JPH0357811B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composite molded article for gas separation that has good gas permeability and excellent gas selective separation function, and is particularly suitable for gas separation that is suitable for obtaining a high-concentration oxygen-containing mixed gas from air. The purpose is to provide a composite molded article for use. Currently, selective gas separation technology using polymer thin films is attracting attention as an alternative to the conventional cryogenic liquefaction separation method and adsorption separation method from the viewpoint of energy saving and pollution prevention. Among these, so-called oxygen-enriching membranes, which can obtain a highly concentrated oxygen-containing mixed gas from air, are expected to have many applications such as preservation of perishables, medical use, and combustion-related uses, and their development and commercialization are Waiting. The above-mentioned oxygen enrichment membrane is required to have high oxygen/nitrogen separation ability and high permeation rate (high throughput) as membrane characteristics.
Although relatively high separation performance can be expected in the application of certain types of homogeneous polymer materials that are currently being prototyped, the gas permeation rate is extremely low and it is almost impossible to meet the required characteristics. Furthermore, when using porous materials, a relatively high permeation rate can be expected, but it is quite difficult to obtain a high oxygen/nitrogen separation ability. On the other hand, plasma polymerization technology has recently been studied as a means of obtaining an oxygen-enriched film. That is,
This method involves forming an ultra-thin film with high oxygen/nitrogen separation ability on a suitable support with a relatively high permeation rate, such as a homogeneous thin film support or a porous film support, using plasma polymerization technology. belongs to. As a result of repeated studies from the viewpoint of a support for plasma-polymerized membranes, the present inventors discovered that a monomer compound represented by the formula RC=CSiR ₃ (R in the formula is a monovalent hydrocarbon group) was polymerized. It was previously confirmed that an extremely good oxygen-enriched membrane (a membrane with both high oxygen/nitrogen separation ability and high oxygen permeation rate) can be obtained by combining the resulting polymer thin film with a plasma-polymerized membrane of organic compound gas. However, as a result of various studies aimed at practical application, it was found that the polymerized thin film (support) of the monomer compound described above undergoes compounding when exposed to short-wavelength ultraviolet rays from plasma during the process of forming a plasma-polymerized film. It has been found that the strength of the film as a material deteriorates significantly (its UV resistance is poor), making it difficult to obtain a practical oxygen-enriched film. The present invention solves these problems, and is based on the general formula The monomer compound represented by and the general formula The present invention relates to a composite molded article for gas separation, in which a low-temperature plasma polymerized film of organosilicon compound gas is formed on the surface of a copolymer molded article with a monomer compound shown in the following. Although the homopolymer of the above general formula () has poor ultraviolet resistance, copolymerization with that of the general formula () has the advantage of significantly improving the ultraviolet resistance, and this polymer can be used according to the present invention. The permeation rate of oxygen gas required as a support for the plasma polymerized membrane in the composite molded product is sufficiently high, and compared to the homopolymer of the general formula (), it is easier to mold by casting method etc. It was also confirmed that the quality was excellent. The present invention will be explained in detail below. In the general formulas () and (), R ¹
