JPS6121702A - Porous film and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain porous film of high mechanical strength having a well- balanced permeability and removal efficiency by forming a thin film layer through the erosion by a high-quality solvent commonly suitable to a porous thin film layer polymer and a porous support film polymer. CONSTITUTION:An acetone solution of polyvinylidene fluoride is coated on a substrate such as glass plate to form a thin film layer. Next, a mixed solvent of dimethylformamide and acetone is used to resolve polyvinylidene fluoride. This polymer solution is cast on the thin film layer. It is left alone for approx. 10 seconds to evaporate the solvent content of the polymr solution and then the substrate is immersed in a less active solvent such as isopropyl alcohol. After tnis the substrate is taken out and dried by an infrared ray lamp and then the film is peeled off the substrate while it is immersed in water. The porous film 6 thus obtained is an anisotropic porous film consisting integrally of a thin film layer 2 having micropores and a support layer 5 having comparatively larger pores.

Description

Detailed Description of the Invention [8] Background of the Invention [Field of the Invention] The present invention relates to a porous membrane and a method for producing the same. Specifically, the present invention relates to a porous membrane made of polyvinylidene fluoride resin that has an excellent balance between water permeability and removal efficiency and excellent mechanical strength, and a method for manufacturing the same.

[Prior Art] Conventionally, porous membranes of cellulose derivatives, particularly cellulose acetate, having high water permeability have been common as polymeric porous membranes used for various types of filtration, dialysis, and the like. However, such cellulose derivatives have poor resistance to acids, alkalis, organic solvents, etc.
Furthermore, since it has the disadvantage of being easily deformed by heat, pressure, etc., the range of its usage conditions is greatly limited.

In recent years, porous membranes of fluororesins such as polyvinylidene fluoride and vinylidene fluoride-tetrafluoroethylene copolymers have been attracting attention as alternatives to porous membranes of these hillulose derivatives.

Conventionally, methods for manufacturing porous membranes made of fluororesin include dissolving the resin in a solvent, spreading it into a predetermined shape, evaporating a portion of the solvent, and then using a nonsolvent that is miscible with the solvent. There is a wet method in which the porous membrane is obtained by immersing the resin in the solvent to extract the solvent and completely evaporating the solvent and non-solvent, and a wet method in which the resin is mixed with the solvent and a non-solvent that is miscible with the solvent from the beginning to form the desired porous membrane. There is a dry method in which a porous membrane is obtained by spreading the membrane into a shape and completely evaporating the solvent and nonsolvent.

In the wet method, evaporation of the solvent before the dipping process occurs from the surface of the spread resin solution that comes into contact with air, which causes resin aggregation near the surface.

In this state, the solvent is extracted by the non-solvent into the unevaporated portion, so that the resulting porous membrane has a so-called anisotropic porous membrane in which the pore diameter at the surface portion is smaller than the pore diameter at the lower portion.

Therefore, a membrane with higher water permeability than an isotropic porous membrane can be obtained, but this wet soaking process 111! Because the performance of each solvent varies greatly depending on the difference in evaporation time of the previous solvent, it is difficult to obtain a uniform product, and it is particularly difficult to design and cover a porous structure with fine pores.

On the other hand, in the dry method, the ratio of solvent and nonsolvent changes due to evaporation, and when the composition reaches a composition that causes phase separation of the dissolved resin, gelation or crystal precipitation occurs, and when the evaporation is complete, the gaps between the resin particles become pores. A film with the following properties is obtained. A porous membrane produced by a dry method can be relatively easily obtained even if the porous membrane has a relatively small pore diameter, but the porous membrane is isotropic and has low water permeability.

Furthermore, no matter which method is used, porous fluororesin membranes have inferior water permeability and mechanical strength compared to cellulose derivatives with a network structure due to their crystalline structure. It has been impossible to maintain both good water permeability and good mechanical strength while having the same properties.

Various studies have been conducted to improve the low water permeability and low mechanical strength of porous membranes made of fluorine resin. For example, JP-A-52-154
No. 862 discloses a method for producing a porous membrane of vinylidene fluoride-tetrafluoroethylene copolymer, polyvinylidene fluoride, and a mixture thereof, in which the mechanical strength of (i) is increased by steaming.

