KR101982909B1 - Hollow fiber membrane and method for preparing the same - Google Patents

Abstract

The hollow fiber membrane of the present invention has a multi-layer structure including a polymer support layer forming an inner circumferential surface and a polymer coating layer surrounding the support layer to form an outer circumferential surface.

Description

HOLLOW FIBER MEMBRANE AND METHOD FOR PREPARING THE SAME [0002]

The present invention relates to a hollow fiber membrane and a method for producing the hollow fiber membrane.

With the development of the industry and population growth, interest in efficient water use and treatment technologies is increasing. In recent years, membrane technology has been increasingly applied to ensure water quality stability in water treatment, under-wastewater treatment, and seawater desalination. Particularly, the hollow fiber membrane has a high area per unit volume, few membrane fouling, and is easy to wash.

Generally, polysulfone, PE, PP, CA (cellulose acetate) and PVDF (polyvinylidene fluoride) are used as water treatment membrane materials. PVDF (Polyvinylidene fluoride) membranes, which are superior in strength and chemical resistance, have recently been used for water purification and industrial use because they are physically and chemically treated to control membrane contamination in a water treatment process in which a membrane is used. And is widely used as a separator.

However, the PVDF (polyvinylidene fluoride) membrane has a disadvantage in that the mechanical strength is weak if the pores are fine according to the production method, and if the mechanical strength is high, the pores become large and the hollow fiber membrane having the UF grade or higher can not be obtained.

On the other hand, there is an effort to improve the water permeability by controlling the pore size of the separator, but if the pore size is increased, the strength, the pressure resistance and the chemical resistance of the separator are deteriorated.

Therefore, it is necessary to provide a separation membrane having an excellent mechanical strength, capable of filtration beyond the ultrafiltration membrane grade (UF grade) and improved water permeability.

With the development of the industry and population growth, interest in efficient water use and treatment technologies is increasing. In recent years, membrane technology has been increasingly applied to ensure water quality stability in water treatment, under-wastewater treatment, and seawater desalination. Particularly, the hollow fiber membrane has a high area per unit volume, few membrane fouling, and is easy to wash.

Generally, polysulfone, PE, PP, CA (cellulose acetate) and PVDF (polyvinylidene fluoride) are used as water treatment membrane materials. PVDF (Polyvinylidene fluoride) membranes, which are superior in strength and chemical resistance, have recently been used for water purification and industrial use because they are physically and chemically treated to control membrane contamination in a water treatment process in which a membrane is used. And is widely used as a separator.

However, the PVDF (polyvinylidene fluoride) membrane has a disadvantage in that the mechanical strength is weak if the pores are fine according to the production method, and if the mechanical strength is high, the pores become large and the hollow fiber membrane having the UF grade or higher can not be obtained.

On the other hand, there is an effort to improve the water permeability by controlling the pore size of the separator, but if the pore size is increased, the strength, the pressure resistance and the chemical resistance of the separator are deteriorated.

Therefore, it is necessary to provide a separation membrane having an excellent mechanical strength, capable of filtration beyond the ultrafiltration membrane grade (UF grade) and improved water permeability.

One aspect of the present invention relates to a hollow fiber membrane.

According to one embodiment, the hollow fiber membrane has a multi-layer structure including a polymer support layer forming an inner circumferential surface and a polymer coating layer surrounding the support layer to form an outer circumferential surface.

The average pore size of the polymer support layer may be more than 0.05 탆 and 0.3 탆, and the average pore size of the polymer coating layer may be 0.01 탆 to 0.05 탆.

The thickness of the polymer support layer may be 70% to 98% of the total thickness.

The hollow fiber membrane may have a water permeability of 1,000 LMH / bar or more and a tensile strength of 0.7 kgf / fiber or more.

Another aspect of the present invention relates to a hollow fiber membrane manufacturing method.

