JPS6075320A - Permeselective composite membrane for gas and its preparation - Google Patents

Abstract

PURPOSE:To improve heat resistance, chemical resistance and mechanical strength of the title membrane by laminating a thin film with surface layer comprising a siloxane compd. treated with plasma of non-polymerizable gas on a high molecular porous base body. CONSTITUTION:A thin film having a surface layer comprising a cyclohexane cpd. treated with plasma of non-polymerizable gas such as hydrogen, carbon monoxide, nitrogen, or inert gas is laminated on a high molecular porous base body such as tetrafluoroethylene resin. Then, the film is placed under glow discharge in the atmosphere of polymerizable gas under reduced pressure to deposit plasma polymerized film on the thin film of cyclohexane compd. which has been treated with plasma.

Description

Detailed Description of the Invention 1 Technical Field 1 The present invention relates to a gas selectively permeable composite membrane and a method for producing the same, and more particularly, to a porous polymeric support.
Plasma tariff 1 whose surface layer is made of non-polymerized 1-1 gas
A thin film made of a siloxane compound is deposited, and then the siloxane compound is deposited. The present invention relates to a gas selectively permeable composite membrane in which a plasma polymerized membrane is deposited on WIIS'=-l: and a method for manufacturing the same.

[Disadvantages of the Invention 1 In recent years, separation and purification of gas mixtures using gas selectively permeable membranes has been actively investigated. 1ull, selectively permeates oxygen over air to produce oxygen' Synthetic gas obtained by using coal, natural gas, oil sands, etc. as raw materials for steam reforming, thermal decomposition, etc.
Or in steel plants, etc. (by selectively permeating hydrogen from waste gas from coke ovens, separating and refining it from carbon oxide and methane pipe gas, and using these gases as starting materials to produce methane/-) Attempts to use basic chemicals such as ethanol, and even recovery of helium by selective permeation from natural gas':
There is a difference. The characteristics required for gas selectively permeable membranes that are expected to be used in these applications are that they have good gas selectivity and gas permeability, as well as heat resistance, chemical resistance, and high strength.

Force selectivity is expressed as the ratio of the permeation rate of a specific gas to other gases, and if the gas selectivity is excellent, it means that the gas separation ability is excellent. Gas permeability is expressed in terms of gas permeation rate, and a high gas permeability means that more gas can pass through the membrane. Furthermore, considering the temperature, type, and force pressure of the gas mixture to be separated, the force-selective gland must have heat resistance, chemical resistance, and high strength.

However, all of these required characteristics are +14 with the 11′L-Soji made of high molecular weight polymer or Kyoriki, which has been set as 1 υ.
It is impossible to rub. Therefore, various methods have been currently being investigated in order to reduce the monthly interest rate based on these required characteristics. As an example, using phase separation,
A method using a non-λ-symmetric membrane with the active skin layer on the surface as thin as possible, or a method in which an ultra-thin membrane corresponding to the active skin layer is manufactured independently and composited onto a porous support. and so on. However, none of these methods has succeeded in producing a film that achieves all of the above-mentioned required characteristics in 1 minute.

The present invention satisfactorily satisfies the above-mentioned required characteristics compared to conventional membranes.
The present invention provides a gas selectively permeable membrane having high performance as compared to J7, and a method for manufacturing the same.

[Configuration 1 of the Invention The gas selectively permeable membrane of the present invention is a porous polymer support in the form of a film or a tube, the surface layer of which is laminated with a thin film of a siloxane compound that has been plasma-treated with a non-polymerizable gas. Furthermore, it is a composite film having a structure in which a plasma polymerized film is deposited on the film. In this composite membrane, the porous support has +, 17. It plays a role in maintaining the mechanical strength of the composite membrane (J also -).

The siloxane compound thin film closes the pores of the porous support,
At the same time, its surface layer is plasma-treated using a non-polymerizable force to form an advanced frame 1i! It has a 'li II'r structure and also has a certain gas selective permeation function. In addition, the plasma polymerized film in the top layer has a dense crosslinked and branched structure and has a higher power selective permeation function.

The present inventors have developed a gas selectively permeable composite membrane in which a plasma polymerized membrane made of various monomers is deposited on a polymeric support. In particular, when a support layered with a siloxane compound is used, the extremely high gas permeability and elastic structure of the siloxane compound can be used, and when a plasma polymerized film is deposited on this support, a useful force-selective permselectivity film can be obtained. It has been found that the synapse can be reduced by 1:). However, siloxane compound thin film-1
- If a plasma polymerized film is immediately deposited on -? The gas selective permeability performance of the composite membrane was unstable and often varied. As a result of further thorough examination regarding this problem, we first performed plasma treatment with a non-polymerizable gas on the surface of the siloxane compound thin film, and then performed plasma polymerization.
The present inventors have discovered that a gas-selective permeable composite membrane with stable performance and further improved selective function can be obtained by doing so, and have completed the present invention.

The polymeric porous support used has uniform pore size, high porosity, and excellent heat resistance, chemical resistance, and strength properties.
It is desirable to have one. Since the size of the pores affects the thickness of the film of the silohesane compound to be coated, it is advantageous to have a smaller pore size, and preferably 1.5 mm or larger than 171111 mm. 1 and t are amazing; when it gets low to the edge, gas permeability becomes steep:/
, j′i, ni]・desirably more than 30%.
It is necessary. As the material A, polyvinyl alcohol, vinyl chloride, polypropylene, polyacrylate, polysulfone, polyimide, polycarbonate, etc. are useful because of their strength, and tetrafluoroethylene is used as a material with excellent heat resistance and chemical resistance. It can be said that resin is suitable.

1. A thin film made of a siloxane compound is laminated on the support. Siloxane compounds are polymeric abrasives with the best gas permeability. Polydimethylsiloxane, polymethylvinylsiloxane, polymethyl 70rosiloxane, polymethylphenylsiloxane, or boridimethylsiloxane-carbon one-block copolymer. Examples include screen polymers and typical combinations. Among the above-mentioned siloxane compounds, it has been found that silohesane compounds containing an aromatic ring in the molecular chain, such as the latter two, are particularly suitable for the plasma treatment described below. The method of laminating these siloxane compounds is to prepare a solution by adding and mixing the siloxane compound, a solvent for dissolving it, and a vulcanizing agent if necessary, and dipping the support into the solution. After applying the coating using a knife or roll, dry and volatilize the solvent, and if necessary, heat and vulcanize. The siloxane compound thin film laminated in this way closes the pores of the support, and the thickness of the siloxane compound thin film 1! It will have l. The film thickness varies depending on the pore size of the support and the required strength, and is controlled by the solution concentration, coating thickness, etc.

Next, the surface of the laminated silicon compound is subjected to plasma treatment for 11". Plasma treatment is performed by glow discharge under reduced pressure and active species such as lanocal, electrons, ions, excited species, or ultraviolet rays. It uses light energy to modify the surface of an object primarily through chemical action. That is, compared to sputtering, etching, etc., the reaction is slow, and only the crosslinking reaction on the surface proceeds.

The effects of the plasma treatment in the present invention can also be considered as follows. One is that low-molecular compounds such as moisture attached to the surface of the siloxane compound are removed from the surface by reaction with the active Tm in the plasma, improving the reproducibility of the next plasma polymerization reaction, and also improving the reproducibility of the polymerized film. The aim is to strengthen the adhesion with the Another reason (1-) is that since the surface of the siloxane compound is highly cross-linked, a certain degree of selective gas permeability is developed only in this area. Plasma treatment is performed using an 11-polymer gas. That is, an inert force such as argon, aluminum, neon, etc.
can include hydrogen, nitrogen, -carbon oxide, etc.

On the other hand, depending on the processing conditions, oxygen may be the main ti'i
This results in a strong etching effect and the effect is not sufficient.

Discharge conditions vary depending on the device, but usually the power is 5 ()
~200 W, time 2-20 min, pressure (+, f-15
The desired effect can be achieved by operating within the range of ~5, OLorr. Furthermore, siloxane compounds have poor stability against radiation compared to general organic rubbers, but when they contain an aromatic ring, their radiation resistance is significantly improved. Therefore, it has been found that the effect of plasma treatment is more strongly expressed when a siloxane compound containing an aromatic or (r ring) is used.

