JPS6025507A - Gas permselective composite membrane and preparation thereof - Google Patents

Abstract

PURPOSE:To prepare a composite membrane having gas permselectivity, by forming an organosilane polymer membrane containing a phenyl group to the surface of a high-molecular support by plasma polymerization under glow discharge. CONSTITUTION:A high-molecular support is set to a plasma polymerization apparatus so as to be placed on an electrode 9 or between electrodes 8, 9 and a reaction vessel 7 is evacuated by a vacuum pump 6. A silane compound containing a phenyl group is supplied into the reaction vessel while the flow amount thereof is regulated by a mass flow meter 2 and power is applied to initiate glow discharge. After a necessary plasma polymerization membrane is accumulated on the high-molecular support, polymerization is completed. The membrane is grown without excessively decomposing the phenyl group because silicon is present in the silane compound containing the phenyl group and a polymer having a large number of phenyl groups in the side chain thereof is formed and a membrane excellent in gas permselectivity is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a gas selectively permeable composite membrane and a method for producing the same, and more particularly, the present invention relates to a gas selectively permeable composite membrane and a method for producing the same, and more particularly, the present invention relates to a gas selectively permeable composite membrane and a method for producing the same.
The present invention relates to a gas-selective permselective composite membrane in which an organosilane compound containing a group t is deposited by plasma polymerization, and a method for producing the same.

[Background of the Invention] In recent years, separation and purification of gas mixtures using gas selective permeability cycles has been actively studied. In other words, oxygen rather than air]
Attempts are being made to obtain oxygen-enriched air by selectively permeating it and using it for medical purposes and combustion systems, as well as coal, natural gas,
Hydrogen is selectively permeated from synthesis gas obtained by steam reforming, thermal decomposition, etc. using oil V sand as a raw material, or from waste gas from coke ovens at steel plants, etc.
- Attempts have been made to separate and purify gases such as carbon oxide and methane and use these gases as starting materials to produce basic chemicals such as methanol and ethanol, and there have also been attempts to recover helium from natural gas by selective permeation. The characteristics required for gas selectively permeable membranes expected for these applications are high gas selectivity and gas permeability, as well as heat resistance, chemical resistance, and high strength.

Gas selectivity is expressed as the ratio of reaction rates between a specific gas and other gases, and a high gas selectivity means nothing else but an excellent gas δ separation ability. Gas permeability is expressed by the gas permeation rate, and a high gas permeability means that a large amount of gas permeates through the membrane. Furthermore, in consideration of the temperature, type, and gas pressure of the gas mixture to be separated, the gas selectively permeable membrane must have heat resistance, chemical resistance, and high strength.

However, it is impossible to satisfy all of these required properties with a single commercially available polymer or copolymer material. Therefore, various methods have been studied to date to obtain materials that satisfy these required characteristics. For example, a method using an asymmetric membrane with an active skin layer on the surface as thin as possible by utilizing phase separation, or a method in which an ultra-thin membrane corresponding to the active skin layer is independently manufactured and used on other porous supports.
＼There are ways to try to combine them. however,
None of these methods has succeeded in obtaining a film that fully satisfies all of the above-mentioned required characteristics.

The present invention provides a gas-selective permselective membrane having high performance that fully satisfies the above-mentioned required characteristics compared to conventional membranes, and a method for manufacturing the same.

[Structure of the invention]

The gas selectively permeable membrane of the present invention is characterized by comprising a film-like or tubular polymer support and an organosilane polymer thin film containing phenyl groups that are plasma-polymerized by glow discharge on the surface of the support. In this composite membrane, the plasma polymer thin film is the part that has a substantial gas selective permeation function, and the polymer support mainly only provides mechanical strength to the composite membrane.

The polymer support may be a homogeneous membrane with no porous parts, but to obtain a membrane with higher gas permeability, a porous membrane or thin polymer membranes are laminated to close the surface pores of the porous membrane. A composite membrane with a similar shape is preferable.

When using a porous membrane, it is desirable that the average pore diameter is 0.1 micron or less when directly depositing a plasma polymerized thin film. The reason for this depends exclusively on the strength of the plasma polymerized thin film deposited on the surface of the porous support. As will be described in detail later, if the film is deposited so thickly that it blocks pores exceeding 0.1 μm, defects such as cracks will occur due to internal stress, and the function as a gas selectively permeable membrane will deteriorate. Therefore, 0.1
When using a porous membrane with an average pore diameter exceeding μ as a support, it is desirable to have a structure in which a plasma polymerized membrane is deposited on a thin membrane laminated with a thin polymer membrane with excellent gas permeability on its surface. ! Yes.

Various polymers can be used as the polymer support depending on the use of the gas selectively permeable membrane, but it is first required to have excellent chemical resistance. Furthermore, since good mechanical properties and heat resistance are also advantageous, polysulfone, polyimide, etc. are preferable. However, tetrafluoroethylene resin is a polymer material with the most excellent properties in these respects, and the technology for making it porous has been advanced, so it can be used favorably as a porous polymer support.