is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, or a monovalent hydrocarbon group in which the hydrogen atom of these monovalent hydrocarbon groups is partially substituted with a halogen atom, etc. R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are hydrogen atoms, halogen atoms, monovalent hydrocarbon groups having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, Butyl group, vinyl group, allyl group, monovalent hydrocarbon groups in which the hydrogen atoms of these monovalent hydrocarbon groups are partially substituted with halogen atoms, etc., or alkoxy groups having 1 to 8 carbon atoms, such as methoxy group, ethoxy group, propoxy group, and poxy group. Furthermore, A in the formula is an oxygen atom, a divalent hydrocarbon group having 1 to 4 carbon atoms, such as a methylene group, an ethylene group, a propylene group, or represented by the formula -[O-Si(R ⁷ )(R ⁸ )-] _o It is a group that can be used. In the formula, R ⁷ and R ⁸ are monovalent hydrocarbon groups having 1 to 4 carbon atoms, such as methyl group, ethyl group, propyl group, butyl group, vinyl group, allyl group, and hydrogen atoms of these monovalent hydrocarbon groups. is a monovalent hydrocarbon group substituted with a halogen atom etc.,
n is a number from 1 to 3. Examples of desirable monomer compounds corresponding to general formulas () and () are as follows. However, in the following description, Me is a methyl group,
Et each represents an ethyl group. Me-C≡C-Si(Me) ₃ , Et-C≡C-Si
(Me) ₃ , Me-C≡C-Si(Et) ₃ , Me-C≡C-
Si(OMe) ₃ , HC≡C-Si(Me) ₃ , Me-C≡C-
Si(Me) _Cl2 , Me-C≡C-Si(Me) _H2 , HC≡C-Si(Me) _{2- CH2} -Si(Me) ₃ , Me-C
≡C-Si(Me) ₂ -OH ₂ -Si(Me) ₃ , Me-C≡C
-Si(Me) ₂ -O-Si(Me) ₃ , Me-C≡C-Si
(Me) ₂ −CH ₂ CH ₂ −Si(Me) ₃ , Me−C≡C−Si
(Me) ₂ -O-Si(Me) ₂ -O-Si(Me) ₃ , Me-C
≡C-Si(Me) ₂ -CH ₂ -Si(Me) ₂ -CH=CH ₂ ,
Me-C≡C-Si(Me) ₂ -CH ₂ -SiCl ₃ , Me-C
≡C-Si(Me) _{2 -CH2} -Si(OMe) ₃ . The copolymer of the monomer compound of the general formula () and the monomer compound of the general formula () exemplified above can be obtained as follows. That is, a copolymerization reaction is carried out by reacting the organic unsaturated compound in an organic solvent such as toluene or cyclohexane in the presence of a polymerization catalyst such as WCl ₆ , NbCl ₅ or TaCl ₅ at a temperature of 30 to 130°C. The copolymer produced is precipitated, purified, and recovered as necessary. The copolymerization molar ratio of the monomer compound of general formula () and the monomer compound of general formula () is preferably 0.01≦()/()+()≦0.45, and the above molar The ratio is
When it is 0.45 or more, the oxygen permeation rate of the copolymer decreases rapidly, and on the other hand, when it is 0.01 or less, sufficient ultraviolet resistance strength cannot be obtained. Although the copolymer obtained in this way varies somewhat depending on its composition, it has sufficient UV resistance and has an oxygen permeability coefficient (PO ₂ ) of 5×10 ^-7 cm ³ as an oxygen permeation property. (STP)/cm ² · cmHg · sec or more, PO ₂ /PN ₂ = 1.5 to 2.0. The copolymer can be cast into a suitable form as a solution in an organic solvent such as toluene or cyclohexane to form films having various thicknesses. Of course, the polymer film may be formed on a nonwoven fabric, a base fabric, a porous membrane, or other thin film in order to overcome the operational problems caused by thinning the film. Examples of the porous membrane include porous polypropylene film, porous polyethylene film, porous polysulfone film, porous cellulose acetate film, porous ethylene tetrafluoride film, and porous polyimide film. The present invention is directed to copolymer molded products (e.g. films).
A low-temperature plasma polymerized film of organosilicon compound gas is formed on the surface, which provides high gas separation performance and high oxygen/nitrogen gas separation performance.
As a method for forming a low-temperature plasma polymerized film of organosilicon compound gas, a polymer molded product is placed in a low-temperature plasma generator, and while the organosilicon compound gas is flowing through the device, the inside of the device is heated for 10 minutes. A method may be used in which the pressure is adjusted and maintained at a pressure of Torr or less, low-temperature plasma is generated under this gas pressure, and the molded article is exposed to the low-temperature plasma. In addition, an inert gas such as helium or argon, or an inorganic gas such as nitrogen, oxygen, air, hydrogen, water vapor, carbon dioxide, or carbon monoxide may coexist with the organosilicon compound. In the above method, if the pressure of the organosilicon compound gas in the apparatus is too high, it will be difficult to form a plasma polymerized film on the surface of the compact, so the gas pressure of this low-temperature plasma is preferably 10 torr or less, In particular, a range of 0.001 to 5 Torr is preferred. The low temperature plasma at this gas pressure forms a plasma polymerized membrane with excellent gas separation properties. The electrical conditions for generating low-temperature plasma are, for example, 10KHz to 100MHz and 10W on the electrode.
It is enough to apply ~100KW power, and the internal electrode,
Any type of external electrode (electrodeless) may be used. The copolymer molded product is exposed to low-temperature plasma generated under the above conditions, and the film thickness for forming a plasma polymerized film of an organosilicon compound on its surface is 0.005 to 1μ, preferably 0.02 to 0.2μ. It is preferable to set it to μ. If the film thickness is too thin, the improvement in the separation coefficient that is the objective of the present invention will not be sufficient; if the film thickness is too thick, although the separation coefficient will be improved, the gas permeability will deteriorate, which is a problem in the present invention. The advantage of the invention is lost. The processing time for forming the above film thickness varies depending on the applied power, but generally several seconds to several minutes is sufficient. In the plasma treatment according to the present invention, specific examples of the organosilicon compounds supplied into the apparatus are as follows. Organosilicon compounds Trimethylchlorosilane, trimethylmethoxysilane, trimethylethoxysilane, vinyldimethylchlorosilane, vinyldimermethoxysilane, vinyldimethylethoxysilane, ethynyldimethylmethoxysilane, ethynyldimethylchlorosilane, methylchloromethylmethoxychlorosilane, triethylmethoxysilane, dimethyl Chloromethylethoxysilane, dimethylchloromethylchlorosilane, dimethylphenylmethoxysilane,
2-chloroethynyldimethylchlorosilane, 2-
Chloroethyldimethylmethoxysilane, dimethyldichlorosilane, dimethyldimethoxysilane, diethyldimethoxysilane, dimethyldiethoxysilane, vinylmethyldichlorosilane, vinylmethyldimethoxysilane, 2-chloroethylmethyldimethoxysilane, vinylmethyldiethoxysilane, chloromethylmethyl Dichlorosilane, dimethoxymethylphenylsilane, chloromethylmethyldimethoxysilane, methyltrimethoxysilane,
Methyltrinitoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, chloromethyltrimethoxysilane, 2-chloroethyltrimethoxysilane, trifluoropropyltrichlorosilane, tetravinylsilane, trivinylmethylsilane, divinyldimethylsilane, vinyltrimethyl Silane, divinyltetramethyldisiloxane, dichloromethyltetramethyldisiloxane,
Diethynyltetramethyldisiloxane, tetramethyldisiloxane, hexamethyldisiloxane,
Hexamethyldisilazane, octamethylcyclotetrasiloxane, hexamethylsilphenylene, etc. Next, comparative examples and examples will be given, but the present invention is not limited thereto. Comparative Example 1 1g of polymerization catalyst TaCl ₅ was dissolved in 200g of toluene,
Then, as a monomer compound, Me-C≡C-Si
20g of (Me) ₃ was added and polymerization was carried out at a temperature of 80°C for 5 hours. The produced polymer was purified by precipitation in excess methanol. This results almost quantitatively in the equation

A polymer having the main chain structural formula of [Formula] was obtained. Using this polymer, a thin film with a thickness of 3 μm was prepared by a casting method using a toluene solution.
This is designated as sample A. Next, apply 200W to this sample A.
UV light was irradiated for 48 hours using a high-pressure mercury lamp.
This is designated as sample B. Set sample A in the plasma device and check the inside of the device.
After reducing the pressure to 0.01 Torr, vinyltrimethylsilane gas was introduced into the apparatus, and the pressure was adjusted and maintained at 0.4 Torr. In this state, high-frequency power of 13.56MHz 100W was applied and plasma polymerization was performed on sample A for 5 minutes. Sample C was obtained. Similarly, high-frequency power of 13.56MHz 5kW was applied and plasma polymerization was performed for 20 seconds on sample A. was designated as sample D. Further, the surface of Sample C that had not been subjected to plasma polymerization treatment was irradiated with UV light for 10 hours using a 200W high-pressure mercury lamp. This is designated as sample E. Changes in molecular weight and oxygen gas permeation rate (PO ₂ ) measured by GPC for samples A to E,
The oxygen-nitrogen separation coefficient (PO ₂ /PN ₂ ) was measured to evaluate the mechanical strength and gas permeation properties of the membrane. The results are shown in Table-1. Example 1 1g of polymerization catalyst TaCl ₅ was dissolved in 200g of toluene,
As a monomer compound, 19 g of Me-C≡C-Si(Me) ₃ (this is referred to as A), Me-C≡C-Si(Me) ₂ -CH ₂ -Si(Me) ₃ (this is referred to as B ) is 1g (molar ratio B/(A+B)=
0.031) and polymerized at 80℃ for 5 hours, A polymer having the main chain structural formula was obtained. Using this polymer, a thin film with a thickness of 3 μm was prepared by a casting method using a toluene solution.