Using solvents with different partial pressures, resins with different compositions, I#1 fats with different degrees of polymerization, or resins at the interface of solvation, a part of the resin is dissolved in the solvent evaporation step. Alternatively, there is a dry method that increases the mechanical strength by sticking to the swelling resin, and JP-A-49-126572 describes a porous membrane of polyvinylidene fluoride! ! Similarly, a wet method is disclosed in which the mechanical strength is increased using a quick-drying method and a slow-drying solvent. However, although these methods can be expected to improve the mechanical strength to a certain extent, the water permeability tends to decrease due to a decrease in porosity.

Therefore, to date, porous membranes made of fluororesin have advantages such as excellent acid resistance, alkali resistance, solvent resistance, and heat resistance, but have low water permeability and low mechanical strength. , its functions were not fully demonstrated.

(1) Purpose of the Invention Accordingly, an object of the present invention is to provide a novel porous membrane and a method for producing the same. Another object of the present invention is to provide a method for producing porous membranes J3 and A made of polyvinylidene fluoride resin that have an excellent balance between water permeability and removal efficiency and excellent mechanical strength. A further object of the present invention is to provide a porous membrane made of polyvinylidene fluoride resin in which a thin membrane with a small pore diameter and a support layer with a large pore diameter and high water permeability are integrated, and a method for producing the same. Another object of the present invention is to provide a porous membrane suitable for use as a fufinal filter, a pharmaceutical filter, etc., and a method for producing the same.

The present inventors have developed a method for obtaining a polyvinylidene fluoride resin porous membrane that has an excellent balance between water permeability and removal efficiency and has excellent mechanical strength. We investigated a method for manufacturing a flexible porous membrane by integrating a thin membrane with a support layer with large pores and high water permeability.

A method for producing an anisotropic porous membrane that increases mechanical strength and water permeability while maintaining a certain removal efficiency is disclosed in JP-A-57-102336, for example. The material is immersed in a solution that combines resin, solvent, and nonsolvent to form micropores, and after drying, it is separated into two layers.
A method for producing circumferential porous Ill is disclosed. However, in this method, the formation of anisotropy may be extremely limited because the micropore-forming solution also penetrates into the pores of the porous substrate during the erosion process.

Furthermore, in JP-A-58-154051, crystalline skin can be formed by casting with a metastable polymer dope useful for polysulfones, polyimides, polycarbonates, polyacrylonitrile, polyquinoxalines, and polyquinolines. A method for forming a circumferential porous membrane to form a network-structured support layer is disclosed. However, it is practically difficult to apply this method to highly crystalline fluororesins.

In view of the current situation, the present inventor has conducted intensive research to solve the above-mentioned objects, and has thus arrived at the present invention.

■0 Structure of the Invention The above objects are made of a porous thin film layer of a polymer, and a porous support film made of a homogeneous polyester film having a good solvent common to the polymers and coated on at least one side of the thin film layer. The pores of the porous thin film layer are pores eroded by a good solvent common to the polymer of the thin film layer and the polymer of the support film layer that were contained in the pores of the porous support film, and The pores in the thin film layer and the pores in the support layer are formed in communication with each other.

The present invention also provides an anisotropic porous membrane in which the polymer forming the porous thin film layer and the porous support membrane is polyvinylidene fluoride. The present invention further provides an anisotropic porous membrane in which the thickness of the anisotropic porous membrane is 50 to 200 μm, and the thickness ratio of the thin film layer to the supporting membrane layer is 1:500 to 1:20000. It is something. The present invention also provides an anisotropic porous membrane in which the thin film layer has an average pore size of 0.01 to 0.6 μm and the support layer surface has an average pore size of 0.1 to 2.0 μm.

In addition, the purpose of Wangji is to form a polymer thin film layer in advance in the basic style, then cast a polymer solution of the same polymer dissolved in a good solvent onto this thin film, evaporate a part of the solvent, and then Alternatively, this can be achieved by a method for producing an anisotropic porous membrane by immersing it in a non-solvent and drying it.