In one embodiment, the hollow fiber membrane manufacturing method is characterized in that the vinylidene fluoride polymer resin is used in an amount of 10 wt% or more and less than 20 wt%, a good solvent 70-88.9 wt%, a hydrophilic additive 1 - 10 wt%, and acetylated methylcellulose 0.1 - And 5 to 20% by weight of a solvent, 25 to 73.9% by weight of a plasticizer, and 1 to 10% by weight of a hydrophilic additive, based on the total weight of the polymeric coating layer and the vinylidene fluoride polymer resin. And a step of radiating and solidifying the composition for a polymeric support layer through a triple spinneret.

The composition for the polymeric support layer may further contain 0.1 to 5% by weight of acetylated methylcellulose.

In the hollow fiber membrane producing method, the composition for polymer coating layer is radiated to the outer channel of the triple spinneret, the composition for polymer support layer is radiated to the middle channel of the triple spinneret, and the inner coherent solution is not discharged .

In another embodiment, the hollow fiber membrane manufacturing method may further include a step of stretching after the solidification.

The hollow fiber membrane according to another embodiment of the present invention can be produced by the hollow fiber membrane production method, and can have a water permeability of 1,000 LMH / bar or more and a tensile strength of 0.7 kgf / fiber or more.

The present invention has an effect of providing a hollow fiber membrane excellent in mechanical strength and water permeability, capable of UF grade and higher filtration, and a method for producing the hollow fiber membrane.

1 is a cross-sectional view of a hollow fiber membrane according to an embodiment of the present invention.
FIG. 2 is a schematic view of a triple spinneret used in a hollow fiber membrane manufacturing method according to one embodiment of the present invention.
FIG. 3 is an electron microscope image obtained by enlarging (400 times) the cross section of the support layer and coating layer of the hollow fiber membrane of Example 1 of the present invention.
4 is an electron microscope image obtained by enlarging (5,000 times) the cross section of the support layer of Example 1 of the present invention.

Hereinafter, the present invention will be described in more detail.

In the following description of the present invention, detailed description of known related arts will be omitted when it is determined that the gist of the present invention may be unnecessarily obscured by the present invention.

In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

Also, in interpreting the constituent elements, even if there is no separate description, it is interpreted as including the error range.

In the present specification, 'X to Y' representing the range means 'X or more and Y or less'.

Hollow fiber membrane

A hollow fiber membrane according to one embodiment of the present invention will be described with reference to FIG. 1 is a cross-sectional view of a hollow fiber membrane according to an embodiment of the present invention.

1, a hollow fiber membrane 100 according to an embodiment of the present invention includes a polymer support layer 10 forming an inner circumferential surface and a polymer coating layer 20 surrounding the support layer 10 to form an outer circumferential surface. Structure.

The hollow fiber membrane includes the polymer support layer 10 and the polymer coating layer 20 so that the hollow fiber membrane can be subjected to ultrafiltration (UF grade) filtration and further filtration of the hollow fiber membrane, and the mechanical strength and water permeability are excellent.

The polymer support layer 10 functions to increase the strength of the hollow fiber membrane by forming the inner circumferential surface of the hollow fiber membrane.

The average pore size of the polymer support layer 10 is more than 0.05 탆 and not more than 0.3 탆, specifically 0.08 탆 to 0.15 탆. In the pore size range, the polymer support layer can secure sufficient strength. The thickness of the polymer support layer may be 70% to 98%, specifically 75% to 95%, more specifically 80% to 90% of the total thickness. In the above-mentioned thickness range, the hollow fiber membrane is excellent in balance of strength and water permeability.

The polymer coating layer 20 may form an outer circumferential surface of the hollow fiber membrane to increase water permeability and water treatment efficiency of the hollow fiber membrane. The crystal structure of the polymer coating layer 20 may be a sponge-like crystal structure, and specifically includes a pore formed by partitioning the resin solid constituting the mesh.

For example, the average pore size of the polymer coating layer 20 is 0.001 μm to 0.05 μm, specifically 0.01 μm to 0.05 μm. In an embodiment, the average pore size of the polymeric support layer 10 may be greater than the average pore size of the polymeric coating layer 20. In the pore size range, the polymer coating layer is capable of ultrafiltration (UF grade) and further filtration and has excellent water treatment efficiency.

The hollow fiber membrane 100 preferably has a water permeability of 1,000 LMH / bar or more, for example, 1,000 LMH / bar to 4,000 LMH / bar, specifically 1,100 LMH / bar to 3,000 LMH / bar and a tensile strength of 0.7 kgf / For example 0.7 kgf / fiber to 3.0 kgf / fiber, specifically 1.0 kgf / fiber to 2.0 kgf / fiber.

Hollow fiber membrane manufacturing method

The method for producing a hollow fiber membrane according to one embodiment of the present invention may include a step of radiating and solidifying the composition for a polymer coating layer and the composition for a polymeric support layer through a triple spinneret.

The composition for the polymer coating layer may include a vinylidene fluoride polymer resin, a good solvent, a hydrophilic additive, and acetylated methylcellulose.

The vinylidene fluoride-based polymer resin may include at least one of a vinylidene fluoride homopolymer and a vinylidene fluoride copolymer. Specifically, it may contain at least one of tetrafluoroethylene, hexafluoropropylene, trifluoroethylene or a copolymer of trifluoroethylene and chlorofluorocarbon.

The vinylidene fluoride-based polymer resin may be contained in the polymer coating layer composition in an amount of 10 wt% or more and less than 20 wt%, specifically 12 wt% or more and less than 20 wt%, more specifically 15 wt% or more and less than 20 wt%. In the above content range, the hollow fiber membrane is excellent in chemical resistance and can have an appropriate pore size.

The solvent can sufficiently dissolve the vinylidene fluoride-based polymer resin contained in the composition for a polymer coating layer and can impart an appropriate viscosity required for the hollow fiber membrane.

The two solvents may be, for example, N-mentyl-2-pyrrolidone, dimethylformamide, N, N'-dimethyl acetamide, , Dimethylsulfoxide, and hexamethylphosphoric triamide. ≪ Desc / Clms Page number 7 >

The two solvents may be contained in the composition for the polymer coating layer in an amount of 70% by weight to 88.9% by weight, specifically 70% by weight to 85% by weight. In the above content range, the polymeric resin is sufficiently dissolved in the composition for a polymer coating layer to form a homogeneous composition.

The hydrophilic additive may have higher hydrophilicity of the hollow fiber membrane, thereby improving water treatment efficiency.

Examples of the hydrophilic additive include polyvinylpyrrolidone (PVP), ethylene glycol, polyethylene glycol (PEG), hydrophilic polymers having at least one (meth) acrylate group introduced therein, glycerol, polyacrylonitrile (PAN) Oxide (PEO) and polyvinyl acetate (PVAc).

The hydrophilic additive may be included in the composition for the polymer coating layer in an amount of 1 to 10% by weight. In the above content range, the hollow fiber membrane is excellent in water permeability.

The acetylated methylcellulose is included in the composition for a polymer coating layer to improve hydrophilicity of the hollow fiber membrane. Specifically, the hollow fiber membrane containing a vinylidene fluoride polymer has an advantage of being excellent in chemical resistance and strength, but has a disadvantage in that water permeability is low because it is a hydrophobic material. Since the composition for a polymer coating layer of the present invention contains acetylated methyl cellulose, water permeability is improved by increasing the hydrophilicity while maintaining the chemical resistance and strength of the hollow fiber membrane by the vinylidene fluoride polymer. Specifically, acetylated methylcellulose has many hydrophilic groups such as hydroxy groups, so that the hydrophilicity of the hollow fiber membrane can be improved even with a small amount, and the water permeability can be improved while maintaining the chemical resistance and strength of the hollow fiber membrane.

The acetylated methyl cellulose may be contained in the composition for the polymer coating layer in an amount of 0.1 to 5% by weight, specifically 1 to 3% by weight. In the above content range, the hollow fiber membrane is excellent in water permeability.

The composition for the polymeric support layer may include a vinylidene fluoride polymer resin, a good solvent, a plasticizer, and a hydrophilic additive.

The vinylidene fluoride-based polymer resin is substantially the same as the vinylidene fluoride-based polymer resin of the composition for a polymer coating layer. The vinylidene fluoride-based polymer resin contained in the polymer support layer composition may serve to form a support layer having excellent strength.

