JP4517272B2 - Photocrosslinkable polymer solid electrolyte, cross-linked polymer solid electrolyte membrane and method for producing the same - Google Patents

Description

（式中、Ｒは炭素数１〜１０の脂肪族炭化水素基を、ｎは１〜４の整数を表す。）
（２）不活性ガスが、窒素又はアルゴンであることを特徴とする（１）に記載の架橋高分子固体電解質の製造方法、
【００１１】
（３）分子中に、スルホン酸基又はホスホン酸基からなる群より選ばれる１種以上のイオン性基又はその塩と、下記一般式（１）及び（２）で表される基からなる光架橋性基とをそれぞれ１個以上有しており、ポリマー主鎖がポリエーテルスルホン又はポリエーテルケトンである高分子固体電解質膜及びその前駆体を光照射して架橋高分子固体電解質膜を得る工程において、光照射を不活性ガス中で行うことを特徴とする架橋高分子固体電解質膜の製造方法、
【化２】

（式中、Ｒは炭素数１〜１０の脂肪族炭化水素基を、ｎは１〜４の整数を表す。）
（４）不活性ガスが、窒素又はアルゴンであることを特徴とする（３）に記載の架橋高分子固体電解質膜の製造方法。
（５）膜を治具に固定した状態で光照射することを特徴とする（３）又は（４）に記載の架橋高分子固体電解質膜の製造方法。
（６）（１）又は（２）に記載の方法で製造された架橋高分子固体電解質。
（７）（３）〜（５）に記載の方法で製造された架橋高分子固体電解質膜。
（８）（６）に記載の高分子固体電解質を用いた燃料電池。
（９）（７）に記載の高分子固体電解質膜を用いた燃料電池。
【００１２】
【発明の実施の形態】
以下、本発明に関して詳細に説明する。本発明における光架橋性高分子固体電解質は、ポリマー分子中に少なくとも１個以上の光架橋性基及びイオン性基を有していることが必要である。ポリマーの数平均分子量は１，０００〜１，０００，０００の間であることが好ましく、５，０００〜５００，０００の間であることが物性と加工性のバランスが取れるため好ましい。
【００１３】
イオン性基はスルホン酸基及びホスホン酸基からなる群より選ばれる１種以上のイオン性基及びその塩である。
スルホン酸基はイオン伝導性が高く、ホスホン酸基は高温でもイオン伝導性を示すため、それぞれ好ましい。ポリマー中のイオン性基の量は、０．１〜５．０ｍｍｏｌ／ｇであることが好ましく、１．０〜３．０ｍｍｏｌ／ｇであることがより好ましい。ポリマー中には、イオン性基を有するモノマーの共重合やポリマーのスルホン化反応によってイオン性基を導入することができる。イオン性基を有するモノマーとしては、下記に示すような化合物が挙げられる。
【００１４】
【化３】

また、無水硫酸、無水硫酸の錯体、発煙硫酸、濃硫酸、クロロスルホン酸などのスルホン化剤を用いてポリマーにスルホン酸基を導入することもできる。ポリマーをスルホン化剤に対して不活性な溶媒に溶解した状態でスルホン化剤を反応させる方法や、ポリマーを適当な溶媒で膨潤させた状態でスルホン化剤を反応させる方法、ポリマーを直接スルホン化剤と反応させる方法、などの方法によってスルホン化反応を行なうことができる。スルホン化剤はそのまま用いてもよいし、適当な溶媒に溶解、分散した状態で用いることもできる。反応温度は−１００〜１００℃の間で行なうことができる。
【００１５】
光架橋性基としては、ベンゾフェノン基、α−ジケトン基、アシロイン基、アシロインエーテル基、ベンジルアルキルケタール基、アセトフェノン基、多核キノン類、チオキサントン基、アシルフォスフィン基、エチレン性不飽和基などを挙げることができる。中でもベンゾフェノン機などの光によりラジカルを発生することのできる基と、メチル基やエチル基などの炭化水素基を有する芳香族基などの、ラジカルと反応することのできる基との組み合わせが好ましく、例として下記のような基を挙げることができる。
【００１６】
【化４】

これらの基は、ポリマー中の主鎖、側鎖、、末端基として存在することができる。ポリマー中の光架橋性基の量は、1〜５，０００ｍｍｏｌ／ｋｇであることが好ましく、５〜５，０００ｍｍｏｌ／ｋｇであることがさらに好ましい。このような基は、共重合モノマーや末端停止剤としてポリマー中に導入することができる。またエチレン性不飽和基を用いる場合には、ベンゾフェノン類、α−ジケトン類、アシロイン類、アシロインエーテル類、ベンジルアルキルケタール類、アセトフェノン類、多核キノン類、チオキサントン類、アシルフォスフィン類などの光重合開始剤を加えておくことが好ましい。
【００１７】
ポリマーの主鎖は、ポリエーテルスルホン又はポリエーテルケトンを用いることができる。耐久性に優れ、合成が容易である。
【００１８】
ポリエーテルスルホンやポリエーテルケトンは、電子吸引性基を有する芳香族ジハロゲン化合物と、ビスフェノール化合物を縮合することで得られる。縮合反応は公知の方法で行なうことができる。例えば有機溶媒中で塩基の存在下加熱することで縮合できる。有機溶媒としては、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチル−２−ピロリドン、Ｎ，Ｎ−ジメチルホルムアミド、スルホラン、ジメチルスルホキシドなどの非プロトン性極性溶媒を挙げることができる。中でもＮ−メチル−２−ピロリドンが好ましい。塩基としては、炭酸カリウム、炭酸ナトリウム、水酸化カリウム、水酸化ナトリウムなどが挙げられる。中でも炭酸カリウムが好ましい。ビスフェノール化合物と塩基との反応で生成する水は、トルエンやベンゼンとの共沸で除くことができる。共沸脱水は１００〜１５０℃で行なうことが好ましい。脱水が完了後、縮合反応を行なうことができる。縮合反応は１２０〜３００℃で行なうことができる。反応は窒素、アルゴンなど不活性ガス雰囲気下で行なうことが好ましい。反応終了後、溶液を水、アセトンなどポリマーが不溶の溶媒に投入することで再沈させることができる。再沈したポリマーは、公知の方法で精製することができる。
【００１９】
芳香族ジハロゲン化合物の例としては下記の化合物を挙げることができる。
【化５】

ポリマーにイオン性基を導入する目的で下記の化合物も使用することができる。
【００２０】
【化６】

【００２１】
ビスフェノール化合物の例としては下記の化合物を挙げることができる。
【００２２】
【化７】

【００２３】
ポリマーにラジカル発生基を導入するためのモノマーとしては下記のような化合物を挙げることができる。
【化８】

【００２４】
ポリマーにラジカルと反応する基を導入するためのモノマーは下記のような化合物を挙げることができる。
【化９】

【００２５】
ラジカル発生基とラジカル反応性基は、同一のポリマーにあっても、別々のポリマーにあってもよい。それぞれの基を有する二種以上のポリマーを混合してもよいし、二つの基を有するポリマーを用いてもよい。二種以上のポリマーを用いる場合、イオン性基はいずれのポリマーにあってもよい。
【００２６】
本発明の光架橋性高分子固体電解質として好ましい例を下記に示すが、これらに限定されるものではない。
【化１０】

【００２７】
本発明の光架橋性高分子固体電解質は、光照射によって架橋することができる。光照射は窒素、アルゴンなどの不活性ガス中で行なうことが好ましい。処理時の温度は、室温〜２５０℃の範囲で行なうことができる。照射時間は、１秒〜１００時間の間で行なうことができる。光架橋をする際、本発明の高分子電解質そのものを熱処理して架橋体構造とすることもできるが、他の非架橋性ポリマーとの組成物としてから光架橋することもできる。その際、非架橋性ポリマーは本発明の架橋性ポリマーと同様にイオン性基を分子鎖中に含有するものでもイオン性基を含有しないものでもよい。非架橋性ポリマーの基本構造としては、例えばポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリエチレンナフタレート等のポリエステル類、ナイロン６、ナイロン６，６、ナイロン６，１０、ナイロン１２等のポリアミド類、ポリメチルメタクリレート、ポリメタクリル酸エステル類、ポリメチルアクリレート、ポリアクリル酸エステル類等のアクリレート系樹脂、ポリアクリル酸酸系樹脂、ポリメタクリル酸系樹脂、ジエン系ポリマーを含む各種ポリオレフィン、ポリウレタン系樹脂、酢酸セルロース、エチルセルロースなどのセルロース系樹脂、ポリアリレート、アラミド、ポリカーボネート、ポリフェニレンスルフィド、ポリフェニレンオキシド、ポリスルホン、ポリエーテルスルホン、ポリエーテルエーテルケトン、ポリエーテルイミド、ポリイミド、ポリベンズオキサゾール、ポリベンズチアゾール、ポリベンズイミダゾール、ポリアミドイミド等の芳香族系ポリマーなど、特に制限はない。
【００２８】
本発明の光架橋性高分子固体電解質は、膜に成形した後で架橋することで優れた高分子固体電解質膜となる。膜への成形は、キャスト、溶融成形など任意の方法で行なうことができるが、溶液からのキャストで作製することが好ましい。溶媒には、ジメチルスルホキシド、ジメチルアセトアミド、Ｎ−メチル−２−ピロリドン、ジメチルホルムアミドなど非プロトン性極性溶媒を用いることができる。溶液の濃度は１〜５０ｗｔ％であることが好ましい。溶液をガラス板上に流延し、溶媒を乾燥させることで膜を得ることができる。膜の厚みは、１〜５００μｍが好ましく、５〜１００μｍがより好ましい。必要に応じて、シリカなどの無機化合物や、他のポリマーなどを混合してもよい。イオン性基が塩になっている場合には、膜に成形した後、酸で処理することで酸型に変換することができる。その場合、架橋反応が終了した後で酸変換することが好ましい。膜を光処理する場合には、収縮などを防ぐため、適当な治具に固定して加熱することが好ましい。この場合も、本発明の高分子電解質そのものの成形体を熱処理して架橋体構造とすることもできるが、上述のような他の非架橋性ポリマーとの組成物成形体としてから光架橋することもできる。
【００２９】
本発明の高分子固体電解質膜は、水電解や燃料電池のプロトン交換膜として使用することができる。また、電極に触媒を接合する際のバインダーとして、本発明の高分子固体電解質を用いることができる。
【００３０】
【実施例】
以下、本発明について実施例を用いて具体的に説明するが、本発明はこれらの実施例に限定されることはない。各種測定は以下のようにして行なった。
【００３１】
（膜の厚み測定）
膜の厚みは膜厚計（ＰＥＡＫＯＣＫ ＤＩＧＩＴＡＬ ＧＡＵＧＥ Ｄ−１０／ＯＺＡＫＩ ＭＦＧ． ＣＯ．，ＬＴＤ）を用いて測定した。サンプル中のランダムな３点の厚みを測定し、それらを平均したものを膜の厚みとした。
【００３２】
（イオン伝導性測定）
自作測定用プローブ（ポリテトラフロロエチレン製）上で短冊状膜試料の表面に白金線（直径：０．２ｍｍ）を押しあて、８０℃９５％ＲＨの恒温・恒湿オーブン（（株）ナガノ科学機械製作所、ＬＨ−２０−０１）中に試料を保持し、白金線間の１０ＫＨｚにおける交流インピーダンスをＳＯＬＡＲＴＲＯＮ社１２５０ＦＲＥＱＵＥＮＣＹ ＲＥＳＰＯＮＳＥ ＡＮＡＬＹＳＥＲにより測定した。極間距離を変化させて測定し、極間距離と抵抗測定値をプロットした勾配から以下の式により膜と白金線間の接触抵抗をキャンセルした導電率を算出した。
導電率［Ｓ／ｃｍ］＝１／膜幅［ｃｍ］×膜厚［ｃｍ］×抵抗極間勾配［Ω／ｃｍ］
【００３３】
（ポリマー対数粘度）
ポリマー濃度０．２５ｇ／ｄｌのＮ−メチル−２−ピロリドン溶液について、オストワルド粘度計を用いて３０℃で測定した。
【００３４】
（耐水性試験）
ポリマー電解質膜５０ｍｇを５ｍｌのイオン交換水と共にガラスアンプル中に封入した。アンプルは１０５℃で３日間加熱した。冷却後アンプルを開封し、１Ｇ２のガラスフィルターで固形物を濾取した。フィルターは８０℃で一晩減圧乾燥し、濾過前後の重量から、固形分の重量を求め、重量減少率を求めた。
重量減少率［％］＝残留物重量［ｍｇ］／５０×１００
【００３５】
（イオン性基の定量）
ポリマー電解質膜１００ｍｇを０．０１ＮのＮａＯＨ水溶液５０ｍｌに浸漬し、２５℃で一晩攪拌した。その後、０．０５ＮのＨＣｌ水溶液で中和滴定した。中和滴定には、平沼産業株式会社製電位差滴定装置ＣＯＭＴＩＴＥ−９８０を用いた。イオン性基量は下記式で求められる。
イオン性基含有量［ｍｅｑ／ｇ］＝（１０−滴定量［ｍｌ］）／２
【００３６】
（実施例１）
４，４’−ジクロロジフェニルスルホン−３，３’−ジスルホン酸ソーダ３．９３０ｇ（８．０ｍｍｏｌ）、４，４’−ジフルオロベンゾフェノン０．４２８ｇ（２．０ｍｍｏｌ）、２，２−ビス（４−ヒドロキシ−３−メチルフェニル）プロパン２．５６３４ｇ（１０．０ｍｍｏｌ）、炭酸カリウム１．５８９ｇ（１１．５ｍｍｏｌ）、Ｎ−メチル−２−ピロリドン２０ｍｌ、トルエン３ｍｌを窒素導入管、攪拌翼、ディーンスタークトラップ、温度計を取り付けた１００ｍｌ枝付きフラスコに入れ、オイルバス中で攪拌しつつ窒素気流下で加熱した。トルエンとの共沸による脱水を１４０℃で行なった後、トルエンを全て留去した。その後２００℃に昇温し、１５時間加熱した。その後、室温まで冷却した溶液を５００ｍｌの純水に注ぎポリマーを再沈させた。濾過したポリマーは５０℃で減圧乾燥した。ポリマーの対数粘度は０．６６ｄｌ／ｇだった。得られたポリマー０．４ｇを１．６ｇのジメチルアセトアミドに溶解した溶液を、０．０２ｃｍの厚みでガラス板上にキャストし、７０℃で３日間減圧乾燥した。ガラス板から膜を剥離した後、金属製の枠に固定し、窒素雰囲気下５０℃で紫外線ランプで１時間光照射した。その後、膜を８０℃の１ｍｏｌ／Ｌ硫酸で１時間処理してスルホン酸基を酸型に変換し、さらに酸が検出できなくなるまで水で洗浄した。洗浄した膜は風乾したところ、厚み０．００３８ｃｍの透明な膜が得られた。膜のイオン性基濃度は２．３ｍｅｑ／ｇだった。耐水性試験での重量減少率は０％、イオン伝導性は０．３４Ｓ／ｃｍであり、良好な耐久性とイオン伝導性を示した。
【００３７】
（比較例１）
４，４’−ジクロロジフェニルスルホン−３，３’−ジスルホン酸ソーダ３．４３８ｇ（７．０ｍｍｏｌ）、４，４’−ジクロロジフェニルスルホン０．８６２ｇ（３．０ｍｍｏｌ）、ビフェノール１．８６２ｇ（１０．０ｍｍｏｌ）、炭酸カリウム１．５８９ｇ（１１．５ｍｍｏｌ）、Ｎ−メチル−２−ピロリドン１７ｍｌ、トルエン３ｍｌを窒素導入管、攪拌翼、ディーンスタークトラップ、温度計を取り付けた１００ｍｌ枝付きフラスコに入れ、オイルバス中で攪拌しつつ窒素気流下で加熱した。トルエンとの共沸による脱水を１４０℃で行なった後、トルエンを全て留去した。その後２００℃に昇温し、１５時間加熱した。室温まで冷却した溶液を５００ｍｌの純水に注ぎポリマーを再沈させた。濾過したポリマーは５０℃で減圧乾燥した。ポリマーの対数粘度は０．７５ｄｌ／ｇだった。得られたポリマー０．４ｇを１．６ｇのジメチルアセトアミドに溶解した溶液を、０．０２ｃｍの厚みでガラス板上にキャストし、７０℃で３日間減圧乾燥した。その後、膜を８０℃の１ｍｏｌ／Ｌ硫酸で１時間処理してスルホン酸基を酸型に変換し、さらに酸が検出できなくなるまで水で洗浄した。洗浄した膜は風乾したところ、厚み０．００３３ｃｍの透明な膜が得られた。膜のイオン性基濃度は２．３ｍｅｑ／ｇだった。耐水性試験では膜が溶解してしまい固形分が回収できなかった。イオン伝導性は０．２８Ｓ／ｃｍだった。
【００３８】
（比較例２）
４，４’−ジクロロジフェニルスルホン−３，３’−ジスルホン酸ソーダ１．２２８ｇ（２．５ｍｍｏｌ）、４，４’−ジクロロジフェニルスルホン２．１５４ｇ（７．５ｍｍｏｌ）、ビフェノール１．８６２ｇ（１０．０ｍｍｏｌ）、炭酸カリウム１．５８９ｇ（１１．５ｍｍｏｌ）、Ｎ−メチル−２−ピロリドン１７ｍｌ、トルエン３ｍｌを窒素導入管、攪拌翼、ディーンスタークトラップ、温度計を取り付けた１００ｍｌ枝付きフラスコに入れ、オイルバス中で攪拌しつつ窒素気流下で加熱した。トルエンとの共沸による脱水を１４０℃で行なった後、トルエンを全て留去した。その後２００℃に昇温し、１５時間加熱した。室温まで冷却した溶液を５００ｍｌの純水に注ぎポリマーを再沈させた。濾過したポリマーは５０℃で減圧乾燥した。ポリマーの対数粘度は０．８４ｄｌ／ｇだった。得られたポリマー０．４ｇを１．６ｇのジメチルアセトアミドに溶解した溶液を、０．０２ｃｍの厚みでガラス板上にキャストし、７０℃で３日間減圧乾燥した。その後、膜を８０℃の１ｍｏｌ／Ｌ硫酸で１時間処理してスルホン酸基を酸型に変換し、さらに酸が検出できなくなるまで水で洗浄した。洗浄した膜は風乾したところ、厚み０．００３１ｃｍの透明な膜が得られた。膜のイオン性基濃度は０．８ｍｅｑ／ｇだった。耐水性試験での重量減少率は０％だった。イオン伝導性は０．０７Ｓ／ｃｍと低かった。
【００３９】
【発明の効果】
本発明の光架橋性高分子固体電解質により、耐久性とイオン伝導性に優れる高分子固体電解質膜を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photocrosslinkable polymer solid electrolyte excellent in durability and ion conductivity, a polymer solid electrolyte membrane, and a method for producing the same.
[0002]
[Prior art]
As an example of an electrochemical device using a polymer solid electrolyte as an ionic conductor instead of a liquid electrolyte, a water electrolysis tank and a fuel cell can be mentioned. The polymer membrane used for these must have high proton conductivity as a cation exchange membrane and be sufficiently stable chemically, thermally, electrochemically and mechanically. For this reason, perfluorocarbon sulfonic acid membranes, mainly “Nafion (registered trademark)” manufactured by DuPont, USA, have been used as long-term usable products. However, if it is attempted to operate at a temperature exceeding 100 ° C., the moisture content of the membrane drops rapidly, and the membrane softens significantly. For this reason, in a fuel cell using methanol as a fuel, performance degradation occurs due to methanol permeation in the membrane, and sufficient performance cannot be exhibited. Further, even in a fuel cell that is currently studied mainly using hydrogen as a fuel and operated at around 80 ° C., it is pointed out that the cost of the membrane is too high as an obstacle to the establishment of fuel cell technology.
[0003]
As electrolyte membranes that can replace perfluorocarbon sulfonic acid membranes, so-called hydrocarbon polymer solid electrolytes in which ionic groups such as sulfonic acid groups are introduced into polymers such as polyether ether ketone, polyether sulfone, and polysulfone have been actively studied in recent years. ing. However, the hydrocarbon-based polymer solid electrolyte is more easily hydrated and swollen than perfluorocarbon sulfonic acid, and has a problem in durability under high humidity.
[0004]
As one of the measures for suppressing the swelling, mixing with a basic polymer is performed. This intends to suppress swelling by crosslinking the sulfonic acid group in the polymer solid electrolyte with a basic polymer. For example, a mixture of polyethersulfone having a sulfonic acid group or polyetheretherketone having a sulfonic acid group (acidic polymer) and polybenzimidazole (basic polymer) (International Patent Publication No. WO99 / 54389) Are known.
[0005]
Further, as described in JP-A-6-93114, International Publication No. WO99 / 6111, and JP-A-2001-522401, sulfonic acid groups that are ionic groups are crosslinked by covalent bonds. Therefore, the swelling is also suppressed.
[0006]
Although any of the above methods can suppress swelling, there is a problem that the ionic conductivity is lowered because the ionic group does not exhibit ionicity due to the crosslinking reaction.
[0007]
A sulfonated product of a styrene / divinylbenzene copolymer as a polymer solid electrolyte having a crosslinked structure is well known for being used in an early polymer electrolyte fuel cell. This polymer solid electrolyte was poor in durability of the polymer skeleton itself and did not show satisfactory properties as a fuel cell. JP-A-2-248434 and JP-A-2-245535 describe ion exchangers obtained by crosslinking reaction of chloromethyl groups in a polymer using a Lewis acid as a catalyst. However, a catalyst is required for the crosslinking reaction. Therefore, when a polymer and a catalyst are mixed to obtain a molded product, the catalyst remains, and when the polymer molded product is treated with a catalyst, a cross-linking reaction hardly occurs inside.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a photocrosslinkable polymer solid electrolyte excellent in ion conductivity and durability, suitable for a proton exchange membrane such as a fuel cell. It is to provide a manufacturing method.
[0009]
[Means for Solving the Problems]
The present inventors have made intensive studies, found that the above object can be achieved by using the manufacturing method of the crosslinked polymer solid electrolyte described below.
[0010]
That is, the present invention is represented by (1) one or more ionic groups selected from the group consisting of sulfonic acid groups or phosphonic acid groups or salts thereof in the molecule, and the following general formulas (1) and (2). A polymer solid electrolyte having at least one photocrosslinkable group consisting of a group having a polymer main chain of polyethersulfone or polyetherketone and a precursor thereof. A method for producing a crosslinked polymer solid electrolyte, wherein light irradiation is performed in an inert gas ,
[Chemical 1]

(In the formula, R represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n represents an integer of 1 to 4).
(2) The method for producing a crosslinked polymer solid electrolyte according to (1), wherein the inert gas is nitrogen or argon,
[0011]
(3) Light comprising one or more ionic groups selected from the group consisting of a sulfonic acid group or a phosphonic acid group or a salt thereof in the molecule, and groups represented by the following general formulas (1) and (2) A step of obtaining a crosslinked polymer solid electrolyte membrane by irradiating light with a polymer solid electrolyte membrane having at least one crosslinkable group and a polymer main chain of polyethersulfone or polyetherketone and a precursor thereof. In the method for producing a crosslinked polymer solid electrolyte membrane characterized by performing light irradiation in an inert gas,
[Chemical 2]

(In the formula, R represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n represents an integer of 1 to 4).
(4) The method for producing a crosslinked polymer solid electrolyte membrane according to (3), wherein the inert gas is nitrogen or argon.
(5) The method for producing a crosslinked polymer solid electrolyte membrane according to (3) or (4), wherein light irradiation is performed with the membrane fixed to a jig.
(6) A crosslinked polymer solid electrolyte produced by the method according to (1) or (2).
(7) A crosslinked polymer solid electrolyte membrane produced by the method according to (3) to (5).
(8) A fuel cell using the solid polymer electrolyte according to (6).
(9) A fuel cell using the solid polymer electrolyte membrane according to (7).
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. The photocrosslinkable polymer solid electrolyte in the present invention needs to have at least one photocrosslinkable group and an ionic group in the polymer molecule. The number average molecular weight of the polymer is preferably between 1,000 and 1,000,000, and is preferably between 5,000 and 500,000 because the balance between physical properties and processability can be achieved.
[0013]
The ionic group is one or more ionic groups selected from the group consisting of sulfonic acid groups and phosphonic acid groups and salts thereof.
A sulfonic acid group is preferable because it has high ion conductivity and a phosphonic acid group exhibits ion conductivity even at high temperatures. The amount of ionic groups in the polymer is preferably 0.1 to 5.0 mmol / g, more preferably 1.0 to 3.0 mmol / g. An ionic group can be introduced into the polymer by copolymerization of a monomer having an ionic group or a sulfonation reaction of the polymer. Examples of the monomer having an ionic group include the following compounds.
[0014]
[Chemical 3]

In addition, a sulfonic acid group can be introduced into the polymer using a sulfonating agent such as sulfuric anhydride, a complex of sulfuric anhydride, fuming sulfuric acid, concentrated sulfuric acid, or chlorosulfonic acid. A method of reacting a sulfonating agent in a state where the polymer is dissolved in a solvent inert to the sulfonating agent, a method of reacting a sulfonating agent in a state where the polymer is swollen with an appropriate solvent, or a direct sulfonation of the polymer The sulfonation reaction can be carried out by a method such as a method of reacting with an agent. The sulfonating agent may be used as it is, or may be used in a state dissolved and dispersed in an appropriate solvent. Reaction temperature can be performed between -100-100 degreeC.
[0015]
Examples of photocrosslinkable groups include benzophenone groups, α-diketone groups, acyloin groups, acyloin ether groups, benzyl alkyl ketal groups, acetophenone groups, polynuclear quinones, thioxanthone groups, acylphosphine groups, and ethylenically unsaturated groups. Can be mentioned. Among them, a combination of a group capable of generating a radical by light such as a benzophenone machine and a group capable of reacting with a radical such as an aromatic group having a hydrocarbon group such as a methyl group or an ethyl group is preferable. Can include the following groups.
[0016]
[Formula 4]

These groups can exist as main chains, side chains, and end groups in the polymer. The amount of the photocrosslinkable group in the polymer is preferably 1 to 5,000 mmol / kg, and more preferably 5 to 5,000 mmol / kg. Such groups can be introduced into the polymer as copolymerizable monomers or terminal terminators. When using an ethylenically unsaturated group, light from benzophenones, α-diketones, acyloins, acyloin ethers, benzyl alkyl ketals, acetophenones, polynuclear quinones, thioxanthones, acylphosphines, etc. It is preferable to add a polymerization initiator.
[0017]
Polyether sulfone or polyether ketone can be used for the main chain of the polymer . Excellent durability and easy synthesis.
[0018]
Polyether sulfone and polyether ketone can be obtained by condensing an aromatic dihalogen compound having an electron-withdrawing group and a bisphenol compound. The condensation reaction can be carried out by a known method. For example, condensation can be performed by heating in the presence of a base in an organic solvent. Examples of the organic solvent include aprotic polar solvents such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N, N-dimethylformamide, sulfolane, and dimethyl sulfoxide. Of these, N-methyl-2-pyrrolidone is preferred. Examples of the base include potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide and the like. Of these, potassium carbonate is preferred. The water produced by the reaction of the bisphenol compound and the base can be removed by azeotropy with toluene or benzene. The azeotropic dehydration is preferably performed at 100 to 150 ° C. After the dehydration is completed, a condensation reaction can be performed. The condensation reaction can be carried out at 120 to 300 ° C. The reaction is preferably carried out in an inert gas atmosphere such as nitrogen or argon. After completion of the reaction, the solution can be reprecipitated by adding it to a solvent insoluble in polymers such as water and acetone. The reprecipitated polymer can be purified by a known method.
[0019]
Examples of the aromatic dihalogen compound include the following compounds.
[Chemical formula 5]

The following compounds can also be used for the purpose of introducing an ionic group into the polymer.
[0020]
[Chemical 6]

[0021]
Examples of the bisphenol compound include the following compounds.
[0022]
[Chemical 7]

[0023]
Examples of the monomer for introducing a radical generating group into the polymer include the following compounds.
[Chemical 8]

[0024]
Examples of the monomer for introducing a group that reacts with a radical into the polymer include the following compounds.
[Chemical 9]

[0025]
The radical generating group and the radical reactive group may be in the same polymer or in separate polymers. Two or more polymers having each group may be mixed, or a polymer having two groups may be used. When two or more kinds of polymers are used, the ionic group may be present in any polymer.
[0026]
Preferred examples of the photocrosslinkable polymer solid electrolyte of the present invention are shown below, but are not limited thereto.
[Chemical Formula 10]

[0027]
The photocrosslinkable solid polymer electrolyte of the present invention can be crosslinked by light irradiation. The light irradiation is preferably performed in an inert gas such as nitrogen or argon. The temperature during the treatment can be performed in the range of room temperature to 250 ° C. The irradiation time can be performed between 1 second and 100 hours. When photocrosslinking is performed, the polymer electrolyte itself of the present invention can be heat-treated to form a crosslinked structure, but it can also be photocrosslinked after being formed into a composition with another non-crosslinkable polymer. In that case, the non-crosslinkable polymer may contain an ionic group in the molecular chain as in the crosslinkable polymer of the present invention, or may contain no ionic group. Examples of the basic structure of the non-crosslinkable polymer include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamides such as nylon 6, nylon 6,6, nylon 6,10, and nylon 12, polymethyl methacrylate, Polyacrylates such as polymethacrylates, polymethylacrylates, polyacrylates, polyacrylate resins, polymethacrylate resins, various polyolefins including diene polymers, polyurethane resins, cellulose acetate, ethyl cellulose Cellulosic resins such as polyarylate, aramid, polycarbonate, polyphenylene sulfide, polyphenylene oxide, polysulfone, polyethersulfone, polyetheretherketone Polyetherimide, polyimide, polybenzoxazole, polybenzthiazole, polybenzimidazole, and aromatic polymers such as polyamide-imide, not particularly limited.
[0028]
The photocrosslinkable solid polymer electrolyte of the present invention becomes an excellent solid polymer electrolyte membrane by crosslinking after being formed into a membrane. The film can be formed by any method such as casting or melt molding, but it is preferably produced by casting from a solution. As the solvent, an aprotic polar solvent such as dimethyl sulfoxide, dimethylacetamide, N-methyl-2-pyrrolidone or dimethylformamide can be used. The concentration of the solution is preferably 1 to 50 wt%. A film can be obtained by casting the solution on a glass plate and drying the solvent. The thickness of the film is preferably 1 to 500 μm, more preferably 5 to 100 μm. As needed, you may mix inorganic compounds, such as a silica, another polymer. When the ionic group is a salt, it can be converted into an acid form by treatment with an acid after forming into a film. In that case, it is preferable to perform acid conversion after completion of the crosslinking reaction. When light-treating the film, it is preferable to heat it while fixing it to a suitable jig in order to prevent shrinkage and the like. In this case as well, the molded product of the polymer electrolyte itself of the present invention can be heat-treated to form a crosslinked structure, but it is photocrosslinked after forming a composition molded body with another non-crosslinkable polymer as described above. You can also.
[0029]
The polymer solid electrolyte membrane of the present invention can be used as a proton exchange membrane for water electrolysis or a fuel cell. Moreover, the polymer solid electrolyte of this invention can be used as a binder at the time of joining a catalyst to an electrode.
[0030]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to these Examples. Various measurements were performed as follows.
[0031]
(Measurement of film thickness)
The thickness of the film was measured using a film thickness meter (PEAKOCK DIGITAL GAUGE D-10 / OZAKI MFG. CO., LTD). The thickness of three random points in the sample was measured, and the average of them was taken as the film thickness.
[0032]
(Ion conductivity measurement)
A platinum wire (diameter: 0.2 mm) was pressed against the surface of a strip-shaped membrane sample on a probe for self-made measurement (made of polytetrafluoroethylene), and a constant temperature and humidity oven at 80 ° C and 95% RH (Nagano Science Co., Ltd.) The sample was held in Machine Works, LH-20-01), and the AC impedance at 10 KHz between the platinum wires was measured by SOLARTRON 1250 FREQUENCY RESPONSE ANALYSER. The measurement was performed while changing the distance between the electrodes, and the conductivity in which the contact resistance between the film and the platinum wire was canceled was calculated from the gradient obtained by plotting the distance between the electrodes and the measured resistance value.
Conductivity [S / cm] = 1 / film width [cm] × film thickness [cm] × resistance interelectrode gradient [Ω / cm]
[0033]
(Polymer logarithmic viscosity)
The N-methyl-2-pyrrolidone solution having a polymer concentration of 0.25 g / dl was measured at 30 ° C. using an Ostwald viscometer.
[0034]
(Water resistance test)
50 mg of polymer electrolyte membrane was sealed in a glass ampoule together with 5 ml of ion exchange water. The ampoule was heated at 105 ° C. for 3 days. After cooling, the ampule was opened, and the solid matter was collected with a 1G2 glass filter. The filter was dried under reduced pressure at 80 ° C. overnight, and the weight of solid content was determined from the weight before and after filtration to determine the weight reduction rate.
Weight reduction rate [%] = residue weight [mg] / 50 × 100
[0035]
(Quantification of ionic groups)
100 mg of the polymer electrolyte membrane was immersed in 50 ml of 0.01N NaOH aqueous solution and stirred at 25 ° C. overnight. Then, neutralization titration with 0.05N HCl aqueous solution was performed. For neutralization titration, a potentiometric titrator COMMITITE-980 manufactured by Hiranuma Sangyo Co., Ltd. was used. The amount of ionic groups is determined by the following formula.
Ionic group content [meq / g] = (10-titer [ml]) / 2
[0036]
Example 1
4,930 ′ (8.0 mmol) of sodium 4,4′-dichlorodiphenylsulfone-3,3′-disulfonate, 0.428 g (2.0 mmol) of 4,4′-difluorobenzophenone, 2,2-bis (4- Hydroxy-3-methylphenyl) propane 2.5634 g (10.0 mmol), potassium carbonate 1.589 g (11.5 mmol), N-methyl-2-pyrrolidone 20 ml, toluene 3 ml, nitrogen introduction tube, stirring blade, Dean Stark trap The flask was placed in a 100 ml branch flask equipped with a thermometer and heated in a nitrogen stream while stirring in an oil bath. After dehydration by azeotropy with toluene at 140 ° C., all the toluene was distilled off. Thereafter, the temperature was raised to 200 ° C. and heated for 15 hours. Thereafter, the solution cooled to room temperature was poured into 500 ml of pure water to reprecipitate the polymer. The filtered polymer was dried at 50 ° C. under reduced pressure. The logarithmic viscosity of the polymer was 0.66 dl / g. A solution obtained by dissolving 0.4 g of the obtained polymer in 1.6 g of dimethylacetamide was cast on a glass plate with a thickness of 0.02 cm, and dried under reduced pressure at 70 ° C. for 3 days. After peeling off the film from the glass plate, it was fixed to a metal frame and irradiated with a UV lamp at 50 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, the membrane was treated with 1 mol / L sulfuric acid at 80 ° C. for 1 hour to convert the sulfonic acid group to the acid form, and further washed with water until no acid could be detected. When the washed film was air-dried, a transparent film having a thickness of 0.0038 cm was obtained. The ionic group concentration of the membrane was 2.3 meq / g. The weight loss rate in the water resistance test was 0%, and the ionic conductivity was 0.34 S / cm, which showed good durability and ionic conductivity.
[0037]
(Comparative Example 1)
3,438 '(7.0 mmol) of 4,4'-dichlorodiphenylsulfone-3,3'-disulfonic acid soda, 0.862 g (3.0 mmol) of 4,4'-dichlorodiphenylsulfone, 1.862 g (10. 0 mmol), 1.589 g (11.5 mmol) of potassium carbonate, 17 ml of N-methyl-2-pyrrolidone and 3 ml of toluene into a 100 ml branch flask equipped with a nitrogen inlet tube, stirring blade, Dean-Stark trap, thermometer, and oil. The mixture was heated in a nitrogen stream while stirring in a bath. After dehydration by azeotropy with toluene at 140 ° C., all the toluene was distilled off. Thereafter, the temperature was raised to 200 ° C. and heated for 15 hours. The solution cooled to room temperature was poured into 500 ml of pure water to reprecipitate the polymer. The filtered polymer was dried at 50 ° C. under reduced pressure. The logarithmic viscosity of the polymer was 0.75 dl / g. A solution obtained by dissolving 0.4 g of the obtained polymer in 1.6 g of dimethylacetamide was cast on a glass plate with a thickness of 0.02 cm, and dried under reduced pressure at 70 ° C. for 3 days. Thereafter, the membrane was treated with 1 mol / L sulfuric acid at 80 ° C. for 1 hour to convert the sulfonic acid group to the acid form, and further washed with water until no acid could be detected. When the washed film was air-dried, a transparent film having a thickness of 0.0033 cm was obtained. The ionic group concentration of the membrane was 2.3 meq / g. In the water resistance test, the membrane was dissolved and the solid content could not be recovered. The ionic conductivity was 0.28 S / cm.
[0038]
(Comparative Example 2)
1,228 g (2.5 mmol) of sodium 4,4′-dichlorodiphenylsulfone-3,3′-disulfonate, 2.154 g (7.5 mmol) of 4,4′-dichlorodiphenylsulfone, 1.862 g (10.10) of biphenol. 0 mmol), 1.589 g (11.5 mmol) of potassium carbonate, 17 ml of N-methyl-2-pyrrolidone and 3 ml of toluene into a 100 ml branch flask equipped with a nitrogen inlet tube, stirring blade, Dean-Stark trap, thermometer, and oil. The mixture was heated in a nitrogen stream while stirring in a bath. After dehydration by azeotropy with toluene at 140 ° C., all the toluene was distilled off. Thereafter, the temperature was raised to 200 ° C. and heated for 15 hours. The solution cooled to room temperature was poured into 500 ml of pure water to reprecipitate the polymer. The filtered polymer was dried at 50 ° C. under reduced pressure. The logarithmic viscosity of the polymer was 0.84 dl / g. A solution obtained by dissolving 0.4 g of the obtained polymer in 1.6 g of dimethylacetamide was cast on a glass plate with a thickness of 0.02 cm, and dried under reduced pressure at 70 ° C. for 3 days. Thereafter, the membrane was treated with 1 mol / L sulfuric acid at 80 ° C. for 1 hour to convert the sulfonic acid group to the acid form, and further washed with water until no acid could be detected. When the washed film was air-dried, a transparent film having a thickness of 0.0031 cm was obtained. The ionic group concentration of the membrane was 0.8 meq / g. The weight loss rate in the water resistance test was 0%. The ionic conductivity was as low as 0.07 S / cm.
[0039]
【The invention's effect】
With the photocrosslinkable polymer solid electrolyte of the present invention, a polymer solid electrolyte membrane excellent in durability and ion conductivity can be obtained.

Claims (9)

In the molecule, a photocrosslinkable group comprising one or more ionic groups selected from the group consisting of sulfonic acid groups or phosphonic acid groups or salts thereof, and groups represented by the following general formulas (1) and (2) In the step of obtaining a crosslinked polymer solid electrolyte by irradiating light with a polymer solid electrolyte and a precursor thereof , wherein the polymer main chain is polyethersulfone or polyetherketone. A method for producing a crosslinked polymer solid electrolyte, which is performed in an inert gas .

(In the formula, R represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n represents an integer of 1 to 4). The method for producing a crosslinked polymer solid electrolyte according to claim 1, wherein the inert gas is nitrogen or argon. In the molecule, a photocrosslinkable group comprising one or more ionic groups selected from the group consisting of sulfonic acid groups or phosphonic acid groups or salts thereof, and groups represented by the following general formulas (1) and (2) In the step of obtaining a crosslinked polymer solid electrolyte membrane by irradiating light with a polymer solid electrolyte membrane and a precursor thereof , wherein the polymer main chain is polyether sulfone or polyether ketone. A method for producing a crosslinked polymer solid electrolyte membrane, wherein the irradiation is performed in an inert gas .

(In the formula, R represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n represents an integer of 1 to 4). The method for producing a crosslinked polymer solid electrolyte membrane according to claim 3, wherein the inert gas is nitrogen or argon. The method for producing a crosslinked polymer solid electrolyte membrane according to claim 3 or 4, wherein the film is irradiated with light while being fixed to a jig. A crosslinked polymer solid electrolyte produced by the method according to claim 1 . A crosslinked polymer solid electrolyte membrane produced by the method according to claim 3 . A fuel cell using the solid polymer electrolyte according to claim 6. A fuel cell using the solid polymer electrolyte membrane according to claim 7.