JP3217842B2 - Hollow fiber high-performance microfiltration membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow fiber microfiltration membrane having a novel structure. More specifically, the present invention relates to a microfiltration membrane suitable for separating and purifying various viruses dispersed in an aqueous solution, or microorganisms including rickettsia, clademia, mycoplasma, and the like, and their crushed products, and separating and purifying physiologically active substances such as proteins. .

[0002]

2. Description of the Related Art Conventionally, 0.1 μm to 5 μm
As a method of removing fine particles of the degree, especially microbial particles,
Gel filtration, centrifugation, adsorption separation, precipitation, and membrane methods are used. In the gel filtration method, a target substance is diluted with a solvent used for the gel filtration, and therefore, it is difficult to apply it industrially. The centrifugation method can be applied only when the diameter of the microorganism particles is 10 μm or more and the viscosity of the aqueous solution is small. Although the adsorption filtration method can be used to remove a specific small amount of microorganism particles, this method cannot be applied to an aqueous solution in which a large number of microorganisms are dispersed in a large amount. Although the precipitation method can be used for treating a relatively large amount of an aqueous solution, it is impossible to completely remove microbial particles by this method alone. Among them, a membrane method using a microfiltration membrane is suitable for removing all microorganisms and can be processed in a large amount, so that the future is greatly expected. However, conventional microfiltration membranes do not have sufficient performance especially with respect to the permeability of low molecular weight physiologically active substances such as proteins, and often cause clogging inside the membrane, so that the recovery rate decreases remarkably, However, there is a problem that the filtration pressure increases and the filtration rate decreases. For this reason, the development of a high-performance microfiltration membrane having high permeation performance has been strongly desired especially in the pharmaceutical manufacturing field, the food industry field, and the like.

Hitherto, filtration membranes having various structures have been invented with respect to hollow fiber microfiltration membranes composed of high molecular compounds such as polysulfone, polyvinylidene fluoride, cellulose acetate, polyacrylonitrile, polymethyl methacrylate, and polyamide. For example, JP-B-63-36805
JP, JP-A-63-100902, JP-A-63-100902
JP-A-164602, JP-A-59-189903, JP-A-59-183761 and the like. Such a hollow fiber microfiltration membrane generally has a so-called symmetric membrane in which the shape or diameter of pores on the inner surface and outer surface of the hollow fiber membrane does not substantially change, and a pore diameter that is continuous or discontinuous in the film thickness direction. It is classified as a so-called asymmetric membrane in which the pore diameter changes on the inner surface or outer surface of the membrane and the pore diameter on the other surface. Among them, the symmetric membrane is disclosed in, for example, JP-A-59-189903. However, in filtration, the entire membrane exhibits a large resistance to the flow of the fluid, and only a small flow velocity can be obtained. Since the shape of the pores on the surface is irregularly stitched, there is a disadvantage that solute clogging is likely to occur.

On the other hand, an asymmetric membrane has a structure in which a layer having a small pore size is provided on one of the inner surface and the outer surface of the hollow fiber membrane, and a layer having pores having a relatively larger pore size is provided on the other surface. In the membrane having such a structure, by flowing a filtrate from a surface having a small pore size to a surface having a large pore size, the smallest fine particles that can be removed by filtration are removed by filtration on the surface having a small pore size. The filtration resistance of the part is small and the filtration efficiency is very excellent. However, in the conventional asymmetric membrane, despite the fact that a surface having pores having a small pore diameter for substantially retaining filtration is extremely important, the shape of the pores is very irregular and non-uniform.
No. 5, JP-A-63-100902, the shape of the pores on the other surface is relatively large even if they have a relatively regular and uniform pore diameter of a circle or an ellipse. Because the shape is irregular and non-uniform, the shape of the hole changes discontinuously from the inner surface or outer surface to the other side, or the shape of the hole changes in the middle even if it changes continuously. It just gets lost. For this reason, the filtration characteristics vary in a complicated manner depending on the type and shape of the solute. Therefore, when filtering a solution containing a plurality of solutes having various shapes and sizes, clogging occurs inside the membrane and pores are closed. Or a problem that sharp fractionation characteristics cannot be obtained.

