JP3690415B1 - Humidity sensor - Google Patents

Abstract

【選択図】図１ Provided is a humidity sensor having excellent heat resistance and water resistance, excellent ion exchange capacity and proton conductivity, improved dimensional change at the time of water absorption, and improved adhesion to a supporting substrate.
A humidity sensor 10 having a plurality of electrodes 14 and 15 formed on a support substrate 11 and a moisture sensitive film made of a polymer electrolyte covering the electrodes 14 and 15, wherein the moisture sensitive film has the following chemical formula: Branched cross-linked sulfonated polyimide having an acid-terminated sulfonated polyimide having a repeating unit represented by (1) and having both ends composed of aromatic tetracarboxylic acid component residues and branched with a trifunctional or higher functional aromatic amine compound. It consists of a film 18.
[Chemical 1]

[Selection] Figure 1

Description

  The present invention relates to a humidity sensor using a moisture sensitive film made of a polymer electrolyte as the moisture sensitive film of the humidity sensor, and more particularly, to use a moisture sensitive film of a polymer electrolyte capable of measuring humidity at high temperature and high humidity. It relates to a humidity sensor.

  Conventionally, an electrical resistance type humidity sensor is generated between the electrodes that change the moisture content of the moisture-sensitive element of the moisture-sensitive film that covers a plurality of electrodes formed on the support substrate and absorbs moisture in the air. The resistance value is measured. That is, the measurement is performed by the fact that when the humidity is high (the amount of moisture in the air) is high, electricity flows between the electrodes, and when the humidity is low (the amount of moisture in the air is low), it is difficult for electricity to flow between the electrodes. For the moisture sensitive element used for the moisture sensitive film of this humidity sensor, a polymer electrolyte made of an organic polymer, in particular, an ion conductive polymer having a polyacrylic or polyvinyl skeleton is used. However, when a humidity sensor made of an organic polymer is used for the humidity sensor, the moisture sensor has a problem that it is inferior in heat resistance and water resistance.

As a polymer electrolyte having excellent heat resistance and high hygroscopicity, a sulfonated polyimide having a sulfonic acid group has been proposed, for example, for a polymer electrolyte membrane for a fuel cell (for example, Patent Document 1 and Patent Document 2). , Patent Document 3 see). However, these sulfonated polyimides have an extremely poor water resistance because the imide bond is easily hydrolyzed due to the electron-withdrawing sulfonic acid group, and thus cannot be used for the moisture sensitive film of the humidity sensor. In order to have water resistance, a copolymerized polyimide containing a large amount of a non-sulfonic acid group-containing component was studied by reducing the sulfonic acid group-containing component that is easily hydrolyzed. Since the sulfonic acid group content is decreased, characteristics such as ion exchange capacity and proton conductivity are remarkably decreased, which is not preferable. For this reason, a sulfonated polyimide having excellent ion exchange capacity and proton conductivity and improved water resistance, dimensional change upon water absorption, and the like has been demanded.

As the sulfonated polyimide having improved water resistance, a sulfonated polyimide using a specific sulfonated diamine is disclosed (for example, see Patent Documents 4 and 5 ). However, these sulfonated polyimides have room for further improvement in terms of water resistance and dimensional changes upon water absorption.

In addition, the polyimide resin composition includes a repeating structural unit obtained by polycondensation of a polyfunctional component containing three or more amino groups and tetracarboxylic dianhydride, a diamine having a sulfonic acid group, and tetracarboxylic dianhydride. What consists of a repeating structural unit obtained by polycondensation with a product is disclosed (for example, see Patent Document 6 and Patent Document 7 ), and a method for producing such a polyimide copolymer is disclosed (for example, Patent Reference 8 ). However, the polyimide resin compositions and polyimide copolymers disclosed in these patent documents maintain the solubility in organic solvents so that gel is not generated during the production process and the processability such as film formation is not significantly reduced. It was obtained by controlling so as to sag and was substantially uncrosslinked. Moreover, these patent documents do not suggest at all about the improvement of the water resistance which a bridge | crosslinking sulfonated polyimide has, and the improvement of a water absorption dimension change.

In the conventional patent documents, there has been disclosed a sulfonated polyimide and a separation membrane made of the sulfonated polyimide (see, for example, Patent Document 9 , Patent Document 10 , Patent Document 11 , Patent Document 12 , and Patent Document 13) . ). However, these patent documents do not mention cross-linked sulfonated polyimide.
In addition, in the conventional patent documents, there is one that refers to a polyimide product formed by a dehydration / ring-closing reaction of a three-dimensional network structure of polyamic acid mainly composed of a polyvalent amine (for example, Patent Document 14). reference). However, this patent document makes no mention of sulfonated polyimide.
JP 2000-510511 A JP 2002-358978 A JP 2002-367627 A Special table 2003-511500 gazette JP 2003-64181 A JP-A-11-281606 JP 2003-68326 A JP 2002-105199 A JP 2002-105200 A Japanese Patent Laid-Open No. 5-192552 JP-A-6-87957 JP-A-8-333451 JP-A-8-333453 JP-A-4-189865

  In the present invention, the moisture-sensitive membrane used in the humidity sensor is composed of a polymer electrolyte membrane made of a sulfonated polyimide excellent in heat resistance and water resistance as a moisture-sensitive element, and has excellent ion exchange capacity, proton conductivity, and water absorption. It is an object of the present invention to provide a humidity sensor with improved dimensional change and the like, and also improved adhesion to a support substrate made of ceramic.

［ここで、Ａｒ^１及びＡｒ^４は芳香環を有する４価の基であり、Ａｒ^２は１つ以上のスルホン酸基又はスルホン酸基の誘導体を置換基とする芳香環を有する２価の基であり、Ａｒ^５はスルホン酸基又はスルホン酸基の誘導体を置換基としない芳香環を有する２価の基であり、ｌは１以上の整数であり、ｍは０又は１以上の整数である。] A humidity sensor according to the present invention that meets the above-mentioned object is a humidity sensor having a plurality of electrodes formed on a support substrate and a moisture-sensitive film made of a polymer electrolyte that covers the electrodes, wherein the moisture-sensitive film has the following chemical formula: Branched cross-linked sulfonated polyimide having an acid-terminated sulfonated polyimide having a repeating unit represented by (1) and having both ends composed of aromatic tetracarboxylic acid component residues and branched with a trifunctional or higher functional aromatic amine compound. It consists of a membrane.

[Wherein Ar ¹ and Ar ⁴ are tetravalent groups having an aromatic ring, and Ar ² is a divalent group having an aromatic ring substituted with one or more sulfonic acid groups or derivatives of sulfonic acid groups. Ar ⁵ is a divalent group having an aromatic ring that does not use a sulfonic acid group or a derivative of a sulfonic acid group as a substituent, l is an integer of 1 or more, and m is 0 or an integer of 1 or more. . ]

Here, the humidity sensor is preferably made of a branched and cross-linked sulfonated polyimide in which Ar ¹ and / or Ar ⁴ in the chemical formula (1) is a tetravalent group represented by the following chemical formula (2).

［ここで、Ｄ^１は、Ｏ、ＣＨ_２、Ｃ（ＣＨ_３）_２、Ｃ（ＣＦ_３）_２、Ｏ＝Ｓ＝Ｏ又はＣ＝Ｏを示し、Ｒ^１〜Ｒ^３は、それぞれ独立に水素原子又は炭素数１〜２のアルキル基を示し、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンを示す。] Further, the humidity sensor is preferably made of a branched and crosslinked sulfonated polyimide in which Ar ^{2 in the} chemical formula (1) is a divalent group represented by the following chemical formula (3).

[Wherein D ¹ represents O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O = S═O or C═O, and R ^{1 to} R ³ each independently represent hydrogen An atom or a C1-C2 alkyl group is shown, and X shows a hydrogen atom, an alkali metal, ammonium, or a quaternary amine. ]

［ここで、Ｄ^２は、Ｏ又はＣ（ＣＨ_３）_２を示し、Ｒ^４〜Ｒ^７は、それぞれ独立に水素原子又は炭素数１〜２のアルキル基を示し、下記の化１１に示すように、Ａｒ^３は、

（式中、Ｄ^３は、直接結合、Ｏ、ＣＨ_２、Ｃ（ＣＨ_３）_２、Ｃ（ＣＦ_３）_２、Ｏ＝Ｓ＝Ｏ又はＣ＝Ｏを示し、Ｒ^８〜Ｒ^１０は、それぞれ独立に水素原子又は炭素数１〜２のアルキル基を示し、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンを示し、ｎは、０、１又は２の整数を示す。）である。] The humidity sensor may be made of a branched and crosslinked sulfonated polyimide in which Ar ^{2 in the} chemical formula (1) is a divalent group represented by the following chemical formula (4).

[Wherein D ² represents O or C (CH ₃ ) ₂ , and R ^{4 to} R ⁷ each independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, as shown in Chemical Formula 11 below. And Ar ³ is

(In the formula, D ³ represents a direct bond, O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O = S═O or C═O, and R ^{8 to} R ¹⁰ each represents Independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, X represents a hydrogen atom, an alkali metal, ammonium or a quaternary amine, and n represents an integer of 0, 1 or 2. ]

［ここで、Ｒ^１１〜Ｒ^１３は、それぞれ独立に、水素原子又は炭素数１〜２のアルキル基を表し、ｐは、１又は２の整数であり、ｎは、１〜６の整数であり、ｋは、１又は２の整数であり（ただし、ｋが２のとき、Ｒ^１３は、存在しない）、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンである。] Further, the humidity sensor is preferably made of a branched cross-linked sulfonated polyimide in which Ar ^{2 in the} chemical formula (1) is a divalent group represented by the following chemical formula (5).

[Wherein R ^{11 to} R ¹³ each independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, p is an integer of 1 or 2, and n is an integer of 1 to 6. , K is an integer of 1 or 2 (provided that when k is 2, R ¹³ is not present), and X is a hydrogen atom, an alkali metal, ammonium or a quaternary amine. ]

  The humidity sensor according to the present invention that meets the above-described object is (1) an aromatic diamine component Mb mole and an aromatic tetracarboxylic acid component Ma mole in an organic solvent, with a molar ratio Ma / Mb of 1.03 to 1.5. The organic solvent-soluble acid-terminal sulfonated polyimide whose terminal group is composed of an aromatic tetracarboxylic acid component residue is synthesized by reacting in the range of (2), and (2) the acid-terminal sulfonated polyimide solution at a temperature of 100 ° C. or less. A trifunctional or higher functional aromatic amine is added, mixed and reacted so that the aromatic tetracarboxylic acid component residue and amino group at both ends are approximately equimolar, and a branched sulfonated polyamic acid solution having a high degree of polymerization is obtained. (3) A moisture-sensitive film made of a branched cross-linked sulfonated polyimide formed by heating the solution at a temperature of 110 ° C. to 300 ° C. to perform solvent removal and thermal imidization is used. .

  6. The humidity sensor according to claim 1 and any one of claims 2 to 5 dependent thereon, and a humidity sensor according to claim 6, wherein the moisture sensitive element of a polymer electrolyte made of a branched and crosslinked sulfonated polyimide is used as a moisture sensitive film. Since it is provided, the moisture sensitive film has high heat resistance and water resistance. In addition, even if the degree of branching cross-linking is increased, the decrease in conductivity is small and the proton conductivity is excellent. Furthermore, while maintaining the conductivity, the dimensional change at the time of water absorption is improved, and the adhesion to the support substrate made of ceramic is also improved. Therefore, the humidity sensor using the moisture-sensitive film of the present invention can exhibit performance even in an environment of high temperature, high humidity, and condensed atmosphere, and can be applied as various high temperature and high humidity control sensors.

Subsequently, the best mode when the present invention is embodied will be described with reference to the accompanying drawings to provide an understanding of the present invention.
Here, FIG. 1 is an explanatory view of a humidity sensor according to an embodiment of the present invention, FIG. 2 is a graph showing the results of a water resistance test of Example 1 of the humidity sensor, and FIG. FIG. 4 is a graph showing the result of the water resistance test of Example 3, FIG. 4 is a graph showing the result of the water resistance test of Comparative Example 1, and FIG. 5 is an example of the humidity sensor according to one embodiment of the present invention. FIG. 6 is a graph showing the results of performing the high-temperature and high-humidity test of Example 3 of the humidity sensor.

  As shown in FIG. 1, a humidity sensor 10 according to an embodiment of the present invention is a resistance change type humidity sensor, and is formed of an Au vapor deposition film or the like on a support substrate 11 made of a ceramic substrate or a resin substrate. The first comb electrode 12 and the second comb electrode 13 are provided. The first comb-like electrode 12 has one or more first electrode portions 14, the second comb-like electrode 13 has one or more second electrode portions 15, and the first The electrode portions 14 and the second electrode portions 15 are alternately formed in parallel. Pin electrodes 16 for electrical connection to the outside sandwich the ends of the support substrate 11 at the tips of the base portions of the first comb electrode 12 and the second comb electrode 13, respectively. Thus, one end is connected with solder or the like. Furthermore, in order to protect the connection part, an insulator 17 made of insulating resin, glass or the like is formed on the connection part so as to cover the whole connection part. Then, on the support substrate 11, the first comb electrode 12 including the first electrode portion 14 and the second comb electrode 13 including the second electrode portion 15 are sandwiched and covered so as to be sensitive. A branched and crosslinked sulfonated polyimide film 18 represented by the chemical formula (1), which is a wet film, is formed.

  Here, the branched cross-linked sulfonated polyimide represented by the chemical formula (1) for forming the moisture-sensitive film of the present invention has an aromatic tetracarboxylic acid component and a sulfonic acid group or a derivative group thereof as a substituent. It is synthesized from an aromatic diamine component containing a sulfonated aromatic diamine and a trifunctional or higher functional aromatic amine compound. In addition, the sulfonic acid group or derivative group in this case is a sulfonic acid group, an alkoxysulfonic acid group, and a salt thereof with an alkali metal such as sodium, potassium, lithium, tributylamine, triethylamine, trimethylamine, N, N-dimethyl. A salt with a tertiary amine such as aniline or a cyclic amine such as pyridine.

In addition, the aromatic tetracarboxylic acid component used for the synthesis of the branched cross-linked sulfonated polyimide for forming the moisture-sensitive film of the present invention is not particularly limited, but for example, 3, 3 ′, 4 , 4'-biphenyltetracarboxylic acid, 2,3 ', 3,4'-biphenyltetracarboxylic acid, 3,3', 4,4'-base emission zone phenone tetracarboxylic acid, 3,3 ', 4,4 '-Diphenyl ether tetracarboxylic acid, bis (3,4-dicarboxyphenyl) methane, 2,2-bis (3,4-dicarboxyphenyl) propane, pyromellitic acid, 1,4,5,8-naphthalenetetracarboxylic Acid, 3,4,9,10-perylenetetracarboxylic acid, 4,4 ′-(hexafluoroisopropylidene) diphthalic acid, m- (terphenyl) 3,4,3 ″, 4 ″ -tetracarboxylic acid, It may be mentioned those acid dianhydride or ester. Among these, 1,4,5,8-naphthalenetetracarboxylic acid, or its acid dianhydride or esterified product is particularly preferable because a branched and crosslinked sulfonated polyimide having good water resistance can be easily obtained.

  Furthermore, as the sulfonated aromatic diamine having a sulfonic acid group or a derivative group thereof as a substituent contained in the aromatic diamine component used for the synthesis of the branched cross-linked sulfonated polyimide for forming the moisture sensitive film of the present invention, Benzidine 2,2′-disulfonic acid, 1,4-diaminobenzene-3-sulfonic acid, 1,3-diaminobenzene-4-sulfonic acid, 4,4′-diamino-5,5′-dimethyl- (1, 1'-biphenyl) -2,2'-disulfonic acid, and those whose sulfonic acids are sulfonic acid derivatives, and sulfonated aromatic diamines represented by the following chemical formula (6), Examples thereof include sulfonated aromatic diamines represented by the formula and alkoxysulfonated aromatic diamines represented by the following chemical formula (8).

［ここで、Ｄ^１は、Ｏ、ＣＨ_２、Ｃ（ＣＨ_３）_２、Ｃ（ＣＦ_３）_２、Ｏ＝Ｓ＝Ｏ又はＣ＝Ｏを示し、Ｒ^１〜Ｒ^３は、それぞれ独立に水素原子又は炭素数１〜２のアルキル基を示し、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンを示す。］

[Wherein D ¹ represents O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O = S═O or C═O, and R ^{1 to} R ³ each independently represent hydrogen An atom or a C1-C2 alkyl group is shown, and X shows a hydrogen atom, an alkali metal, ammonium, or a quaternary amine. ]

［ここで、Ｄ^２は、Ｏ又はＣ（ＣＨ_３）_２を示し、Ｒ^４〜Ｒ^７は、それぞれ独立に水素原子又は炭素数１〜２のアルキル基を示し、下記の化１５に示すように、Ａｒ^３は、

[Wherein D ² represents O or C (CH ₃ ) ₂ , and R ^{4 to} R ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, as shown in Chemical Formula 15 below. And Ar ³ is

あるいは、下記の化１６に示すように、Ａｒ^３は、

Alternatively, as shown in Chemical Formula 16 below, Ar ³ is

（式中、Ｄ^３は、直接結合、Ｏ、ＣＨ_２、Ｃ（ＣＨ_３）_２、Ｃ（ＣＦ_３）_２、Ｏ＝Ｓ＝Ｏ又はＣ＝Ｏを示し、Ｒ^８〜Ｒ^１０は、それぞれ独立に水素原子又は炭素数１〜２のアルキル基を示し、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンを示し、ｎは、０、１又は２の整数を示す。）である。]

(In the formula, D ³ represents a direct bond, O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O = S═O or C═O, and R ^{8 to} R ¹⁰ each represents Independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, X represents a hydrogen atom, an alkali metal, ammonium or a quaternary amine, and n represents an integer of 0, 1 or 2. ]

［ここで、Ｒ^１１〜Ｒ^１３は、それぞれ独立に、水素原子又は炭素数１〜２のアルキル基を表し、ｐは、１又は２の整数であり、ｎは、１〜６の整数であり、ｋは、１又は２の整数であり（ただし、ｋが２のとき、Ｒ^１３は、存在しない）、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンである。]

[Wherein R ^{11 to} R ¹³ each independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, p is an integer of 1 or 2, and n is an integer of 1 to 6. , K is an integer of 1 or 2 (provided that when k is 2, R ¹³ is not present), and X is a hydrogen atom, an alkali metal, ammonium or a quaternary amine. ]

  Among the sulfonated aromatic diamines having a sulfonic acid group or a derivative group as the substituent, a branched and crosslinked sulfonated polyimide having good water resistance can be obtained. Therefore, the above chemical formula (6) to chemical formula The sulfonated aromatic diamine represented by (8), particularly the sulfonated aromatic diamine represented by chemical formula (7) and chemical formula (8) is preferred.

The sulfonated aromatic diamines represented by the chemical formula (6), the chemical formula (7), and the chemical formula (8) have different synthesis methods depending on their structures. Although not particularly limited, for example, it can be suitably synthesized by the following method.
The sulfonated aromatic diamine represented by the chemical formula (6) is converted to a sulfate by the method described in Hosoda, “Theoretical Manufacturing Dye Chemistry”, Gihosha, Tokyo, 1957, etc. Can be synthesized. At this time, the aromatic diamine used is one in which the aromatic ring is bonded with O, CH ₂ , C (CF ₃ ) ₂ , SO ₂ , and CO interposed therebetween. Specifically, 3, 4′- Oxydianiline, 4,4'-oxydianiline, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diamino Diphenylmethane, 3,3′-diethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetraethyl- 4,4′-diaminodiphenylmethane, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4-aminophenyl) Propane, 2,2-bis (4-aminophenyl) hexafluoropropane, bis (4-aminophenyl) sulfone, bis (3-aminophenyl) sulfone, can be given 3,3'-benzophenone.

As shown in the chemical formula 18 below, Ar ³ in the above chemical formula (7) is

（式中、Ｄ^３は、直接結合、Ｏ、ＣＨ_２、Ｃ（ＣＨ_３）_２、Ｃ（ＣＦ_３）_２、を示し、Ｒ^８〜Ｒ^１０は、それぞれ独立に水素原子又は炭素数１〜２のアルキル基を示し、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンを示し、ｎは、０〜２の整数を示す。）の構造、すなわち、アミノ基に結合していない芳香環が電子吸引基と結合していないスルホン酸基含有芳香族ジアミンの場合、例えば、（Ａ）芳香族ジアミンを濃硫酸中で、細田、「理論製造 染料化学」、技報社発行、東京、１９５７年等に記載の方法でスルホン化する方法、（Ｂ）二価フェノールを濃硫酸中で、細田、「理論製造 染料化学」、技報社発行、東京、１９５７年等に記載の方法でスルホン化後、特開平９−２４１２２５号公報等に記載の方法でニトロ基を有する芳香族ハライドと反応させ、ジニトロ化合物を合成し、その後、ニトロ基を還元することによってジアミン化合物とする方法、等によって合成することができる。

(Wherein D ³ represents a direct bond, O, CH ₂ , C (CH ₃ ) ₂ , or C (CF ₃ ) ₂ , and R ^{8 to} R ¹⁰ each independently represent a hydrogen atom or a carbon number of 1 to 2 represents an alkyl group, X represents a hydrogen atom, an alkali metal, ammonium or a quaternary amine, and n represents an integer of 0 to 2.), that is, an aromatic ring not bonded to an amino group Is a sulfonic acid group-containing aromatic diamine that is not bonded to an electron withdrawing group, for example, (A) Aromatic diamine in concentrated sulfuric acid, Hosoda, “Theoretical Manufacturing Dye Chemistry”, published by Gihosha, Tokyo, 1957 A method of sulfonation by the method described in the above, (B) after sulfonation by the method described in Hosoda, “Theoretical Production Dye Chemistry”, Gihosha, Tokyo, 1957 etc. in concentrated sulfuric acid, In the method described in JP-A-9-241225 It can be synthesized by reacting with an aromatic halide having a nitro group to synthesize a dinitro compound and then reducing the nitro group to obtain a diamine compound.

The aromatic diamine used as a raw material in the reaction (A) is one in which an aromatic ring not bonded to an amino group is not bonded to an electron-withdrawing group. For example, 1,3-bis (4- Aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, Examples include 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, α, α′-bis (4-aminophenyl) -1,4-diisopropylbenzene, and the like.
Examples of the dihydric phenol that can be used as a raw material in the reaction (B) are those in which an aromatic ring is not bonded to an electron-withdrawing group, such as hydroquinone, resorcinol, 4,4′-biphenol, 2,2′-biphenol, bis (4-hydroxyphenyl) ether, bis (2-hydroxyphenyl) ether, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3-methyl-4-) Hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 1, 3-bis (4-hydroxyphenoxy) benzene, 1,4-bis (3-hydroxyphenoxy) benzene And the like can be given. As aromatic halides having a nitro group, 2-chloronitrobenzene, 3-chloronitrobenzene, 4-chloronitrobenzene, 2-fluoronitrobenzene, 3-fluoronitrobenzene, 4-fluoronitrobenzene, bis (2-hydroxy-5-methylphenyl) ) Methane and the like.

As shown in the chemical formula 19 below, Ar ^{3 in} the chemical formula (7) is

（式中、Ｄ^３は、Ｏ＝Ｓ＝Ｏ又はＣ＝Ｏを示し、Ｒ^８〜Ｒ^１０は、それぞれ独立に水素原子又は炭素数１〜２のアルキル基を示し、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンを示し、ｎは、１の整数を示す。）の構造で示される、すなわち、アミン基の結合していない芳香環が電子吸引基と結合している芳香族ジアミンの場合、例えば、（Ｃ）二価フェノールを発煙硫酸中で、細田、「理論製造 染料化学」、技報社発行、東京、１９５７年等に記載の方法でスルホン化後、特開平９−２４１２２５号公報等に記載の方法で、ニトロ基を有する芳香族ハライドと反応させ、ジニトロ化合物を合成し、その後、ニトロ基を還元することによってジアミン化合物とする方法等によって合成することができる。

(Wherein D ³ represents O═S═O or C═O, R ^{8 to} R ¹⁰ each independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and X represents a hydrogen atom, An aromatic diamine in which an aromatic ring to which an amine group is not bonded is bonded to an electron-withdrawing group, i.e., an alkali metal, ammonium or a quaternary amine, and n is an integer of 1. In the case of, for example, (C) divalent phenol in fuming sulfuric acid, and after sulfonation by the method described in Hosoda, “Theoretical Manufacturing Dye Chemistry”, published by Gihosha, Tokyo, 1957, etc., JP-A-9-241225 It can be synthesized by a method described in a publication or the like by reacting with an aromatic halide having a nitro group to synthesize a dinitro compound and then reducing the nitro group to obtain a diamine compound.

  As the dihydric phenol that can be used as a raw material in the reaction (C), an aromatic ring is bonded to an electron withdrawing group. For example, bis (4-hydroxyphenyl) sulfone, bis ( 4-hydroxyphenyl) ketone and the like, and examples of the aromatic halide having a nitro group include those described above.

As shown in the chemical formula 20 below, Ar ^{3 in} the chemical formula (7) is

［ここで、Ｘは、水素原子、アルカリ金属、アンモニウム又は４級アミンを表す。]の構造を有するスルホン酸基含有芳香族ジアミンの場合、例えば、（Ｄ）原料ジアミンを濃硫酸中で硫酸塩とし、その後、細田、「理論製造 染料化学」、技報社発行、東京、１９５７年等に記載の方法で発煙硫酸を用いてスルホン化することにより合成することができる。この時、用いられる原料ジアミンとして、９，９−ビス（４−アミノフェニル）フルオレンを挙げることができる。

[Wherein X represents a hydrogen atom, an alkali metal, ammonium or a quaternary amine. In the case of a sulfonic acid group-containing aromatic diamine having a structure of, for example, (D) Raw material diamine is converted into sulfate in concentrated sulfuric acid, then Hosoda, “Theoretical Manufacturing Dye Chemistry”, published by Gihosha, Tokyo, 1957 Etc. can be synthesized by sulfonation using fuming sulfuric acid by the method described in the above. At this time, 9, 9-bis (4-aminophenyl) fluorene can be mentioned as raw material diamine used.

  The sulfonated aromatic diamine having a ω-sulfoalkoxy group having the structure represented by the above chemical formula (8) is obtained by, for example, reacting an aromatic dinitro compound having a hydroxyl group with an alkali metal halide alkyl sulfonate. And synthesizing an aromatic dinitro compound having an ω-sulfoalkoxy group, and then reducing the nitro group to obtain an ω-sulfoalkoxy group-containing aromatic diamine, (F) an aromatic mononitro compound having a hydroxyl group and an alkyl halide By reacting with an alkali metal sulfonate, an aromatic mononitro compound having an ω-sulfoalkoxy group is synthesized, followed by an azo coupling reaction, followed by a reduction and rearrangement reaction, thereby obtaining an ω-sulfoalkoxy group-containing aromatic diamine. It can be prepared by a synthesis method according to the structure such as a method for obtaining

In the synthesis method (E) of the ω-sulfoalkoxy group-containing aromatic diamine, the reaction between the aromatic dinitro compound having a hydroxyl group and the alkali metal halide alkyl halide is an alkali metal of an aromatic dinitro compound having a hydroxyl group. It can be synthesized by reacting a salt with an alkali metal halide alkyl sulfonate in a polar solvent such as N, N-dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like at 50 to 140 ° C. for 1 to 80 hours.
The aromatic mononitro compound having a hydroxyl group has at least one aromatic ring and has two nitro groups directly bonded to the aromatic ring and at least one hydroxyl group. , 4-dinitrophenol, 2,5-dinitrophenol, 4,6-dinitrocresol, 3,5-dinitrocatechol, 4,4′-dihydroxy- (3,3′-dinitro) biphenyl, etc. it can.
The alkali metal salt of the aromatic dinitro compound having a hydroxyl group includes, in the polar solvent, an aromatic dinitro compound having a hydroxyl group and potassium carbonate, sodium carbonate or the like, and toluene, benzene, xylene or the like as an azeotropic solvent. It can synthesize | combine by reacting at 100-160 degreeC for 0.5 to 5 hours, removing the water | moisture content to produce | generate.
The alkali metal sulfonic acid alkali metal salt is a halogenated alkyl compound having a sulfonic acid alkali metal salt at the terminal, such as 2-bromoethanesulfonic acid, 3-bromopropanesulfonic acid, 4-bromobutane. Preferable examples include potassium, sodium and lithium salts such as sulfonic acid.

  In the synthesis method (E) of the ω-sulfoalkoxy group-containing aromatic diamine, the reduction of the nitro group of the aromatic dinitro compound having the ω-sulfoalkoxy group is performed by the Chemical Society of Japan, New Experimental Chemistry Course 15, Known methods such as those described in Reduction, Maruzen, 1975 and the like can be used, and for example, this is achieved by hydrogenation using Pd / C.

  The aromatic mononitro compound having a hydroxyl group used in the synthesis method (F) of the ω-sulfoalkoxy group-containing aromatic diamine is an aromatic mononitro compound having at least one hydroxyl group, such as m-nitrophenol. O-nitrophenol and the like can be preferably mentioned.

In the synthesis method (F) of the ω-sulfoalkoxy group-containing aromatic diamine, the aromatic mononitro compound having a ω-sulfoalkoxy acid group includes an aromatic mononitro compound having a hydroxyl group, and an alkali metal halide alkyl sulfonate. Can be synthesized in the same manner as described in the synthesis method (E) of the ω-sulfoalkoxy group-containing aromatic diamine.
In this synthesis method (F), the azo coupling reaction and the subsequent rearrangement reaction can be carried out using known methods as described in the Chemical Society of Japan, New Experimental Chemistry Course 15, Oxidation and Reduction, Maruzen, 1975, etc. For example, Zn / NaOH / methanol is heated in water to azobenzene, then Zn / ethanol is heated in ammonia to hydrazobenzene, and heated in concentrated hydrochloric acid to achieve benzidine transition. The

  The ω-sulfoalkoxy group-containing aromatic diamine having the structure represented by the chemical formula (8) used for the synthesis of the branched and cross-linked sulfonated polyimide for forming the moisture sensitive film of the humidity sensor of the present invention is particularly limited. Specifically, 2- (2,4-diaminophenoxy) ethanesulfonic acid, 3- (2,4-diaminophenoxy) propanesulfonic acid, 4- (2,4-diaminophenoxy) Butanesulfonic acid, 2- (2,5-diaminophenoxy) ethanesulfonic acid, 3- (2,5-diaminophenoxy) propanesulfonic acid, 4- (2,5-diaminophenoxy) butanesulfonic acid, 2- (4 , 6-Diamino-2-methylphenoxy) ethanesulfonic acid, 3- (4,6-diamino-2-methylphenoxy) propanesulfonic acid 4- (4,6-diamino-2-methylphenoxy) butanesulfonic acid, 1,5-diamino-2,3-di (2-sulfoethoxy) benzene, 1,5-diamino-2,3-di (3 -Sulfopropoxy) benzene, 1,5-diamino-2,3-di (4-sulfobutoxy) benzene, 2,2'-bis (3-sulfopropoxy) benzidine, 3,3'-bis (3-sulfopropoxy) ) Benzidine and the like can be preferably mentioned. Particularly, since the ion exchange capacity can be increased, an ω-sulfoalkoxy group-containing aromatic diamine having two or more ω-sulfoalkoxy groups, for example, 1,5-diamino-2 , 3-Di (2-sulfoethoxy) benzene, 1,5-diamino-2,3-di (3-sulfopropoxy) benzene, 1,5-diamino-2,3-di (4-sulfobu) Alkoxy) benzene, 2,2'-bis (3-sulfopropoxy) benzidine, 3,3'-bis (3-sulfopropoxy) benzidine, and the like can be suitably cited.

In the synthesis of a branched cross-linked sulfonated polyimide for forming a moisture sensitive film of the humidity sensor of the present invention, a substituent group together with a sulfonated aromatic diamine having a sulfonic acid group or a derivative group as a substituent as an aromatic diamine component A non-sulfonated aromatic diamine having no sulfonic acid group or derivative group thereof can be used in combination. Examples of such non-sulfonated aromatic diamines include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, benzidine, metaphenylenediamine, paraphenylenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, bis [4- ( 4-aminophenoxy) phenyl] sulfone, bis- (4-aminophenoxyphenyl) sulfide, bis- (4-aminophenoxyphenyl) biphenyl, 1,4-bis- (4-aminophenoxy) benzene, 1,3-bis- (4-aminophenoxy) benzene, 3,4′-diaminodiphenyl ether, 4,4′-bis (4-aminophenoxy) biphenyl, Bis [4- (3-aminophenoxy) phenyl] s Hong, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (4-amonophenoxy) Phenyl] propane, 2,2′-bis (trifluoromethyl) -benzidine and the like.

  In the synthesis of the branched cross-linked sulfonated polyimide for forming the moisture sensitive film of the humidity sensor of the present invention, when a sulfonated aromatic diamine and a non-sulfonated aromatic diamine are used in combination as the aromatic diamine component, The ratio of the sulfonated aromatic diamine to the non-sulfonated aromatic diamine is such that the ion-exchange capacity of the resulting branched crosslinked sulfonated polyimide is 0.5 to 3.5 milliequivalent / g, particularly 1.5 to 3. It is preferably used at a rate such that it is in the range of 5 milliequivalents / g. In particular, the ratio of the sulfonated aromatic diamine is 60 mol% or more, preferably 65 mol% or more, and particularly 70 mol% or more in 100 mol% of the total aromatic diamine component, so that the ion exchange capacity is increased. This is preferable. If the ratio of non-sulfonated aromatic diamine exceeds 40 mol%, the ion exchange capacity is lowered, which is not preferable.

  In the synthesis of the branched cross-linked sulfonated polyimide for forming the moisture-sensitive film of the humidity sensor of the present invention, the aromatic tetracarboxylic acid component and the aromatic diamine component are Ma, When the number of moles of the aromatic diamine component is Mb, Ma / Mb is in the range of 1.03 to 1.5, preferably 1.04 to 1.33, and more preferably 1.05 to 1.33. Is used. When Ma / Mb is smaller than 1.03, the finally obtained branched cross-linked sulfonated polyimide is not sufficiently cross-linked. On the other hand, if it is larger than 1.5, the ion-exchange capacity of the finally obtained branched cross-linked sulfonated polyimide becomes small or becomes too hard.

  The trifunctional or higher functional aromatic amine compound used in the preparation of the branched cross-linked sulfonated polyimide for forming the moisture-sensitive film of the humidity sensor of the present invention includes the same aromatic ring to facilitate the cross-linking reaction. Preferred are those in which two amine groups are not adjacently bonded, particularly those in which two or more primary amine groups are not bonded to the same aromatic ring, such as 1,3,5-tri (4-amino Phenoxy) benzene, tri (4-aminophenyl) methane, 1,3,5-triaminobenzene, 5,10,15,20-tetrakis (4-aminophenyl) -21H, 23H-porphyrin and the like. From the viewpoint of heat resistance, 1,3,5-tri (4-aminophenoxy) benzene is particularly preferable.

The trifunctional or higher functional aromatic amine compound is used so as to be approximately equimolar with respect to the terminal group of the acid-terminal sulfonated polyimide. Specifically, when the number of moles of acid end groups of the acid-terminated sulfonated polyimide and M _2, the number of moles of amine groups of trifunctional or more aromatic amine compounds was M _3, molar ratio M _{3 /} M ₂ Is in the range of 0.9 to 1.1, preferably in the range of 0.92 to 1.08, and more preferably in the range of 0.95 to 1.05. When the molar ratio is smaller than 0.9 or larger than 1.1, the crosslinking is not sufficiently advanced, so that the finally obtained branched crosslinked sulfonated polyimide has a dimensional change upon water absorption, water resistance, etc. It may not be possible to improve sufficiently.

The branched cross-linked sulfonated polyimide for forming the moisture-sensitive film of the humidity sensor of the present invention is (1) an aromatic containing a sulfonated aromatic diamine having a sulfonic acid group or a derivative group as a substituent in an organic solvent. By reacting the diamine component Mb mole with the aromatic tetracarboxylic acid component Ma mole at a molar ratio Ma / Mb in the range of 1.03 to 1.5, the end group is substantially aromatic tetracarboxylic acid. An organic solvent-soluble acid-terminated sulfonated polyimide represented by the chemical formula (1) consisting of component residues is synthesized, and (2) an aromatic tetracarboxylic acid component in the acid-terminated sulfonated polyimide solution at a temperature of 100 ° C. or lower. A trifunctional or higher functional aromatic amine compound is added, mixed and reacted so that the residue terminal and the amino group are approximately equimolar, and a highly soluble branched sulfonated polyamic acid solution is obtained. The resulting, (3) the solution is heated at a temperature of 110 ° C. to 300 ° C., and is suitably prepared by performing solvent removal and thermal imidization.
In addition, the terminal of the acid terminal sulfonated polyimide whose terminal group is an aromatic tetracarboxylic acid component residue is specifically a dicarboxylic acid group, an esterified dicarboxylic acid group, or a dicarboxylic anhydride group.

  In the production of the branched cross-linked sulfonated polyimide for forming the moisture sensitive film of the humidity sensor of the present invention, a known method can be used for the synthesis of the acid-terminal sulfonated polyimide. Specifically, for example, in the polar organic solvent, the aromatic diamine component and the aromatic tetracarboxylic acid component in the above molar ratio, if necessary, in order to further promote the polymerization reaction or imide reaction, It can be easily achieved by adding toluene, xylene or the like as a tertiary amine or cyclic amine or an azeotropic solvent, and heating to 140 to 220 ° C. to react for 0.5 to 100 hours while removing the generated water. Further, benzoic acid or the like may be added as a catalyst. The tertiary amine or cyclic amine is preferably added in an equimolar amount or more with respect to the sulfonic acid group. The obtained acid-terminated sulfonated polyimide solution may be used as it is in the next step, or may be poured into a poor solvent, once the acid-terminated sulfonated polyimide is precipitated, and then dissolved again in a polar solvent. Good. Specific examples of the polar organic solvent used at this time include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, and N, N-dimethyl. Acetamide solvents such as acetamide and N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, O-cresol, m-cresol, p-cresol, m -Halogenated phenols such as cresolic acid, xylenol, p-chlorophenol, phenol solvents such as catechol, hexamethylphosphoramide, γ-butyrolactone, and the like. These organic solvents may be used alone or in combination of two or more.

When a sulfonated aromatic diamine and a non-sulfonated aromatic diamine are used as the aromatic diamine component, either a random copolymer or a block copolymer may be used.
When the acid-terminated sulfonated polyimide is a block copolymer comprising a sulfonated aromatic diamine component and a non-sulfonated aromatic diamine component, a predetermined amount is obtained in the same manner as in the above-described method for synthesizing an acid-terminated sulfonated polyimide. After synthesizing acid-terminated sulfonated polyimide (or non-sulfonated acid-terminated polyimide) using a sulfonated aromatic diamine (or non-sulfonated aromatic diamine) and a tetracarboxylic acid component, a predetermined amount of non-sulfone is added to the solution. It can be obtained by adding a sulfonated aromatic diamine (or sulfonated aromatic diamine) and a tetracarboxylic acid component and reacting them again under the conditions described above.

  In preparation of a branched cross-linked sulfonated polyimide for forming a moisture sensitive film of the humidity sensor of the present invention, following the preparation of an acid-terminated sulfonated polyimide solution, a trifunctional or higher functional aromatic amine compound is added to the solution and mixed. A prepared mixed solution is prepared. This mixed solution is prepared by adding and mixing an aromatic amine compound having three or more functions with the acid-terminated sulfonated polyimide solution at a temperature of 100 ° C. or lower, preferably 90 ° C. or lower, more preferably 80 ° C. or lower. Is done. If the temperature of the solution to be added and mixed is higher than 100 ° C., gelation may occur, which is not preferable. The mixed solution of the acid-terminated sulfonated polyimide thus obtained and the trifunctional or higher functional aromatic amine compound has a total solid component concentration of, for example, a high concentration of 5% by weight or more without gelation. can do. Here, the concentration of the mixed solution of the acid-terminated sulfonated polyimide and the trifunctional or higher functional aromatic amine compound is preferably 1 to 15% by weight, particularly 3 to 8% by weight, based on the total solid content. A solution having a low concentration is not preferable because the coating film becomes too thin when a branched cross-linked sulfonated polyimide moisture-sensitive film is produced. Moreover, when the solution concentration becomes too high, the film becomes too thick, which is not preferable.

  In preparation of the branched cross-linked sulfonated polyimide for forming the moisture sensitive film of the humidity sensor of the present invention, the mixed solution of the above-mentioned acid-terminal sulfonated polyimide and trifunctional or higher aromatic amine compound is heated to remove the solvent. A branched and crosslinked sulfonated polyimide is produced by advancing the crosslinking reaction. The final heating temperature at this time is a temperature of 110-300 degreeC, More preferably, it is the range of 150-250 degreeC. When the heating temperature is lower than 110 ° C., the imidization reaction and the crosslinking reaction do not proceed sufficiently, which is not preferable. On the other hand, when the temperature is higher than 300 ° C., a decomposition reaction such as a sulfonic acid group or a sulfonic acid derivative group is not preferable. The heating time is 1 minute to 48 hours, preferably 2 minutes to 24 hours. In this step, the solution is applied to a support such as a ceramic substrate on which comb-shaped electrodes are formed, heated, and the humidity sensitivity of a humidity sensor comprising a branched and crosslinked sulfonated polyimide that has undergone a crosslinking reaction along with solvent removal. A film can be easily obtained. At this time, if necessary, in order to facilitate the removal of the solvent, it may be immersed in methanol, ethanol, isopropanol, acetone or the like at 10 to 50 ° C. for 0.5 minute to 24 hours.

  When a tertiary amine or a cyclic amine is added in the above-described production process, or the sulfonated aromatic diamine used is a derivative of the above-described sulfonic acid group, it can be used as it is as a moisture-sensitive film of a humidity sensor. It can also be used in the proton type or other ionic salt type by ion exchange as described later.

  In the preparation of the branched and crosslinked sulfonated polyimide for forming the moisture sensitive film of the humidity sensor of the present invention, the substituent of the sulfonated aromatic diamine may be sulfonic acid or a derivative of sulfonic acid. When it is necessary to increase the solubility of, it is preferable to form a salt with a tertiary amine or a cyclic amine. The moisture-sensitive film produced by applying this polymerization solution is an amine salt type. By immersing this moisture-sensitive film in an aqueous solution of 0.01 to 1N sulfuric acid or the like at 10 to 80 ° C. for 0.5 minutes to 10 hours, the substituent can be acid-substituted with sulfonic acid. Further, a branched or crosslinked sulfonated polyimide moisture-sensitive membrane having an amine salt or a proton type substituent in an aqueous solution of an alkali metal halide of 0.1 to 3 molar concentration at 10 to 80 ° C. for 0.5 minutes to 2 By soaking for a time, it can be converted to a substituent of the corresponding derivative.

  The branched cross-linked sulfonated polyimide for forming the moisture sensitive film of the humidity sensor of the present invention is, for example, an organic solvent in which acid-terminated sulfonated polyimide can be dissolved, specifically, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide. N, N-dimethylformamide, N, N-diethylformamide and other formamide solvents, N, N-dimethylacetamide, N, N-diethylacetamide and other acetamide solvents, N-methyl-2-pyrrolidone, N-vinyl Pyrrolidone solvents such as 2-pyrrolidone, phenol, o-cresol, m-cresol, p-cresol, m-cresolic acid, xylenol, phenol solvents such as p-chlorophenol, phenol solvents such as catechol, or Hexamethylphosphoramide, γ-buty Lactones such as, in particular, m- cresol and N- methyl-2-pyrrolidone, is crosslinked to a substantially extent insoluble.

  The humidity-sensitive film of the polymer electrolyte of the humidity sensor of the present invention comprises the branched and crosslinked sulfonated polyimide. Preferably, the ion exchange capacity is as high as 0.5 to 3.5 milliequivalent / g, particularly 1.5 to 3.5 milliequivalent / g, and the dimensional stability during water absorption is preferred. And water resistance is improved. Further, the moisture sensitive film may be a composition containing a resin component other than the branched cross-linked sulfonated polyimide, but the branched cross-linked sulfonated polyimide is 10% by weight or more of the total resin component, preferably It is preferably 50% by weight or more, more preferably 80% by weight or more, and particularly preferably 100% by weight. If it is less than 10% by weight in the total resin components, it is difficult to develop the characteristics of the branched and crosslinked sulfonated polyimide as a good electrolyte. Furthermore, when comprising a composition with another resin component, another resin component is not specifically limited, For example, you may use the aromatic polyimide which has or does not have a sulfonic acid group as a substituent.

  In the humidity sensor of the present invention, the branched cross-linked sulfonated polyimide membrane, which is a moisture sensitive membrane of a polymer electrolyte, is improved so that the dimensional change with respect to water immersion is reduced, and the adhesiveness to the support substrate is strong. Because it is, it is extremely durable.

  Examples of the present invention and comparative examples will be described below. It should be noted that the polymer electrolyte moisture sensitive films shown in the examples and comparative examples have the first electrode part 14 and the first electrode part 14 so that the resistance between the two pin electrodes 16 and 16 in FIG. The number of the two electrode parts 15 and the distance between them are set.

[Synthesis Example 1]
Synthesis of 1,3,5-tri (4-aminophenoxy) benzene (hereinafter sometimes abbreviated as TAPB) 49.6 g (0.35 mol) of 4-fluoronitrobenzene, 1,3,5-trihydroxy 12.6 g (0.1 mol) of benzene and 20.7 g (0.15 mol) of K ₂ CO ₃ were added to 200 ml of dimethyl sulfoxide and 50 ml of toluene, and heated under a nitrogen stream. The produced water was removed while refluxing toluene at 140 ° C. for 4 hours. While removing toluene, the temperature was raised to 175 ° C. and heated for 16 hours. After cooling, it was precipitated in a large amount of methanol, and the obtained solid was washed with water three times and dried.
30 g of the obtained solid, 60 mg of iron (III) chloride, and 2 g of platinum-supported carbon were added to 110 ml of 2-methoxyethanol, and after heating to 90 ° C., 18.9 g of hydrazine hydrate was added dropwise over 2 hours. After heating at 110 ° C. for 2 hours, it was cooled to room temperature and filtered. 20 ml of concentrated hydrochloric acid was added to the filtrate to precipitate a solid. The obtained solid was separated by filtration, washed with acetone, dried, and dissolved in water. Aqueous ammonia was added to precipitate a solid. The solid was filtered off and dried to give a yellow solid. The obtained yellow solid was confirmed to be TAPB by H-NMR measurement.

[Example 1] (Acid anhydride 1,4,5,8-naphthalenetetracarboxylic acid (hereinafter sometimes abbreviated as NTDA) / diamine 2,2′-bis (3-sulfopropoxy) benzidine ( Hereinafter, it may be abbreviated as 2,2′-BSPB.) = 6/5)
(1) Synthesis of 3- (3′-nitrophenoxy) propanesulfonic acid Na In the procedure shown below, Na salt of 3- (3′-nitrophenoxy) propanesulfonic acid having the following chemical structural formula Synthesized.

To a completely dried 100 ml four-necked flask, 13.9 g (100 mmol) of m-nitrophenol and 120 ml of DMF were added and stirred in a nitrogen atmosphere. After m-nitrophenol was dissolved, 20 g (150 mmol) of K ₂ CO _{3 and} 20 ml of toluene were added. The reaction mixture was stirred for 30 minutes at room temperature, and then heated and refluxed for 2 hours. The reaction mixture was again cooled to room temperature and 22.5 g (100 mmol) of 3-promopropanesulfonic acid Na was added in one portion. The reaction mixture was reheated to 110 ° C. and held at this temperature for 24 hours. Next, after cooling to room temperature, the dark orange reaction solution was filtered, and the precipitate was washed with acetone. Next, it was vacuum-dried at 40 ° C. for 10 hours. 300 ml of DMSO was added to the obtained solid, the mixture was stirred for 30 minutes at room temperature, and insoluble inorganic salts were removed by filtration. Further, the solvent (DMSO) was distilled off from the filtrate under reduced pressure, and the resulting solid was washed with acetone and vacuum-dried at 50 ° C. for 20 hours. The product was purified by recrystallization from methanol to obtain 24 g of Na (3- (3′-nitrophenoxy) propanesulfonate having the chemical structural formula of Chemical Formula 21. The yield was 86%.
About this product, H-NMR was measured. As a result, 7.82 ppm (d), 7.69 ppm (s), 7.60-7.55 (t), and 7.44-7.37 (m) were observed as signals based on H of the phenyl ring. Assigned. Also, 4.22-4.18 ppm (t) is the CH ₂ proton adjacent to the ether bond and 2.62-2.56 ppm (t) is the CH ₂ proton adjacent to the sulfonyl group. 09-1.99 ppm (m) is attributed to an intermediate CH ₂ proton, and 3- (3′-nitrophenoxy) propanesulfonic acid Na having the chemical structural formula of the above chemical formula 21 is generated. confirmed.

(2) Synthesis of 3,3′-bis (3-sulfopropoxy) azobenzene disodium 3,3′-bis (3-sulfopropoxy) azobenzene having the chemical structural formula of the following chemical formula 22 by the procedure shown below Sodium was synthesized.

To a 100 ml four-necked flask that has been completely dried, 5.7 g (20 mmol) of 3- (3′-nitrophenoxy) propanesulfonic acid and 15 ml of water are added together with 15 ml of methanol. 6 g was added. The mixture was heated to 90 ° C. with stirring, then 5 g NaOH dissolved in 10 ml water was added dropwise into the flask. The reaction solution was stirred at 90 ° C. for 3 hours, then cooled to room temperature, the filtered filtrate was distilled off under reduced pressure, and the resulting solid was washed with ethanol, which was vacuum-dried at 60 ° C. for 20 hours, 4.4 g of an orange product having the chemical structural formula of Chemical Formula 22 was obtained. The yield was 88%.
About this product, H-NMR was measured. As a result, 7.51 ppm (m), 7.4 ppm (s), and 7.15 ppm (split) were observed and assigned as signals based on H of the phenyl ring. Proton signal of propoxy group was assigned as above. From the above results, it was confirmed that disodium 3,3′-bis (3-sulfopropoxy) azobenzene was produced.

(3) Synthesis of 3,3′-bis (3-sulfopropoxy) hydrazobenzene disodium 3,3′-bis (3-sulfopropoxy) having the following chemical structural formula Hydrazobenzene disodium was synthesized.

In a completely dried 100 ml four-necked flask, 1.5 g (3.0 mmol) of 3,3′-bis (3-sulfopropoxy) azobenzene disodium, 15 ml of water and 1.5 ml of acetic acid were added in a nitrogen atmosphere. With stirring. The reaction mixture was then heated to 90 ° C., 1.5 g of zinc powder was quickly added and the mixture was stirred for an additional hour at this temperature. After cooling to room temperature, the reaction mixture was filtered and the filtrate was evaporated under reduced pressure. The obtained solid was washed with ethanol and vacuum dried to obtain 1.32 g of an off-white solid. The yield was 87%.
About this product, H-NMR was measured. As a result, 7.25-7.15 ppm (t) and 6.77-6.62 ppm (m) were observed and assigned as signals based on H of the phenyl ring. Proton signal of propoxy group was assigned as above. From the above results, it was confirmed that disodium 3,3′-bis (3-sulfopropoxy) hydrazobenzene was produced.

(4) Synthesis of 2,2′-bis (3-sulfopropoxy) benzidine (abbreviation: 2,2′-BSPB) 2,2′-BSPB having the chemical structural formula shown below by the procedure shown below Was synthesized.

To a completely dried 100 ml four-necked flask, 1.0 g of disodium 3,3′-bis (3-sulfopropoxy) hydrazobenzene, 5 ml of water and 5 ml of concentrated hydrochloric acid are added with stirring under a nitrogen stream. It was. The mixture was heated at 100 ° C. for 2 hours and then cooled to room temperature. The produced precipitate was filtered and vacuum-dried to obtain 0.5 g of white 2,2′-BSPB having the chemical structural formula of Chemical Formula 24. The yield was 60%.
This product was subjected to H-NMR measurement in the presence of triethylamine. As a result, 6.77-6.71 ppm (d) and 6.2 ppm (s) were observed and assigned as signals based on H of the phenyl ring. 4.91 ppm (br) was assigned to two amino group protons. Also, 3.9-3.8 ppm (t) is the CH ₂ proton adjacent to the ether bond and 2.52-2.45 ppm (t) is the CH ₂ proton adjacent to the sulfonyl group. 93-1.79 ppm (m) was assigned to the intermediate CH ₂ proton, respectively. From the above results, it was confirmed that 2,2′-BSPB was generated.

(5) Preparation of moisture sensitive film made of NTDA-2,2'-BSPB / TAPB branched cross-linked sulfonated polyimide NTDA-2,2 of structural unit represented by chemical structural formula of chemical formula 25 A moisture-sensitive film made of '-BSPB / TAPB branched crosslinked sulfonated polyimide (triethylamine salt type) was prepared.

  To a completely dried 100 ml four-necked flask, 2.303 g (5 mmol) of 2,2′-BSPB, 19 g of m-cresol, and 1.56 g of triethylamine were added with stirring in a nitrogen stream. After 2,2′-BSPB was completely dissolved, 1.209 g (6 mmol) of NTDA (1,4,5,8-naphthalenetetracarboxylic dianhydride) purified by sublimation and benzoic acid 1. 06 g was added to the flask. The mixture was heated at 80 ° C. for 2 hours and then heated at 180 ° C. for 10 hours. Next, after cooling to 25 ° C., 0.267 g (0.67 mmol) of TAPB and 16.5 g of m-cresol were added, and the mixture was stirred at 70 ° C. for 2 hours and NTDA-2,2′-BSPB having a high polymerization degree. / TAPB branched cross-linked sulfonated polyamic acid solution was obtained. The total solid content concentration of the obtained uniform solution was 11% by weight. Add m-cresol to this solution and dilute to 5%. Then, this solution is applied to the support substrate 11 having the first and second comb-shaped electrodes 12 and 13 shown in FIG. 1, and this is heated at 80 ° C. for 3 hours and then in vacuum at 160 ° C. for 2 hours. A moisture sensitive film was obtained by drying treatment. The moisture sensitive film of the humidity sensor of Example 1 was subjected to a water resistance test described later and a high temperature and high humidity test, and the results are shown in FIGS. 2 and 5, respectively.

[Example 2] (Acid anhydride NTDA / diamine 3,3′-bis (3′-sulfopropoxy) benzidine (hereinafter sometimes abbreviated as 3,3′-BSPB) = 5/4)
3,3′-bis (3′-sulfopropoxy) benzidine (abbreviation: 3,3′-BSPB) was obtained in the same manner as in Example 1 except that o-nitrophenol was used instead of m-nitrophenol. Synthesized. The overall yield was 46%.
This product was subjected to H-NMR measurement in the presence of triethylamine. 6.98-6.93 ppm (s), 6.93-6.82 ppm (d), and 6.70-6.60 ppm (d) were observed and assigned to protons on the phenyl ring. 4.9-4.5 ppm (br) for amino group protons, 4.17-4.02 ppm (t) for CH ₂ protons adjacent to the ether bond, around 2.8 ppm (with triethylamine signal and (Overlapping) was assigned to the CH ₂ proton adjacent to the sulfo group, and 2.15 to 1.98 ppm (m) was assigned to the intermediate CH ₂ proton. From the attribution and integral intensity ratio, the product was confirmed to be 3,3′-BSPB.
3,3′-BSPB 1.842 g (4 mmol), NTDA 1.342 g (5 mmol), TAPB 0.267 g (0.67 mmol) were used and NTDA-3,3 ′ having a high degree of polymerization in the same manner as in Example 1. -A BSPB / TAPB branched cross-linked sulfonated polyamic acid solution was obtained. Add m-cresol to this solution and dilute to 6%. Then, this solution is applied to the support substrate 11 having the first and second comb-like electrodes 12 and 13 shown in FIG. 1, and this is heated at 80 ° C. for 3 hours and then in vacuum at 160 ° C. for 2 hours. The moisture-sensitive film of the humidity sensor was obtained by drying treatment. The moisture-sensitive film of the humidity sensor of Example 2 was subjected to a water resistance test and a high-temperature and high-humidity test described later, and almost the same results as those of Example 1 were obtained.

[Example 3] (Acid anhydride NTDA / diamine 4,4′-bis (4-aminophenoxy) biphenyl-3,3′-disulfonic acid (hereinafter sometimes abbreviated as BAPBDS) = 5/4. If)
(1) Synthesis of 4,4′-bis (4-aminophenoxy) biphenyl-3,3′-disulfonic acid (BAPBDS) 20 g of 4,4′-bis (4-aminophenoxy) biphenyl was added to 17 ml of 95% sulfuric acid. The solution was cooled to 0 ° C. and 35 ml of fuming sulfuric acid (SO ₃ 60%) was added dropwise. After stirring at 80 ° C. for 1 hour, the mixture was cooled to room temperature, poured into ice water, and the precipitated solid was separated by filtration. After dissolving in an aqueous NaOH solution, an aqueous hydrochloric acid solution was added, and the precipitated solid was separated by filtration, washed with water and dried to obtain a product. The resulting product, it was confirmed that the H-NMR or et B APBDS.

(2) Preparation of moisture sensitive film made of NTDA-BAPBDS / TAPB branched cross-linked sulfonated polyimide Example 1 using NTDA 1.342 g (5 mmol), BAPBDS 2.114 g (4 mmol), TAPB 0.341 (0.67 mmol) In the same manner as above, an NTDA-BAPBDS / TAPB branched cross-linked sulfonated polyamic acid solution having a high degree of polymerization was obtained. Add m-cresol to this solution and dilute to 6%. Then, this solution is applied to the support substrate 11 having the first and second comb-shaped electrodes 12 and 13 shown in FIG. 1, and this is heated at 80 ° C. for 3 hours and then in vacuum at 160 ° C. for 2 hours. A moisture-sensitive film was obtained by drying treatment. The moisture sensitive film of the humidity sensor of Example 3 was subjected to a water resistance test and a high temperature and high humidity test described later, and the results are shown in FIGS. 3 and 6.

[Comparative Example 1]
A polymer obtained by quaternizing ammonium polyglycidyl methacrylate with triethylamine hydrochloride is dissolved in alcohol and applied to a support substrate 11 having first and second comb electrodes 12 and 13 shown in FIG. Was dried for 2 hours to obtain a moisture sensitive film of the humidity sensor of Comparative Example 1. The moisture sensitive film of the humidity sensor of Comparative Example 1 was subjected to a water resistance test and a high temperature and high humidity test described later, and the results of the water resistance test are shown in FIG.

[Comparative Example 2] (In case of synthesis of NTDA-2,2′-BSPB polyimide))
NTDA-2,2'-BSPB polyimide is synthesized using NTDA purified by sublimation as acid anhydride and 2,2'-bis (3-sulfopropoxy) benzidine (2,2'-BSPB) as diamine containing sulfonic acid group. did. First, 2,2′-BSPB, NTDA, triethylamine, and benzoic acid are added to m-cresol so that BSPB: NTDA: triethylamine: benzoic acid = 1: 1: 2: 1.5. The solution was heated at 80 ° C. for 4 hours, and further heated at 180 ° C. for 20 hours to effect solution thermal imidization. The reaction solution was cooled to room temperature, washed reprecipitated in acetone, by which the 20 hours and vacuum dried at 60 ° C., NTDA-2 having a structural unit represented by the chemical structural formula of Chemical Formula 26 below, 2'-BSPB polyimide triethylamine salt was obtained.

  The obtained NTDA-2,2′-BSPB polyimide (triethylamine salt) was dissolved in metacresol and applied to the support substrate 11 having the first and second comb electrodes 12 and 13 shown in FIG. The film was vacuum-dried at 80 ° C. for 3 hours and then at 168 ° C. for 2 hours to obtain a humidity sensitive film of the humidity sensor of Comparative Example 2. The moisture resistance film of the humidity sensor of Comparative Example 2 was subjected to a water resistance test described later.

(Water resistance test)
The moisture resistance films of the humidity sensors of Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to a water resistance test, and the representative results are shown in FIGS. The test was performed by measuring the relative humidity dependency of the resistance value by comparing the initial value with that after dipping the moisture sensitive film in water at 25 ° C. for 24 hours. The resistance value was measured at 25 ° C. using an Agilent LCR meter 4263B. As the standard humidity generator, SRH-01 manufactured by Shinei Co., Ltd. was used.

  As apparent from the results of FIGS. 2 to 4, the moisture sensitive films of Examples 1 to 3 provided with the branched and crosslinked sulfonated polyimide as the moisture sensitive film of the humidity sensor have almost the same characteristics before and after being immersed in water. It turns out that it has high water resistance. On the other hand, in the humidity sensitive film of the humidity sensor of Comparative Example 1, the resistance value after immersion in water greatly increases, and in Comparative Example 2, the moisture sensitive film after immersion in water peels off and the resistance value increases. It is understood that the water resistance is low in any case.

(High temperature and high humidity test)
A high temperature and high humidity test was performed on the moisture sensitive films of the humidity sensors of Examples 1 to 3 and Comparative Examples 1 and 2. The test was put in a high-temperature and high-humidity tank having a temperature of 85 ° C. and a humidity of 100%, and the state of peeling of the moisture-sensitive film from each support substrate was observed before 100, 200, 300, 500, and 1000 hours. did. The moisture-sensitive membranes of Examples 1 to 3 provided with a branched and crosslinked sulfonated aromatic polyimide as the moisture-sensitive membrane of the humidity sensor are peeled off from the support substrate even in a high-temperature and high-humidity environment for a long period of 1000 hours. Such abnormalities were not confirmed. On the other hand, it was confirmed that the humidity sensitive films of the humidity sensors of Comparative Examples 1 and 2 were released from the support substrate in a relatively early time. About the moisture sensitive film | membrane of Examples 1-3, the relationship between a resistance value and relative humidity was measured at room temperature after the 1000-hour process similarly to the case of the said water resistance test. The results are shown in FIGS. In the case of Example 2, almost the same result as Example 1 was obtained. It can be seen that the moisture-sensitive films of Examples 1 to 3 have almost the same characteristics as the initial characteristics even after 1000 hours and have very excellent durability against high temperature and high humidity.

  The humidity sensor of the present invention can be used as an electric resistance type humidity sensor excellent in reproducibility without causing the moisture sensitive film to peel off from the support substrate even in a severe environment under high temperature and high humidity. .

It is explanatory drawing of the humidity sensor which concerns on one embodiment of this invention. It is a graph which shows the result of having performed the water resistance test of Example 1 of the humidity sensor. It is a graph which shows the result of having performed the water resistance test of Example 3 of the humidity sensor. 6 is a graph showing the results of a water resistance test of Comparative Example 1. It is a graph which shows the result of having performed the high temperature, high humidity test of Example 1 of the humidity sensor which concerns on one embodiment of this invention. It is a graph which shows the result of having performed the high temperature, high humidity test of Example 3 of the humidity sensor.

Explanation of symbols

  10: humidity sensor, 11: support substrate, 12: first comb electrode, 13: second comb electrode, 14: first electrode portion, 15: second electrode portion, 16: pin electrode, 17 : Insulator, 18: Branched cross-linked sulfonated polyimide membrane

Claims (6)

A humidity sensor having a plurality of electrodes formed on a support substrate and a moisture sensitive film made of a polymer electrolyte covering the electrodes,
The moisture-sensitive film has a repeating unit represented by the following chemical formula (1), and an acid-terminated sulfonated polyimide consisting of an aromatic tetracarboxylic acid component residue at both ends is branched with a trifunctional or higher functional aromatic amine compound. A humidity sensor comprising a branched and crosslinked sulfonated polyimide membrane.

[Wherein Ar ¹ and Ar ⁴ are tetravalent groups having an aromatic ring, and Ar ² is a divalent group having an aromatic ring substituted with one or more sulfonic acid groups or derivatives of sulfonic acid groups. Ar ⁵ is a divalent group having an aromatic ring that does not use a sulfonic acid group or a derivative of a sulfonic acid group as a substituent, l is an integer of 1 or more, and m is 0 or an integer of 1 or more. . ] 2. The humidity sensor according to claim 1, wherein Ar ¹ and / or Ar ^{4 in the} chemical formula (1) is composed of a branched cross-linked sulfonated polyimide which is a tetravalent group represented by the following chemical formula (2). Humidity sensor.

3. The humidity sensor according to claim 1, wherein Ar ^{2 in the} chemical formula (1) is composed of a branched cross-linked sulfonated polyimide which is a divalent group represented by the following chemical formula (3).

[Wherein D ¹ represents O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O = S═O or C═O, and R ^{1 to} R ³ each independently represent hydrogen An atom or a C1-C2 alkyl group is shown, and X shows a hydrogen atom, an alkali metal, ammonium, or a quaternary amine. ] 3. The humidity sensor according to claim 1, wherein Ar ^{2 in the} chemical formula (1) is made of a branched cross-linked sulfonated polyimide which is a divalent group represented by the following chemical formula (4).

[Wherein D ² represents O or C (CH ₃ ) ₂ , and R ^{4 to} R ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, as shown in Chemical Formula 5 below. And Ar ³ is

(In the formula, D ³ represents a direct bond, O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O = S═O or C═O, and R ^{8 to} R ¹⁰ each represents Independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, X represents a hydrogen atom, an alkali metal, ammonium or a quaternary amine, and n represents an integer of 0, 1 or 2. ] 3. The humidity sensor according to claim 1 , wherein Ar ^{2 in the} chemical formula (1) is composed of a branched cross-linked sulfonated polyimide which is a divalent group represented by the following chemical formula (5).

[Wherein R ^{11 to} R ¹³ each independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, p is an integer of 1 or 2, and n is an integer of 1 to 6. , K is an integer of 1 or 2 (provided that when k is 2, R ¹³ is not present), and X is a hydrogen atom, an alkali metal, ammonium or a quaternary amine. ]   (1) By reacting an aromatic diamine component Mb mole and an aromatic tetracarboxylic acid component Ma mole in an organic solvent in a molar ratio Ma / Mb of 1.03 to 1.5, the terminal group is An organic solvent-soluble acid-terminal sulfonated polyimide composed of an aromatic tetracarboxylic acid component residue is synthesized, and (2) the aromatic tetracarboxylic acid component at both ends of the acid-terminal sulfonated polyimide solution at a temperature of 100 ° C. or lower. A trifunctional or higher functional aromatic amine is added, mixed and reacted so that the residue and the amino group are approximately equimolar to obtain a branched sulfonated polyamic acid solution having a high polymerization degree. (3) A humidity sensor comprising a moisture-sensitive film made of a branched and cross-linked sulfonated polyimide formed by heating at a temperature of from ℃ to 300 ℃ to perform solvent removal and thermal imidization.

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