The vinylidene fluoride type polymer resin may be contained in the composition for the polymeric support layer in an amount of 20 wt% or more and less than 40 wt%, specifically, 25 wt% or more and less than 35 wt%. In the above content range, the hollow fiber membrane has excellent mechanical properties and pores can have an appropriate size.

The good solvent may be substantially the same as the good solvent of the composition for the polymer coating layer. The above-mentioned both polymers may be contained in the composition for the polymeric support layer in an amount of 5 to 20% by weight, specifically 5 to 15% by weight. In the above content range, the flowability of the composition, the rate of phase transition, and the pore size are appropriate.

The plasticizer can dissolve the vinylidene fluoride-based polymer resin at a high temperature. The plasticizer may have a viscosity of 300 to 4,000 cps, specifically 2,000 cps to 3,500 cps. In the case of forming the hollow fiber membrane by spinning the composition for polymer support layer containing the plasticizer having the viscosity range to the intermediate flow path of the triple spinneret, the hollow can be formed without discharging the internal coagulating solution.

The plasticizer may include at least one of a polyester plasticizer, a phthalic acid plasticizer, an adipic acid plasticizer and a trimellitic acid plasticizer. The plasticizer may be a polyester plasticizer in terms of the porosity of the hollow fiber membrane and the flowability of the spinning solution.

The polyester plasticizer may be a polyester containing a dicarboxylic acid and a diol as repeating units. The polyester plasticizer may have a weight average molecular weight of 500 to 4,000, specifically 1,500 to 3,500.

The dicarboxylic acid may be a linear and / or cyclic aliphatic dicarboxylic acid. Specifically, the dicarboxylic acid may be a linear alkylene group having 1 to 20 carbon atoms or a dicarboxylic acid containing a branched alkylene group having 3 to 20 carbon atoms. For example, the dicarboxylic acid containing a linear alkylene group having 1 to 20 carbon atoms or a branched alkylene group having 3 to 20 carbon atoms is preferably a dicarboxylic acid selected from the group consisting of ethylene dicarboxylic acid, 1,3-propane-dicarboxylic acid, Butane dicarboxylic acid, 1,4-pentanedicarboxylic acid, 1,5-pentanedicarboxylic acid, 1,6-hexanedicarboxylic acid, 3- Methyl pentane-1,4-dicarboxylic acid, 2,2,4-trimethylpentane-1,3-dicarboxylic acid, 2-ethylhexane-1 , 3-dicarboxylic acid, 2,2-diethylpropane-1,3-dicarboxylic acid, and the like, but not limited thereto.

The diol may include a linear alkylene group having 1 to 20 carbon atoms or a diol having a branched alkylene group having 3 to 20 carbon atoms. For example, the diol comprising the linear alkylene group having 1 to 20 carbon atoms or the branched alkylene group having 3 to 20 carbon atoms may be at least one member selected from the group consisting of ethylene glycol, 1,3-propane-diol, 1,3-butanediol, , 1,4-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentane-2,4-diol, 2-methylpentane- 1,3-diol, 2-ethylhexane-1,3-diol, 2,2-diethylpropane-1,3-diol, and the like.

In embodiments, the polyester-based plasticizer may be an adipic acid polyester plasticizer, but may be, for example, a polymer of adipic acid and 1,3-butanediol.

The plasticizer may be contained in the composition for the high-boiling support layer in an amount of 25 to 73.9% by weight, specifically 35 to 70% by weight. In the above content range, the composition for a polymeric support layer has a viscosity suitable for forming a hollow fiber membrane, and the hollow fiber membrane produced therefrom is excellent in water permeability and strength.

The hydrophilic additive may be substantially the same as the hydrophilic additive of the composition for a polymer coating layer, and the hollow fiber membrane may have higher hydrophilicity, thereby improving water treatment efficiency.

The hydrophilic additive may be included in the composition for the polymeric support layer in an amount of 1 to 10% by weight. In the above content range, the hollow fiber membrane is excellent in water permeability.

In another embodiment, the composition for the polymeric support layer may contain 0.1 to 5% by weight, specifically 1 to 3% by weight, of acetylated methylcellulose. In the above content range, the water permeability of the hollow fiber membrane can be improved.

