JPS6252185A - Manufacture of porous ceramic membrane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing porous ceramic membranes. More specifically, the present invention relates to a method for manufacturing a porous ceramic membrane that allows control of the microstructure of the porous membrane and facilitates its manufacture.

[Conventional technology]

Porous ceramic membranes have traditionally been formed using a molding method, but with the molding method, it is difficult to make thin and multilayered films, it is impossible to form asymmetrically structured membranes or large molded products, and expensive molds are required. There were disadvantages such as low production productivity and the need for press machines.

Other methods, such as the doctor blade method, which are alternatives to the mold forming method, have low strength of the formed film, making it difficult to form a thin film, making the molded product difficult to handle, lacking flexibility, making multilayers difficult, not being able to form an asymmetrical structure, and forming a molded body. The injection molding method also has drawbacks such as complicated and large-scale machinery and high costs.

[Problem that the invention seeks to solve]

As a result of various studies in search of a method for manufacturing porous ceramic membranes that eliminates the drawbacks of these conventional methods, makes it possible to control the microstructure of the porous membrane, and facilitates its production,
The present inventors have now discovered that a method of firing a ceramic powder composite film obtained by dry-wet film formation using a polymeric substance as a binder can effectively solve the above problems. Ta.

[Means for Solving the Problem] and [Operation] Therefore, the present invention relates to a method for producing a porous ceramic membrane, and the production of the porous ceramic membrane involves adding ceramic powder to a solution of a polymeric substance in an organic solvent. This is carried out by dry-wet spinning the filled stock solution and firing the resulting composite membrane. The porous ceramic membrane produced by such a method may have any shape such as a hollow fiber shape or a flat membrane shape.

An organic solvent solution of a polymer substance that is highly filled with ceramic powder is formed, for example, by the following combination.

Contribution to one polymer - - - 11-modal polysulfone Dimethylacetamide, dimethylformamide Polyether sulfone Diethylacetamide, diethylformamide.

N-methylpyrrolidone, morpholine, triethylphosphate polyacrylonitrile dimethylacetamide, dimethylformamide aromatic polyamide diethylacetamide, diethylformamide polyvinyl chloride
Dimethylacetamide, dimethylformamide, diethylacetamide, diethylformamide, N-methylpyrrolidone, acetone polyvinylidene fluoride dimethylacetamide, dimethylformamide, triethyl phosphate cellulose acetate dimethylacetamide, dimethylformamide, acetone For example, the ceramic powder to be filled has a particle size of about 0.00.
AQ201, Y2O crushed to about 1-100 μm
At least one of 3, MgO, 5in2, Si, N4, etc. is used. The filling of these ceramic powders is
Generally, by adding about 20 to 50% by volume of ceramic powder based on the total volume of the polymeric substance and ceramics to an organic solvent solution of a polymeric substance prepared to a concentration of about 5 to 20% by weight. Done.

There, a stock solution for dry-wet film formation is prepared.

Dry-wet membrane formation of the stock solution prepared in this way is carried out according to the usual method, but depending on whether the structure of the composite membrane formed is symmetrical or asymmetrical, it is possible to form a coagulable liquid. The way people contact each other will change.

That is, a composite film with a symmetrical structure can be obtained by contacting both sides of a membrane-formed body produced by a wet-dry process with a coagulable liquid, and a composite membrane with an asymmetric structure can be obtained by bringing one side of the membrane-like body into contact with a coagulable liquid. A film can now be obtained.

Specifically, when forming a membrane into a hollow fiber, a core liquid such as coagulating water from the spinning dope is simultaneously extruded from the center of a double annular nozzle, and a certain spatial distance is maintained from the tip of the nozzle. When the hollow membrane is introduced into a gelling bath (water), gelation proceeds from both sides of the hollow membrane, and a composite membrane with a symmetrical structure is formed there. On the other hand, when a core liquid such as kerosene, which is non-coagulating from the spinning dope, is simultaneously extruded and introduced into a gelling bath, gelation proceeds from the outer surface of the hollow membrane, forming a composite membrane with an asymmetric structure there.

In addition, when forming a film into a flat film, after casting the stock solution on any substrate such as a glass plate or plastic sheet,
When the substrate is immersed in a gelling bath, gelation of the membrane proceeds from the side not in contact with the substrate, forming a composite membrane with an asymmetric structure. Further, when the stock solution is passed through a slit to form a flat membrane-like body and this is directly introduced into a gelling bath, gelation proceeds from both sides of the flat membrane, forming a composite membrane with a symmetrical structure there.

