KR20180080425A - Composite porous membrane of acetylated alkyl cellulose and polyolefinketone - Google Patents

Abstract

The present invention relates to a composite porous membrane. The composite porous membrane comprises a support layer and a coating layer provided concentrically at an outer circumference of the support layer to encase the support layer, wherein the support layer contains an acetylated alkyl cellulose polymer, and the coating layer contains a polyolefin ketone polymer. The composite porous membrane has high water permeability and high removal rate while maintaining high strength, and thus can be applied to next-generation high-efficiency separation processes such as a separation membrane module for purified water treatment, a separation membrane module for reusable wastewater treatment, a submerged separation membrane module for a bio-membrane reactor, a module for separation of chemical mixtures, a pretreatment separation membrane for seawater desalination, and the like.

Description

Technical Field [0001] The present invention relates to a composite hollow fiber membrane comprising an acetylated alkyl cellulose and a polyolefin ketone,

The present invention relates to a composite hollow fiber membrane, and more particularly, to a hollow fiber membrane having a surface and cross-sectional porosity using an acetylated alkylcellulose polymer, coating the surface of the hollow fiber membrane with a polyolefin ketone polymer, The present invention relates to a composite hollow fiber membrane capable of being applied to a membrane distillation process, because it has excellent water vapor permeability and excellent salt removal efficiency by densely changing the surface.

Membrane distillation process is operated at low pressure compared with ultrafiltration and reverse osmosis process using porous membrane and separation by vapor pressure partial pressure difference. Further, when the above-mentioned membrane distillation separation method is used, it is not necessary to use a filter or separation membrane that operates at high pressure without entrainment of a conventional distillation method in separating and removing nonvolatile substances such as salts. Due to the advantages of this membrane distillation separation process, the desalination process using the membrane distillation process is emerging as one of the competitive methods in the production of drinking water all over the world.

Membrane distillation utilizes a hydrophobic polymer membrane. The membrane or membrane (hydrophilic material) has a surface tension greater than that of the membrane, so that it can not pass through the membrane pore in the liquid state and is repelled on the surface of the membrane. At the pore inlet, the substance to be separated is phase-converted into a vapor phase, diffused and permeated into pores, and finally condensed and separated at the permeation side. This membrane distillation method is carried out through a separation membrane module comprising a feed side through which the feed solution passes through the separation membrane and a permeate side through which the separation material condenses and separates. At this time, studies on the permeation rate of water in accordance with the supply temperature, the supply flow rate, and the membrane material are progressing.

Korean Patent No. 10-1453803 discloses a method for producing a polyethylene terephthalate film, which comprises melt-extruding PTFE hollow fiber as a support layer together with ultra-high molecular weight polyethylene having a melting point lower than that of the support layer, Wherein the ultrahigh molecular weight polyethylene has a weight average molecular weight of 5,000,000 to 7,000,000, and the melt extrusion temperature during the melt extrusion is 130 ° C to 150 ° C. Discloses a method for producing a separator.

However, in the case of the conventional membrane distillation membrane, a hydrophobic membrane material is used to solve the problem of lowering the removal rate due to the wetting of the membrane pore, but pore wetting occurs due to condensation of steam at the front or rear of the pore during long- Therefore, there arises a problem that not only the substance to be removed such as sodium chloride permeates the separation membrane but also the diffusion rate of the supply solution stays in the pores serving as the diffusion path of the water vapor.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the problems of the prior art described above, and an object of the present invention is to solve the problem of pore wetting of a hollow fiber membrane applied to a conventional membrane distillation method, To provide a composite hollow fiber membrane applicable to a membrane distillation method.

According to an aspect of the present invention,

A support layer, and a coating layer concentrically formed on an outer circumferential surface of the support layer and surrounding the support layer, wherein the support layer comprises an acetylated alkyl cellulose polymer, and the coating layer comprises a polyolefin ketone polymer. It is about the desert.

The polyolefin ketone resin of the formula (1) has an intrinsic viscosity of 4 to 7, and the polyolefin ketone resin of the formula (2) has an intrinsic viscosity of 1 to 3 , And the content of propylene is 3 to 10 mol%.

