sodium chloride, magnesium chloride, potassium chloride, etc. may be used.

At this time, it is preferable to prepare the mother liquid by adding 1 to 10% by weight of the inorganic additive.

If the inorganic additive is added in less than 1% by weight, there is a problem that it is difficult to expect the effect because the amount is too small, when added in excess of 10% by weight, the viscosity is too high, the solubility is not enough to uniform There is a problem that is difficult to prepare a solution.

In the mass production method of the hollow fiber membrane according to the present invention, the step 2 is to solidify the inside of the hollow fiber membrane by spinning the mother liquor and the internal coagulant prepared in step 1 to the air layer.

Specifically, in the hollow fiber membrane manufacturing apparatus of FIG. 1, the mother liquor with a constant flow rate is supplied to the outside of the double-tubular nozzle of the spinneret through a gear pump, and the internal coagulant with a constant flow rate is discharged through the liquid transfer pump (HPLC pump). It is fed into the double-tubular nozzle of the. The hollow fiber membrane radiated from the double-tubular nozzle of the spinneret passes through an air gap of a predetermined period and starts phase transition between the mother liquor and the internal coagulant to form an inner channel of the hollow fiber membrane.

In this case, the spinning method is generally used in the art, and is not particularly limited, and in the present invention, the hollow fiber membrane is manufactured using dry / wet spinning. At this time, the spinning temperature is 40 ~ 200 ℃, the spinning speed is 10 ~ 80 m / min, immersed in the primary coagulation bath through an air-gap (3 ~ 30 cm) from the spinneret to the outside of the hollow fiber membrane Phase change the surface.

If the spinning temperature is less than 40 ℃, there is a problem that high-speed spinning is impossible, if it exceeds 200 ℃, the evaporation of the first solvent and the viscosity of the mother liquor is rapidly reduced, so that the hollow fiber membrane is not smoothly spinning there is a problem. In addition, when the spinning speed is less than 10 m / min there is a problem that the productivity is lowered as in the conventional process, when the spinning speed exceeds 80 m / min there is a problem that the separation characteristics of the membrane does not appear due to the stretching effect of the hollow fiber membrane.

The internal coagulant of step 2 may be used by mixing the first solvent and the second solvent of step 1.

At this time, the mixing ratio of the internal coagulant is preferably used by mixing the first solvent: the second solvent in a weight ratio of 90:10 to 50:50.

Here, the first solvent serves to make the inside of the hollow fiber membrane a porous surface, which is the same as the first solvent used when preparing the mother liquid. In addition, the second solvent serves to prevent deformation of the hollow fiber membrane by hardening the phase structure of the internal structure in a short time for high speed spinning.

If the amount of the first solvent exceeds 90% by weight, the internal channel of the hollow fiber membrane is not completely fixed in the manufacturing process of the hollow fiber membrane, so that the eccentricity of the internal channel is increased, and the structure is greatly changed. If the amount of the solvent exceeds 50% by weight, the inside of the hollow fiber membrane may not be manufactured as a porous surface, and thus gas permeability is very low.

In the mass production method of the hollow fiber membrane according to the present invention, the step 3 is a step of immersing the hollow fiber membrane emitted in step 2 in the primary coagulation bath to harden the phase of the outer surface of the hollow fiber membrane in a short time. At this time, water may be used for the primary coagulation bath.

In the method for mass production of hollow fiber membranes according to the present invention, step 4 is a step of immersing in a secondary coagulation bath to remove the remaining solvent and wound in a winding tank. Specifically, the hollow fiber membrane of which the phase transition of the outer surface is finished in the primary coagulation tank is introduced into the secondary coagulation tank containing 30 ~ 60 ° C. of hot water at a constant speed through a tension controller to remove the remaining solvent and to the final winding tank. It is cold.

In the mass production method of the hollow fiber membrane according to the present invention, step 5 is a step of completing the production of the hollow fiber membrane by drying the hollow fiber membrane prepared in step 4 in an oven. Specifically, the drying step may be performed for 24 to 72 hours in an oven at 20 ~ 60 ℃.

The hollow fiber membrane produced by the mass production method according to the present invention is prepared by adding a second solvent for forming a skin layer having a high gas selectivity and an inorganic additive capable of significantly increasing gas permeability, thereby preparing a hollow fiber membrane, A hollow fiber membrane having an asymmetric structure having a thin selective separation layer having high gas permeability and high selectivity is produced.

The hollow fiber membrane prepared according to the present invention can be used very effectively to separate various gases such as methane, carbon dioxide, oxygen, hydrogen sulfide, nitrogen, hydrogen, water vapor and the like.

In particular, among the hollow fiber membranes according to one embodiment of the present invention, the hollow fiber membrane prepared in Example 1 was found to have excellent selectivity and permeability for carbon dioxide (see Table 1), and the hollow fiber membrane prepared in Example 3 The selectivity and permeability to oxygen were found to be very good (see Table 2), and the hollow fiber membrane prepared in Example 2 was found to have excellent selectivity and permeability to hydrogen (see Table 4).

Therefore, the hollow fiber membrane prepared by the mass production method of the present invention can be particularly useful as a hollow fiber membrane for separating carbon dioxide, oxygen and hydrogen in the gas phase.

Hereinafter, an Example demonstrates this invention in detail. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

< Example  1> Preparation of hollow fiber membranes including inorganic additives 1

In a 2000 ml round flask, 350 g of polyisulfone as a gas-selective polymer, 450 g of N-methylpyrrolidone (hereinafter referred to as NMP) as the first solvent, 100 g of acetone as the second solvent, lithium hydroxide as an inorganic additive 100 g was added and completely dissolved, and the resultant was decompressed using a vacuum pump to completely remove bubbles generated in the solution to prepare a mother liquid. A solution obtained by mixing NMP and water in a 90:10 weight ratio was prepared as an internal coagulant. The mother liquor and the internal coagulant were prepared using the apparatus shown in FIG. 1.

Specifically, the hollow fiber membrane manufacturing apparatus of FIG. 1 supplies the mother liquor of a certain flow rate through the gear pump to the outside of the double-tubular nozzle of the spinneret, and supplies the internal coagulant of the predetermined flow rate through the liquid transfer pump (HPLC pump). It is fed into the double-tubular nozzle of the. The hollow fiber membrane radiated from the double-tubular nozzle of the spinneret passes through an air gap of a certain period and starts phase transition between the mother liquor and the internal coagulant to start forming internal channels of the hollow fiber membrane. Water) and the outer surface of the used desert becomes phase change. The hollow fiber membrane of which phase transition is finished in the primary coagulation tank is introduced into the secondary coagulation tank at a constant speed through a tension controller to remove residual solvent and to be wound in the last winding tank. The hollow fiber membrane prepared through the above process was dried in an oven at 50 ° C. for at least 48 hours to complete the production of the hollow fiber membrane.

At this time, the length of the air layer was 15 cm, the spinning temperature was 50 ℃, the spinning speed was 50 m / min.

The outer diameter, cross section and structure of the inner and outer surfaces of the hollow fiber membrane prepared in Example 1 were analyzed using a scanning electron microscope (JEOL-840A) .The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200. Was 250 microns. The photographing result is shown in FIG.

< Example  2> Preparation of Hollow Fiber Membranes Containing Inorganic Additives 2

350 g of polyisulfone as a gas-selective polymer, 550 g of DMAc as a first solvent, 50 g of THF as a second solvent, and 50 g of sodium chloride as an inorganic additive were completely dissolved and decomposed using a vacuum pump to remove bubbles. The hollow fiber membrane was prepared by completely removing the mother liquor, using a solution containing DMAc and glycerin at a 70:30 weight ratio, using an internal coagulant, and using the above-described mother liquor and internal coagulant using the apparatus shown in FIG. When preparing the, the hollow fiber membrane was prepared in the same manner as in Example 1 except that the length of the air layer 5 cm, the spinning temperature is set to 70 ℃, the spinning speed is set to 75 m / min.

The outer diameter, cross section and structure of the inner and outer surfaces of the hollow fiber membrane prepared in Example 2 were analyzed using a scanning electron microscope (JEOL-840A) .The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200. Was 250 microns. The photographing result is shown in FIG.

