JP3850347B2 - Method for producing water-swellable polymer - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、水溶性増粘剤として応用可能なミクロゲルの形態をとる水膨潤性高分子の製造方法であり、熱ラジカル重合による逆相マイクロエマルション重合法に関するものである。
【０００２】
本発明により製造される水膨潤性高分子は、化粧品、医薬品及び衛生用品などの生活用品や、土木分野、農業分野での応用が可能である。
【０００３】
【従来の技術】
逆相乳化重合法により水溶性モノマーを重合する高分子の製造方法は学術的に幾つかの報告がある｛例えば、F. Candau et al. J. Colloid and Interface Science, 101(1) 167 (1984), J. Barton. Polymer International, 30 151 (1993), J. Hernabdez-Barajas et al. Polymer. 38 5623 (1997) など｝。
【０００４】
【発明が解決しようとする課題】
しかしながら、これらの報告例は界面活性剤を過剰に配合したＷ／Ｏエマルションの重合系に関するものであり、工業的な高分子の製造法としては不向きであった。
【０００５】
一方、産業上の応用例としては、例えば、特開平９−１２６１３号公報において、水吸収性のミクロゲル粒子を逆相乳化重合法で製造し、オムツあるいは生理用品に適するように一定以上の大きさに製造する方法が開示されている。また、特許第１９１１６２３号公報においては、アクリル酸を用いた逆相乳化重合法による増粘剤の製造方法が開示されている。
【０００６】
しかしながら、これらの逆相乳化重合法では、重合の場である水相の粒子径が制御されず、得られるミクロゲル状の水膨潤性高分子を増粘剤として応用する場合その効果が低く実用には適しない。
【０００７】
本発明者は、上述の観点から鋭意研究した結果、逆相乳化重合法において、重合系が一相Ｗ/Ｏマイクロエマルション又は微細Ｗ／Ｏエマルションになるように重合温度及び界面活性剤を選択することにより、分散相である水相の粒子径をナノオーダーで制御でき、好ましいミクロゲル状の水膨潤性高分子が製造できることを見出し、本発明を完成するに至った。
【０００８】
【課題を解決するための手段】
すなわち、本発明は、有機溶媒又は油分を分散媒とし水溶性エチレン性不飽和モノマー水溶液を分散相とする組成物からなり、前記有機溶媒がアルカン類又はシクロアルカン類であり、前記油分が非極性油分であり、前記水溶性エチレン性不飽和モノマーがジアルキルアクリルアミド又はアニオン性アクリルアミド誘導体又はカチオン性アクリルアミド誘導体であり、前記組成物が熱ラジカル重合温度において一相Ｗ/Ｏマイクロエマルション又は微細Ｗ/Ｏエマルションを形成するように選ばれた非イオン性界面活性剤を含有し、転相温度を有するラジカル重合系において、前記熱ラジカル重合温度をラジカル重合系の転相温度以上であって転相温度から２０℃を上回らない温度範囲で重合を行うことを特徴とする水膨潤性高分子の製造方法を提供するものである。
【００１０】
さらに、本発明は、前記転相温度を有するラジカル重合系において、水相と非イオン性界面活性剤との質量比が、水相／界面活性剤＝０．５〜２０である上記の水膨潤性高分子の製造方法を提供するものである。
【００１１】
また、本発明は、前記転相温度を有するラジカル重合系において、非イオン性界面活性剤濃度が1以上30質量％以下である上記の水膨潤性高分子の製造方法を提供するものである。
【００１２】
さらに、本発明は、前記水膨潤性高分子の0.5%水分散液の２５℃におけるずり速度1.0s-1での見掛け粘度が10000mPas以上である上記の水膨潤性高分子の製造方法を提供するものである。
【００１３】
また、本発明は、前記水膨潤性高分子の0.5%水分散液の２５℃における動的弾性率が、歪み1%以下、周波数範囲0.01〜10Hzの範囲でG'（貯蔵弾性率）＞G"（損失弾性率）である上記の水膨潤性高分子の製造方法を提供するものである。
【００１４】
さらに、本発明は、前記水溶性エチレン性不飽和モノマーが、ジメチルアクリルアミド及び２−アクリルアミド−２−メチルプロパンスルホン酸である上記の水膨潤性高分子の製造方法を提供するものである。
【００１５】
【発明の実施の形態】
以下、本発明について詳述する。
【００１６】
本発明の製造方法は、適宜選択された親水性疎水性バランス(HLB)に調整された界面活性剤を使用することにより、逆相乳化重合における重合系が一相Ｗ/Ｏマイクロエマルション又は微細Ｗ/Ｏエマルションを形成する条件、すなわち重合温度が重合系の転相温度以上であって転相温度から２０℃を上回らない温度範囲で重合を行うことにより、分散相である水溶性モノマー水溶液の液滴のサイズを制御してラジカル重合を行うことを特徴とする製造方法である。
本発明において、転相温度とは重合系の連続相がＯ/ＷからＷ/Ｏに変化する温度を意味する。また、重合温度の温度範囲が転相温度以上であって転相温度から２０℃を上回らない温度範囲とは、転相温度がＸ℃であった場合に、重合温度がＸ℃以上であって（Ｘ＋２０）℃以下であることを意味する。
【００１７】
一相Ｗ/Ｏマイクロエマルションとは熱力学的に安定に油相と水相が共存している状態で、油相が連続相となり水膨潤界面活性剤ミセルが分散した状態である。また、微細Ｗ/Ｏエマルションとは上記一相Ｗ/Ｏマイクロエマルション領域の近傍に発生する相であり、熱力学的には不安定であるが、速度論的に安定に油相と水相がＷ/Ｏエマルションとして存在する状態である。一般的に一相Ｗ/Ｏマイクロエマルションおよび微細Ｗ/Ｏエマルションの水相の粒子径は約10〜数100nm程度である。一相Ｗ/Ｏマイクロエマルションは熱力学的に平衡状態にあるのでその状態は重合系の組成と温度のみで決定され、機械的な攪拌条件に左右されない。また一相Ｗ/Ｏマイクロエマルション形成温度の上部近傍で生成する微細Ｗ/Ｏエマルションは通常の攪拌条件においても数10〜数100nm程度の微細Ｗ/Ｏを形成する。このことは工業的なスケールアップに極めて有利な製造法であることを意味する。
【００１８】
ラジカル重合系の「油相（有機溶媒又は油分からなる分散媒）/界面活性剤/水相（モノマー水溶液）」の三成分系において、形成する粒子径（水膨潤界面活性剤ミセルあるいは水滴）は水相/界面活性剤の量比に依存し、この比が小さいほど粒子系が小さくなる。それ故、量比が小さいほど（界面活性剤量が多いほど）微細な粒子を形成できるが、結果として界面活性剤の使用量が増大するので、工業的製造工程としては不適である。したがって、本発明のラジカル重合系における水相と界面活性剤の量の質量比は、水相／界面活性剤が０．５以上２０以下であることが好ましい。水相の量とは、水と水溶性エチレン性不飽和モノマーとからなるモノマー水溶液の量である。水に溶解する化合物が（例えば、重合開始剤等）ラジカル重合系に添加された場合はその化合物の量も含む。
水と水溶性エチレン性不飽和モノマーとの質量比は適宜決定されるが、水溶性エチレン性不飽和モノマーの含有量は水相全量に対して１０〜４０質量％が好ましく、１０〜３０質量％がさらに好ましい。
また、ラジカル重合系に含まれる界面活性剤の総量は、ラジカル重合系を構成する組成物全量に対して１質量％以上３０質量％以下が好ましい。界面活性剤の総量が１質量％を下回ると油相での臨界ミセル形成濃度を下回ることがあり、一相Ｗ/Ｏマイクロエマルションを形成できない場合がある。また、３０質量％以上では工業的製造に不向きである。
なお、水相と油相との質量比は、水相：油相＝１：９〜６：４が好ましい。
【００１９】
本発明の製造方法において、油相を構成する好ましい分散媒としての有機溶媒は、ペンタン、ヘキサン、ヘプタン、オクタン、ノナン、デカン、ウンデカンなどのアルカン類；シクロペンタン、シクロヘキサン、シクロヘプタン、シクロオクタンなどのシクロアルカン類が挙げられる。また、好ましい分散媒としての油分としてはパラフィン油などの非極性油分が挙げられる。
これらの分散媒は、水溶性エチレン性不飽和モノマーの種類や希望する転相温度に応じて適宜決定される。
【００２０】
本発明に適した界面活性剤の選択は基本的には転相温度を測定することで決定できる。転相温度とは連続相がＯ／ＷからＷ／Ｏに変化する温度、すなわち水相連続相から油相連続相に変化する温度である。本発明の製造方法において、この転相温度は所望の重合系を攪拌しながら温度を上昇させ、市販のテスターにより電気伝導度を測定し、電気伝導度が急激に低下して実質的にゼロになる温度として決定される。
上記のように決定される転相温度が希望する熱ラジカル重合温度になるように最適な界面活性剤の種類及び量が決定される。熱ラジカル重合温度は、水溶性エチレン性不飽和モノマー及び油相の種類に応じて適宜決定されるが、３０〜１００℃程度が好ましく、重合においては、熱ラジカル重合温度が転相温度＋20℃以内の温度範囲内に容易に制御出来る。
転相温度測定の例を図１に示す。図１は、ヘキサン/ポリオキシエチレン（６）オレイルエーテル/水溶性エチレン性不飽和モノマー水溶液の擬似三成分重合系の例である。この重合系においては、水溶性エチレン性不飽和モノマー水溶液としてジメチルアクリルアミドと２−アクリルアミド２−メチルプロパンスルホン酸をモル比で８０:２０の混合物を２０質量％でイオン交換水に溶解したものを用いている。この水溶性エチレン性不飽和モノマー水溶液とヘキサンを混合比（質量比）で10:90〜40:60の範囲で混合した混合液を調製した、その混合液全量に対してそれぞれポリオキシエチレン（６）オレイルエーテルを５質量％添加したサンプル溶液を調製した。それぞれの水溶性エチレン性不飽和モノマー水溶液とヘキサンを混合比が異なるサンプルの転相温度を系の電気伝導度を指標に決定した。図１において、Ｘ軸に水溶性エチレン性不飽和モノマー水溶液とヘキサンの混合比（例えば、X軸のn-Hexane/aqの値が70である場合、ヘキサンは70質量部であり残りの30質量部が水溶性エチレン性不飽和モノマー水溶液であることを示している。すなわちヘキサンと水溶性エチレン性不飽和モノマー水溶液の質量比が70:30であることを示している。）を、Ｙ軸は温度（摂氏）を示している。図中の実線が各サンプルの転相温度を結んだもので、所謂可溶化限界曲線と呼ばれるものである。点線は、上記転相温度＋20℃の点を結んだものである。この実線と点線に囲まれた領域Ａが一相Ｗ／Ｏマイクロエマルション〜微細Ｗ／Ｏエマルションが生成する領域である。
本発明においては、分散媒と水溶性エチレン性不飽和モノマーの種類、混合比を選択して重合系を調製し、この系の転相温度が熱ラジカル重合温度（30〜100℃程度）に一致するような界面活性剤を選ぶことで、ある最適な温度範囲（転相温度＋20℃）で微細なミクロゲルの形態の水膨潤性高分子を製造することが出来る。熱ラジカル重合自体はＡ領域で重合を行う限り、公知のラジカル重合開始剤を使用して公知の方法により行うことが出来る。なお、光重合開始剤も用いることは可能であるが、工業的な量産には不向きである。
【００２１】
本発明の製造方法において、好ましい界面活性剤は、転相の温度依存性が大きい非イオン性界面活性剤である。その化学種には制限がなく、所望の重合系組成物において実際に電気伝導度を測定したり、分散媒／界面活性剤／水溶性エチレン性不飽和モノマーの３成分系の相図を作成したりして、当該重合系組成物に適した界面活性剤の一種又は二種以上の組み合わせが決定される。
好ましい界面活性剤の具体例としては、ポリオキシエチレンセチルエーテル、ポリオキシエチレンオレイルエーテル、ポリオキシエチレンステアリルエーテル、ポリオキシエチレンノニルフェニルエーテル、ポリオキシエチレンラウリルエーテル、ポリオキシエチレンヘキシルデシルエーテル、ポリオキシエチレンイソステアリルエーテル、ポリオキシエチレンオクチルドデシルエーテル、ポリオキシエチレンベヘニルエーテル、ポリオキシエチレンコレステリルエーテル、ポリオキシエチレン硬化ひまし油、ソルビタン脂肪酸エステル、モノ脂肪酸グリセリン、トリ脂肪酸グリセリン、ポリグリセリン脂肪酸エステル、イソステアリン酸ポリオキシエチレングリセリン、トリイソステアリン酸ポリオキシエチレングリセリン、モノステアリン酸ポリオキシエチレングリセリン、ジステアリン酸ポリオキシエチレングリセリル、トリステアリン酸ポリオキシエチレンルリセリルなどが挙げられる。
【００２２】
水溶性エチレン性不飽和モノマーは、非イオン性モノマーとイオン性モノマー（アニオン性モノマー若しくはカチオン性モノマー）とを併用することが好ましい。
非イオン性モノマーはジアルキルアクリルアミドが好ましい。
イオン性モノマーはアニオン性アクリルアミド誘導体またはカチオン性アクリルアミド誘導体が好ましい。
特に好ましいジアルキルアクリルアミドは、ジメチルアクリルアミド、ジエチルアクリルアミドである。
特に好ましいイオン性アクリルアミド誘導体は、2-アクリルアミド2-メチルプロパンスルホン酸およびその塩である。
特に好ましいカチオン性アクリルアミド誘導体はN,N,-ジメチルアミノプロピルアクリルアミドメチルクロライドである。
非イオン性モノマーとイオン性モノマーの重合系におけるモノマー組成比（重合系の仕込み比）は、目的とするミクロゲルのモノマー構成比に応じて適宜任意に決定される。ミクロゲルのモノマー構成比と重合系への仕込み比はほぼ同一となる。非イオン性モノマーとイオン性モノマーの重合系の仕込み比（モル比）は、通常、非イオン性モノマー：イオン性モノマー＝０．５：９．５〜９．５：０．５、好ましくは１：９〜９：１、さらに好ましくは７：３〜９：１の範囲で共重合に供される。最適比率は、非イオン性モノマー：イオン性モノマー＝８：２である。
上記の水溶性エチレン性不飽和モノマーを任意に選択して本発明の水膨潤性高分子が重合される。本発明の製造方法において、特に好ましくは、水溶性エチレン性不飽和モノマーにジメチルアクリルアミドと２−アクリルアミド−２−メチルプロパンスルホン酸を用い、これらのモノマーから共重合される２元共重合体のミクロゲルからなる水膨潤性高分子を重合する製造方法である。本発明の製造法において、架橋モノマーは必要がなく自己架橋により優れた増粘効果を有する水膨潤性高分子が得られる。
【００２３】
上記の如く本発明の製造方法は、例えば下記のステップにて実施されて水膨潤性高分子が製造される。
（１）分散相の水溶性エチレン性不飽和モノマー水溶液と、分散媒の有機溶媒又は油分とを含有する組成物に任意の界面活性剤を混合して、電気伝導度が０になる温度（転相温度）を測定する。
（２）この転相温度から２０℃を越えない範囲の任意の温度（好ましくは転相温度より５〜１０℃高い温度）が、制御可能な希望する任意の熱ラジカル重合温度（好ましくは３０℃以上１００℃以下）になるように、上記の任意の界面活性剤（その種類若しくは二種以上の組み合わせ）及びその配合量を決定する。
（３）上記により決定された重合系組成物において、上記の制御可能な希望する任意の熱ラジカル重合温度に維持して熱ラジカル重合を行う。熱ラジカル重合温度が上記転相温度から２０℃を越えない範囲に維持されていれば良いが、転相温度から５〜１０℃高い温度に維持することが好ましい。
（４）上記の方法により、重合系組成物の転相温度が制御可能な希望する熱ラジカル重合温度にならなければ、分散媒の有機溶媒又は油分を変更したり、水溶性エチレン性不飽和モノマー水溶液（水相）と、有機溶媒又は油分（油相）との組成を適宜変更したりして、上記方法により重合系組成物に用いる界面活性剤及びその配合量を決定する。
【００２４】
本発明の製造方法により得られる水膨潤性高分子の水分散液は、下記（１）、および（２）のレオロジー的性質を有する。
水膨潤性高分子の0.5%（質量百分率）の水分散液の見掛け粘度がずり速度1.0s-1において10000mPas以上である。
水膨潤性高分子の0.5%（質量百分率）の水分散液の動的弾性率が歪み１％以下、周波数範囲0.01〜10Hzの範囲でG'>G"である。
なお、水膨潤性高分子の水分散液の見掛け粘度とはコーンプレート型レオメーター（Paar Physica製 MCR-300）を用い、測定温度２５℃、ずり速度1.0s-1における粘度である。また、動的弾性率は、同上の測定装置を用いて測定温度２５℃、歪み１％以下、周波数範囲0.01〜10Hzで測定した貯蔵弾性率（G'）および損失弾性率(G")の値を意味する。
これらの物性値は上記装置に限らず市販のレオメータによっても測定可能である。
【００２５】
【実施例】
次に実施例によって本発明をさらに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ものではない。
【００２６】
「実施例１」
ジメチルアクリルアミド（興人製）を40gと2-アクリルアミド-2-メチルプロパンスルホン酸（Sigma製）9gを250gのイオン交換水に溶解し水酸化ナトリウムでpH=7.0に調整する。還流装置を備えた1000mL４つ口フラスコにn-ヘキサン250gポリオキシエチレン(3)オレイルエーテル(エマレックス503、日本エマルション製)8.2gおよびポリオキシエチレン(6)オレイルエーテル(エマレックス506、日本エマルション製)16.4gを入れ混合溶解しN2置換する。この四つ口フラスコにモノマー水溶液を添加してN2雰囲気下攪拌しながらオイルバスで６５〜７０℃まで徐々に加熱する。
この重合系組成物の電気伝導度をテスターにてモニターし、電気伝導度が急激に低下し実質的に０になる温度を転相温度とし（５９℃）、この温度から２０℃を上回らないように重合温度を６５℃に制御する。
次に重合系組成物が半透明の状態になっていることを確認した後、過硫酸アンモニウム0.2gを重合系組成物に添加し重合を開始する。重合系を攪拌しながら上述の温度に４時間維持することで水膨潤性高分子が生成する。
重合終了後重合液に多量のアセトンを加えて水膨潤性高分子を沈殿させ、引き続きアセトンで３回洗浄し、残存モノマーおよび界面活性剤を除去する。沈殿物はろ過後減圧乾燥し、白色粉末状の水膨潤高分子乾燥物を得た。収率は96%であった。得られた水膨潤性高分子の0.5%イオン交換水分散液を調製し、見掛け粘度および動的弾性率測定を行った。
見掛けの粘度、転相温度および重合温度の結果を表１に、動的弾性率の結果を図２に示す。
【００２７】
「実施例２」
ジメチルアクリルアミド（興人製）を35gと2-アクリルアミド-2-メチルプロパンスルホン酸（Sigma製）17.5gを250gのイオン交換水に溶解し水酸化ナトリウムでpH=7.0に調整する。還流装置を備えた1000mL４つ口フラスコにn-ヘキサン250gポリオキシエチレン(3)オレイルエーテル(エマレックス503、日本エマルション製)8.2gおよびポリオキシエチレン(6)オレイルエーテル(エマレックス506、日本エマルション製)16.4gを入れ混合溶解しN2置換する。この四つ口フラスコにモノマー水溶液を添加してN2雰囲気下攪拌しながらオイルバスで６５〜７０℃まで徐々に加熱する。
この重合系組成物の電気伝導度をテスターにてモニターし、電気伝導度が急激に低下し実質的に０になる温度を転相温度とし（６０℃）、この温度から２０℃を上回らないように重合温度を６５℃に制御する。
次に重合系組成物が半透明の状態になっていることを確認した後、過硫酸アンモニウム0.2gを重合系組成物に添加し重合を開始する。重合系を攪拌しながら上述の温度に４時間維持することで水膨潤性高分子が生成する。
重合終了後重合液に多量のアセトンを加えて水膨潤性高分子を沈殿させ、引き続きアセトンで３回洗浄し、残存モノマーおよび界面活性剤を除去する。沈殿物はろ過後減圧乾燥し、白色粉末状の水膨潤高分子乾燥物を得た。収率は95%であった。得られた水膨潤性高分子の0.5%イオン交換水分散液を調製し、見掛け粘度および動的弾性率測定を行った。
見掛けの粘度、転相温度および重合温度の結果を表１に、動的弾性率の結果を図３に示す。
【００２８】
「実施例３」
ジメチルアクリルアミド（興人製）を30gと2-アクリルアミド-2-メチルプロパンスルホン酸（Sigma製）26.7gを250gのイオン交換水に溶解し水酸化ナトリウムでpH=7.0に調整する。還流装置を備えた1000mL４つ口フラスコにn-ヘキサン250gポリオキシエチレン(3)オレイルエーテル(エマレックス503、日本エマルション製)8.2gおよびポリオキシエチレン(6)オレイルエーテル(エマレックス506、日本エマルション製)16.4gを入れ混合溶解しN2置換する。この四つ口フラスコにモノマー水溶液を添加してN2雰囲気下攪拌しながらオイルバスで６５〜７０℃まで徐々に加熱する。
この重合系組成物の電気伝導度をテスターにてモニターし、電気伝導度が急激に低下し実質的に０になる温度を転相温度とし（５５℃）、この温度から２０℃を上回らないように重合温度を６８℃に制御する。
次に重合系組成物が半透明の状態になっていることを確認した後、過硫酸アンモニウム0.2gを重合系組成物に添加し重合を開始する。重合系を攪拌しながら上述の温度に４時間維持することで水膨潤性高分子が生成する。
重合終了後重合液に多量のアセトンを加えて水膨潤性高分子を沈殿させ、引き続きアセトンで３回洗浄し、残存モノマーおよび界面活性剤を除去する。沈殿物はろ過後減圧乾燥し、白色粉末状の水膨潤高分子乾燥物を得た。収率は95%であった。得られた水膨潤性高分子の0.5%イオン交換水分散液を調製し、見掛け粘度および動的弾性率測定を行った。
見掛けの粘度、転相温度および重合温度の結果を表１に、動的弾性率の結果を図４に示す。
【００２９】
「比較例：Ａ領域からはずれた範囲で重合した例」
ジメチルアクリルアミド（興人製）を35gと2-アクリルアミド-2-メチルプロパンスルホン酸（Sigma製）17.5gを250gのイオン交換水に溶解し水酸化ナトリウムでpH=7.0に調整する。還流装置を備えた1000mL四つ口フラスコにn-ヘキサン250g、ポリオキシエチレン(3)オレイルエーテル（エマレックス503、日本エマルション製）16.4gおよびポリオキシエチレン(6)オレイルエーテル（エマレックス506、日本エマルション製）8.2gを入れ混合溶解しN2置換する。この四つ口フラスコにモノマー水溶液を添加してN2雰囲気下攪拌しながらオイルバスで65〜70℃まで徐々に加熱する。
この重合系組成物の電気伝導度をテスターにてモニターし、電気伝導度が急激に低下し実質的に０になる温度を転相温度とし（２３℃）、この温度から２０℃を上回るように重合温度を６６℃に制御する。
次に過硫酸アンモニウム0.2gを重合系組成物に添加し重合を開始する。重合系を攪拌しながら上述の温度に４時間維持することで水膨潤性高分子が生成する。重合終了後重合液に多量のアセトンを加えて水膨潤性高分子を沈殿させ、引き続きアセトンで３回洗浄し、残存モノマーおよび界面活性剤を除去する。沈殿物はろ過後減圧乾燥し、白色粉末状の水膨潤性高分子感想物を得た。収率は９６％であった。得られた水膨潤性高分子の0.5%イオン交換水分散液を調製し見掛け粘度の測定を行った。
見掛け粘度、転相温度および重合温度の結果を表１に示す。
【００３０】
【表１】
(2)電気伝導度がゼロに変化した温度
(3)重合時の重合系組成物の平均温度
【００３１】
【発明の効果】
本発明の製造方法によれば、優れた増粘効果を有する水膨潤性高分子を容易に製造できる。
本発明の製造方法によりラジカル重合された水膨潤性高分子はミクロゲルの形態をとり粉末状態で得られ、増粘剤の用途に使用するにあたって、従来の製造方法により得られる高分子ゲルのように粉砕する必要がないという利点を有する。
【図面の簡単な説明】
【図１】ヘキサン（Ｏ）/界面活性剤/水溶性エチレンモノマー水溶液（Ｗ）の３成分の重合系組成物の相図である。
【図２】実施例１により得られた水膨潤性高分子の水分散液の動的弾性率を表わすグラフである。
【図３】実施例２により得られた水膨潤性高分子の水分散液の動的弾性率を表わすグラフである。
【図４】実施例３により得られた水膨潤性高分子の水分散液の動的弾性率を表わすグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a water-swellable polymer in the form of a microgel applicable as a water-soluble thickener, and relates to a reverse phase microemulsion polymerization method by thermal radical polymerization.
[0002]
The water-swellable polymer produced according to the present invention can be applied to daily necessities such as cosmetics, pharmaceuticals and hygiene products, as well as in the civil engineering and agricultural fields.
[0003]
[Prior art]
There have been several reports on the production of polymers that polymerize water-soluble monomers by reversed-phase emulsion polymerization {for example, F. Candau et al. J. Colloid and Interface Science, 101 (1) 167 (1984 ), J. Barton. Polymer International, 30 151 (1993), J. Hernabdez-Barajas et al. Polymer. 38 5623 (1997)}.
[0004]
[Problems to be solved by the invention]
However, these reported examples relate to a polymerization system of a W / O emulsion containing an excessive amount of a surfactant, and are not suitable as an industrial polymer production method.
[0005]
On the other hand, as an industrial application example, for example, in Japanese Patent Application Laid-Open No. 9-12613, water-absorbable microgel particles are produced by a reverse phase emulsion polymerization method, and the size is more than a certain size so as to be suitable for diapers or sanitary products. Discloses a method of manufacturing. Japanese Patent No. 1911623 discloses a method for producing a thickener by a reverse emulsion polymerization method using acrylic acid.
[0006]
However, these inverse emulsion polymerization methods do not control the particle size of the aqueous phase, which is the polymerization site, and are less effective when applied to the resulting microgel water-swellable polymer as a thickener. Is not suitable.
[0007]
As a result of intensive research from the above viewpoint, the present inventor selects a polymerization temperature and a surfactant so that the polymerization system becomes a single-phase W / O microemulsion or a fine W / O emulsion in the reverse phase emulsion polymerization method. As a result, it was found that the particle diameter of the aqueous phase, which is the dispersed phase, can be controlled on the nano order, and a preferable microgel-like water-swellable polymer can be produced, and the present invention has been completed.
[0008]
[Means for Solving the Problems]
That is, the present invention comprises a composition having an organic solvent or oil as a dispersion medium and a water-soluble ethylenically unsaturated monomer aqueous solution as a dispersion phase , wherein the organic solvent is an alkane or cycloalkane, and the oil is nonpolar. An oil component, the water-soluble ethylenically unsaturated monomer is a dialkylacrylamide, an anionic acrylamide derivative or a cationic acrylamide derivative, and the composition is a one-phase W / O microemulsion or a fine W / O emulsion at a thermal radical polymerization temperature. contain non-ionic surfactant materials selected to form the in radical polymerization system having a phase inversion temperature, the thermal radical polymerization temperature be in the phase inversion temperature or more radical polymerization from the phase inversion temperature 20 A method for producing a water-swellable polymer, characterized by performing polymerization in a temperature range not exceeding ℃ It is intended to provide.
[0010]
Furthermore, the present invention, the in radical polymerization system having a phase inversion temperature, the mass ratio of water phase and a nonionic surfactant, an aqueous phase / surfactant = 0.5 to 20 above water-swellable A method for producing a conductive polymer is provided.
[0011]
The present invention also provides a method for producing the water-swellable polymer as described above, wherein the concentration of the nonionic surfactant is 1 to 30% by mass in the radical polymerization system having the phase inversion temperature .
[0012]
Furthermore, the present invention provides a method for producing the above water-swellable polymer, wherein the apparent viscosity of a 0.5% aqueous dispersion of the water-swellable polymer at a shear rate of 1.0 s −1 at 25 ° C. is 10,000 mPas or more. Is.
[0013]
In the present invention, the dynamic elastic modulus at 25 ° C. of a 0.5% aqueous dispersion of the water-swellable polymer is such that G ′ (storage elastic modulus)> G when the strain is 1% or less and the frequency range is 0.01 to 10 Hz. The present invention provides a method for producing the above water-swellable polymer having (loss elastic modulus).
[0014]
Furthermore, the present invention provides a method for producing the above water-swellable polymer, wherein the water-soluble ethylenically unsaturated monomer is dimethylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0016]
In the production method of the present invention, by using a surfactant adjusted to an appropriately selected hydrophilic and hydrophobic balance (HLB), the polymerization system in the reverse phase emulsion polymerization is a one-phase W / O microemulsion or a fine W. A solution of a water-soluble monomer aqueous solution that is a dispersed phase by performing polymerization in the conditions for forming the / O emulsion, that is, the polymerization temperature is equal to or higher than the phase inversion temperature of the polymerization system and does not exceed 20 ° C. from the phase inversion temperature. The production method is characterized in that radical polymerization is carried out by controlling the size of the droplets.
In the present invention, the phase inversion temperature means a temperature at which the continuous phase of the polymerization system changes from O / W to W / O. In addition, the temperature range of the polymerization temperature is equal to or higher than the phase inversion temperature and does not exceed 20 ° C. from the phase inversion temperature. When the phase inversion temperature is X ° C., the polymerization temperature is equal to or higher than X ° C. It means (X + 20) ° C. or lower.
[0017]
A one-phase W / O microemulsion is a state in which an oil phase and a water phase coexist thermodynamically and stably, and the oil phase becomes a continuous phase and water-swelling surfactant micelles are dispersed. The fine W / O emulsion is a phase generated in the vicinity of the one-phase W / O microemulsion region, and is thermodynamically unstable, but the kinetically stable oil phase and water phase. It is a state which exists as a W / O emulsion. In general, the particle size of the aqueous phase of the single-phase W / O microemulsion and the fine W / O emulsion is about 10 to several hundred nm. Since the single-phase W / O microemulsion is in a thermodynamic equilibrium state, the state is determined only by the composition and temperature of the polymerization system and does not depend on the mechanical stirring conditions. The fine W / O emulsion produced near the upper part of the temperature for forming the single-phase W / O microemulsion forms fine W / O of about several tens to several hundreds of nanometers even under normal stirring conditions. This means that the production method is extremely advantageous for industrial scale-up.
[0018]
In the three-component system of radical polymerization system “oil phase (dispersion medium consisting of organic solvent or oil) / surfactant / water phase (monomer aqueous solution)”, the particle size (water-swelling surfactant micelles or water droplets) formed is Depending on the amount ratio of aqueous phase / surfactant, the smaller this ratio, the smaller the particle system. Therefore, the smaller the amount ratio (the larger the amount of the surfactant), the finer particles can be formed. However, the amount of the surfactant used increases as a result, which is not suitable for an industrial production process. Accordingly, the mass ratio of the amount of the aqueous phase and the surfactant in the radical polymerization system of the present invention is preferably such that the aqueous phase / surfactant is 0.5 or more and 20 or less. The amount of the aqueous phase is the amount of an aqueous monomer solution composed of water and a water-soluble ethylenically unsaturated monomer. When a compound that dissolves in water (for example, a polymerization initiator) is added to the radical polymerization system, the amount of the compound is also included.
The mass ratio of water to the water-soluble ethylenically unsaturated monomer is appropriately determined, but the content of the water-soluble ethylenically unsaturated monomer is preferably 10 to 40% by mass, and 10 to 30% by mass with respect to the total amount of the aqueous phase. Is more preferable.
Further, the total amount of the surfactant contained in the radical polymerization system is preferably 1% by mass or more and 30% by mass or less with respect to the total amount of the composition constituting the radical polymerization system. If the total amount of the surfactant is less than 1% by mass, the critical micelle formation concentration in the oil phase may be lowered, and a one-phase W / O microemulsion may not be formed. Moreover, if it is 30 mass% or more, it is unsuitable for industrial manufacture.
The mass ratio of the water phase to the oil phase is preferably water phase: oil phase = 1: 9 to 6: 4.
[0019]
In the production method of the present invention, the organic solvent as a preferable dispersion medium constituting the oil phase is alkanes such as pentane, hexane, heptane, octane, nonane, decane, undecane; cyclopentane, cyclohexane, cycloheptane, cyclooctane, etc. Of the cycloalkanes. Moreover, non-polar oils, such as paraffin oil, are mentioned as an oil component as a preferable dispersion medium.
These dispersion media are appropriately determined according to the type of water-soluble ethylenically unsaturated monomer and the desired phase inversion temperature.
[0020]
The selection of a surfactant suitable for the present invention can basically be determined by measuring the phase inversion temperature. The phase inversion temperature is a temperature at which the continuous phase changes from O / W to W / O, that is, a temperature at which the water phase continuous phase changes to the oil phase continuous phase. In the production method of the present invention, the phase inversion temperature is increased while stirring the desired polymerization system, and the electrical conductivity is measured with a commercially available tester, and the electrical conductivity is rapidly reduced to substantially zero. Is determined as a temperature.
The optimum type and amount of the surfactant are determined so that the phase inversion temperature determined as described above becomes a desired thermal radical polymerization temperature. The thermal radical polymerization temperature is appropriately determined according to the type of the water-soluble ethylenically unsaturated monomer and the oil phase, but is preferably about 30 to 100 ° C. In the polymerization, the thermal radical polymerization temperature is within the phase inversion temperature + 20 ° C. Can be easily controlled within the temperature range.
An example of phase inversion temperature measurement is shown in FIG. FIG. 1 is an example of a pseudo ternary polymerization system of hexane / polyoxyethylene (6) oleyl ether / water-soluble ethylenically unsaturated monomer aqueous solution. In this polymerization system, a water-soluble ethylenically unsaturated monomer aqueous solution in which a mixture of dimethylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 80:20 is dissolved in ion exchange water at 20% by mass is used. ing. Mixtures of this water-soluble ethylenically unsaturated monomer aqueous solution and hexane were mixed at a mixing ratio (mass ratio) of 10:90 to 40:60. Polyoxyethylene (6 ) A sample solution to which 5% by mass of oleyl ether was added was prepared. The phase inversion temperature of each sample having a different mixing ratio of each water-soluble ethylenically unsaturated monomer aqueous solution and hexane was determined using the electrical conductivity of the system as an index. In FIG. 1, the mixing ratio of a water-soluble ethylenically unsaturated monomer aqueous solution and hexane on the X axis (for example, when the value of n-Hexane / aq on the X axis is 70, hexane is 70 parts by mass and the remaining 30 masses) Part is a water-soluble ethylenically unsaturated monomer aqueous solution, that is, the mass ratio of hexane and water-soluble ethylenically unsaturated monomer aqueous solution is 70:30.) Indicates temperature (Celsius). The solid line in the figure connects the phase inversion temperatures of each sample and is called a so-called solubilization limit curve. The dotted line connects the points of the phase inversion temperature + 20 ° C. A region A surrounded by the solid line and the dotted line is a region where a one-phase W / O microemulsion to a fine W / O emulsion are generated.
In the present invention, a polymerization system is prepared by selecting the type and mixing ratio of the dispersion medium and the water-soluble ethylenically unsaturated monomer, and the phase inversion temperature of this system matches the thermal radical polymerization temperature (about 30 to 100 ° C.). By selecting such a surfactant, a water-swellable polymer in the form of a fine microgel can be produced in a certain optimum temperature range (phase inversion temperature + 20 ° C.). The thermal radical polymerization itself can be performed by a known method using a known radical polymerization initiator as long as the polymerization is performed in the A region. A photopolymerization initiator can also be used, but is not suitable for industrial mass production.
[0021]
In the production method of the present invention, a preferred surfactant is a nonionic surfactant having a large temperature dependence of phase inversion. There are no restrictions on the chemical species, and the electrical conductivity can be actually measured in the desired polymerization composition, or a three-component phase diagram of dispersion medium / surfactant / water-soluble ethylenically unsaturated monomer can be prepared. Thus, one or a combination of two or more surfactants suitable for the polymerization composition is determined.
Specific examples of preferable surfactants include polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene hexyl decyl ether, polyoxyethylene Ethylene isostearyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene behenyl ether, polyoxyethylene cholesteryl ether, polyoxyethylene hydrogenated castor oil, sorbitan fatty acid ester, mono fatty acid glycerin, tri fatty acid glycerin, polyglycerin fatty acid ester, isostearic acid poly Oxyethylene glycerin, polyisoethylene stearic acid polyoxyethylene glycerin, monosteary Polyoxyethylene glyceryl distearate, polyoxyethylene glyceryl, and the like tristearate polyoxyethylene Ruri glyceryl.
[0022]
The water-soluble ethylenically unsaturated monomer is preferably a combination of a nonionic monomer and an ionic monomer (anionic monomer or cationic monomer).
The nonionic monomer is preferably dialkylacrylamide.
The ionic monomer is preferably an anionic acrylamide derivative or a cationic acrylamide derivative.
Particularly preferred dialkylacrylamides are dimethylacrylamide and diethylacrylamide.
Particularly preferred ionic acrylamide derivatives are 2-acrylamide 2-methylpropanesulfonic acid and its salts.
A particularly preferred cationic acrylamide derivative is N, N, -dimethylaminopropylacrylamide methyl chloride.
The monomer composition ratio in the polymerization system of the nonionic monomer and the ionic monomer (the charge ratio of the polymerization system) is arbitrarily determined arbitrarily according to the monomer composition ratio of the target microgel. The monomer composition ratio of the microgel and the charging ratio to the polymerization system are almost the same. The charging ratio (molar ratio) of the polymerization system of the nonionic monomer and the ionic monomer is usually nonionic monomer: ionic monomer = 0.5: 9.5 to 9.5: 0.5, preferably 1. : 9 to 9: 1, more preferably 7: 3 to 9: 1. The optimum ratio is nonionic monomer: ionic monomer = 8: 2.
The water-swellable polymer of the present invention is polymerized by arbitrarily selecting the water-soluble ethylenically unsaturated monomer. In the production method of the present invention, it is particularly preferable that dimethylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid are used as water-soluble ethylenically unsaturated monomers, and the copolymer microgel is copolymerized from these monomers. A production method for polymerizing a water-swellable polymer. In the production method of the present invention, a crosslinking monomer is not required, and a water-swellable polymer having an excellent thickening effect by self-crosslinking can be obtained.
[0023]
As described above, the production method of the present invention is performed, for example, in the following steps to produce a water-swellable polymer.
(1) An arbitrary surfactant is mixed in a composition containing a water-soluble ethylenically unsaturated monomer aqueous solution in a dispersed phase and an organic solvent or oil as a dispersion medium, and a temperature at which the electric conductivity becomes 0 (inversion). Phase temperature).
(2) Any temperature within a range not exceeding 20 ° C. from this phase inversion temperature (preferably a temperature higher by 5 to 10 ° C. than the phase inversion temperature) can be controlled by any desired thermal radical polymerization temperature (preferably 30 ° C. The above-mentioned arbitrary surfactant (the kind or combination of two or more kinds) and the blending amount thereof are determined so that the temperature is 100 ° C. or less.
(3) In the polymerization composition determined as described above, thermal radical polymerization is carried out while maintaining the desired controllable thermal radical polymerization temperature. The thermal radical polymerization temperature may be maintained in a range not exceeding 20 ° C. from the phase inversion temperature, but it is preferably maintained at a temperature 5 to 10 ° C. higher than the phase inversion temperature.
(4) If the above-mentioned method does not achieve the desired thermal radical polymerization temperature at which the phase inversion temperature of the polymerization composition can be controlled, the organic solvent or oil content of the dispersion medium can be changed, or a water-soluble ethylenically unsaturated monomer. The composition of the aqueous solution (aqueous phase) and the organic solvent or oil (oil phase) is changed as appropriate, and the surfactant used in the polymerization composition and the blending amount thereof are determined by the above method.
[0024]
The aqueous dispersion of the water-swellable polymer obtained by the production method of the present invention has the following rheological properties (1) and (2).
The apparent viscosity of an aqueous dispersion of 0.5% (mass percentage) of the water-swellable polymer is 10000 mPas or more at a shear rate of 1.0 s-1.
The dynamic elastic modulus of an aqueous dispersion of 0.5% (mass percentage) of the water-swellable polymer has a strain of 1% or less and G ′> G ″ in the frequency range of 0.01 to 10 Hz.
The apparent viscosity of an aqueous dispersion of a water-swellable polymer is a viscosity at a measurement temperature of 25 ° C. and a shear rate of 1.0 s-1 using a cone plate rheometer (MCR-300 manufactured by Paar Physica). The dynamic elastic modulus is a value of storage elastic modulus (G ') and loss elastic modulus (G ") measured at a measurement temperature of 25 ° C, a strain of 1% or less, and a frequency range of 0.01 to 10 Hz using the same measuring apparatus. Means.
These physical property values can be measured not only by the above apparatus but also by a commercially available rheometer.
[0025]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.
[0026]
"Example 1"
40 g of dimethylacrylamide (manufactured by Kojin) and 9 g of 2-acrylamido-2-methylpropanesulfonic acid (manufactured by Sigma) are dissolved in 250 g of ion-exchanged water and adjusted to pH = 7.0 with sodium hydroxide. In a 1000 mL four-necked flask equipped with a reflux apparatus, n-hexane 250 g polyoxyethylene (3) oleyl ether (Emalex 503, manufactured by Nihon Emulsion) 8.2 g and polyoxyethylene (6) oleyl ether (Emalex 506, manufactured by Nihon Emulsion) ) Add 16.4g, mix and dissolve, and replace with N2. An aqueous monomer solution is added to the four-necked flask and gradually heated to 65-70 ° C. in an oil bath while stirring in an N 2 atmosphere.
The electrical conductivity of the polymerization composition is monitored with a tester, and the temperature at which the electrical conductivity sharply decreases and becomes substantially zero is defined as the phase inversion temperature (59 ° C.), so as not to exceed 20 ° C. from this temperature. The polymerization temperature is controlled at 65 ° C.
Next, after confirming that the polymerization composition is in a translucent state, 0.2 g of ammonium persulfate is added to the polymerization composition to start polymerization. A water-swellable polymer is produced by maintaining the polymerization system at the above temperature for 4 hours while stirring.
After completion of the polymerization, a large amount of acetone is added to the polymerization solution to precipitate a water-swellable polymer, and subsequently washed three times with acetone to remove residual monomers and surfactants. The precipitate was filtered and dried under reduced pressure to obtain a white powdery water-swelled polymer dried product. The yield was 96%. A 0.5% ion exchange aqueous dispersion of the obtained water-swellable polymer was prepared, and apparent viscosity and dynamic elastic modulus were measured.
The results of the apparent viscosity, the phase inversion temperature and the polymerization temperature are shown in Table 1, and the result of the dynamic elastic modulus is shown in FIG.
[0027]
"Example 2"
35 g of dimethylacrylamide (manufactured by Kojin) and 17.5 g of 2-acrylamido-2-methylpropanesulfonic acid (manufactured by Sigma) are dissolved in 250 g of ion-exchanged water and adjusted to pH = 7.0 with sodium hydroxide. In a 1000 mL four-necked flask equipped with a reflux apparatus, n-hexane 250 g polyoxyethylene (3) oleyl ether (Emalex 503, manufactured by Nihon Emulsion) 8.2 g and polyoxyethylene (6) oleyl ether (Emalex 506, manufactured by Nihon Emulsion) ) Add 16.4g, mix and dissolve, and replace with N2. An aqueous monomer solution is added to the four-necked flask and gradually heated to 65-70 ° C. in an oil bath while stirring in an N 2 atmosphere.
The electrical conductivity of the polymerization composition is monitored with a tester, and the temperature at which the electrical conductivity sharply decreases and becomes substantially zero is defined as the phase inversion temperature (60 ° C.), so that the temperature does not exceed 20 ° C. The polymerization temperature is controlled at 65 ° C.
Next, after confirming that the polymerization composition is in a translucent state, 0.2 g of ammonium persulfate is added to the polymerization composition to start polymerization. A water-swellable polymer is produced by maintaining the polymerization system at the above temperature for 4 hours while stirring.
After completion of the polymerization, a large amount of acetone is added to the polymerization solution to precipitate a water-swellable polymer, and subsequently washed three times with acetone to remove residual monomers and surfactants. The precipitate was filtered and dried under reduced pressure to obtain a white powdery water-swelled polymer dried product. The yield was 95%. A 0.5% ion exchange aqueous dispersion of the obtained water-swellable polymer was prepared, and apparent viscosity and dynamic elastic modulus were measured.
The results of apparent viscosity, phase inversion temperature and polymerization temperature are shown in Table 1, and the results of dynamic elastic modulus are shown in FIG.
[0028]
"Example 3"
30 g of dimethylacrylamide (manufactured by Kojin) and 26.7 g of 2-acrylamido-2-methylpropanesulfonic acid (manufactured by Sigma) are dissolved in 250 g of ion-exchanged water and adjusted to pH = 7.0 with sodium hydroxide. In a 1000 mL four-necked flask equipped with a reflux apparatus, n-hexane 250 g polyoxyethylene (3) oleyl ether (Emalex 503, manufactured by Nihon Emulsion) 8.2 g and polyoxyethylene (6) oleyl ether (Emalex 506, manufactured by Nihon Emulsion) ) Add 16.4g, mix and dissolve, and replace with N2. An aqueous monomer solution is added to the four-necked flask and gradually heated to 65-70 ° C. in an oil bath while stirring in an N 2 atmosphere.
The electrical conductivity of the polymerization composition is monitored with a tester, and the temperature at which the electrical conductivity sharply decreases and becomes substantially zero is defined as the phase inversion temperature (55 ° C.), so as not to exceed 20 ° C. from this temperature. The polymerization temperature is controlled at 68 ° C.
Next, after confirming that the polymerization composition is in a translucent state, 0.2 g of ammonium persulfate is added to the polymerization composition to start polymerization. A water-swellable polymer is produced by maintaining the polymerization system at the above temperature for 4 hours while stirring.
After completion of the polymerization, a large amount of acetone is added to the polymerization solution to precipitate a water-swellable polymer, and subsequently washed three times with acetone to remove residual monomers and surfactants. The precipitate was filtered and dried under reduced pressure to obtain a white powdery water-swelled polymer dried product. The yield was 95%. A 0.5% ion exchange aqueous dispersion of the obtained water-swellable polymer was prepared, and apparent viscosity and dynamic elastic modulus were measured.
The results of the apparent viscosity, the phase inversion temperature and the polymerization temperature are shown in Table 1, and the results of the dynamic elastic modulus are shown in FIG.
[0029]
"Comparative example: Example of polymerization in a range deviating from the A region"
35 g of dimethylacrylamide (manufactured by Kojin) and 17.5 g of 2-acrylamido-2-methylpropanesulfonic acid (manufactured by Sigma) are dissolved in 250 g of ion-exchanged water and adjusted to pH = 7.0 with sodium hydroxide. In a 1000 mL four-necked flask equipped with a reflux apparatus, 250 g of n-hexane, 16.4 g of polyoxyethylene (3) oleyl ether (Emalex 503, manufactured by Nippon Emulsion) and polyoxyethylene (6) oleyl ether (Emalex 506, Japan) Emulsified (8.2g), mixed and dissolved to replace N2. An aqueous monomer solution is added to this four-necked flask and gradually heated to 65-70 ° C. in an oil bath while stirring in an N 2 atmosphere.
The electrical conductivity of this polymerization composition is monitored with a tester, and the temperature at which the electrical conductivity sharply decreases and becomes substantially zero is defined as the phase inversion temperature (23 ° C.), so that the temperature exceeds 20 ° C. from this temperature. The polymerization temperature is controlled at 66 ° C.
Next, 0.2 g of ammonium persulfate is added to the polymerization composition to initiate the polymerization. A water-swellable polymer is produced by maintaining the polymerization system at the above temperature for 4 hours while stirring. After completion of the polymerization, a large amount of acetone is added to the polymerization solution to precipitate a water-swellable polymer, and subsequently washed three times with acetone to remove residual monomers and surfactants. The precipitate was filtered and dried under reduced pressure to obtain a white powdery water-swellable polymer impression product. The yield was 96%. A 0.5% ion exchange water dispersion of the obtained water-swellable polymer was prepared and the apparent viscosity was measured.
The results of apparent viscosity, phase inversion temperature and polymerization temperature are shown in Table 1.
[0030]
[Table 1]
(2) Temperature at which the electrical conductivity changed to zero
(3) Average temperature of the polymerization composition during polymerization [0031]
【The invention's effect】
According to the production method of the present invention, a water-swellable polymer having an excellent thickening effect can be easily produced.
The water-swellable polymer radically polymerized by the production method of the present invention takes the form of a microgel and is obtained in a powder state. When used for a thickener application, like a polymer gel obtained by a conventional production method, It has the advantage that there is no need to grind.
[Brief description of the drawings]
FIG. 1 is a phase diagram of a three-component polymerization composition of hexane (O) / surfactant / water-soluble ethylene monomer aqueous solution (W).
2 is a graph showing the dynamic elastic modulus of an aqueous dispersion of a water-swellable polymer obtained in Example 1. FIG.
3 is a graph showing the dynamic elastic modulus of an aqueous dispersion of a water-swellable polymer obtained in Example 2. FIG.
4 is a graph showing the dynamic elastic modulus of an aqueous dispersion of a water-swellable polymer obtained in Example 3. FIG.
Claims (6)
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002209587A JP3850347B2 (en) | 2002-07-18 | 2002-07-18 | Method for producing water-swellable polymer |
| TW092112797A TWI287571B (en) | 2002-05-14 | 2003-05-12 | Thickener, cosmetic preparation containing the same, and process for producing the same |
| US10/513,824 US20050175564A1 (en) | 2002-05-14 | 2003-05-12 | Tickener, cosmetic preparation containing the same, and process for producing the same |
| KR1020047012746A KR100970123B1 (en) | 2002-05-14 | 2003-05-12 | Thickener, cosmetic preparation containing the same, and process for producing the same |
| PCT/JP2003/005863 WO2003095583A1 (en) | 2002-05-14 | 2003-05-12 | Thickener, cosmetic preparation containing the same, and process for producing the same |
| CN03810887A CN100579507C (en) | 2002-05-14 | 2003-05-12 | Tickener, cosmetic preparation containing the same, and process for producing the same |
| EP03723318.6A EP1505139B2 (en) | 2002-05-14 | 2003-05-12 | Thickener, cosmetic preparation containing the same, and process for producing the same |
| US12/576,438 US7927615B2 (en) | 2002-05-14 | 2009-10-09 | Thickener, cosmetic preparation containing the same, and process for producing the same |
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|---|---|---|---|
| JP2002209587A JP3850347B2 (en) | 2002-07-18 | 2002-07-18 | Method for producing water-swellable polymer |
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| JP2004051739A JP2004051739A (en) | 2004-02-19 |
| JP3850347B2 true JP3850347B2 (en) | 2006-11-29 |
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