WO2016195282A1

WO2016195282A1 - Method for preparing hollow fiber membrane and hollow fiber membrane

Info

Publication number: WO2016195282A1
Application number: PCT/KR2016/005168
Authority: WO
Inventors: 김정은; 배수경; 박범진; 최하림
Original assignee: 롯데케미칼 주식회사
Priority date: 2015-06-03
Filing date: 2016-05-16
Publication date: 2016-12-08
Also published as: CN107635651A; KR20160142696A; KR101775137B1

Abstract

The present invention relates to a method for preparing a hollow fiber membrane, the method comprising a step for spinning a spinning liquid into a wet type coagulation bath, the spinning liquid containing: a polymeric resin composition for substrate formation; a polymeric resin composition for surface coating, containing a vinylidene fluoride-based polymer resin, a good solvent, and graphene oxide; and a bore solution, to a hollow type polymeric substrate containing a vinylidene fluoride-based polymer resin, to a hollow fiber membrane formed on the hollow type polymeric substrate and comprising a porous surface coating layer.

Description

【Specification】

[Name of invention]

Manufacturing method and hollow fiber membrane of hollow fiber membrane

Technical Field

Cross Citation with Related Application (s)

This application claims the benefit of priority based on Korean Patent Application No. 10-2015-0078769 dated June 3, 2015, and all content disclosed in the literature of that Korean patent application is incorporated as part of this specification. The present invention relates to a method for manufacturing a hollow fiber membrane and a hollow fiber membrane, and more particularly, to a hollow fiber membrane and a method for producing such a hollow fiber membrane, which have high strength and excellent chemical resistance and enable high water permeability to enable stable and efficient water treatment. It is about.

[Technique to become background of invention]

Asymmetric membranes, developed by Loeb and Sourirajan in 1962, are now widely used in the gas and water industries. The asymmetric separator is composed of an upper dense layer and a porous support layer, and has a superior material transfer force and a long service life than the symmetric separator. In general, a dry-wet phase transition method is widely used in the asymmetric membrane manufacturing process. Dry—wet manufacturing process is performed by mixing the polymer with a solvent or diluent to make a uniform polymer dope solution, and then drying the wet polymer dope solution through the nozzle to dry air. Precipitates and becomes a phase transition in the arch, forming a separator. The prepared membrane is made into a final hollow fiber membrane by washing, drying and post-treatment.

In general, the asymmetric membrane has a dense layer on its surface, which is formed by solidification with increasing concentration of the polymer in the dope solution. When the concentration of the polymer in the dope solution during the spinning process is as follows. In the case where the first dope solution is volatilized in the air gap, the second solvent of the polymer solution is rapidly When the polymer concentration increases at the interface at the moment of exiting, finally, a solvent having a higher surface tension than the polymer is used, and a thin dense layer is formed on the surface from various causes.

However, the membrane surface dense layer (Dense l ayer) acts as an active layer in gas separation, but has a disadvantageous structure in water permeability (Fl ux) for water treatment applications. Recently, research on suppressing the surface dense layer (Dense l ayer) of water-treated hollow fiber membranes has been conducted, such as adding a large number of pore-forming agents to the dope solution, replacing the non-solvent non-solvent, and minimizing the air gap. .

[Content of invention]

Problem to be solved

The present invention is to provide a hollow fiber membrane having a high strength and excellent chemical resistance and high water transmittance to enable a stable and efficient water treatment.

In addition, the present invention relates to a method for producing a hollow fiber membrane having high strength and excellent chemical resistance and high water transmittance to enable stable and efficient water treatment.

[Measures of problem]

In the present specification, a polymer resin composition for forming a substrate including a vinylidene fluoride polymer resin, a good solvent and a poor solvent; A polymer resin composition for surface coating containing vinylidene fluoride polymer resin, a good solvent, and graphene oxide; And a bore solution comprising one solvent and a non-solvent selected from the group consisting of N-methylpyrrolidone and dimethylacetamide; spinning a spinning solution comprising a wet coagulation bath into a wet coagulation bath. Manufacturing methods may be provided.

In the present specification, the hollow polymer substrate containing a vinylidene fluoride polymer resin; And a porous surface coating layer formed on the hollow polymer substrate and comprising vinylidene fluoride-based polymer resin and graphene oxide, and having an outer diameter of 500 / im to 5,000 ^ and a thickness of 50 to 500 / m. A hollow fiber membrane having a may be provided.

Hollow fiber membrane manufacturing method according to a specific embodiment of the invention and The enlarged membrane will be described in more detail. As described above, according to an embodiment of the present invention, a polymer resin composition for forming a substrate including a vinylidene fluoride polymer resin, a good solvent and a poor solvent; A polymer resin composition for surface coating containing vinylidene fluoride polymer resin, a good solvent, and graphene oxide; And a bore solution comprising a solvent and a non-solvent selected from the group consisting of N-methylpyrrolidone and dimethylacetamide. A method of producing may be provided.

Accordingly, the present inventors have conducted research on the production of hollow fiber membranes, and improved mechanical properties of the hollow fiber membrane having a double layer structure manufactured using a polymer resin composition for surface coating including vinylidene fluoride polymer resin, a good solvent, and graphene oxide. In addition, it was confirmed through experiments that high water permeability can be implemented to realize stable and efficient water treatment and completed the invention.