The present invention also provides a method of forming a thin l1w layer of polyvinylidene fluoride on a substrate in advance, then chitosting a polymer solution of polyvinylidene fluoride dissolved in a good solvent onto this thin film layer, and after evaporating a part of the solvent. 1 shows a method for producing an anisotropic porous membrane by immersing it in a poor solvent or non-solvent and drying it. The present invention also describes a method of manufacturing an anisotropic porous membrane in which the thin film layer is obtained by spraying a polymer solution onto a substrate. The present invention also provides a method for producing an anisotropic porous membrane in which the good solvent is a mixture of a quick-drying good solvent and a slow-drying good solvent. Furthermore, the present invention provides a method for producing an anisotropic porous membrane in which the weight ratio of a quick-drying good solvent to a slow-drying good solvent is 50:50 to 95:5. The present invention also provides a method for producing a φ anisotropic porous membrane in which the polymer concentration of the polymer solution cast onto the thin film layer is 15 to 25% by weight. The present invention also provides a method for producing an anisotropic porous membrane in which the polymer concentration of the polymer solution sprayed onto the substrate is 0.01 to 1% by weight. The present invention also provides that the good solvent for the polyvinylidene fluoride polymer solution is a quick-drying solvent selected from the group consisting of acetone, methyl ethyl ketone, and atrahydrofuran, and a slow-drying solvent selected from the group consisting of dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. This shows a method for producing an anisotropic porous membrane using a mixed solvent consisting of a dry prickly solvent.

(1) Specific structure of the invention Next, the present invention will be explained in detail. The present invention relates to an anisotropic porous membrane in which a thin layer having micropores, which is essentially a part of a filter, and a support layer having a large pore size and a high water permeability zone are integrated, and a method for manufacturing the same.

The method for producing a commercially available porous membrane of the present invention includes reluulose-based,
It is also useful as a method for producing anisotropic porous membranes made of polymers such as polyamide, polycarbonate, and polyJ-ethylene, and is particularly useful as a method for producing anisotropic porous membranes made of fluororesin polymers. An example of the fluororesin polymer used in the method for producing an anisotropic porous membrane of the present invention is polyvinylidene fluoride. In addition to polyvinylidene fluoride homopolymers, the polyvinylidene fluoride includes copolymers based on vinylidene fluoride with ethylene tetrafluoride, methyl acrylate, propylene, etc., and mixtures of these and other polymers. The method for producing an anisotropic porous membrane of the present invention includes several steps as shown below.

. In the first step, on a substrate 1 with a smooth surface such as a glass plate,
This is the step of forming a thin polymer film N2. The thin film layer 2 of polymer is formed by spraying the polymer solution onto the substrate as shown in FIG. 1(a), or alternatively by chitosting the polymer solution onto the substrate. The polymer concentration of this polymer solution is preferably 0.001 to 1% by weight, preferably 0.005 to 0.05% by weight.

The solvent for this polymer solution is desirably one that can dissolve the polymer at a temperature below its melting point, particularly one that dries quickly. For example, when the polymer is polyvinylidene fluoride, examples of the solvent include acetone, methylpropylketone, diethylketone, methylpropylketone, methylbutylketone, methylisopropylketone, ketones such as cyclohexanone, tetrahydrofuran, tetrahydrofuran, .4-Di(N) etc., preferably acetone, methyl chlorine ketone and tetrahydrofuran, most preferably acetone. Dissolution of polyvinylidene fluoride in such a solvent is usually carried out at 50 to 56°C for 1 to 4 hours.

Such a polymer solution is deposited on the substrate 1 to a thickness of 500 to 500 nm.
000 μm sprayed or coated with a thickness of 0
．． A thin film layer 2 with a thickness of 0.001 to 1 μm, preferably 0.01 to 0.1 μm is formed.

