JPH0215246B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a gas selectively permeable membrane, and in particular aims to provide a gas selectively permeable membrane having high selective permselectivity for oxygen gas. In particular, the present invention relates to a novel gas selective permeation membrane that can achieve facilitated transport of oxygen gas using a polysiloxane membrane containing a metal complex structure that can reversibly adsorb and desorb oxygen gas. . Generally, in a homogeneous polymer membrane, the permeability coefficient of oxygen gas is higher than that of nitrogen gas, and if economic efficiency is ignored, it is possible to separate and concentrate oxygen gas. However, in polydimethylsiloxane with a high oxygen permeability coefficient, the value of the separation coefficient (= oxygen permeability coefficient / nitrogen permeability coefficient) is
On the other hand, poly(2,6-dimethyl)phenylene oxide and poly(4-methylpentene-1), which have a high separation coefficient, have an oxygen gas permeability coefficient of 10 ^-9 cm ³ cm. / ^cm2・sec・
cmHg order and compared to polydimethylsiloxane,
It remains at an order of magnitude lower level. As mentioned above,
Membrane materials with high levels of both oxygen gas permeability coefficient and separation coefficient are extremely difficult to achieve in the conventional polymer synthesis technology field, and membrane materials that mimic the functions of biological molecules such as hemoglobin and hemocyanin are being developed. There are increasing expectations for membranes that facilitate the transport of gas molecules. In an attempt to facilitate the transport of gas using a carrier material that can perform selective adsorption/desorption interactions with gas molecules, a membrane made of crosslinked polyethyleneimine has been proposed (Tsuchida et al. et al., Makromol.Chem.Rapid Commun 3 ,
693 (1983)). In this report, by introducing cobalt divalent ions into a polyethyleneimine crosslinked membrane,
Although it has been confirmed that oxygen gas is adsorbed by the membrane, cobalt ions promote the formation of intermolecular crosslinks between polyethyleneimine chains, so the oxygen gas permeability coefficient is lower than that of membranes that do not contain cobalt ions. The problem is that it drops to about 1/3. Therefore, it is considered impossible to improve both oxygen gas permeability and separation coefficient in this system. Additionally, it has been reported that facilitated transport of oxygen gas is possible using a liquid membrane formed by impregnating the pores of a porous membrane with a tetraethylenepentamine-CuSCN complex (Kakagawa et al., JCSChem.Commun. (1983). )),
Since the amine compound constituting the functional membrane is volatile, it has the disadvantage that it cannot withstand long-term use. Furthermore, since the functional film itself is liquid, it is difficult to form it into an ultra-thin film. There is a problem with this. As described above, it has been difficult to achieve a gas facilitated transport membrane containing a metal complex structure that is excellent in both oxygen gas permeability and separation coefficient using conventional techniques. The present invention provides a gas selective permeation membrane made of a polysiloxane polymer having a nitrogen-containing ligand of 0.01 meq/g or more, wherein the nitrogen-containing ligand is an amino group,
A ligand containing at least one selected from an imidazole group, a pyridyl group, and a Schiff base, and characterized in that the polymer contains 10 ^-6 milliequivalents/g or more of divalent cobalt or monovalent copper ions. This invention relates to a gas selectively permeable membrane. The polysiloxane polymer of the present invention has Si in the main chain.
Any polymer may be used as long as it has an -O bond, and its number average molecular weight is preferably 1,000 or more, more preferably 5,000 or more. The gas selectively permeable membrane of the present invention is mainly composed of a polysiloxane polymer having a metal complex structure in the side chain, and the structural units listed below are copolymerized in an amount of less than 40% by weight based on the total weight of the membrane. Or it may be blended.

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(−CH ₂ CH ₂ O)−,

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[Formula] (X is

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[Formula] -CH ₂ -, -S-,

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[Formula] (Ar is

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[Formula]) The content of nitrogen-containing ligands in the polysiloxane polymer of the present invention is preferably 0.01 meq/g of polymer or more, more preferably 0.1 meq/g.
- More than a polymer. The content of nitrogen-containing ligands is
When the amount is less than 0.01 milliequivalent, the effect of promoting oxygen gas transport is not sufficiently expressed. Examples of polysiloxane polymers having nitrogen-containing ligands in their side chains include those containing the structural units shown below, but are not particularly limited thereto. (1) Amino group-containing type

