JPS6151934B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a gas separation membrane made of a polyquinazolone polymer. In recent years, gas separation using organic polymer membranes, especially oxygen enrichment of air, has been attracting attention from the viewpoint of resource and energy conservation.However, conventional oxygen enrichment membranes have an oxygen permeation rate that is too low or Since the permeability coefficient ratio of oxygen to nitrogen is small, it is not suitable for oxygen enrichment on an industrial scale. For example, polydimethylsiloxane has an oxygen permeability coefficient of 10 ^-8 cm ³
(STP)・cm/cm ²・sec・cmHg, which is the highest among conventionally known polymer membranes, but the permeability coefficient ratio for nitrogen is at most about 2, and the selective permeation of oxygen This method has poor performance and separation properties, and requires multistage membrane treatment in order to obtain a high concentration of oxygen, making it impractical in terms of both equipment and cost. Furthermore, this membrane has low mechanical strength and requires the use of a relatively thick membrane. Therefore, even if the permeation coefficient is large, the permeation rate cannot be increased. For this reason, Japanese Patent Publication No. 47-51715 proposed an oxygen-enriched membrane made of polyvinyltrimethylsilane, which improved the permeability coefficient ratio of oxygen to nitrogen to about twice that of polydimethylsiloxane, but was chemically resistant. It has the disadvantage of being easily degraded by pollutants in the air, oil from pumps, etc. Additionally, in recent years, in addition to oxygen enrichment membranes, with the development of so-called _C1 chemistry, gas separation membranes from synthesis gas have become necessary. Because it is used at high temperatures, extremely high heat resistance is required. As a result of intensive research in view of the above, the present inventors found that
The present invention was achieved based on the discovery that membranes made of polyxolone polymers have excellent gas permselectivity, permeation rate, chemical resistance, heat resistance, processability, and mechanical strength. The gas separation membrane of the present invention has the general formula (However, R ¹ is a tetravalent organic group, R ² is each independently an alkyl group or an aromatic group, and R ³ is (p+2)
A valent organic group, Z represents -COOH, -SO ₃ H or a metal salt thereof, and p is independently 0 or 1 for each unit.
Indicates an integer of ~4. ) It is characterized by being made of a polyquinazolone polymer having bisquinazolone units represented by the following as repeating units. In the polyquinazolone polymer represented by the above general formula (), R ¹ is a tetravalent aromatic group, preferably

【formula】

[Formula] or

[Formula] is. X combines two divalent aromatic groups to form 4
An organic bonding group that forms a valent aromatic group, and specific examples include -CH ₂ -, -C(CH ₃ ) ₂ -, -CO
―, ―SO ₂ ―O―, ―S―, ―NH―, ―COO
-, -CONH-, etc. can be mentioned. ^R2 is an alkyl group or an aromatic group, preferably an alkyl group having 1 to 4 carbon atoms, particularly preferably a methyl group or a phenyl group. Although two ^R2 's are bonded in the above repeating unit, they do not necessarily have to be the same. Next, R ³ is a divalent organic group, specifically an aromatic group,
It is an aliphatic or alicyclic divalent organic group, or a divalent organic group in which these groups are bonded via an organic bonding group Y. Here, specific examples of the bonding group Y are -CH ₂ -, -C(CH ₃ ) ₂ -, -CO-, -SO ₂ -,
-O-, -NH-, -S-, -CONH-, -COO
--,

【formula】

[Formula] (However, R ⁴ and R ⁵ each independently have a carbon number of 1
~10 alkyl group, cycloalkyl group having 3 to 10 carbon atoms, or phenyl group. ) etc. R ³ is preferably an aromatic group and when p=0, i.e. the repeating unit is (However, R ¹ , R ² and R ³ are the same as above.) In the case where