In the second step, a polymer of the same quality as the polymer forming the AIJ film layer 2 is dissolved in a good solvent on the polymer thin film R2 formed on the substrate 1 as shown in Figure 1(b). This is the step of casting the obtained polymer concentration 3 to form a support layer. The polymer concentration of the polymer solution 3 dissolved in this good solvent is 15 to 25% by weight, preferably 16 to 5% by weight.

The solvent for this polymer solution 3 is one that can dissolve the polymer in a humidity range below its melting point, and can be used as a solvent that is quick-drying or can be used alone, but preferably as a mixture of a quick-drying solvent and a slow-drying solvent. It is. In the case of a mixture of fast-drying and slow-drying solvents, the weight of the fast-drying solvent and the slow-drying solvent is
50:50-95:5, preferably 70:30
A mixed solvent having a ratio of ~80:20 is desirable.

For example, when the polymer is polyvinylidene fluoride, examples of quick-drying solvents include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isopropyl ketone, ketones such as Schiff[1 hequinanone, and tetrahydrofuran. , tetrahydrofuran, 1,71-dioquine-4)-one, etc., preferably acetone, meboolethyl ketone, tetrahydrofuran, and slow-drying solvents such as dimethylformamide, dimethylace1-amide, etc. , dimethylacetamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, tetramethylurea, dimethylsulfoxide and the like, preferably dimethylformamide, dimethylacetamide and dimethylsulfoxide. Furthermore, when polyvinylidene fluoride is a polymer, the most preferable solvent is a heavy duty ratio of aton and dimethylformamide: eo: 40 to 90:
It is a mixed solvent of 10 to 10, especially when the polymer concentration is 16 to 18.
% by weight. Dissolution of polyvinylidene fluoride in such a solvent is usually carried out at 51 to 55°C for 1 to 4 hours.

Such a polymer solution 3 is cast onto a thin film layer 2'' formed on the substrate 1 to a thickness of 150 to 500 μm, preferably 300 to 500 μM.

Here, since the polymer solution 3 and the thin film layer 2 both contain the same polymer, they have good wettability and can be integrated, but there is a clear boundary surface at the interface between the polymer solution 3 and the thin film layer 2. Zuru. Further, the thin film layer 2 is again immersed in the solvent due to the transfer of a portion of the solvent in the polymer solution.

The third step, shown in FIG. 1(C), is a step in which a portion of the solvent in the polymer solution 3 cast onto the thin film layer 2 is evaporated. At this stage, evaporation =
1 At the interface between the sanded solution 2 and the surrounding atmosphere,
occurs more quickly than inside the solution. The conditions of this third stage are important in determining the water permeability and removal rate of the final product. In other words, if the solvent evaporation time in the third step is long, the molecules in the solution will aggregate, and the pore diameter of the support layer 5 in the final product will become small. The humidity at this time is also an important factor.

Therefore, the solvent evaporation conditions are determined so that the ratio of the pore diameter of the micropores of the thin film layer 2 to the pore diameter of the insect retentive layer 5 in the final product is good, and is usually at 10 to 40°C for 1 to 15 seconds. ,
``Preferably, the temperature is 20 to 30°C for 3 to 10 seconds.

The fourth step is immersion in a poor solvent or non-solvent; -medium/＼.

It is a stage. Immediately after the end of the third step, the substrate 1 carrying the thin film layer 2 and the polymer solution 3 cast thereon is immersed in an immersion bath 5 containing an anti-solvent or non-solvent, as shown in FIG. 1(d). immersed inside. The poor solvent or non-solvent is one that is homogeneously compatible with the solvent used to dissolve the polymer, and alone can hardly or not dissolve the polymer at all. Furthermore, when a quick-drying solvent and a slow-drying solvent are used, it is desirable that the steam wax partial pressure of the non-solvent is between that of the quick-drying solvent and the slow-drying solvent. For example, when the polymer is polyvinylidene fluoride, non-solvents or poor solvents include water, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, 5aC-butyl alcohol, te
Alcohols include rt-butyl alcohol, pentyl alcohol, hexyl alcohol and A-methyl alcohol, preferably methyl alcohol, ethyl alcohol, isopropyl alcohol and propyl alcohol, and swamp is also preferably isopropyl alcohol. In addition, there is a mixture of the above-mentioned non-solvent and the above-mentioned good solvent used to dissolve the polymer, and in the case of this mixture,
The content of the good solvent relative to the nonsolvent is 60 to 90% by volume, preferably 70 to 80% by volume.

