KR20010028009A - A hydrophillic polysulfone based hollow fiber membrane and process for preparing the same - Google Patents

Abstract

PURPOSE: Disclosed are a hollow filter membrane of poly-sulfone group and a preparation method thereof. The membrane is composed of 1 - 50 wt% of water-soluble compounds and 0.01 - 10 wt% of water-soluble metal salts. CONSTITUTION: The preparation method of a sulfone group hollow filter membrane follows the next procedure: a sulfone group polymer is dissolved in the organic solvent and prepares a thread dope by addition of 10,000 molecular weight of vinylpyrrolidone polymer or polyglycol of polyethylene-glycol or polyvinyl-alcohol. The organic solvent may be used as m-cresol, chlorobenzene, N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl acetamide or dimethyl formamide. The content of polysulfone polymer structured in a thread dope is 10 - 25 wt% and the total content of vinylpyrrolidone and polyglycol is also 10 - 25wt%. The prepared dope is again threaded with the dual tubular nozzle of inner coagulating solution such as diethylene-glycol compounds in the atmosphere. In addition, outer coagulating solution may be used as water. The membrane is dipped in a water-soluble solution and dried to prepare the final hollow filter membrane.

Description

A hydrophillic polysulfone based hollow fiber membrane and process for preparing the same

The present invention relates to a polysulfone hollow fiber membrane and a method for manufacturing the same, and more particularly, to a hydrophilized polysulfone hollow fiber membrane having excellent permeability by attaching a hydrophilic material evenly to the surface of the membrane and a method for manufacturing the same.

Membrane technology has been developed variously with great attention in terms of energy saving and compactness of the system. As a material of the selective permeable membrane used in such a system, many kinds of polymers have been researched and developed, for example, cellulose, polyamide, polyacrylonitrile, polycarbonate, polyphenylene oxide, and polysulfone. Polymers, such as a phone type, are mentioned.

Hydrophobic polymers, such as polysulfone, polycarbonate, and polyphenylene oxide, were originally used as engineering plastics, but have been selected and used as materials for separation membranes because of their excellent heat resistance and mechanical properties. However, such hydrophobic polymers are very hydrophobic compared to hydrophilic resins such as cellulose acetate and the like, and especially when formed into a dry separator, they are remarkably water-repellent and do not exhibit sufficient permeability because the membrane becomes incompatible with water. There is a case.

Therefore, the separator formed of a hydrophobic resin such as polysulfone cannot be used for industrial and medical equipment which requires a large amount of water permeation such as preparation of water for injection or hemodialysis filter. In addition, when applied to medical devices and the food industry, the permeation performance is greatly reduced during use due to the adsorption of separated substances or organic matters, there are many problems in practical application.

In addition, when the membrane of hydrophobic resin is preserved in water without drying, the water permeability is maintained, but the bacteria grow in water and cannot be used for medical or food use. A big problem arises in terms of back. When the hollow fiber membrane is manufactured, a potting process is performed, in which case drying is inevitable.

Therefore, in manufacturing a dry separator made of hydrophobic resin such as polysulfone-based, hydrophilization treatment is required by any method in order to maintain its water permeability.

Conventionally, there are a number of methods for hydrophilizing a polysulfone separator, for example, US Patent No. 4,340,482 discloses a method of grafting a hydrophilic monomer on the surface of the separator. However, this method tends to weaken the surface state of the separator and degrade the filtration performance.

In addition, British Patent No. 2,081,604 discloses a method of applying a hydrophilic polymer such as cellulose acetate to the surface of a separator, and the membrane obtained by such a method greatly improves the hydrophilicity of the membrane but greatly reduces the micropore size of the membrane surface. This causes a problem that the permeation performance of the membrane is lowered.

In Japanese Patent Laid-Open Nos. 60-246812 and 62-011503, a wetting agent solution composed of a hydrophilic substance such as glycerin, polyvinyl pyrrolidone or polyethylene glycol, or a surfactant is prepared after preparing a separator made of a hydrophobic resin. A method of producing a dry separation membrane made of a hydrophilic hydrophobic resin by immersion in and then drying is disclosed. However, this method has a problem of immersing for a long time of several hours to several tens of hours in order to evenly adhere the hydrophilic material to the surface and the inside of the membrane of the hydrophobic resin.