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[Formula] (2) Imidazole group-containing type (3) Pyridyl group-containing type (4) Schiff base-containing type Introducing divalent cobalt or monovalent copper ions into the polysiloxane polymer containing nitrogen-containing ligands of the present invention can be carried out by the following method. A polysiloxane polymer having a ligand in its side chain is synthesized, and a desired polymeric metal complex is synthesized by reacting this with a metal ion. Low-molecular complexes synthesized from low-molecular ligands and metal ions (such as Co(Salen) complexes)
and a polysiloxane having a ligand in its side chain are reacted. When introducing a ligand structure into the side chain of a polysiloxane polymer, a metal ion is allowed to coexist to synthesize a polymeric metal complex through a 1-pot reaction. A polysiloxane polymer having a ligand in a side chain is formed into a film in advance, and this film is brought into contact with a solution of metal ions to introduce metal ions into the polysiloxane polymer. Divalent cobalt or monovalent cobalt in the polymer of the present invention
The content of valent copper ions is preferably at least 10 ^-6 meq/g, more preferably at least 10 ^-3 meq/g per gram of polymer. When the content of metal ions is less than 10 ^-6 milliequivalents/g, the effect of promoting oxygen gas transport is not sufficiently expressed. In the present invention, by using a selectively permeable membrane that has a skeleton structure of a polysiloxane polymer with excellent gas permeability and a metal complex structure that can reversibly adsorb and desorb oxygen gas in its side chain, This makes it possible to achieve high levels of both oxygen permeability and separation performance, which were difficult to achieve within the current technology. Hereinafter, the present invention will be specifically explained with reference to Examples. Comparative Example 1 5 g of (N-2-aminoethyl-3-aminopropyl)methyldimethoxysilane was mixed with 5 ml of water and stirred at 70°C for 2 hours to obtain a hydrolyzate.
The reaction mixture was heated to 100° C. under a reduced pressure of 5 mmHg, and the volatile components were distilled off. The structure of the product is ^1H
From the knowledge of the NMR spectrum, it was shown by the following formula. The degree of polymerization n was confirmed to be about 10 as a result of end group analysis using ¹ H NMR spectrum. This amine group-containing polysiloxane oligomer (oil) was uniformly applied to a thickness of 45 microns on a porous polypropylene film (Celgard 2400) to form a composite membrane. The permeation rate of oxygen gas and nitrogen gas through this composite membrane was evaluated at 20°C using a gas permeability measuring device (manufactured by Yanagimoto Seisakusho) using gas chromatography (primary pressure
1.5atm, secondary pressure 0.026atm), oxygen permeation rate (Qo ₂ )
is 2.6×10 ^-7 cm ³ /cm ²・sec・cmHg, the nitrogen permeation rate (Q _N2 ) is 9.6×10 ⁻⁸ cm ³ /cm ²・sec・cmHg, and the separation coefficient (Qo ₂ /Qn ₂ ) was 2.7. Example 1 8 mmol of CuSCN was reacted with 1 mol (per repeating unit) of the α, ω dimethoxypolysiloxane synthesized in Comparative Example 1 to produce a polysiloxane (viscous oily substance) containing a blue-colored complex structure. I got it. This polysiloxane was uniformly laminated on a porous polypropylene film (Celgard 2400) to prepare a composite membrane. The thickness of the polysiloxane layer in this composite membrane was 30 microns. When the permeation rate of oxygen gas and nitrogen gas through this composite membrane was evaluated under the same conditions as in Comparative Example 1, the oxygen gas permeation rate was 5.0×10 ^-7 cm ³ /cm ² ·sec.
cmHg, nitrogen gas permeation rate is 8.5×10 ^-8 cm ³ /cm ² .
It was sec/cmHg. Comparing the results of this membrane performance with those obtained in Comparative Example 1, the introduction of monovalent copper ions into the amino group-containing polysiloxane significantly improves the separation coefficient while maintaining the oxygen permeation rate at the same level. It was confirmed that it is possible to do so. Comparative Example 2 A cohydrolysis reaction of dimethyldiethoxysilane and N-(trimethoxysilylpropyl)imidazole was carried out at a molar ratio of both compounds of 1:1 to obtain a polysiloxane containing an imidazole group. This polysiloxane was a highly viscous oil-like substance. This polysiloxane was uniformly laminated on a porous polypropylene film (Celgard 2400) to prepare a composite membrane. The thickness of the polysiloxane layer in the composite membrane was 30 microns. When the permeation rate of oxygen gas and nitrogen gas through this composite membrane was evaluated in the same manner as in Comparative Example 1, the oxygen gas permeation rate was 2.1×10 ^-8 cm ³ /cm ² ·sec·cmHg, and the nitrogen gas permeation rate was It was 1.0×10 ⁻⁸ cm ³ /cm ² ·sec·cmHg, and the separation coefficient was 2.1. Example 2 1 g of the imidazole group-containing polysiloxane synthesized in Comparative Example 2 (calculated as imidazole nuclei)
4.11 mmol) was reacted with 20 mg (0.164 mmol) of CuSCN to obtain a polysiloxane containing a complex structure for blue color. This polysiloxane was a viscous oily substance. This polysiloxane was uniformly laminated on a porous polypropylene film to prepare a composite membrane. The thickness of the polysiloxane layer in this composite membrane was 35 microns. When the oxygen and nitrogen gas permeation rates through this composite membrane were evaluated in the same manner as in Comparative Example 1, the oxygen gas permeation rate was 2.5×10 ^-8 cm ³ /cm ^{2 ·sec·cmHg, and the nitrogen gas permeation rate was 2.5×10 -8 cm 3 /cm 2} ·sec · cmHg. is 8.3×10 ^-9 cm ³ /cm ²・sec・cmHg,
The separation factor was 3.0. Comparing the membrane performance results obtained here with those obtained in Comparative Example 2, it is found that the introduction of monovalent copper ions into the imidazole group-containing polysiloxane maintains the oxygen permeation rate at the same level while increasing the separation coefficient. It was confirmed that it is possible to improve. Comparative Example 3 A polysiloxane oligomer containing a pyridine nucleus was synthesized by a cohydrolysis reaction of β-triethoxysilyl-4-ethylpyridine and dimethyldiethoxysilane (charged molar ratio 1:1.5). This compound was a viscous oil. A composite membrane was prepared by uniformly layering a pyridine nucleus-containing siloxane oligomer on a porous polypropylene film (Celgard). The thickness of the polysiloxane layer in this composite membrane was 35 microns. Comparative Example 1 The permeation rates of oxygen gas and nitrogen gas through this composite membrane
When evaluated using the same method as above, the permeation rate of oxygen gas was 5.4×10 ^-8 cm ³ /cm ²・sec・cmHg, and the permeation rate of nitrogen gas was 2.3×10 ⁻⁸ cm ³ /cm ²・sec・cmHg. , the separation factor was 2.4. Example 3 In Comparative Example 3, 1 g of the synthesized pyridine nucleus-containing polysiloxane (3.608 m in terms of pyridine nuclei)
mol) with 30 mg of Co(OAc) _{2.4H 2} O,
A composite membrane was prepared by uniformly layering a polysiloxane oligomer containing a complex structure on a porous polypropylene film. The thickness of the polysiloxane layer in this composite membrane was 25 microns. The permeation rate of oxygen gas through this composite membrane is 7.0×10 ^-8 cm ³ /
cm ²・sec・cmHg, nitrogen gas permeation rate is 2.0×10 ^-8
cm ³ /cm ² ·sec·cmHg, and the separation factor was 3.5.
Comparing the membrane performance results obtained here with the results of Comparative Example 3, it is found that the introduction of divalent cobalt ions into the polysiloxane containing pyridine nuclei improves the separation coefficient while maintaining the oxygen permeation rate at the same level. It turns out that it is possible to do so. Comparative Example 4 By stirring the amino group-containing polysiloxane oligomer synthesized in Comparative Example 1 and salicylaldehyde in benzene at room temperature for 24 hours,
A polysiloxane oligomer containing 7.4 Schiff base units per 10 siloxane bonds was obtained. This polysiloxane oligomer was uniformly laminated on a porous polypropylene film to prepare a composite membrane. The thickness of the siloxane layer in this composite membrane is 31
It was micron. The permeation rate of oxygen gas through this composite membrane is 9.7×10 ^-8 cm ³ /cm ²・sec・cmHg, and the permeation rate of nitrogen gas is 2.9×10 ⁻⁸ cm ³ /cm ²・sec・cm
Hg, and the separation factor was 3.3. Example 4 1.2 g of polysiloxane containing a Schiff base structure in the side chain synthesized in Comparative Example 4 (content of Schiff base units: 74 mol%) and Co(OAc) _{2.4H 2} O20
mg in ethyl alcohol to obtain a polysiloxane oligomer containing a metal complex structure.
This polysiloxane oligomer was uniformly laminated on a porous polypropylene film to prepare a composite membrane. The thickness of the polysiloxane layer in this composite membrane was 39 microns. The permeation rate of oxygen gas through this composite membrane is 1.9×10 ^-7 cm ³ /cm ²・sec・cm
The permeation rate of Hg and nitrogen gas is 2.7×10 ^-8 cm ³ /cm ² .
sec cmHg, and the separation coefficient was 7.0. Comparing the membrane performance results obtained here with the results of Comparative Example 4, it is possible to improve the separation coefficient by introducing divalent cobalt ions into polysiloxane containing a Schiff base structure. I understand.

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Claims (1)

[Claims] 1. A gas selective permeation membrane made of a polysiloxane polymer having a nitrogen-containing ligand of 0.01 meq/g or more, wherein the nitrogen-containing ligand is selected from an amino group, an imidazole group, a pyridyl group, and a Schiff base. 1. A gas selective permeation membrane, characterized in that the polymer contains at least one type of ligand, and the polymer contains 10 ^-6 milliequivalents/g or more of divalent cobalt or monovalent copper ions.