[Chemical Formula 1]

Wherein n is a real number from 4,000 to 13,000,

(2)

Wherein n is a real number from 500 to 2,000 and m is a real number from 15 to 200. [

The composite hollow fiber membrane of the present invention may further include an intermediate support layer including a cellulose-based polymer between the base layer and the coating layer. The support layer may have an average pore of 0.08 탆 to 0.2 탆, and the intermediate support layer may have an average pore of 0.05 탆 to 0.1 탆.

According to another aspect of the present invention,

Forming a support layer by forming a support layer doping solution containing an acetylated alkylcellulose polymer and a poor solvent; And

A coating layer doped with a polyolefin ketone polymer and a coating layer formed on the acetylated alkyl cellulose support layer to form a coating layer.

The acetylated alkylcellulose support layer may be produced by a heat-induced phase separation method, and the polyolefin ketone coating layer may be formed by a non-solvent-derived phase separation method.

The method of the present invention may further comprise the step of forming an intermediate support layer composed of a cellulose-based polymer between the acetylated alkylcellulose support layer-forming step and the polyolefin ketone coating layer-forming step. The intermediate support layer may be formed by a non-solvent-derived phase separation method.

Since the composite hollow fiber membrane of an acetylated alkyl cellulose and a polyolefin ketone according to the present invention has a dense surface layer and a very small pore structure on the surface thereof, water can not be directly passed through. However, the polyolefin ketone material, , The acetylated alkyl cellulose constituting the support layer has a high hydrophilicity and a porous structure, so that water molecules permeating the surface layer can easily migrate and maintain high permeability.

The composite hollow fiber membrane according to the present invention maintains a high water permeability and high salt removal rate while maintaining a high strength, and can be used as a membrane module for water treatment, a membrane module for heavy water treatment, an immersion membrane module for biofilm reactor, a module for chemical mixture separation, It is possible to apply it to the next generation high efficiency separation process such as the pretreatment separation membrane module.

1 is a schematic diagram of a membrane distillation apparatus used in an embodiment.
FIG. 2 is a photograph of a section of the composite hollow fiber membrane produced by Example 1 of the present invention by a scanning electron microscope. FIG.
FIG. 3 is a photograph of a cross section of the composite hollow fiber membrane produced in Example 2 of the present invention by scanning electron microscopy. FIG.
4 is a photograph of a cross section of the composite hollow fiber membrane produced in Comparative Example 1 by scanning electron microscope.
5 is a photograph of a cross section of the composite hollow fiber membrane produced in Comparative Example 2 by scanning electron microscopy.

Hereinafter, the present invention will be described in more detail. In describing the present invention, a detailed description of well-known functions or constructions may be omitted for clarity of the present invention.

According to one aspect of the present invention, there is provided a semiconductor device comprising a support layer, and a coating layer concentrically formed on an outer circumferential surface of the support layer and surrounding the support layer, wherein the support layer comprises an acetylated alkyl cellulose polymer and the coating layer comprises a polyolefin ketone polymer The present invention relates to a composite hollow fiber membrane,

Since the acetylated alkylcellulose polymer has high water-permeability and porous structure, it has excellent water permeability and excellent stain resistance. As the support layer includes the acetylated alkylcellulose polymer, water permeability and stain resistance of the support layer are improved . On the other hand, since the polyolefin ketone layer has a dense and small pore structure, it solves the problem of pore-wetting of the hollow fiber membrane applied to membrane distillation method by selectively passing only vaporized water molecules, thereby providing a membrane with high water permeability and high salt removal rate can do.

The alkyl group of the acetylated alkyl cellulose may be a methyl group, an ethyl group, a propyl group, a hydroxy group, a hydroxypropyl group or the like, and the support layer may include at least one of the above-mentioned acetylated alkylcellulose polymers.

The polyolefin ketone resin of the formula (1) has an intrinsic viscosity of 4 to 7, and the polyolefin ketone resin of the formula (2) has an intrinsic viscosity of 1 to 3 , And the content of propylene is 3 to 10 mol%.

Wherein n is a real number from 4,000 to 13,000,

Wherein n is a real number from 500 to 2,000 and m is a real number from 15 to 200. [

In the composite hollow fiber membrane of the present invention, the support layer is prepared by a heat-induced phase separation method, and the coating layer can be produced by a non-solvent-derived phase separation method.

In another embodiment of the present invention, the composite hollow fiber membrane of the present invention may further include a middle support layer including a cellulose-based polymer between the base layer and the coating layer. The intermediate support layer may be prepared by a non-solvent-derived phase separation method. Since the support layer is formed by the heat-induced phase separation method, the pore size of the surface is larger than that of the intermediate support layer formed by the non-solvent induction phase separation method and the smoothness is low. Thus, when the polyolefin ketone coating layer is coated on the intermediate support layer, It is possible.

In the composite hollow fiber membrane composed of the support layer, the intermediate support layer, and the coating layer, the support layer may have an average pore size of 0.1 탆 to 5 탆, and the intermediate support layer may have an average pore size of 0.03 탆 to 0.1 탆.

The cellulose-based polymer constituting the intermediate support layer may be at least one selected from the group consisting of acetylated alkylcellulose, cellulose acetate, cellulose triacetate, cellulose prophylanate, cellulose butyrate, cellulose acetylpropionate, cellulose diacetate, cellulose dibutyrate and cellulose tributyrate And the like.

Another aspect of the present invention relates to a method for producing a composite hollow fiber membrane.

In the method of the present invention, a support layer is formed by forming a support layer doping solution containing an acetylated alkylcellulose polymer and a poor solvent, and then a coating layer doping solution containing a polyolefin ketone polymer is prepared and coated on the acetylated alkyl cellulose support layer To form a polyolefin ketone coating layer.

Wherein the polyolefin ketone resin of Formula 1 has an intrinsic viscosity of 4 to 7 and the polyolefin ketone resin of Formula 2 has an intrinsic viscosity of 1 to 3, A content of 3 to 10 mol% can be used.

[Chemical Formula 1]

Wherein n is a real number from 4,000 to 13,000,

(2)

Wherein n is a real number from 500 to 2,000 and m is a real number from 15 to 200. [

In the present invention, the acetylated alkyl cellulose backing layer is formed by a heat-induced phase separation method, and the polyolefin ketone coating layer is formed by a non-solvent-derived phase separation method.

The process of preparing a hollow fiber membrane by a thermally induced phase separation method (TIPS) using an acetylated alkylcellulose polymer involves contacting a dope solution dissolved at a high temperature with a medium at a low temperature to cause liquid-solid phase separation and solidification to achieve a porous separator The process of preparing a coating by non-solvent-induced phase separation (NIPS) using a polyolefin ketone polymer comprises dissolving a polymer in a solvent capable of dissolving the polymer and interchanging the solvent and the non-solvent in the dope solution Liquid-solid phase separation and solidification are induced to form a porous separator.

By using TIPS for the support layer and phase separation using the NIPS coating layer, it is possible to form a hollow fiber membrane which is easy to control pores with high strength and high water permeability.

  In the method for producing a composite hollow fiber membrane according to an embodiment of the present invention, the dope solution forming the support layer includes an acetylated alkyl cellulose and a poor solvent. In this case, the content ratio of each component is preferably 15 to 40% by weight of the acetylated alkyl cellulose and 60 to 85% by weight of the poor solvent.

As the poor solvent in the production method of the present invention, hydrophilic polymers or organic substances easily soluble in water such as polyethylene glycol, polyvinyl alcohol, maleic anhydride and a surfactant may be added to the acetylated alkyl cellulose dope solution alone or as a mixture of two or more thereof And it is preferable to use polyethylene glycol.

The dope solution may be degassed by decompression or the like in order to remove bubbles remaining in the solution before the dope solution is radiated, and the deaerated dope solution may contain impurities present in the solution, in particular an undissolved polymer or a carbonized polymer However, the manufacturing method of the present invention is not limited thereto, and the degassing and filtering may be selectively performed by checking the state of the dope solution.

In the present invention, the dope solution for forming the support layer is preferably prepared at 130 to 200 ° C, and must be subjected to a defoaming process in order to remove bubbles present in the solution. Generally, the hollow fiber membrane is solidified at a temperature of 130 ° C or lower, or a hollow fiber membrane is formed by phase separation upon contact with a non-solvent at 130 ° C or lower. Thus, for the production of the acetylated alkyl cellulose backing layer, it is preferable to discharge the dope solution as a coagulating solution through a spinning nozzle maintaining a temperature of at least 130 캜, preferably 130 캜 to 180 캜.

The polyolefin ketone coating layer can be produced by, for example, a liquid coating method. In the liquid coating method, a polyolefin ketone is dissolved in an appropriate solvent to prepare a coating solution. The concentration of the copolymer in the coating liquid prepared at this time is not particularly limited, and may be, for example, 0.5% (w / v) to 8% (w / v). Examples of the solvent that can be used in the preparation of the coating solution include at least one metal salt aqueous solution selected from the group consisting of ZnCl2, CaCl2 and LiCl, m-cresol, hexafluoro-2- propanol, HFIP), but are not limited thereto.

Further, a pore-controlling agent may be additionally used to control the pore size of the polyolefin ketone coating layer to be produced. Such a pore-controlling agent may be selected from known pore-controlling agents so as to be suitable for the desired pore size and added in an appropriate amount. Poly (ethylene glycol), poly (vinylpyrrolidone), and poly (vinyl alcohol) may be selectively used as a pore regulator for increasing the pore size, and pore regulators for reducing the pore size include 1,4 -Dioxane, diethylene glycol dimethyl ether, etc. may be optionally used.

In the liquid coating method, the coating liquid prepared as described above is coated on a support, followed by phase separation in a coagulation bath, followed by washing and drying, thereby preparing a separation membrane. As the coating method, a usual method such as dip coating, spin coating or spray coating can be used.

When the polyolefin ketone is phase-separated, the non-solvent-derived phase separation method can be used. In this case, the solvent used as the non-solvent may be selected from the group consisting of? -Butyrolactone, ethanol, and lithium chloride.

In another embodiment, a step of forming an intermediate support layer composed of a cellulose-based polymer may be further included between the step of preparing the acetylated alkyl cellulose support layer and the step of forming the polyolefin ketone coating layer. At this time, the intermediate support layer may be formed by a non-solvent-derived phase separation method.

When the support layer is formed of two layers as described above, the support layer dope solution and the intermediate support layer constituting the intermediate support layer and the hollow formative agent can be simultaneously radiated into the external coagulation bath through the triple nozzle to form the support layer hollow fiber membrane . At this time, the dope solution for discharging the hollow forming agent is discharged as the inner nozzle of the triple spinneret, the dope solution for forming the intermediate supporting layer is discharged as the outer nozzle, and the dope solution for forming the supporting layer is discharged as the nozzle between the inside and the outside . As a result, the composite hollow fiber membrane can be manufactured which has a uniform thickness even after the hollow fiber membrane is formed and the coating layer is not peeled off, by simultaneously spinning the support layer and the intermediate support layer dope solution through the triple spinneret.

The method of forming the polyolefin ketone coating layer is as described above.

  In the present invention, a washing process may be further included to remove organic matter including solvent remaining in the membrane of the hollow fiber membrane transferred from the coagulating solution into the atmosphere. The use of water as a washing solution is preferred, and the washing time is not particularly limited, but is preferably at least 1 day and at most 5 days.

The drying conditions to be performed after the washing process are not particularly limited as long as the drying process is performed under conditions in which the solvent contained in the coating liquid can be sufficiently removed. For example, after the coating, the separation membrane is placed in an oven or vacuum oven, Lt; 0 > C for about 24 hours.

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited by the following examples.

Example

Example  One

A support layer hollow fiber membrane was prepared by dissolving 25 wt% of acetylated methyl cellulose (AMC) and 75 wt% of triethylene glycol at 160 캜, spinning through a spinneret, and solidifying in a coagulation bath composed of 25 캜 water . The prepared support layer hollow fiber membrane was coated with a coating solution composed of 10 wt% of polyolefin ketone and 90 wt% of meta cresol by a dipping method and then solidified in a coagulation bath composed of 25 DEG C ethanol to obtain a polyolefin ketone coating layer To prepare a hollow hollow fiber membrane of acetylated methylcellulose and a polyolefin ketone.

Example  2

25 wt% of acetylated methyl cellulose and 75 wt% of triethylene glycol were dissolved at 160 캜 to prepare a support layer doped solution, and 10 wt% of acetylated methyl cellulose and 90 wt% of dimethylacetamide were dissolved at 60 캜 to prepare an intermediate support layer dope solution . Subsequently, the supported layer doped solution containing the prepared acetylated methylcellulose polymer and the intermediate supported layer doped solution were discharged through a triple spinneret, and a heat-induced phase separation method solidifying in a coagulation bath composed of water at 25 ° C and a non-solvent derived phase separation method were combined A hollow fiber membrane was prepared. The hollow fiber membrane thus prepared was coated on a solution composed of 10 wt% of polyolefin ketone and 90 wt% of meta-cresol by a dipping method, and then solidified in a coagulation bath composed of 25 DEG C ethanol to form a polyolefin ketone coating layer To prepare a composite hollow fiber membrane of cellulose acetate and polyolefin ketone.

Comparative Example  One

25 wt% of acetylated methyl cellulose and 75 wt% of triethylene glycol were dissolved at 160 캜 and discharged through a spinneret, and a hollow fiber membrane was prepared by a heat induction phase separation method of solidifying in a coagulation bath composed of water at 25 캜.

Comparative Example  2

25 wt% of acetylated methyl cellulose and 75 wt% of triethylene glycol were dissolved at 160 캜 to prepare a base layer doped solution, and 90 wt% of acetylated methyl cellulose and 10 wt% of dimethylacetamide were dissolved at 60 캜 to prepare a coating layer dope solution . A support layer doped with a prepared acetylated methyl cellulose polymer and a coating layer doped with a hollow fiber membrane in combination with a heat induction phase separation method of solidifying in a coagulation bath composed of water at 25 ° C and a non-solvent- .

Test Example  1: Scanning electron microscope analysis

The composite hollow fiber membranes prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were observed using a scanning electron microscope. The results are shown in FIGS. 2 to 5.

As shown in FIG. 2-3, a cross section of the composite hollow fiber membranes prepared in Examples 1 and 2 was observed with a scanning electron microscope. As a result, it was found that a polyolefin ketone coating layer was well formed on the outer surface of the acetylated alkylcellulose support layer .

Test Example  2: Permeation performance analysis

The properties of the composite hollow fiber membranes prepared in Examples 1 to 2 and Comparative Examples 1 and 2 are shown in FIG. 1 for comparison of the permeation performance of the composite hollow fiber membranes or composite hollow fiber membranes prepared in Examples and Comparative Examples of the present invention The following permeation performance analysis experiments were conducted using the membrane distillation apparatus as shown in Table 1. The results of the analysis are shown in Table 1 below.

1) Test Example 1 - Permeation evaluation

The permeation flux of water vapor over an aqueous NaCl solution of 3.5% at 60 DEG C was measured through the composite hollow fiber membrane of the membrane distillation apparatus of Fig. Air was passed through the hollow fiber membrane at a flow rate of 1 l / min to the hollow portion of the hollow fiber membrane at a temperature of 60 ° C and 3.5% at the outside of the hollow fiber membrane, and the amount of water vapor And the permeate flow rate was calculated by evaluating the amount of water vapor permeated per unit time and unit area.

2) Test Example  2 - Salt removal rate  evaluation

The salt removal rate was calculated by the following equation.

Where R is the salt removal rate, Cf is the solute concentration in the aqueous NaCl solution, and Cp is the solute concentration in the permeate water obtained by condensing the permeated water vapor.

Hollow fiber membrane
Water vapor permeability
(g / ft2, d) Salt Removal Rate (%) Comparative Example 1 7.49 75.432 Comparative Example 2 12.36 30.227 Example 1 4.18 99.999 Example 2 6.39 99.999

The results of Table 1 indicate that the composite hollow fiber membrane of the present invention prepared in Examples 1 and 2 has a salt removal rate higher than that of the acetylated alkyl cellulose membranes prepared in Comparative Examples 1 and 2 It can be confirmed that it is excellent.

The composite hollow fiber membrane according to the present invention is a coating layer comprising a support layer containing an acetyl alkyl cellulose polymer having excellent water permeability and excellent stain resistance, dense pores and a high salt removal rate, and a polyolefin ketone polymer having high mechanical strength and chemical resistance To maintain high water permeability, to exhibit excellent salt removal rate and mechanical properties. In addition, the hollow fiber membrane according to the present invention can be applied to water treatment processes such as seawater, brine, sewage, and wastewater, and is particularly applicable to a desalination process.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, will be. Accordingly, the scope of protection of the present invention should be determined not only in the claims of the following claims, but also in the scope of equivalents to the claims.

Claims (17)

A support layer, and a coating layer concentrically formed on an outer circumferential surface of the support layer and surrounding the support layer, wherein the support layer comprises an acetylated alkyl cellulose polymer, and the coating layer comprises a polyolefin ketone polymer. desert.
The polyolefin ketone resin of claim 1, wherein the polyolefin ketone resin has an intrinsic viscosity of 4 to 7, and the polyolefin ketone resin of formula (2) An intrinsic viscosity of 1 to 3, and a propylene content of 3 to 10 mol%.
[Chemical Formula 1]

Wherein n is a real number from 4,000 to 13,000,
(2)

Wherein n is a real number from 500 to 2,000 and m is a real number from 15 to 200. [
The composite hollow fiber membrane according to claim 1, wherein the support layer is produced by a heat-induced phase separation method, and the coating layer is a membrane produced by a non-solvent-derived phase separation method.
The composite hollow fiber membrane according to claim 1, wherein the composite hollow fiber membrane further comprises an intermediate support layer between the base layer and the coating layer, the intermediate support layer comprising a cellulosic polymer.
5. The composite hollow fiber membrane according to claim 4, wherein the supporting layer has an average pore of 0.08 to 0.2 m and the average supporting pore has an average pore of 0.05 to 0.1 m.
[5] The method of claim 4, wherein the cellulose-based polymer constituting the intermediate support layer is selected from the group consisting of acetylated alkylcellulose, cellulose acetate, cellulose triacetate, cellulose propriatalate, cellulose butyrate, cellulose acetylpropionate, cellulose diacetate, Cellulose triflate and cellulose tributyrate. ≪ RTI ID = 0.0 > 11. < / RTI >
The composite hollow fiber membrane according to claim 4, wherein the intermediate support layer is a membrane produced by a non-solvent-derived phase separation method.
Forming a support layer by forming a support layer doping solution containing an acetylated alkylcellulose polymer and a poor solvent; And
Preparing a coating layer doping solution containing a polyolefin ketone polymer, and coating the coating layer around the acetylated alkyl cellulose supporting layer to form a coating layer.
The polyolefin ketone resin of Claim 1, wherein the polyolefin ketone resin has an intrinsic viscosity of 4 to 7, and the polyolefin ketone resin of Formula (2) An intrinsic viscosity of 1 to 3, and a propylene content of 3 to 10 mol%.
[Chemical Formula 1]

Wherein n is a real number from 4,000 to 13,000,
(2)

Wherein n is a real number from 500 to 2,000 and m is a real number from 15 to 200. [
The process for producing a composite hollow fiber membrane according to claim 8, wherein the acetylated alkyl cellulose support layer is formed by a heat induction phase separation method and the polyolefin ketone coating layer is formed by a non-solvent- Way.
The method of claim 8, further comprising forming an intermediate support layer composed of a cellulose-based polymer between the step of preparing the acetylated alkylcellulose support layer and the step of forming the polyolefin ketone coating layer. 12. The method of claim 11, wherein the intermediate support layer is formed by a non-solvent-derived phase separation method.
12. The method of claim 11, wherein the method further comprises simultaneously radiating the intermediate support layer dope solution and the hollowing agent constituting the support layer dope solution and the intermediate support layer to an external coagulation bath through a triple nozzle. Method of manufacturing desert.
The process for producing a composite hollow fiber membrane according to claim 8, wherein the poor solvent is at least one selected from the group consisting of polyethylene glycol, polyvinyl alcohol, and maleic anhydride.
The method according to claim 10, wherein the solvent used as a non-solvent in the non-solvent-derived phase separation method is selected from the group consisting of? -Butyrolactone, ethanol, and lithium chloride. Way.
12. The method for producing a composite hollow fiber membrane according to claim 11, wherein the solvent used for the NMP-induced phase separation of the intermediate support layer is N, N-dimethylacetamide or 1-methyl- .
The method according to claim 8, wherein the temperature of the polymer dope solution forming the support layer is in the range of 130 to 180 캜.

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