By being immersed in such a non-solvent or poor solvent, the solvent in the polymer solution 3 is removed by diffusion, gelation progresses, and polymer particles are precipitated. In this case, when both fast-drying and slow-drying solvents are present, gelation proceeds in the presence of partially dissolved polymer, and the mechanical strength of the bonds between the precipitated polymer particles exists. Enhanced by the action of polymers.

In this way, a porous support layer 5 having a relatively large pore size is formed from the polymer solution 3. This mechanism is almost the same as the mechanism of porosity formation in general wet methods.

On the other hand, lfi! i! The solvent contained in layer 2 is also reduced by the poor solvent or non-solvent, and as a result, the thin film layer 2
Micropores are formed in the

The immersion sufficiently diffuses the good solvent contained in the polymer solution 3 and the thin film layer 2 into the poor solvent or non-solvent to form the support layer 5 having relatively large pores and to form fine pores in the thin layer 2. continued long enough to form, usually 3 to 2
It is carried out for 0 minutes, preferably for 5 to 10 minutes.

The fifth stage is the drying stage. After the fourth stage of immersion is completed, the substrate 1 carrying the porous membrane 6 consisting of the formed thin film layer 2 and support layer 5 is taken out from the immersion bath 4, and the remaining solution 9X-13 and the remaining impurity are removed. It is passed to a drying stage to completely remove the solvent or non-solvent. Drying usually takes about 4
It is carried out at a temperature of about 0° to 80° C. for 5 to 10 minutes using an oven or an infrared lamp. FIG. 1(C) shows the drying stage using an infrared lamp 7. FIG.

After drying is completed, the porous membrane 6 is peeled off 4 from the supporting substrate 1 using an appropriate means, thereby completing the manufacturing process.

The porous membrane 6 of the present invention, which can be obtained as described above, has a thin film layer 2 having fine pores and a supporting layer 5 having relatively large pores, and has a so-called anisotropic structure. ing.

That is, in the anisotropic porous 116 of the present invention, the thin film H
The holes 2 are formed by being eroded by the good solvent contained in the pores of the support layer 5, and are therefore smaller than the pores of the support 115.
The holes in the support layer 5 communicate with each other to form a through hole, so that the hole in the support layer 5 exhibits creditability. Figures 4(a) and 4(b) show a thin film of an embodiment of the anisotropic porous membrane of the present invention. An electron micrograph of the side surface of the layer (Fig. 4(a) is a magnification of 100x, and Fig. 4(b) is a magnification of 300x), and Fig. 4(C) is an electron micrograph of the side surface of the support layer. times).

It is clear from the m/1(a) to (0) diagrams that the porous membrane of the present invention exhibits anisotropy.

The polymer forming the anisotropic porous membrane of the present invention may be a cellulose-based, polyamide-based, polycarbonate-based, polyethylene-based polymer, etc., as described in the above manufacturing method, but is preferably a fluororesin-based polymer. Polymers are preferred. As the fluororesin polymer, there are those mentioned in the above manufacturing method. Support I! ! The polymers constituting 5 and the thin film layer 2 do not need to be the same, as long as they are of the same quality and have a common good solvent.

The anisotropic porous membrane 6 of the present invention has good mechanical strength because it is relatively thick, and has good water permeability because the support layer 5 has relatively large pores, and the target particles The capture of is achieved by the micropores of the thin film layer 2. Moreover, since particles relatively larger than the target particles are captured in stages by the pores of the support layer 5, the clogging of the micropores of the thin film layer 2 is eliminated by 8:1, thereby improving the filtration efficiency. The anisotropic porous membrane 6 of the present invention typically has a thickness of 50 to 200 μm, preferably 100 to 150 μm, and has a thin film layer 2 and a support layer 5.
．． ! =+7) Layer/'7 ratio hN: 500~1:2
0,0001 preferably to 1:1000・1:10
．． 000, and the thin film layer 2 has an average pore diameter of 0.01 to 0.6
μm1 is preferably 0.2 to 0.6 μm, and the support layer 5
has a surface average pore diameter of 0.1 to 2.0 μm, preferably 0.
．． It has a characteristic of having a porosity of 2 to 1.0 μm and a porosity of 75 to 80%.