【formula】

【formula】

[Formula] (However, Y is the same as above.) etc. can be mentioned. Therefore, as a preferred specific example of unit (a), can be mentioned. A polyquinazolone polymer having unit (a) as a repeating unit has the general formula (However, R ¹ and R ² are the same as above.) Bisoxazinone represented by the general formula H ₂ N—R ³ —NH in an amount of 0.95 to 1.08 mol, preferably approximately 1 mol per mol of this bisoxazinone. ₂ () (However, R ³ is the same as above.) It is obtained by reacting the diamine represented by the following in an organic solvent under heating. In the bisoxazinone represented by the above general formula (), R ¹ and R ² are as described above,
Specific examples of bisoxazinone preferably used in the present invention include: etc. can be mentioned. Further, R ³ in the diamine represented by the above general formula () is the same as above, and specific examples of the diamine are m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4, 4′-diaminodiphenyl ether, 3,
4'-diaminodiphenyl ether-4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, p-bis(4-aminophenoxy)benzene, m-bis(4-aminophenoxy)benzene, N,N'-piperazine-bis-
(p-aminobenzoic acid amide), m-xylylenediamine, p-xylylenediamine, bis(4-aminocyclohexyl)methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, 1,4-diaminocyclohexane,
Examples include bis(4-aminophenyl)diethylsilane and bis(3-aminopropyl)tetramethyldisiloxane, which may be used alone or as a mixture. The method for producing bisoxazinone includes, for example,
As described in J. Polymer Sci., 60 , S 59 (1962) and Industrial Chemistry Journal 73 , 1239 (1970), it is already known, and usually the general formula (However, R ¹ is the same as above.) An aromatic diaminodicarboxylic acid represented by the general formula (However, R ² is the same as above.) or an aromatic carboxylic acid chloride represented by the general formula R ² -COCl (However, R ² is the same as above.) You can get it. Usually, the above-mentioned aromatic diaminodicarboxylic acids include 4,6-diaminoisophthalic acid, 2,5-diaminoterephthalic acid, 2,3-diaminoterephthalic acid, general formula (However, Y is the same as above.) Diaminodicarboxylic acids represented by the following are used, acetic anhydride and the like are used as acid anhydrides, and benzoyl chloride and the like are used as acid chlorides. The condensation reaction between bisoxazinone and diamine (2) is carried out in a solvent by heating. As a solvent, it is capable of dissolving bisoxazinone and diamine, and is inert to them.
Preferably, one is used that can also dissolve the produced polyquinazolone polymer and further maintains the reaction system in an acidic environment. Specific examples of preferred solvents include cresols such as p-cresol and m-cresol, chlorophenols such as p-chlorophenol and o-chlorophenol, polyphosphoric acid, and sulfuric acid, which may be used alone or in combination. It will be done. If necessary, a mixed solvent of these solvents and a nonpolar hydrocarbon solvent such as benzene, toluene, xylene, chlorobenzene, or naphtha may also be used. The amount of solvent used for the raw materials is not particularly limited, but is usually 60 to 900 parts by weight per 100 parts by weight of the total amount of bisoxazinone and diamine. The reaction temperature and reaction time between bisoxazinone and diamine vary depending on the types of these raw materials and the type of solvent used, but are usually 5 to 30 minutes at a temperature of 100 to 300°C.
Incubate for 50 hours. Next, R ³ and Z when p is an integer from 1 to 4
As a preferred example of and p