When using a porous membrane with an average pore diameter exceeding 0.1μ, the material for the thin film to be laminated to close the pores in the surface layer should be a material with excellent gas permeability or thin film formation in addition to the above properties. Highly functional polymeric materials are desirable, such as siloxane polymers or copolymers such as polydimethylsiloxane, polyphenylsiloxane, polyvinylsiloxane, polydimethylsiloxane-carbonate block copolymers, or polyphenylene oxide, polysulfone,
Representative examples include resins such as polyimide and polyaromatic ester. Several techniques are known for forming these thin films on the surface of porous membranes and for laminating these thin films on porous membranes. Examples include a method in which a polymer solution is spread on the surface of a liquid such as water and transferred onto a porous membrane, or a method in which a polymer solution is coated on a porous membrane using a roll coater, reverse roll coater, etc. Any of these techniques may be applied.

On the polymer support obtained in this way, -j, an ultra-thin film of a plasma polymer that exhibits a substantial gas permeation function, is deposited.

],゛.

In this method, when the polymer is introduced in the form of vapor into the system and an electric field is applied to create a plasma state, the polymerizable organic monomer is activated and becomes radicals or ions, which sequentially combine to increase the molecular weight. The vast majority of organic polymers can be polymerized in this manner. Its features include the ability to obtain a homogeneous, pinhole-free, ultra-thin coating;
This means that the molecular structure of the polymer is rich in branched structures and crosslinked structures.

Among the various organic polymers, silane compounds tend to form good quality plasma polymers.゛As a result of detailed studies on plasma polymerization conversion of various organosilane compounds, the present inventors discovered that silane compounds containing phenyl groups exhibit excellent gas selective permeability, and completed the invention. .

Polymers containing phenyl groups are generally characterized by high gas selectivity and excellent heat resistance.

However, when an aromatic compound that does not contain silicon is subjected to plasma polymerization, the reaction proceeds with the cleavage of phenyl groups, so the resulting plasma-polymerized polymer has a structure that does not contain much phenyl groups. On the other hand, the plasma-polymerized membrane with a 11'-1 ratio, combined with its crosslinked structure, becomes a membrane with excellent selective permselectivity.

! 1. Specific examples of the silane compound containing a phenyl group include phenylsilane, methylphenylsilane, dimethylphenylsilane, phenyltrimethylsilane, chlorophenylsilane, and dimethylphenylvinylsilane. Silane compounds whose boiling point exceeds 200℃ are
This is not preferable because it makes it difficult to supply uniformly to the reaction vessel.

Next, a method for conducting plasma polymerization using these phenyl group-containing silane compounds will be described.

(1) Set the polymer support in a plasma polymerization apparatus.

FIG. 1 shows a schematic diagram of the polymerization apparatus used in this example. A polymeric support is placed on electrode 9 or between electrodes 8 and 9.

(2) The inside of the reaction vessel 7 is vacuum pumped to 0. o1to
Reduce the pressure to below rr.

(3) Under reduced pressure, the silane compound containing a phenyl group is supplied into the reaction vessel while adjusting the flow rate using the mass flow meter 2. At this time, an inert gas such as helium or argon may be used as a carrier gas. Further, the pressure inside the reaction vessel is 5 torr or less, preferably l [orr
Keep below.

Although the optimum value differs depending on the equipment and other operating conditions, it is necessary to avoid giving too much as this will cause deterioration of the polymer support.

(5) Glow discharge is continued for a predetermined period of time, and after the necessary plasma polymerized thin film is deposited on the polymer support, the polymerization is terminated. The thickness of the plasma polymerized thin film is preferably 0.01μ or more and 0.5μ or less. If it is thinner than 0゜01μ,
Gas selective permeation function is not fully expressed. On the other hand, 0.5
If it is thicker than μ, it is disadvantageous in terms of gas permeability, and defects such as cracks are likely to occur due to its high-density crosslinked structure.

Next, examples will be shown to specifically explain the invention.

Note that the gas permeation rate and selectivity shown in the examples are as follows:
Based on the STM method (pressure method), the permeated components were separated and detected using a gas chromatograph, and determined by quantitative determination. The measured temperature was calculated from 30-(.

Example 1 -I did.

Using a doctor knife, remove this solution with an average pore size of 0°22μ.
After coating on a polytetrafluoroethylene resin porous membrane (Fluoropore FP-022, manufactured by Sumitomo Electric Industries, Ltd.) having
Secondary vulcanization was performed at C for 4 hours to cure and form a silicone thin film with a thickness of 7 μm.

The gas selective permeability of the obtained composite structure support was as follows.

Oxygen permeation rate QO2 = 2.4X10 i]ec-(z
Hg nitrogen permeation rate'-QN2=1.2X10 G1L/
al-sec-caAJg Water permeability M degree QH2=6.0
×10 c4/d-sec-cxHg-carbon oxide permeation rate QCO-2,4X 10-” cMal・* e c
-cmHg oxygen/nitrogen selectivity ctO3/N2-2.
0 hydrogen/-carbon oxide selectivity αH2/co = 2.5 This support was installed in the plasma polymerization apparatus shown in FIG.

