KR101665189B1 - Polysulfone-based Hollow Fiber Membrane Having Excellent Chemical Resistance and Preparation Method Thereof - Google Patents

Abstract

The present invention relates to a polysulfone-based hollow fiber membrane excellent in chemical resistance and a method for producing the same. In addition to the molecular weight of the pore-forming agent and the molecular weight and content of the polysulfone-based matrix resin, By optimizing the content, it is possible to provide a polysulfone-based hollow fiber membrane excellent in mechanical strength and water permeability as well as excellent in chemical resistance.

Description

TECHNICAL FIELD The present invention relates to a polysulfone-based hollow fiber membrane excellent in chemical resistance and a method for producing the same.

The present invention relates to a polysulfone-based hollow fiber membrane excellent in chemical resistance and a method for producing the same.

Membrane is an obstacle with selective ability existing between two different materials, and is a material that selectively passes or excludes a substance. Basically various polymers can be used as membrane materials, but they are practically limited due to the required physicochemical properties. Accordingly, the film material is selected in consideration of the physical properties required depending on the application such as the manufacturing process, film fouling tendency, chemical durability and thermal stability.

These membrane technologies can be applied to water treatment processes. Membranes used in water treatment process are properties that affect the water treatment ability, and they have mechanical strength and chemical resistance to extend service life; Various water properties such as water permeability associated with the treatment cost are required. Recently, a water treatment method using a fluorine-based polymer material such as polyvinylidene fluoride (PVDF), which has excellent mechanical strength and excellent chemical resistance, has been attracting attention, and accordingly, various PVDF hollow fiber membranes have been developed . As an example thereof, Patent Document 1 discloses a PVDF hollow fiber membrane having a symmetrical structure obtained by hydrophilizing the surface of a hollow fiber membrane extruded using PVDF, an organic solvent and an inorganic fine powder, and Patent Document 2 discloses a cellulose acetate- Discloses a PVDF hollow fiber membrane prepared by spinning a PVDF tank liquid containing a polymer and a PVDF tank liquid containing no hydrophilic polymer through a middle nozzle.

However, the polymer material such as PVDF used in the above techniques has a low water permeability due to its hydrophobic property and is manufactured by the TIPS method, so that the manufacturing process is complicated and the manufacturing cost is high.

The present inventors have found that when the structure of a hollow fiber membrane using a polysulfone-based polymer having a relatively good hydrophilicity is better than that of a fluorine-based resin, the hollow fiber membrane exhibits high water permeability and at the same time, It was confirmed that the chemical resistance was improved, and the present invention was completed.

International Patent Publication No. 2002/070115 WO 2008/001426

The present invention provides a polysulfone-based hollow fiber membrane excellent in mechanical strength and water permeability as well as excellent chemical resistance and a method for producing the same.

In the polysulfone-based hollow fiber membrane according to one embodiment of the present invention,

A hollow structure having an outer surface layer and an inner surface layer,

The ratio of the average diameter of the pores formed in the outer surface layer and the inner surface layer satisfies the following general formula (1)

And satisfies the following general formula (2) concerning chemical resistance.

[Formula 1]

0.1 < Do / Di < 0.9

[Formula 2]

L *? 80

In this formula,

Do represents the average diameter of the pores formed in the outer surface layer,

Di represents an average diameter of pores formed in the inner surface layer,

L * represents the average color coordinate of the hollow fiber membrane at the point of 2 days after immersion in a 50,000 ppm NaOH aqueous solution under KS K 3103 condition.

A method of manufacturing a hollow fiber membrane according to an embodiment of the present invention includes:

A spinning stock solution containing a polysulfone-based matrix resin, and an inner coagulating solution through a nozzle,

The spinning stock solution is characterized by containing 18 to 35 parts by weight of a polysulfone-based matrix resin per 100 parts by weight of the spinning solution.

INDUSTRIAL APPLICABILITY The present invention is not only superior in mechanical strength and water permeability, but also excellent in mechanical strength and water permeability by optimizing the molecular weight of the pore-forming agent and the molecular weight and content of the polysulfone-based matrix resin, A polysulfone-based hollow fiber membrane excellent in chemical properties can be provided.

1 is a schematic view schematically showing a radiation facility according to one embodiment of the present invention.
Figs. 2 to 4 are images showing the results of observing the cross section of the polysulfone-based hollow fiber membrane according to the embodiment or the comparative example by an electron microscope (SEM).
FIG. 5 is an image of the degree of discoloration of the hollow fiber membrane produced in Examples or Comparative Examples at the time of evaluating the chemical resistance under the conditions of KS K 3103. Here, A is the hollow fiber membrane of Example 1, B and C are the hollow fiber membranes of Comparative Example 5, which have been dipped 2 days and 60 days, respectively.
6 is an image showing the result of observation of the cross-section of the hollow fiber membrane produced in Example 1 by an electron microscope (SEM) according to elapsed time when immersed in an aqueous solution of NaOCl at a concentration of 50,000 ppm under KS K 3103.
7 is an image showing the result of observation of the cross-section of the hollow fiber membrane produced in Example 1 by an electron microscope (SEM) according to elapsed time when immersed in an aqueous solution of NaOH at a concentration of 100,000 ppm under KS K 3103.
8 is an image showing the result of SEM observation of the cross-section of the hollow fiber membrane produced in Comparative Example 5 according to elapsed time when immersed in a NaOCl aqueous solution at a concentration of 50,000 ppm under KS K 3103 conditions.
9 is an image showing the result of observation of the cross-section of the hollow fiber membrane produced in Comparative Example 5 by an electron microscope (SEM) according to elapsed time when immersed in an aqueous solution of NaOH at a concentration of 100,000 ppm under KS K 3103.
10 is a graph showing the mechanical strength change rates of the hollow fiber membranes prepared in Examples or Comparative Examples with respect to the elapsed time under the conditions of KS K 3103 under the conditions of KS K 3103: At this time, A was immersed in a NaOCl aqueous solution having a concentration of 50,000 ppm And B is the result of immersing in an aqueous solution of NaOH at a concentration of 100,000 ppm.
11 is a graph showing the rate of change in flow rate of the hollow fiber membrane produced in Examples or Comparative Examples with respect to the elapsed time under the KS K 3103 condition. In this case, A was immersed in a NaOCl aqueous solution having a concentration of 50,000 ppm And B is the result of immersing in an aqueous solution of NaOH at a concentration of 100,000 ppm.

