KR101380550B1 - Pvdf porous hollow fiber membrane and manufacturing method thereof - Google Patents

Abstract

The present invention relates to polyvinyldenfluoride (PVDF) porous hollow fiber membrane and a method for manufacturing the same and, more specifically, to a PVDF porous hollow fiber membrane capable of increasing tensile strength by preventing a finger-like macro void inside the PVDF hollow fiber membrane from generating, and capable of preventing a rupture of the membrane from generating, at the same time satisfying a high water transmittance by not obstructing pores on the exterior surface of the membrane.

Description

Polyvinylidene fluoride (PDF) porous hollow fiber membrane and manufacturing method thereof

The present invention relates to a method for producing a polyvinylidene fluoride (hereinafter, abbreviated as “PVDF”) porous hollow fiber membrane, and more particularly, a fluorine-based material used for water treatment such as wastewater treatment, water purification treatment, industrial water production, and the like. It relates to a hollow fiber membrane using PVDF.

The separation membrane technology is a highly separation technology for almost completely separating and removing the materials to be treated present in the treatment water according to the pore size, the pore distribution and the membrane surface charge of the membrane. In the water treatment field, the production of high quality drinking water and industrial water, And clean production processes related to the development of waste water treatment and reuse, and free circulation systems are expanding and are becoming one of the key technologies to be noticed in the 21st century.

The membrane for water treatment may be a hollow fiber membrane. The hollow fiber membrane has a hollow-ring shape, which is advantageous in that it has a larger membrane area per module unit than a flat membrane. If the water treatment separator has a hollow fiber membrane structure, the membrane may be cleaned by backwashing to remove sediments by passing a clean liquid in a direction opposite to the filtration direction, air scrubbing for removing sediments by shaking the membrane by introducing air bubbles into the module Can be effectively used.

Typical properties required for water treatment hollow fiber membranes include adequate porosity (number of pores) for the purpose of separation efficiency, uniform pore distribution for the purpose of improving fractionation accuracy, It is required to have an optimum pore size. In addition, chemical resistance, chemical resistance, heat resistance, and the like for chemical treatment are required as material characteristics. In addition, properties that affect the operating capability are required to have good mechanical strength to extend service life, and water permeability associated with operating costs.

Polymeric materials used in the water treatment process using membrane technology include polysulfone, polyethersulfone, polyacrylonitrile, polyethylene, polypropylene, cellulose (cellulose) actate) and polyvinyldene fluoride (hereinafter referred to as " PVDF "). In particular, in recent years, a fluorine-based polymer material having a stain resistance from an organic pollution source has been attracting attention as a water treatment separator material due to a negative charge atmosphere.

The hollow fiber membrane is a non-solvent induced phase separation (NIPS) method using a non-solvent in the manufacturing method, it is possible to form a variety of structures, particularly asymmetrical structure of the separation membrane by varying the spinning conditions, and by adding various additives Pore) It is easy to adjust the size and has the advantage of obtaining a high water permeability by giving a hydrophilization to the separator.

However, PVDF hollow fiber membranes prepared by the conventional NIPS method have a weak mechanical strength in general, and in particular, a finger-like structure and macro voids are generated inside the separator, so that the tensile strength is low. There was a problem that the fracture phenomenon occurs.

 SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned problem, and prevents the formation of finger-like macro voids inside PVDF hollow fiber membranes, thereby increasing tensile strength and preventing breakage of the membranes. It is an object of the present invention to provide a PVDF porous hollow fiber membrane and a method for manufacturing the same, which simultaneously prevent high generation and satisfy high water permeability and excellent rejection rate.

 SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems,

(1) preparing a spinning stock solution comprising polyvinylidene fluoride (PVDF), a solvent and a nonsolvent; And (2) spinning the spinning stock solution and the internal coagulant through a spinning nozzle and immersing in the external coagulation solution to form hollow fiber, wherein the difference between the solubility parameters of the solvent and the internal coagulant in the spinning stock solution is 2 MPa ^{1. It} provides a method for producing a PVDF hollow fiber membrane, characterized in that more than ^{/ 2} .

According to a preferred embodiment of the present invention, the solubility parameter difference between the solvent in the spinning stock solution and the internal coagulant may be 2 to 15 MPa ^1/2 .

According to another preferred embodiment of the present invention, the solubility of the solvent in the spinning stock solution is 18 to 35 MPa ^1/2 , the solubility of the internal coagulant may be 19 to 50 MPa ^1/2 .

According to another preferred embodiment of the present invention, the solvent is gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide, Group consisting of dibutyl phthalate, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, dioctyl sebacate and glycerol triacetate At least one selected from may be.

According to another preferred embodiment of the present invention, the non-solvent may be any one or more selected from the group consisting of polyethylene glycol, ethylene glycol, propylene glycol, diethylene glycol and propylene glycol methyl ether.

According to another preferred embodiment of the present invention, the spinning stock solution may include 180 to 400 parts by weight of the solvent and 30 to 100 parts by weight of the non-solvent based on 100 parts by weight of polyvinyl fluoride (PVDF).

According to another preferred embodiment of the present invention, the internal coagulant is gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide, Dibutyl Phthalate, Dimethyl Phthalate, Diethyl Phthalate, Dioctyl Phthalate, Dioctyl Sebacate, Glycerol Triacetate, Polyethylene Glycol , Ethylene glycol, propylene glycol, diethylene glycol, propylene glycol methyl ether and glycerin (Glycerin) may be any one or more selected from the group consisting of.

According to another preferred embodiment of the present invention, the internal coagulant is selected from the group consisting of gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) Any one or more selected from the group consisting of glycerin (Glycerin), polyethylene glycol (PEG) and diethylene glycol (DEG) may include a mixed weight ratio of 5: 5 to 9: 1.

According to another preferred embodiment of the present invention, the solvent is dimethylacetamide (DMAc) or N-methyl-2-pyrrolidone (NMP), and the internal coagulant is gamma-butyrolactone and glycerin (Glycerin) may be a mixed solution mixed at a weight ratio of 5: 5 to 9: 1.

According to another preferred embodiment of the present invention, the spinning nozzle of the step (2) is a multi-tubular spinning nozzle, discharge the spinning stock solution to the outer tube of the multi-tubular spinning nozzle, and at the same time to the multi-tubular spinning nozzle inner tube The internal coagulant can be discharged.

In addition, And a separation layer formed along the outer circumference of the hollow, wherein the separation layer forms a sponge like structure, and the pores satisfying the error range ± 50% of the average pore size are 95% or more of the total pores. It provides a PVDF hollow fiber membrane, characterized in that.

 According to a preferred embodiment of the present invention, the separation layer does not include finger-like macro voids and may have a water permeability of 500 LMH or more.

According to another preferred embodiment of the present invention, the average pore size of the separation layer may be 0.03 to 0.1 μm.

According to another preferred embodiment of the present invention, the hollow fiber membrane may have a tensile strength of 5 MPa or more.

 The PVDF porous hollow fiber membrane of the present invention increases the tensile strength by preventing the formation of finger-like macro voids inside the PVDF hollow fiber membrane, while preventing the occurrence of breakage of the membrane. It is possible to provide a PVDF porous hollow fiber membrane capable of satisfying the permeability and excellent rejection at the same time.

1 is a cross-sectional view of a double tubular nozzle for producing a PVDF porous hollow fiber membrane according to the present invention.
Figure 2 is a cross-sectional photo of the PVDF hollow fiber membrane prepared by the conventional NIPS method.
Figure 3 is a cross-sectional photo of the PVDF hollow fiber membrane prepared according to a preferred embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the accompanying drawings.

 As described above, the PVDF porous hollow fiber membrane manufactured by the conventional NIPS method has a finger-like structure and macro voids generated inside the separator, so that the tensile strength is low and breakage of the separator occurs. There was this.

Therefore, the present invention comprises the steps of: (1) preparing a spinning stock solution containing polyvinyl fluoride (PVDF), a solvent and a non-solvent; And (2) spinning the spinning stock solution and the internal coagulant through a spinning nozzle and immersing in the external coagulation solution to form hollow fiber, wherein the difference between the solubility parameters of the solvent and the internal coagulant in the spinning stock solution is 2 MPa ^{1. The} above-mentioned problem was sought by providing a method for producing a PVDF hollow fiber membrane, characterized in that it is not less than ^{/ 2} . This prevents the formation of finger-like macro voids inside the PVDF hollow fiber membrane, increasing tensile strength, and preventing the occurrence of breakage of the membrane, while maintaining high water permeability and excellent rejection rate. Can be satisfied at the same time.

 Step (1) to prepare a spinning stock solution containing a polyvinyl fluoride (PVDF), a solvent and a non-solvent.

 The polyvinylidene fluoride (PVDF) used in the production of the hollow fiber membrane of the present invention is excellent in chemical resistance against sodium hypochlorite and the like, has high heat resistance, and has a high water resistance because the skeleton is hydrophobic. The polyvinylidene fluoride used in the present invention may include a vinyldifluoride homopolymer and a vinyldifluoride copolymer. Examples of the vinyldifluoride copolymer include copolymers of vinylidene fluoride with monomers such as mono-fluoride ethylene, di-fluoride ethylene, tri-fluoride ethylene, ethylene chloride or ethylene, or monomers thereof. Most preferably, vinylidene fluoride homopolymers can be used.

The polyvinylidene fluoride (PVDF) of the present invention preferably has an average molecular weight of 200,000 to 1,000,000. If the PVDF average molecular weight is less than 200,000, it may be difficult to form a hollow fiber membrane due to a low viscosity. If the PVDF average molecular weight is more than 1,000,000, moldability may be deteriorated due to high viscosity during melting.

 The polyvinylidene fluoride (PVDF) in the present invention is mixed with a solvent and a non-solvent to prepare a spinning solution. In the present invention, the solvent means that it is possible to dissolve 5% by weight or more of the polyvinyl fluoride (PVDF) resin even at a low temperature of 40 ° C. or lower, and even if the temperature is raised to the melting point of the polyvinyl fluoride (PVDF) resin, Solvents that did not dissolve or swell were defined as nonsolvents.

The solvent is gamma butyrolactone (γ-butyrolactone), dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide, dibutyl phthalate (Dibutyl Phthalate), dimethyl phthalate ( Dimethyl phthalate, diethyl phthalate, dioctyl phthalate, dioctyl sebacate or glycerol triacetate may be used alone or in a mixed form. The furnace may be in single or mixed form, such as polyethylene glycol, ethylene glycol, propylene glycol, diethylene glycol or propylene glycol methyl ether.

 The spinning stock solution may include 180 to 400 parts by weight of the solvent and 30 to 100 parts by weight of the non-solvent, based on 100 parts by weight of polyvinylidene fluoride (PVDF).

When the solvent is less than 180 parts by weight of polyvinyl fluoride (PVDF) is not dissolved, the viscosity of the discharge liquid may be difficult to form a disadvantage, when the solvent exceeds 400 parts by weight of the concentration of PVDF polymer is lowered strength May weaken.

 In addition, when the non-solvent is less than 30 parts by weight, the porosity and porosity may be lowered, so that the water permeability may be lowered. When the non-solvent is more than 100 parts by weight, the pore size may increase, so that the water permeability may increase, but the removal rate may be lowered, and the pore size is also constant. You may not have a problem.

The mixing weight ratio of the solvent and the non-solvent is preferably 4: 1 to 6: 1, and the water permeability is increased by achieving high porosity and porosity when satisfying the mixing weight ratio range.