The anisotropic porous membrane of the present invention is used in various fields due to its excellent water permeability, filtration efficiency, and mechanical strength.
In particular, the polyvinylidene fluoride porous membrane obtained by the production method of the present invention has, in addition to the above-mentioned properties, excellent acid resistance, alkali resistance, solvent resistance, and Since it enjoys properties such as heat resistance and radiation resistance, it can be used in fields where cellulose 211 membranes have not been used in the past. Examples of major applications include final filters and pharmaceutical filters for medicinal solutions and infusions, membranes for artificial organs such as artificial lungs and artificial kidneys, membranes for electrolytic cells, batteries, etc., and membrane caps for treating waste liquids such as acid and alkaline waste liquids. There is.

Next, the q-body effect of the lenticular porous membrane of the present invention will be explained using the case of a final filter for infusion as an example.

As shown in FIG. 2, in the middle of the infusion tube 9 that communicates with the infusion bag 8, there is a! of the present invention! ! A final filter 10 incorporating an anisotropic porous membrane 6 obtained by the manufacturing method is sterilized and attached. The infusion solution is dripped from the infusion bag 8 through the infusion tube 9 into the final filter 10. Fungi, bacteria, fine particles, etc. mixed into the infusion are captured by the anisotropic porous membrane 6 of the file filter 10, and only the purified infusion passes through the final filter 10 and the infusion tube 9. The injection tube 11 is delivered into the vein of the patient 12. Therefore, complications caused by fungi, #1 bacteria (fine particles, etc.) mixed into the infusion can be prevented.

FIG. 3 shows a sectional view taken along line II of the lenticular porous membrane 6 according to one embodiment of the present invention. In addition, 1st (a) ~
1 (e) In the figure, thin film IPJ2, polymer solution 3
and the support layer 6 are exaggerated.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Polyvinylidene fluoride (trade name: 301, Mitsubishi Oil & Fat Chemical Co., Ltd.) was dissolved in acetone to 0, oi*a%.

As shown in FIG. 1(a), a 4R sprayer was used to coat a glass plate to a thickness of 0.01 μm.

18@fi parts of polyvinylidene fluoride (same as above) were dissolved in 82 parts of a mixed solvent consisting of 25% dimethylboramide and 75% acetone with stirring at a temperature of 54° C. for 4 hours.

After cooling to room temperature for 1 hour, a layer of 0.5
I poured it into On+m.

After being left for 10 seconds, it was immersed in isopropyl alcohol at 30°C. After 10 minutes, it was taken out, dried using an infrared lamp at 60° C. for 10 minutes, and peeled off from the glass by immersing it in water.

Water permeability, porosity, bubble point, and
The cutting rate of 0.22μ polystyrene particles was investigated. The results are shown in Table 1.

The water permeability is the water permeability at a pressure of 10 psi (initially replacing with methanol and then flowing distilled water (20°C)), and the cut rate is using a 0.22 μ styrene standard solution and changing the concentration of the stock solution to 1.7 x 10 It is measured as /.

Comparative Example 1 A porous membrane was prepared in the same manner as in Example 1, except that the glass plate was not coated with polyvinylidene fluoride # membrane,
A similar test was conducted. The binding is shown in Table 1. .

Comparative Example 2 A test similar to Example 1 was conducted using De17Po7G VHP (0.22μ) manufactured by Millibore. The results are shown in Table 1.