In particular, it is possible to accelerate the crystallization degree and crystallization rate of the polymer resin in the porous surface coating layer of the hollow fiber membrane is produced and refining the grain size, thereby improving the like of the hollow fiber membrane strength and chemical resistance in accordance with in accordance with the ^'using the oxidation graphene In addition, due to the high hydrophilicity of graphene oxide can increase the water transmittance and water treatment efficiency.

As will be described later, the porous surface coating layer may be formed on the surface of the micropores having a cross-sectional diameter of 5ππι to 300ππι, and also inside the surface coating layer of the hollow tube type formed in the polymer coating substrate in the outer direction of the surface coating Pores may be formed.

There is no big limitation on the type or shape of graphene oxide that can be used in the method for producing the hollow fiber membrane, and there is no big limitation on graphene oxide, and conventional graphene oxide, for example, about O. lO to lO. Graphene oxide having a single layer structure having a thickness of about Onm can be used without particular limitation. Then, in order to prepare such graphene oxide, the Scotch tape is adhered to graphite oxide (graphi te ox i de) and then detached and adhered to the tape surface. To obtain graphene oxide in the form of sheet, pulverized graphite is added to an acidic solution containing an oxidizing agent, oxidized and sonicated to obtain graphene oxide, or after immersing the graphite and electrode plate in the electrolyte solution. A method of applying a power source to form a graphene oxide layer and dropping the same may be used.

In addition, the specific shape or size of the graphene oxide is not limited, for example, 0.05 nm to ΙΟΟππι, or 0.01 ηηι to lO. Graphene oxide having a cross sectional diameter of Onm can be used. The cross-sectional diameter may be determined as the longest length of the cross-sectional diameters of graphene oxide.

When using graphene oxide having an excessively large cross-sectional diameter, mechanical properties of the hollow fiber membrane to be manufactured may be degraded, and the internal pore structure may not be suitable for water treatment. In addition, when using graphene oxide having a cross-sectional diameter too small, the synergistic effect of using the above-described graphene oxide may not be achieved.

In the method of manufacturing the hollow fiber membrane of the embodiment, the hollow fiber membrane may be manufactured by spinning a spinning solution including the polymer resin composition for forming the substrate, the polymer resin composition for surface coating, and a bore solution in a wet unggot. have.

The air gap (ai r gap), which is a length exposed to the outside while the spinning liquid is discharged from the spinning nozzle and moved to the arch, may be appropriately adjusted according to the properties and uses of the hollow fiber membrane to be finally manufactured. cm to 15 cni.

The wet coagulation bath is filled with water, and the wet coarse bath or water staying therein may be maintained at a temperature of -10 to 60 ^° C.

In order to have the hollow fiber membrane has a suitable shape, in the step of spinning the spinning solution in a wet submerged bath, the bore solution is located at the innermost part of the spinning solution during spinning, the outermost part of the spinning solution The surface coating polymer resin composition may be located. The polymer resin composition for forming the substrate may be spun in a state located between the innermost part of the spinning solution and the outermost part of the spinning solution. Specifically, the step of spinning the spinning solution in a wet unggojo may be performed using a triple spinneret including a triple pipe. In this case, a bore solution is spun from one tube located at the innermost side of the spinneret, and the polymer resin composition for surface coating is spun from another tube located at the outermost side of the spinneret. The polymer resin composition for forming a substrate may be spun from another tube located between the innermost and outermost sides of the spinneret.

In order to spin the spinning solution in a wet submerged bath, the spinning nozzle may be connected to a polymer solution transfer line and a nozzle, and may also be connected to a metering pump or nitrogen gas to push the polymer solution.

When the spinning solution is stabilized, it must be pushed with a fixed flow pump of a constant flow rate or a valve of nitrogen gas is applied to apply a constant pressure. The discharge speed is determined by the pressure of nitrogen gas that is commonly used. It can be adjusted according to the properties or properties of the desert, ^l can be discharged at a rate of lcm to 30cm per second.

The polymer resin composition for forming the substrate; Polymer resin compositions for surface coating; And a weight ratio of the bore solution may be 0.5 to 5: 1: 0.5 to 5. When the amount of the polymer resin composition for forming the substrate or the bore solution is too small or excessive, the shape and size or specific physical properties of the final hollow fiber membrane may not be suitable for use in water treatment. The polymer resin composition for forming the substrate; Polymer resin compositions for surface coating; And the weight ratio of the bore solution may be defined as the spinning rate (g / min) of each composition or solution, and the like.

On the other hand, the polymer spinning solution that can be used for the hollow fiber membrane production of the polymer resin composition for forming the substrate through the step of heating the polymer resin composition for forming the substrate to 50 ^° C to 175 ^° C, or 100 ^° C to 171 ^° C You can switch to the form.

When the heating temperature of the polymer resin composition for forming the base material is too low, the viscosity of the polymer resin composition may not be sufficiently low, so that spinning may be difficult. When the spinning solution obtained by applying a low heating temperature is used, In the hollow fiber membrane to be manufactured, pores may not be sufficiently formed or pores of uneven and inappropriate size may be formed. In addition, when the heating temperature of the polymer resin composition for forming the substrate is too high, components included in the polymer resin composition for manufacturing the hollow fiber membrane may be decomposed.

