KR101619403B1 - Preparation method of hollow fiber membrane and hollow fiber membrane - Google Patents

Abstract

The present invention relates to a polymer resin composition for forming a substrate; A polymer resin composition for surface coating; And spinning a spinning solution including a bore solution into a wet coagulation bath, and a polymer base material including a vinylidene fluoride type polymer resin and an organic phosphate; And a surface coating layer formed on the polymer substrate and having fine pores having a cross-sectional diameter of 5 nm to 300 nm formed on the surface.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hollow fiber membrane,

The present invention relates to a hollow fiber membrane and a hollow fiber membrane. More particularly, the present invention relates to a hollow fiber membrane which has high strength and excellent chemical resistance and which realizes a stable and efficient water treatment by realizing a high water permeability, .

The asymmetric membrane developed by Loeb and Sourirajan in 1962 is now widely used in the gas and water industry. The asymmetric separator is composed of a dense layer and a porous support layer at the upper part. The asymmetric separator has better material transferring power than the symmetric separator and has a long lifetime advantage. Generally, a dry-wet phase transition method is widely used for the asymmetric membrane production process. In the dry-wet manufacturing process, the polymer is mixed with a solvent or diluent to make a homogeneous polymer dope solution, and the resulting polymer dope solution is dried through a nozzle to expose the solution to the air, ), And phase transition occurs in the coagulation bath to form a separation membrane. The prepared membranes are washed, dried, and post treated to final hollow fiber membranes.

In general, the asymmetric membrane has a dense layer on its surface, which is formed by solidification while increasing the concentration of the polymer in the dope solution. The concentration of the polymer in the dope solution during the spinning process is as follows. When the solvent of the first dope solution is volatilized in the air gap, the solvent of the polymer solution rapidly escapes from the second coagulation tank and the concentration of the polymer increases at the instantaneous interface. Finally, When a solvent having a surface tension is used, a thin dense layer is formed from a variety of causes.

However, the Dense layer acts as an active layer in gas separation, but is disadvantageous in terms of water flux for water treatment applications. Recently, studies have been conducted to suppress the dense layer of water treatment hollow fiber membrane, to add a large number of pore forming agents to the dope solution, to replace the coagulation tank binder, to minimize the air gap, and the like.

Korean Patent Publication No. 2013-0040621 Korea Patent Publication No. 2012-0001970

The present invention provides a hollow fiber membrane which has high strength and excellent chemical resistance, and which realizes a high water permeability and enables stable and efficient water treatment.

The present invention also relates to a method for producing a hollow fiber membrane which has high strength and excellent chemical resistance and which realizes high water permeability and enables stable and efficient water treatment.

In the present specification, the polymeric resin composition for substrate formation comprising 10 to 70% by weight of a vinylidene fluoride type polymer resin, 1 to 70% by weight of a good solvent, 1 to 75% by weight of a poor solvent and 0.001 to 5% by weight of an organic phosphate ; 5 to 75% by weight of a vinylidene fluoride type polymer resin, 0.5 to 20% by weight of a hydrophilic polymer additive and 20 to 90% by weight of a good solvent; And a bore solution containing one solvent selected from the group consisting of N-methylpyrrolidone and dimethylacetamide and a non-solvent, and spinning the spinning solution into a wet coagulation bath. A manufacturing method can be provided.

Also, in the present specification, a polymer base material containing a vinylidene fluoride-based polymer resin and an organic phosphate; And a surface coating layer formed on the polymer substrate and having fine pores having a cross-sectional diameter of 5 nm to 300 nm formed on the surface, wherein the surface coating layer has a diameter of 500 mu m to 5,000 mu m and a diameter of 50 mu m to 500 mu m Desert can be provided.

Hereinafter, a hollow fiber membrane manufacturing method and hollow fiber membrane according to a specific embodiment of the present invention will be described in detail.

As described above, according to an embodiment of the present invention, a composition comprising 10 to 70 wt% of a vinylidene fluoride polymer resin, 1 to 70 wt% of a good solvent, 1 to 75 wt% of a poor solvent, and 0.001 to 5 wt% A polymer resin composition for forming a substrate; 5 to 75% by weight of a vinylidene fluoride type polymer resin, 0.5 to 20% by weight of a hydrophilic polymer additive and 20 to 90% by weight of a good solvent; And a bore solution containing one solvent selected from the group consisting of N-methylpyrrolidone and dimethylacetamide and a non-solvent, and spinning the spinning solution into a wet coagulation bath. A manufacturing method can be provided.

Therefore, the inventors of the present invention conducted a study on the production of a hollow fiber membrane, and found that when a polymer resin composition for forming a substrate containing an organic phosphate is used together with a vinylidene fluoride polymer resin, a good solvent and a poor solvent, The present inventors have confirmed through experiments that the water treatment can be realized stably and efficiently by realizing a high water permeability while greatly improving the chemical properties, and completed the invention.

By using the organic phosphate, the crystallinity and the crystallization rate of the polymer resin included in the hollow fiber membrane can be promoted and the crystal size can be miniaturized, thereby improving the strength and chemical resistance of the hollow fiber membrane.

In addition, when a polymer resin composition for surface coating is used together with the polymer resin composition for forming a substrate, a predetermined surface coating layer may be formed on the substrate of the hollow fiber membrane to be produced. The water permeability of the hollow fiber membrane can be improved while securing the mechanical properties of the hollow fiber membrane at an equivalent level or more.

As described later, fine pores having a cross-sectional diameter of 5 nm to 300 nm can be formed on the surface of the surface coating layer, and a hollow tube type Pores can be formed.

In the method for producing a hollow fiber membrane according to one embodiment, the hollow fiber membrane may be prepared by spinning a spinning solution containing the base polymer resin composition, the polymer resin composition for surface coating, and a bore solution into a wet coagulation bath .

The air gap, which is the length of the hollow fiber membrane exposed to the outside during the movement of the spinning solution from the spinneret or the like to the coagulating bath, can be appropriately adjusted according to the physical properties and applications of the final hollow fiber membrane. For example, 15 cm.

The wet coagulation bath is filled with water, and the wet coagulation bath or the water that is supplied to the wet coagulation bath can be maintained at a temperature of -10 ° C to 60 ° C.

In order to have a proper shape of the hollow fiber membrane, the bore solution is positioned at the innermost portion of the spinning solution at the time of spinning the spinning solution into the wet coagulation bath, and the outermost portion of the spinning solution A polymer resin composition for surface coating may be placed. The polymer resin composition for forming a substrate may be radiated in a state of being positioned between an innermost portion of the spinning solution and an outermost portion of the spinning solution.

Specifically, the step of spinning the spinning solution into a wet coagulation bath may be performed using a triple spinneret including a triple pipe. At this time, a bore solution is radiated from one kind of pipe located at the innermost side of the spinneret, the polymer resin composition for surface coating is emitted from another pipe located at the outermost side of the spinneret, The polymeric resin composition for substrate-forming may be radiated from another one of the tubes located between the innermost and outermost sides of the spinneret.

In order to spin the spinning solution into a wet coagulation bath, the spinning nozzle may be connected to the polymer solution transfer line and the nozzle, and may be connected to a metering pump or nitrogen gas for pushing the polymer solution.

When the spinning liquid is stabilized, it is pushed by a metering pump of a constant flow rate or a valve of nitrogen gas is opened to apply a constant pressure. The discharge rate is determined by the pressure of nitrogen gas which is usually used, Can be adjusted according to the physical properties and properties of the desert, and can be discharged at a speed of, for example, 1 cm to 30 cm per second.

A polymeric resin composition for forming a substrate; A polymer resin composition for surface coating; And the bore solution may be from 1 to 5: 1: 1 to 5. If the amount of the polymeric resin composition for forming a substrate or the bore solution is excessively small or excessive, the shape, size, or specific physical properties of the hollow fiber membrane to be finally produced may not be suitable for use in water treatment or the like.

On the other hand, by heating the polymer resin composition for substrate-forming at 50 to 175 ° C or 100 to 171 ° C, the polymer resin composition for forming base resin is converted into a polymer spinning solution that can be used for producing hollow fiber membranes can do.

If the heating temperature of the polymer resin composition for forming a substrate is too low, the viscosity of the polymer resin composition may not be sufficiently lowered so that spinning may be difficult. If the spinning solution obtained by applying a low heating temperature is used, Pores having a size that is not sufficiently formed, minute uniform, or not suitable may be formed. If the heating temperature of the polymer resin composition for forming a substrate is too high, the components contained in the polymer resin composition for producing a hollow fiber membrane may be decomposed.

The polymer resin composition for substrate-forming and the polymer resin composition for surface coating may each include a vinylidene fluoride-based polymer resin.

The vinylidene fluoride-based polymer resin means a polymer or copolymer containing repeating units of vinylidene fluoride. Specifically, the vinylidene fluoride-based polymer resin is a vinylidene fluoride homopolymer, a vinylidene fluoride copolymer, or a mixture thereof. .

The vinylidene fluoride copolymer includes a copolymer of a vinylidene fluoride monomer and other monomers such as tetrafluoroethylene, propylene hexafluoride, ethylene trifluoride, or ethylene trifluoride chloride.

The vinylidene fluoride-based polymer resin may have a weight average molecular weight of 100,000 to 1,000,000, or 250,000 to 800,000, or 300,000 to 600,000. If the weight average molecular weight of the vinylidene fluoride type polymer resin is too small, the mechanical properties and chemical resistance of the hollow fiber membrane to be produced can not be sufficiently secured. If the weight average molecular weight of the vinylidene fluoride type polymer resin is too large, the viscosity of the spinning solution becomes too high, making it difficult to produce a hollow fiber membrane.

The organic phosphate included in the substrate-forming polymer resin composition may include an aromatic phosphate ester metal salt. The aromatic phosphate ester metal salt means a phosphate salt of a phosphoric acid ester having at least one aromatic group having 6 to 20 carbon atoms.

The aromatic phosphoric acid ester metal salt may include a compound represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R _{6 ,} R ₇ and R ₈ may be the same or different and are each a hydrogen or a straight or branched alkyl group having 1 to 10 carbon atoms , X is a straight or branched alkylene group having 1 to 5 carbon atoms, and n is 1 or 2. When n is 1, M is an alkali metal, and when n is 2, M is an alkaline earth metal or hydroxyaluminum.

R ₁ , R ₃ , R _{6 ,} and R ₈ are each a straight or branched alkyl group having 1 to 10 carbon atoms, and R ₂ , R ₄ , R _5, and R ₇ may be hydrogen .

Specific examples of the compound of formula (1) include compounds of the following formulas (2) to (6).

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

The polymer resin composition for forming a substrate may contain 0.001 wt% to 5 wt%, or 0.01 wt% to 3 wt% of an organic phosphate. If the content of the organic phosphate is too small, the action or effect of the use of the phosphate may be insignificant. In addition, if the content of the organic phosphate is too large, suspended solids that do not dissolve in the spinning solution may be generated, and the hollow fiber membrane may be broken in the spinning process, or uneven or large bubbles may be generated in the hollow fiber membrane.

The polymer resin composition for forming a substrate may contain 10 to 70% by weight or 25 to 50% by weight of the vinylidene fluoride polymer resin.

If the content of the vinylidene fluoride-based polymer resin in the substrate-forming polymer resin composition is too small, it is difficult to secure sufficient mechanical properties and chemical resistance of the hollow fiber membrane to be produced or formation of the polymer base material of the hollow fiber membrane is not easy . If the content of the vinylidene fluoride polymer resin in the polymer resin composition for forming a substrate is too large, the rate of phase transition of the components contained in the polymer resin composition for forming a substrate may be significantly lowered or the pore formed in the hollow fiber membrane The size may become very small and water treatment performance may be deteriorated.

The amount of solvent (good-solvent) is an amount having a polyfluorinated vinylidene can be used a known solvent that the dengye resin can be dissolved, and 21 to 27 MPa ^1/2 of the Total solubility parameter and 130 to disconnect point of 230 ℃ It is preferable to select a solvent.

Specific examples of the usable positive solvent include N-methyl-2-pyrrolidone, dimethylformamide, N, N'-dimethylacetamide (N, N'- dimethyl acetamide, dimethyl sulfoxide, hexamethylphosphoric triamide, or a mixture of two or more thereof.

The polymer resin composition for forming a substrate may contain 1 to 70% by weight or 10 to 60% by weight of a good solvent. If the content of the good solvent in the polymer resin composition for forming a substrate is too low, the flowability of the polymer resin composition for forming a substrate or the spinning solution using the polymer resin composition may be lowered and the kneading temperature should be increased accordingly. If the content of the positive solvent in the polymer resin composition for forming a substrate becomes too high, the polymer resin composition for forming a substrate or the hollow fiber membrane produced by the heat-induction phase separation method using the spinning solution using the polymer resin composition, The size of the pores formed in the pores may be significantly increased, so that the water treatment performance may be deteriorated.

The poor solvent does not have a solubility in a polymer at room temperature and has a property of dissolving a polymer at a high temperature. In a thermally induced phase transfer (TIPS) process, a poor solvent forms pores in a polymer separator, And the function of lowering the melting point of the polymer can be realized.

Specific examples of the poor solvent include dibutyl phthalate, dimethyl phthalate, dioctyl sebacate, dioctyl adipate, gamma-butylolactone, Propylene carbonate, or a mixture of two or more thereof.

The polymer resin composition for forming a substrate may contain 1 to 75 wt% or 10 to 60 wt% of a poor solvent. If the amount of the poor solvent in the polymer resin composition for forming a substrate is too small, the porosity of the hollow fiber membrane may be lowered or the pore may not be properly formed, thereby reducing the permeate flow rate. If the content of the poor solvent in the polymer resin composition for forming a substrate is too large, the flowability of the polymer resin composition for forming a substrate or the spinning solution using the polymer resin composition may be lowered and thus the kneading temperature must be increased, In the thermally induced phase separation method using the resin composition or the spinning solution using the resin composition, the phase transition rate is excessively high, or the pore formed in the hollow fiber membrane to be manufactured is very large, so that the water treatment performance may be deteriorated.

The polymer resin composition for forming a substrate may further contain additives such as a plasticizer, a use agent, or a dispersant.

Meanwhile, the polymer resin composition for surface coating may contain 1 to 20% by weight of a vinylidene fluoride-based polymer resin. The vinylidene fluoride-based polymer resin contained in the polymer resin composition for surface coating may form a coating layer having a high porosity.

If the content of the vinylidene fluoride-based polymer resin in the polymer resin composition for surface coating is too small, the mechanical properties or chemical resistance of the surface coating layer of the hollow fiber membrane to be finally produced may be deteriorated. In the polymer resin composition for surface coating, If the content of the ternary polymer resin is too high, it is not easy to form suitable pores in the surface coating layer of the hollow fiber membrane to be finally produced, and the water permeability may be lowered.

The good solvent contained in the polymer resin composition for surface coating may also be a solvent known to dissolve the polyvinylidene fluoride resin. The total solubility parameter of 21 to 27 MPa ^{1/2 and} the total solubility parameter of 130 It is preferable to select a good solvent having a boiling point of 230 to < RTI ID = 0.0 > 230 C. < / RTI > The polymer resin composition for surface coating may contain 20 to 90 wt% or 25 to 80 wt% of a good solvent.

Specific examples of the usable positive solvent include N-methyl-2-pyrrolidone, dimethylformamide, N, N'-dimethylacetamide (N, N'- dimethyl acetamide, dimethyl sulfoxide, hexamethylphosphoric triamide, or a mixture of two or more thereof.

Meanwhile, the polymer resin composition for surface coating may contain 0.5 to 20% by weight of a hydrophilic polymer additive. The hydrophilic polymer enables the surface coating layer formed on the surface of the hollow fiber membrane to have a higher hydrophilicity, thereby realizing a high water permeability and enabling stable and efficient water treatment.

If the content of the hydrophilic polymer additive in the polymer resin composition for surface coating is too low, the surface coating layer may not have sufficient hydrophilicity. Also, if the content of the hydrophilic polymer additive in the polymer resin composition for surface coating is too high, the mechanical properties and chemical resistance of the surface coating layer may be lowered.

The hydrophilic polymer additive may include a hydrophilic polymer having at least one (meth) acrylate group introduced therein. Specific examples of the hydrophilic polymer additive include polymethyl methacrylate (PMMA) having a weight average molecular weight of 50,000 to 200,000 .

The bore solution forms an inner hole of the hollow fiber membrane to be produced and determines the inner hollow fiber membrane morphology. In general, the Bohr solution is a mixture of solvent and non-solvent for the polymer.

The bore solution may contain 40 to 70% by weight of one solvent selected from the group consisting of N-methylpyrrolidone and dimethylacetamide, and the balance of non-solvent. If one of the solvents selected from the group consisting of N-methylpyrrolidone and dimethylacetamide is used in an amount of more than 70% by weight, the inner wall of the separator may be dissolved. If the solvent is used in an amount exceeding 40% by weight, the internal porosity of the hollow fiber membrane may be deteriorated.

The non-solvent may be water, ethylene glycol, an alcohol solvent, a ketone solvent, a polyalkylene glycol, or a mixture of two or more thereof.

Meanwhile, the method for producing the hollow fiber membrane may further include a step of recovering the resultant product by the wet coagulation bath and immersing the resultant in a water bath at 40 ° C to 80 ° C.

When the hollow fiber membrane is dried in the air, surface pores may be clogged by surface tension. In order to prevent such a phenomenon, the produced hollow fiber membrane is impregnated with a predetermined aqueous solution, for example, a glycerol aqueous solution (30 to 60 wt%, titration: 50 wt%) for about 20 to 40 hours, It can be rough.