In the present invention, "strength" means a value obtained by dividing a load at a breaking point by an initial unit area, and "water permeability" means a value obtained by measuring the amount of ultrapure water passed through a certain pressure on a unit area.

In the present invention, the term " elongation "refers to the percentage of the elongated length at the time when the fiber is pulled to the original length by pulling it, as a percentage, and can be calculated by the following equation.

Elongation (%) = {Elongated length (cm) / Original length (cm)} × 100

The term "asymmetric structure" in the present invention means an average size variation of pores formed in the direction of the outer surface layer and the inner surface layer, respectively, with reference to a midpoint between an arbitrary point of the inner surface layer of the hollow fiber and the corresponding point of the outer surface layer Which means that the values are different.

In addition, in the present invention, "weight portion" means a weight ratio between the components.

The present invention provides a polysulfone-based hollow fiber membrane excellent in chemical resistance.

As one example, the polysulfone-

A hollow structure having an outer surface layer and an inner surface layer,

The ratio of the average diameter of the pores formed in the outer surface layer and the inner surface layer satisfies the following general formula (1)

Satisfies the following general formula 2 on chemical resistance:

[Formula 1]

0.1 < Do / Di < 0.9

[Formula 2]

L *? 80

In this formula,

Do represents the average diameter of the pores formed in the outer surface layer,

Di represents an average diameter of pores formed in the inner surface layer,

L * represents the average color coordinate of the hollow fiber membrane at the point of 2 days after immersing the hollow fiber membrane in an aqueous solution of NaOH at a concentration of 50 ± 2 ppm at 25 ± 2 ° C under the condition of KS K 3103.

The polysulfone-based hollow fiber membrane according to the present invention is a hollow filter having a hollow ring shape, and has an outer surface layer and an inner surface layer on which pores are formed. Here, the sizes of pores formed in the outer surface layer and the inner surface layer may be different from each other. Specifically, it can have an asymmetric structure in which the pore size increases from the outer surface layer to the inner surface layer. By having such an asymmetric structure of the pores, high mechanical strength and excellent water permeability can be simultaneously realized. At this time, the ratio of the pores formed in the outer and inner surface layers to the average diameter may satisfy the formula (1).

In one embodiment, the sizes of the pores formed in the outer surface layer and the inner surface layer of the polysulfone-based hollow fiber membrane according to the present invention were measured. As a result, it was confirmed that the size of the polysulfone-based hollow fiber membrane was 0.15 to 0.2 μm in the average diameter of the pores formed in the outer surface layer when measured by a 30,000 magnification electron microscope (SEM), and the outer surface layer and the inner surface layer The ratio of the pore diameter to the average diameter satisfied the above general formula (1). From these results, it can be seen that the polysulfone-based hollow fiber membrane improved the mechanical strength and water permeability of the hollow fiber membrane simultaneously by including asymmetric pores in the outer surface layer and the inner surface layer (see Experimental Example 1).

The polysulfone-based hollow fiber membrane is excellent in chemical resistance and satisfies the general formula (1) and the chemical formula (2). Specifically, the hollow fiber membrane preferably satisfies the condition of the general formula 2 at 80 or more; 85 or more; over 90; 91 or more; 92 or higher; 93 or more; 94 or higher; Or 95 or more.

In one embodiment, the color difference yellowness index of the hollow fiber membrane according to the chemical treatment of KS K 3103 condition was evaluated for the polysulfone hollow fiber membrane according to the present invention. As a result, it was confirmed that the polysulfone-based hollow fiber membrane showed a low b * value indicating the ratio of yellow to blue after the chemical treatment and a high brightness (L *) of 80 or more. From these results, it can be seen that the polysulfone-based hollow fiber membrane according to the present invention has excellent chemical resistance and satisfies the formula 2 (see Experimental Example 2).

As another example, the polysulfone-based hollow fiber membrane satisfies the following general formula 3 regarding chemical resistance:

[Formula 3]

| (S _r1 -S _r2 ) / S _r1 X 100 | ≤ 3

In this formula,

S _r1 represents elongation before immersing the hollow fiber membrane in an aqueous solution of NaOCl at a concentration of 50,000 ppm at 25 ± 2 ° C,

delete

delete

S _r2 represents the elongation at 60 days after immersion of the hollow fiber membrane in aqueous solution of NaOCl at a concentration of 50 ± 2 ppm at 25 ± 2 ° C under the conditions of KS K 3103.

In one embodiment, the polysulfone-based hollow fiber membrane according to the present invention was evaluated for the degree of pore formation and degree of elongation formed on the inner and outer surface layers by chemical treatment under the conditions of KS K 3103. As a result, as shown in FIG. 6 and FIG. 7, the polysulfone-based hollow fiber membrane was maintained in a state where the size and shape of the pores formed on the inner and outer surface layers of the hollow fiber membrane were kept constant before and after immersion in NaOH solution or NaOCl solution . In addition, the elongation of the hollow fiber membrane after the chemical treatment was found to satisfy the above-mentioned general formula 3 with a reduction rate of 1% or less based on the elongation before the chemical treatment. From these results, it can be seen that the polysulfone-based hollow fiber membrane according to the present invention has improved chemical resistance, so that the size and shape deformation due to the chemical treatment of the pores formed on the inner and outer surface layers are suppressed, (See Experimental Example 3). &Lt; tb &gt;&lt; TABLE &gt;

As another example, the polysulfone-based hollow fiber membrane may satisfy the following chemical formula 4 for chemical resistance:

[Formula 4]

(S _t1 -S _t2 ) / S _t1 X 100? 10

In this formula,

S _t1 represents the strength of the hollow fiber membrane before immersing it in an aqueous solution of NaOH at a concentration of 25 ± 2 ° C and 100,000 ppm,

S _t2 represents the strength of the hollow fiber membrane after 60 days of immersion in an aqueous solution of NaOH at a concentration of 25 ± 2 ° C and 100,000 ppm under the conditions of KS K 3103.

In one embodiment, the polysulfone hollow fiber membrane according to the present invention was evaluated for the degree of change in the shape and mechanical strength of the pores formed on the inner and outer surface layers according to the chemical treatment of KS K 3103 conditions. As a result, as shown in FIG. 6 and FIG. 7, the polysulfone-based hollow fiber membrane was found to have a constant size and shape of pores formed in the inner and outer surface layers of the hollow fiber membrane before and after treatment with NaOH solution or NaOCl solution I could confirm. Further, the mechanical strength of the hollow fiber membrane after the chemical treatment was found to satisfy the above-mentioned formula 4 because it had a reduction rate of 4 to 8% based on the mechanical strength before the chemical treatment. From these results, it can be seen that the polysulfone-based hollow fiber membrane according to the present invention has improved chemical resistance, so that the size and shape deformation due to the chemical treatment of the pores formed on the inner and outer surface layers are suppressed, (See Experimental Example 3). &Lt; tb &gt; &lt; TABLE &gt;

At this time, the strength of the polysulfone-based hollow fiber membrane may be 6.5 Mpa or more. Specifically, the strength may be in the range of 6.5 Mpa or more, 7 Mpa or more, 7 to 20 Mpa, or 7 to 9 Mpa.

As another example, the polysulfone-based hollow fiber membrane may satisfy the following chemical formula 5 for chemical resistance:

[Formula 5]

(F ₁ -F ₂ ) / F ₁ X 100 ≤ 15

In this formula,

F ₁ represents the flow rate before immersing the hollow fiber membrane in an aqueous solution of NaOH at a concentration of 100,000 ppm at 25 ± 2 ° C,

F ₂ represents the flow rate at 60 days after immersion of the hollow fiber membrane in an aqueous solution of NaOH at a concentration of 25 ± 2 ° C and 100,000 ppm under the conditions of KS K 3103.

In one embodiment, the polysulfone-based hollow fiber membrane according to the present invention was evaluated for the degree of pore shape and flow rate change in the inner and outer surface layers according to the chemical treatment of KS K 3103 condition. As a result, as shown in FIG. 6 and FIG. 7, the polysulfone-based hollow fiber membrane was found to have a constant size and shape of pores formed in the inner and outer surface layers of the hollow fiber membrane before and after treatment with NaOH solution or NaOCl solution I could confirm. In addition, the flow rate of the hollow fiber membrane after the chemical treatment has a reduction rate of 7 to 10% based on the flow rate prior to the chemical treatment, so that it satisfies the general formula (5). From these results, it can be seen that the polysulfone-based hollow fiber membrane according to the present invention has improved chemical resistance, so that the size and shape deformation due to the chemical treatment of the pores formed on the inner and outer surface layers are suppressed, (See Experimental Example 3). &Lt; tb &gt; &lt; TABLE &gt;

At this time, the polysulfone-based hollow fiber membrane may have a water permeability of 1000 to 5000 LMH for ultrapure water. Specifically, the water permeability is 1500 to 2500 LMH; 950 to 3500 LMH; 950 to 4000 LMH; 1000 to 3500 LMH; 1500 to 4000 LMH; 2500 to 4000 LMH; 950 to 2500 LMH; 2500 to 4000 LMH; 1750 to 4750 LMH; 3500 to 4750 LMH; Or 2500 to 4500 LMH.

Further, the polysulfone-based hollow fiber membrane according to the present invention includes a polysulfone resin, and the polysulfone resin is not particularly limited as long as it can form a hollow fiber membrane. As one example, the polysulfone-based matrix resin may be polysulfone, polyethersulfone, or a mixture thereof as a base resin.

The polysulfone-based hollow fiber membrane according to the present invention is excellent in mechanical strength and water permeability, and is excellent in chemical resistance. Therefore, it can be suitably used for microfiltration, ultrafiltration or nanofiltration water treatment, and can be used for water purification, Industrial water treatment, domestic water treatment, and the like.

The present invention also provides a method for producing the polysulfone-based hollow fiber membrane as described above.

As one example, a method for producing a polysulfone-based hollow fiber membrane according to the present invention comprises spinning a spinning stock solution containing a polysulfone-based matrix resin and an inner coagulation solution through a nozzle, And 18 to 35 parts by weight of a polysulfone-based matrix resin per 100 parts by weight of the spinning solution. Specifically, the spinning stock solution contains 18 to 35 parts by weight of a polysulfone-based matrix resin; 18 to 28 parts by weight; 25 to 35 parts by weight; 28 to 32 parts by weight; 19 to 25 parts by weight; 20 to 27 parts by weight; Or 19 to 22 parts by weight.

The method for producing a polysulfone-based hollow fiber membrane according to the present invention is characterized in that the content of the polysulfone resin as the matrix resin in the spinning stock solution is such that the ratio of the pores formed in the outer surface layer and the inner surface layer, The hollow fiber membrane having the hollow structure satisfying the following formula 2 can be prepared, thereby improving the chemical resistance of the hollow fiber membrane and satisfying the following general formula 2:

[Formula 1]

0.1 < Do / Di < 0.9

[Formula 2]

L *? 80

In this formula,

Do represents the average diameter of the pores formed in the outer surface layer,

Di represents an average diameter of pores formed in the inner surface layer,

L * represents the average color coordinate of the hollow fiber membrane at the point of 2 days after immersing the hollow fiber membrane in an aqueous solution of NaOH at a concentration of 50 ± 2 ppm at 25 ± 2 ° C under the condition of KS K 3103.

Specifically, the formula 2 is preferably 80 or more; 85 or more; over 90; 91 or more; 92 or higher; 93 or more; 94 or higher; Or 95 or more.

As another example, the spinning solution may be a polysulfone-based matrix resin; A crosslinking resin; Pore formers; And a non-solvent, and the weight average molecular weight of the pore-forming agent may be 800 or less. As one example, the weight average molecular weight of the pore-former may range from 100 to 800, 150 to 650, 150 to 450, 350 to 650, or 200 to 600. [

In the process of preparing the polysulfone-based hollow fiber membrane according to the present invention, the pore-forming agent is poured into the coagulating solution and forms a pore while converting into a non-solvent. If the weight average molecular weight of the pore-forming agent is excessively large, the phase change speed is slowed, and the pore size formed thereby becomes large. For example, when a pore-forming agent having a large weight average molecular weight is used in the production of a hollow fiber membrane, a polysulfone-based hollow fiber membrane having a pore structure of a finger structure can be produced.

At this time, the polysulfone-based matrix resin is not particularly limited as long as it can form a hollow fiber membrane. As one example, the polysulfone-based matrix resin may be polysulfone, polyethersulfone, or a mixture thereof as a base resin. Polysulfone resins are excellent in heat resistance, have a wide pH range to be applied, and are excellent in solubility in solvents, thus facilitating conditioning of a spinning dope.

The crosslinking resin is not particularly limited as long as it can form a crosslink in the polysulfone-based matrix resin. The crosslinking resin induces crosslinking of the polysulfone-based hollow fiber membrane, affects hydrophilicity imparting, and is closely related to water permeability. For example, the crosslinking resin provides cross-linkage of the hydrophilic group inside the polysulfone resin to increase the hydrophilicity of the polysulfone-based hollow fiber. Examples of the crosslinking resin include polyvinylpyrrolidone (PVP), cellulose acetate (CA), polyacrylamide (PAAm), and polyvinyl alcohol (PVA) And at least one selected from the group consisting of

Further, the pore-forming agent is not particularly limited as long as it forms pores through phase conversion with non-solvent. Pore-forming agents affect pore formation of polysulfone-based hollow fiber membranes and are closely related to water permeability. As one example, the pore forming agent present in the spinning stock solution can absorb the non-solvent of the coagulating solution while the spinning spinning solution is discharged from the double pipe type nozzle and stays in the coagulation bath, so that the spinning stock solution can be easily converted into the solvent. In addition, the pore-forming agent serves as a swelling agent and provides an effect of increasing the pore size. The type of porogen is selected from the group consisting of, for example, polyethylene glycol, polypropylene glycol, ethylene glycol, glycerin and castor oil It may be more than one kind.

The type of the solvent is not particularly limited and includes, for example, dimethylacetamide (DMAc), dimethylformamide (DMF), chloroform, N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone, NMP), and dimethylsulfoxide (DMSO). For example, dimethylacetamide (DMAc) may be used as the solvent.

In addition, the type of the non-solvent is not particularly limited, and water, an alcohol, or a mixture thereof may be used. For example, ultrapure water or methanol may be used as the non-solvent.

As another example, the spinning stock solution may satisfy the following general formula 6 or 7, and in some cases, it may satisfy the general formulas 6 and 7 simultaneously.

[Formula 6]

90 < MWm / MWp < 500,

[Formula 7]

20 <MWc / MWp <300

In this formula,

MWm represents the weight average molecular weight of the polysulfone-based matrix resin,

MWp represents the weight average molecular weight of the pore-forming agent,

MWc represents the weight average molecular weight of the crosslinking resin.

The inventors of the present invention have conducted repeated and various experiments to control the weight average molecular weight of the polysulfone-based matrix resin, the pore-forming agent and the crosslinking-forming resin to satisfy the above-mentioned general formulas 6 and / It is possible to improve the chemical resistance of the composition. As one example, the weight average molecular weight of the polysulfone-based matrix resin may range from 65,000 to 80,000, and the weight average molecular weight of the crosslinking resin may range from 25,000 to 35,000. In this case, the pore-forming agent has a weight average molecular weight of 800 or less, for example, in the range of 200 to 600. [

In addition, the above-

18 to 35 parts by weight of a matrix resin;

10 to 30 parts by weight of a pore-forming agent;

2 to 10 parts by weight of a crosslinking resin;

45 to 55 parts by weight of a solvent; And

And 2 to 10 parts by weight of the non-solvent.

Specifically, the spinning stock solution comprises 18 to 25 parts by weight of a polysulfone-based matrix resin; 3 to 7 parts by weight of a crosslinking resin; 15 to 25 parts by weight of a pore-forming agent; 45 to 55 parts by weight of a solvent; And 3 to 8 parts by weight of non-solvent can be manufactured by way of example, and the scope of the present invention is not limited thereto.

The above composition ranges are derived from the range in which the inventors of the present invention can repeatedly and experimentally control the viscosity of the composition and improve the chemical resistance of the produced hollow fiber.

As one example, the content ratio of the polysulfone-based matrix resin and the non-solvent contained in the spinning solution may satisfy the following general formula (8)

[Formula 8]

1 < Wm / Wns < 20

In this formula,

Wm represents the content (parts by weight) of the matrix resin,

And Wns represents the content (parts by weight) of the non-solvent.

By controlling the content of the polysulfone-based matrix resin and the non-solvent content within the above range, the spinning stock solution can appropriately control the viscosity of the spinning solution during the production of the hollow fiber, and in particular, the problem that the water permeability is lowered can be prevented .

The spinning viscosity of the spinning solution may range from 20,000 to 24,500 cps. Specifically, the viscosity may range from 20,000 to 24,000 cps, 21,000 to 24,500 cps, 21,000 to 24,000 cps, 21,000 to 23,000 cps, 22,000 to 24,000 cps, or 22,000 to 23,000 cps. By controlling the spinning viscosity of the spinning stock solution in the above range, the pore size and pore distribution can be controlled appropriately and excellent water permeability can be realized.

Furthermore, the internal coagulating solution may be prepared by adding 10 to 30 parts by weight of non-solvent; And 70 to 90 parts by weight of a solvent.

As one example, the method for producing the polysulfone-

A spinning step of spinning the spinning stock solution and the inner coagulating solution through the double nozzle;

A phase change step in which the spinning liquid and the inner coagulating liquid radiated from the nozzle undergo crystallization of the resin through the air gap and phase transformation with water vapor; And

The solvent and the pore forming agent may include a pore forming step of forming a pore by performing a phase transfer with the non-solvent.

As another example, in the spinning process, the spinning temperature of the spinning solution may be 20 to 35 占 폚, and the spinning temperature of the inner coagulating solution may be in the range of 40 to 60 占 폚. In the present invention, the size and distribution of pores can be appropriately controlled by controlling the temperature of the spinning stock solution and the inner coagulating solution. That is, by applying the hybrid phase separation method in which the solvent-induced phase separation method and the heat-induced phase separation method can be simultaneously carried out at the time of phase change, the mechanical strength of the polysulfone type hollow fiber membrane can be improved and the asymmetric structure of the pores Can be implemented.

A schematic representation of the spinning process of the present invention is shown in Fig. 1 as an example. 1, the spinning apparatus used in the spinning step of the spinning stock solution and the inner coagulating solution is composed of a spinning dope tank 11 and an inner coagulating liquid tank 12, a gear pump 21, An air gap 40, a coagulation tank 50, a water treatment tank 60, an elongating tank 70, and a take-up tank 80 in which a pump 22 is interlocked.

In the process line of the spinning liquid Dope and the inner core liquid tank 11 and 12 and the nozzle 30, a fruiting system can be constructed to maintain the temperature in the range of 25 to 200 ° C.

The nozzle 30 can be vertically and horizontally moved in the mount to adjust the air gap 40 between the nozzle 30 and the coagulation bath 50. The air gap 40 is a section in which the first-order phase change occurs, and the water in the air and the organic solvent in the spinning liquid are exchanged for phase change.

The coagulation tank 50 is provided with a multi-stage godet roller in the coagulation tank 50 to extend the residence time of the separation membrane in order to extend the phase change time to the place where the secondary phase change occurs. Also, by providing a multi-stage godet roller in the water tank 60, the residence time can be adjusted.

The retention stage of the water treatment tank (60) is a stage where the phase of the spinning stock solution, in which the phase change in the coagulation tank (50) is not completed, is converted into a tertiary phase and washing of the inner coagulating solution is performed.

The longer the total residence time, the more advantageous for phase change and cleaning, but the longer the production process time and the lower the productivity, so it is desirable to select the optimum condition at an appropriate level.

As the specific spinning process conditions, the hollow fiber is discharged by spinning the prepared spinning stock solution and the inner coagulating solution using the double pipe type nozzle 30, and the first phase is changed in the air gap (40, air gap). And then passes through the coagulation bath (50) to perform the second phase conversion. Thereafter, the additive and the residual organic solvent are removed from the water bath 60, and the water is transferred to the winding drum 80 and wound, thereby completing the spinning process.

Further, the present invention provides a water treatment module including the above-described hollow fiber membrane.

As one example, a water treatment module according to the present invention comprises:

A hollow fiber membrane module including a plurality of hollow fiber membranes and a potting portion for fixing one or both ends of the hollow fiber membranes;

A hollow housing into which the hollow fiber membrane module is inserted; And

And a housing cap which is located at one or both ends of the hollow housing and has a pipe connecting portion to which the fluid connecting pipe is connected.

The fluid connection pipe is not particularly limited and may include, for example, at least one of a water supply target water supply line, an air injection line, a purified water discharge line, and a concentrated water discharge line.

Hereinafter, the present invention will be described in detail by way of Examples and the like according to the present invention, but the scope of the present invention is not limited thereto.

Example  1 and 2.

First, a spinning stock solution containing a polysulfone-based matrix resin and an inner coagulating solution were prepared by the compositions shown in Table 1 below. At this time, the contents of PES, PVP, PEG, Nonspecific and DMAc in Table 1 are shown in terms of parts by weight.

ingredient Example 1 Example 2 Spinning liquid Polyisocyanurate (PES) 20 22 Polyvinylpyrrolidone (PVP) 5 5 Polyethylene glycol (PEG) 19 19 Expense 6 (water) 6 (water) Dimethylacetamide (DMAc) 50 48 Viscosity (cps) 22,000 23,500 Internal coagulation amount DMAc / water content (parts by weight) 80/20 80/20

As shown in Table 1, it was confirmed that the prepared spinning solution maintained a viscosity ranging from 22,000 to 23,500 cps. Thereafter, the prepared spinning solution and inner coagulating solution were spinned with a double nozzle under the following spinning conditions to prepare a polysulfone-based hollow fiber membrane.

· Spinning temperature of spinning liquid: 25 ℃

· Radiation temperature of internal coagulating liquid: 50 ℃

· Temperature of coagulation bath: 50 ℃

· Coagulation time: 5 minutes

· Radial speed: 20 m / min

Comparative Example  1 to 5.

A spinning stock solution and an inner coagulating solution were prepared by the compositions shown in Table 2 below. In this case, the contents of PES, PVP, PEG, Nonaqueous solution and DMAc in Table 2 are expressed in terms of parts by weight.

ingredient Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Spinning liquid Polyisocyanurate (PES) 20 15 10 20 - Polyvinylidene fluoride (PVDF) - - - - 20 Polyvinylpyrrolidone (PVP) 5 5 5 7 5 Polyethylene glycol (PEG) 19 19 19 20 19 Expense 6 (water) 6 (water) 6 (water) - 6 (water) Dimethylacetamide (DMAc) 50 55 60 53 50 Viscosity (cps) 28,000 16,800 15,400 19,000 24,000 Internal coagulation amount DMAc / water content (parts by weight) 80/20 80/20 80/20 80/20 80/20

The spinning solution and inner coagulating solution prepared in the composition shown in Table 2 were spinned with a double nozzle under the following spinning conditions to prepare a hollow fiber membrane.

· Spinning temperature of spinning liquid: 25 ℃

· Radiation temperature of internal coagulating liquid: 50 ℃

· Temperature of coagulation bath: 50 ℃

· Coagulation time: 5 minutes

· Radial speed: 20 m / min

Experimental Example  1. Electron microscope ( SEM ) observe

Sections of the polysulfone-based hollow fiber membranes prepared in Example 1 and Comparative Examples 1 and 4 were observed with an electron microscope (SEM). At this time, the magnification (SEM) of the electron microscope was 30,000 magnifications, and the observed results are shown in FIGS. 2 to 4, respectively.

FIG. 2 shows the polysulfone-based hollow fiber membrane according to Example 1, wherein the polysulfone-based hollow fiber membrane has an asymmetric porous structure in which the pore size is continuously increased from the outer surface layer to the inner surface layer. It was also confirmed that the average diameter of the pores formed in the outer surface layer was 0.15 to 0.2 μm.

FIG. 3 shows the result of observing the polysulfone hollow fiber membrane according to Comparative Example 1 using a spinning stock solution having a high viscosity. As a result, it can be confirmed that the hollow fiber membrane according to Comparative Example 1 has macropores of a finger structure formed on its cross section.

4 shows the results of observing the polysulfone-based hollow fiber membrane according to Comparative Example 4 in which the non-solvent was not used, and it was confirmed that the hollow fiber membrane according to Comparative Example 4 had irregular macropores on its cross section.

From these results, it can be seen that the polysulfone-based hollow fiber membrane according to the present invention has a viscosity of 20,000 to 24,500 cps when producing the hollow fiber membrane, and the pore size is continuously increased from the outer surface layer to the inner surface layer by using the spinning stock solution containing non- It is possible to produce a polysulfone-based hollow fiber membrane having an asymmetric porous structure.

Experimental Example  2. Changes in Properties of Hollow Fiber Membranes by Chemical Treatment 1

For the hollow fiber membranes prepared in Example 1 and Comparative Example 5, the color change after the chemical treatment was visually confirmed, and the results are shown in FIG.

In addition, the color difference yellowness index of the hollow fiber membranes before and after the chemical treatment was evaluated. The chemical treatment of the hollow fiber membranes was performed for 60 days according to the conditions of KS K 3103 by preparing an aqueous NaOH solution having a concentration of 50,000 ppm and the color difference yellowing degree of each hollow fiber membrane was measured before immersion, The chromaticity coordinates of the hollow fiber membrane were measured at the elapsed time. Hereinafter, a method of measuring the color coordinates will be briefly described.

Color Coordinates: L , a, and b of CIE color coordinates showing three-dimensional values of lightness and chroma were measured at arbitrary three points on the hollow fiber membrane of 3 cm x 3 cm in length. At this time, the measurement was performed using a color matching tester (Gretag Macbeth 7000A) in an atmosphere of an ambient temperature of 25 ± 2 ° C. and a relative humidity of 50%. The color models were L (lightness), a and b Red / green, yellow / blue complementary axis). Table 3 shows the brightness (L *) values of the average values of the measured color coordinates that are found to have the greatest deviation.