This is designated as sample F. Next, apply 200W to this sample F.
UV light was irradiated for 48 hours using a high-pressure mercury lamp.
This is designated as sample G. Set sample F in the plasma device and check the inside of the device.
After reducing the pressure to 0.01 Torr, vinyltrimethylsilane gas was introduced into the apparatus, and the pressure was adjusted and maintained at 0.4 Torr. In this state, a high frequency power of 13.56 MHz 100 W was applied and plasma polymerization was performed on sample F for 5 minutes. Sample H was obtained. Similarly, high frequency power of 13.56 MHz 5 kW was applied and plasma polymerization was performed for 20 seconds on sample F. was treated as the treatment. Further, the surface of Sample H that had not been subjected to plasma polymerization treatment was irradiated with UV light for 10 hours using a 200 W high-pressure mercury lamp. This is designated as sample J. For samples F to J, changes in molecular weight (), oxygen gas permeation rate (PO ₂ ), and oxygen-nitrogen separation coefficient (PO ₂ /PN ₂ ) were measured using GPC, and the mechanical strength and gas permeation characteristics of the membrane were determined. was evaluated. The results are shown in Table-1. Example 2 In Example 1, 10 g of monomer compound A, B
was changed to 10 g (molar ratio B/A+B=0.38), and other polymerization conditions, plasma polymerization conditions, and UV irradiation conditions were kept the same to prepare samples K, L, M, N, and O, respectively. The molecular weight, oxygen gas permeation rate ( _PO2 ), and oxygen-nitrogen separation coefficient ( _PO2 / _PN2 ) were measured for these. The results are shown in Table-1. Example 3 In Example 1, 15 g of monomer compound A and 5 g of a monomer of the formula Me-C≡C-Si(Me) ₂ -O-Si(Me) ₃ (this is designated as C) The polymerization conditions were the same except for the used (molar ratio C/A + C = 0.18), A polymer having the main chain structural formula was obtained. Regarding this, film formation, plasma polymerization conditions, UV
Under the same irradiation conditions, samples P, Q, R,
We made prototypes of S and T and conducted various tests as in the previous example. The results are shown in Table-1. Example 4 In Example 1, 18 g of monomer compound A and the formula Me-C≡C-Si(Me) ₂ -SiCl ₃ (which was converted to D
2g of the monomer (molar ratio D/A
+D=0.068) Other polymerization conditions were the same, A polymer having the main chain structural formula was obtained. Regarding this, film formation, plasma polymerization conditions, UV
Under the same irradiation conditions, samples U, V, W,
We made prototypes of X and Y and conducted various tests as in the previous example. The results are shown in Table-1.

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Claims (1)

[Claims] 1. General formula The monomer compound represented by and the general formula A composite molded article for gas separation, comprising a low-temperature plasma polymerized film of organosilicon compound gas formed on the surface of a copolymer molded article with a monomer compound represented by: In each of the above formulas, R ¹ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 4 carbon atoms,
R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are hydrogen atoms, halogen atoms, substituted or unsubstituted monovalent hydrocarbon groups having 1 to 4 carbon atoms, or alkoxy groups having 1 to 8 carbon atoms;
A is an oxygen atom, a divalent hydrocarbon group having 1 to 4 carbon atoms,
or a divalent group represented by the formula [-O-Si( ^R7 )( ^R8 )] _o , ^R7 and ^R8 are substituted or unsubstituted monovalent hydrocarbon groups having 1 to 4 carbon atoms, and n is 1 The number is ~3.