According to another embodiment of the present invention, there is provided a polymer substrate comprising a vinylidene fluoride-based polymer resin and an organic phosphate; And a surface coating layer formed on the polymer substrate and having fine pores having a cross-sectional diameter of 5 nm to 300 nm formed on the surface, wherein the surface coating layer has a diameter of 500 mu m to 5,000 mu m and a diameter of 50 mu m to 500 mu m Desert can be provided.

The hollow fiber membrane provided through the above-described method of producing a hollow fiber membrane can realize a stable and efficient water treatment by realizing a high water permeability while having high strength and excellent chemical resistance. Particularly, the polymer base material included in the hollow fiber membrane of the embodiment may include a polymer resin having a high degree of crystallinity and a relatively small crystal size, thereby improving the strength and chemical resistance of the hollow fiber membrane.

In addition, a predetermined surface coating layer may be formed on the polymer substrate of the hollow fiber membrane. This surface coating layer can secure the mechanical properties such as break strength of the hollow fiber membrane equal to or higher than that of the hollow fiber membrane, .

The hollow fiber membrane may have an outer diameter of 500 μm to 5,000 μm and a thickness of 50 μm to 500 μm.

Micropores having a cross-sectional diameter of 5 to 300 nm may be formed on the surface of the surface coating layer, and hollow tube-type pores formed in the polymer base material in a direction outside the surface coating layer may be formed in the surface coating layer have.

More specifically, the vinylidene fluoride-based polymer resin and the organic phosphate include the above-mentioned contents in the method of producing the hollow fiber membrane of the embodiment.

The surface coating layer may have a thickness of 20 to 150 mu m.

The surface coating layer may include a vinylidene fluoride-based polymer resin and a hydrophilic polymer additive.

The hydrophilic polymer additive may include a hydrophilic polymer having at least one (meth) acrylate group introduced therein.

The surface coating layer includes the vinylidene fluoride-based polymer resin and the hydrophilic polymer additive described above in detail in the method of producing the hollow fiber membrane of the embodiment.

The hollow fiber membrane of this embodiment may have a net permeation rate of 250 to 1,500 L / m < 2 > * hr (60 cm Hg).

According to the present invention, there can be provided a hollow fiber membrane having a high strength and excellent chemical resistance, realizing a high water permeability and stably and efficiently water treatment, and a method for producing such a hollow fiber membrane.

1 is a cross-sectional view of the hollow fiber membrane of Example 1. Fig.
Fig. 2 shows a cross section of the hollow fiber membrane of Comparative Example 1. Fig.
Fig. 3 shows fine spherical structures contained in the hollow fiber membrane support of Example 1. Fig.
Fig. 4 shows pores on the surface of the surface coating layer of the hollow fiber membrane of Example 1. Fig.

The invention will be described in more detail in the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[ Example  And Comparative Example : Production of hollow fiber membrane]

< Example 1 >

 40% by weight of polyvinylidene fluoride, 50% by weight of gamma-butyrolactone, 9.7% by weight of dimethylacetamide (DMAc), and 50% by weight of phosphoric ester salts (sodium 2,2'-methylenebis- (CAS No. 85209-91-2)) was added to the solution, followed by mixing at 150 ° C for 6 hours to prepare a base polymer resin composition (solution).

Then, 12 wt% of polyvinylidene fluoride, 10 wt% of polyvinyl pyrrolidone (PVP), 5 wt% of polymethyl methacrylate (PMMA), and 73 wt% of dimethylacetamide (DMAc) , And a polymer resin composition (solution) for surface coating was prepared.

Dimethylacetamide (DMAc): A bore solution of ethylene glycol (EG) at a weight ratio of 6: 4 at room temperature was prepared.

A bore solution is radiated from one kind of tube located at the innermost side of the spinneret using a triple spinneret including a triple tube and is discharged from one of the other tubes located at the outermost side of the spinneret, The polymer resin composition for coating was spun and the polymer resin composition for substrate-forming was spun from another one of the tubes located between the innermost and outermost sides of the spinneret. The distance from the spinneret to the coagulation bath was 4 cm, and the temperature inside the coagulation bath was kept at 5 캜.

At this time, the spinning discharge amount (g / min) is the polymer resin composition for substrate formation; A polymer resin composition for surface coating; And bore solution was 3: 1: 2.

The nozzle for spinning the polymer resin composition for substrate-forming was maintained at 140 DEG C, the nozzle for emitting the bore solution was kept at room temperature, and the nozzle through which the polymer resin composition for surface coating was spinning was kept at room temperature Respectively.

The resultant product was recovered by the wet coagulation bath and immersed in a water bath at 60 DEG C for about 24 hours, and then immersed in ethanol for about 24 hours. The resultant was washed with water and naturally dried to prepare a hollow fiber membrane (outer diameter: 1300 탆, film thickness: 300 탆).

 < Example  2>

A hollow fiber membrane was prepared in the same manner as in Example 1 except that the inside of the coagulation bath was kept at 30 캜. (Outer diameter of hollow fiber membrane: 1300 mu m, thickness of membrane: 300 mu m)

 < Example  3>

A hollow fiber membrane was produced in the same manner as in Example 1, except that the content of the vinylidene fluoride in the substrate-forming polymer resin composition was 30% by weight and gamma-butyrolactone was 60% by weight. Respectively. (Outer diameter of hollow fiber membrane: 1250 mu m, thickness of membrane: 250 mu m)

< Example 4 >

A hollow fiber membrane was prepared in the same manner as in Example 1, except that the content of the polymeric resin composition for forming a substrate was 50 wt% of polyvinylidene fluoride and 40 wt% of gamma-butyrolactone. Respectively. (Outer diameter of hollow fiber membrane: 1400 탆, film thickness: 350 탆)

< Comparative Example 1 >

A hollow fiber membrane was prepared in the same manner as in Example 1, except that 10% by weight of dimethylacetamide (DMAc) was used without using an aromatic phosphate ester metal salt. (Outer diameter of hollow fiber membrane: 1300 mu m, thickness of membrane: 300 mu m)

< Comparative Example 2 >

10% by weight of dimethylacetamide (DMAc) was used in the polymer resin composition for forming a substrate without using an aromatic phosphate ester metal salt, and that 10 parts by weight of the polymeric resin composition for surface coating was used without using polymethyl methacrylate (PMMA) A hollow fiber membrane was prepared in the same manner as in Example 1 except that 78% by weight of dimethylacetamide (DMAc) was used. (Outer diameter of hollow fiber membrane: 1300 mu m, thickness of membrane: 300 mu m)

< Comparative Example 3 >

40% by weight of polyvinylidene fluoride, 50% by weight of gamma-butyrolactone, 9.7% by weight of dimethylacetamide (DMAc), and 50% by weight of phosphoric ester salts (sodium 2,2'-methylenebis- (CAS No. 85209-91-2)) was added to the solution, followed by mixing at 150 ° C for 6 hours to prepare a base polymer resin composition (solution).

Dimethylacetamide (DMAc): A bore solution of ethylene glycol (EG) at a weight ratio of 6: 4 at room temperature was prepared.

The base polymer resin composition and the bore solution were transferred to a spinneret using a gear pump device and spun into a coagulation bath. The distance from the spinneret to the coagulation bath was about 4 cm and the temperature inside the coagulation bath was maintained at 5 ° C.

At this time, the spinning-out amount is the polymer resin composition for substrate-forming; And bore solution was 1: 2.

In addition, the nozzle through which the substrate-forming polymer resin composition was spinning was maintained at 140 ° C, and the nozzle through which the bore solution was radiated was kept at room temperature.

The resultant product was recovered by the wet coagulation bath and immersed in a water bath at 60 DEG C for about 24 hours, and then immersed in ethanol for about 24 hours. The resultant was washed with water and naturally dried to prepare a hollow fiber membrane (outer diameter: 1300 탆, film thickness: 300 탆).

[ Experimental Example : Measurement and observation of physical properties of hollow fiber membrane]

Experimental Example 1 : DSC  Measure

In order to completely remove the internal solvent of the hollow fiber membrane sample obtained in the above Examples and Comparative Examples, it was dried in an oven at 120 ° C for 24 hours.

In order to remove the thermal history of the initial specimen, the temperature of the specimen was raised to 210 ° C and the specimen was allowed to stand for 10 minutes. Then, the specimen melted at 210 ° C / Lt; / RTI &gt;

Under these conditions, the crystallization temperature (Tc), heat (J / g) and crystallization time (sec) are measured

DSC Crystallization temperature (Tc, 占 폚) Calories (J / g) Crystallization time (sec) Comparative Example 1 120 44.3 77 Example 1 128 49.2 68

** The results of Example 1 above are the results of measurements on the substrate of the hollow fiber membrane

As shown in Table 1, in Example 1, it was confirmed that the crystallization temperature (Tc) and the amount of heat were relatively high and the crystallization time was relatively short. This is because the addition of the aromatic phosphoric acid ester metal salt to the substrate-forming polymer resin composition results in shortening of the chain length of the PVDF polymer and a decrease in the molecular weight distribution, resulting in favorable formation of crystals.