In the manufacturing method of the hollow fiber membrane, located on the innermost side of the spinneret

The bore (bore) the temperature of the solution in one type of pipe is 5 ^° C to 50 ^° C, wherein the surface coating temperature of the polymer resin composition at the other one kinds located in the outermost side of the spinneret tube 5 ^° C to 50 ^° C, the temperature of the polymer resin composition for forming the substrate in another one tube located between the innermost and outermost side of the spinneret may be 50 ^° C to 175 ^° C. In order to satisfy the above-mentioned temperature conditions, heating means, temperature holding means or cooling means can be used without great limitation.

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

The vinylidene fluoride polymer resin refers to a polymer or copolymer including a vinylidene fluoride repeat unit, and specifically, the vinylidene fluoride polymer resin may be a vinylidene fluoride homopolymer, a vinylidene fluoride copolymer, or a mixture thereof. May comprise a compound.

The vinylidene fluoride copolymers include copolymers of vinylidene fluoride monomers and other monomers such as tetrafluoride ethylene, hexahexapropylene propylene, tribromethylene ethylene or ethylene trifluoride chloride.

The vinylidene fluoride polymer resin may have a weight average molecular weight of 100, 000 to 1, 000, 00, or 250, 000 to 800, 000, or 300, 000 to 600, 000. If the weight average molecular weight of the vinylidene fluoride polymer resin is too small, mechanical properties, chemical resistance, etc. of the hollow fiber membrane to be manufactured may not be sufficiently secured. In addition, when the increase average molecular weight of the vinylidene fluoride polymer resin is too large, the viscosity of the spinning solution becomes too high, making it difficult to produce a hollow fiber membrane.

The polymer resin composition for forming the substrate is the vinylidene fluoride polymer resin. 10 to 70% by weight, or 25 to 50% by weight. When the content of the vinylidene fluoride-based polymer resin in the polymer resin composition for forming the substrate is too small, it is difficult to sufficiently secure the mechanical properties or chemical resistance of the hollow fiber membrane to be produced or the formation of the polymer substrate of the hollow fiber membrane may not be easy. Can be. In addition, when the content of the vinylidene fluoride polymer resin in the polymer resin composition for forming the substrate is too large, the phase transition rate of the components included in the polymer resin composition for forming the substrate is greatly lowered or pores formed in the hollow fiber membrane to be manufactured. The size is so small that water treatment performance can be degraded.

The good solvent may be a solvent known to be capable of dissolving polyvinylidene fluoride resin, and may include a good solvent having a total solubility parameter of 21 to 27 MPa ^1/2 and a boiling point of 130 to 23 CTC. It is desirable to choose.

Specific examples of the usable good solvent include N-methyl-2-pyrrol idone, dimer 1 dimethylformamide, Ν, Ν'-dimethyl acetamide (Ν, N'-dimethyl acetamide), dimethyl sulfoxide, hexamethylphosphoric triamide, or a combination of two or more thereof.

The polymer resin composition for forming the substrate may include 1 to 70% by weight of a good solvent, or 10 to 60% by weight. When the content of the polymer resin composition increasing solvent for forming the substrate is too low, the flowability of the polymer resin composition for forming the substrate or the spinning solution using the same may be lowered, and accordingly, the temperature of the stirring should be increased. In addition, when the content of the good solvent in the polymer resin composition for forming the substrate is too high, in the thermally induced phase separation method using the polymer resin composition for forming the substrate or the spinning solution using the same, the phase transition rate is excessively increased or produced in the hollow fiber membrane The pores formed are very large in size, which can degrade water treatment performance.

The poor solvent (poor-solvent) has a characteristic that does not have a dissolving ability to the polymer at room temperature and has a solubility of the polymer at high temperature, the poor solvent in the thermal induction phase transition (TIPS) process forms the pores of the polymer membrane, Improving the flowability of the spinning solution, it is possible to implement the function of lowering the melting point of the polymer.

Specific examples of the poor solvent include dibutyl phthalate, dimethyl phthalate, dioctyl sebacate, dioctyl adipate, and gamma butyro. Lactone (gama-butylol actone), propylene carbonate (propyl ene carbonate) or a combination of two or more thereof.

The polymer resin composition for forming the substrate may include 1 to 75% by weight of the poor solvent, or 10 to 60% by weight. If the content of the polymer solvent composition increasing solvent for forming the substrate is too small, the porosity of the hollow fiber membrane may be lowered or the pores may not be formed properly, so that the permeate flow rate may be reduced. In addition, when the content of the poor solvent in the polymer resin composition for forming the substrate is too large, the flowability of the polymer resin composition for forming the substrate or the spinning solution using the same may be lowered, and accordingly, the temperature of the balance should be increased or the polymer for forming the substrate may be reduced. In the thermally induced phase separation method using the resin composition or the spinning solution using the same, the phase transition rate is excessively high or the pores formed in the manufactured membrane are very large in size, thereby degrading water treatment performance.

Meanwhile, the surface coating polymer resin composition may include 5 to 90% by weight of vinylidene fluoride-based polymer resin, or 10 to 50% by weight. The vinylidene fluoride polymer resin included in the polymer coating composition for surface coating may serve to form a coating layer having high porosity.