Next, a plasma polymerized film is deposited on the plasma-treated siloxane compound thin film. Plasma polymerization (coordination) is preferably carried out immediately following plasma treatment.This is because once the plasma-treated samples are taken out in an air atmosphere, moisture and other residues are removed again. This is because 1 out of 1 free radicals outweighs 9 out of 1. Ino: The majority of hole monomers are capable of plasma polymerization, resulting in homogeneous pinhole formation, pole & 7 coatings (
11 1,'I□There are signs. In particular, silane compounds containing a triple bond or triple bond unsaturated groups have a high reactivity of -1(4) and have a branched or cross-linked structure. In the case of silane compounds containing phenyl groups, polymers with many phenyl groups in the side chains are formed.
The present inventors have discovered that all of them provide excellent gas selective permeability membranes. Specific examples include trimethylvinylsilane, dimethylnovinylsilane, methyltrivinylsilane, tetravinylsilane, trimethylvinylchlorosilane, allyl I.limethylsilane, ethynyltrimethylsilane, methylphenylsilane, and trimethylphenylsilane. The plasma polymerization operation is started by returning the inside of the reaction vessel to high vacuum again while leaving the plasma-treated sample in the reaction vessel, and then introducing monomers. I
'f: Out of production varies depending on the device, generally the output is 5
-100W, time 3-60 minutes, pressure (,), (15
It operates in the range of ~5.0 Lorr. If the output is too low, the polymer will have a low crosslinking density, and if the output is too high, it will emit 1 minute of light from the small assembly, which is not unpleasant, and the yarn +'
For station i, the operating range as shown in L is preferable. Since the time is proportional to the polymerized film thickness, if the strip 1!1 of the plate is constant, it becomes a parameter for adjusting the film thickness to a predetermined value. Pressure also varies depending on pumping speed and monomer flow rate, type of monomer in the pond, and discharge conditions, but operation at lower pressures tends to slow deposition rates. In any case, it is desirable to adjust the polymer film thickness to 2 μIl+ or less.

This is because the plasma polymerized film has a high degree of crosslinking and branching (14
This is because it has excellent heat resistance and chemical resistance due to its structure, but on the other hand, if it is deposited thickly, defects such as cracks are likely to occur due to the strong internal stress.

The present invention will be specifically explained below with reference to examples.

Note that the gas permeation rate and selection 1/1 shown in the example. was determined using one method (pressure method) for AST, and the permeated components were separated, detected, and quantified using a gas chromatograph.The measurement temperature was 100°C in all cases. For the permeation rate of each force in the medium, Q is used.For example, the permeation rate of oxygen is Q.7, nitrogen is QN2, hydrogen beam II,...
- Carbon oxide is designated as 'CO.

The unit is CIll 3/hat) 12...X(・gu・cml1)
It is 8. In addition, selectivity is determined by the ratio of iλ past i1 degrees of each gas.
and selectivity α between oxygen and nitrogen. 1, /N, is Q.

/QN, is the value. Furthermore, the plasma film thickness is determined by the 'iJ!' of the sample due to polymerization. 'II't, Measure the specific gravity of the increase and polymerization 14\, and calculate it from there.

Example 1 Feninori. Silicone rubber (manufactured by F-Le Silicone Co., Ltd., S ly: 95!-+ u) containing (2<1', iTj:i) was dissolved in toluene and a vulcanizing agent was added.
'14. %18 liquid was prepared. Using a doctor knife, add this solution to a polytetrafluoroethylene + 44-lipid porous membrane (manufactured by Sumitomo Electric Industries, Ltd., manufactured by Sumitomo Electric Industries, Ltd.,
After footing at 0 Roporel"r'-(122)l:, second vulcanization was performed at I'7 (1'C) for 10 minutes, and then two-person vulcanization was performed at 20 (1'C) for 4 hours. This was crosslinked and cured to form a siloxane compound thin film with a thickness of 25 μm.The gas selective permeability of the obtained laminated film was as follows.

Q02=1. ]
・1 a+1. /CO" 3.1 Using this laminated film, when only plasma treatment (operation 1) is performed, when only plasma polymerization (operation 2) is performed, and when plasma treatment and plasma polymerization (operation? () are performed) 11j at the time of each 141 work.
The properties of the obtained membranes are summarized in Table 1.

(Operation 1) Place the laminated film in a Pelger type plasma device and set the device to Q.
, t) After reducing the pressure to OI Lorr, supply argon gas, operating pressure 0.3 Lorr, power 3 fl
Plasma treatment was performed for 5 minutes under flW conditions.

