JP2020084155A - Resin composition, rein film and gas permeation film - Google Patents

Abstract

To provide a resin film containing polyimide and an ion liquid, and having excellent performances of gas permeation performance and strength as a film.SOLUTION: There is provided a resin composition containing a polyimide resin and an ion liquid, in which the polyimide resin has a constitutional unit (A) (following formula (1) and/or other structures with different aromatic ring substituent number), and a constitutional unit (B) (having an aromatic ring structure substituted by at least one sulfonic acid group) as essential constitutional units.SELECTED DRAWING: None

Description

The present disclosure relates to a resin composition, a resin film and a gas permeable film.

In recent years, attention has been paid to the selective absorption capacity of carbon dioxide contained in ionic liquids, and attempts to reduce the carbon dioxide emission in a factory that is a carbon dioxide emission source have been studied. As a part of such an attempt, a resin composition in which an ionic liquid is mixed with a matrix resin has been performed.

In addition, ionic liquids are also being studied as a material for batteries, and here also, forming a film as a resin composition in which an ionic liquid is mixed with a matrix resin is being studied.

Non-Patent Documents 1, 2, and 3 disclose films containing a polyimide resin and an ionic liquid. Here, a composition containing a polyimide resin having a sulfonic acid group and an ionic liquid is used to form a film by a solvent casting method, and the carbon dioxide permeability of this film is examined.

Patent Document 1 discloses that, in a polyimide resin, a structural unit containing fluorine is introduced into a polyimide resin having a sulfonic acid group. Patent Document 1 describes that the resin is used for measuring humidity.

China Application Publication No. 103865265

Polymer Journal (2017) 49, 671-676 Macromolecules 2018, 51 7112-7120 6th Ionic Liquid Discussion Session (October 27, 2015) Proceedings 50-51 "Application of ionic liquid/sulfonated polyimide composite membrane to CO2 separation technology"

An object of the present disclosure is to provide a resin film containing a polyimide and an ionic liquid, which has excellent performance in both gas permeability and strength as a film.

The present disclosure is a resin composition containing a polyimide resin and an ionic liquid,
The polyimide resin is a resin composition comprising the following structural unit (A) and the following structural unit (B) as essential structural units.
Structural unit (A):

(In the formula, Rf ₁ and Rf ₂ represent a substituent of an aromatic ring, and represent that any one of the four substitutable sites per aromatic ring is substituted with the substituent. Rf ₁ and Rf ₂ is the same or different and represents a fluorine atom or a fluorine-containing alkyl group having 1 to 8 carbon atoms.
The C ₁ group represents an aromatic ring structure, and the C ₁ group forms a ring of 5 or 6 atoms with each adjacent imide group. )
And/or

(In the formula, Rf ₃ represents a substituent on the aromatic ring, and any one of the four substitutable sites on the aromatic ring is substituted with the substituent. Rf ₃ represents a fluorine atom or a carbon number. It represents 1 to 8 fluorine-containing alkyl groups.
The C ₂ group represents an aromatic ring structure, and each C ₂ group forms a ring of 5 or 6 atoms with the adjacent imide group. )
Structural unit (B):

(The C ₃ group represents an aromatic ring structure, and the C ₃ group forms a ring of 5 or 6 atoms together with the adjacent imide group.)
Ar is a structural unit having an aromatic ring structure substituted with at least one sulfonic acid group.
X is hydrogen or a cationic species.
n represents an integer of 1 to 4.
(C _{1 to} C ₃ in the general formulas (1) to (3) may be the same or different)

The resin composition according to claim 1, wherein the mixing ratio of the polyimide resin and the ionic liquid is ionic liquid/(total amount of ionic liquid and polyimide resin) of 50% by weight or more.

The structural unit (A) is

It is preferable that the structure is represented by
The above structural unit (A) is

The structure represented by is preferable.
The above structural unit (B) is

で表される構造であることが好ましい。
上記構成単位（Ｂ）は、

The structure represented by is preferable.
The above structural unit (B) is

The structure represented by is preferable.
The polyimide resin preferably has a structural unit A/(structural unit A+structural unit B) of 20 to 50% (on a molar basis).

The present disclosure is also a resin film characterized by comprising the resin composition described above.
The present disclosure is a resin film containing a fluorinated polyimide resin and an ionic liquid,
Tensile elastic modulus is 10 MPa or more, and
It is also a resin film having a breaking stress of 10 MPa or more in a tensile test.
The present disclosure is also a gas permeable film characterized by being formed of the above resin film.
The gas permeable membrane is preferably a carbon dioxide selective permeable membrane.

The resin composition of the present disclosure and the film made of the resin composition have significantly improved strength while maintaining gas permeability.

The image figure of the measuring method used in the gas permeation test in an Example is shown.

Hereinafter, the present disclosure will be described in detail.
The present disclosure partially uses the structural unit A containing a fluorine atom in a composition containing a polyimide and an ionic liquid. As a result, the membrane strength can be increased while maintaining the selective carbon dioxide permeability. In particular, when an ionic liquid that is a liquid component is blended, the strength of the film generally tends to decrease, but in the case of a resin composition using a polyimide resin in which the structural units A and B are essential, Since the strength of the membrane is not significantly reduced, it is expected to be suitable for various applications.