On the contrary, Comparative Example 1 has a lower crystallization temperature and lower heat amount than Example 1, and consequently it has been confirmed that the phase transition time is long.

Experimental Example 2 : Severity  Measure

About 200 mm of the hollow fiber membrane obtained in the above Examples and Comparative Examples was prepared. The dimensions of the cross section of the hollow fiber membrane were measured by SEM or optical microscope.

Then, using the INSTRON equipment, the hollow fiber membrane was stuck to the upper and lower sample grips, and the effective length between the grip and grip was 100 mm. The experiment speed was 50 mm / min. And the breaking strength was determined.

Experimental Example 3 : Water permeability  Measure

Six hollow fiber membrane samples having an effective membrane length of 10 cm were prepared from the hollow fiber membranes obtained in the above Examples and Comparative Examples, respectively, and then inserted into a tubular tube and fixed with epoxy to prepare a dead-end type membrane module. Distilled water was introduced into the membrane module at a pressure of 1 kg / cm 2, and the amount of water permeated to the outside was measured inside the hollow fiber membrane.

At this time, the area of the separation membrane was calculated as the inner diameter of the hollow fiber, and the pure water permeability per unit area was calculated. A total of five modules were fabricated and the water permeability was determined by measuring the average value.

Experimental Example 4 : Water permeability  Measure

The contact angle of the membrane surface was measured with a contact angle meter for the hollow fiber membranes obtained in the above Examples and Comparative Examples.

Specifically, the surface of the dried hollow fiber membrane was placed on a sample table to be measured, and after a fine droplet of a predetermined size (0.5)) was contacted on the flat surface of the hollow fiber membrane, the angle between the drop surface and the membrane surface was measured as an initial contact angle Respectively. The measurement is repeated five times to calculate the initial contact angle average.

division Cutting strength (gf / fil.) Water permeability
(L / m ² hr) Contact angle
(°) Example 1 700 650 59 Example 2 650 550 70 Example 3 630 580 60 Example 4 400 750 59 Example 5 820 300 59 Comparative Example 1 860 8 76 Comparative Example 2 500 450 68

Experimental Example 5 : SEM Of hollow fiber membranes

The hollow fiber membranes obtained in the above Examples and Comparative Examples were dried and SEM images were measured. Specifically, the specimens of the hollow fiber membranes obtained in the above Examples and Comparative Examples were subjected to liquid nitrogen treatment, and then the specimen was broken, not the knife cutting, to observe the cross section.

The cross section of the hollow fiber membrane of Example 1 is as shown in Fig. As shown in Fig. 1, the structure of the hollow fiber membrane composed of the coating layer formed by the non-solvent induction phase transition and the support formed by the thermal induction phase transition is confirmed. In addition, the coating layer has a cross-section of a finger-like structure. This finger structure is formed as the solvent-nonmetallic exchange rate rapidly advances in the non-solvent induction phase transition.

Fig. 3 shows fine spherical structures contained in the hollow fiber membrane support of Example 1. Fig. These microscopic spherical structures are spherical structures formed by the growth of crystals which predominantly proceeds with the solid-liquid phase transition in the heat induced phase transformation process.

Fig. 4 shows pores on the surface of the surface coating layer of the hollow fiber membrane of Example 1. Fig. As shown in FIG. 4, it was confirmed that pores having a cross-sectional diameter of about 0.025 μm were formed in the surface coating layer.

Fig. 2 shows a cross section of the hollow fiber membrane of Comparative Example 1. Fig. In Comparative Example 1, a hollow fiber membrane was produced using only a heat induced phase change process. As shown in FIG. 2, the upper layer of the hollow fiber membrane of Comparative Example 1 is formed with a dense layer, the lower layer is composed of crystal structures, and the fracture strength of the hollow fiber membrane due to the dense layer But the water permeability seems to decrease.

Claims (23)

A polymer resin composition for forming a substrate comprising 10 to 70% by weight of a vinylidene fluoride polymer resin, 1 to 70% by weight of a good solvent, 1 to 75% by weight of a poor solvent and 0.001 to 5% by weight of an organic phosphate;
5 to 75% by weight of a vinylidene fluoride type polymer resin, 0.5 to 20% by weight of a hydrophilic polymer additive and 20 to 90% by weight of a good solvent; And
A step of spinning a spinning solution containing a solvent selected from the group consisting of N-methylpyrrolidone and dimethylacetamide, and a bore solution containing a non-solvent, into a wet coagulation bath. Way.
The method according to claim 1,
The bore solution is located at the innermost portion of the spinning solution,
Wherein the polymer resin composition for surface coating is placed at an outermost portion of the spinning solution.
3. The method of claim 2,
Wherein the step of spinning the spinning solution into a wet coagulation bath is carried out using a triple spinneret including a triple tube.
The method of claim 3,
A bore solution is radiated from one kind of tube located on the innermost side of the spinneret,
The polymeric resin composition for surface coating is radiated from another one of the tubes located at the outermost side of the spinneret,
And the polymer resin composition for substrate-forming is radiated from another one of the tubes located between the innermost and outermost sides of the spinneret.
The method according to claim 1,
Wherein the vinylidene fluoride-based polymer resin comprises at least one selected from the group consisting of a vinylidene fluoride homopolymer and a vinylidene fluoride copolymer.
The method for producing a hollow fiber membrane according to claim 1, wherein the vinylidene fluoride-based polymer resin has a weight average molecular weight of 100,000 to 1,000,000.
The method according to claim 1,
The two solvents may be selected from N-methyl-2-pyrrolidone, dimethylformamide, N, N'-dimethyl acetamide, Wherein the hollow fiber membrane comprises at least one selected from the group consisting of dimethyl sulfoxide and hexamethylphosphoric triamide.
The method according to claim 1,
The poor solvent may be at least one selected from the group consisting of dibutyl phthalate, dimethyl phthalate, dioctyl sebacate, dioctyl adipate, gamma-butylolactone and propylene carbonate propylene carbonate, and the like.
The method according to claim 1,
Wherein the organic phosphate comprises an aromatic phosphate ester metal salt.
10. The method of claim 9,
Wherein the aromatic phosphate ester metal salt comprises a compound represented by the following formula (1): &lt; EMI ID =
[Chemical Formula 1]

In Formula 1,
R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R _6, R ₇ and R ₈ may be the same or different and each is hydrogen or a straight chain alkyl group having 1 to 2 carbon atoms, Branched alkyl group,
X is a straight chain alkyl group having 1 to 2 carbon atoms or a linear or branched alkylene group having 3 to 5 carbon atoms,
n is 1 or 2,
When n is 1, M is an alkali metal, and when n is 2, M is an alkaline earth metal or hydroxy aluminum.
The method according to claim 1,
Wherein the hydrophilic polymer additive comprises a hydrophilic polymer having at least one (meth) acrylate group introduced therein.
The method according to claim 1,
Wherein the hydrophilic polymer additive comprises polymethyl methacrylate (PMMA) having a weight average molecular weight of 50,000 to 200,000.
The method according to claim 1,
Wherein the bore solution comprises 40 to 70% by weight of one solvent selected from the group consisting of N-methylpyrrolidone and dimethylacetamide, and the balance of non-solvent.
The method according to claim 1,
Wherein the non-solvent comprises at least one member selected from the group consisting of water, ethylene glycol, alcohol solvents, ketone solvents, and polyalkylene glycols.
The method according to claim 1,
A polymeric resin composition for forming a substrate; A polymer resin composition for surface coating; And a bore solution in a mass ratio of 1: 5: 1: 1 to 5.
The method according to claim 1,
And recovering the resultant product by the wet coagulation bath and immersing the resultant in a water bath at 40 ° C to 80 ° C.
A polymer substrate including a vinylidene fluoride-based polymer resin and an organic phosphate; And
And a surface coating layer formed on the polymer substrate and having fine pores having a cross-sectional diameter of 5 nm to 300 nm formed on the surface,
A hollow fiber membrane having an outer diameter of 500 mu m to 5,000 mu m and a thickness of 50 mu m to 500 mu m.
18. The method of claim 17,
Wherein the organic phosphate comprises an aromatic phosphate ester metal salt.
18. The method of claim 17,
Wherein the surface coating layer comprises a vinylidene fluoride-based polymer resin and a hydrophilic polymer additive.
20. The method of claim 19,
Wherein the hydrophilic polymer additive comprises a hydrophilic polymer having at least one (meth) acrylate group introduced therein.
18. The method of claim 17,
Wherein the surface coating layer has a thickness of 10 to 150 占 퐉.
18. The method of claim 17,
And a hollow tube type pore formed in the polymer coating layer in a direction outward of the surface coating layer is formed in the surface coating layer.
18. The method of claim 17,
A hollow fiber membrane having a net permeation rate of 250 to 1,500 L / m 2 * hr (60 cm Hg).

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