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

A good solvent included in the surface coating polymer resin composition may also use a solvent known to dissolve a polyvinylidene fluoride-based resin, and a Tota solubi li ty of 21 to 27 MPa ^1/2 . parameter And a good solvent having a boiling point of from 130 to 230 ^° C. is preferred. The surface coating polymer resin composition may include 5 to 90% by weight or 20 to 90% by weight, or 25 to 80% by weight of a good solvent.

Specific examples of the usable good solvents include N-methyl-2-pyrrolidone (N-ment y 1-2-pyr ro 1 i done), dimethyl foramide (Dimethyl for 悲 lide), Ν, Ν'- Dimethyl acetamide (N, N'-dimethyl acet amide), dimethyl sulfoxide, dimethylmethyl phosphate triamide, or a combination of two or more thereof.

On the other hand, the surface coating polymer resin composition may comprise 0.001% by weight increase to 5% by weight of graphene oxide. The hydrophilic polymer makes the surface coating layer formed on the surface of the hollow fiber membrane have higher hydrophilicity, and prevents the formation of macromolecule crystals in the porous surface coating layer to be finally manufactured, thereby realizing a high water permeability to enable stable and efficient water treatment. Let's do it.

In addition, the polymer coating composition for surface coating is 0.1 to 3 parts by weight of the graphene oxide relative to 100 parts by weight of the vinylidene fluoride polymer resin, or

And 0.4 to 2 parts by weight.

When the content of graphene oxide in the surface coating polymer resin composition is too low, the surface coating layer may not have sufficient hydrophilicity, and macromolecule crystals may be excessively generated in the final surface prepared porous surface coating layer. In addition, when the content of the hydrophilic polymer additive in the surface coating polymer resin composition is too high, mechanical properties or chemical resistance of the surface coating layer may be rather reduced.

Since the graphene oxide is not dissolved in the good solvent, it is preferable to disperse it uniformly through a predetermined method.

Accordingly, the surface coating polymer resin composition may be a dispersion in which the vinylidene fluoride polymer resin and graphene oxide are dispersed in the good solvent.

Used in the process of forming the polymer coating composition for the surface coating Possible dispersion methods are not particularly limited and are, for example, commonly known dispersants, in particular poly vinyl alcohol, poly vinyl chloride, poly vinyl pyrrol idone. , Polyethylene glycol, gelatin, starch, sodium polyacrylate, carboxymehylcel lulose,

Hydroxyethy 1 eel luose, sodium dodecyl sulfate, tetramethylene ammonium bromide, dioctyl sodium sul fosuccinate, Cetyltrimethyl ammonium bromide or a combination of two or more thereof may be used.

In addition, the hollow fiber membrane manufacturing method of the embodiment may further comprise the step of forming a polymer coating composition for surface coating comprising the step of adding the vinylidene fluoride-based polymer resin after dispersing the graphene oxide in the good solvent. have.

The bore solution forms an inner hole of the hollow fiber membrane to be manufactured, and serves to determine the prepared morphology of the hollow fiber membrane. Bore solutions are generally used in combination with a solvent and a nonsolvent for the polymer. On the other hand, the bore solution is 40 to one solvent selected from the group consisting of N-methylpyridone and dimethylacetamide

And 70% by weight and residual amount of nonsolvent. Using more than 70% by weight of one solvent selected from the group consisting of N-methylpyridone and dimethylacetamide can dissolve the inner wall of the separator. In addition, the solvent

When used in less than 40% by weight may reduce the internal porosity of the hollow fiber membrane.

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

The polymer resin composition for forming the substrate and the polymer resin composition for surface coating are selected from the group consisting of a hydrophilic additive and an inorganic metal salt.

It may further comprise one or more. According to the further use of such a hydrophilic additive, the polymer resin composition for forming the substrate and the polymer for surface coating The substrate and the surface coating layer respectively prepared from the resin composition may have higher hydrophilicity, thereby improving the water treatment performance of the thickening film. In addition, according to the use of the inorganic metal salt, the substrate and the surface coating layer respectively prepared from the polymer resin composition for forming the substrate and the polymer resin composition for surface coating may have higher mechanical properties and pores of uniform size may be formed. have.

The hydrophilic additive is polyvinylpyridone (PVP), ethylene glycol, polyethylene glycol (PEG), a hydrophilic polymer having one or more (meth) acrylate groups introduced, glycerol, polyacrylonitrile (PAN), polyethylene oxide (PE0) and it may include one selected species ^"or more compounds from the group consisting of polyvinyl acetate (PVAc).

The inorganic metal salt may include at least one compound selected from the group consisting of lithium chloride, sodium chloride calumum and magnesium chloride. On the other hand, the manufacturing method of the thickening membrane may further comprise the step of immersing in the tank of io ° C to 8 (rc to recover the result of the spinning by the wet coagulation bath.

In addition, the method for producing a thickening film further comprises the step of immersing the solvent containing at least one selected from the group consisting of ethylene glycol, alcohol solvents, ketone solvents and polyalkylene glycol, the resultant spinning in the wet unggogi It may include.