Although the action of obtaining such an effect is not clear, it is presumed that the action of adding a fluorine moiety imparts rigidity, enhances the binding force, and increases the thermal and mechanical strength.

(Polyimide resin)
The polyimide resin used in the present disclosure has the structural unit A and the structural unit B described above.
Hereinafter, each of these structural units will be described.

(Structural unit A)
The structural unit A is

(In the formula, Rf ₁ and Rf ₂ represent a substituent of an aromatic ring, and represent that any one of the four substitutable sites per aromatic ring is substituted with the substituent. Rf ₁ and Rf ₂ is the same or different and represents a fluorine atom or a fluorine-containing alkyl group having 1 to 8 carbon atoms.
The C ₁ group represents an aromatic ring structure, and the C ₁ group forms a ring of 5 or 6 atoms with each adjacent imide group. )
And/or

(In the formula, Rf ₃ represents a substituent on the aromatic ring, and any one of the four substitutable sites on the aromatic ring is substituted with the substituent. Rf ₃ represents a fluorine atom or a carbon number. It represents 1 to 8 fluorine-containing alkyl groups.
The C ₂ group represents an aromatic ring structure, and each C ₂ group forms a ring of 5 or 6 atoms with the adjacent imide group. )
The structure is represented by.

The structural unit A further comprises

And/or

Unit derived from aromatic diamine represented by

It is composed of a unit derived from an aromatic acid anhydride represented by
These units will be described individually.

(Unit derived from fluorine-containing aromatic diamine)
In the present disclosure, such a unit derived from a fluorine-containing aromatic diamine is presumed to contribute to the strength based on the action as described above.
In the above formulas (1) and (4), Rf ₁ and Rf ₂ are the same or different and each represents a fluorine atom or a fluorine-containing alkyl group having 1 to 8 carbon atoms. Among these, Rf ₁ and Rf ₂ are preferably a fluorine atom and a C 1 to C 4 fluorine-containing alkyl group, and more preferably a fluorine atom and a C 1 to C 3 fluorine-containing alkyl group. Specifically, a fluorine atom, fluoromethyl group, difluoromethyl group, trifluoromethyl _{group, HCF 2 CF 2 -, CF} 3 CF 2 -, CF 3 CH 2 -, CF 3 CF 2 CF 2 CF 2 -, CF ₃ CF ₂ CF ₂ CH ₂ - it is preferred, a fluorine atom, fluoromethyl group, difluoromethyl group, trifluoromethyl _{group, CF 3 CF 2 -, HCF} 2 CF 2 - is more preferable. Particularly preferred is a trifluoromethyl group.

As the fluorinated diamine represented by the above formula (4), specifically, fluorinated biphenyldiamine is mentioned as a preferable example. Among these, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 2,2'-bis(hexafluoroethyl)-4,4'-diaminobiphenyl are more preferable, and 2,2' Particularly preferred is'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

In the above formulas (2) and (5), Rf ₃ represents a fluorine atom or a fluorine-containing alkyl group having 1 to 8 carbon atoms. Among these, Rf ₁ and Rf ₂ are preferably a fluorine atom and a C 1 to C 4 fluorine-containing alkyl group, and more preferably a fluorine atom and a C 1 to C 3 fluorine-containing alkyl group. Specifically, a fluorine atom, fluoromethyl group, difluoromethyl group, trifluoromethyl _{group, HCF 2 CF 2 -, CF} 3 CF 2 -, CF 3 CH 2 -, CF 3 CF 2 CF 2 CF 2 -, CF ₃ CF ₂ CF ₂ CH ₂ - it is preferred, a fluorine atom, fluoromethyl group, difluoromethyl group, trifluoromethyl _{group, HCF 2 CF 2 -, CF} 3 CF 2 - is more preferable. Particularly preferred is a trifluoromethyl group.

Specific examples of suitable fluorinated diamines represented by the above formula (5) include 2-trifluoromethyldiamine and 2-hexafluoroethyldiamine. Among these, 2-trifluoromethyldiamine is particularly preferable.

(Unit derived from aromatic acid anhydride)
As the unit derived from the above-mentioned aromatic acid anhydride, a diacid anhydride generally used in polyimide resins can be used. In the general formula (1), C ₁ is described, and in the general formula (2), C ₂ is described, but these essentially have the same structure. Therefore, in the present specification, both of them may be referred to as C as a structure that collectively means.
The unit derived from an aromatic acid anhydride is specifically a structure derived from an aromatic acid anhydride having the following structure.

In the formula, the C group represents an aromatic ring structure, and the C group forms a ring of 5 or 6 atoms together with the adjacent imide group.
The phrase "C group forms a ring of 5 or 6 atoms with adjacent imide groups" specifically means, for example, the following structures.

In the above formula, C is exemplified as a benzene ring or a naphthalene ring, but other ring structures may be used as long as they are aromatic rings.

In the above formulas (1) and (2), C ₁ and C ₂ are, more specifically,
(A) one aromatic ring optionally substituted by one or two substituents selected from an alkyl group having 10 or less carbon atoms, an alkoxy group and a halogen atom,
(B) Several aromas which may be substituted by one or more substituents selected from an alkyl group having 10 or less carbon atoms, an alkoxy group and a halogen atom, which are bonded by a single bond or a divalent group. Tribal ring,
(C) a polycyclic aromatic group in which two or more aromatic rings which may be substituted with one or two substituents selected from an alkyl group having 10 or less carbon atoms, an alkoxy group and a halogen atom are condensed. Can be mentioned.