The acetylated methyl cellulose may be substantially the same as that described in the composition for a polymer coating layer. Specifically, the acetylated methylcellulose serves to improve the hydrophilicity of the hollow fiber membrane. Specifically, acetylated methylcellulose has many hydrophilic groups such as hydroxy groups, so that the hydrophilicity of the hollow fiber membrane can be improved even with a small amount, and the water permeability can be improved while maintaining the chemical resistance and strength of the hollow fiber membrane.

Meanwhile, the composition for a polymer coating layer and the composition for a polymeric support layer may optionally contain additional additives (excluding the hydrophilic additives) in order to control physical properties and uses of the hollow fiber membranes to be produced and the shape and size of pores formed in the hollow fiber membrane surface or inside thereof . Additional additives may include conventional components capable of achieving this purpose, such as polyoxyethylene-polyoxypropylene block copolymer, lithium chloride (LiCl), lithium perchlorate (LiClO ₄ ), methanol, ethanol, Isopropanol, acetone, phosphoric acid, propionic acid, acetic acid, pyridine, etc. may be used singly or in combination. The additional additive may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the composition for a polymer coating layer or the composition for a polymeric support layer.

In one embodiment, the method for producing a hollow fiber membrane is characterized in that the composition for a polymer coating layer is radiated to an outer flow path of the triple spinneret, the composition for the polymer support layer is radiated to an intermediate flow path of the triple spinneret, It may not discharge the high liquid. The structure of the triple spinneret is shown briefly in Fig.

The triple spinneret can emit three kinds of spinning liquids at the same time, for example, but it is not limited thereto.

Specifically, the composition for a polymer coating layer may be stirred at 40 ° C to 80 ° C for 2 to 8 hours to spin into the outer flow path 51 of the triple spinneret. Specifically, the polymeric support layer composition may be stirred at 160 ° C. to 220 ° C. for 2 to 8 hours to radiate to the intermediate flow path 53 of the triple spinneret. Within this range, a viscosity suitable for spinning can be maintained, and uniform pores can be sufficiently formed in the hollow fiber membrane.

The hollow fiber membrane manufacturing method may not discharge the inner coagulating solution into the inner flow path of the triple spinneret. Specifically, the composition for the polymer support layer discharged from the intermediate flow path of the triple spinneret includes the plasticizer having the specific viscosity, so that the hollow can be formed without the internal coagulating solution discharge.

The solidification can be carried out in a solution containing non-solvent. The solidification is a step of forming a film according to the coagulation treatment. Specifically, the discharged composition for a polymer coating layer and the composition for a polymeric support layer (hereinafter referred to as a spinning solution) can be precipitated in a non-solvent to form internal pores and to produce a membrane. The coagulation bath may include a non-solvent that does not dissolve the solvent and the polymer membrane.

For example, various organic solvents, water, glycols and the like can be used as the non-solvent, and a coagulating solvent in which water, water and an organic solvent or water and glycol are mixed can be used. More specifically, Water can be used. The temperature of the non-solvent may be from 0 캜 to 90 캜, specifically from 5 캜 to 50 캜.

In another embodiment, the hollow fiber membrane manufacturing method may further include a step of stirring the composition for a polymer coating layer or the composition for a polymeric support layer, and then removing bubbles before discharging the polymer composition to a spinning channel. Unexpected large pore formation can be prevented by removing air bubbles before the composition is discharged.

In another embodiment, the hollow fiber membrane manufacturing method may further include the step of solidifying and then stretching.

The stretching may be dry stretching, and in this case, the mechanical strength and water permeability are improved. The dry stretching may be performed by an inter-roll stretching method, a heating roll stretching method, a compression stretching method or a tenter stretching method or a batch jig stretching method.

The inter-roll stretching method refers to a method of stretching the coagulated composition through two pairs of rollers having different rotational speeds. In addition, the batch jig stretching method refers to a method in which a PVDF hollow fiber membrane precursor is fixed on a pair of jigs, and one or both of the pair of jigs is stretched by moving the gap between the two jigs. The heating roll stretching method, the compression stretching method, or the tenter stretching method can be carried out by a conventionally known method.