When the prepared hollow fiber membrane is dried in air, surface pores may be blocked by surface tension. The hollow fiber membrane prepared to prevent this phenomenon is impregnated with a predetermined aqueous solution, for example, glycerol in an aqueous solution (30-60 wt%, titration: 50 ^%) for about 20 to 40 hours, and then taken out and dried in air. You can go through the process. On the other hand, according to another embodiment of the invention, a hollow polymer substrate including a vinylidene fluoride polymer resin; And a porous surface coating layer formed on the hollow polymer substrate and comprising a vinylidene fluoride-based polymer resin and graphene oxide, and having an outer diameter of 500 kPa to 5,000 / and an outer diameter of 50 // m to 500. A hollow fiber membrane having a thickness can be provided.

The hollow fiber membrane provided through the above-described method of manufacturing a hollow fiber membrane can realize stable and efficient water treatment by implementing high water permeability while having high strength and excellent chemical resistance. In particular, the polymer substrate included in the hollow fiber membrane of the embodiment may include a polymer resin having a high crystallinity and a relatively small crystal size, thereby improving the strength, chemical resistance, hydrophilicity, and water treatment performance of the hollow fiber membrane. . In addition, a predetermined surface coating layer may be formed on the polymer substrate of the hollow fiber membrane, and the surface coating layer may ensure mechanical properties such as breaking strength of the hollow fiber membrane to be equal to or higher than the same, while improving the water permeability of the hollow fiber membrane. You can.

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

The hollow polymer substrate including the vinylidene fluoride polymer resin may include spherical particles of vinylidene fluoride polymer resin having a diameter of 0.01 /./ m to 0.01 / mi to 2 μs. In addition, the hollow polymer substrate may include a structure in which two or more vinylidene fluoride polymer resin spherical particles are continuously connected.

That is, when the polymer substrate includes a structure in which two or more of the above-described porous resin particles are continuously connected, the polymer substrate may be a porous polymer substrate including an air gap due to a space between the porous resin particles.

The porous surface coating layer of the manufactured hollow fiber membrane may be formed by non-solvent induced phase transition to form a large pore of f i nger-ike structure. Specifically, the porous surface coating layer may be formed on one or more surfaces of the fine pores having a cross-sectional diameter of 0.0005 to 30, and the length of the surface coating layer is formed in the polymer substrate in the direction of the outer surface coating layer 0.0005 卿The pores of the hollow tube type of 30 to 30, 0.001 to 10 can be formed.

The diameter of the pores formed in the porous surface coating layer may be defined as the longest length of the pores identified in the cross section of the porous surface coating layer. The cross section of the pores formed in the porous surface coating layer can be confirmed through a device such as SEM. In addition, the shape of the pores formed in the porous surface coating layer is also not limited significantly, the cross section of the pores formed in the porous surface coating layer is a circle. It may have an ellipse or polygonal shape. The porous surface coating layer is the vinylidene fluoride polymer resin

100 parts by weight of the graphene oxide may include 0.1 to 3 parts by weight, or 0.4 to 2 parts by weight.

When the content of graphene oxide is too low compared to the vinylidene fluoride polymer resin in the porous surface coating layer, the porous surface coating layer may not have sufficient hydrophilicity, and the macromolecular crystals may be excessive in the porous surface coating layer. In addition _{, when} the content of the hydrophilic polymer additive is too high in the porous surface coating layer compared to the vinylidene fluoride-based polymer resin, mechanical properties or chemical resistance of the porous surface coating layer may be rather reduced.

More specific information about the vinylidene fluoride-based polymer resin and graphene oxide includes the above-described details in the method of manufacturing the hollow fiber membrane of the embodiment.

The surface coating layer may have a thickness of 20 to 150 / iDi.

Each of the hollow polymer substrate and the porous surface coating layer may further include at least one selected from the group consisting of a hydrophilic additive and an inorganic metal salt. Specific examples of such hydrophilic additives and inorganic metal salts are as described above.

As described above, the hollow fiber membrane can implement improved water treatment performance, for example 160 L / m ^! * hr (60 cmHg) or more, or 500 L / m ^! It may have a water permeability of * hr (60 cmHg) or more. .

【Effects of the Invention】

According to the present invention, there can be provided a hollow fiber membrane and a manufacturing method of such a hollow fiber membrane having high strength and excellent chemical resistance and high water transmittance and hydrophilicity to enable stable and efficient water treatment. [Brief Description of Drawings]

Figure 1 shows a 50 times magnified photograph of the cross section of the hollow fiber membrane prepared in Example 1.

Figure 2 shows an enlarged 300 times photograph of the cross section of the hollow fiber membrane prepared in Example 1.

[Specific contents to carry out invention]

The invention is explained in more detail in the following examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

Examples and Comparative Examples: Preparation of Hollow Fiber Membranes

40% by weight polyvinylidene fluoride (PVDF) ᅳ 25% by weight of gamma-butyrolactone (Y-butyrolactone), 10% by weight of N-methyl-2-pyrrol idone (NMP), 10% by weight of ethylene glycol, polyvinylpyrrolidone After mixing 10% by weight of pig (PVP, Polyvinylpyrrolidone) and 5% by weight of sodium chloride, it was mixed for 3 hours at 150 ° C to prepare a polymer resin composition (solution) for substrate formation.

Then, 12 wt% polyvinylidene fluoride, 0.1 wt% Graphene Oxide, 5 wt% polyvinylpyrrolidone (PVP), 3 wt% sodium chloride (NaCl), and 79.9 wt% dimethylacetamide (DMAc) 24 hours at 50 ° C., and prepared a polymer resin composition (solution) for surface coating.

Dimethylacetamide (DMAc): A bore solution was prepared in phase silver with an ethylene glycol (EG) in an increase ratio of 65:35.

Using a triple spinneret, including a triplet, to spin a bore solution from one innermost tube of the spinneret, the surface from the other tube located at the outermost side of the spinneret The polymer resin composition for coating was spun, and the polymer resin composition for substrate formation was spun from another tube located between the innermost and outermost sides of the spinneret.

The distance from the spinneret to the unggojo was 6 cm, The interior of the coagulation bath was kept at 5 ^° C. In addition, the nozzle for spinning the polymer resin composition for forming the substrate was maintained at 140 ^° C, the nozzle for spinning the bore solution was maintained at room temperature, the nozzle for spinning the polymer resin composition for surface coating is room temperature Was maintained. At this time, the radiation discharge amount (g / min, (RPM)) is the polymer resin composition for forming the substrate; Polymer resin compositions for surface coating; And the weight ratio of the bore solution was set to 2.4: 1: 1 2.4 (12: 5: 12).

The resultant which was spun into the wet uncoated bath was recovered and immersed in a 60 ^° C. water bath for about 24 hours, and then ethane was immersed in a mixed solution of 1: 1 weight ratio of glycerol for about 24 hours. Then, the resultant was washed with water and dried naturally to prepare a hollow fiber membrane.

A polymer resin composition for forming the substrate, wherein the spinning discharge amount (g / min, (RPM)) is calculated; Polymer resin compositions for surface coating; And the weight ratio of the bore solution was set to 1.7: 1: 1.7 (12: 7: 12).

A polymer resin composition for forming the substrate, wherein the spinning discharge amount (g / min, (RPM)) is calculated; Polymer resin compositions for surface coating; And a weight ratio of the bore solution was 1: 1: 1 (12:12:12).

Comparative Example 1

(1) 40% polyvinylidene fluoride (PVDF), 55% by weight of gamma-butyrolactone and polyvinylpyrrolidone (PVP)

After mixing 5% by weight, a polymer resin composition (solution) for substrate formation was prepared by mixing at 150 ^° C. for 3 hours, and (2) polyvinylidene fluoride 13 weight? ¾, polyvinylpyrrolidone (PVP) 3% by weight, sodium chloride (NaCl) by 1%, 83% by weight of dimethylacetamide (DMAc) was mixed at 50 ^° C for 24 hours, and the polymer resin composition for surface coating (solution Example 2 and except that In the same manner, a thick film was prepared.

Comparative Example 2

13 wt% polyvinylidene fluoride, 3 wt% polyvinylpyridone (PVP), 2 wt% sodium chloride (NaCl), 82 wt% of dimethylacetamide, amide (D Ac) were mixed at 50 ^° C. for 24 hours, surface coating A hollow fiber membrane was produced in the same manner as in Comparative Example 1 except that a polymer resin composition (solution) was prepared.

Experimental Example: Measurement and Observation of Physical Properties of Hollow Fiber Membrane

Experimental Example 1 Measurement of Breaking Strength

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

Then, using the INSTR0N equipment, the hollow fiber membrane was applied to the upper and lower samples Gr ip, and the effective speed between Gr ip and Gr ip was applied at 100 ms. The tensile strength at the peak was determined as the breaking strength. Experimental Example 2: Measurement of Water Transmittance

Six hollow fiber membranes ¾ of effective membrane length of 10 cm were prepared from the hollow fiber membranes obtained in Examples and Comparative Examples, respectively, and placed in tubular tubes and fixed with epoxy to prepare dead-end type separator membranes. Distilled water was put at a pressure of lkg / cii into the separator modules, and the amount of water permeated from the inside of the hollow fiber membrane to the outside was measured.

At this time, the area of the separator was calculated by the internal diameter of the hollow fiber to calculate the net permeability per unit area, and the total permeability was measured to determine the water permeability by measuring the average value. Experimental Example 3: Measurement of Contact Angle

Contact angle with respect to the expanded membrane obtained in each of the above Examples and Comparative Examples The contact surface angle of the separator was measured with a measuring instrument.

Specifically, after placing the dried hollow fiber membrane surface on the sample stage to be measured and contacting the droplet of a certain size (0.5 / 4) on the flat surface of the hollow fiber membrane, the angle formed between the droplet surface and the membrane surface is the initial contact angle. Determined. The measurement is repeated five times to calculate the initial contact angle average. Experimental Example 4: Measurement of Exclusion Rate

An aqueous solution of BSA (Bovi ne serum a bum i n) lppm was filtered through the hollow fiber membranes obtained in Examples and Comparative Examples, respectively, for 2 hours. At this time, the filtration method was applied in the same manner as the water permeability measurement method.

The exclusion rate was calculated through the difference between the concentration of the filtered BSA aqueous solution and the concentration of the initial BSA aqueous solution. At this time, the concentration was measured by UV-Vis spect rometer, UV-vis spect rometer was measured by the absorbance of the aqueous solution was converted into the concentration. The higher the measured concentration, the higher the absorbance was. Therefore, the lower absorbance value was converted into BSA concentration remaining in the solution.

