JP2004025672A - Manufacturing method for proton conductive film and proton conductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proton conductive film reduced in the residual amount of an organic solvent used when the film is manufacture by a solution casting method. <P>SOLUTION: In the manufacturing method for the proton conductive film, a film is formed by a casting method using a solution wherein a proton conductive polymer is dissolved in the organic solvent soluble in water and the obtained undried film is dipped in water before dried. <P>COPYRIGHT: (C)2004,JPO

Description

【００１９】
式（Ａ）中、Ｒ〜Ｒ’は互いに同一でも異なっていてもよく、フッ素原子を除くハロゲン原子または−ＯＳＯ_２Ｚ（ここで、Ｚはアルキル基、フッ素置換アルキル基またはアリール基を示す。）で表される基を示す。
Ｚが示すアルキル基としてはメチル基、エチル基などが挙げられ、フッ素置換アルキル基としてはトリフルオロメチル基などが挙げられ、アリール基としてはフェニル基、ｐ−トリル基などが挙げられる。
【００２０】
Ｒ^１〜Ｒ^８は互いに同一でも異なっていてもよく、水素原子、フッ素原子、アルキル基、フッ素置換アルキル基、アリル基およびアリール基からなる群より選ばれた少なくとも１種の原子または基を示す。
アルキル基としては、メチル基、エチル基、プロピル基、ブチル基、アミル基、ヘキシル基などが挙げられ、メチル基、エチル基などが好ましい。
【００２１】
フッ素置換アルキル基としては、トリフルオロメチル基、パーフルオロエチル基、パーフルオロプロピル基、パーフルオロブチル基、パーフルオロペンチル基、パーフルオロヘキシル基などが挙げられ、トリフルオロメチル基、ペンタフルオロエチル基などが好ましい。
アリル基としては、プロペニル基などが挙げられ、
アリール基としては、フェニル基、ペンタフルオロフェニル基などが挙げられる。
【００２２】
Ｘは２価の電子吸引性基を示し、電子吸引性基としては、例えば−ＣＯ−、−ＣＯＮＨ−、−（ＣＦ_２）_ｐ−（ここで、ｐは１〜１０の整数である）、−Ｃ（ＣＦ_３）_２−、−ＣＯＯ−、−ＳＯ−、−ＳＯ_２−などが挙げられる。
なお、電子吸引性基とは、ハメット（Ｈａｍｍｅｔｔ）置換基常数がフェニル基のｍ位の場合、０．０６以上、ｐ位の場合、０．０１以上の値となる基をいう。
【００２３】
Ｙは２価の電子供与性基を示し、電子供与性基としては、例えば−Ｏ−、−Ｓ−、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−および下記式
【００２４】
【化２】

【００２５】
で表される基などが挙げられる。
ｎは０または正の整数であり、上限は通常１００、好ましくは８０である。
上記一般式（Ａ）で表されるモノマーとして具体的には、例えば４，４’−ジクロロベンゾフェノン、４，４’−ジクロロベンズアニリド、ビス（クロロフェニル）ジフルオロメタン、２，２−ビス（４−クロロフェニル）ヘキサフルオロプロパン、４−クロロ安息香酸−４−クロロフェニル、ビス（４−クロロフェニル）スルホキシド、ビス（４−クロロフェニル）スルホン、これらの化合物において塩素原子が臭素原子またはヨウ素原子に置き換わった化合物、さらにこれらの化合物において４位に置換したハロゲン原子が３位に置換した化合物などが挙げられる。
【００２６】
また上記一般式（Ａ）で表されるモノマーとして具体的には、例えば４，４’−ビス（４−クロロベンゾイル）ジフェニルエーテル、４，４’−ビス（４−クロロベンゾイルアミノ）ジフェニルエーテル、４，４’−ビス（４−クロロフェニルスルホニル）ジフェニルエーテル、４，４’−ビス（４−クロロフェニル）ジフェニルエーテルジカルボキシレート、４，４’−ビス〔（４−クロロフェニル）−１，１，１，３，３，３−ヘキサフルオロプロピル〕ジフェニルエーテル、４，４’−ビス〔（４−クロロフェニル）−１，１，１，３，３，３−ヘキサフルオロプロピル〕ジフェニルエーテル、４，４’−ビス〔（４−クロロフェニル）テトラフルオロエチル〕ジフェニルエーテル、これらの化合物において塩素原子が臭素原子またはヨウ素原子に置き換わった化合物、さらにこれらの化合物において４位に置換したハロゲン原子が３位に置換した化合物、さらにこれらの化合物においてジフェニルエーテルの４位に置換した基の少なくとも１つが３位に置換した化合物などが挙げられる。
【００２７】
さらに上記一般式（Ａ）で表されるモノマーとしては、２，２−ビス［４−｛４−（４−クロロベンゾイル）フェノキシ｝フェニル］−１，１，１，３，３，３−ヘキサフルオロプロパン、ビス［４−｛４−（４−クロロベンゾイル）フェノキシ｝フェニル］スルホン、および下記式で表される化合物が挙げられる。
【００２８】
【化３】

【００２９】
上記一般式（Ａ）で表されるモノマーは、例えば以下に示す方法で合成することができる。
まず電子吸引性基で連結されたビスフェノールを対応するビスフェノールのアルカリ金属塩とするために、Ｎ−メチル−２−ピロリドン、Ｎ，Ｎ−ジメチルアセトアミド、スルホラン、ジフェニルスルホン、ジメチルスルホキサイドなどの誘電率の高い極性溶媒中でリチウム、ナトリウム、カリウムなどのアルカリ金属、水素化アルカリ金属、水酸化アルカリ金属、アルカリ金属炭酸塩などを加える。
【００３０】
通常、アルカリ金属はフェノールの水酸基に対し、過剰気味で反応させ、通常、１．１〜２倍当量を使用する。好ましくは、１．２〜１．５倍当量の使用である。この際、ベンゼン、トルエン、キシレン、ヘキサン、シクロヘキサン、オクタン、クロロベンゼン、ジオキサン、テトラヒドロフラン、アニソール、フェネトールなどの水と共沸する溶媒を共存させて、電子吸引性基で活性化されたフッ素、塩素等のハロゲン原子で置換された芳香族ジハライド化合物、例えば、４，４’−ジフルオロベンゾフェノン、４，４’−ジクロロベンゾフェノン、４，４’−クロロフルオロベンゾフェノン、ビス（４−クロロフェニル）スルホン、ビス（４−フルオロフェニル）スルホン、４−フルオロフェニル−４’−クロロフェニルスルホン、ビス（３−ニトロ−４−クロロフェニル）スルホン、２，６−ジクロロベンゾニトリル、２，６−ジフルオロベンゾニトリル、ヘキサフルオロベンゼン、デカフルオロビフェニル、２，５−ジフルオロベンゾフェノン、１，３−ビス（４−クロロベンゾイル）ベンゼンなどを反応させる。反応性から言えば、フッ素化合物が好ましいが、次の芳香族カップリング反応を考慮した場合、末端が塩素原子となるように芳香族求核置換反応を組み立てる必要がある。活性芳香族ジハライドはビスフェノールに対し、２〜４倍モル、好ましくは２．２〜２．８倍モルの使用である。芳香族求核置換反応の前に予め、ビスフェノールのアルカリ金属塩としていてもよい。反応温度は６０℃〜３００℃で、好ましくは８０℃〜２５０℃の範囲である。反応時間は１５分〜１００時間、好ましくは１時間〜２４時間の範囲である。最も好ましい方法としては、下記式で示される活性芳香族ジハライドとして反応性の異なるハロゲン原子を一個づつ有するクロロフルオロ体を用いることであり、フッ素原子が優先してフェノキシドと求核置換反応が起きるので、目的の活性化された末端クロロ体を得るのに好都合である。
【００３１】
【化４】

【００３２】
（式中、Ｘは一般式（Ａ）に関して定義した通りである。）
または特開平２−１５９号公報に記載のように求核置換反応と親電子置換反応を組み合わせ、目的の電子吸引性基、電子供与性基からなる屈曲性化合物の合成方法がある。
具体的には電子吸引性基で活性化された芳香族ビスハライド、例えば、ビス（４−クロロフェニル）スルホンをフェノールとで求核置換反応させてビスフェノキシ置換体とする。次いで、この置換体を例えば、４−クロロ安息香酸クロリドとのフリーデルクラフト反応から目的の化合物を得る。ここで用いる電子吸引性基で活性化された芳香族ビスハライドは上記で例示した化合物が適用できる。フェノール化合物は置換されていてもよいが、耐熱性や屈曲性の観点から、無置換化合物が好ましい。なお、フェノールの置換反応にはアルカリ金属塩とするのが、好ましく、使用可能なアルカリ金属化合物は上記に例示した化合物を使用できる。使用量はフェノール１モルに対し、１．２〜２倍モルである。反応に際し、上述した極性溶媒や水との共沸溶媒を用いることができる。ビスフェノキシ化合物を塩化アルミニウム、三フッ化ホウ素、塩化亜鉛などのルイス酸のフリーデルクラフト反応の活性化剤存在下に、アシル化剤として、クロロ安息香酸クロライドを反応させる。クロロ安息香酸クロライドはビスフェノキシ化合物に対し、２〜４倍モル、好ましくは２．２〜３倍モルの使用である。フリーデルクラフト活性化剤は、アシル化剤のクロロ安息香酸などの活性ハライド化合物１モルに対し、１．１〜２倍当量使用する。反応時間は１５分〜１０時間の範囲で、反応温度は−２０℃から８０℃の範囲である。使用溶媒は、フリーデルクラフト反応に不活性な、クロロベンゼンやニトロベンゼンなどを用いることができる。
【００３３】
また、一般式（Ａ）において、ｎが２以上であるモノマー（Ａ）は、例えば、一般式（Ａ）において電子供与性基Ｙであるエーテル性酸素の供給源となるビスフェノールと、電子吸引性基Ｘである、＞Ｃ＝Ｏ、−ＳＯ_２−、および／または＞Ｃ（ＣＦ_３）_２とを組み合わせた化合物、具体的には２，２−ビス（４−ヒドロキシフェニル）−１，１，１，３，３，３−ヘキサフルオロプロパン、２，２−ビス（４−ヒドロキシフェニル）ケトン、２，２−ビス（４−ヒドロキシフェニル）スルホンなどのビスフェノールのアルカリ金属塩と過剰の４，４−ジクロロベンゾフェノン、ビス（４−クロロフェニル）スルホンなどの活性芳香族ハロゲン化合物との置換反応をＮ−メチル−２−ピロリドン、Ｎ，Ｎ−ジメチルアセトアミド、スルホランなどの極性溶媒存在下で前記単量体の合成手法に順次重合して得られる。
【００３４】
このようなモノマー（Ａ）の例示としては、下記式で表される化合物などを挙げることができる。
【００３５】
【化５】

【００３６】
【化６】

【００３７】
【化７】

【００３８】
上記において、ｎは２以上、好ましくは２〜１００である。
次に一般式（Ｂ−１）〜（Ｂ−４）で表されるモノマーについて説明する。
【００３９】
【化８】

【００４０】
式中、ＲおよびＲ’は互いに同一でも異なっていてもよく、上記一般式（Ａ）中のＲおよびＲ’と同様の基を示す。
Ｒ^９〜Ｒ^１５は互いに同一でも異なっていてもよく、水素原子、フッ素原子およびアルキル基からなる群より選ばれた少なくとも１種の原子または基を示す。
Ｒ^９〜Ｒ^１５が示すアルキル基としては、上記一般式（Ａ）中のＲ^１〜Ｒ^８が示すアルキル基と同様のものが挙げられる。
【００４１】
ｍは０、１または２を示す。
Ｘは上記一般式（Ａ）でＸとして示したものと同様の群から選ばれた２価の電子吸引性基を示す。
Ｙは上記一般式（Ａ）でＹとして示したものと同様の群から選ばれた２価の電子供与性基を示す。
【００４２】
Ｗはフェニル基、ナフチル基および下記式（Ｃ−１）〜（Ｃ−３）で表される基からなる群より選ばれる少なくとも１種の基を示す。
【００４３】
【化９】

【００４４】
式中、Ａは電子供与性基または単結合を示す。電子供与性基としては、上記一般式（Ａ）でＹとして示したものと同様の群から選ばれた２価の電子供与性基が挙げられる。
Ｒ^１６およびＲ^１７は水素原子、アルキル基およびアリール基からなる群より選ばれる原子または基を示す。Ｒ^１６およびＲ^１７が示すアルキル基およびアリール基としては、上記一般式（Ａ）中のＲ^１〜Ｒ^８が示すアルキル基およびアリール基と同様のものが挙げられる。
【００４５】
Ｒ^１８〜Ｒ^２６は互いに同一でも異なっていてもよく、水素原子、フッ素原子およびアルキル基からなる群より選ばれる少なくとも１種の原子または基を示す。
ｑは０または１を示す。
上記一般式（Ｂ−１）で表されるモノマーとしては、下記式で表される化合物が挙げられる。
【００４６】
【化１０】

【００４７】
より具体的には、一般式（Ｂ−１）で表される化合物としては、下記式で表される化合物が挙げられる。
【００４８】
【化１１】

【００４９】
【化１２】

【００５０】
また、上記のような化合物において、塩素原子を臭素原子またはヨウ素原子に置き換えた化合物も例示することができる。
【００５１】
【化１３】

【００５２】
式（Ｂ−２）〜（Ｂ−４）中、ＲおよびＲ’は互いに同一でも異なっていてもよく、上記一般式（Ａ）中のＲおよびＲ’と同様の基を示す。
Ｒ^２７〜Ｒ^３４は互いに同一でも異なっていてもよく、水素原子、フッ素原子、アルキル基、フッ素置換アルキル基、アリール基または下記一般式（Ｄ）で表される基を示す。
【００５３】
【化１４】

【００５４】
式（Ｄ）中、Ｒ^３５〜Ｒ^４３は互いに同一でも異なっていてもよく、水素原子、ハロゲン原子、アルキル基、フッ素置換アルキル基を示す。
Ｒ^２７〜Ｒ^３４、Ｒ^３５〜Ｒ^４３が示すアルキル基、フッ素置換アルキル基としては、Ｒ^１〜Ｒ^８が示すアルキル基、フッ素置換アルキル基と同様の基が挙げられる。またＲ^２７〜Ｒ^３４が示すアリール基としては、Ｒ^１〜Ｒ^８が示すアリール基と同様の基が挙げられる。
【００５５】
Ｘは上記一般式（Ａ）でＸとして示したものと同様の群から選ばれた２価の電子吸引性基を示す。
Ｙは上記一般式（Ａ）でＹとして示したものと同様の群から選ばれた２価の電子供与性基を示す。
上記一般式（Ｂ−２）で表されるモノマーとして具体的には、例えばｐ−ジクロロベンゼン、ｐ−ジメチルスルフォニロキシベンゼン、２，５−ジクロロトルエン、２，５−ジメチルスルフォニロキシベンゼン、２，５−ジクロロ−ｐ−キシレン、２，５−ジクロロベンゾトリフルオライド、１，４−ジクロロ−２，３，５，６−テトラフルオロベンゼン、およびこれらの化合物において塩素原子を臭素原子またはヨウ素原子に置き換えた化合物などが挙げられる。
【００５６】
上記一般式（Ｂ−３）で表されるモノマーとして具体的には、例えば４，４’−ジメチルスルフォニロキシビフェニル、４，４’−ジメチルスルフォニロキシ−３，３’−ジプロペニルビフェニル、４，４’−ジブロモビフェニル、４，４’−ジヨードビフェニル、４，４’−ジメチルスルフォニロキシ−３，３’−ジメチルビフェニル、４，４’−ジメチルスルフォニロキシ−３，３’−ジフルオロビフェニル、４，４’−ジメチルスルフォニロキシ−３，３’５，５’−テトラフルオロビフェニル、４，４’−ジブロモオクタフルオロビフェニル、４，４’−ジメチルスルフォニロキシオクタフルオロビフェニルなどが挙げられる。
【００５７】
上記一般式（Ｂ−４）で表されるモノマーとして具体的には、例えばｍ−ジクロロベンゼン、ｍ−ジメチルスルフォニロキシベンゼン、２，４−ジクロロトルエン、３，５−ジクロロトルエン、２，６−ジクロロトルエン、３，５−ジメチルスルフォニロキシトルエン、２，６−ジメチルスルフォニロキシトルエン、２，４−ジクロロベンゾトリフルオライド、３，５−ジクロロベンゾトリフルオライド、１，３−ジブロモ−２，４，５，６−テトラフルオロベンゼン、およびこれらの化合物において塩素原子を臭素原子またはヨウ素原子に置き換えた化合物などが挙げられる。
【００５８】
ポリアリーレンは上記モノマーを触媒の存在下に反応させることにより得られるが、使用される触媒は、遷移金属化合物を含む触媒系であり、この触媒系としては、▲１▼遷移金属塩および配位子となる化合物（以下、「配位子成分」という。）、または配位子が配位された遷移金属錯体（銅塩を含む）、ならびに▲２▼還元剤を必須成分とし、さらに、重合速度を上げるために、「塩」を添加してもよい。
【００５９】
ここで、遷移金属塩としては、塩化ニッケル、臭化ニッケル、ヨウ化ニッケル、ニッケルアセチルアセトナートなどのニッケル化合物；塩化パラジウム、臭化パラジウム、ヨウ化パラジウムなどのパラジウム化合物；塩化鉄、臭化鉄、ヨウ化鉄などの鉄化合物；塩化コバルト、臭化コバルト、ヨウ化コバルトなどのコバルト化合物などが挙げられる。これらのうち特に、塩化ニッケル、臭化ニッケルなどが好ましい。
【００６０】
また、配位子成分としては、トリフェニルホスフィン、２，２’−ビピリジン、１，５−シクロオクタジエン、１，３−ビス（ジフェニルホスフィノ）プロパンなどが挙げられる。これらのうち、トリフェニルホスフィン、２，２’−ビピリジンが好ましい。上記配位子成分である化合物は、１種単独で、あるいは２種以上を併用することができる。
【００６１】
さらに、配位子が配位された遷移金属錯体としては、例えば、塩化ニッケルビス（トリフェニルホスフィン）、臭化ニッケルビス（トリフェニルホスフィン）、ヨウ化ニッケルビス（トリフェニルホスフィン）、硝酸ニッケルビス（トリフェニルホスフィン）、塩化ニッケル（２，２’−ビピリジン）、臭化ニッケル（２，２’−ビピリジン）、ヨウ化ニッケル（２，２’−ビピリジン）、硝酸ニッケル（２，２’−ビピリジン）、ビス（１，５−シクロオクタジエン）ニッケル、テトラキス（トリフェニルホスフィン）ニッケル、テトラキス（トリフェニルホスファイト）ニッケル、テトラキス（トリフェニルホスフィン）パラジウムなどが挙げられる。これらのうち、塩化ニッケルビス（トリフェニルホスフィン）、塩化ニッケル（２，２’−ビピリジン）が好ましい。
【００６２】
上記触媒系に使用することができる還元剤としては、例えば、鉄、亜鉛、マンガン、アルミニウム、マグネシウム、ナトリウム、カルシウムなどが挙げられる。これらのうち、亜鉛、マグネシウム、マンガンが好ましい。これらの還元剤は、有機酸などの酸に接触させることにより、より活性化して用いることができる。
【００６３】
また、上記触媒系において使用することのできる「塩」としては、フッ化ナトリウム、塩化ナトリウム、臭化ナトリウム、ヨウ化ナトリウム、硫酸ナトリウムなどのナトリウム化合物、フッ化カリウム、塩化カリウム、臭化カリウム、ヨウ化カリウム、硫酸カリウムなどのカリウム化合物；フッ化テトラエチルアンモニウム、塩化テトラエチルアンモニウム、臭化テトラエチルアンモニウム、ヨウ化テトラエチルアンモニウム、硫酸テトラエチルアンモニウムなどのアンモニウム化合物などが挙げられる。これらのうち、臭化ナトリウム、ヨウ化ナトリウム、臭化カリウム、臭化テトラエチルアンモニウム、ヨウ化テトラエチルアンモニウムが好ましい。
【００６４】
各成分の使用割合は、遷移金属塩または遷移金属錯体が、上記モノマーの総計１モルに対し、通常、０．０００１〜１０モル、好ましくは０．０１〜０．５モルである。０．０００１モル未満では、重合反応が十分に進行しないことがあり、一方、１０モルを超えると、分子量が低下することがある。
触媒系において、遷移金属塩および配位子成分を用いる場合、この配位子成分の使用割合は、遷移金属塩１モルに対し、通常、０．１〜１００モル、好ましくは１〜１０モルである。０．１モル未満では、触媒活性が不十分となることがあり、一方、１００モルを超えると、分子量が低下することがある。
【００６５】
また、還元剤の使用割合は、上記モノマーの総計１モルに対し、通常、０．１〜１００モル、好ましくは１〜１０モルである。０．１モル未満では、重合が十分進行しないことがあり、１００モルを超えると、得られる重合体の精製が困難になることがある。
さらに、「塩」を使用する場合、その使用割合は、上記モノマーの総計１モルに対し、通常、０．００１〜１００モル、好ましくは０．０１〜１モルである。０．００１モル未満では、重合速度を上げる効果が不十分であることがあり、１００モルを超えると、得られる重合体の精製が困難となることがある。
【００６６】
使用することのできる重合溶媒としては、例えばテトラヒドロフラン、シクロヘキサノン、ジメチルスルホキシド、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチル−２−ピロリドン、ａ−ブチロラクトン、ａ−ブチロラクタムなどが挙げられる。これらのうち、テトラヒドロフラン、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチル−２−ピロリドンが好ましい。これらの重合溶媒は、十分に乾燥してから用いることが好ましい。
【００６７】
重合溶媒中における上記モノマーの総計の濃度は、通常、１〜９０重量％、好ましくは５〜４０重量％である。
また、重合する際の重合温度は、通常、０〜２００℃、好ましくは５０〜１２０℃である。また、重合時間は、通常、０．５〜１００時間、好ましくは１〜４０時間である。
【００６８】
このようにして上記一般式（Ａ）で表されるモノマー（Ａ）と、上記一般式（Ｂ−１）〜（Ｂ−４）で表されるモノマーから選ばれる少なくとも１種のモノマー（Ｂ）を重合させることにより、ポリアリーレンを含む重合溶液が得られる。本発明のプロトン伝導性フィルムの製造に用いられる、スルホン化ポリアリーレンは、スルホン酸基を有しない上記ポリアリーレンに、スルホン化剤を用い、常法によりスルホン酸基導入することにより得ることができる。
【００６９】
スルホン酸基を導入する方法としては、例えば、上記スルホン酸基を有しないポリアリーレンを、無水硫酸、発煙硫酸、クロルスルホン酸、硫酸、亜硫酸水素ナトリウムなどの公知のスルホン化剤を用いて、公知の条件でスルホン化することができる〔Ｐｏｌｙｍｅｒ　Ｐｒｅｐｒｉｎｔｓ，Ｊａｐａｎ，Ｖｏｌ．４２，Ｎｏ．３，ｐ．７３０（１９９３）；Ｐｏｌｙｍｅｒ　Ｐｒｅｐｒｉｎｔｓ，Ｊａｐａｎ，Ｖｏｌ．４２，Ｎｏ．３，ｐ．７３６（１９９４）；Ｐｏｌｙｍｅｒ　Ｐｒｅｐｒｉｎｔｓ，Ｊａｐａｎ，Ｖｏｌ．４２，Ｎｏ．７，ｐｐ．２４９０〜２４９２（１９９３）〕。
【００７０】
すなわち、このスルホン化の反応条件としては、上記スルホン酸基を有しないポリアリーレンを、無溶剤下、あるいは溶剤存在下で、上記スルホン化剤と反応させる。溶剤としては、例えばｎ−ヘキサンなどの炭化水素溶剤、テトラヒドロフラン、ジオキサンなどのエーテル系溶剤、ジメチルアセトアミド、ジメチルホルムアミド、ジメチルスルホキシドのような非プロトン系極性溶剤のほか、テトラクロロエタン、ジクロロエタン、クロロホルム、塩化メチレンなどのハロゲン化炭化水素などが挙げられる。反応温度は特に制限はないが、通常、−５０〜２００℃、好ましくは−１０〜１００℃である。また、反応時間は、通常、０．５〜１，０００時間、好ましくは１〜２００時間である。
【００７１】
このようにして得られる、スルホン化ポリアリーレン中の、スルホン酸基量は、０．５〜３ミリグラム当量／ｇ、好ましくは０．８〜２．８ミリグラム当量／ｇである。０．５ミリグラム当量／ｇ未満では、プロトン伝導性が上がらず、一方３ミリグラム当量／ｇを超えると、親水性が向上し、水溶性ポリマーとなってしまうか、また水溶性に至らずとも耐久性が低下する。
【００７２】
上記のスルホン酸基量は、モノマー（Ｂ）とモノマー（Ａ）の使用割合、さらにモノマー（Ａ）の種類、組合せを変えることにより、容易に調整することができる。
また、このようにして得られるスルホン化ポリアリーレンのスルホン化前のポリマーの分子量は、ポリスチレン換算重量平均分子量で、１万〜１００万、好ましくは２万〜８０万である。
【００７３】
【実施例】
以下に実施例を挙げ、本発明を具体的に説明するが、本発明は以下の実施例に限定されるものではない。
なお実施例中の残存ＮＭＰ量の測定については、以下のようにして求めた。
（残存ＮＭＰ量）
プロトン伝導性スルホン化ポリマー膜をＤＭＳＯ−ｄ６に溶解し、^１Ｈ−ＮＭＲ（ＤＭＳＯ−ｄ６溶液）１２８回積算測定する。ポリマーのピーク強度とＮＭＰのピーク強度の比から、ポリマー１００重量部当たりのＮＭＰの重量を残存ＮＭＰ量（単位：重量部）とした。
【００７４】
また、実施例においては、スルホン化ポリアリーレンとして、２，５−ジクロロ−４’−（４−フェノキシフェノキシベンゾフェノン）と４，４−ジクロロベンゾフェノンと２，２−ビス（４−ヒドロキシフェニル）１，１，１，３，３，３−ヘキサフルオロプロパンから得られる４−クロロベンゾイル末端のオリゴマー（数平均分子量１１，２００）から得られる共重合体（数平均分子量５０，０００）のスルホン化ポリマー（スルホン酸当量２．０８ミリ当量／ｇ）を用いた。
【００７５】
【実施例１】
ＮＭＰとメタノールからなる混合溶媒（重量比１／１）に、プロトン伝導性スルホン化ポリマーを１５重量％溶解し、ＰＥＴフィルム上に流延して、１２０℃の熱風循環式オーブンにて１時間予備乾燥させることにより厚み４０μｍの膜を得た。Ａ４サイズに切断した膜２０枚を蒸留水１００リットル中に４８時間浸漬し、８０℃の熱風循環式オーブンにて１時間乾燥してプロトン伝導性フィルムを得た。プロトン伝導性フィルム２０枚の残存ＮＭＰ量の平均値は０．５重量部であり、標準偏差は０．１重量部であった。
【００７６】
【実施例２】
蒸留水中への浸漬時間を１時間とした以外は実施例１と同様にしてプロトン伝導性フィルムを得た。水処理膜２０枚の残存ＮＭＰ量の平均値は１．０重量部であり、標準偏差は０．４重量部であった。
【００７７】
【実施例３】
蒸留水中への浸漬時間を０．１時間とした以外は実施例１と同様にしてプロトン伝導性フィルムを得た。水処理膜２０枚の残存ＮＭＰ量の平均値は２．５重量部であり、標準偏差は１．５重量部であった。
【００７８】
【実施例４】
蒸留水中への浸漬時間を０．０５時間とした以外は実施例１と同様にして水処理膜を得た。プロトン伝導性フィルム２０枚の残存ＮＭＰ量の平均値は５．０重量部であり、標準偏差は２．６重量部であった。
【００７９】
【比較例１】
ＮＭＰとメタノールからなる混合溶媒（重量比１／１）に、プロトン伝導性スルホン化ポリマーを１５重量％溶解し、ＰＥＴフィルム上に流延して、１２０℃の熱風循環式オーブンにて１時間乾燥させることにより厚み４０μｍのプロトン伝導性フィルムを得た。上記オーブン中同様の条件で乾燥したプロトン伝導性フィルム２０枚の残存ＮＭＰ量の平均値は１４重量部であり、標準偏差は０．５重量部であった。
【００８０】
【比較例２】
オーブン乾燥時間を７２時間に延長した以外は、比較例１と同様にして膜を得た。上記オーブン中同様の条件で乾燥したプロトン伝導性フィルム２０枚の残存ＮＭＰ量の平均値は１３．５重量部であり、標準偏差は０．３重量部であった。乾燥時間を延長しても残存溶媒量の低減量化は図れなかった。
【００８１】
【比較例３】
オーブン乾燥温度を１５０℃とし、乾燥時間を７２時間とした以外は、比較例１と同様にしてプロトン伝導性フィルムを得た。上記オーブン中同様の条件で乾燥したプロトン伝導性フィルム２０枚の残存ＮＭＰ量の平均値は１３重量部であり、標準偏差は０．３重量部であった。乾燥温度を上げても、残存溶媒量の低減化はできなかった。
【００８２】
以上の結果を下記表１に示す。
【００８３】
【表１】

【００８４】
【発明の効果】
本発明によるとは、流延法にて作成した未乾燥フィルムを、水中に浸漬した後、乾燥することにより、水中に浸漬せずオーブンで乾燥より短時間で残存溶媒量を少なくでき、かつ残存溶媒量のバラツキが小さい膜を得ることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a proton conductive film and a proton conductive film, in which the amount of an organic solvent used in producing the film is small.
[0002]
[Technical Background of the Invention]
As a method for producing a proton conductive film, for example, there is a solution casting method in which a polymer is dissolved in an organic solvent, cast on a substrate to form a film, and then the obtained film is dried. In forming a film by the solution casting method, a polymer having a highly polar ion exchange group such as a proton conductive polymer uses a highly polar aprotic dipolar solvent as an organic solvent to be dissolved. Since the polar solvent has a high boiling point, it cannot be completely removed when drying the film after film formation, and there is a problem that the polar solvent remains in the obtained proton conductive film. When a polar solvent is present in a high concentration in a proton conductive film, the polar solvent functions as a plasticizer, which impairs the thermal properties of the proton conductive film or starts stable power generation when used as a battery electrolyte. It takes too much time, or the solvent is removed due to the thermal change during the power generation process.As a result, shrinkage stress is applied, resulting in residual strain in the film and, depending on the stimulation conditions, cracks in the film and cell deformation. Or other problems may occur.
[0003]
[Problems to be solved by the invention]
The present invention is intended to solve the problems in the prior art as described above, and a method for producing a proton-conductive film having a small residual amount of an organic solvent used in producing a film by a solution casting method. And a proton conductive film.
[0004]
[Means for Solving the Problems]
According to the present invention, the following method for producing a proton conductive film and a proton conductive film are provided, and the above object of the present invention is achieved.
(1) A method in which a film in which a proton-conducting polymer is dissolved in an organic solvent soluble in water is formed by a casting method, and the obtained undried film is immersed in water and then dried. A method for producing a proton conductive film, characterized by:
(2) The method for producing a desolvated proton conductive film according to (1), wherein the proton conductive film is made of a polymer into which sulfonic acid is introduced.
(3) The method for producing a proton conductive film according to (1), wherein the proton conductive film is a sulfonated polyarylene.
(4) A proton conductive film in which the content of the water-soluble organic solvent in the proton conductive film is 1% by weight or less.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the proton conductive film and the method for producing the proton conductive film according to the present invention will be specifically described.
In the present invention, for example, a proton conductive polymer such as a sulfonated polyarylene described below is dissolved in a water-soluble organic solvent to form a solution, which is then cast by casting, cast on a substrate, and formed into a film. The film is manufactured by a casting method. Here, the substrate is not particularly limited as long as it is a substrate used in a usual solution casting method. For example, a substrate made of plastic, metal, or the like is used, and preferably, for example, a polyethylene terephthalate (PET) film or the like is used. This is a substrate made of a thermoplastic resin.
[0006]
Examples of the water-soluble organic solvent that dissolves the proton conductive polymer include N-methyl-2-pyrrolidone, N, N-dimethylformamide, γ-butyrolactone, N, N-dimethylacetamide, dimethylsulfoxide, and dimethylurea. And aprotic polar solvents such as N-methyl-2-pyrrolidone (hereinafter also referred to as "NMP"). The aprotic polar solvent can be used alone or in combination of two or more.
[0007]
In the present invention, a mixture of the aprotic polar solvent and an alcohol can be used as the water-soluble organic solvent in which the proton conductive polymer is dissolved. Examples of the alcohol include methanol, ethanol, propyl alcohol, i-propyl alcohol, sec-butyl alcohol, t-butyl alcohol, and the like. Particularly, methanol is preferable because it has an effect of lowering the solution viscosity in a wide composition range. Alcohols can be used alone or in combination of two or more.
[0008]
When a mixture of an aprotic polar solvent and an alcohol is used as the solvent, the aprotic polar solvent is 95 to 25% by weight, preferably 75 to 25% by weight, and the alcohol is 5 to 75% by weight, preferably 25 to 25% by weight. 75% by weight (however, the total is 100% by weight). When the amount of the alcohol is within the above range, the effect of lowering the solution viscosity is excellent.
[0009]
The concentration of the polymer in the solution in which the proton conductive polymer is dissolved depends on the molecular weight of the proton conductive polymer, but is usually 5 to 40% by weight, preferably 7 to 25% by weight. If the content is less than 5% by weight, it is difficult to form a thick film, and pinholes are easily generated. On the other hand, if it exceeds 40% by weight, the solution viscosity is too high, making it difficult to form a film, and may lack surface smoothness.
[0010]
The solution viscosity is usually from 2,000 to 100,000 mPa · s, preferably from 3,000 to 50,000 mPa · s, depending on the molecular weight of the proton conductive polymer and the polymer concentration. If the viscosity is less than 2,000 mPa · s, the solution may have poor retention during film formation and may flow from the substrate. On the other hand, if it exceeds 100,000 mPa · s, the viscosity may be too high to extrude from the die, and it may be difficult to form a film by the casting method.
[0011]
After forming a film as described above, the obtained undried film is immersed in water. By immersing the undried film in water, the organic solvent in the undried film can be replaced with water, and the amount of residual solvent in the obtained proton conductive film can be reduced.
After film formation, the undried film may be pre-dried before immersing the undried film in water. Predrying is performed by keeping the undried film at a temperature of usually 50 to 150 ° C. for 0.1 to 10 hours.
[0012]
When the undried film is immersed in water, a batch method in which the sheet is immersed in water may be used, or a laminated film in a state of being formed on a substrate film (for example, PET) which is usually obtained may be used in water. It can also be applied by a continuous method of immersing in and winding up. In the case of the batch method, a method such as placing the processed film in a frame is advantageous because wrinkling on the surface of the processed film is suppressed.
[0013]
When the wet film is immersed in water, the contact ratio of water to 10 parts by weight or more, preferably 30 parts by weight or more to 1 part by weight of the wet film is good. In order to minimize the amount of residual solvent in the obtained proton conductive film, it is preferable to maintain as large a contact ratio as possible. It is also effective to constantly maintain the organic solvent concentration in the water at a certain concentration or less by changing or overflowing the water used for immersion, which is also effective in reducing the amount of residual solvent in the obtained proton conductive film. It is. In order to suppress the in-plane distribution of the amount of the organic solvent remaining in the proton conductive film, it is effective to homogenize the concentration of the organic solvent in water by stirring or the like.
[0014]
The temperature of water when immersing the wet film in water is preferably in the range of 5 to 80C. The higher the temperature, the faster the substitution rate between the organic solvent and water is increased, but the greater the water absorption of the film is, the more the surface state of the proton conductive film obtained after drying may be roughened. Usually, a temperature range of 10 to 60 ° C. is advantageous from the viewpoint of replacement speed and ease of handling.
[0015]
The immersion time is usually in the range of 10 minutes to 240 hours, depending on the initial amount of the remaining solvent, the contact ratio, and the treatment temperature. Preferably it is in the range of 30 minutes to 100 hours.
When the undried film is immersed in water and dried as described above, a proton conductive film in which the residual amount of the organic solvent that can be dissolved in water in which the proton conductive polymer is dissolved is reduced is obtained. The residual amount of the organic solvent that can be dissolved in water in which the proton conductive polymer of the proton conductive film obtained by the above is dissolved is usually 5% by weight or less. Also, depending on the immersion conditions, it is 1% by weight or less. As such immersion conditions, for example, the contact ratio between the undried film and water is such that water is at least 50 parts by weight with respect to 1 part by weight of the undried film; There is a method in which the time is set to 10 minutes to 10 hours.
[0016]
After immersing the undried film in water as described above, the film is dried at 30-100 ° C., preferably 50-80 ° C., for 10-180 minutes, preferably 15-60 minutes, and then at 50-150 ° C. The proton conductive film can be obtained by vacuum drying under normal pressure or under a reduced pressure of 500 mmHg to 0.1 mmHg for 0.5 to 24 hours.
[0017]
The dry thickness of the proton conductive film obtained by the method of the present invention is usually 10 to 100 μm, preferably 20 to 80 μm.
(Sulfonated polyarylene)
The sulfonated polyarylene used in the present invention includes a monomer (A) represented by the following general formula (A) and at least one monomer selected from the following general formulas (B-1) to (B-4) (B) and a sulfonated polyarylene obtained by sulfonating a polymer obtained by reacting with (B).
[0018]
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[0019]
In the formula (A), R to R ′ may be the same or different from each other, and include a halogen atom excluding a fluorine atom or —OSO ₂ Z represents a group represented by Z (here, Z represents an alkyl group, a fluorine-substituted alkyl group or an aryl group).
Examples of the alkyl group represented by Z include a methyl group and an ethyl group, examples of the fluorine-substituted alkyl group include a trifluoromethyl group, and examples of the aryl group include a phenyl group and a p-tolyl group.
[0020]
R ¹ ~ R ⁸ May be the same or different, and represent at least one atom or group selected from the group consisting of a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an allyl group and an aryl group.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, and a hexyl group, and a methyl group and an ethyl group are preferable.
[0021]
Examples of the fluorine-substituted alkyl group include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group and the like, and a trifluoromethyl group, a pentafluoroethyl group Are preferred.
Examples of the allyl group include a propenyl group,
Examples of the aryl group include a phenyl group and a pentafluorophenyl group.
[0022]
X represents a divalent electron-withdrawing group. Examples of the electron-withdrawing group include -CO-, -CONH-, and-(CF ₂ ) _p -(Where p is an integer of 1 to 10), -C (CF ₃ ) ₂ -, -COO-, -SO-, -SO ₂ -And the like.
Note that the electron-withdrawing group refers to a group having a value of 0.06 or more when the Hammett substituent constant is m-position of the phenyl group and 0.01 or more when it is p-position.
[0023]
Y represents a divalent electron donating group, and examples of the electron donating group include —O—, —S—, —CH ＝ CH—, —C≡C— and
[0024]
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[0025]
And the like.
n is 0 or a positive integer, and the upper limit is usually 100, preferably 80.
Specific examples of the monomer represented by the general formula (A) include, for example, 4,4′-dichlorobenzophenone, 4,4′-dichlorobenzanilide, bis (chlorophenyl) difluoromethane, 2,2-bis (4- (Chlorophenyl) hexafluoropropane, 4-chlorophenyl 4-chlorobenzoate, bis (4-chlorophenyl) sulfoxide, bis (4-chlorophenyl) sulfone, a compound in which a chlorine atom is replaced with a bromine atom or an iodine atom in these compounds, Examples of these compounds include compounds in which a halogen atom substituted in the 4-position is substituted in the 3-position.
[0026]
Specific examples of the monomer represented by the general formula (A) include, for example, 4,4′-bis (4-chlorobenzoyl) diphenyl ether, 4,4′-bis (4-chlorobenzoylamino) diphenyl ether, 4'-bis (4-chlorophenylsulfonyl) diphenyl ether, 4,4'-bis (4-chlorophenyl) diphenyl ether dicarboxylate, 4,4'-bis [(4-chlorophenyl) -1,1,1,3,3 , 3-Hexafluoropropyl] diphenyl ether, 4,4'-bis [(4-chlorophenyl) -1,1,1,3,3,3-hexafluoropropyl] diphenyl ether, 4,4'-bis [(4- Chlorophenyl) tetrafluoroethyl] diphenyl ether, and in these compounds, chlorine atom is bromine atom or iodine atom And compounds in which a halogen atom substituted in the 4-position is substituted in the 3-position, and compounds in which at least one of the groups substituted in the 4-position of diphenyl ether is substituted in the 3-position. No.
[0027]
Further, as the monomer represented by the general formula (A), 2,2-bis [4- {4- (4-chlorobenzoyl) phenoxy} phenyl] -1,1,1,3,3,3-hexa Examples thereof include fluoropropane, bis [4- {4- (4-chlorobenzoyl) phenoxy} phenyl] sulfone, and a compound represented by the following formula.
[0028]
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[0029]
The monomer represented by the general formula (A) can be synthesized, for example, by the following method.
First, in order to convert a bisphenol linked by an electron-withdrawing group into a corresponding alkali metal salt of bisphenol, a dielectric material such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, sulfolane, diphenylsulfone, and dimethylsulfoxide is used. An alkali metal such as lithium, sodium and potassium, an alkali metal hydride, an alkali metal hydroxide, an alkali metal carbonate and the like are added in a highly polar solvent.
[0030]
Usually, the alkali metal is reacted with the hydroxyl group of phenol in an excessive amount, and usually, 1.1 to 2 equivalents are used. Preferably, 1.2 to 1.5 equivalents are used. At this time, a solvent azeotropic with water such as benzene, toluene, xylene, hexane, cyclohexane, octane, chlorobenzene, dioxane, tetrahydrofuran, anisole, and phenetole coexist to form fluorine, chlorine, and the like activated by the electron-withdrawing group. Aromatic dihalide compounds substituted with a halogen atom such as 4,4'-difluorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-chlorofluorobenzophenone, bis (4-chlorophenyl) sulfone, bis (4 -Fluorophenyl) sulfone, 4-fluorophenyl-4'-chlorophenylsulfone, bis (3-nitro-4-chlorophenyl) sulfone, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile, hexafluorobenzene, deca Fluorobife , 2,5-difluorobenzophenone, 1,3-bis (4-chlorobenzoyl) benzene and the like. In terms of reactivity, a fluorine compound is preferable, but in consideration of the following aromatic coupling reaction, it is necessary to assemble an aromatic nucleophilic substitution reaction so that the terminal is a chlorine atom. The active aromatic dihalide is used in an amount of 2 to 4 times, preferably 2.2 to 2.8 times, the mole of bisphenol. Before the aromatic nucleophilic substitution reaction, an alkali metal salt of bisphenol may be used in advance. The reaction temperature is between 60C and 300C, preferably between 80C and 250C. Reaction times range from 15 minutes to 100 hours, preferably from 1 hour to 24 hours. The most preferable method is to use a chlorofluoro compound having one halogen atom having different reactivity one by one as an active aromatic dihalide represented by the following formula, since a fluorine atom preferentially causes a nucleophilic substitution reaction with phenoxide. It is convenient for obtaining the desired activated terminal chloro form.
[0031]
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[0032]
(In the formula, X is as defined for the general formula (A).)
Alternatively, as described in JP-A-2-159, there is a method of combining a nucleophilic substitution reaction and an electrophilic substitution reaction to synthesize a flexible compound comprising an intended electron-withdrawing group and an electron-donating group.
Specifically, an aromatic bishalide activated by an electron-withdrawing group, for example, bis (4-chlorophenyl) sulfone is subjected to a nucleophilic substitution reaction with phenol to obtain a bisphenoxy-substituted product. Then, the desired compound is obtained from this substituted product by a Friedel-Crafts reaction with, for example, 4-chlorobenzoic acid chloride. The compounds exemplified above can be applied to the aromatic bishalide activated by the electron-withdrawing group used here. The phenol compound may be substituted, but an unsubstituted compound is preferred from the viewpoint of heat resistance and flexibility. It is preferable to use an alkali metal salt for the phenol substitution reaction. As the usable alkali metal compound, the compounds exemplified above can be used. The amount used is 1.2 to 2 moles per 1 mole of phenol. At the time of the reaction, the above-mentioned polar solvent or the azeotropic solvent with water can be used. The bisphenoxy compound is reacted with chlorobenzoic acid chloride as an acylating agent in the presence of an activator for the Friedel-Crafts reaction of a Lewis acid such as aluminum chloride, boron trifluoride, zinc chloride or the like. Chlorobenzoic acid chloride is used in an amount of 2 to 4 times, preferably 2.2 to 3 times the mole of the bisphenoxy compound. The Friedel-Crafts activator is used in an amount of 1.1 to 2 equivalents per mol of an active halide compound such as chlorobenzoic acid as an acylating agent. The reaction time ranges from 15 minutes to 10 hours, and the reaction temperature ranges from -20C to 80C. As a solvent to be used, chlorobenzene, nitrobenzene, or the like, which is inert to the Friedel-Crafts reaction, can be used.
[0033]
Further, in the general formula (A), the monomer (A) in which n is 2 or more is, for example, bisphenol which is a supply source of etheric oxygen which is the electron donating group Y in the general formula (A); A group X,> C = O, -SO ₂ And / or> C (CF ₃ ) ₂ And specifically 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane and 2,2-bis (4-hydroxyphenyl) ketone Reaction of an alkali metal salt of bisphenol such as 2,2, bis (4-hydroxyphenyl) sulfone with an excess of an active aromatic halogen compound such as 4,4-dichlorobenzophenone or bis (4-chlorophenyl) sulfone by N -Methyl-2-pyrrolidone, N, N-dimethylacetamide, sulfolane, and the like, and sequentially polymerized in the presence of a polar solvent such as a monomer synthesis method.
[0034]
Examples of such a monomer (A) include a compound represented by the following formula.
[0035]
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[0036]
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[0037]
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[0038]
In the above, n is 2 or more, preferably 2 to 100.
Next, the monomers represented by formulas (B-1) to (B-4) will be described.
[0039]
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[0040]
In the formula, R and R ′ may be the same or different from each other, and represent the same groups as R and R ′ in the general formula (A).
R ⁹ ~ R ^Fifteen And may be the same or different and represent at least one atom or group selected from the group consisting of a hydrogen atom, a fluorine atom and an alkyl group.
R ⁹ ~ R ^Fifteen Is an alkyl group represented by R in the general formula (A) ¹ ~ R ⁸ And the same as the alkyl group represented by.
[0041]
m represents 0, 1 or 2.
X represents a divalent electron-withdrawing group selected from the same group as that shown as X in the general formula (A).
Y represents a divalent electron-donating group selected from the same group as that represented as Y in the general formula (A).
[0042]
W represents at least one group selected from the group consisting of a phenyl group, a naphthyl group and groups represented by the following formulas (C-1) to (C-3).
[0043]
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[0044]
In the formula, A represents an electron donating group or a single bond. Examples of the electron donating group include divalent electron donating groups selected from the same groups as those represented by Y in the above general formula (A).
R ¹⁶ And R ¹⁷ Represents an atom or a group selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group. R ¹⁶ And R ¹⁷ As the alkyl group and the aryl group represented by ¹ ~ R ⁸ And the same as the alkyl group and the aryl group.
[0045]
R ¹⁸ ~ R ²⁶ May be the same or different, and represent at least one atom or group selected from the group consisting of a hydrogen atom, a fluorine atom and an alkyl group.
q represents 0 or 1.
Examples of the monomer represented by the general formula (B-1) include a compound represented by the following formula.
[0046]
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[0047]
More specifically, the compound represented by the general formula (B-1) includes a compound represented by the following formula.
[0048]
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[0049]
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[0050]
In addition, compounds in which a chlorine atom is replaced with a bromine atom or an iodine atom in the above compounds can also be exemplified.
[0051]
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[0052]
In the formulas (B-2) to (B-4), R and R ′ may be the same or different, and represent the same groups as R and R ′ in the general formula (A).
R ²⁷ ~ R ³⁴ May be the same or different, and represent a hydrogen atom, a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, an aryl group or a group represented by the following formula (D).
[0053]
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[0054]
In the formula (D), R ³⁵ ~ R ⁴³ May be the same or different, and represent a hydrogen atom, a halogen atom, an alkyl group, or a fluorine-substituted alkyl group.
R ²⁷ ~ R ³⁴ , R ³⁵ ~ R ⁴³ As the alkyl group and fluorine-substituted alkyl group represented by ¹ ~ R ⁸ And the same groups as the alkyl group and the fluorine-substituted alkyl group. Also R ²⁷ ~ R ³⁴ The aryl group represented by ¹ ~ R ⁸ And the same groups as the aryl groups represented by.
[0055]
X represents a divalent electron-withdrawing group selected from the same group as that shown as X in the general formula (A).
Y represents a divalent electron-donating group selected from the same group as that represented as Y in the general formula (A).
Specific examples of the monomer represented by the general formula (B-2) include, for example, p-dichlorobenzene, p-dimethylsulfonyloxybenzene, 2,5-dichlorotoluene, 2,5-dimethylsulfonyloxybenzene, 2,5-dichloro-p-xylene, 2,5-dichlorobenzotrifluoride, 1,4-dichloro-2,3,5,6-tetrafluorobenzene, and a chlorine or bromine atom or an iodine atom in these compounds And the like.
[0056]
Specific examples of the monomer represented by the general formula (B-3) include, for example, 4,4′-dimethylsulfonyloxybiphenyl, 4,4′-dimethylsulfonyloxy-3,3′-dipropenylbiphenyl, 4,4'-dibromobiphenyl, 4,4'-diiodobiphenyl, 4,4'-dimethylsulfonyloxy-3,3'-dimethylbiphenyl, 4,4'-dimethylsulfonyloxy-3,3'- Difluorobiphenyl, 4,4'-dimethylsulfonyloxy-3,3'5,5'-tetrafluorobiphenyl, 4,4'-dibromooctafluorobiphenyl, 4,4'-dimethylsulfonyloxyoctafluorobiphenyl and the like No.
[0057]
Specific examples of the monomer represented by the general formula (B-4) include, for example, m-dichlorobenzene, m-dimethylsulfonyloxybenzene, 2,4-dichlorotoluene, 3,5-dichlorotoluene, 2,6 -Dichlorotoluene, 3,5-dimethylsulfonyloxytoluene, 2,6-dimethylsulfonyloxytoluene, 2,4-dichlorobenzotrifluoride, 3,5-dichlorobenzotrifluoride, 1,3-dibromo-2, Examples thereof include 4,5,6-tetrafluorobenzene, and compounds in which a chlorine atom is replaced with a bromine atom or an iodine atom in these compounds.
[0058]
Polyarylene can be obtained by reacting the above monomer in the presence of a catalyst. The catalyst used is a catalyst system containing a transition metal compound. The catalyst system includes (1) a transition metal salt and a coordination catalyst. A ligand compound (hereinafter, referred to as a “ligand component”), a transition metal complex to which a ligand is coordinated (including a copper salt), and (2) a reducing agent as essential components. "Salts" may be added to increase speed.
[0059]
Here, as the transition metal salt, nickel compounds such as nickel chloride, nickel bromide, nickel iodide, and nickel acetylacetonate; palladium compounds such as palladium chloride, palladium bromide, and palladium iodide; iron chloride, iron bromide And iron compounds such as iron iodide; and cobalt compounds such as cobalt chloride, cobalt bromide and cobalt iodide. Of these, nickel chloride and nickel bromide are particularly preferred.
[0060]
Examples of the ligand component include triphenylphosphine, 2,2′-bipyridine, 1,5-cyclooctadiene, and 1,3-bis (diphenylphosphino) propane. Of these, triphenylphosphine and 2,2′-bipyridine are preferred. The compounds as the ligand components can be used alone or in combination of two or more.
[0061]
Further, examples of the transition metal complex to which the ligand is coordinated include nickel bis (triphenylphosphine) chloride, nickel bis (triphenylphosphine) bromide, nickel bis (triphenylphosphine) iodide, and nickel bis (nitrate) nitrate. (Triphenylphosphine), nickel chloride (2,2'-bipyridine), nickel bromide (2,2'-bipyridine), nickel iodide (2,2'-bipyridine), nickel nitrate (2,2'-bipyridine) ), Bis (1,5-cyclooctadiene) nickel, tetrakis (triphenylphosphine) nickel, tetrakis (triphenylphosphite) nickel, tetrakis (triphenylphosphine) palladium and the like. Of these, nickel chloride bis (triphenylphosphine) and nickel chloride (2,2′-bipyridine) are preferred.
[0062]
Examples of the reducing agent that can be used in the above catalyst system include iron, zinc, manganese, aluminum, magnesium, sodium, and calcium. Of these, zinc, magnesium and manganese are preferred. These reducing agents can be used more activated by contact with an acid such as an organic acid.
[0063]
Examples of the “salt” that can be used in the above catalyst system include sodium compounds such as sodium fluoride, sodium chloride, sodium bromide, sodium iodide, and sodium sulfate, potassium fluoride, potassium chloride, potassium bromide, Potassium compounds such as potassium iodide and potassium sulfate; and ammonium compounds such as tetraethylammonium fluoride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, and tetraethylammonium sulfate. Of these, sodium bromide, sodium iodide, potassium bromide, tetraethylammonium bromide, and tetraethylammonium iodide are preferred.
[0064]
The usage ratio of each component is such that the transition metal salt or the transition metal complex is usually 0.0001 to 10 mol, preferably 0.01 to 0.5 mol, per 1 mol of the total of the above monomers. If the amount is less than 0.0001 mol, the polymerization reaction may not proceed sufficiently, while if it exceeds 10 mol, the molecular weight may decrease.
When a transition metal salt and a ligand component are used in the catalyst system, the usage ratio of the ligand component is usually 0.1 to 100 mol, preferably 1 to 10 mol, per 1 mol of the transition metal salt. is there. If the amount is less than 0.1 mol, the catalytic activity may be insufficient, while if it exceeds 100 mol, the molecular weight may decrease.
[0065]
The reducing agent is used in an amount of usually 0.1 to 100 mol, preferably 1 to 10 mol, per 1 mol of the total amount of the monomers. If the amount is less than 0.1 mol, the polymerization may not proceed sufficiently. If the amount exceeds 100 mol, purification of the obtained polymer may be difficult.
Further, when a "salt" is used, the proportion of the salt is usually 0.001 to 100 mol, preferably 0.01 to 1 mol, per 1 mol of the total of the above monomers. If the amount is less than 0.001 mol, the effect of increasing the polymerization rate may be insufficient. If the amount exceeds 100 mol, purification of the obtained polymer may be difficult.
[0066]
Examples of the polymerization solvent that can be used include tetrahydrofuran, cyclohexanone, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, a-butyrolactone, and a-butyrolactam. Can be Of these, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferred. These polymerization solvents are preferably used after being sufficiently dried.
[0067]
The total concentration of the above monomers in the polymerization solvent is usually 1 to 90% by weight, preferably 5 to 40% by weight.
Further, the polymerization temperature at the time of polymerization is usually 0 to 200 ° C, preferably 50 to 120 ° C. Further, the polymerization time is usually 0.5 to 100 hours, preferably 1 to 40 hours.
[0068]
Thus, the monomer (A) represented by the general formula (A) and at least one monomer (B) selected from the monomers represented by the general formulas (B-1) to (B-4) Is polymerized to obtain a polymerization solution containing polyarylene. The sulfonated polyarylene used in the production of the proton conductive film of the present invention can be obtained by using a sulfonating agent and introducing a sulfonic acid group by a conventional method to the above polyarylene having no sulfonic acid group. .
[0069]
As a method for introducing a sulfonic acid group, for example, a polyarylene having no sulfonic acid group can be obtained by using a known sulfonating agent such as sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid, sulfuric acid, and sodium hydrogen sulfite. [Polymer Preprints, Japan, Vol. 42, no. 3, p. 730 (1993); Polymer Preprints, Japan, Vol. 42, no. 3, p. 736 (1994); Polymer Preprints, Japan, Vol. 42, no. 7, pp. 2490-2492 (1993)].
[0070]
That is, as the reaction conditions for this sulfonation, the above-mentioned polyarylene having no sulfonic acid group is reacted with the above-mentioned sulfonating agent in the absence or presence of a solvent. Examples of the solvent include hydrocarbon solvents such as n-hexane, ether solvents such as tetrahydrofuran and dioxane, aprotic polar solvents such as dimethylacetamide, dimethylformamide, and dimethylsulfoxide, as well as tetrachloroethane, dichloroethane, chloroform, and chloride. And halogenated hydrocarbons such as methylene. The reaction temperature is not particularly limited, but is generally -50 to 200C, preferably -10 to 100C. The reaction time is usually 0.5 to 1,000 hours, preferably 1 to 200 hours.
[0071]
The amount of sulfonic acid groups in the sulfonated polyarylene thus obtained is 0.5 to 3 milligram equivalents / g, preferably 0.8 to 2.8 milligram equivalents / g. If it is less than 0.5 milligram equivalent / g, proton conductivity does not increase, while if it exceeds 3 milligram equivalent / g, hydrophilicity is improved and it becomes a water-soluble polymer, or it is durable even if it does not become water-soluble. Is reduced.
[0072]
The amount of the sulfonic acid group can be easily adjusted by changing the usage ratio of the monomer (B) and the monomer (A), and further changing the type and combination of the monomer (A).
The molecular weight of the polymer before sulfonation of the sulfonated polyarylene thus obtained is 10,000 to 1,000,000, preferably 20,000 to 800,000 in terms of polystyrene equivalent weight average molecular weight.
[0073]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to the following Examples.
In addition, about the measurement of the residual NMP amount in an Example, it calculated | required as follows.
(Remaining NMP amount)
Dissolving the proton conductive sulfonated polymer membrane in DMSO-d6, ¹ H-NMR (DMSO-d6 solution) is integrated and measured 128 times. From the ratio of the peak intensity of the polymer to the peak intensity of NMP, the weight of NMP per 100 parts by weight of the polymer was defined as the residual NMP amount (unit: parts by weight).
[0074]
In Examples, 2,5-dichloro-4 ′-(4-phenoxyphenoxybenzophenone), 4,4-dichlorobenzophenone and 2,2-bis (4-hydroxyphenyl) 1,2 are used as sulfonated polyarylene. A sulfonated polymer of a copolymer (number average molecular weight 50,000) obtained from a 4-chlorobenzoyl terminal oligomer (number average molecular weight 11,200) obtained from 1,1,3,3,3-hexafluoropropane ( A sulfonic acid equivalent of 2.08 meq / g) was used.
[0075]
Embodiment 1
15% by weight of a proton-conductive sulfonated polymer was dissolved in a mixed solvent of NMP and methanol (weight ratio 1/1), cast on a PET film, and preliminarily kept in a hot-air circulation oven at 120 ° C for 1 hour. By drying, a film having a thickness of 40 μm was obtained. Twenty membranes cut to A4 size were immersed in 100 liters of distilled water for 48 hours and dried in a hot air circulation oven at 80 ° C. for 1 hour to obtain a proton conductive film. The average value of the residual NMP amount of the 20 proton conductive films was 0.5 part by weight, and the standard deviation was 0.1 part by weight.
[0076]
Embodiment 2
A proton conductive film was obtained in the same manner as in Example 1 except that the immersion time in distilled water was changed to 1 hour. The average value of the residual NMP amount of the 20 water-treated films was 1.0 part by weight, and the standard deviation was 0.4 part by weight.
[0077]
Embodiment 3
A proton conductive film was obtained in the same manner as in Example 1, except that the immersion time in distilled water was changed to 0.1 hour. The average value of the residual NMP amount of the 20 water-treated films was 2.5 parts by weight, and the standard deviation was 1.5 parts by weight.
[0078]
Embodiment 4
A water-treated film was obtained in the same manner as in Example 1, except that the immersion time in distilled water was 0.05 hours. The average value of the residual NMP amount of the 20 proton conductive films was 5.0 parts by weight, and the standard deviation was 2.6 parts by weight.
[0079]
[Comparative Example 1]
15% by weight of a proton conductive sulfonated polymer is dissolved in a mixed solvent of NMP and methanol (weight ratio 1/1), cast on a PET film, and dried in a hot air circulation oven at 120 ° C. for 1 hour. By doing so, a proton conductive film having a thickness of 40 μm was obtained. The average value of the residual NMP amount of 20 pieces of the proton conductive films dried under the same conditions in the oven was 14 parts by weight, and the standard deviation was 0.5 parts by weight.
[0080]
[Comparative Example 2]
A film was obtained in the same manner as in Comparative Example 1, except that the oven drying time was extended to 72 hours. The average value of the residual NMP amount of 20 pieces of the proton conductive films dried in the oven under the same conditions was 13.5 parts by weight, and the standard deviation was 0.3 parts by weight. Even if the drying time was extended, the amount of the remaining solvent could not be reduced.
[0081]
[Comparative Example 3]
A proton conductive film was obtained in the same manner as in Comparative Example 1, except that the oven drying temperature was 150 ° C and the drying time was 72 hours. The average value of the residual NMP amount of 20 proton conductive films dried under the same conditions in the above oven was 13 parts by weight, and the standard deviation was 0.3 parts by weight. Even if the drying temperature was increased, the amount of the residual solvent could not be reduced.
[0082]
The above results are shown in Table 1 below.
[0083]
[Table 1]

[0084]
【The invention's effect】
According to the present invention, the undried film prepared by the casting method is immersed in water and then dried, so that the amount of residual solvent can be reduced in a shorter time than drying in an oven without immersion in water, and A film having a small variation in the amount of the solvent can be obtained.

Claims (4)

It is characterized by forming a film by a casting method using a solution in which a proton conductive polymer is dissolved in a water-soluble organic solvent, dipping the obtained undried film in water, and then drying the film. A method for producing a proton conductive film. The method according to claim 1, wherein the proton conductive polymer is a polymer into which sulfonic acid is introduced. The method for producing a proton conductive film according to claim 1, wherein the proton conductive film is a sulfonated polyarylene. A proton conductive film in which the content of an organic solvent soluble in water in the proton conductive film is 1% by weight or less.