(1 presentation 1'+: 2)
After reducing the pressure to +1 Lorr, methyltrivinylsilane was supplied at 5+nl/mi1+, operating pressure 0,2!
-) torr, a power of 2 ()W, and a reaction time of 20 minutes.

The obtained polymer film had a thickness of (1.27 μm).

(Operation 3) After performing the same operation as Operation 1, stop the supply of argon gas, reduce the pressure inside the apparatus to 0.001 Lorr, and then add methyltrivinylsilane to 5 +nl/m.
Supplied in batches, operating pressure +1.251. orr, power 20
W, polymerization operation with reaction time of 20 minutes? The thickness of the polymerized film obtained was f', l, 26 μm11.

As shown in this figure, it can be seen that by performing plasma treatment and subsequent plasma polymerization, a composite membrane having the most selective gas permeation function can be produced.

Examples 2 to j3 Polydimethylsiloxane-carbonate block copolymer (sold by Chisso) was dissolved in methylene chloride;
A weight W+,% solution was prepared. Using a 1 ton knife, apply this solution to 70 Robo 7FT”022 in the same manner as in Example 1.
After coating the second layer, the solvent was evaporated in an atmosphere of 50° C., and a thin film having a thickness of 11 μl+ was laminated. The laminated film prepared by 1:j is installed in a plasma device, and the system is heated to
f, l, 11. After reducing the pressure to orr, hydrogen gas was supplied to 0 (supply, IM ft free force fl, 21.orr, power 10
(1) Plasma treatment was carried out for 3 minutes on row 1'1 of W. Next, the hydrogen supply was stopped. As shown in Table 2, various silane monomers were supplied and plasma polymerization was performed.
It had excellent gas selective permeability.

[Effects of the Invention] The force-selective permselective composite membrane of the present invention combines a force-permeable siloxane compound with a polymer support that has excellent heat resistance, chemical resistance, and chemical strength. Thin films are laminated, and the surface layer of the thin film is plasma treated to form a highly cross-linked structure, and then a plasma polymerized film is deposited on top of this to form a composite film structure.This plasma treatment and plasma polymerization The combination results in a composite membrane that not only has extremely poor gas selective permeability, but also has heat resistance, chemical resistance, and high strength.

Claims (10)

[Claims] (1) A polymer-porous support, the surface layer of which is a non-polymerizable gas, a thin film made of a plasma-treated siloxane compound, and a plasma-polymerized film. A gas selectively permeable composite membrane characterized in that it is crucible. (2) Special N'llN! characterized in that the siloquiline compound is a polymer or copolymer containing an aromatic ring! Composite membrane according to claim 1. (3) the surface layer of a thin film made of a silohezane compound or hydrogen;
- A composite membrane according to claim 1, characterized in that it has been treated with plasma using any one of carbon oxide, nitrogen JJ, and an inert gas, or a mixture thereof. (4) 1.1 that an organosilane compound containing at least 1-11 U double bonds or triple bonds or phenyl groups is deposited by plasma polymerization by glow discharge;
Characteristic Features 11'1 Scope of Interest 1st JRJ I Some Composite Films. (5) The composite membrane according to claim 1, wherein the polymeric porous support is made of tetrafluoroethylene resin. (6) After applying a solution containing a siloxane compound to a porous support and drying or heating it, a thin film of the siloxane compound is laminated on the porous support. ') 1. (1
The surface layer of the siloxane compound thin film is plasma treated and then subjected to glow discharge in a polymerizable gas atmosphere under a reduced pressure of not more than 5 Lorr. 1. A method for producing a gas selectively permeable composite membrane, comprising: depositing a plasma polymerized membrane on the plasma-treated siloxane compound thin film I described in -1- below. (7) Claim 6 of Part 8'1, characterized in that the siloxane compound is a polymer or copolymer containing an aromatic ring.
Manufacturing method described in section. (8) A special feature characterized in that the non-polymerizable gas is hydrogen, carbon oxide, nitrogen or an inert gas, or a mixture thereof! '1ltl'1 range f56 manufacturing method. (9) The polymerizable gas is an orga/silane compound containing at least one double bond, single bond, or phenyl group.
& manufacturing method. (10) Features 1 and 11 include the use of a porous material in the form of a polymer with % pores (+1 made of tetrafluoroethylene IAI resin as a support) or in the form of a film. The manufacturing method described in Section 6.