【formula】

【formula】

etc. can be mentioned. The above unit (a) and a unit represented by the following general formula (However, R ¹ , R ² , R ³ and Z are the same as above, and p is an integer of 1 to 4.) It can be similarly obtained by substituting with a diamine having a group Z. That is, the bisoxazinone represented by the general formula (), the diamine represented by the general formula (), and the general formula (However, R ³ is the same as above, p is 1 to 4
indicates an integer. ) is reacted with the diamine ( ) represented by the above in the organic solvent under heating under conditions such that the molar ratio of the total amount of these diamines to 1 mole of the bisoxazinone is 0.95 to 1.08, preferably approximately 1. The reaction conditions may be the same. Specific examples of the aromatic diamine represented by the above general formula () include 3,5-diaminobenzoic acid,
4,4'-diaminodiphenylmethane-3,3'-dicarboxylic acid, 3,5-diaminobenzenesulfonic acid, 3,3'-benzidinedicarboxylic acid, N,N'-
Bis(p-aminobenzoyl)-3,5-diaminobenzoic acid, isophthal-3-amino-5-carboxyanilide, 3,3'-benzidine disulfonic acid, 4,4'-diaminodiphenylmethane-3,
Examples include 3'-disulfonic acid. Furthermore, advantageously, the polyquinazolone polymer used in the present invention includes bisoxazinone, the diamine component (), and optionally ( ), preferably using a Lewis acid catalyst and a phosphorus-containing dehydrating agent, and by heating and reacting in an aprotic polar organic solvent. Examples of the aprotic polar organic solvent include N-methyl-
2-pyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, etc. are used. The amount of the solvent used is not particularly limited, but it is used so that the total amount of bisoxazinone and diamine components is 10 to 50% by weight, preferably 20 to 30% by weight. As the Lewis acid catalyst, metal halides, particularly chlorides, such as anhydrous stannous chloride, anhydrous cupric chloride, anhydrous cobalt chloride, anhydrous ferric chloride, and anhydrous nickel chloride are preferably used. The amount of catalyst used is per mole of bisoxazinone or diamine.
The amount is 0.002 to 0.2 mol, preferably 0.01 to 0.1 mol. If the amount of catalyst is too large, gelation will occur, which is not preferable. Examples of the phosphorus-containing dehydrating agent include phosphorus pentoxide, phosphoric acid, metaphosphoric acid, phosphorous acid, hypophosphoric acid, hypophosphorous acid, pyrophosphoric acid, polyphosphoric acid, etc., but phosphorus pentoxide is preferably used. The amount of the dehydrating agent used is 0.001 to 0.4 mol, preferably 0.01 to 0.2 mol, per 1 mol of bisoxazinone. Dehydrating agents effectively prevent gelation. Diamine having an acidic group itself has a catalytic effect in the polymerization reaction between bisoxazinone and diamine. Therefore, when at least a portion of the diamine component is diamine (), a high molecular weight polyquinazolone polymer can be obtained without particularly using a Lewis acid catalyst. The polymerization reaction is preferably carried out by adding a hydrocarbon solvent capable of azeotroping with water, such as benzene, xylene, toluene, etc., to the solvent, and removing reaction water produced by the polymerization from the system by azeotropy. The temperature of the polymerization reaction is 150 to 200°C, and the time is from several hours to several tens of hours, and usually within 100 hours is sufficient. In the present invention, all polyquinazolone polymers having unit () as a repeating unit have an intrinsic viscosity of
It is preferably in the range of 0.30 to 1.50, preferably 0.4 to 1.0. If the intrinsic viscosity is too small, the self-supporting properties will be poor when used as a gas separation membrane, and the mechanical strength will not be sufficient. On the other hand, if the intrinsic viscosity is too large, it will be difficult to obtain a uniform dope (film-forming liquid). This is because film formation is not easy. In the present invention, the unit (b) is 0 of all units.
It may account for ~70 mol%. If the number of units (b) is too large, the resulting gas separation will be inferior in practical strength, which is not preferable. The polyquinazolone polymer consisting of the unit () is insoluble in most organic solvents except for those exemplified as polymerization reaction solvents, and
It has extremely excellent chemical resistance. Furthermore, this polymer shows no weight loss even when heated to 450°C, and has extremely excellent heat resistance. The gas separation membrane according to the present invention can be produced by various methods, but usually, the polyquinazolone polymer is dissolved in a membrane-forming liquid solvent to form a uniform membrane-forming liquid, and this is mixed with an appropriate support base. After the material is cast and coated, the solvent is evaporated by heat treatment or heat treatment under reduced pressure to form a homogeneous film. In order to increase the gas permeation rate, the thinner the film is, the more preferable it is, but on the other hand, from the point of view of mechanical strength, the thicker the better, and from these points of view, the film thickness should be 0.05~
30μ is desirable. Therefore, the polymer concentration of the membrane forming solution is
The content should preferably be 13% by weight or less. The membrane forming solution solvent is dimethyl sulfoxide, N-methyl-2-pyrrolidone, N,
Aprotic polar organic solvents such as N-dimethylacetamide and N,N-dimethylformamide are preferred. The supporting base material for applying the dope is not particularly limited. Examples include plate members having smooth surfaces made of materials such as glass, stainless steel, aluminum, polyethylene, and polypropylene. The temperature at which the membrane forming solution is heated after being applied to the support substrate depends on the membrane forming solution solvent, but in the case of the above aprotic polar organic solvent, it is 80 to 140°C, preferably 100 to 120°C.
It is ℃. Particularly preferably, most of the solvent is evaporated in this temperature range, and then the temperature is raised to about 150 to 170°C to completely evaporate the solvent. If desired, the membrane and supporting substrate can then be immersed in water to peel the membrane from the substrate. The gas separation membrane of the present invention has excellent chemical resistance and heat resistance as described above, and has a large gas permeability coefficient and separation coefficient as seen in the examples described later, and also has high mechanical strength. Because of its excellent properties, it can be suitably used not only for oxygen enrichment but also for gas separation at high temperatures in _C1 chemistry. Examples of the present invention are listed below, but the present invention is not limited thereto. In the following examples, the gas permeability coefficient P is determined by the high vacuum method at 25°C, and the separation coefficient α is the gas permeability coefficient at 25°C/nitrogen permeability coefficient (P _N
2 ). Example 1 N-methyl-2- was placed in a flask equipped with a stirrer, a nitrogen gas introduction device, a reflux condenser with a reaction product water extraction device, and a jacket bath capable of heating up to a temperature of 250°C.
85 g of pyrrolidone was charged, and 0.39 g of phosphorus pentoxide was added and dissolved. Next, the structure below 18.39 g (0.055 mol) of bisoxazinone,
4,4′-diaminodiphenyl ether 8.81g
(0.044 mol) and 3.15 g (0.011 mol) of 4,4'-diaminodiphenylmethane-3,3'-dicarboxylic acid
was dissolved. 14g xylene as azeotropic dehydration solvent
was added and heated to 180°C under a nitrogen stream to reflux the xylene, and the reaction was carried out for 15 hours while continuously removing the reaction product water by azeotropy to obtain a viscous polymer solution. Ta. This polymer solution was poured into a large amount of water to coagulate and precipitate the polymer, which was then vigorously stirred and pulverized in water using a mixer. After separating this powder, it was vacuum dried at 60℃ for 10 hours, and the logarithmic viscosity was 0.71.
of polyquinazolone was obtained. This polyquinazolone
80 mol% bisquinazolone units and 20 mol% bisquinazolone units It has Next, 10g of this polyquinazolone was added to N-methyl-
After dissolving in 90g of 2-pyrrolidone, the average pore size is 10μ.
Pressure was applied using paper to remove foreign matter.
After casting this polymer solution onto a glass plate,
The solvent was removed by drying in a vacuum dryer at room temperature for 5 hours and then at 90°C for 10 hours. The polyquinazolone membrane was peeled off by immersion in water and vacuum dried at 80°C to obtain a membrane with a thickness of 13 μm. The gas permeability of this membrane is shown in the table.