) It was found that the composite membrane had a significantly improved gas selectivity without much decrease in gas permeability.

Q02 = 3.4 x 1O-6ai/cIl-se
c ・craHgQN2 = 5.8 X 1O-7c
d/c+fl-sec ・(3HgQH2= 2.3
X 1O-5d/cll-sec ・(zHgQCO-
5,9×1O-7ci/a11! eC1clllIHg“
02/N2 = 5.9 H2100-39,0 Example 2 27 parts by weight of liquid lubricant (DO8B, manufactured by Shell Chemical Co., Ltd.) was mixed with 100 parts by weight of tetrafluoroethylene resin fine powder (manufactured by Daikin Industries, Ltd., F2O3). This was formed into a plate-shaped product with a medium size of 5 Q mm and a thickness of 5 mm using a ram extruder, and then rolled into a film with a thickness of 0.15 mm. This film was immersed in trichlorethylene to extract and remove the liquid lubricant, and then an ethylene chloride resin film was obtained in an atmosphere at a temperature of 355 to 370°C.

This porous membrane was placed on the electrode 9 of a plasma device, and after reducing the pressure inside the device to 6.01 torr, phenylsilane was added to 7.0 torr. , g/1 ntn was introduced and plasma polymerized to form a polymer thin film on the porous membrane. The reaction conditions were an operating pressure of 0.15 torr, power of 40 W, and reaction time of 30 minutes. At this time, the thickness of the polymer thin film was 0.32μ.

The gas selective permeability of the obtained two-layer composite membrane was as shown below.

QO2 = 5.6 x 1O-6ad/cl -sec
・cm) (gQN2 = 1.8 X 1O-61d
-sec -cmHgQH2= 3.4 x 10 d
/d-sec-cmHgQCO=2.6 x 1
O-6cat/cl -aec -c+nlHgα02
/N2 = 3.1 αH2/Go = 13.1 [Effects of the Invention] The gas selectively permeable composite membrane of the present invention comprises a phenyl group-containing silane with high gas selectivity on a polymer support with excellent mechanical strength. Since it has a composite membrane structure in which a plasma polymerized membrane is deposited from a compound, it is a composite membrane that not only has excellent gas permselectivity but also has heat resistance, chemical resistance, and high strength.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a plasma polymerization apparatus used in Examples. 1...7/mar supply port, 2...mass flow meter, 3...front glass, 4...gasket, 5...
...Vacuum, gauge, 6. Vacuum pump, 7. Reaction vessel, 8.9. Electrode, 10. Matching network, 11. Generator. Patent Applicant: Agency of Industrial Science and Technology, Igawa 1) Yube Procedural Amendment (
Method) 1986//Month, ) - Kazuo Wakasugi, Commissioner of the Japanese Patent Office1, Case description Patent Application No. 132858 of 19822, Title of the invention Gas selectively permeable composite membrane and its manufacturing method 3, Amendment Relationship with the case of a person who does
IO month 25th, I will correct the drawing as shown in the attached sheet0

Claims (8)

[Claims] (1) A gas selectively permeable composite membrane characterized in that an organosilane compound containing a phenyl group is plasma-polymerized by glow discharge and deposited on the surface of a polymer support. (2) Claim 1, characterized in that the organosilane compound is a compound selected from phenylsilane, methylphenylsilane, dimethylphenylsilane, phenyltrimethylsilane, chlorophenylsilane, and dimethylphenylvinylsilane. composite membrane of (3) The composite membrane according to claim 1, wherein the polymer support is a porous material having an average pore diameter of 0.1 μm or less. (4) Claim 1, characterized in that the polymer support is a porous material with an average pore diameter exceeding 0.1μ, and a polymer material that closes chain pores is laminated on the surface of the polymer support. Composite membrane as described in section. (5) Claim 3 or 4, characterized in that the porous polymer support is made of tetrafluoroethylene resin.
Composite membrane as described in section. (6) A gas-selective permeable composite membrane characterized in that an organosilane containing a phenyl group is vaporized in an atmosphere of 5 torr or less, plasma-polymerized under glow discharge, and deposited on the surface of a polymer support. manufacturing method. (7) Claim 6, characterized in that the organosilane compound is a jadz compound of phenylsilane, methylphenylsilane, dimethylphenylsilane, phenyltrimethylsilane, chlorophenylsilane, and dimethylphenylvinylsilane. Manufacturing method described. (8) The manufacturing method according to claim 6, wherein the polymer support is a porous material having an average pore diameter of 0.1 μm or less, and plasma polymerization is directly performed on the surface of the polymer support. (91) After applying a polymer solution to a porous polymer membrane with an average pore size of 0.1μ, the solvent is dried, and if necessary, the polymer is cured and crosslinked to form a thin PIA′f layered polymer. The manufacturing method according to claim 6, characterized in that a support is used. Claim 8, characterized in that α0) the porous polymer support is made of tetrafluoroethylene resin, or The manufacturing method according to item 9.