The results of Experimental Examples 1 to 4 are shown in Table 1 below.

Table 11

As shown in the experimental results for the hollow fiber membranes of Examples 1 to 3 of Table 1, the thickness of the hollow fiber membrane showed a difference according to the discharge amount of the polymer resin composition (solution) for surface coating, and the thickness of the hollow fiber membrane increased as the discharge amount was increased. Showed a tendency to increase and polymer resin for surface coating discharged from nozzle As the discharge amount of the composition (solution) increases, the time for contact with air becomes shorter than that of the discharge amount, so that larger pores were formed. That is, the surface layer of the prepared membrane is formed by a non-solvent induced phase transition to form a large pore of fi nger-ike structure, the time the surface coating polymer resin composition is in contact with air is shortened f The pores of the inger-ike structure can be made larger. As the pore size increases, the permeate flow rate increases, and as shown in Table 1, the water permeability increases significantly with increasing discharge amount from 179 LMH to 1102 LMH.

In addition, it was confirmed that the hollow fiber membranes of Example 1 to 3 using the polymer coating composition for surface coating containing graphene oxide had higher hydrophilicity and improved water permeability. Due to the hydroxyl group, the water permeation of the hollow fiber membrane also appears to be due to a significant increase.

In contrast, in the case of the hollow fiber membranes of Comparative Examples 1 to 2 using the polymer coating composition for surface coating not containing graphene oxide, the water permeability and hydrophilicity of the discharge amount of the polymer coating composition for surface coating were compared with those of Example 2, which is the same. It was confirmed that the decrease. The hollow fiber membranes of Examples 1 to 3 using the surface coating polymer resin composition containing graphene oxide have a higher breaking strength than Comparative Examples 1 to 2, and specifically, the discharge amount of the surface coating polymer resin composition is the same. When comparing Example 2 and Comparative Examples 1 and 2, it was confirmed that the breaking strength was greatly improved.

It acts as a kind of nucleating agent, graphene oxide present in the surface layer of the manufactured hollow film to grow a large number of fine polymer crystals while preventing the growth of large polymer crystals, and thus the rigidity of the hollow fiber membrane It seems to have contributed to the increase.

On the contrary, since the graphene oxide is not included in the surface layer of the thickening films of Comparative Examples 1 to 2, the polymer crystals are greatly grown. As a result, the breaking strength or stiffness seems to be reduced. In the hollow fiber membranes of Examples 1 to 3 using the surface coating polymer resin composition containing graphene oxide, graphene oxide acts as a kind of nucleating agent, whereby a plurality of fine polymer crystals grow on the surface of the hollow fiber membrane to form a dense structure. In contrast to increasing the rejection rate, in the surface layer of the hollow fiber membranes of Comparative Examples 1 to 2, relatively large polymer crystals are present, thereby increasing the probability of the particles falling out, and greatly lowering the exclusion rate as shown in Table 1 above. The rate is shown. Experimental Example 5 Observation of the Cross-sectional Structure of Hollow Fiber Membrane Using SEM

The hollow fiber membrane of Example 1 was dried to measure the SEM image. Specifically, after the liquid nitrogen treatment of the specimens of the hollow fiber membrane obtained in Example 1, the cross section was observed by breaking the specimen rather than knife cutting.

The cross section of the hollow fiber membrane of Example 1 is as showing in FIG. 1 and FIG. As shown in FIG. 1 and FIG. 2, the structure of the hollow fiber membrane composed of the coating layer formed by the non-solvent induced phase transition and the support formed by the thermal induced phase transition is confirmed. In addition, the coating layer shows a cross section of the finger structure (Fi nger l ike st ructure). Such a finger structure is a structure formed as the solvent-non-solvent exchange rate proceeds rapidly in the non-solvent induced phase transition process.

Claims

[Claim]

[Claim 11

Polymer resin composition for base-material formation containing a vinylidene fluoride-type polymer resin, a good solvent, and a poor solvent;

A polymer resin composition for surface coating containing vinylidene fluoride polymer resin, a good solvent, and graphene oxide; And

A bore solution containing one solvent and a non-solvent selected from the group consisting of N-methylpyridone and dimethylacetamide; Manufacturing method.

,

[Claim 2]

The method of claim 1,

The surface coating polymer resin composition is a dispersion of the vinylidene fluoride-based polymer resin and graphene oxide dispersed in the good solvent, hollow fiber membrane manufacturing method.

[Claim 3]

The method of claim 1,

After dispersing the graphene oxide in the good solvent, and further comprising the step of forming a polymer coating composition for surface coating comprising the step of adding the vinylidene fluoride polymer resin, hollow fiber membrane manufacturing method.

[Claim 4]

The method of claim 1,

The bore solution is located at the innermost part of the spinning solution, and the polymer resin composition for surface coating is located at the outermost part of the spinning solution.

[Claim 5]

According to claim 1, The step of spinning the spinning solution in a wet unggojo is carried out using a triple spinneret including a triple pipe, the method of manufacturing a hollow fiber membrane.