(The following is a blank space) Ax's 0 0 11K Go - Example 2 Polyvinylidene fluoride (mentioned above) was dissolved in acetone to a concentration of 0.005% by weight. In order to improve the uniformity of the thin film, it was coated onto a glass plate to a thickness of 0.05 μm using an improved blowing device compared to that used in Example 1. After this, a support membrane layer was formed in the same manner as in Example 1 using the same method as Example 1 to obtain a two-layer membrane. The results of measuring the cut rate are shown in Table 2.The side surfaces of the thin film layer of the 1q porous membrane were magnified 1000 times and 300 times, and the side surface of the support layer was magnified 100 times with an electron microscope. The results are shown in FIG. 4(a), FIG. 4(b), and FIG. 4(C), respectively.

Comparative Example 3 A porous film was prepared in the same manner as in Example 2, except that polyvinylidene fluoride-dipped film was not coated on a glass plate, and the same test was conducted. The results are shown in Section 2A. In addition, the results of 1000 times magnification and imaging of the glass substrate side and opposite sides of the obtained porous membrane with an electron microscope are shown in Section 5 (a).
) and FIG. 5(b).

Comparative example 4 Duravore QhiWP (0.22μ polyvinylidene fluoride parent wood treated membrane) manufactured by Millipore Comparative example 5 MF-membrane GSWP (0: 22μ hillulose mixed ester) Comparative example manufactured by Millipore 6 TM-/l (0.22μ nitro Cellulose) The above three types of products manufactured by Toyo Roshi were subjected to the same tests as in Example 2, and the results are shown in Table 2.

(Left below) Table 2 Bubble porosity Water permeability Point Cut rate Example 2. ．． 7.5.4'2'3. θ 1
．． /l, '95 twin comparative example 378.8 28.
j 1.4 30 or more” 4 67.9
' 8.2 3.6 70〃5 77.8
10,5,4. 'O'-G.

lI'6 73,1 11.8 '1,4
70.0 Effects of the Invention As described above, the present invention provides a porous thin film layer of a polymer, and a porous polymer comprising a porous thin film layer of a polymer, and a homogeneous polymer having undulating fibers in common with the polymer with wave troughs on at least one side of the thin film layer. The porous thin p! The pores in the layer are pores eroded by a good solvent that are included in the pores of the porous support membrane and are common to the polymer of the S membrane layer and the polymer of the support membrane layer, and are pores that are eroded by a good solvent that are included in the pores of the porous support membrane. The anisotropic porous membrane is characterized in that it has through-holes formed in communication with the pores of the support layer, and that the good solvent is completely removed. , a 1V layer of a polymer is formed in advance on the substrate 1-, and then a polymer solution of a polymer of the same quality as the above polymer dissolved in a good solvent is cast onto this f thin film m, and after evaporating a part of the solvent, This method of manufacturing an anisotropic porous membrane consists of immersing it in a poor solvent or non-solvent and drying it, so it has a predetermined separation ability, an excellent balance between water permeability and removal efficiency, and mechanical strength. It is possible to provide an excellent porous membrane. In particular, when polyvinylidene fluoride resin is used as a polymer, an anisotropic porous polyvinylidene fluoride membrane that is chemically and physically stable and has the excellent properties described above, which has not been previously available, can be produced. Can weigh 1g.

Therefore, the anisotropic porous membrane of the present invention is suitable for use in final filters, pharmaceutical filters, etc. to remove microorganisms and foreign substances from pharmaceuticals, and the manufacturing method of Rikki's invention is suitable for use in these applications. It is possible to provide an orthogonal porous membrane.

[Brief explanation of the drawing]