Immersion time Brightness deviation 0 hours 2 days Example 1 97.253 96.537 0.716 Comparative Example 5 94.482 75.891 18.591

5, in the polysulfone-based hollow fiber membrane of Example 1, the hue after 2 days of immersion of the aqueous NaOH solution was not so large as that before the immersion, and it was difficult to confirm whether the hue was discolored visually. However, in the case of the hollow fiber membrane of Comparative Example 5, it was found to be yellow ocher after 2 days of dipping of aqueous NaOH solution, and discolored to brown after 60 days.

As a result of the measurement of chromaticity coordinates of the hollow fiber membranes of Example 1 and Comparative Example 5, the chromaticity coordinate deviations of b * before and after immersion in aqueous NaOH solution were not large. However, after 2 days of immersion, The hollow fiber membranes had b * values of 2.222 and 7.766, respectively, and the hollow fiber membranes of Comparative Example 5 had a color difference yellowing degree of 3 times or more as compared with the hollow fiber membranes of Example 1. As shown in Table 3, the lightness (L *) having the greatest value among the color coordinate deviations was 0.716 and 18.591, respectively, for the hollow fiber membranes of Examples 1 and 5. In other words, the polysulfone-based hollow fiber membrane of Example 1 maintained a lightness (L *) of about 95 or more regardless of chemical treatment, whereas the fluorinated hollow fiber membrane of Comparative Example 5 had a lightness (L *) of about 15 Or more.

From these results, it can be seen that the polysulfone-based hollow fiber membrane according to the present invention is remarkably improved in chemical resistance by controlling the molecular weight and content of the polysulfone-based matrix resin in the production of the hollow fiber membrane and the content of non- .

Experimental Example  3. Changes in Properties of Hollow Fiber Membranes by Chemical Treatment 2

Initial strength, elongation and flow rate of the hollow fiber membranes prepared in Examples 1, 2 and Comparative Examples 2 to 5 before and after the chemical treatment were measured.

At this time, NaOCl aqueous solution having a concentration of 50,000 ppm and NaOH aqueous solution having a concentration of 100,000 ppm were prepared by chemical treatment of the hollow fiber membrane, and the aqueous solution was used for 120 days according to the conditions of KS K 3103 . The strength, elongation and flow rate of each hollow fiber membrane were measured at 30 days and 60 days after immersion. In addition, at 1, 30, 90, and 120 days after soaking, the sections of the immersed hollow fiber membranes were observed under an electron microscope (SEM). Hereinafter, methods of measuring strength, elongation and flow rate will be briefly described.

Strength and elongation: The tensile strength was measured under the conditions of an initial sample length of 100 mm (ie, gripping distance) and a crosshead speed of 200 mm / min, using an Instron 5564 instrument at a temperature of 25 ± 2 ° C. and a relative humidity of 50% Respectively. The curve Grip is used to minimize damage to the point being struck, and the error range of the measured value is ± 2%.

Strength = load at break point / initial unit area

Elongation (%) = {Elongated length (cm) / Original length (cm)} × 100

Flow rate: The amount of ultrapure water passed through the unit area was measured by applying a constant pressure. At this time, the ultrapure water was maintained at 25 캜 and measured under an atmosphere of an environmental temperature of 25 2 캜 and a relative humidity of 50%.

From the results measured by the above method, the reduction rates of the strength, elongation and flow rate at the elapse of 60 days of chemical treatment based on the measured value (100%) measured before the chemical treatment were deduced. Table 5 shows the results. Table 4 shows the results of hollow fiber membranes treated with a NaOCl aqueous solution having a concentration of 50,000 ppm, and Table 5 shows hollow fiber membranes treated with a NaOH aqueous solution having a concentration of 100,000 ppm. 6 and 7 show the hollow fiber membrane cross-section of Example 1 observed with an electron microscope (SEM), and FIGS. 8 and 9 show the hollow fiber membrane cross-section of Comparative Example 5.

Strength reduction rate (%) Elongation reduction rate (%) Flow rate reduction (%) Example 1 8 One 10 Example 2 5 One 8 Comparative Example 2 20 5 18 Comparative Example 3 50 20 30 Comparative Example 4 15 5 20 Comparative Example 5 12 5 17

Strength reduction rate (%) Elongation reduction rate (%) Flow rate reduction (%) Example 1 6 One 10 Example 2 4 One 7 Comparative Example 2 15 4 17 Comparative Example 3 35 15 25 Comparative Example 4 14 7 17 Comparative Example 5 10 6 15

Referring to the results of Tables 4 and 5, regarding the mechanical strength of the hollow fiber membrane, the polysulfone hollow fiber membranes of Examples 1 and 2 had a mechanical strength reduction rate of 4 to 8% due to the treatment of NaOH aqueous solution or NaOCl aqueous solution appear. On the other hand, the hollow fiber membranes of Comparative Examples 2 and 3 in which the content of the polysulfone-based matrix resin was low showed that the mechanical strength was remarkably decreased as the polysulfone resin content was decreased. In addition, the hollow fiber membrane of Comparative Example 4 using the spinning solution containing no nonsolvent had a reduction ratio of about 1.88 to 3 times higher than that of the hollow fiber membrane of Example, and the hollow fiber membrane of Comparative Example 5 using the fluororesin as the matrix resin Desertification showed a 12% decrease in the mechanical strength and a high reduction rate compared with the polysulfone-based hollow fiber membrane according to the present invention.

In addition, the polysulfone-based hollow fiber membranes of Examples 1 and 2 were shown to have an elongation reduction of 1% or less, while the hollow fiber membranes of Comparative Examples 2 to 5 had a high elongation reduction rate of 4 to 20%. In particular, in the case of the hollow fiber membrane produced in Comparative Example 3 in which the content of the polysulfone-based matrix resin was remarkably small, the elongation reduction rate was 15 to 20%, which was found to be very large.