[Claim 6]

The method of claim 5,

A bore solution is spun from one tube located at the innermost side of the spinneret,

The polymer coating composition for surface coating is spun from another tube located at the outermost side of the spinneret,

A method for producing a vapor deposition film, wherein the polymer resin composition for forming a substrate is spun from another tube located between the innermost and outermost sides of the spinneret.

[Claim 7]

The method of claim 1,

The polymer resin composition for forming the substrate includes 10 to 70% by weight of vinylidene fluoride-based polymer resin, 1 to 70% by weight of good solvent and 1 to 75% by weight of poor solvent,

The surface coating polymer resin composition may be 5 to 90% by weight of vinylidene fluoride polymer resin, 5 to 90% by weight of good solvent and 0.001% by weight of graphene oxide.

The manufacturing method of a hollow fiber membrane containing 5 weight%.

[Claim 8]

The method of claim 1,

The polymer resin composition for forming the substrate and the polymer resin composition for surface coating further include at least one selected from the group consisting of a hydrophilic additive and an inorganic metal salt, respectively.

[Claim 9]

The method of claim 8, The hydrophilic additive is polyvinylpyridone (PVP), ethylene glycol, polyethylene glycol (PEG), a hydrophilic polymer having one or more (meth) acrylate groups introduced, glycerol, polyacrylonitrile (PAN), polyethylene oxide (PE0) And at least one compound selected from the group consisting of polyvinylacetate (PVAc).

[Claim 10]

The method of claim 1,

The vinylidene fluoride polymer resin comprises at least one member selected from the group consisting of vinylidene fluoride homopolymer and vinylidene fluoride copolymer.

[Claim 111]

The method of claim 1,

The vinylidene fluoride polymer resin has a weight average molecular weight of 100,000 to 1,000,000, manufacturing method of a hollow fiber membrane.

[Claim 12]

In that U term,

The good solvent may be N-methyl- 2-pyrrolidone (N- menty 卜 2-pyrrolidone), dimethylformamide (Dimethylformamide), Ν, Ν'-dimethyl acetamide (Ν, N'-dimethyl _. Acetamide), dimethyl sulfoxide A method for producing a hollow fiber membrane, comprising at least one member selected from the group consisting of dimethylsul foxide and hexamethylphosphoric triamide.

[Claim 13]

The method of claim 1,

The poor solvent is dibutyl phthalate, dimethyl phthalate, dioctyl sebacate, dioctyl adipate, gamma-butylolactone And propylene carbonate (propyl ene carbonate) comprising at least one member selected from the group consisting of, hollow fiber membrane manufacturing method.

[Claim 14]

The method of claim 1,

The bore solution is a method for producing a hollow fiber membrane comprising 40 to 70% by weight of one solvent selected from the group consisting of N-methylpyridone and dimethylacetamide and the remaining nonsolvent.

[Claim 15]

The method of claim 1,

The non-solvent comprises at least one member selected from the group consisting of water, ethylene glycol, alcohol solvents, ketone solvents and polyalkylene glycols, a method for producing a thick film.

[Claim 16]

The method of claim 1,

The polymer resin composition for forming the substrate; Polymer resin compositions for surface coating; And the mass ratio of the bore solution is 0.5-5: 1: 10.5-5.

[Claim 17]

The method of claim 1,

Recovering the resultant spinning in the wet uncoated tank further comprising the step of immersing in a water bath of 40 ^° C to 80 ^° C, manufacturing method of a hollow fiber membrane.

[Claim 18]

The method of claim 1,

The surface coating polymer resin composition includes the graphene oxide 0.1 to 3 parts by weight relative to 100 parts by weight of the vinylidene fluoride polymer resin, Manufacturing method of hollow fiber membrane

[Claim 19]

The method of claim 1,

The graphene oxide is O. lO to lO. The hollow fiber membrane manufacturing method which has a single layer structure of about Onm thickness, and a cross-sectional diameter of 0.05 nm-ΙΟΟππι.

[Claim 20]

A vacuum polymer base material including vinylidene fluoride polymer resin; And a porous surface coating layer formed on the hollow polymer substrate and comprising a vinylidene fluoride polymer resin and graphene oxide.

A hollow fiber membrane having an outer diameter of 500 kPa to 5,000 and a thickness of 50 / Λπ-50 i.

【Claim 21】

The method of claim 20,

On the surface of the porous surface coating layer, fine pores having a cross-sectional diameter of 5nm to 300nm, the hollow fiber membrane.

[Claim 22]

The method of claim 20,

The surface coating layer has a thickness of 10 to 150, the thick film.

[Claim 23]

The method of claim 20,

The inside of the surface coating layer, characterized in that the hollow fiber membrane, characterized in that the porous tube type pores formed in the polymer coating substrate formed in the outer direction.

[Claim 24]

The method of claim 20, Each of the hollow polymer substrate and the porous surface coating layer further includes at least one member selected from the group consisting of a hydrophilic additive and an inorganic metal salt.

[Claim 25]

The method of claim 20,

The porous surface coating layer is the vinylidene fluoride polymer resin

100 parts by weight of the graphene oxide containing 0.1 to 3 parts by weight, hollow fiber membrane.

[Claim 26]

The method of claim 20,

The hollow fiber membrane, the hollow fiber membrane having a water permeability of 160 L / m ² hr or more