< Example  3> Preparation of Hollow Fiber Membranes Containing Inorganic Additives 3

Add 300 g of polyimide as gas-selective polymer, 400 g of DMAc as the first solvent, 200 g of ethanol as the second solvent, and 100 g of lithium chloride as the inorganic additive, dissolve completely, and decompress the bubbles in the solution by using a vacuum pump. The hollow fiber membrane was prepared using the mother liquor prepared by removing the mother liquor, and a solution obtained by mixing DMAc and water in a 70:30 weight ratio using an internal coagulant. When preparing, the hollow fiber membrane was prepared in the same manner as in Example 1 except that the air layer had a length of 10 cm, a spinning temperature of 150 ° C., and a spinning speed of 15 m / min.

The outer diameter and cross section of the hollow fiber membrane prepared in Example 3 and the structure of the inner and outer surfaces thereof were analyzed using a scanning electron microscope (JEOL-840A) .The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200 Was 250 microns. The photographing result is shown in FIG.

< Example  4> Preparation of Hollow Fiber Membranes Containing Inorganic Additives 4

350 g of brominated polyisulfone as a gas-selective polymer, NMP 325 g as the first solvent, 200 g of acetone as the second solvent, 125 g of sodium chloride as the inorganic additive, completely dissolved, and decomposed in a solution by decompression using a vacuum pump. Using the mother liquor prepared by completely removing the solution, and using a solution containing NMP and acetone in a weight ratio of 70:30 as an internal coagulant, and using the apparatus shown in FIG. When preparing a desert, the hollow fiber membrane was prepared in the same manner as in Example 1 except that the air layer had a length of 5 cm, a spinning temperature of 180 ° C., and a spinning speed of 35 m / min.

The outer diameter, cross section and structure of the inner and outer surfaces of the hollow fiber membrane prepared in Example 4 were analyzed using a scanning electron microscope (JEOL-840A) .The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200. Was 250 microns. The photographing result is shown in FIG.

< Example  5> Preparation of Hollow Fiber Membranes Containing Inorganic Additives 5

175 g of polyimide and 175 g of polyisulfone as gas-selective polymer, 550 g of DMAc as the first solvent, 50 g of THF as the second solvent and 50 g of sodium chloride as the inorganic additive were completely dissolved and decompressed using a vacuum pump. The mother liquor prepared by completely removing the bubbles generated in the solution, using a solution containing DMAc and glycerin in a 70:30 weight ratio, prepared as an internal coagulant, and the mother liquor and internal coagulant prepared above are shown in FIG. When manufacturing the hollow fiber membrane by using, the hollow fiber membrane was carried out in the same manner as in Example 1 except that the air layer length was set to 5 cm, the spinning temperature is 70 ℃, the spinning speed is set to 75 m / min Prepared.

The outer diameter, cross section and structure of the inner and outer surfaces of the hollow fiber membrane prepared in Example 5 were analyzed using a scanning electron microscope (JEOL-840A). The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200. Was 250 microns. The photographing result is shown in FIG.

< Comparative example  1> Preparation of Hollow Fiber Membrane Using the Conventional Method 1

The mother liquor prepared by using 350 g of polyisulfone as a gas-selective polymer, 450 g of NMP as the first solvent, and 200 g of acetone as the second solvent was completely dissolved, and then completely removed bubbles generated in the solution by decompression using a vacuum pump. In the preparation of the hollow fiber membrane using the apparatus shown in FIG. 1 using the solution prepared by mixing NMP and water in a 90:10 weight ratio as the internal coagulant, and using the above-described mother liquor and the internal coagulant, A hollow fiber membrane was prepared in the same manner as in Example 1, except that 15 cm, spinning temperature was set to 50 ° C., and spinning speed was set to 50 m / min.

The outer diameter, cross section, and inner surface of the hollow fiber membrane prepared in Comparative Example 1 were analyzed using a scanning electron microscope (JEOL-840A) .The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200. Was 250 microns. The photographing result is shown in FIG.

< Comparative example  2> Preparation of Hollow Fiber Membrane Using the Conventional Method 2

A mother liquor prepared by using 350 g of polyisulfone as a gas-selective polymer, 550 g of DMAc as a first solvent, and 100 g of THF as a second solvent, completely dissolved, and then completely removing bubbles generated in the solution by decompression using a vacuum pump. In the preparation of the hollow fiber membrane using the apparatus shown in FIG. 1 using the solution prepared by mixing DMAc and glycerin in a 70:30 weight ratio as the internal coagulant, and using the above-described mother liquor and the internal coagulant, A hollow fiber membrane was prepared in the same manner as in Example 1, except that 5 cm, the spinning temperature was set to 70 ° C., and the spinning speed was set to 75 m / min.