[0005]

The problem to be solved by the present invention is to separate and remove various viruses or microorganisms including rickettsia, clademia, mycoplasma, etc. dispersed in an aqueous solution, and their crushed products to remove proteins and the like. An object of the present invention is to provide a high-performance microfiltration membrane having a completely novel membrane structure, which has very little clogging of solutes inside the membrane and has a high filtration ability, which is suitable for separation and purification of physiologically active substances.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above.
A hollow fiber filtration membrane mainly composed of a polymer, characterized by having circular or elliptical holes on its inner surface and outer surface. In the present invention, the average pore diameter of the pores on the inner surface is at least 1.0 μm, and the average pore diameter of the pores on the outer surface is at least 0.01 μm.

Further, in the present invention, the structure of the thickness portion of the membrane from the outer surface to the inner surface of the hollow fiber has a network structure, and the average pore diameter of the pores formed from the network structure is from the outer surface to the inner surface. The inclination type asymmetric structure always increases toward the center, and the degree of inclination is at least 1.0% or more. Here, the inclination is a value represented by Expression 1.

[0008]

(Equation 1)

The high-performance microfiltration membrane of the present invention uses a solution containing a polymer, an additive and a solvent as main components as a stock solution for film formation, and discharges the stock solution from a spinneret to a coagulation bath using an internal injection solution during spinning. Can be produced. The polymer used in this case, rather than by as long as it can be wet film,
Kaoru aromatic polysulfone, and the like.

On the other hand, the additive may be any as long as it is compatible with the solvent and does not dissolve the polymer. For example, if the polymer is a polysulfone-based polymer, tetraethylene glycol, ethylene glycol, triethylene glycol, nitrobenzene, tetrahydrofuran, Examples include dioxane, dimethyl carbonate, diethyl phosphate, polyvinyl pyrrolidone, cellulose derivatives, isopropyl alcohol, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone and the like. The solvent may be any as long as it dissolves both the polymer and the additive, for example, a polysulfone-based polymer,
Polyvinylidene fluoride-based polymers include dimethylsulfoxide, N-methyl-2-pyrrolidone, dimethylacetamide and the like.

The concentration composition of the polymer in the film forming solution is as follows:
It is sufficient that the film can be formed and has a performance as a film, and it is 10 to 30% by weight. Further, in order to obtain high water permeability and a large molecular weight cut-off, the polymer concentration should be lowered, and in this case, it is 10 to 20% by weight. The amount of the additive depends on the type and molecular weight of the additive, but is 1 to 30% by weight.
And preferably 1 to 25%. It is also possible to add a fourth component such as water, salt or the like for the purpose of controlling the viscosity and dissolution state of the film-forming stock solution, and the type and amount of addition may be arbitrarily determined depending on the combination.

Further, the state from the internal injection solution used at the time of film formation and the state from the spinneret to the coagulation bath have the ability to separate the polymer solution into one liquid and one liquid phase, and correspond to the polymer concentrated phase after the phase separation. Any condition may be used as long as the volume ratio of the polymer dilute phase is smaller than 1. Such an internal injection liquid is, for example, 95% by weight or more of dimethylacetamide in the case of a polysulfone-based polymer, and the state from the spinneret to the coagulation bath is an atmosphere with a humidity of 95% or more.

Examples of the present invention will be described below, but the present invention is not limited thereto.

[0014]

Example 1 28.0 g of polyvinylpyrrolidone was added to 68.0 g of dimethylacetamide (hereinafter abbreviated as DMAC).
(Nacalai Tesque K-30), polysulfone resin (AMOCO Co. Udel P-3500: hereinafter PS abbreviated) 18 g was added and the dissolved 5 hours at 60 ° C. electrostatic置脱foam after casting dope.

[0015] This film forming stock solution was added to DMAC / H ₂ O
= 95/5 (wt / wt) using a mixed solution having an inner diameter of 0.64 mm and an outer diameter of 1.04 mm. After passing through a water bath for coagulation, the membrane was washed with water by a usual method and wound around a scab to obtain a hollow fiber membrane. When the membrane structure of this hollow fiber was analyzed by SEM and image analysis, the average pore diameter of the pores on the inner surface was 10.4 μm, the average pore diameter of the pores on the outer surface was 0.76 μm, and both were circular. The inclination of the film thickness structure was 4.82%. The average pore diameter was calculated as the diameter of an equivalent circle from the average area of the pores obtained from the image analysis.

Using this membrane, a viable cell culture solution (Pseudo
omonas Diminuta 0.5 μm × 1-4 μm
m The number of raw aquatic bacteria = 105 cells / ml) was subjected to an external pressure filtration method for 1 hour. As a result, the flux retention rate of the viable bacterial culture was 60% or more.

[0017]

[Comparative Example 1] A stock solution similar to that used in Example 1 was added to an injection solution by DM.
Using a mixed solution of AC / H ₂ O = 75/25% (wt / wt), spinning was performed under the same conditions as in Example 1 to obtain a hollow fiber membrane. When the membrane structure of this hollow fiber was analyzed by SEM and image analysis, the average pore diameter of the pores on the inner surface was 1.
The average pore diameter of the holes on the outer surface was 0.37 μm, and the shape of the holes on the outer surface was circular, but the shape of the holes on the inner surface was irregular mesh. The inclination of the film thickness structure was 0.46%. The average pore size was calculated in the same manner as in Example 1.

Using this membrane, a viable cell culture solution (Pseud)
omonas Diminuta 0.5 μm × 1-4 μm
m The number of raw aquatic bacteria = 105 cells / ml) was subjected to an external pressure filtration method for 1 hour, and the flux retention was reduced to 50% or less.

[0019]

The hollow fiber membrane of the present invention is a polysulfone microfiltration membrane having a novel membrane structure having very low solute clogging inside the membrane and having a high filtration ability. It is extremely suitable for separating and removing microorganisms including rickettsia, cladmere, mycoplasma, etc. and their crushed products, and for separating and purifying biologically active substances such as proteins.It can be used in general industrial fields such as drug production and food production. Of course, it can be sufficiently used in medical applications.

[Brief description of the drawings]

FIG. 1 is an SEM image (magnification: 10,000 times) of the outer surface of a hollow fiber membrane obtained in Example 1.

FIG. 2 is an SEM image (magnification: 10,000 times) of the outer surface of the hollow fiber membrane obtained in Comparative Example 1.

FIG. 3 is an SEM image (1000 × magnification) of the inner surface of the hollow fiber membrane obtained in Example 1.

FIG. 4 is an SEM image (1000 × magnification) of the inner surface of the hollow fiber membrane obtained in Comparative Example 1.

FIG. 5 is a SEM image (35) of the membrane annular cross section obtained in Example 1.
0 times).

FIG. 6 is a SEM image (35) of a film annular cross section obtained in Comparative Example 1.
0 times).

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01D 71/68 B01D 69/08

Claims (1)

(57) [Claims] 1. A hollow fiber filtration membrane containing aromatic polysulfone as a main component, having circular or elliptical pores on its inner surface and outer surface, and having an average pore diameter on the inner surface.
The diameter is 1.0μm or more, the average pore diameter of the pores on the outer surface is 0.01μ
m or more, and the average pore diameter of the pores is from the outer surface to the inner surface.
Is an asymmetrical structure that always increases.
A high-performance hollow fiber microfiltration membrane having a degree of 1.0% or more .