In addition, US Patent No. 5,240,480 discloses a method of imparting hydrophilicity to a separator by crosslinking a hydrophilic polymer such as polyvinylpyrrolidone on the surface of the separator. It cannot be used for industrial and medical equipment that requires a large amount of water transmission.

In addition, recently, Japanese Patent Laid-Open No. 59-186604 discloses a method of hydrophilizing a surface of a separator by plasma discharge treatment. However, this method has a good hydrophilic effect, but the plasma processing equipment is expensive and the power consumption is high, so the manufacturing price is greatly increased, which causes problems in practical use.

An object of the present invention is to solve the problem of the hydrophilization treatment method for maintaining the water permeability in manufacturing a dry separation membrane to produce a hollow fiber membrane with a conventional polysulfone-based polymer as described above, such as a separate expensive equipment It is an object of the present invention to provide a polysulfone-based hollow fiber membrane which can be used for equipment requiring a large amount of permeation because there is no need to reduce the resolution while improving the permeability excellent in hydrophilicity without the need.

Another object of the present invention is to provide a method for producing a polysulfone hollow fiber membrane as described above.

The polysulfone hollow fiber membrane of the present invention for achieving the above object is a hollow fiber membrane having an asymmetric single membrane structure composed of a polysulfone polymer, an organic solvent, a vinylpyrrolidone polymer, and a polyglycol, and has a hydrophilic compound of 1 to 50 weight and a metal salt. It is characterized by being hydrophilized, consisting of a hydrophilic aqueous solution containing 0.01 to 10 wt%.

In addition, the polysulfone-based hollow fiber membrane is a solution containing a glycol compound or a glycol compound as a spinning dope composed of a polysulfone polymer, an organic solvent, a vinylpyrrolidone polymer, and a polyglycol and an internal coagulating solution. Preparing a hollow fiber-type separator by spinning into a double tubular nozzle using air and then solidifying it with an external coagulant containing an organic solvent; And immersing the separation membrane in a hydrophilic aqueous solution containing 1 to 50 wt% of a hydrophilic compound and 0.01 to 10 wt% of a metal salt, followed by hydrophilization treatment.

The present invention contains a hydrophilic polymer in the spinning dope, prepared in the form of a membrane, and then immersed in a hydrophilic aqueous solution and subjected to hydrophilic treatment. In this process, crosslinking of the hydrophilic polymer contained in the spinning dope occurs and the components in the hydrophilic aqueous solution are The present invention relates to a method for manufacturing a hollow fiber membrane, which penetrates into the hollow fiber membrane so that the hollow fiber membrane can be hydrophilic.

A series of processes for preparing the hollow fiber membrane according to the present invention is as follows.

First, a polysulfone polymer is dissolved in an organic solvent, and then a spinning dope is prepared by adding a vinylpyrrolidone polymer and a polyglycol, which are hydrophilic polymers.

Here, the vinylpyrrolidone-based polymer and polyglycol play a role of forming a pore in the separator and have a high hydrophilic property, and thus tend to escape out of the hollow fiber membrane during solidification and washing after spinning.

It is preferable to use a vinyl pyrrolidone-based polymer having a molecular weight of 10,000 or more so that it can remain in the hollow fiber membrane.

It is preferable to use polyethyleneglycol, polyvinyl alcohol, etc. as polyglycol, and polyvinylpyrrolidone etc. as vinylpyrrolidone type polymer.

The organic solvent may be selected from m-cresol, chlorobezen, N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylacetamide and dimethylformamide, or may be used alone or as a mixture.

The content of the polysulfone polymer constituting the spinning dope is preferably 10-25 wt% in the spinning dope composition, and the total content of the vinylpyrrolidone polymer and polyglycol is 10-25 wt%.

After the spinning dope is prepared, the spinning dope and the internal coagulating solution are spun into the air by using a conventional double tubular nozzle. In this case, a glycol-containing compound or a solution containing a glycol compound is used. . As a glycol compound used at the time of internal coagulating liquid composition, the mixed solution of diethylene glycol and water is preferable.