Specifically, the dry stretching may be performed by passing the coagulated composition between two pairs of rollers having different rotational speeds. The stretching speed is 3 to 30 m / s, the stretching temperature is 10 to 50 ° C, the elongation is 30 % To 300%. Specifically, the dry stretching can be performed under the condition of an elongation of 50% to 200%. Stable stretching is possible in the above-mentioned range.

The hollow fiber membrane manufacturing method may further include washing and drying the resultant of solidifying (and / or drawing) the hollow fiber membrane. Specifically, the resultant product of the solidification (and / or stretching) step may be washed with a solvent that does not dissolve and then dried at a predetermined temperature to finally obtain a hollow fiber membrane. For washing, dichloromethane, acetone, methanol, ethanol, water and the like can be used. For example, water at 10 ° C to 90 ° C can be used. After the washing, the resultant is dried at a temperature of 10 to 200 ° C to finally produce a microporous hollow fiber membrane.

The hollow fiber membrane according to another embodiment of the present invention may be manufactured by the hollow fiber membrane manufacturing method and has a water permeability of 1,000 LMH / bar or more, for example, 1,000 LMH / bar to 4,000 LMH / bar, specifically 1,100 LMH / bar to 3,000 LMH / bar and a tensile strength of 0.7 kgf / fiber or more, for example 0.7 kgf / fiber to 3.0 kgf / fiber, specifically 1.0 kgf / fiber to 2.0 kgf / fiber.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example

Example  One

Preparation of Composition for Polymer Supporting Layer: 30 wt% of polyvinylidene difluoride (PVDF) and 54 wt% of a polyester plasticizer (polymer of adipic acid and 1,3-butanediol) were stirred and mixed at 190 캜 for 3 hours , 10% by weight of N-methyl-2-pyrrolidone, 5% by weight of polyvinylpyrrolidone (PVP) and 1% by weight of acetylated methyl cellulose (AMC) were mixed to prepare a composition for a polymeric support layer.

Preparation of a composition for a polymer coating layer: 18 wt% of polyvinylidene difluoride (PVDF) and 76 wt% of N-methyl-2-pyrrolidone were stirred and mixed at 60 DEG C for 4 hours and polyvinylpyrrolidone 5% by weight of PVP and 1% by weight of acetylated methyl cellulose (AMC) were mixed to prepare a composition for a polymer coating layer.

The polymeric coating layer composition was spun from the outer channel of the spinneret using a triple spinneret including a triple pipe and the composition for the polymeric support layer was spun from the central channel of the spinneret and discharged to a coagulation bath containing water And coagulated to prepare a preliminary hollow fiber membrane. At this time, the coagulating solution was not used in the spinneret.

The coagulated preliminary hollow fiber membrane was wound up at the downstream end through a washing bath, dipped in a dichloromethane solution for 24 hours to extract a plasticizer, and dry-drawn at a temperature of 150% at a room temperature to prepare a hollow fiber membrane. An electron microscope image (400 times) of the support layer of the hollow fiber membrane and the cross section of the coating layer is shown in FIG. 3, and an electron microscope image (5,000 times) of the cross section of the support layer is shown in FIG.

Example  2

A hollow fiber membrane was prepared in the same manner as in Example 1, except that the composition for the polymeric support layer did not contain acetylated methylcellulose (AMC) and the polyester plasticizer was used in an amount of 55% by weight.

Comparative Example  One

A hollow fiber membrane was prepared in the same manner as in Example 1, except that a single membrane was formed from the composition for a polymeric support layer of Example 1.

Comparative Example  2

A hollow fiber membrane was prepared in the same manner as in Example 1, except that a single membrane was formed from the composition for a polymer coating layer of Example 1.

Property evaluation method

(1) Water permeability (LMH / bar): The hollow fiber membrane was placed in an acrylic tube of 20 cm, and the membrane was potted by using an epoxy, and the permeate flow rate was measured per hour to measure the water permeability according to the membrane area. In the measurement of pure water permeability, a pressure of 1 bar was applied and measured by a dead-end filtration method.

