JPH0521011B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a gas separation membrane material made of a fluorine-containing polymer that is mainly used for concentrating oxygen in the air. [Prior Art] It has been proposed in the past to use gas separation membranes made of polymeric materials to obtain oxygen-enriched air from air. The material for this gas separation membrane is, for example, a polymer of fluoroalkyl acrylate (see Japanese Patent Laid-Open No. 59-6905), but this is easily broken due to lack of mechanical strength, making it impractical. isn't it. [Purpose of the Invention] The present inventors made gas separation membranes from various acrylic ester polymers and searched for membranes with high mechanical strength and ability to condense oxygen.
The present invention was achieved by discovering that a polymer mainly composed of fluoroalkyl acrylate having fluorine at the position thereof is excellent in these properties. An object of the present invention is to provide a practical new gas separation membrane material. [Structure of the Invention] The gist of the present invention is the general formula: (In the formula, Rf represents a fluoroalkyl group having 2 to 10 carbon atoms.) 50 to 100% by weight of structural units represented by the general formula: (In the formula, R ¹ is hydrogen, a hydroxyalkyl group having 2 to 10 carbon atoms, a hydroxyfluoroalkyl group having 2 to 10 carbon atoms, or a glycidyl alkyl group having 3 to 10 carbon atoms, and X is hydrogen, chlorine, fluorine, methyl group or a fluoroalkyl group having 1 to 3 carbon atoms.) 0 to 50% by weight of structural units represented by and general formula: (In the formula, R ² is a fluoroalkyl group having 2 to 10 carbon atoms, Y is hydrogen, chlorine, a methyl group, or a fluoroalkyl group having 1 to 10 carbon atoms.
3 shows the fluoroalkyl group. ) The gas separation membrane material consists of a polymer containing 0 to 50% by weight of structural units represented by When the structural unit (a) is contained in the specific polymer, the gas separation membrane made of this polymer has good mechanical strength and oxygen permeability. The preferred amount ratio of structural unit (a) contained is 70 to 100% by weight. When the structural unit (b) contains a carboxyl group, a hydroxyl group, and/or a glycidyl group as a functional group, this functional group is reacted with a crosslinking agent described below to crosslink the polymer, and the polymer has sufficient properties as a gas separation membrane. It can give strength. Structural units containing functional groups
The preferred amount ratio of (b) contained in the polymer is 10% by weight.
It is as follows. The structural unit (c) may be included in the polymer within the above range so as not to impair the mechanical strength of the gas separation membrane. The above polymer has the general formula: (In the formula, Rf is the same as above.) Either the monomer represented by the formula is homopolymerized, or the monomer (a') is 50% by weight or more and less than 100% by weight and the general formula: (In the formula, X and R ¹ are the same as above.) Monomer and/or general formula represented by: (In the formula, Y and R ² are the same as above.) It can be obtained by copolymerizing the remaining monomers. Other ethylenic monomers may be copolymerized as long as the properties such as oxygen permeability of the gas separation membrane are not impaired. The polymerization method may be any of the usual radical polymerization solutions, suspensions, emulsifications, bulk polymerizations, etc., but usually solution polymerization is employed, which does not require the polymer produced by polymerization to be dissolved in a solvent again. Solvents commonly used in solution and suspension polymerizations are:
Fluorine-based solvents, such as hexafluorotaxylene, 1,1,2-trichloro-1,2,2-trifluoroethane, 1,2,4,4-tetrachloro-1,1,2,3, Examples include 3,4-hexafluorobutane. Hydrocarbon solvents can also be used. A mixture of a fluorine-based solvent and a hydrocarbon-based solvent can also be used. In solution, suspension and bulk polymerization, the polymerization initiator is an organic peroxide such as benzoyl peroxide, dicumyl peroxide, tertiary butyl peroxyisobutyrate, diisopropyl peroxydicarbonate, azobisisobutyronitrile,
Examples include azo compounds such as azobisvaleronitrile. In emulsion polymerization, a redox initiator consisting of an oxidizing agent such as ammonium persulfate or potassium persulfate, or a combination of these oxidizing agents, a reducing agent such as sodium sulfite, and a salt of a transition metal such as iron sulfate is exemplified. can. The polymerization initiator is usually used in an amount of 0.01 to 5% by weight based on the total monomers. Polymerization temperature is 0 to 150℃ for all polymerization methods.
It is. The copolymers prepared by each of the above polymerization methods are dissolved in the solvent used in the solution polymerization, and since the copolymers prepared by solution polymerization are already dissolved in the solvent, they are concentrated or diluted as appropriate and then polymerized. When crosslinking the coalescence, a crosslinking agent is added to prepare a normal thin film, such as bar coater method, spin coater method,
The film thickness is usually 0.1 to 50 μm on a smooth plate such as glass or metal or a porous support such as porous polytetrafluoroethylene using the Young-Miller method or the dip method.
Form a film so that When a polymer film is formed on a smooth plate of ordinary glass or metal, etc., if the polymer is crosslinked, it is reacted with a crosslinking agent, then peeled off from the plate and fixed on a suitable porous support. In addition, when a film formed on a porous support is crosslinked, it is reacted with a crosslinking agent and then used together with the support as a gas separation membrane. When the functional group contained in the copolymer is a carboxyl group, the crosslinking agent is a compound having two or more amino groups, glycidyl groups, or isocyanate groups, such as ethylenediamine, hexamethylene diamine, butylene diglycidyl ether, etc. : Examples include compounds represented by the following, hexamethylene diisocyanate trimer, tolylene diisocyanate, and the like. When the functional group is a hydroxyl group, in addition to the above-mentioned isocyanate compounds, compounds having two or more acid halides, such as hexamethylene dicarbonyl chloride, can also be used. When the functional group is a glycidyl group, in addition to the above-mentioned amino group-containing compound, a Lewis acid such as BF ₃ , HCl, etc., which generates BF ₃ upon irradiation with light:

〔Example〕

Examples 1 to 3 100 g of monomer (a') shown in Table 1, ethyl acetate
200 g, azobisisobutyronitrile 0.015 g, and lauryl mercaptan 0.6 g were placed in a glass autoclave, cooled with a dry ice-methanol cryogen, and degassed. Thereafter, it was heated to 50°C to start polymerization. The temperature was maintained for 24 hours with stirring. Ethyl acetate was added to the reaction mixture and mixed so that the solid content concentration was 7% by weight. The resulting solution was applied onto a glass plate to a thickness of 100 μm using a doctor knife and air-dried. The dried membrane was peeled off from the glass plate to prepare a gas separation membrane sample. For the obtained sample, the permeability coefficients of oxygen and nitrogen (unit: cc・cm/cm ²・sec・cmHg) and the separation coefficient of oxygen for nitrogen were determined by ASTM using the following conditions.
Obtained using the D1434V method. Table 1 shows the oxygen permeability coefficient and separation coefficient (versus nitrogen).
shows. Gas used: Standard gas mixture of 79% nitrogen and 21% oxygen by volume. Pressure: Primary pressure 5Kg/cm ² , secondary pressure 1Kg/cm ² (both absolute pressure). Gas permeation amount: 4c.c. Time: Time required for the above gas permeation. Area: ^135cm2 . Film thickness: The value obtained by weighing the weight of the polymer attached to the support and dividing this value by the area of polymer attachment and the specific gravity of the polymer. Examples 4-5 100 g of monomer (a') shown in Table 1, ethyl acetate
200 g, azobisisobutyronitrile 0.015 g, and lauryl mercaptan 0.6 g were placed in a glass autoclave, cooled with a dry ice-methanol cryogen, and degassed. Thereafter, it was heated to 50°C to start polymerization. The temperature was maintained for 24 hours with stirring. 3133 g of ethyl acetate was added to the resulting reaction mixture. This solution was applied onto a polypropylene porous body (Jyuraguard manufactured by Polyplastics Co., Ltd.) using a spin coater rotating at 2,000 revolutions per minute, and then the porous body was cut to a size of 150 mm to prepare a gas separation membrane sample. The permeability coefficients of oxygen and nitrogen and the separation coefficient of oxygen with respect to nitrogen were determined under the same conditions as in Examples 1 to 3. Table 1 shows the oxygen permeability coefficient and separation coefficient (versus nitrogen).
shows. Examples 6-10 Monomer (a') and monomer (b') shown in Table 1
Polymerization was carried out in the same manner as in Example 1 except that monomer (a') in Example 1 was used in a total of 100 g. The obtained reaction mixture was diluted in the same manner as in Example 1, 1.5 parts by weight of hexamethylene diisocyanate trimer was added per 100 parts by weight of this solution, and a film was formed in the same manner as in Examples 4 and 5. . Thereafter, the copolymer was left to stand at room temperature for 7 days to crosslink.
Samples of the same size as in Examples 4 and 5 were prepared, and the permeability coefficients of oxygen and nitrogen and the dispersion coefficient of oxygen with respect to nitrogen were determined under the same conditions as above. Table 1 shows the oxygen permeability coefficient and separation coefficient (versus nitrogen).
shows. Example 11 Monomer (a') and monomer (b') shown in Table 1
Gas separation membrane samples were prepared in the same manner as in Examples 1 to 3 above, except that a total of 100 g was used instead of monomer (a'), and the permeability coefficients of oxygen and nitrogen and the permeability coefficients of oxygen and nitrogen were determined under the same conditions as above. The separation coefficient was determined. Table 1 shows the oxygen permeability coefficient and separation coefficient (versus nitrogen).
shows. Example 12 Monomer (a') and monomer (c') shown in Table 1
Gas separation membrane samples were prepared in the same manner as in Examples 1 to 3 above, except that a total of 100 g was used instead of monomer (a'), and the permeability coefficients of oxygen and nitrogen and the permeability coefficients of oxygen and nitrogen were determined under the same conditions as above. The separation coefficient was determined. Table 1 shows the oxygen permeability coefficient and separation coefficient (versus nitrogen).
shows. Comparative Examples 1 to 6 100 ml of water and 0.1 g of polyvinyl alcohol were placed in a 300 ml four-necked flask and stirred while passing nitrogen through the flask to dissolve the polyvinyl alcohol in the water.
The fluorine-containing monomer 30 shown in Table 2 was added to the obtained solution.
g, 0.15 g of dodecyl mercaptan and 0.15 g of lauroyl peroxide were added and the mixture was kept at 60° C. for 4 hours with stirring to polymerize the methacrylate. Thereafter, the produced polymer was filtered, washed with water, and vacuum dried at 50°C for 24 hours. Add 10g of the obtained dry polymer to 90g of acetone.
The solution was cast onto a glass plate to a thickness of 250 μm and air-dried. When attempting to peel off the dried polymer film, cracks appeared and a clean film could not be obtained. Therefore, the reaction mixture after polymerization was applied onto a porous body in the same manner as in Examples 4 and 5 to prepare a gas separation membrane sample, and the permeability coefficients of oxygen and nitrogen and the separation coefficient of oxygen to nitrogen were determined under the same conditions as above. Ta. Table 2 shows the oxygen permeability coefficient and separation coefficient (versus nitrogen). It should be noted that polymer membranes are extremely susceptible to cracks, so measurements had to be carried out with care. Monomers in Tables 1 and 2 below: ~
refer to the following compounds, respectively. CH ₂ = CFCOOCH ₂ CF ₃ CH ₂ = CFCOOCH ₂ (CF ₂ ) ₂ H CH ₂ = CFCOOCH ₂ (CF ₂ ) ₂ F CH ₂ = CFCOOCH ₂ (CF ₂ ) ₄ H CH ₂ = CFCOOCH ₂ (CF ₂ ) ₄ F CH ₂ = CFCOOCH ₂ CH(OH)−CH ₂ (CF ₂ ) ₄ F CH ₂ = CFCOOCH ₂ CH(OH)−CH ₂
(CF ₂ ) ₂ CF (CF ₃ ) ₂ CH ₂ = CFCOOCH ₂ CH ₂ OH CH ₂ = CFCOOH