The spinning stock solution may be prepared by mixing at 60 to 170 ° C. If it is less than 60 ℃ may have a disadvantage that the dissolution time of the PVDF is consumed for a long time, the properties of the PVDF inherent changes, and if it exceeds 170 ℃ may change the structure of the polymer due to high heat may occur browning phenomenon.

 In step (2), the spinning solution and the internal coagulant are spun through a spinning nozzle and immersed in the external coagulant to form hollow fiber.

 The spinning nozzle of step (2) may be a multi-tubular spinning nozzle, and FIG. 1 is a cross-sectional view of the double tubular spinning nozzle 5 for discharging spinning spinning solution. The spinning solution may be injected into the outer tube 2 of the double tubular spinning nozzle 5 and the inner coagulant may be simultaneously injected into the inner tubular spinning nozzle 1. The spinning nozzle is preferably maintained at 90 to 200 ℃, if out of the temperature range may change the crystallinity of the polymer may affect the porosity and strength of the hollow fiber membrane.

The internal coagulant serves to form a hollow fiber hollow, gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide, di Dibutyl Phthalate, Dimethyl Phthalate, Diethyl Phthalate, Dioctyl Phthalate, Dioctyl Sebacate, Glycerol Triacetate, Glycerol Triacetate, Polyethylene Glycol, It may be a single or mixed form of ethylene glycol, propylene glycol, diethylene glycol, propylene glycol methyl ether, glycerin (Glycerin) and the like.

In the PVDF hollow fiber membrane manufacturing method of the present invention, by adjusting the phase separation rate by satisfying the solubility parameter difference of the solvent and the internal coagulant in the spinning stock solution to 2 MPa ^1/2 or more, finger-like structure or macro It is possible to form a sponge-like structure in which no macro voids exist, to prevent breakage of the separator that occurs when macropores are present, and to significantly increase tensile strength.

 In the present invention, the solubility parameter refers to the solubility constant of each polymer or solvent, and it can be said that a solvent having a small difference in the intrinsic solubility parameter of the polymer is easier to dissolve with the polymer. In the present invention, the conversion rate between the solvent and the internal coagulant can be controlled by using the difference in the solubility parameter between the solvent and the internal coagulant in the spinning stock solution. Thus, the finger-like structure or the macro void of the hollow fiber membrane can be controlled. Formation can be suppressed. The solubility parameter can be defined by the Hansen equation as follows:

In this formula,

[delta] = solubility parameter,

δ _d = solubility parameter by disperipon force for the solubility parameter,

δ _p = solubility parameter by dipolar intermolecular force for the solubility parameter,

δ _h = the solubility parameter of the hydrogen bonding force to the solubility parameter.

More preferably, the difference in solubility parameter between the solvent in the spinning stock solution and the internal coagulant is 2 to 15 MPa.^1/2Can be, Solubility Parameter Difference 2 MPa^1/2PVDF manufactured by NIPS if less than Finger-like macro voids having a long axis of 80 μm or more may be formed in the separator. Thus, the difference in solubility parameters in the solvents and internal coagulants listed above is 2 to 15 MPa^1/2It is preferable to use a solvent and an internal coagulant selected to satisfy the requirements, and as in the prior art, the solvent and the internal coagulant may be selected from the same material or may be 2 MPa.^1/2If the above solubility parameter difference is not satisfied, the effect of the present invention cannot be achieved.

Fig. 2 shows a difference in solubility parameter of 0 MPa using the same material as the solvent in the spinning stock solution and the internal coagulant.^1/2sign It is an enlarged photo of a PVDF hollow fiber membrane manufactured according to the conventional NIPS method. As shown in Fig. 2, the solubility parameter difference between the solvent and the internal coagulant in the spinning stock solution is 2 MPa.^1/2PVDF manufactured by NIPS if less than Finger-like macropores are formed in the separator to significantly reduce tensile strength, and the hollow fiber membrane may be broken during actual operation.

 More preferably, the solubility of the solvent in the spinning stock solution is 18 to 35 MPa while satisfying the solubility parameter difference in the above range.^1/2And the solubility of the internal coagulant is 19 to 50 MPa^1/2Days have.

 Further, the internal coagulant is any one or more selected from the group consisting of gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP), glycerin (Glycerin), polyethylene It may be a mixed solution of any one or more selected from the group consisting of glycol (PEG) and diethylene glycol (DEG), and when such a mixed solution is used as an internal coagulant, the porosity and porosity of the inner surface may be controlled and the strength may be It also has the advantage of being adjustable.

The mixed internal coagulant is preferably a mixed weight ratio of the group containing gamma butyrolactone (γ-butyrolactone) and the group containing glycerin (Glycerin) is 5: 5 to 9: 1. If it is out of the above range to prevent the pores of the inner surface to reduce the water permeability or to form a finger-like macro voids (macro voids) to significantly reduce the tensile strength, the actual disadvantages of breaking the hollow fiber membrane during operation There may be.

 In the PVDF hollow fiber membrane production method of the present invention, most preferably the solvent is dimethylacetamide (DMAc) or N-methyl-2-pyrrolidone (NMP), and the internal coagulant is gamma butylolactone (γ- butyrolactone) and glycerin (Glycerin) can be used in a mixed solution in a weight ratio of 5: 5 to 9: 1, wherein the difference in solubility parameters of the solvent and the internal coagulant is 2 to 15 MPa^1/2By satisfying It forms a sponge-like structure in which no finger-like structure or macro voids exist, and has a tensile strength of 5 MPa or more and a water permeability of 500 LMH.

A PVDF hollow fiber membrane can be formed by discharging the spinning stock solution and the internal coagulant through a spinning nozzle, then dipping them in an external coagulating solution and solidifying them. At this time, the external coagulant is not particularly limited as long as it can be mixed with the plasticizer and the internal coagulant, more preferably water, gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc), N-methyl-2- Pyrrolidone, dimethyl sulfoxide, dimethylformamide, Dibutyl Phthalate, Dimethyl phthalate, Diethyl phthalate, Dioctyl phthalate, Dioctyl sebacate ), Glycerol triacetate, polyethylene glycol, ethylene glycol, propylene glycol, diethylene glycol, isopropyl alcohol, methanol or ethanol, or the like alone or in a mixed form.

The solutions discharged from the spinning nozzle can control the micropore size and physical properties of the film by controlling the distance (air gap) to the surface of the external coagulating solution of the coagulation bath. The length of the preferred air gap may be 10 to 100 mm, more preferably 10 to 50 mm. At this time, if the distance from the discharged solution to the surface of the external coagulating solution of the coagulation bath is less than 10 mm, the distance is too close to cause coagulation at the nozzle part, which causes defects in the hollow fiber. Or eccentricity can occur

The PVDF hollow fiber membranes prepared by the above-mentioned method are hollow; And a separation layer formed along the outer circumference of the hollow, wherein the separation layer forms a sponge like structure, and the pores satisfying the error range ± 50% of the average pore size are 95% or more of the total pores. Can be.

The present invention adjusts the phase separation rate by satisfying the solubility parameter difference between the solvent in the spinning stock solution and the internal coagulant of 2 MPa ^1/2 or more, so that no sponge-like macro voids exist. (sponge-like structure) can be formed, and the breakage phenomenon of the separator that occurs when the macropores are present can be prevented, and the tensile strength can be improved to 5 MPa or more. In addition, high water permeability and excellent rejection rate of 500 LMH or more can be satisfied.

 Figure 3 is an enlarged photo of the cross section of the PVDF hollow fiber membrane according to a preferred embodiment of the present invention, the solubility parameter difference between the solvent in the spinning stock solution and the internal coagulant 6.5 MPa^1/2So that A sponge-like structure was formed in which no finger-like macro voids existed.

The average pore size of the separation layer forming the sponge-like structure may be 0.03 to 0.1 μm. In addition, the separation layer forms a sponge-like structure in which finger-like macro voids do not exist, and forms more uniform pores so that the separation layer has a thickness of 0.03 to 0.1 μm. Pore that satisfies the error range ± 50% of the average pore size can satisfy more than 95% of the total pore. For example, when the average pore size of the sponge-like structure in the PVDF separator is 0.04 μm, it means that pores having a pore diameter of 0.02 to 0.06 μm with an error range of ± 50% satisfy 95% or more of the total pores. .

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples should not be construed as limiting the scope of the present invention, and should be construed to facilitate understanding of the present invention.

≪ Example 1 >

170 parts by weight of solvent dimethylacetamide (DMAc) (solubility: 22.7 MPa ^1/2 ), 30 parts by weight of non-solvent diethylene glycol, and polyethylene glycol with respect to 100 parts by weight of PVDF (Solef 6013, Solvay) having a weight average molecular weight of 440,000 The parts by weight were slowly mixed to prepare a homogeneous polymer solution at 60 ° C.

Bubbles contained in the polymer solution were removed using a vacuum pump, and then transferred to a dual nozzle having an internal diameter of 1.9 mm, an external diameter of 2.5 mm, and maintained at 100 ° C. using a gear pump. Thereafter, the mixture was discharged using a mixed solution (solubility: 29.2 MPa ^1/2 ) mixed with gamma butyrolactone and glycerin in a 6: 4 weight ratio as an internal coagulant, wherein the height of the nozzle and the surface of the coagulation bath (Air gap) was 1 cm. Maintained.

The mixed liquid thus discharged was cooled through a coagulation bath to induce phase separation, and then wound up in a 25 ° C. water bath at a speed of 20 m / min.

50%를 만족하는 0.025 내지 0.075 μm의 기공이 전체 기공의 97 %였다.
The hollow fiber membrane prepared as described above formed a sponge-like structure having an average pore diameter of 0.05 μm, as shown in FIG.

The pores of 0.025 to 0.075 μm satisfying 50% were 97% of the total pores.

≪ Example 2 >

Preparation was carried out in the same manner as in Example 1, except that a mixed solution (solubility: 27.7 MPa ^1/2 ) in which gamma butyrolactone and glycerin were mixed at an 8: 2 weight ratio was used as an internal coagulant.

50%를 만족하는 0.025 내지 0.075 μm의 기공이 전체 기공의 95%였다.
The hollow fiber membrane thus prepared formed a sponge-like structure having an average pore diameter of 0.05 μm, and an error range of average pore diameter of 0.05 μm.

The pores of 0.025 to 0.075 μm satisfying 50% were 95% of the total pores.

≪ Example 3 >

The preparation was carried out in the same manner as in Example 1, except that a mixed solution (solubility: 24.9 MPa ^1/2 ) in which dimethylacetamide and glycerin were mixed at an 8: 2 weight ratio was used as an internal coagulant.

50%를 만족하는 0.03 내지 0.09 μm의 기공이 전체 기공의 98%였다.
The hollow fiber membrane thus prepared formed a sponge-like structure having an average pore size of 0.06 μm, and an error range of average pore size of 0.06 μm.

The pores of 0.03 to 0.09 μm satisfying 50% were 98% of the total pores.

<Example 4>

N-methyl-2-pyrrolidone (solubility: 22.9 MPa ^1/2 ) was used as a solvent, and the mixed solution (solubility: 24.9 MPa ^1/2) which mixed dimethylacetamide and glycerine in a 8: 2 weight ratio as an internal coagulant It was prepared in the same manner as in Example 1 except that was used.

50%를 만족하는 0.035 내지 0.105μm의 기공이 전체 기공의 95%였다.
The hollow fiber membrane thus prepared formed a sponge-like structure with an average pore size of 0.07 μm, and an error range of 0.07 μm with an average pore diameter.

The pores of 0.035 to 0.105 μm satisfying 50% were 95% of the total pores.

&Lt; Example 5 >

It was prepared in the same manner as in Example 1 except that only glycerin (solubility: 33.8 MPa ^1/2 ) was used as the internal coagulant.

50%를 만족하는 0.015 내지 0.045μm의 기공이 전체 기공의 97%였다.
The hollow fiber membrane thus prepared formed a sponge-like structure having an average pore size of 0.03 μm, and an error range of 0.03 μm average pore size.

The pores of 0.015 to 0.045 μm satisfying 50% were 97% of the total pores.

&Lt; Comparative Example 1 &

Dimethylacetamide as solvent use (solubility 22.7 MPa ^1/2), and into the coagulant-dimethylacetamide: Except for using (solubility of 22.7 MPa ^1/2) were prepared by the same manner as in Example 1.

The hollow fiber membrane thus prepared had finger-like pores having a short axis of about 100 μm and a long axis of about 200 μm as shown in FIG. 2.

&Lt; Comparative Example 2 &

Same as Example 1 except that N-methyl-2-pyrrolidone (solubility: 22.9 MPa ^1/2 ) was used as a solvent and dimethylacetamide (solubility: 22.7 MPa ^1/2 ) was used as an internal coagulant. It was prepared by carrying out.

The hollow fiber membrane thus prepared had finger-like pores having a short axis of about 100 μm and a long axis of about 200 μm as shown in FIG. 2.

<Experimental Example>

The net permeability, tensile strength, and rejection rate of the hollow fiber separators prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were measured by the following method, and the results are shown in Table 1.

1. Measurement of pure water permeability

The hollow fiber membrane module was supplied with pure water at a room temperature at a pressure of 1.0 atm on one side of the module by a DEAD-END method, and the amount of permeated water was measured. Then, the unit time, And converted into permeation amount per unit pressure.

2. Measurement of rejection rate

BSA (bovine serum albumin, Aldrich, Mw 66,000) was dissolved in pure water at room temperature to prepare an aqueous solution having a concentration of 1,000 ppm. The aqueous solution was supplied to one side of the prepared hollow fiber membrane module at a pressure of 1.0 kg / cm ² , and the BSA concentration dissolved in the permeated aqueous solution and the raw water initially supplied was measured using an ultraviolet spectrophotometer (Cary-100) Respectively.

Thereafter, the relative ratio of the absorption peaks measured at a wavelength of 278 nm was converted into a percentage using the following equation to determine the BSA elimination rate.

Excretion rate (%) = ((concentration of raw liquid - permeation concentration)) / concentration of raw liquid x 100

3. Measurement of tensile strength

The tensile strength and tensile elongation of the hollow fiber membranes prepared through the tensile tester were measured. The tensile test was carried out at room temperature at a gripping distance of 10 cm and a crosshead speed of 3 cm / min.

(Initial sample length: 100 mm, crosshead speed: 200 mm / min) at a temperature of 23 DEG C and a relative humidity of 50% using a tensile tester ("RTM-100" manufactured by Toyo Baldwin Co., Ltd.).

division Pure permeability
(L / m ² hr) BSA exclusion rate
(%) The tensile strength
(MPa) Example 1 550 99 6 Example 2 600 98 5 Example 3 610 97 5 Example 4 650 95 5 Example 5 400 99 7 Comparative Example 1 780 92 2 Comparative Example 2 750 92 2

50%를 만족하는 기공이 전체 기공의 95%이상을 만족하였다. 방사 원액 내 용매와 내부 응고제를 디메틸아세트아미드로 같은 용액을 사용한 비교예1 또는 다른 용액을 사용하였으나 용해도 파라미터 차가 2 MPa^1/2미만인 비교예2의 경우 핑거 형태(finger-like)기공이 형성되어 인장 강도가 현저히 낮은 것을 확인할 수 있으며, 분리막 파단 발생이 일어났다.  The difference in solubility parameter between solvent and internal coagulant in spinning stock solution is 2 MPa^1/2Satisfying ideal Examples 1 to 5 formed a sponge-like structure, and the error range of the average pore diameter

The pores satisfying 50% satisfied more than 95% of the total pores. Although the solvent and internal coagulant in the spinning stock solution were prepared using Comparative Example 1 or another solution using the same solution as dimethylacetamide, the solubility parameter difference was 2 MPa.^1/2In the case of Comparative Example 2 which is less than, the finger-like pores are formed, it can be confirmed that the tensile strength is significantly low, the occurrence of membrane breakage occurred.

Claims (14)

(1) preparing a spinning stock solution comprising polyvinylidene fluoride (PVDF), a solvent and a nonsolvent; And
(2) spinning the spinning stock solution and the internal coagulant through a spinning nozzle and immersing in the external coagulation liquid to form hollow fiber;
Method for producing a PVDF hollow fiber membrane, characterized in that the difference in the solubility parameter of the solvent in the spinning stock solution and the internal coagulant is 2 ~ 15 MPa ^1/2 . delete The method of claim 1,
The solubility of the solvent in the spinning stock solution is 18 to 35 MPa ^1/2 , the solubility of the internal coagulant is 19 to 50 MPa ^1/2 , the method of producing a PVDF hollow fiber membrane. The method of claim 1,
The solvent is gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide, dibutyl phthalate, dimethyl phthalate (Dimethyl PVDF hollow fiber membrane, characterized in that at least one selected from the group consisting of phthalate, Diethyl phthalate, Dioctyl phthalate, Dioctyl sebacate and Glycerol triacetate Manufacturing method. The method of claim 1,
The non-solvent is a method for producing a PVDF hollow fiber membrane, characterized in that at least one selected from the group consisting of polyethylene glycol, ethylene glycol, propylene glycol, diethylene glycol and propylene glycol methyl ether. The method of claim 1,
The spinning solution is a PVDF hollow fiber membrane manufacturing method characterized in that it comprises 180 to 400 parts by weight of solvent and 30 to 100 parts by weight of non-solvent based on 100 parts by weight of polyvinyl fluoride (PVDF). The method of claim 1,
The internal coagulant is gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide, dibutyl phthalate (Dibutyl Phthalate), dimethyl phthalate ( Dimethyl phthalate, Diethyl phthalate, Dioctyl phthalate, Dioctyl sebacate, Glycerol triacetate, Polyethylene glycol, Ethylene glycol, Propylene glycol, Diethylene glycol, Propylene glycol methyl ether and glycerin (Glycerin) is any one or more selected from the group consisting of PVDF hollow fiber membrane manufacturing method. The method according to claim 1,
The internal coagulant is at least one selected from the group consisting of gamma butyrolactone (γ-butyrolactone), dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP), glycerin (Glycerin), polyethylene glycol ( PEG) and diethylene glycol (DEG) at least any one selected from the group consisting of 5: 5 to 9: 1 by a weight ratio of the manufacturing method of the PVDF hollow fiber membrane.

The method of claim 1,
The solvent is dimethylacetamide (DMAc) or N-methyl-2-pyrrolidone (NMP), and the internal coagulant has a gamma butyrolactone (γ-butyrolactone) and glycerin (Glycerin) of 5: 5 to 9: 1. Method for producing a PVDF hollow fiber membrane, characterized in that the mixed solution mixed in a weight ratio of.

The method of claim 1,
The spinning nozzle of step (2) is a multi-tubular spinning nozzle,
And discharging the spinning stock solution to the outer tube of the multi-tubular spinning nozzle, and simultaneously discharging the internal coagulant to the multi-tubular spinning nozzle inner tube. Hollow; And
And a separation layer formed along the outer periphery of the hollow,
The separation layer includes a sponge like structure, does not include finger-like macro voids, and the average pore size of the separation layer is 0.03 to 0.1 μm, and the average pore size PVDF hollow fiber membrane, characterized in that the pores satisfying the error range ± 50% is 95% or more of the total pores, the water permeability is 500LMH or more. delete delete 12. The method of claim 11,
The hollow fiber membrane PVDF hollow fiber membrane, characterized in that the tensile strength of 5 MPa or more.

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