The spinning dope and the internal coagulating liquid are discharged and spun through a conventional double tubular nozzle, and then deposited on the external coagulating liquid to solidify to form a hollow fiber separator.

As the external coagulating solution, a non-solvent of polysulfone is used, in particular water.

Then, the membrane is washed with water and wound, and then immersed in a hydrophilic aqueous solution to be hydrophilized and dried to prepare a hydrophilized polysulfone-based hollow fiber membrane according to the present invention.

The most important point in this invention is to hydrophilize by immersing the wound hollow fiber membrane in hydrophilic aqueous solution. In this process, crosslinking of the vinylpyrrolidone-based polymer included in the spinning dope occurs, and the components in the hydrophilic aqueous solution penetrate into the hollow fiber membrane, thereby making the hollow fiber membrane hydrophilic.

At this time, the hydrophilic aqueous solution immersing the wound hollow fiber membrane comprises a compound having a hydroxyl group (-OH) and an aqueous solution of a metal salt, the content of the compound having a hydroxyl group is 1 to 50% by weight in the hydrophilic aqueous solution, the concentration of the metal salt Is 0.01 to 10 weight.

Here, the compound having a hydroxyl group remains in the hollow fiber membrane and serves to impart hydrophilicity. Examples of specific compounds include alcohol, ethylene glycol, propylene glycol, glycerin, polyethylene glycol having a molecular weight of 600 or less.

In addition, the role of the metal salt in the hydrophilic aqueous solution composition can be largely divided into two. One is to catalyze the crosslinking reaction of the vinylpyrrolidone-based polymer, and the other is to maximize the dispersion of the compound having a hydroxyl functional group to minimize the degradation of the resolution during the hydrophilization process.

In general, separation by hydrophobic membrane is performed by the size of pore in the membrane, but in the case of aqueous solution, solute separation occurs to some extent by repulsive force. On the other hand, if the hydrophilization treatment is uneven, the water permeation amount is small due to the hydrophobic portion, but the degradation of the resolution that is transmitted through the hydrophilic portion without removing the solute in the aqueous solution occurs. However, when a small amount of the metal salt is present in the hydrophilic aqueous solution as in the present invention, the solubility of the compound having a hydroxyl group in water increases, so that the mixed solution becomes more uniform, and the mobility of the compound having a hydroxyl group also increases, thereby increasing the hollowness. It penetrates quickly into the desert. Therefore, the degradation of the resolution can be minimized and the processing time can be further shortened.

Alkali metal salts or alkaline earth metal salts may be used as the metal salts that play such a role.

Polysulfone hollow fiber membrane prepared by the method of the present invention, even if the hydrophilicity is improved, the resolution is not significantly lowered will have a much higher water permeability than other separation membrane having a similar removal ability.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

16 weights of polysulfone resins (P-3500: manufactured by Amoco Co., Ltd.), 11 weights of polyvinylpyrrolidone, and 5 weights of polyethylene glycol were added to 68 weights of dimethylacetamide, followed by stirring and dissolving to prepare a transparent spinning dope.

Separately, 70 wt% of diethylene glycol was added and dissolved in 30 wt% of water to prepare an internal coagulation solution.

The spinning dope and the internal coagulating solution were spun with a conventional double tubular nozzle to produce a hollow fiber having an outer diameter of 320 mu m and an inner diameter of 200 mu m.

The prepared hollow fiber was coagulated in a coagulation tank having an external coagulating solution through air, washed, and wound to prepare an untreated polysulfone hollow fiber membrane. At this time, water was used as the external coagulation solution.

The untreated polysulfone hollow fiber membrane was immersed in a hydrophilic aqueous solution containing 10 weights of glycerin and 1 weight of calcium chloride, treated at 50 ° C. for 5 hours, and dried to prepare a hydrophilized polysulfone hollow fiber membrane.

Example 2

After preparing an untreated polysulfone hollow fiber membrane in the same manner as in Example 1, it was immersed in an aqueous solution containing 5 weights of glycerin and 3 weights of sodium chloride, and then treated at 50 ° C. for 5 hours and dried to prepare a hydrophilized polysulfone hollow fiber.

Comparative Example 1

Polysulfone hollow fiber was prepared in the same manner as in Example 1, except that the polysulfone hollow fiber membrane was dried without hydrophilization to prepare a polysulfone hollow fiber membrane.

Comparative Example 2

Polysulfone hollow fiber was prepared in the same manner as in Example 1, except that an untreated polysulfone hollow fiber membrane was immersed in 5 weight aqueous solution of glycerin, treated at 50 ° C. for 5 hours, and dried to prepare a polysulfone hollow fiber membrane. .

Experimental Example

The transmittance and resolution of the polysulfone hollow fiber membranes prepared according to the examples and the comparative examples were measured, and the results are shown in Table 1 below.

Here, the water permeability was measured in a small module having an effective length of the hollow fiber membrane of 15 to 25 cm in a pure water of 1.0 kg / ㎠ pressure in a pressurized type (inside pressurizing type) at 25 ℃ at a time passed through the hollow fiber membrane. .

And, the resolution was measured by the solute rejection rate, after preparing the same module as the water permeability measurement, the concentration of 200ppm of myoglobin (Myoglobin, molecular weight 18,800) and obalbumin (Ovalbumin-albumin from chicken egg, molecular weight 45,000) The aqueous solution was permeated in the same manner as the above water permeability, and the concentration ratio of the protein in the stock solution and the permeate was measured using the UV spectrum, and then calculated using the following equation.

Solute exclusion rate () = (stock concentration-permeate concentration) / stock concentration × 100

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Permeability (mL / mmHg㎡hr) 670 720 40 660 Exclusion rate () Myoglobin 55 51 67 30 Ovalbumin 97 96 99 86

From the results of Table 1, the polysulfone-based hollow fiber membrane prepared according to the present invention can be seen that the permeability is significantly improved compared to the conventional separation membrane having excellent hydrophilicity, and the degradation of the separation does not occur.

As described in detail above, according to the present invention, the vinylpyrrolidone-based polymer and the polyglycol forming the pore in the spinning dope are contained, and spun with the internal coagulation solution and coagulated with the external coagulation solution to obtain an untreated polysulfone separator. , Polysulfone hollow fiber membrane prepared by immersing in hydrophilic aqueous solution composed of hydrophilic compound and metal salt has excellent hydrophilicity and excellent permeability, but can minimize degradation of resolution, so it is useful for industrial and medical equipment requiring large amount of permeation. Can be used.

Claims (7)

It is composed of a polysulfone polymer, an organic solvent, a vinylpyrrolidone polymer and a polyglycol, has an asymmetric single membrane structure composed of an inner surface and an outer surface, and is a hydrophilic aqueous solution containing 1 to 50 weight of a hydrophilic compound and 0.01 to 10 weight of a metal salt. Hydrophilized polysulfone hollow fiber membrane. The polysulfone hollow fiber membrane according to claim 1, wherein the hollow fiber membrane has a water permeability of 500 ml Hg m 2 hr or more, a myoglobin exclusion rate of 50 or more, and an ovalbumin exclusion rate of 95 or more. The polysulfone hollow fiber membrane according to claim 1, wherein the hydrophilic compound is at least one selected from alcohol, ethylene glycol, propylene glycol, glycerin, and polyethylene glycol having a molecular weight of 600 or less. The polysulfone hollow fiber membrane according to claim 1, wherein the metal salt is an alkali metal salt or an alkaline earth metal salt. Spinning dope composed of polysulfone-based polymer, organic solvent, vinylpyrrolidone-based polymer and polyglycol and a solution containing a glycol compound or glycol compound as an internal coagulating solution were spun into air with a double tubular nozzle and then organic Solidifying an external coagulation solution containing a solvent to prepare a membrane in the form of a hollow fiber; And A method of producing a polysulfone hollow fiber membrane comprising the step of immersing the separation membrane in a hydrophilic aqueous solution containing 1 to 50 weight of the hydrophilic compound and 0.01 to 10 weight of the metal salt. The method for producing a polysulfone hollow fiber membrane according to claim 5, wherein at least one selected from alcohol, ethylene glycol, propylene glycol, glycerin and polyethylene glycol having a molecular weight of 600 or less is used as the hydrophilic compound. The method for producing a polysulfone hollow fiber membrane according to claim 5, wherein an alkali metal salt or an alkaline earth metal salt is used as the metal salt.