[Formula] xi CH ₂ = CFCOOCH ₃ xii CH ₂ = CH (CH ₃ ) COOCH ₂ (CF ₂ ) ₂ H CH ₂ = CH (CH ₃ ) COOCH ₂ (CF ₂ ) ₈ H CH ₂ = C (CH ₃ ) COOC(CF ₃ ) ₂ CF _2- CH
(CF ₃ ) ₂ CH ₂ =C(CH ₃ )COOC(CF ₃ ) ₂ CF ₂ −
CF ₂ ) ₄ H CH ₂ =C(CH ₃ )COOCH ₂ CH(OCO−
CH ₃ ) CH ₂ (CF ₂ ) ₇ CF (CF ₃ ) ₂ CH ₂ =C(CH ₃ )COOCH ₂ CH(OH)−
(CF ₂ ) ₇ CF (CF ₃ ) ₂ CH ₂ =C(CH ₃ ) COOCH ₂ (CF ₂ ) ₂ F

【table】

〔Effect of the invention〕

The gas separation membrane manufactured from the material of the present invention, which is made of a polymer of fluoroalkyl acrylate having fluorine at the α-position, has superior mechanical strength compared to conventional gas separation membranes, and also has a good oxygen concentrating ability. It is something.

Claims (1)

[Claims] 1. General formula: (In the formula, Rf represents a fluoroalkyl group having 2 to 10 carbon atoms.) 50 to 100% by weight of structural units represented by the general formula: (In the formula, R ¹ is hydrogen, an alkyl group having 1 to 10 carbon atoms,
Hydroxyalkyl group having 2 to 10 carbon atoms, 2 carbon atoms
-10 hydroxyfluoroalkyl group or C3-C10 glycidyl alkyl group, X represents hydrogen, chlorine, fluorine, methyl group or C1-3 fluoroalkyl group. ) Structural units represented by 0 to 50% by weight and general formula: (In the formula, R ² is a fluoroalkyl group having 2 to 10 carbon atoms, Y is hydrogen, chlorine, a methyl group, or a fluoroalkyl group having 1 to 10 carbon atoms.
3 shows the fluoroalkyl group. ) A gas separation membrane material consisting of a polymer containing 0 to 50% by weight of structural units represented by: