JP4127816B2 - Moisture sensitive element - Google Patents

Description

  The present invention relates to a humidity sensitive element suitable for use in a humidity sensor.

  Conventionally, in a sensor element such as a humidity sensor, an organic polymer is used as a sensor film (for example, Patent Document 1, Patent Document 2, etc.). In particular, many ion conductive polymers having a polyacrylic or polyvinyl skeleton are used.

However, for example, conventional sensor elements have a problem that heat resistance and water resistance are poor. Therefore, when designing a conventional sensor element, the problem of heat resistance and water resistance must be taken into account.
JP 59-171844 A JP-A-2-253148

  Accordingly, an object of the present invention is to provide a moisture sensitive element that does not have a problem of heat resistance or water resistance.

  As a result of intensive studies to achieve the above object, the present inventors have found that a moisture sensitive element using a sulfonated aromatic polyimide having a structure represented by the following general formulas (1) to (4) is heat resistant. In addition, the present inventors have found that the water resistance is excellent and have completed the present invention.

  That is, the moisture sensitive element of the present invention is a moisture sensitive element having a plurality of electrodes formed on a support substrate and a polyimide film as a sensor film formed in contact with the electrodes, wherein the polyimide film is It has the structural unit represented by General formula (1)-(4), It is characterized by the above-mentioned.

  That is, the moisture sensitive element of the present invention is a moisture sensitive element having a plurality of electrodes formed on a support substrate and a polyimide film as a sensor film formed in contact with the electrodes, wherein the polyimide film is It has the structural unit represented by following General formula (1), It is characterized by the above-mentioned.

Here, Ar ¹ represents a tetravalent group having at least one aromatic ring, Ar ² is a group represented by the following general formula 2,

In the above, D ¹ represents a group selected from a direct bond, O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ and S, and X represents a hydrogen atom, an alkali metal, ammonium or Represents a quaternary amine.

  Further, the moisture sensitive element of the present invention is a moisture sensitive element having a plurality of electrodes formed on a support substrate and a polyimide film as a sensor film formed in contact with the electrodes, the polyimide film being It has a structural unit represented by the following general formula (2).

Here, Ar ³ represents a tetravalent group having at least one aromatic ring, Ar ⁴ is a group represented by the following general formula 4;

In the above, D ² and D ³ each represent a group selected from O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ and S, and Ar ⁵ is represented by the following formula: A group having one selected from:

In the above, D ⁴ represents a group selected from a direct bond, O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O═S═O, S and C═O, X represents a hydrogen atom, an alkali metal, ammonium, or a quaternary amine, and n represents an integer of 0 to 2.

  Furthermore, the moisture sensitive element of the present invention is a moisture sensitive element having a plurality of electrodes formed on a support substrate and a polyimide film as a sensor film formed in contact with the electrodes, wherein the polyimide film comprises: It has a structural unit represented by the following general formula (3).

  In the above, m is an integer of 1 to 2, n is an integer of 1 to 6, k is an integer of 1 to 2, and X is a hydrogen atom, an alkali metal, ammonium or a quaternary amine. To express.

  In the moisture sensitive element including the polyimide film having the structural unit represented by the general formula (1), the polyimide film further includes a structural unit represented by the general formula (4), and the general formula (1) Is preferably 10 to 100% by weight.

Here, Ar ⁶ represents a tetravalent group having at least one or more aromatic rings, Ar ⁷ is a divalent group having at least one or more aromatic rings, and has a sulfonic acid group as a substituent. Indicates something that never happens.

  In the moisture sensitive element including the polyimide film having the structural unit represented by the general formula (2), the polyimide film further includes a structural unit represented by the general formula (4), and the general formula (2) Is preferably 10 to 100% by weight.

  In the moisture sensitive element including the polyimide film having the structural unit represented by the general formula (3), the polyimide film further includes a structural unit represented by the general formula (4), and the general formula (3) Is preferably 10 to 100% by weight.

  Since the moisture sensitive element of the present invention includes a sulfonated aromatic polyimide film as a sensor film, it has high heat resistance and high water resistance. Therefore, if the humidity sensitive element of the present invention is used, the performance is exhibited even in an environment of high temperature / high humidity and condensation, and it can be applied as various high temperature / high humidity control sensors.

  Embodiments of the present invention will be described below. The humidity sensitive element of the present invention has the following structure. FIG. 1 is a plan view of a substrate having comb-shaped electrodes used in this example. The moisture sensitive element of the present embodiment is a resistance detection type moisture sensitive element, and includes a first comb electrode 11 and a second comb electrode 12 formed on a support substrate 10. The first comb-shaped electrode 11 has 1 to 50 first electrode portions 21, and the second comb-shaped electrode 12 has 1 to 50 second electrode portions 22, and 1 to 50 first electrode portions 21. The first electrode portions 21 and 1 to 50 second electrode portions 22 are alternately formed in parallel. Conductors 13 and 13 are respectively formed at the bases of the first comb-shaped electrode 11 and the second comb-shaped electrode 12, and a connection portion between the base of the first comb-shaped electrode 11 and the conductor 13, and An insulator 14 made of glass is formed so as to cover the connection portion between the base portion of the second comb-shaped electrode 12 and the conductor 13. Pin electrodes 17 and 17 are connected to the two conductors 13 and 13, respectively. The sulfonated aromatic polyimide film 15 represented by the general formulas (1) to (4), which is a moisture-sensitive film, covers the first electrode part 21 and the second electrode part 22 and is a moisture-sensitive film. Is formed.