The above (A) represents a monocyclic aromatic ring such as benzene, thiophene, pyridine, furan, quinoline, quinoxaline, and isobenzofuran.

The above (B) has a structure in which a plurality of aromatic rings are bound by a single bond or a divalent group such as a biphenyl group and a bisphenol group. Here, the divalent group that binds a plurality of aromatic rings is not particularly limited, and may be, for example, one or more halogen and/or one or more hydroxyl group selected from: -F, Cl, Br and I. A divalent group derived from a linear or branched alkyl group having 10 or less carbon atoms (eg, alkylidene or alkylene group), which may be substituted on the same carbon, and the divalent group is perfluoro. It may be a divalent group derived from a fluorinated alkyl group such as a perfluorinated alkylene.

The above (C) represents a structure having a condensed carbon polycyclic group. As such a condensed carbon polycyclic group, for example, a group containing 2-5 benzene rings selected from naphthalene, phenanthrene, coronene, perylene and the like can be used.
Furthermore, it may be a condensed heterocycle having a heterocyclic ring having aromaticity such as thiophene, pyridine, furan, quinoline, quinoxaline, or isobenzofuran as a part of the constitutional unit.

In any of the structures (A), (B), and (C) above, the position of the ring not substituted by an acid anhydride group is an alkyl group having 10 or less carbon atoms (eg, methyl, ethyl, isopropyl, etc.) and It may be substituted with one or more substituents selected from an alkoxy group and a halogen atom (F, Cl, Br, I).

Structures that can be specifically used as C ₁ and C _{2 in} the structure of such an acid anhydride are shown below.

Among these, the general formula

で表される、１，４，５，８−ナフタレンテトラカルボン酸ジ無水物に由来する骨格であることが最も好ましい。このような構成単位を使用したポリイミド樹脂は、強度において特に優れるという点で特に好ましいものである。

Most preferably, it is a skeleton derived from 1,4,5,8-naphthalenetetracarboxylic dianhydride. A polyimide resin using such a constitutional unit is particularly preferable because it is particularly excellent in strength.

(Structural unit B)
The structural unit B is

(The C ₃ group represents an aromatic ring structure, and the C ₃ group forms a ring of 5 or 6 atoms together with the adjacent imide group.
Ar is a structural unit having an aromatic ring structure substituted with at least one sulfonic acid group.
X is hydrogen or a cationic species.
n represents an integer of 1 to 4).

The structure is

で表されるスルホン酸基を有する芳香族ジアミンに由来するユニット及び

And a unit derived from an aromatic diamine having a sulfonic acid group represented by

で表される芳香族酸無水物に由来するユニットからなるものである。
これらのうち、芳香族酸無水物に由来するユニットは、上述した構成単位Ａにおいて詳述したものと同様のものを使用することができる。よって、以下に、スルホン酸基含有芳香族ジアミンに由来するユニットについて詳述する。

It is composed of a unit derived from an aromatic acid anhydride represented by
Among these, as the unit derived from the aromatic acid anhydride, the same units as those described in detail in the structural unit A can be used. Therefore, the unit derived from the sulfonic acid group-containing aromatic diamine will be described in detail below.

(Unit derived from sulfonic acid group-containing aromatic diamine)
The unit represented by the general formula (7) has a sulfonic acid group and is a structural unit for increasing the affinity with the ionic liquid and obtaining a stable composition.

In the formula, Ar is a functional group having an aromatic group. The aromatic group may be substituted with, for example, an alkyl or alkoxy group having 10 or less carbon atoms, such as methyl, ethyl, isopropyl, butyl, anisole, etc., and one or more substituents selected from halogen atoms, meta or A para-bonded divalent benzene ring; or several, which may be substituted by one or more substituents selected from alkyl and alkoxy groups having 10 or less carbon atoms and halogen atoms bonded by a single bond or a divalent group Benzene ring, for example, a ring of 2-5.

The divalent group has, for example, the same carbon atom, the number of carbon atoms which may be substituted by one or more halogen and/or one or more hydroxy group selected from F, Cl, Br and I. It may be a divalent group derived from a linear or branched alkyl group having 10 or less (for example, alkylidene or alkylene group). It is further preferred that the above-mentioned derivatized groups are perfluorinated alkyl groups, for example divalent groups derived from perfluorinated alkylenes.

Ar may also represent an alkyl or alkoxy group having 10 or less carbon atoms and a condensed carbon polycyclic group which may be substituted with one or more substituents selected from halogen atoms. Such Ar is selected from naphthalene, phenanthrene, coronene, perylene and the like.
Ar may represent a heterocyclic ring or a condensed heterocyclic ring having aromaticity such as thiophene, pyrazine, pyridine, furan, quinoline, quinoxaline, and isobenzofuran, and the heterocyclic ring may be an alkyl group and 1-10 C Optionally substituted with one or more substituents selected from the group consisting of an alkoxy group having, for example, methyl, ethyl, isopropylmethoxy, and a halogen atom (F, Cl, Br, I).

In the present disclosure, at least one of the rings of Ar, such as a benzene ring or a polyphenyl ring or another ring, is further substituted with one or more sulphonic acid groups.
The number of substituted sulfonic acid group is represented by _{n, Ar- (SO 3 X)} n represents the sulfonic acid group is n pieces present in the Ar group described above. The n is preferably 1 to 4.
The —SO ₃ X is preferably one directly bonded to an aromatic ring.
The most preferred Ar structure is that of the biphenyl-disulfonic acid group.

In addition, X in the formula may be hydrogen or any cation species. The cation species are not particularly limited, but quaternary ammonium ions are particularly preferable. The use of such a quaternary ammonium ion is preferable in that the affinity with the ionic liquid can be increased and the compounding amount of the ionic liquid can be increased. More specifically, as the quaternary ammonium ion, the same cations as those of the ionic liquid described in detail below can be mentioned. Moreover, all such X may be substituted by the above-mentioned cation species, or only a part thereof may be substituted by the cation species. Further, it may be substituted with two or more kinds of cations.

More specific examples of the above-described structure will be given below. In addition, in this indication, the unit derived from the aromatic diamine which has a sulfonic acid group is not limited to the following structural units.

Of these, the most preferable Ar structure is a biphenyl-disulfonic acid group represented by the following formula. Such compounds are preferable from the viewpoint of increasing the affinity with ionic liquids, particularly cations.

As described above, the polyimide resin used in the present disclosure requires three structural units, namely, a fluorine-containing aromatic diamine, an aromatic acid anhydride, and a sulfonic acid group-containing aromatic diamine, but each has a single unit. Of these constituent units, or one or more of these constituent units may use two or more components in combination. Further, C _{1 to} C ₃ represented by the above general formula may be the same or different. Further, two or more kinds of structural units having different C ₁ , C ₂ , and C ₃ may be used in combination.

The polyimide resin used in the present disclosure has the structural unit (A)

And the structural unit (B) is

The structure represented by is more preferable.

The polyimide resin used in the present disclosure has the structural unit (A)

The structural unit (B) is represented by

Most preferably, the structure is Such a polymer is particularly preferable in that it is a good polymer that is well balanced in terms of both strength and affinity with an ionic liquid.

(Structural units other than structural unit A and structural unit B)
The polyimide resin used in the present disclosure may be composed of only the structural unit A and the structural unit B described above, or may partially include other structural units.
The above-mentioned other structural units are not particularly limited, and examples thereof include structures generally known in polyimide resins. Specifically, an imide structural unit having an aromatic diamine such as paraphenylenediamine, 1,3-bis(4-aminophenoxy)benzene, 4,4′-diaminodiphenyl ether, and 3,4′-diaminodiphenyl ether as a unit. Can be mentioned.

(Other properties of polyimide resin)
The composition ratio of the structural unit A and the structural unit B is not particularly limited in the polyimide resin used in the present disclosure, but the structural unit A/(the structural unit A+the structural unit B) is 20 to 50% (mol (Converted) is preferable. If the structural unit A is less than 10%, the strength may be insufficiently improved, and if the structural unit A exceeds 70%, the performance as a carbon dioxide selective permeable membrane may be insufficient.
The lower limit is more preferably 20%. The upper limit is more preferably 50%.

In addition, the above-mentioned “other structural unit” is preferably a ratio such that (other structural unit)/(structural unit A+structural unit B+other structural unit) is 10% or less (on a molar basis). .. If the content of the other structural unit exceeds 10%, sufficient physical properties may not be obtained in terms of affinity with the ionic liquid and strength.

(Method for producing polyimide resin)
The polyimide resin in the present disclosure includes a fluorinated diamine represented by the above formula (4) and/or a fluorinated diamine represented by the above formula (5) and a sulfonic acid group-containing diamine represented by the above formula (7). And the acid anhydride represented by the above formula (6) and, if necessary, other diamine or acid anhydride as a raw material monomer to perform a ring-opening polyaddition reaction to produce a polyamic acid, and the polyamide It can be obtained by subjecting an acid to a cyclodehydration reaction.

The above ring-opening polyaddition reaction can be carried out by a commonly used method, and examples thereof include a method in which the above raw material monomers are stirred in a solvent to carry out the reaction.

Examples of the solvent include amides such as N-methylpyrrolidone, dimethylacetamide and dimethylformamide; sulfoxides such as dimethylsulfoxide; esters such as γ-butyrolactone, butyl acetate, ethyl acetate and ethyl lactate; methyl ethyl ketone and methyl isobutyl. Ketones, acetone, ketones such as cyclohexanone; and the like can be used. Among these, a solvent in which the total of ketones and/or esters accounts for 40% by mass or more of the total solvent is preferable, and more preferably a solvent in which the total of ketones and/or esters accounts for 50% by mass or more of the total solvent. And more preferably a solvent in which the total amount of ketones and/or esters accounts for 75% by mass or more of the total solvent.

The ring-closing polyaddition reaction using the above monomers may be carried out during the reaction while substituting with an inert gas, preferably nitrogen gas. The reaction temperature and the reaction time can be appropriately set, but are, for example, 0 to 150° C., preferably room temperature (25° C.) to 100° C., and 2 to 24 hours, preferably 2 to 12 hours. Can be time.

The dehydration cyclization reaction can be carried out by a commonly used method, for example, a method of heat-treating a polyamic acid obtained by the above ring-opening polyaddition reaction, a polyamic acid obtained by the above ring-opening polyaddition reaction. And a method of chemically treating.

As a method of heat-treating the polyamic acid, specifically, the polyamic acid is reacted in an atmosphere of an inert gas at a reaction temperature of 20 to 300° C., preferably 50 to 200° C. for 1 to 48 hours, preferably 2 Examples include a method of heating for about 24 hours.
Examples of the inert gas include argon gas, helium gas, and nitrogen gas. At this time, a dehydrating agent such as phosphoric acid may be used.

Specific examples of the method of chemically treating the polyamic acid include a method of treating the polyamic acid with a dehydrating agent and an imidizing agent. The method of treatment with the imidizing agent can be carried out by a commonly used method.
Examples of the treatment method include a method using acetic anhydride as a dehydrating agent and pyridine as an imidizing agent.

The higher the imidization ratio, the more preferable, and the upper limit is 100%. If the imidization ratio is low, the relative dielectric constant may decrease, so the lower limit is preferably 70%. The imidization ratio can be measured by IR analysis.

(Ionic liquid)
In the present disclosure, an ionic liquid is also called a room temperature molten salt, is a compound that is composed of only ions, is a liquid in a wide temperature range including room temperature, and is non-volatile and non-flammable. There is no limitation on the type of ionic liquid contained in the resin composition of the present disclosure, and known ones can be used.
The specific ionic liquid is illustrated below.

Examples of the cation species constituting the ionic liquid include primary (R ₁ NH ₃ ⁺ ), secondary (R ₁ R ₂ NH ₂ ⁺ ), tertiary (R ₁ R ₂ R ₃ NH ⁺ ), Quaternary (R ₁ R ₂ R ₃ R ₄ N ⁺ ) chain ammonium cation (wherein R ₁ , R ₂ , R ₃ , and R ₄ are each independently a straight chain or branched chain having 1 to 15 carbon atoms) Alkyl group, or a linear or branched alkyl group having 1 to 15 carbon atoms in the side chain and having 1 to 15 carbon atoms, or a phenyl group) and a cyclic ammonium cation can be used. Examples of the cyclic ammonium cation include oxazolium, thiazolium, imidazolium, pyrazolium, pyrrolinium, flazanium, triazolium, pyrrolidinium, imidazolidinium, pyrazolidinium, pyrrolinium, imidazolinium, pyrazolinium, pyrazinium, pyrimidinium, pyridazinium, piperidinium, piperidinium, piperazinium, Included are lithium and carbazolium. As another cation, a chain phosphonium cation (R ₅ R ₆ R ₇ P ⁺ and R ₅ R ₆ R ₇ R ₈ P ⁺ ) and a chain sulfonium cation (R ₉ R ₁₀ R ₁₁ S ⁺ ) (in the formula) , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , and R ₁₁ are each independently a linear or branched alkyl group having 1 to 12 carbon atoms or a phenyl group) and a cyclic sulfonium cation. Is mentioned. Examples of cyclic sulfonium cations include thiophenium, thiazolinium and thiopyranium.

As the anion species constituting the ionic liquid, inorganic acid ions such as phosphoric acid, sulfuric acid and carboxylic acid, and fluorine ions can be used. Various combinations of cations and anions are possible.

Here, as the fluorine-based anion, tetrafluoroborate (BF ₄ ⁻ ), hexafluoroborate (BF ₆ ⁻ ), hexafluorophosphate (PF ₆ ⁻ ), hexafluoroarsenate (AsF ₆ ⁻ ), trifluoromethanesulfonate ( CF ₃ SO ₃ ^-), bis (fluorosulfonyl) imide ^{_{((FSO 2) 2 N -}} ), bis (trifluoromethanesulfonyl) imide _{((CF 3 SO 2) 2} N -), bis (trifluoro ethane sulfonyl) imide _{((CF 3 CF 2 SO 2} ) 2 N -), tris (trifluoromethanesulfonyl _{methide) ((CF 3 SO 2)} 3 C -) can be mentioned.

Particularly suitable ionic liquids used in the present disclosure are 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C ₂ mim][NTf ₂ ]), 1-butyl 3-methylimidazo. Lithium hexafluorophosphate ([C ₄ mim][PF ₆ ]), 1-ethyl-3-methylimidazolium tetrafluoroborate ([C ₂ mim][BF ₄ ]), and diethylmethylammonium trifluoromethanesulfonate ([[ DEMA][TfO]).
Also, two or more kinds of ionic liquids may be used in combination.

In the resin composition of the present disclosure, the mixing ratio of the polyimide resin and the ionic liquid is preferably ionic liquid/(total amount of ionic liquid and polyimide resin) of 50 to 75% (weight basis). It is preferable that the content is within the range because carbon dioxide can be separated and the strength as a film can be obtained.

(Other ingredients)
The resin composition of the present disclosure may be a composition composed only of the ionic liquid and the polyimide resin described above, or may be one to which other additives are added within a range that does not adversely affect the physical properties.

(Resin composition)
The resin composition in the present disclosure is not limited to the form and shape thereof as long as it contains the above-described polyimide resin and ionic liquid, and not only the shape of the resin film described in detail below, but also other than the film. Of any form, such as those molded into the shape of, a layer that constitutes one layer of the laminate, a solution state in which an ionic liquid and a polyimide resin are dissolved in a solvent for molding into various articles, and the like. Is included.

(Resin film)
The resin film of the present disclosure is also a resin film in which the above resin composition is formed into a film shape. That is, the polyimide resin and the ionic liquid described above are mixed and molded into a film. The thickness of the film is preferably in the range of 1 to 100 μm.

The method of molding into such a film shape is not particularly limited, but the film can be molded by, for example, a casting method. That is, it can be obtained by a method of preparing a resin composition in a solution state in which an ionic liquid and a polyimide resin are dissolved in a solvent, applying the composition on an arbitrary substrate, and drying the composition to remove the solvent.

The resin composition used to form the resin film is prepared by mixing an ionic liquid and a polyimide resin with a solvent, and a method of synthesizing the polyimide resin in the presence of the ionic liquid and the solvent. However, any method may be used.

The solvent is not particularly limited as long as it is a solvent that can be mixed with both the ionic liquid and the polyimide resin, and examples thereof include m-cresol.

The present disclosure is also a resin film containing a fluorine-containing polyimide resin and an ionic liquid, which has a tensile elastic modulus of 10 MPa or more and a breaking stress by a tensile test of 10 MPa or more.
That is, a resin film satisfying these physical properties is novel. The inventors have found a new resin film satisfying such a property, and have found that such a resin film has an unprecedented excellent performance.
The resin film having these physical properties has excellent strength and also has excellent carbon dioxide selective permeability. Such a resin film having excellent strength and high elastic modulus is expected to be widely used in many fields. Further, since it has fluorine in the resin structure, it has excellent strength even if it contains an ionic liquid.

In the resin film satisfying the specific physical properties, it is preferable that the fluorine-containing polyimide resin has the structural unit (A). Further, the ratio of ionic liquid/(total amount of ionic liquid and fluorine-containing polyimide resin) is preferably 50 to 75% (weight basis).

The tensile elastic modulus and the breaking stress in the disclosure mean values measured by the methods described in the examples.

(Gas permeable membrane)
The resin film of the present disclosure has excellent performance of being capable of selectively permeating carbon dioxide. Therefore, it can be used for the purpose of removing exhausted carbon dioxide in a factory that generates a large amount of carbon dioxide.

That is, in the carbon dioxide removing means for such purpose, the resin film can be used as a main member for removing carbon dioxide.

The method of removing carbon dioxide using the gas permeable membrane of the present disclosure is not particularly limited, but, for example, while passing a gas, only carbon dioxide is permeated through the membrane, and carbon dioxide is discharged to the opposite side of the membrane. Examples include a method of removing carbon and recovering air having a reduced carbon dioxide content.

The gas permeable membrane of the present disclosure preferably has a carbon dioxide permeability coefficient P _CO2 of 300 Barrer or more when the permeability is measured by the method of the example. Having a transmittance within the above range is preferable in that carbon dioxide can be suitably transmitted.

In the gas permeable membrane of the present disclosure, the CO ₂ /N ₂ separation coefficient α _Co2/N2 when the transmittance is measured by the method of the example is preferably 30 or more. Having a separation coefficient within the above range is preferable in that the function of selectively permeating carbon dioxide is enhanced.

The gas permeable membrane of the present disclosure can also be used as a gas permeable membrane for reducing carbon dioxide in an air conditioner. That is, the air conditioner adjusts the temperature, humidity, etc. in the closed space, but it is necessary to prevent the carbon dioxide in the space from becoming highly concentrated due to the carbon dioxide generated by human breathing or the like.

In order to prevent the concentration of carbon dioxide from increasing, it has been necessary for the air conditioner to have a ventilation function. However, a large proportion of the energy consumed in air conditioning equipment has been consumed due to the load due to ventilation. Therefore, the gas permeable membrane of the present invention can be used for the purpose of reducing the load due to such ventilation.

That is, the gas permeable membrane as described above can be installed in an air conditioner and used as a carbon dioxide reduction device. When the gas permeable membrane of the present disclosure is installed in an air conditioner, it can be installed in any air conditioner such as an air conditioner in a building such as an office building, an air conditioner in a vehicle such as a car or a railroad, an air conditioner in an aircraft. ..

Hereinafter, the present disclosure will be specifically described based on Examples. First, the raw materials used will be described below.
・1-Propylimidazole (1-propylimidazole (C ₃ imH))
The product purchased from Tokyo Chemical Industry was distilled under reduced pressure and used.
*2,2-benzidine disulfonic acid (2,2-benzidine disulfide acid (BDSA))
Triethylamine was added to the product purchased from Tokyo Kasei Kogyo Co., Ltd., dissolved in water, a precipitate was obtained using 1 MH ₂ SO ₄ , filtered, and purified.
-Bis[4-(3-aminophenyl)-phenyl]sulfonate (Bis[4-(3-aminophenoxy)-phenyl]sulfonate (3BAPPS))
The product recrystallized from ethanol was used.
・2,2-Bis(trifluoromethyl)benzidine (2,2-Bis(trifluoromethyl)benzidine (TFMB))
Daikin Industries Ltd. was used as it was.
*1,4,5,8-naphthalene tetracarboxylic acid dianhydride (1,4,5,8-Naphthalene-tetracarboxylicdian hydride (NTDA))
The product purchased from Sigma-Aldrich was purified from N,N-dimethylsulfoamide (N,N-dimethylformamide (DMF)) and used.
・Benzoic acid
The one purchased from Tokyo Chemical Industry was used as it was.
・M-cresol
The product purchased from Kanto Kagaku was purified and used.

(Comparative Synthesis Example 1)
According to the following references, BDSA and 3BAPPS (BDSA:3BAPPS=4:1) were synthesized in two steps: polyaddition with an equal amount of NTDA and chemical imidization reaction.
Scheme 1 shows a synthetic scheme of a sulfone-based polyimide resin. A three-necked flask was placed under an Ar atmosphere, 2.00 g (5.83 mmol) of BDSA, 10 ml of purified m-cresol, and about 1.7 ml (15 mmol) of 1-propylimidazole (C ₃ imH) were added, and the mixture was stirred at 50°C. Then, BDSA was dissolved. Next, 1.95 g (7.27 mmol) of NTDA and 0.629 g (1.45 mmol) of 3BAPPS were added while washing with m-cresol, and stirred at 100° C. to completely dissolve them. After confirming the dissolution, the temperature was raised to 175° C. and the mixture was stirred for 21 hours to carry out a polyaddition reaction. Thereafter, 2.13 g (17.4 mmol) of benzoic acid was added, and the mixture was stirred at 195° C. for ₃ hours to carry out a dehydration ring-closing reaction to synthesize a C ₃ imH type sulfonated polyimide in which a cation of a sulfonic acid group was present. The precipitate was reprecipitated using acetone, washed with acetone three times, and vacuum dried at 60° C. for 48 hours to obtain brown C ₃ imH type sulfone-based polyimide resin (about 2.63 g). The structure was identified by ¹ H-NMR (DMSO-d ₆ ) and the molecular weight was estimated by gel permeation chromatography (GPC). As a result, the number average molecular weight Mn was 86000.

For GPC, a GPC device manufactured by Shimadzu Corporation was used, and measurement was performed using a column: CTO-20A (manufactured by Shimadzu Corporation), a developing solvent DMF, and a polystyrene standard.

(Synthesis example 1)
According to the following references, BDSA and TFMB (BDSA:TFMB=4:1) were synthesized in two steps: polyaddition with an equal amount of NTDA and chemical imidization reaction.
The following Scheme 2 shows the synthetic scheme of Example 1. The three-necked flask was placed under an Ar atmosphere, 2.43 g (7.04 mmol) of BDSA and 10 ml of purified m-cresol, and about 2 ml (18 mmol) of 1-propylimidazole (C ₃ imH) were added, and the mixture was stirred at 50° C. BDSA was dissolved. Next, 2.40 g (8.95 mmol) of NTDA and 0.567 g (1.77 mmol) of TFMB were added while washing with m-cresol, and stirred at 100° C. to completely dissolve them. After confirming the dissolution, the temperature was raised to 175° C. and the mixture was stirred for 21 hours to carry out a polyaddition reaction. Thereafter, 2.65 g (21.7 mmol) of benzoic acid was added, and the mixture was stirred at 195° C. for ₃ hours to carry out a dehydration ring closure reaction to synthesize C ₃ imH type sulfonated polyimide (SPI) having a cation of a sulfonic acid group. The precipitate was reprecipitated using acetone, washed with acetone three times, and then vacuum dried at 60° C. for 48 hours to obtain brown C ₃ imH type sulfonated polyimide (about 4.01 g). The structure was identified by ¹ H-NMR (DMSO-d ₆ ) and the molecular weight was estimated by gel permeation chromatography (GPC). As a result, the number average molecular weight was 87,000.

Example 1, Comparative Example 1
(Preparation of ionic liquid/polyimide resin composite film)
· The ionic liquid was used _{([C 2 mim] [NTf} 2]). Specifically, the product purchased from Tokyo Chemical Industry was used as it was.
[C ₂ mim][NTf ₂ ] is a compound having a chemical structure represented by the following general formula.

Membranes were prepared according to the references below. [C ₂ mim][NTf ₂ ] and the polyimide resin synthesized in Comparative Synthesis Example 1 or Synthesis Example 1 were dissolved in a cosolvent, m-cresol, at 80°C, cast on a glass petri dish, and dried at 60°C. A C ₂ mim][NTf ₂ ]/sulfone-based polyimide resin composite film (Comparative Example 1) and a [C ₂ mim][NTf ₂ ]/fluorine-based polyimide resin composite film (Example 1) were obtained. A solution was prepared so that the amount of the ionic liquid supported was 0.75 wt% with respect to the polyimide resin, and a composite film was produced. The film thickness of the film of Example 1 was 90.2 μm and that of the film of Comparative Example 1 was 85.1 μm.

The surface state of the obtained composite film was confirmed by touching the finger after manufacturing. As a result, it was confirmed that the exudation of the liquid did not occur. From this, it was confirmed that the film was formed by the composition in which the resin and the ionic liquid were uniformly mixed.

The obtained composite film was evaluated for physical properties based on the following criteria. The results are shown in Table 1 below.
(Tensile test)
(1) Equipment EZ-LX 100N manufactured by Shimadzu Corporation was used.
(2) Sample Preparation The polyimide resin composite film having the ionic liquid-carrying amount of 75 wt% produced in Comparative Example 1 and Example 1 was used. As the measurement sample, a JIS standard No. 7 dumbbell-shaped sample piece was used.
(3) Measurement conditions A tensile test was conducted at a test force of 10 N, a stroke of 1 mm/sec, and room temperature. Breaking stress, breaking strain, elastic modulus, breaking energy per unit volume were obtained and evaluated. The results are shown in Tables 1, 2, and 3.

The same analysis was performed on the membranes containing no ionic liquid obtained in the above-mentioned examples. The results are shown in Table 2.

From the results shown in Table 1 above, it was revealed that the resin film of Example 1 had excellent properties in strength, elastic modulus, etc., as compared with the resin film of Comparative Example 1.

(Gas permeation test)
(1) Apparatus GTR-10XFKS manufactured by GTR Tech Co., Ltd. was used as a gas permeability measuring apparatus, and gas chromatography G2700T manufactured by Yanaco was used as a detector.
(2) Sample Preparation The polyimide resin composite film having the ionic liquid loading of 75 wt% produced in Comparative Example 1 and Example 1 was used.
(3) Measurement conditions Measurement 30 & ORDM in each of the composite membrane; were each gas permeation test for a single gas N ₂ and CO ₂ at equal pressure method at a temperature of C. In all measurements, the pressure of the sample gas and the carrier gas was 76 cmHg (1 atm), and the area of the gas permeable membrane was 9.62 cm ² . The sample gas flow rate was 30 ml/min, the carrier gas flow rate was 50 ml/min, and He was used as the carrier gas. The measurement was performed 6 times for one film at the same temperature, and the average value was used as the measurement result. FIG. 1 shows a gas permeation system using the isobaric method. The evaluation results were obtained by calculating the carbon dioxide permeability coefficient (Barr) P _CO2 :380 and the nitrogen permeability coefficient (Barrer) P _N2 :120 CO ₂ /N ₂ separation coefficient α _Co2/N2 :31, respectively. ..

From the results shown in Table 3, it was revealed that the membrane of Example 1 has the same function as the carbon dioxide selective permeable membrane as that of the conventional membrane of Comparative Example 1.
Further, from the results of Tables 1 and 2, the film of Example 1 has a significantly superior effect as compared with the film of Comparative Example 1 in terms of elastic modulus and strength.

The following documents are cited as reference documents. In the examples, the membranes were prepared based on the method described in the literature.
References: Lee, S.-Y., Ogawa, A., Kanno, M., Nakamoto, H., Yasuda, T. & Watanabe, M. Nonhumidified intermediate temperature fuel cells using protic ionic liquids. J. Am Chem. Soc. 132, 9764 &# 8211;9773 (2010).
While the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

INDUSTRIAL APPLICABILITY The resin composition and the resin film of the present disclosure can be used as a carbon dioxide permeable film in fields requiring suppression of carbon dioxide emission and in air conditioning equipment.

1 Resin membrane 2 Gas chromatography (GC)
3 Mass flow controller (MFC)

Claims (11)

A resin composition containing a polyimide resin and an ionic liquid,
A polyimide resin is a resin composition comprising the following structural unit (A) and the following structural unit (B) as essential structural units.
Structural unit (A):

(In the formula, Rf ₁ and Rf ₂ represent a substituent of an aromatic ring, and represent that any one of the four substitutable sites per aromatic ring is substituted with the substituent. Rf ₁ and Rf ₂ is the same or different and represents a fluorine atom or a fluorine-containing alkyl group having 1 to 8 carbon atoms.
The C ₁ group represents an aromatic ring structure, and the C ₁ group forms a ring of 5 or 6 atoms with each adjacent imide group. )
And/or

(In the formula, Rf ₃ represents a substituent on the aromatic ring, and any one of the four substitutable sites on the aromatic ring is substituted with the substituent. Rf ₃ represents a fluorine atom or a carbon number. It represents 1 to 8 fluorine-containing alkyl groups.
The C ₂ group represents an aromatic ring structure, and each C ₂ group forms a ring of 5 or 6 atoms with the adjacent imide group.
Structural unit (B):

(The C ₃ group represents an aromatic ring structure, and the C ₃ group forms a ring of 5 or 6 atoms together with the adjacent imide group.
Ar is a structural unit having an aromatic ring structure substituted with at least one sulfonic acid group.
X is hydrogen or a cationic species.
n represents an integer of 1 to 4)
(C _{1 to} C ₃ in the general formulas (1) to (3) may be the same or different) The resin composition according to claim 1, wherein the mixing ratio of the polyimide resin and the ionic liquid is ionic liquid/(total amount of ionic liquid and polyimide resin) of 50% by weight or more. The structural unit (A) is

The resin composition according to claim 1, which has a structure represented by: The structural unit (A) is

The resin composition according to claim 1 or 2, which has a structure represented by: The structural unit (B) is

The resin composition according to claim 1, which has a structure represented by: The structural unit (B) is

The resin composition according to claim 1, which has a structure represented by: The resin composition according to claim 1, 2, 3, 4, 5 or 6, wherein the constitutional unit A/(constitutional unit A+constitutional unit B) of the polyimide resin is 20 to 50% (mol conversion). A resin film comprising the resin composition according to claim 1, 2, 3, 4, 5, 6 or 7. A resin film containing a fluorine-containing polyimide resin and an ionic liquid,
A resin film having a tensile elastic modulus of 10 MPa or more and a breaking stress by a tensile test of 10 MPa or more. A gas permeable film comprising the resin film according to claim 8. The gas permeable membrane according to claim 10, which is a carbon dioxide selective permeable membrane.

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