(2) Tensile strength (kgf / fiber): One strand of the hollow fiber membrane was immersed in a Grip using an Instron, and the tensile strength was measured while pulling the hollow fiber membrane at a rate of 50 mm / min.

(3) Average pore size (㎛): The hollow fiber membrane was attached to the stage where the SEM could be taken using carbon tape. Then, when the hollow fiber membrane was attached to the specimen stage, there was no gap between the carbon tape, the sample and the stage. After mounting on the stage, gold coating was performed using ion-coater. The average pore size of the outer surface (coating layer) was measured using SEM and is shown in Table 1 below.

Example Comparative Example One 2 One 2 Water permeability (LMH / bar) 1510 1330 2300 720 Tensile strength (kgf / fiber) 1.45 1.21 1.7 0.30 Average pore size of coating layer (unit: 占 퐉) 0.03 0.03 0.17 0.03

As shown in Table 1, it can be seen that the hollow fiber membranes of Examples 1 and 2 of the present invention are superior in ultrafiltration membrane grade (UF grade) and superior in mechanical strength and water permeability. On the other hand, in Comparative Example 1 in which a single membrane was formed only as a composition for a polymer support layer, Comparative Example 2 in which a single membrane was formed only as a composition for a polymer coating layer and Comparative Example 2 in which a membrane for an ultrafiltration membrane (UF grade) It can be seen that the tensile strength is lowered.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are in all respects illustrative and not restrictive.

Claims (9)

A polymeric support layer forming an inner peripheral surface; And
A polymer coating layer surrounding the support layer and forming an outer circumferential surface;
A hollow fiber membrane having a multi-layer structure,
Wherein the polymer support layer has an average pore size of more than 0.05 占 퐉 and not more than 0.15 占 퐉, wherein the polymeric vinylidene fluoride polymer resin is contained in an amount of 20 to 40% by weight, 5 to 20% by weight of a good solvent, 25 to 73.9% by weight of a plasticizer, 10% by weight of a polymeric support layer,
Wherein the polymer coating layer comprises a polymer coating layer comprising at least 10 wt% of a vinylidene fluoride polymer resin and less than 20 wt% of a vinylidene fluoride polymer resin, 70 to 88.9 wt% of a good solvent, 1 to 10 wt% of a hydrophilic additive and 0.1 to 3 wt% of acetylated methylcellulose Lt; RTI ID = 0.0 > of: < / RTI >
The hollow fiber membrane according to claim 1, wherein the average pore size of the polymer coating layer is 0.01 탆 to 0.05 탆.
The hollow fiber membrane according to claim 1, wherein the thickness of the polymer support layer is 70% to 98% of the total thickness.
The hollow fiber membrane according to claim 1, wherein the hollow fiber membrane has a water permeability of 1,000 LMH / bar or more and a tensile strength of 0.7 kgf / fiber or more.
A composition for a polymer coating layer comprising 10 to 20% by weight of a vinylidene fluoride polymer resin, 70 to 88.9% by weight of a good solvent, 1 to 10% by weight of a hydrophilic additive and 0.1 to 3% by weight of acetylated methylcellulose. And
A polymeric support layer composition comprising 20 wt% or more and less than 40 wt% of a vinylidene fluoride polymer resin, 5 to 20 wt% of a good solvent, 25 to 73.9 wt% of a plasticizer, and 1 to 10 wt% of a hydrophilic additive;
Is radiated through a triple spinneret to solidify the hollow fiber membrane.
6. The method of claim 5,
Wherein the composition for the polymeric support layer further comprises 0.1 to 5% by weight of acetylated methylcellulose.
The composition for a polymer coating layer according to claim 5, wherein the composition for a polymer coating layer is radiated to an outer flow path of the triple spinneret, and the polymeric support layer composition is radiated to an intermediate flow path of the triple spinneret,
Wherein the coagulating solution is not discharged to the inner flow path.
The method for producing a hollow fiber membrane according to claim 5, further comprising: after the solidification, stretching.
A hollow fiber membrane produced by the method of any one of claims 5 to 8, wherein the hollow fiber membrane has a water permeability of 1,000 LMH / bar or more and a tensile strength of 0.7 kgf / fiber or more.

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