Further, with respect to the flow rate, the polysulfone-based hollow fiber membranes of Examples 1 and 2 exhibited a low flow rate reduction of 7 to 10%. On the contrary, the hollow fiber membranes of Comparative Examples 2 to 5 exhibited a flow rate reduction rate of 15 to 30%, indicating that the reduction rate due to the chemical treatment was very large.

6 and 7, in the case of the polysulfone-based hollow fiber membrane of Example 1, the size and shape of the pores formed in the outer surface layer and the inner surface layer were kept constant even after 4 months of immersion in the NaOH aqueous solution or NaOCl aqueous solution Respectively.

However, referring to FIGS. 8 and 9, the hollow fiber membrane of Comparative Example 5 starts to change in size and shape of the pores formed in the outer surface layer at a point of time when one day of immersion has elapsed. Was deformed into macropores of a finger structure, and pores formed in the inner surface layer were found to vary in size unevenly.

From these results, it can be seen that the polysulfone-based hollow fiber membrane according to the present invention significantly improves the chemical resistance by controlling the molecular weight and the content of the polysulfone-based matrix resin in the production of the hollow fiber membrane, It is possible to suppress the deformation of the pores formed in the inner and outer surface layers due to the treatment, and as a result, it is possible to prevent the durability of the hollow fiber membrane due to the chemical treatment and deterioration of the water permeability.

11: spinning stock tank 12: internal coagulating solution tank
21: gear pump 22: metering pump
30: double pipe type nozzle 40: air gap
50: coagulation bath 60: water bath
70: drawing machine 80: winding machine

Claims (9)

A hollow structure having an outer surface layer and an inner surface layer,
The average diameter of the pores formed in the outer surface layer is 0.15 to 0.2 탆,
The ratio of the average diameter of the pores formed in the outer surface layer and the inner surface layer satisfies the following general formula (1)
Polysulfone-based hollow fiber membranes satisfying the following general formulas 2 to 5 regarding chemical resistance:
[Formula 1]
0.1 < Do / Di < 0.9
[Formula 2]
L *? 80
[Formula 3]
| (S _r1 -S _r2 ) / S _r1 X 100 | ≤ 3
[Formula 4]
(S _t1 -S _t2 ) / S _t1 X 100? 10
[Formula 5]
(F ₁ -F ₂ ) / F ₁ X 100 ≤ 15
In this formula,
Do represents the average diameter of the pores formed in the outer surface layer,
Di represents an average diameter of pores formed in the inner surface layer,
L * represents the lightness of the average color coordinates at the point of 2 days after the immersion of the hollow fiber membrane in an NaOH aqueous solution of 25 ± 2 ° C. and a concentration of 50,000 ppm under the conditions of KS K 3103,
S _r1 represents the elongation before immersing the hollow fiber membrane in an aqueous solution of NaOCl at a concentration of 50 ± 2 ppm at 25 ± 2 ° C.,
S _r2 represents the elongation at 60 days after the immersion of the hollow fiber membrane in an aqueous solution of NaOCl at a concentration of 50 ± 2 ppm at 25 ± 2 ° C under the conditions of KS K 3103,
S _t1 represents the strength of the hollow fiber membrane before immersing it in an aqueous solution of NaOH at a concentration of 25 ± 2 ° C and a concentration of 100,000 ppm,
S _t2 represents the strength of the hollow fiber membrane after 60 days of immersion in an aqueous solution of NaOH at a concentration of 25 ± 2 ° C. and 100,000 ppm under the conditions of KS K 3103,
F ₁ represents the flow rate before immersing the hollow fiber membrane in an aqueous solution of NaOH having a concentration of 100,000 ppm at 25 ± 2 ° C,
F ₂ represents the flow rate at 60 days after the immersion of the hollow fiber membrane in an aqueous solution of NaOH at a concentration of 25 ± 2 ° C and 100,000 ppm under the conditions of KS K 3103.
delete delete delete delete The method according to claim 1,
The polysulfone-based hollow fiber membrane includes at least one selected from the group consisting of polysulfone and polyethersulfone.
A spinning stock solution containing a polysulfone-based matrix resin, and an inner coagulating solution through a nozzle,
Wherein the spinning stock solution comprises 18 to 35 parts by weight of a polysulfone-based matrix resin per 100 parts by weight of the spinning solution,
Wherein the viscosity of the spinning solution is 20,000 to 24,500 cps.
8. The method of claim 7,
The spinning liquid may be a polysulfone-based matrix resin; A crosslinking resin; Pore formers; And non-payment,
The weight average molecular weight of the pore-forming agent is 800 or less,
A process for producing a polysulfone-based hollow fiber membrane satisfying the following general formula 6 or 7:
[Formula 6]
90 <MWm / MWp <500
[Formula 7]
20 <MWc / MWp <300
In this formula,
MWm represents the weight average molecular weight of the polysulfone-based matrix resin,
MWp represents the weight average molecular weight of the pore-forming agent,
MWc represents the weight average molecular weight of the crosslinking resin.
8. The method of claim 7,
A method for producing a polysulfone-based hollow fiber membrane comprises:
A spinning step of spinning a spinning stock solution containing a polysulfone type matrix resin and an inner coagulating solution through a double nozzle;
A phase change step in which the spinning liquid and the inner coagulating liquid radiated from the nozzle undergo crystallization of the resin through the air gap and phase transformation with water vapor; And
Wherein the solvent contained in the spinning solution and the pore-forming agent are phase-converted with the non-solvent contained in the inner coagulating solution to form pores.

Images