The composite films of various shapes thus formed are then fired. Firing is performed by once forcing the composite film at a temperature of about 500 to 9000C, and then heating it in an electric furnace to a temperature of about 1400 to 1900C for about 0.5 to 10 hours. When the composite membrane is fired in this way, pores with a pore diameter of about 1 μm are formed in the case of a hollow membrane, and pores with a pore diameter of about 1 μm are formed in the case of a flat membrane. Porous ceramic membranes each having a gap of about IX1 μm are obtained.

〔Effect of the invention〕

According to the present invention, the stock solution used for dry-wet film formation has good fluidity, so it is not only easy to make thin films, multilayers, and tubes, but also has high productivity because the gelation speed is high. By performing this from both sides or one side of the membrane, a membrane-like body having a symmetrical or asymmetrical structure can be obtained as desired.

The composite membrane obtained in this way has high membrane strength, is flexible, and is easy to handle, so secondary processing is easy, and by firing it, a porous film with a controllable porous microstructure and shape Ceramic membranes can be easily produced.

〔Example〕

Next, the present invention will be explained with reference to examples.

Example 1 Polysulfone (UCC product P-1700) 20 g
, A Q 203 fine powder (particle size o, oos μm) 40
A spinning stock solution consisting of a mixture of
Using a No. 111 double annular nozzle, dry-wet spinning was performed according to the spinning conditions below, and the inner diameter was about 0.5 mm and the outer diameter was about 1.2 mm.
A composite hollow fiber was obtained.

Core liquid (water) flow rate 5 m Q/min Stock liquid flow rate 20 m Q/min Nozzle discharge low gelling bath distance 50 Gelling bath (water) temperature 10°C Winding speed
The composite hollow fiber obtained at 16.8 m/min was heated at 900°C for 5
After time firing, when fired at 1700°C for 2 hours, the inner diameter was 0.
A porous ceramic hollow membrane with a diameter of 25 mm and an outer diameter of 0.5 mm was obtained.

This porous ceramic hollow membrane has a symmetrical cross-section,
A relatively dense skin layer is formed on both the outside and inside of the hollow membrane, and the pore size distribution of the skin layer is almost uniform.

Example 2 The stock solution used in Example 1 was cast onto a glass plate, and the glass plate was immersed in a gelling bath (water) for about 10 minutes, followed by washing with water and drying at 50°C for an additional 24 hours. I did it. When the composite membrane peeled off from the glass plate was baked at 1550°C for 2 hours, the cross section showed an asymmetrical structure, with the surface in contact with the glass plate having a sponge layer with large pores, and the opposite side having a relatively dense layer. A porous ceramic flat membrane was obtained in which a skin layer was formed and the skin layer had a substantially uniform pore size distribution.

Claims (1)

[Scope of Claims] 1. Production of a porous ceramic membrane, characterized by forming a wet-dry membrane from a raw solution of a high-molecular substance solution in an organic solvent filled with ceramic powder, and firing the resulting composite membrane. Law. 2. The method for producing a porous ceramic membrane according to claim 1, wherein a composite membrane with a symmetrical structure obtained by contacting both sides of a membrane-like body produced by a wet-dry process with a solidifying liquid is used. 3. The method for producing a porous ceramic membrane according to claim 2, wherein a composite membrane obtained by introducing a hollow fiber-like body extruded from a spinning dope coagulating core liquid simultaneously into a gelling bath is used. 4. The method for producing a porous ceramic membrane according to claim 2, wherein a composite membrane obtained by directly guiding a flat membrane-like body passed through a slit into a gelling bath is used. 5. The method for producing a porous ceramic membrane according to claim 1, wherein a composite membrane with an asymmetric structure obtained by contacting one side of a membrane-like body produced by a wet-dry process with a solidifying liquid is used. 6. The method for producing a porous ceramic membrane according to claim 5, wherein a composite membrane obtained by introducing a flat membrane-like body formed by casting onto a substrate into a gelling bath is used. 7. The method for producing a porous ceramic membrane according to claim 5, wherein a composite membrane obtained by introducing a hollow fiber-like body extruded from a spinning stock solution and a non-coagulable core liquid at the same time into a gelling bath is used. 8. The method for producing a porous ceramic membrane according to claim 1, wherein the firing is performed at a temperature of about 1400 to 1900°C.