The outer diameter, cross section, and inner surface of the hollow fiber membrane prepared in Comparative Example 2 were analyzed using a scanning electron microscope (JEOL-840A) .The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200. Was 250 microns. The photographing result is shown in FIG.

< Comparative example  3> Preparation of Hollow Fiber Membrane Using the Conventional Method 3

300 g of polyimide as the gas-selective polymer, 400 g of DMAc as the first solvent and 300 g of ethanol as the second solvent were completely dissolved, and the mother liquor prepared by completely removing bubbles generated in the solution by depressurization using a vacuum pump, When the hollow fiber membrane was prepared using a solution obtained by mixing DMAc and water in a weight ratio of 70:30 by using an internal coagulant, and the mother liquor and the internal coagulant prepared above using the apparatus shown in FIG. 1, the length of the air layer was 10. The hollow fiber membrane was manufactured by the same method as Example 1, except that cm, the spinning temperature was set at 120 ° C., and the spinning speed was set at 15 m / min.

The outer diameter, cross section and structure of the inner and outer surfaces of the hollow fiber membrane prepared in Comparative Example 3 were analyzed using a scanning electron microscope (JEOL-840A) .The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200. Was 250 microns. The photographing result is shown in FIG.

< Comparative example  4> Preparation of Hollow Fiber Membrane Using the Conventional Method 4

350 g of brominated polyisulfone as a gas-selective polymer, 325 g of NMP as the first solvent, and 325 g of acetone as the second solvent were completely dissolved, and the mother solution prepared by completely removing bubbles generated in the solution by depressurization using a vacuum pump was used. And a solution of NMP and acetone in a 70:30 weight ratio prepared using an internal coagulant, and the length of the air layer when the hollow fiber membrane was prepared using the above-described mother liquor and internal coagulant using the apparatus shown in FIG. The hollow fiber membrane was prepared in the same manner as in Example 1 except that 5 cm, the spinning temperature is 180 ℃, the spinning speed was set to 35 m / min.

The outer diameter, cross section, and structure of the inner and outer surfaces of the hollow fiber membrane prepared in Comparative Example 4 were analyzed using a scanning electron microscope (JEOL-840A) .The outer diameter of the manufactured hollow fiber membrane was about 400 microns and the inner diameter was about 200. Was 250 microns. The photographing result is shown in FIG.

< Experimental Example  1> Measurement of gas permeability of hollow fiber membrane with or without inorganic additive

In order to find out by comparing the gas permeability of each of the hollow fiber membranes prepared in Examples 1 to 5 and Comparative Examples 1 to 4 using the apparatus shown in FIG.

Specifically, the apparatus of Figure 2 is mounted in the permeation cell dozens of strands from the number of hollow fiber membranes prepared in Examples and Comparative Examples, the permeate gas is supplied to the inside or outside of the hollow fiber membrane at a certain pressure, in this case hollow fiber The flow rate of the gas permeated through the bubble was measured using a bubble flow meter (bubble flow meter).

First, permeation experiments were performed on nitrogen and carbon dioxide, wherein the pressure difference between the ^two ends of the membrane was 5 kg _f / cm ² , and the results are shown in Table 1 below.

The results of performing permeation experiments on nitrogen and oxygen are shown in Table 2 below.

The results of permeation experiments on methane and carbon dioxide are shown in Table 3 below.

The results of performing permeation experiments on hydrogen and carbon dioxide are shown in Table 4 below.

Yes radiation
speed
(m / min) radiation
Temperature
(℃) N ₂
Transmittance
(GPU) CO ₂
Transmittance
(GPU) CO ₂ / N ₂
Selectivity Example 2 15 25 11 240 21 Example 4 30 80 19 419 22 Example 5 30 80 17 352 21 Comparative Example 3 15 50 3 61 20 Comparative Example 4 9 25 4 56 14

Yes radiation
speed
(m / min) radiation
Temperature
(℃) N ₂
Transmittance
(GPU) O ₂
Transmittance
(GPU) O ₂ / N ₂
Selectivity Example 2 23 70 15 92 6.1 Example 3 14 40 20 116 5.8 Example 4 20 25 15 93 6.2 Example 5 20 25 16 93 5.8

Yes radiation
speed
(m / min) radiation
Temperature
(℃) CH ₄
Transmittance
(GPU) CO ₂
Transmittance
(GPU) CO ₂ / CH ₄
Selectivity Comparative Example 1 50 50 20 680 35 Comparative Example 2 50 50 18 618 34 Example 1 50 50 24 900 38 Example 2 5 25 18 650 36

Yes radiation
speed
(m / min) radiation
Temperature
( ^o C) H ₂
Transmittance
(GPU) CO ₂
Transmittance
(GPU) H ₂ / CO ₂
Selectivity Example 2 15 25 420 50 8 Example 4 30 80 240 40 6 Example 5 30 80 210 37 6 Comparative Example 3 15 50 183 31 6 Comparative Example 4 9 25 168 21 8

As shown in Tables 1 to 4, when preparing the mother liquor by adding the inorganic additives in Examples 1 to 5, it is easier to remove bubbles than the mother liquor without adding the inorganic additives in Comparative Examples 1 to 4 and more uniform It was confirmed that not only can a mother liquor be stably prepared, but also has a gas selectivity similar to that of a conventional hollow fiber membrane, but shows a significantly improved permeability.

Therefore, the hollow fiber membrane produced by the production method of the present invention is significantly improved permeability of the gas, it can be usefully used in the production of the hollow fiber membrane for gas separation.

Claims (14)

Preparing a mother liquor by mixing a gas-selective polymer, a first solvent, a second solvent, and an inorganic additive and removing bubbles (step 1);
Solidifying the inside of the hollow fiber membrane by spinning the mother liquor prepared in the step 1 and the internal coagulant together in the air layer (step 2);
Phase-transferring the outer surface of the hollow fiber membrane by immersing the hollow fiber membrane internally solidified in step 2 in a first coagulation tank (step 3);
Immersing the hollow fiber membrane whose phase is externally phase-transformed in step 3 in a second coagulation bath to remove the remaining solvent and winding it into a winding tank (step 4); And
Including the step (step 5) drying the hollow fiber membrane prepared in step 4 in an oven,
The inorganic additive of step 1 is lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, lithium chloride, sodium chloride, magnesium chloride, characterized in that the one selected from the group consisting of potassium chloride Mass production of asymmetric hollow fiber membranes for highly selective permeable gas separation.
The method of claim 1, wherein the gas-selective polymer of step 1 is one selected from the group consisting of polyisulfone, polysulfone, polyimide, polyimideimide, polyamide, polybenzimidazole, and brominated polyisulfone Mass production method of the hollow fiber membrane, characterized in that the mixture.
The method of claim 1, wherein the mother liquor of step 1 is a mass production method of the hollow fiber membrane, characterized in that containing 20 to 45% by weight of the gas-selective polymer.
The method of claim 1, wherein the mother liquor of step 1 is a mass production method of the hollow fiber membrane, characterized in that containing 25 to 35% by weight of the gas-selective polymer.
The method for mass production of a hollow fiber membrane according to claim 1, wherein the first solvent of step 1 is one selected from the group consisting of N-methylpyrrolidone, dimethylacetamide and dimethylformamide.
The method of claim 1, wherein the mother liquor of step 1 comprises a mass of 40 to 70% by weight of the first solvent.
The mass production of the hollow fiber membranes according to claim 1, wherein the second solvent of step 1 is one selected from the group consisting of water, methanol, ethanol, isopropyl alcohol, acetone, tetrahydrofuran and butoxyethanol. Way.
The method of claim 1, wherein the mother liquor of step 1 comprises 10 to 30% by weight of the second solvent.
delete The method of claim 1, wherein the mother liquor of step 1 comprises 1 to 10% by weight of an inorganic additive.
According to claim 1, wherein the internal coagulant of step 2 is a mass production method of the hollow fiber membrane, characterized in that the mixture of the first solvent: the second solvent in a weight ratio of 90:10 to 50:50.
Carbon fiber gas separation hollow fiber membrane prepared by the production method of claim 1.
Hollow fiber membrane for oxygen gas separation produced by the production method of claim 1.
Hollow fiber membrane for hydrogen gas separation produced by the production method of claim 1.

Images