Here, the group represented by the chemical formula 2 constituting the general formula (1) and the group represented by the chemical formula 4 constituting the general formula (2) are derived from the structures shown in the following chemical formula 8 and chemical formula 9, respectively. Is introduced by an aromatic diamine. For the synthesis of these aromatic diamines, a synthesis method can be applied depending on the structure. An aromatic diamine having a structure represented by Chemical Formula 8 is converted to a sulfate by using the raw material diamine as a sulfate, and then sulfonated by the method described in Hosoda, “Theoretical Manufacturing Dye Chemistry”, published by Gihosha, Tokyo, 1957, etc. Can be synthesized. At this time, the raw material diamine used is one in which the aromatic ring is directly bonded, and O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , and S are sandwiched therebetween. , Benzidine, 3,4'-oxydianiline, 4,4'-oxydianiline, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'- Dimethyl-4,4′-diaminodiphenylmethane, 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 ( - aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'-like diaminodiphenyl sulfide may be mentioned.

Ar ⁵ in Chemical Formula 9 is a structure shown above Chemical Formula ⁵ , that is, a structure in which an aromatic ring not bonded to an amino group is bonded to an electron withdrawing group, and D ⁴ is a direct bond, O, CH _In the case of a sulfonic acid group-containing aromatic diamine that is ₂ , C (CH ₃ ) ₂ , S, or C (CF ₃ ) ₂ , for example, (1) Raw material diamine in concentrated sulfuric acid or fuming sulfuric acid, “Manufacturing dye chemistry”, published by Gihosha, Tokyo, 1957, the method of sulfonation, (2) dihydric phenol in concentrated sulfuric acid or fuming sulfuric acid, Hosoda, “Theoretical manufacturing dye chemistry”, Gihosha After the sulfonation by a method described in Tokyo, 1957, etc., a dinitro compound is synthesized by reacting with an aromatic halide having a nitro group by a method described in JP-A-9-241225. Return nitro group of compound How to diamine compounds by, it can be synthesized by such.

  The diamine used as a raw material in the above method (1) is one in which an aromatic ring to which no amino group is bonded 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, 2, 2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, α, α′-bis (4-aminophenyl) -1,4-diisopropylbenzene, 1,5-bis (4-aminophenoxy) naphthalene And so on.

  Examples of the dihydric phenol that can be used as a raw material in the above-described method (2) are those in which an aromatic ring is not bonded to an electron withdrawing group. For example, 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, Scan (2-hydroxy-5-methylphenyl) methane, 1,5-dihydroxynaphthalene and the like. Examples of the aromatic halide having a nitro group include 2-chloronitrobenzene, 3-chloronitrobenzene, 4-chloronitrobenzene, 2-fluoronitrobenzene, 3-fluoronitrobenzene, 4-fluoronitrobenzene, and 5-fluoro-2-nitrotoluene. Can be mentioned.

Ar ⁵ in the chemical formula 9 is a structure shown on the upper side of chemical formula 5, that is, a structure in which an aromatic ring not bonded to an amino group is not bonded to an electron withdrawing group, and D ⁴ is O═S═O or In the case of a sulfonic acid group-containing aromatic diamine in which C═O, for example, (3) dihydric phenol in fuming sulfuric acid, as described in Hosoda, “Theoretical Manufacturing, Dye Chemistry”, published by Gihosha, Tokyo, 1957, etc. After sulfonation by the method, a dinitro compound is synthesized by reacting with an aromatic halide having a nitro group by a method described in JP-A-9-241225 and the like, and then the nitro group of the dinitro compound is reduced. It can be synthesized by a method of forming a compound.

  Examples of the dihydric phenol that can be used as a raw material in the above method (3) are those in which an aromatic ring is bonded to an electron withdrawing group, and examples thereof include bis (4-hydroxyphenyl) sulfone and bis (4-hydroxy). Phenyl) ketone and the like, and examples of the aromatic halide having a nitro group include those described above.

In the case of a sulfonic acid group-containing aromatic diamine having a structure in which Ar ⁵ in Chemical Formula 9 is shown below Chemical Formula ⁵ , that is, a fluorene ring skeleton to which an amino group is not bonded, for example, (4) It can be synthesized by converting to sulfate in concentrated sulfuric acid, and then sulfonating with fuming sulfuric acid by the method described in Hosoda, “Theoretical Manufacturing Dye Chemistry”, published by Gihosha, Tokyo, 1957, and the like. In this case, examples of the raw material diamine used include 9,9-bis (4-aminophenyl) fluorene and 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene.

  The alkali metal salt of the aromatic diamine used in the present invention can be easily synthesized by reacting with an alkali metal hydroxide, carbonate, hydrogencarbonate and halogen salt, and the reaction is sulfonated aromatic diamine. The synthesis may be performed either during synthesis, after synthesis, or after synthesis of polyimide described later. Examples of the alkali metal include lithium, potassium, sodium, cesium and the like.

  Examples of the aromatic tetracarboxylic acid component used for the synthesis of the sulfonated aromatic polyimide in the present invention include 3,3 ′, 4,4′-biphenyltetracarboxylic acid and 2,3 ′, 3,4′-biphenyltetracarboxylic acid. Acid, 3,3 ′, 4,4′-benzophenone 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 or their acid dianhydrides and esterified products Can be mentioned. Among these, 1,4,5,8-naphthalenetetracarboxylic acid or acid dianhydride or esterified product thereof is preferable from the viewpoint of durability.

  The synthesis of the sulfonated aromatic polyimide in the present invention is not particularly limited. JP-A-6-87957, JP-A-10-168188, JP-A-8-333451, JP-A-8-333452, JP It can be synthesized by known methods described in, for example, 8-333453 and JP 2000-510511.

  The sulfonated aromatic polyimide in the present invention can be synthesized using an ω-sulfoalkoxy group-containing aromatic diamine having a structure represented by the following chemical formula 10 as a diamine component.

  The ω-sulfoalkoxy group-containing aromatic diamine having the structure represented by the chemical formula 10 includes, for example, (5) reacting an aromatic dinitro compound having a hydroxyl group with an alkali metal halide alkyl sulfonate to obtain ω-sulfoalkoxy. A method of obtaining an ω-sulfoalkoxy group-containing aromatic diamine by synthesizing an aromatic dinitro compound having a group, and (6) an aromatic mononitro compound having a hydroxyl group and an alkali metal halide alkyl halide, In which an aromatic mononitro compound having an ω-sulfoalkoxy group is synthesized, followed by an azo coupling reaction followed by a reduction or rearrangement reaction to obtain an ω-sulfoalkoxy group-containing aromatic diamine. It can be adjusted by a synthesis method according to the structure.

  In the synthesis method (5) 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 salt of an aromatic dinitro compound having a hydroxyl group. And a halogenated alkylsulfonic acid alkali metal salt in a polar solvent such as N, N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and the like, can be synthesized at 50 to 140 ° C. for 1 to 80 hours.

  The aromatic dinitro 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-dinitroresorcinol, 3,5-dinitrocatechol, 2,5-dinitrohydroquinone, 4,4'-dihydroxy- (3,3'-dinitro) biphenyl 2,2′-dihydroxy- (5,5′-dinitro) biphenyl and the like can be preferably mentioned.

  The alkali metal salt of an aromatic dinitro compound having a hydroxyl group is obtained by using, in the polar solvent, an aromatic dinitro compound having a hydroxyl group and potassium carbonate or sodium carbonate, etc., using 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 produced water by azeotropy.

  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-bromobutanesulfone. Preferred examples include potassium, sodium, and lithium salts such as acids.

  In the synthesis method (5) 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 edited by the Chemical Society of Japan, New Experimental Chemistry Course 15, Oxidation and Reduction. II, Maruzen, 1975 (p.22, 433-435), and the like can be used. For example, this can be achieved by hydrogenation using Pd / C.

  The aromatic mononitro compound having a hydroxyl group used in the synthesis method (6) of the ω-sulfoalkoxy group-containing aromatic diamine is an aromatic mononitro compound having at least one hydroxyl group, such as m-nitrophenol, Preferred examples include o-nitrophenol.

  In the synthesis method (6) of the ω-sulfoalkoxy group-containing aromatic diamine, the aromatic mononitro compound having a ω-sulfoalkoxy group comprises an aromatic mononitro compound having a hydroxyl group and an alkali metal halide alkyl sulfonate. The ω-sulfoalkoxy group-containing aromatic diamine can be synthesized by reacting in the same manner as described in the method (5).

  In this synthesis method (6), the azo coupling reaction and subsequent rearrangement reaction are described in the Chemical Society of Japan, New Experimental Chemistry Course 15, Oxidation and Reduction II, Maruzen, 1975 (p.23, 24, 67, 68). 4th edition, Experimental Chemistry Course 20, Organic Synthesis II, Maruzen, 1992, p. 302, etc. can be used. For example, heating in Zn / NaOH / methanol-water to azobenzene, then heating in Zn / ethanol-ammonia to hydrazobenzene. This is achieved by heating in concentrated hydrochloric acid to effect benzidine transition.

  The ω-sulfoalkoxy group-containing aromatic diamine having the structure represented by Chemical Formula 10 used for the synthesis of the alkoxysulfonated aromatic polyimide of the present invention is not particularly limited. -(2,4-diaminophenoxy) propanesulfonic acid, 4- (2,4-diaminophenoxy) butanesulfonic acid, 3- (2,5-diaminophenoxy) propanesulfonic acid, 4- (2,5-diaminophenoxy) ) Butanesulfonic acid, 1,2-bis (3-sulfopropoxy) 3,5-diaminobenzene, 1,2-bis (4-sulfobutoxy) 3,5-diaminobenzene, 1,5-bis (3-sulfo) Propoxy) 2,4-diaminobenzene, 1,5-bis (4-sulfobutoxy) 2,4-diaminobenzene, 1,4-bis (3-sulfo) (Ropoxy) 2,5-diaminobenzene, 1,4-bis (4-sulfobutoxy) 2,5-diaminobenzene, 4,4′-bis (3-sulfopropoxy) 3,3′-diaminobiphenyl, 2,2 '-Bis (3-sulfopropoxy) 5,5'-diaminobiphenyl, 2,2'-bis (3-sulfopropoxy) benzidine, 2,2'-bis (4-sulfobutoxy) benzidine, 3,3'- Bis (3-sulfopropoxy) benzidine and 3,3′-bis (4-sulfobutoxy) benzidine can be preferably mentioned, and in particular, 2,2′-bis (3-sulfopropoxy) benzidine and 2,2 ′ -Bis (4-sulfobutoxy) benzidine is preferred because of the proton conductivity and water resistance of the resulting alkoxysulfonated polyimide.

  The aromatic tetracarboxylic acid component used for the synthesis of the sulfonated aromatic polyimide of the present invention is not particularly limited, and examples thereof include 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3 ', 3,4'-biphenyltetracarboxylic acid, 3,3', 4,4'-benzophenone tetracarboxylic acid, 3,3 ', 4,4'-diphenyl ether tetracarboxylic acid, bis (3,4-di Carboxyphenyl) 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 or their acid dianhydrides Mention may be made of the ester product.

  As the aromatic tetracarboxylic acid component used for the synthesis of the alkoxysulfonated aromatic polyimide of the present invention, 1,4,5,8-naphthalenetetracarboxylic acid or acid dianhydride or esterified product thereof was obtained. The water resistance of the alkoxysulfonated polyimide is particularly suitable.

  In the sulfonated aromatic polyimide in the present invention, a diamine component having no sulfo group as a substituent may be used in combination with the aromatic diamine component having the structure represented by the chemical formulas 8 to 10 as the diamine component. .

  That is, the sulfonated aromatic polyimide of the present invention includes a structural unit represented by the following general formula (4) and a structural unit represented by the following general formula (1) to (3). It does not matter.

Here, Ar ⁶ is a tetravalent group having at least one or more aromatic rings, and Ar ⁷ is a divalent group having at least one or more aromatic rings and does not have a sulfo group as a substituent. It is.

  In the sulfonated aromatic polyimide of the present invention, the structural units represented by the general formulas (1) to (3) are each 1 to 100% by weight, preferably 10 to 100% by weight, and further 50 to 100% by weight based on the total weight. %, In particular 70 to 100% by weight.

  In the sulfonated aromatic polyimide of the present invention, when the structural unit represented by the general formulas (1) to (3) is less than 1% by weight with respect to the total weight, characteristics such as ion exchange capacity and proton conductivity are exhibited. Since it becomes difficult, it is not preferable. The structure of the copolymerized sulfonated aromatic polyimide containing the structural unit represented by the general formula (4) is a random copolymer and / or a block copolymer.

  The aromatic tetracarboxylic acid component forming the structural unit represented by the general formula (4) is the same aromatic tetracarboxylic acid as the aromatic tetracarboxylic acid forming the structural units of the general formulas (1) to (3). Carboxylic acid can be preferably used. The aromatic diamine forming the structural unit represented by the general formula (4) is an aromatic diamine having no sulfo group as a substituent, and examples thereof include paraphenylene diamine, metaphenylene diamine, and 4,4 ′. -Oxydianiline, 3,4'-oxydianiline, 9,9-bis (4-aminophenyl) fluorene, 3,3'-bis (3-aminophenyl) sulfone, 4,4'-bis (3- Aminophenoxy) diphenylsulfone, 2,2′-trifluoromethylbenzidine and the like can be preferably mentioned.

  The alkoxysulfonated aromatic polyimide of the present invention can be easily performed by a conventionally known method using the aromatic tetracarboxylic acid component and the aromatic diamine component.

  Specifically, for example, in a polar solvent, the diamine and the aromatic tetracarboxylic dianhydride, a tertiary amino compound, toluene or xylene as an azeotropic solvent is added, and heated to 140 to 220 ° C. It can be easily achieved by performing the condensation polymerization reaction for 0.5 to 100 hours while removing the water together with the azeotropic solvent. Examples of the tertiary amino compound used at this time include trimethylamine and triethylamine. If necessary, benzoic acid, isoquinoline and the like may be added as a catalyst. The molar ratio of the amino group of the aromatic diamine and the aromatic tetracarboxylic dianhydride to the acid dianhydride group is preferably in the range of 0.95 to 1.05. This is not preferable because the strength of the resulting film is lowered when the molecular weight of the polyimide is lowered. An amine salt-type sulfonated polyimide can be obtained by the above condensation polymerization method, and a proton-type sulfonated polyimide can be easily obtained by immersing this in an aqueous hydrochloric acid solution and performing ion exchange. Further, by immersing an amine salt type or proton type sulfonated polyimide in an alkali metal salt or ammonium salt aqueous solution and performing ion exchange, an alkali metal salt or ammonium salt type sulfonated polyimide can be easily obtained.

  Examples of the present invention and comparative examples will be described below. In addition, the moisture sensitive element shown in each Example and Comparative Example has the first electrode portion 21 and the second electrode so that the resistance between the two pin electrodes 17 and 17 in FIG. The number of electrode portions 22 and the distance between them are set.

(Example 1)
<BDSA, NTDA>
BDSA (2,2′-benzidine disulfonic acid) and NTDA (naphthalene-1,4,5,8-tetracarboxylic dianhydride) were purchased from Tokyo Chemical Industry Co., Ltd. I used something.

<Synthesis of NTDA-BDSA polyimide>
NTDA purified by sublimation as an acid anhydride and BDSA purified by refluxing with hot water as a sulfonic acid group-containing diamine were used.

  First, BDSA was vacuum-dried at 120 ° C. for 6 hours or more to remove moisture. In m-cresol, dried BDSA, NTDA, triethylamine, and benzoic acid are added and dissolved in a molar ratio of BDSA: NTDA: triethylamine: benzoic acid = 1: 1: 2: 1.5. After heating at 80 ° C. for 4 hours, the solution was further heated at 180 ° C. for 20 hours to effect solution thermal imidization. The reaction solution was cooled to room temperature, washed by precipitation in acetone, and vacuum-dried at 80 ° C. for 20 hours to obtain an NTDA-BDSA triethylamine salt having the structural unit shown in Chemical formula 11.

<Production of moisture-sensitive element>
The obtained NTDA-BDSA triethylamine salt was dissolved in dimethyl sulfone oxide (DMSO). This solution was applied to a substrate having a comb-shaped electrode shown in FIG. 1, and this was vacuum-dried at 80 ° C. for 10 hours to obtain a moisture sensitive element of this example.

  The moisture-sensitive element (triethylamine type) of this example was subjected to a water resistance test and a high temperature resistance test described later, and the results are shown in FIGS. 2 and 10, respectively.

(Example 2)
<Synthesis of 4,4′-oxydianiline-2,2′-disulfonic acid (ODADS)>
After dissolving 20 g of 4,4′-oxydianiline in 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 obtained product was confirmed to be 4,4′-oxydianilic acid having the structure of Chemical Formula 12 by H-NMR.

<Synthesis of NTDA-ODADS polyimide>
NTDA purified by sublimation as an acid anhydride and ODADS as a sulfonic acid group-containing diamine were used. First, ODADS was vacuum-dried at 120 ° C. for 6 hours or more to remove moisture. ODADS dried in m-cresol, NTDA, triethylamine, and benzoic acid were added and dissolved so that ODADS: NTDA: triethylamine: benzoic acid = 1: 1: 2: 1.5, and 80 ° C. And then heated at 180 ° C. for 20 hours to effect solution thermal imidization. The reaction solution was cooled to room temperature, precipitated and washed in acetone, and vacuum-dried at 80 ° C. for 20 hours to obtain an NTDA-ODADS triethylamine salt having the structural unit shown in Chemical formula 13.

<Production of moisture-sensitive element>
The obtained NTDA-ODADS triethylamine salt was dissolved in DMSO. This solution was applied to a substrate having a comb-shaped electrode shown in FIG. 1, and this was vacuum-dried at 80 ° C. for 10 hours to obtain a moisture sensitive element of this example.

  The moisture-sensitive element (triethylamine type) of this example was subjected to a water resistance test and a high temperature resistance test, which will be described later, and the results are shown in FIGS. 3 and 11, respectively.

(Example 3)
<Synthesis of 3- (3′-nitrophenoxy) propane sulfonic acid sodium salt>
In the following procedure, 3- (3′-nitrophenoxy) propanesulfonic acid sodium salt of the following chemical formula 14 was 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 under a nitrogen atmosphere. After m-nitrophenol was dissolved, 20 g (150 mmol) of potassium carbonate and 20 ml of toluene were added. The reaction mixture was stirred at room temperature for 30 minutes, and then heated and refluxed for 2 hours. The reaction mixture was cooled again to room temperature, 22.5 g (100 mmol) of sodium 3-bromopropanesulfonate was added in one portion and reheated to 110 ° C. and held at this temperature for 24 hours. Next, after cooling to room temperature, the dark orange reaction liquid was filtered, and the precipitate separated by filtration was washed with acetone and then vacuum-dried at 40 ° C. for 10 hours. To the obtained solid, 300 ml of DMSO was added, the mixture was stirred at room temperature for 30 minutes, 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 purified by recrystallization from methanol to obtain 24 g of sodium 3- (3′-nitrophenoxy) propanesulfonate of Chemical formula 14 Salt was obtained. 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, 2.62-2.56 ppm (t) is the CH ₂ proton adjacent to the sulfone group, 2.09- 1.99 ppm (m) was assigned to each intermediate CH ₂ proton. From the assignment and integral intensity ratio, it was confirmed that the product had the structure of

<Synthesis of 3,3′-bis (3-sulfopropoxy) azobenzene disodium salt>
In the following procedure, 3,3′-bis (3-sulfopropoxy) azobenzene disodium salt represented by the following chemical formula 15 was synthesized.

  To a completely dried four-necked flask, 5.7 g (20 mmol) of sodium 3,3′-bis (3-nitrophenoxy) propane sulfonate, 15 ml of water and 15 ml of methanol were added, and zinc powder was added while flowing nitrogen. 4.6 g was added. The mixture was heated to 90 ° C. with stirring, and then 5 g of sodium hydroxide dissolved in 10 ml of water was dropped into the flask. The reaction mixture 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 was obtained. The yield was 88%.

  H-NMR was measured for this product. 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. The signal of the proton of the propoxy group was assigned as described above. From the assignment and integral intensity ratio, it was confirmed that the product had a chemical structure of

<Synthesis of 3,3′-bis (3-sulfopropoxy) hydrazobenzene disodium salt>
According to the following procedure, 3,3′-bis (3-sulfopropoxy) hydrazobenzene disodium salt represented by the following chemical formula 16 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 placed in a nitrogen atmosphere. And added with stirring. The reaction mixture was then heated to 90 ° C., 1.5 g of zinc powder was quickly added and the reaction mixture was stirred for an additional hour at this temperature. After cooling to room temperature, the reaction mixture was filtered and the solvent was removed from the filtrate under reduced pressure. The obtained solid was washed with ethanol and then vacuum-dried to obtain 1.32 g of an off-white solid product. 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. The signal of the proton of the propoxy group was assigned as described above. From the assignment and integral intensity ratio, it was confirmed that the product had a chemical structure of

<Synthesis of 2,2′-bis (3-sulfopropoxy) benzidine (BSPB)>
2,2′-bis (3-sulfopropoxy) benzidine represented by the following chemical formula 17 was synthesized by the following procedure.

  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 (yield 60%) of white BSPB shown in Chemical formula 18.

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 sulfone group. 1.79 ppm (m) was assigned to each intermediate CH ₂ proton. From the assignment and integral intensity, it was confirmed that the product had a chemical structure of

<Synthesis of NTDA-BSPB polyimide>
NTDA-BSPB polyimide was synthesized using NTDA purified by sublimation as an acid anhydride and 2,2′-bis (3-sulfopropoxy) benzidine (BSPB) as a diamine containing sulfonic acid group. First, BSPB, NTDA, triethylamine, and benzoic acid are added and dissolved in m-cresol so that BSPB: NTDA: triethylamine: benzoic acid = 1: 1: 2: 1.5. After heating at 4 ° C. for 4 hours, the solution was further heated at 180 ° C. for 20 hours to effect solution thermal imidization. The reaction solution was cooled to room temperature, washed by reprecipitation in acetone, and vacuum-dried at 60 ° C. for 20 hours to obtain an NTDA-BSPB polyimide triethylamine salt having the structural unit shown in Chemical formula 18.

<Production of moisture-sensitive element>
The obtained NTDA-BSPB polyimide triethylamine salt was dissolved in DMSO. This diluted solution was applied to a substrate having a comb-shaped electrode shown in FIG. 1, and this was vacuum-dried at 80 ° C. for 10 hours to obtain a moisture sensitive element of this example.

  The moisture-sensitive element (triethylamine type) of this example was subjected to a water resistance test, a high temperature resistance test and a high temperature and high humidity test described later, and the results are shown in FIGS. 4, 12 and 18.

  In Example 1-3, the sulfonated polyimide was applied to the electrode in the form of triethylamine salt, but it can be used in the proton type, ammonium type, sodium type, etc. as follows.

Example 4
The fiber-like NTDA-ODADS triethylamine salt synthesized in Example 2 was immersed in a 1N hydrochloric acid aqueous solution for 1 day or in a saturated aqueous ammonium chloride solution for 2 days, and ion-exchanged into a proton type and an ammonium salt type, respectively. This fiber-like polyimide is washed with water and dried, then dissolved in DMSO, the solution is applied to a substrate having a comb-shaped electrode shown in FIG. 1, and dried at 80 ° C. for 10 hours to obtain proton type and ammonium type NTDA-ODADS moisture sensitive elements. Obtained. Since sodium type NTDA-ODADS does not have an appropriate solvent, a triethylamine salt type polyimide is made from a DMSO solution, and then dipped in a saturated aqueous solution of sodium chloride for 2 days for ion exchange. An ODADS moisture sensitive element was obtained.

  The film was cast on a glass plate by the same production method, and the ionic conductivity of each film was measured. The result is shown in FIG. As can be seen from the figure, the ionic conductivity is improved as compared with the triethylamine salt, which is preferable as a moisture sensitive film.

  Each of the proton type, ammonium type and sodium salt type moisture sensitive elements of this example was subjected to a water resistance test described later, and the results are shown in FIGS. Moreover, the high temperature resistance test mentioned later was done about each of the proton type, ammonium type, and sodium salt type moisture sensitive element of a present Example, and the result was shown in FIGS. 13-15, respectively.

(Example 5)
As in Example 3, the NTDA-BSPB triethylamine salt synthesized in Example 3 was dissolved in DMSO, and the solution was applied to a substrate having a comb-shaped electrode shown in FIG. Obtained. This was immersed in a 1N aqueous hydrochloric acid solution for 1 day for ion exchange to obtain a proton type NTDA-BSPB moisture sensitive element.

  The moisture sensitive element (proton type) of this example was subjected to a water resistance test and a high temperature resistance test, which will be described later, and the results are shown in FIGS. 8 and 16, respectively.

(Comparative example)
A polymer obtained by quaternizing ammonium glycidyl methacrylate with triethylamine hydrochloride is dissolved in alcohol, applied to a substrate having a comb-shaped electrode shown in FIG. 1, and dried at 165 ° C. for 2 hours to obtain a humidity sensitive element of a comparative example. It was.

  The moisture-sensitive element of this comparative example was subjected to a water resistance test, a high temperature resistance test, and a high temperature high humidity test described later, and the results are shown in FIGS. 9, 17 and 19, respectively.

(Water resistance test)
A humidity resistance test was performed on the moisture sensitive elements of Examples 1 to 5 and the comparative example, and the results are shown in FIGS. The test was performed by measuring the relative humidity dependence of the resistance value between the initial stage and after the moisture-sensitive element was immersed in water at 25 ° C. for 24 hours. The resistance value was measured using an Agilent LCR meter 4263B. As the standard humidity generator, SRH-01 manufactured by Shinei Co., Ltd. was used.

  As is apparent from the results of FIGS. 2 to 9, the moisture sensitive elements of Examples 1 to 5 provided with a sulfonated aromatic polyimide film as a sensor film hardly change before and after immersion in water, and have high water resistance. It turns out that it has sex. In contrast, in the humidity sensitive element of the comparative example, it can be seen that the resistance value after immersion in water increases and the water resistance is low.

(High temperature resistance test)
About the humidity sensitive element of Examples 1-5 and a comparative example, the high temperature-proof test was done and the result was shown in FIGS. The test was performed by measuring the relative humidity dependence of the resistance value by comparing the initial value with that after leaving the humidity sensitive element in a high temperature bath at 165 ° C. for 100 hours. The resistance value was measured using an Agilent LCR meter 4263B. As the standard humidity generator, SRH-01 manufactured by Shinei Co., Ltd. was used.

  As is apparent from the results of FIGS. 10 to 17, the moisture sensitive elements of Examples 1 to 5 having a sulfonated aromatic polyimide film as a sensor film hardly change before and after the test and have high heat resistance. I understand that On the other hand, in the humidity sensitive element of the comparative example, it can be seen that the resistance value after the test increases and the heat resistance is low.

(High temperature and high humidity test)
The NTDA-BSPB triethylamine salt synthesized in Example 3 was dissolved in DMSO, and the solution was cast on a glass plate and dried at 80 ° C. for 10 hours to obtain a film. This was immersed in a 1N aqueous hydrochloric acid solution for 1 day for ion exchange to obtain a proton-type NTDA-BSPB film. The film was immersed in hot water at 80 ° C. for a predetermined time, and the conductivity was measured in 60 ° C. and 80 ° C. water.

  As a comparative example, a polymer obtained by quaternizing ammonium glycidyl methacrylate with triethylamine hydrochloride is dissolved in alcohol, the solution is cast on a glass plate, dried at 80 ° C. for 10 hours, and dried at 65 ° C. for 2 hours. The humidity sensitive element of the comparative example was obtained. After immersing this film in hot water at 80 ° C. and 60 ° C. for a predetermined time, the conductivity was measured in water at 60 ° C. and 80 ° C., respectively.

  The results are shown in FIGS. It can be seen that the film obtained by treating the film of Example 3 does not change the conductivity of the film even when immersed in hot water at 80 ° C. for 200 hours or more and is excellent in high-temperature and high-humidity resistance at high temperatures. On the other hand, it can be seen that the film of the comparative example has a sharp decrease in conductivity and low resistance to high temperature and high humidity.

It is a top view which shows an example of the structure of the moisture sensitive element which has a comb-shaped electrode of this invention. It is a figure which shows the result of having done the moisture resistance test about the moisture sensitive element of Example 1. FIG. It is a figure which shows the result of having done the moisture resistance test about the moisture sensitive element of Example 2. FIG. It is a figure which shows the result of having done the moisture resistance test about the moisture sensitive element of Example 3. FIG. It is a figure which shows the result of having done the moisture resistance test about the proton-type moisture sensitive element of Example 4. FIG. It is a figure which shows the result of having done the moisture resistance test about the ammonium type moisture sensitive element of Example 4. FIG. It is a figure which shows the result of having done the moisture resistance test about the sodium salt type moisture sensitive element of Example 4. FIG. It is a figure which shows the result of having done the moisture resistance test about the moisture sensitive element of Example 5. FIG. It is a figure which shows the result of having done the moisture resistance test about the moisture sensitive element of the comparative example. It is a figure which shows the result of having done the high temperature resistance test about the moisture sensitive element of Example 1. FIG. It is a figure which shows the result of having done the high temperature resistance test about the moisture sensitive element of Example 2. FIG. It is a figure which shows the result of having done the high temperature-proof test about the moisture sensitive element of Example 3. FIG. It is a figure which shows the result of having done the high temperature resistance test about the proton-type moisture sensitive element of Example 4. FIG. It is a figure which shows the result of having done the high temperature resistance test about the ammonium type moisture sensitive element of Example 4. FIG. It is a figure which shows the result of having done the high temperature resistance test about the sodium salt type moisture sensitive element of Example 4. FIG. It is a figure which shows the result of having done the high temperature resistance test about the moisture sensitive element of Example 5. FIG. It is a figure which shows the result of having performed the high temperature-proof test about the moisture sensitive element of the comparative example. It is a figure which shows the result of having done the high temperature, high humidity test about the proton type moisture sensitive element of Example 3. FIG. It is a figure which shows the result of having performed the high temperature, high humidity test about the humidity sensitive element of the comparative example. It is a figure which shows the result of having measured the ionic conductivity of the cast film of the proton type, ammonium type, and sodium salt type of Example 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Support substrate 11 1st comb electrode 12 2nd comb electrode 13 Conductor 14 Insulator 17 Pin electrode 21 1st electrode part 22 2nd electrode part

Claims (6)

A moisture sensitive element having a plurality of electrodes formed on a support substrate and a polyimide film as a sensor film formed in contact with the electrodes,
The said polyimide film has a structural unit represented by following General formula (1), The moisture sensitive element characterized by the above-mentioned.

(Here, Ar ¹ represents a tetravalent group having at least one aromatic ring, Ar ² is a group represented by the following general formula 2;

In the above, D ¹ represents a group selected from a direct bond, O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ and S, and X represents a hydrogen atom, an alkali metal, ammonium or Represents a quaternary amine. ) A moisture sensitive element having a plurality of electrodes formed on a support substrate and a polyimide film as a sensor film formed in contact with the electrodes,
The humidity sensitive element, wherein the polyimide film has a structural unit represented by the following general formula (2).

(Here, Ar ³ represents a tetravalent group having at least one aromatic ring, Ar ⁴ is a group represented by the following general formula 4;

In the above, D ² and D ³ each represent a group selected from O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ and S, and Ar ⁵ is represented by the following formula: A group having one selected from:

In the above, D ⁴ represents a group selected from a direct bond, O, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O═S═O, S and C═O, X represents a hydrogen atom, an alkali metal, ammonium, or a quaternary amine, and n represents an integer of 0 to 2. ) A moisture sensitive element having a plurality of electrodes formed on a support substrate and a polyimide film as a sensor film formed in contact with the electrodes,
The moisture sensitive element, wherein the polyimide film has a structural unit represented by the following general formula (3).

(In the above, m is an integer of 1 to 2, n is an integer of 1 to 6, k is an integer of 1 to 2, and X is a hydrogen atom, an alkali metal, ammonium or a quaternary amine. Represents.) The polyimide film further includes a structural unit represented by the general formula (4), and the structural unit represented by the general formula (1) is 10 to 100% by weight. Humidity sensitive element.

(Wherein Ar ⁶ represents a tetravalent group having at least one or more aromatic rings, Ar ⁷ is a divalent group having at least one or more aromatic rings, and a sulfonic acid group as a substituent. (Indicates what you do not have.)   The polyimide film further includes a structural unit represented by the general formula (4), and the structural unit represented by the general formula (2) is 10 to 100% by weight. Humidity sensitive element. The polyimide film further includes a structural unit represented by the general formula (4), and the structural unit represented by the general formula (3) is 10 to 100% by weight. Humidity sensitive element.

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