Figures 1(a) to 1(C) show the '
! It is a J diagram showing the manufacturing steps of an example according to the J manufacturing method,
FIG. 2 is a diagram showing how a final filter for infusion using an embodiment of the anisotropic porous membrane of the present invention is used, and FIG. Example G]
FIGS. 4(a) to 4(C) are electron micrographs of an example of the anisotropic porous membrane of the present invention;
．． : Figures 5(a) and 5(b) are electron micrographs of conventional porous membranes. DESCRIPTION OF SYMBOLS 1... Substrate, 2... 779IIN layer, 3... Polymer solution, 5... Support layer, 6... Anisotropic porous membrane. Patent applicant -i Rumo Co., Ltd. Agent
Person Patent Attorney 8 1) Mikio (a) ゛ 1 l Figure 3 Figure 2 Figure 4 (a) Figure 4 (b) Figure 4 (C) Figure 5 (a) Figure 5 (b) ) Figure Procedure Amendment Teeth October 3, 1980 Manabu Shiga, Commissioner of the Patent Office1, Indication of the Case 1981 Patent Application No. 141.4982, Title of Invention Porous Membrane and Process for Producing the Same3, Amendment Relation to the case involving the person who filed the patent application Address of the patent applicant: 2-44-1 Hatagaya, Shibuya-ku, Tokyo
Title: Terumo Corporation Representative Director Mitsuo Tozawa 4, Agent 7, amend the detailed statement of amendment as follows. (1) “Ko/” written on page 26, lines 16 to 17
is corrected to "ko/2". (2) [GhiWPJ, rGV
Corrected to WPJ. (3) Table 2 on page 31 is corrected as follows. Second surface porosity Water permeability Bubble cut rate point (%) (ml/l1lin (kg/cm2)
(%)・cm2)

Claims (12)

[Claims] (1) consisting of a porous thin film layer of a polymer and a porous support film made of a homogeneous polymer having a good solvent in common with the polymer and coated on at least one side of the thin film layer;
The pores in the porous thin film layer are pores eroded by a good solvent common to the polymer of the thin film layer and the polymer of the support film layer that were contained in the pores of the porous support film, and An anisotropic porous membrane having through-holes formed by communicating the pores with the pores of the support layer, and wherein the good solvent is completely removed. (2) The anisotropic porous membrane according to claim 1, wherein the polymer forming the porous thin film layer and the porous support membrane is polyvinylidene fluoride. (3) The thickness of the anisotropic porous membrane is 50 to 200 μm, and the layer thickness ratio of the thin film layer to the supporting film layer is 1:500 to 1:20.
000, the anisotropic porous membrane according to claim 1 or 2. (4) The anisotropic porous membrane according to claim 3, wherein the thin film layer has an average pore diameter of 0.01 to 0.6 μm and the support layer surface has an average pore diameter of 0.1 to 2.0 μm. . (5) Form a thin polymer film layer on the substrate in advance, then cast a polymer solution of the same polymer as the above polymer dissolved in a good solvent onto this thin film layer, evaporate a part of the solvent, and then A method for producing an anisotropic porous membrane by immersing it in a solvent or non-solvent and drying it. (6) Form a thin film layer of polyvinylidene fluoride on the substrate in advance, then cast a polymer solution of polyvinylidene fluoride dissolved in a good solvent onto this thin film layer, evaporate part of the solvent, and then The method for producing an anisotropic porous membrane according to claim 5, which comprises immersing the membrane in a non-solvent and drying the membrane. (7) The method for producing an anisotropic porous membrane according to claim 5 or 6, wherein the thin film layer is obtained by spraying a polymer solution onto the substrate. (8) The method for producing an anisotropic porous membrane according to claim 5 or 6, wherein the good solvent is a mixture of a quick-drying good solvent and a slow-drying good solvent. (9) The weight ratio of quick-drying good solvent to slow-drying good solvent is 5
The method for producing an anisotropic porous membrane according to claim 8, wherein the ratio is 0:50 to 95:5. (10) The method for producing an anisotropic porous membrane according to claim 5 or 6, wherein the polymer concentration of the polymer solution cast onto the thin film layer is 15 to 25% by weight. (11) The method for producing an anisotropic porous membrane according to claim 7, wherein the polymer concentration of the polymer solution sprayed onto the substrate is 0.001 to 1% by weight. (12) The good solvent for the polyvinylidene fluoride polymer solution to be cast onto the thin film consists of a quick-drying solvent selected from the group consisting of acetone, methyl ethyl ethyl ketone, and tetrahydrofuran, and dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. 7. The method for producing an anisotropic porous membrane according to claim 6, wherein the mixed solvent is a slow-drying solvent selected from the group consisting of a slow-drying solvent.