[Table] Example 2 74.8 g of N-methyl-2-pyrrolidone was charged into a flask equipped with a stirrer, a nitrogen gas introduction device, a reflux device with a reaction product water removal device, and a jacket bath capable of heating to a temperature of 250°C. 600 mg (0.003 mol) of anhydrous stannous chloride was added as a polymerization catalyst, and 426 mg (0.003 mol) of phosphorus pentoxide was further added and dissolved as a dehydrating agent. Next, the same bisoxazinone as in Example 1
Add and dissolve 20.1 g (0.06 mol) and 12.0 g (0.06 mol) of 4,4'-diaminodiphenyl ether,
Furthermore, 15 g of xylene was added as an azeotropic solvent. The xylene was refluxed by heating to a temperature of 170 to 190° C. under a nitrogen stream, and polymerization was carried out while continuously removing reaction product water by azeotropy. start the reaction
After 10 hours, 15 g of NMP was added to dilute the reaction mixture, and the polymerization was continued for an additional 32 hours. The xylene was distilled off to obtain a viscous polyquinazolone polymer solution. The logarithmic viscosity of this polymer is 0.78 and consists of the following units: A gas separation membrane obtained from this polyquinazolone in the same manner as in Example 1 had an oxygen permeability coefficient of 2.1×10 ^-10 cc.
(STP)・cm/cm ²・sec・cmHg, and the separation coefficient was 5.0. Example 3 In Example 1, 8.72 g (0.044 mol) of 4,4'-diaminodiphenylmethane was used instead of 4,4'-diaminodiphenyl ether, and 4,4'-
1.67 g of 3,5-diaminobenzoic acid instead of diaminodiphenylmethane-3,3'-dicarboxylic acid
Polyquinazolone with a logarithmic viscosity of 0.59 was obtained in exactly the same manner except that (0.011 mol) was used. This polyquinazolone has 80 mol% bisquinazolone units and 20 mol% bisquinazolone units It has The oxygen permeability coefficient of the gas separation membrane made from this polyquinazolone in the same manner as in Example 1 was 9.8×10 ^-11
cc (STP)・cm/ ^cm2・sec・cmHg, separation factor is 5.1
It was hot. Example 4 In Example 2, 9.61 g (0.048 mol) of 4,4'-diaminodiphenyl ether and 3.89 g of piperazine bis(p-aminobenzoic acid amide) were used instead of 12 g of 4,4'-diaminodiphenyl ether.
A polyquinazolone with a logarithmic viscosity of 0.72 was obtained in exactly the same manner as in Example 2 except that (0.012 mol) was used.
This polyquinazolone contains 80 mol% of the above bisquinazolone units () and bisquinazolone units. It consists of 20 mol%. The oxygen permeability coefficient of the gas separation membrane made from this polyquinazolone in the same manner as in Example 1 was 2.4×10 ^-10
cc(STP)・cm/ ^cm2・sec・cmHg, separation factor is 4.7
It was hot.

Claims (1)

[Claims] 1. General formula (However, R ¹ is a tetravalent organic group, R ² is each independently an alkyl group or an aromatic group, and R ³ is (p+2)
A valent organic group, Z represents -COOH, -SO ₃ H or a metal salt thereof, and p is independently 0 or 1 for each unit.
Indicates an integer of ~4. ) A gas separation membrane made of a polyquinazolone polymer having bisquinazolone units represented by the following as repeating units. 2 R ¹ is and R ² is a methyl group or a phenyl group,
If p is 0 and R ³ is and/or The gas separation membrane according to claim 1, characterized in that: 3 R ¹ is and R ² is a methyl group or a phenyl group,
When p is 0, 1 or 2, and p is 0,
R ³ is and/or and when p is not 0, R ³ is [formula] [formula] or The gas separation membrane according to claim 1, characterized in that: