JP4815710B2 - Water-absorbing material and blood-absorbing article using the same - Google Patents

Description

【００２０】
（但し、一般式［１］中、Ｒ₁はアミノ基、エポキシ基、カルボキシル基、カルボジイミド基、オキサゾリン基、イミノ基、イソシアネート基からなる群より選ばれる少なくとも１個の基、−Ｑ−は炭素原子数１〜１０のアルキレン基、Ｒ₂は水素、又は炭素原子数１〜４のアルキル基である。）
【００２１】
前記一般式［１］で表される化合物としては、例えば、グリシジルアクリレート、グリシジルメタクリレート、アクリル酸、メタクリル酸、２−メタクロイルオキシエチルイソシアネート、２−イソシアネートメチルアクリレート等が挙げられるが、これらに限定されない。
【００２２】
本発明で使用するエチレン性不飽和化合物（Ｂ）は、水溶性又は水混和性であれば何れのものも使用出来、その一例を挙げれば、（メタ）アクリル酸及び／又はそのアルカリ金属塩、アンモニウム塩、２−（メタ）アクリルアミド−２−メチルスルホン酸及び／又はそのアルカリ金属塩等のイオン性モノマー；（メタ）アクリルアミド、Ｎ，Ｎ−ジメチルアクリルアミド、２−ヒドロキシエチル（メタ）アクリレート、Ｎ−メチロール（メタ）アクリルアミド等の非イオン性モノマー；ジエチルアミノエチル（メタ）アクリレート、ジメチルアミノプロピル（メタ）アクリレート等のアミノ基含有不飽和モノマーやそれらの四級化物等を挙げることが出来、これらの群から選ばれる一種又は二種以上を用いることが出来る。尚、ここで「（メタ）アクリル」という用語は、「アクリル」及び「メタクリル」の何れをも意味するものとする。これらの中で好ましくは、（メタ）アクリル酸及び／又はそのアルカリ金属塩、アルカリ土類金属塩、アンモニウム塩、（メタ）アクリルアミドが挙げられ、アルカリ金属塩としてはナトリウム塩、カリウム塩、リチウム塩、ルビジウム塩等が、またアルカリ土類金属塩としては、カルシウム塩、マグネシウム塩等が挙げられる。
【００２３】
本発明で使用するエチレン性不飽和化合物（Ｂ）は、水溶性又は水混和性のエチレン性不飽和化合物に、架橋剤（Ｃ）として、２個以上のエチレン性不飽和基を有する多官能エチレン性不飽和化合物、もしくは２個以上の反応性基を有する化合物を併用して用いられることがより好ましい。
【００２４】
多官能エチレン性不飽和化合物としては、エチレン性不飽和基を２個以上有するエチレン性不飽和化合物であれば基本的にはすべての化合物を用いることが可能であり、例えば、Ｎ，Ｎ’−メチレンビス（メタ）アクリルアミド、（ポリ）エチレングリコールジ（メタ）アクリレート、（ポリ）プロピレングリコールジ（メタ）アクリレート、トリメチロールプロパントリ（メタ）アクリレート、トリメチロールプロパンジ（メタ）アクリレート、グリセリントリ（メタ）アクリレート、グリセリンアクリレートメタアクリレート、エチレンオキサイド変性トリメチロールプロパントリ（メタ）アクリレート、ペンタエリスリトールテトラ（メタ）アクリレート、ジペンタエリスリトールヘキサ（メタ）アクリレート等を挙げることが出来る。
【００２５】
また、２個以上の反応性基を有する化合物としては、例えば、エチレングリコール、ジエチレングリコール、トリエチレングリコール、ポリエチレングリコール、グリセリン、ポリグリセリン、プロピレングルコール、１，４−ブタンジオール、１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルアルコール、ジエタノールアミン、トリジエタノールアミン、ポリプロピレングリコール、ポリビニルアルコール、ペンタエリスリトール、ソルビット、ソルビタン、グルコース、マンニット、マンニタン、ショ糖、ブドウ糖等の多価アルコール；エチレングリコールジグリシジルエーテル、ポリエチレングリコールジグリシジルエーテル、グリセリントリグリシジルエーテル等のポリグリシジルエーテル；エピクロロヒドリン、α−メチルクロルヒドリン等のハロエポキシ化合物；グルタールアルデヒド、グリオキザール等のポリアルデヒド；エチレンジアミン等のポリアミン類；水酸化カルシウム、塩化カルシウム、炭酸カルシウム、酸化カルシウム、塩化硼砂マグネシウム、酸化マグネシウム、塩化アルミニウム、塩化亜鉛および塩化ニッケル等の周期律表２Ａ族、３Ｂ族、８族の金属の水酸化物、ハロゲン化物、炭酸塩、酸化物、硼砂等の硼酸塩、アルミニウムイソプロピラート等の多価金属化合物等が挙げられる。これらの、２個以上のエチレン性不飽和基を有する多官能エチレン性不飽和化合物、もしくは２個以上の反応性基を有する化合物は１種又は２種以上を、反応性を考慮した上で用いることが出来る。
【００２６】
また、本発明で使用する多糖類としては、例えば、デンプン、セルロース、アルギン酸等が挙げられる。デンプンとしては、一般に天然又は植物起源の、アミロース及び／又はアミロペンチンよりなるデンプンやデンプン含有物及びそれらの変性体の全てを包含する。デンプンとしては、例えば、馬鈴薯澱粉、玉蜀黍澱粉、小麦澱粉、タピオカ澱粉、米澱粉、甘藷澱粉、サゴ澱粉、ワキシーコンス、ハイアミロースコンス、小麦粉、米粉等が挙げられる。また、変性澱粉としては、澱粉にモノマー、例えば、アクリル酸エステル、メタクリル酸エステル、オレフィン、スチレン等をグラフト共重合されたものや、脂肪酸を反応させたもの、その他、これらをデキストリン化、酸化、酸処理、アルファー化処理、エーテル化、エステル化、架橋化したものも用いることが出来る。また、水分を含む澱粉をそのガラス転移点温度及び融解温度より高い温度に加熱した構造変性澱粉（ＥＰ０３２７５０５ Ａ２）が包含される。更に、グアーガム、キチン、キトサン、セルロース、アルギン酸、寒天等の多糖類も使用することが出来る。セルロースとしては、例えば、木材、葉、茎、ジン皮、種子毛などから得られるセルロース；アルキルエーテル化セルロース、有機酸エステル化セルロース、カルボキシメチル化セルロース、酸化セルロース、ヒドロキシアルキルエーテル化セルロースなどの加工セルロースが挙げられる。
【００２７】
本発明に係るポリアミノ酸又はその塩を含む吸水性樹脂であって、該吸水性樹脂の粒子同士が接合した状態である吸水性材料は、分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）とエチレン性不飽和化合物（Ｂ）と、必要に応じ多糖類とを架橋剤（Ｃ）の存在下、例えば、双椀型ニーダー中で攪拌しながら重合する方法、容器中で注型重合する方法、駆動するベルト上で連続的に静置重合する方法、逆相懸濁重合法等既知のラジカル重合開始剤を用いた重合方法により得られた重合体粒子に表面架橋処理を行うことにより製造することが出来る。これら方法の中でも、容易に重合体粒子を得られる点で、界面活性剤（Ｄ）の存在下でラジカル重合開始剤を用いて不活性溶媒中で油中水滴型の逆相懸濁重合法で得られた重合体粒子に表面架橋処理を行い製造することが好ましい。
【００２８】
本発明で使用するラジカル重合開始剤としては、例えば、無機過酸化物（過酸化水素、過硫酸アンモニウム、過硫酸カリウム、過硫酸ナトリウム等）、有機過酸化物（過酸化ベンゾイル、ジ−ｔ−ブチルパーオキサイド、クメンヒドロキシパーオキサイド、コハク酸パーオキサイド、ジ（２−エトキシエチル）パーオキシジカーボネート等）、アゾ化合物（アゾビスイソブチルニトリル、アゾビスシアノ吉草酸、２，２’−アゾビス（２−アミノプロパン）ハイドロクロライド等）及びレドックス触媒（アルカリ金属の亜硫酸塩若しくは重亜硫酸塩、亜硫酸アンモニウム、重亜硫酸アンモニウム、アスコルビン酸等の還元剤とアルカリ金属の過硫酸塩、過硫酸アンモニウム、過酸化物等の酸化剤の組み合わせよりなるもの）が挙げられる。
【００２９】
逆相懸濁重合法により、含水ゲル、過剰の界面活性剤及び不活性溶媒からなるスラリー状の混合物が得られる。重合後のスラリーは公知の手法により、例えば、直接脱水或いは不活性溶媒との共沸脱水を経て、乾燥、篩等を経て吸水性樹脂を得ることが出来る。
【００３０】
この場合、使用される界面活性剤（Ｄ）は、疎水性溶媒に可溶性又は親和性であり、基本的に油中水滴型乳化系を作るものであれば何れのものも使用出来る。このような界面活性剤としては、一般的にはＨＬＢ(Hydrophile-Lipophile-Balance)が好ましくは１〜９の範囲であり、より好ましくは２〜７の範囲の非イオン系及び／又はアニオン系である。
【００３１】
本発明で使用する界面活性剤（Ｄ）の具体例としては、例えば、ソルビタン脂肪酸エステル、ポリオキシソルビタン脂肪酸エステル、ショ糖脂肪酸エステル、ポリグリセリン脂肪酸エステル、ポリオキシエチレンアルキルフェニルエーテル、エチルセルロース、エチルヒドロキシエチルセルロース、酸化ポリエチレン、無水マレイン化ポリエチレン、無水マレイン化ポリブタジエン、無水マレイン化エチレン・プロピレン・ジエン・ターポリマー、α−オレフインと無水マレイン酸の共重合体又はその誘導体ポリオキシエチレンアルキルエーテル燐酸等が挙げられる。これら界面活性剤は２種以上を適宜併用することも可能である。
【００３２】
本発明で使用する界面活性剤（Ｄ）の使用量は、不活性溶媒に対して、好ましくは０．０５〜１０重量％、より好ましくは０．１〜１重量％の範囲である。界面活性剤（Ｄ）の使用量がかかる範囲であれば、安定した逆相懸濁状態を保つことが出来、また最終的に得られた吸水性樹脂において、本発明の目的とする血液吸収特性をもたらすことが出来る。
【００３３】
また、本発明で使用する不活性溶媒とは、水に溶け難い疎水性溶媒であり、重合反応に対して不活性であれば如何なるものも使用可能であり、特に限定はない。前記不活性溶媒としては、例えば、ｎ−ペンタン、ｎ−ヘキサン、ｎ−ヘプタン、ｎ−オクタン等の脂肪族炭化水素；シクロヘキサン、メチルシクロヘキサン等の脂環状炭化水素；ベンゼン、トルエン、キシレン等の芳香族炭化水素等が挙げられる。これら中では、ｎ−ヘキサン、ｎ−ヘプタン、シクロヘキサンが好ましい。
【００３４】
上記不活性溶媒の使用量は、第１段目の反応に使用されるエチレン性不飽和化合物（Ｂ）の水溶液に対して、０．５〜１０重量倍の範囲が好ましい。
【００３５】
本発明で用いる逆相懸濁重合法のより具体的な実施方法としては、例えば、予め使用するエチレン性不飽和化合物（Ｂ）の内、必要に応じ１種又は２種以上を中和したエチレン性不飽和化合物水溶液に、架橋剤（Ｃ）、ラジカル重合開始剤、及び必要に応じてチオール類、チオール酸類、第２級アルコール類、アミン類、次亜燐酸塩類等の水溶性連鎖移動剤を添加溶解したエチレン性不飽和化合物（Ｂ）の水溶液を調製し、窒素等の不活性ガスを導入して脱気を行う。一方、重合装置内で界面活性剤（Ｄ）を不活性溶媒中に入れ必要ならば若干加温し溶解せしめ、窒素等不活性ガスを導入し、脱気を行う。この中に上記エチレン性不飽和化合物（Ｂ）の水溶液を注入し、攪拌下、昇温を開始する。この間に反応系の水溶液は微細な液滴となって不活性溶媒中に分散しながら懸濁する。昇温とともにやがて発熱が起こり重合が開始する。
【００３６】
本発明において、分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）の添加方法としては、特に制限はないが、▲１▼予め加水分解した分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）の水溶液をエチレン性不飽和化合物（Ｂ）の水溶液と予め混合することにより行う方法；▲２▼エチレン性不飽和化合物（Ｂ）の水溶液と同時に注入する方法；▲３▼昇温時に注入する方法；▲４▼発熱が起こり重合が開始した後で注入する方法等、何れでもよいが、この中で系の安定性がより保持できる点で、▲４▼発熱が起こり重合が開始した後で注入する方法が好ましい。発熱が起こり重合が開始した後で分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）の水溶液を添加する場合は、水溶液をそのまま添加してもよい。
【００３７】
尚、界面活性剤を溶解させた不活性溶媒を分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）の水溶液に加え、攪拌分散させた後に重合液に添加する方が、粒子同士が凝集を起こすこともなく、重合安定性が良好になることからより好ましい。この時使用する界面活性剤は前記の逆相懸濁重合法に使用する界面活性剤（Ｄ）の何れのものを１種又は２種以上を混合して用いてもよいが、好ましくは先にモノマーの重合に用いている界面活性剤よりもＨＬＢ値の高い界面活性剤を用いる方がより好ましい。このような界面活性剤としては具体的には、一般的にはＨＬＢ値が４〜１８の非イオン系及び／又はアニオン系界面活性剤が好ましい。
【００３８】
発熱後の注入の時期は、特に限定しないが、好ましくは発熱直後から３時間経過後までの間、より好ましくは発熱直後から２時間後までの間である。この時期で注入を行うことにより、分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）の水溶液が分離することなく、反応系中で形成されつつある吸水性樹脂の粒子内に取り込まれることが出来るので好ましい。
【００３９】
また、予め使用するエチレン性不飽和化合物（Ｂ）の内、必要に応じ１種又は２種以上を中和したエチレン性不飽和化合物水溶液に、架橋剤、ラジカル重合開始剤、及び必要に応じてチオール類、チオール酸類、第２級アルコール類、アミン類、次亜燐酸塩類等の水溶性連鎖移動剤を添加溶解したエチレン性不飽和化合物の水溶液を逐次供給することも出来、逐次供給することにより、接合した状態の吸水性樹脂を容易に得ることことが出来る。逐次供給する方法は、特に限定しないが、例えば、▲１▼上記エチレン性不飽和化合物（Ｂ）の水溶液を不活性溶媒の中に連続的に滴下しながら逐次重合させる方法；▲２▼エチレン性不飽和化合物（Ｂ）の水溶液を不活性溶媒の中に断続的に滴下しながら逐次重合させる方法；▲３▼上記エチレン性不飽和化合物（Ｂ）の水溶液を予め一部の不活性溶媒と混合又は分散して得られる混合／分散溶液を不活性溶媒の中に滴下しながら重合させる方法等がある。
【００４０】
この時、分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）の添加方法としては、特に制限はないが、予め加水分解した分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）の水溶液を、▲１▼エチレン性不飽和化合物（Ｂ）の水溶液と予め混合し滴下する方法；▲２▼エチレン性不飽和化合物（Ｂ）の水溶液と同時に滴下する方法；▲３▼エチレン性不飽和化合物（Ｂ）の水溶液の滴下終了後、一括注入又は続けて滴下する方法等が挙げられる。この時、安定に重合を行うために先記したように、界面活性剤を溶解せしめた不活性溶媒を分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）の水溶液に加え、攪拌分散させた後に重合液に添加してもよい。
【００４１】
本発明における不活性溶媒と水溶液全体の混合割合は、通常、好ましくは１０／１〜０．５／１重量比、より好ましくは５／１〜０．８／１重量比の範囲である。不活性溶媒とエチレン性不飽和化合物（Ｂ）の水溶液の割合が上記重量比の範囲内であるなら、重合安定性も良好であり、重合熱の徐熱も容易となり、生産性も上がるので好ましい。
【００４２】
重合開始後、発熱の状態によって適宜冷却もしくは加熱を行う。重合反応温度は、特に限定はしないが、通常、好ましくは６０〜１００℃、より好ましくは６０〜８０℃の範囲である。
【００４３】
又、撹拌条件は、反応時の撹拌回転数は用いる撹拌翼の種類、重合反応槽のスケールによってその絶対値は異なってくるので一義的には示すことが出来ないが、攪拌速度が重合体粒子の粒径に影響すること、更に接合後の平均粒径を１００μｍ〜１０００μｍの範囲に制御することが好ましいことから、撹拌翼の種類に応じて攪拌動力を制御することが好ましく、また攪拌速度は適宜選択出来るが通常５０〜１０００ｒｐｍの範囲であることが好ましい。この範囲の撹拌回転数の範囲で、撹拌翼の種類、攪拌動力を適宜選択することにより、本発明の目的とする血液に対する親和性と吸収特性を兼ね備えた吸水性樹脂の重合体粒子を得ることが出来る。
【００４４】
本発明に係る吸水性樹脂は、分子内に少なくとも１つのエチレン性不飽和結合を有する無水ポリ酸性アミノ酸（Ａ）とエチレン性不飽和化合物（Ｂ）とを反応させることにより得られる吸水性樹脂の表面近傍を、表面架橋剤（Ｅ）を用いて架橋反応させることにより、重合体粒子同士の接合をより一層緊密にすることが出来、その結果血液に対する吸収特性を一層高めることが可能となる。更に、表面架橋により、逆相懸濁重合で得た重合体粒子同士の接合状態を一層高めることが出来ることから、平均粒径を１００μｍ〜１０００μｍの範囲に制御することが可能になる。
【００４５】
本発明で使用する表面架橋剤（Ｅ）としては、吸水性樹脂の表面近傍の官能基と反応可能な２個以上の官能基を有するものであり、且つ血液吸収用物品等に使用した場合に人体に対して安全性の高いものが好ましい。そのような化合物としては、例えば、ポリアミンやポリグリシジルエーテル等の２個以上のカルボキシル基（カルボキシレート基）と反応し得る反応性基を有する化合物、及びγ−グリシドキシプロピルトリメトキシシラン、γ−グリシドキシプロピルメチルジエトキシシラン、Ｎ−β−（アミノエチル）−γ−アミノプロピルトリメトキシシラン、γ−メルカプトプロピルトリメトキシシランといったシランカプリング剤を、必要に応じシラノール縮合触媒として知られているジブチル錫ジラウリレート、ジブチル錫ジアセテート、ジブチル錫ジオクトエート等と共に、用いることが出来る他、グリシジルメタクリレート等の反応性基を有するエチレン性不飽和化合物を必要に応じラジカル重合開始剤と共に用いることが可能である。
【００４６】
本発明における表面架橋処理は、逆相懸濁重合後に膨潤したビーズ状の粒子から、共沸脱水又は加熱等の適当な方法により直接脱水することにより、所定の含水率まで乾燥せしめた粉末状のポリマーと表面架橋剤（Ｅ）を混合することにより行うことが出来る。この時、表面架橋剤（Ｅ）を均一に混合させるために、水及び親水性溶媒を共に使用することが好ましく、表面架橋剤（Ｅ）に水及び親水性溶媒をポリマー１００重量部に対して、水が５０重量部以下、及び親水性溶媒を６０重量部以下、混合し用いてもよい。
【００４７】
本発明で使用する親水性溶媒としては、例えば、メタノール、エタノール、ｎ−プロパノール、イソプロパノール、ｎ−ブタノール、およびイソブタノールのような低級アルコール類、アセトン、およびメチルエチルケトンのようなケトン類、ジオキサン、テトラヒドロフラン、およびジエチルエーテルのようなエーテル類、Ｎ，Ｎ−ジメチルホルムアミドおよびＮ，Ｎ−ジエチルホルムアミドのようなアミド類およびジメチルスルホキシドのようなスルホキシド類等が挙げられる。
【００４８】
ポリマーと表面架橋剤（Ｅ）の混合方法は特に制限されず、通常の混合機を用いることが出来る。混合装置としては、例えば、円筒型混合機、二重壁円錐型混合機、高速攪拌型混合機、Ｖ字型混合機、リボン型混合機、スクリュー型混合機、流動型炉ロータリーデスク型混合機、気流型混合機、双腕型ニーダー、内部混合機、粉砕型ニーダー、回転式混合機、スクリュー型押出機等の混合装置でポリマーを攪拌しながら表面架橋剤を添加することが好ましく、表面架橋剤が均一に混合されるために噴霧されることがより好ましい。
【００４９】
表面架橋の加熱処理時間は、加熱温度により適宜選択されるが、熱劣化を起こさずに吸水性能の高い吸水性樹脂が得られることから、通常、好ましくは、６０℃〜３００℃の温度で、５分から１００時間以下であることが好ましい。
【００５０】
加熱処理装置としては、特に限定はしないが、通常、乾燥機又は加熱炉が用いられ、例えば、溝型混合乾燥機、ロータリー乾燥機、ディスク乾燥機、流動層乾燥機、気流型乾燥機、赤外線乾燥機、減圧乾燥機等が挙げられる。
【００５１】
本発明に係る吸水性材料は、特に血液に対して優れた吸収特性を示すものであるので、該吸水性材料を含むことを特徴とする血液吸収用物品としては、例えば、生理用ナプキン、タンポン、医療用血液吸収シート、ドリップ吸収剤、創傷保護材、創傷治癒材、手術用廃液処理剤等々の血液吸収特性が要求される物品が列記出来る。また、血液と同様にタンパク質を含む水、例えば、牛乳、母乳、おりもの等に対しても優れた吸収特性を示す他、従来の吸水性材料と同様の尿、海水、セメント水、土壌水、肥料含有水、雨水、排水等に対しても優れた吸収特性を有すため、その適用分野は広範囲である。
【００５２】
【実施例】
以下、本発明を実施例と比較例により、一層、具体的に説明する。以下において、％は、特にことわりのない限り、全て重量基準であるものとする。尚、材料の諸性質は以下に概略を示した方法で測定した。また、実施例１〜３及び比較例１、比較例２の仕込組成を表１にまとめた。
【００５３】
［血液吸引量の測定方法］
内径９５ｍｍのシャーレ中の馬脱繊血（株式会社日本生物材料センターより入手）２０ｍｌに浸した１５枚重ねのトイレットペーパー（河村製紙(株)製、シルバースワン）の面積５５ｍｍ×７５ｍｍの紙面上に、樹脂試料１ｇを加え、１０分間吸液させた後、試料の膨潤ゲルを採取してその重量を測定した。吸液後の膨潤ゲルの重量ｂ(g)を、吸液前の樹脂試料の重量ａ(g)で除して、血液吸引量ｂ／ａを算出した。
【００５４】
［血液吸収速度、及び、血液に対する親和性の測定方法］
内径７０ｍｍのシャーレ中に樹脂試料０．５ｇを均一に散布し、次いで、馬脱繊血２．５ｍｌを加えた時、血液が樹脂中に吸収されるまでの時間を血液吸収速度とした。また、この時の樹脂試料と血液の親和性を目視で観察し、血液が殆ど樹脂全体に浸透する場合を「親和性有り」、血液を散布した際に、血液が樹脂を押しのけたり、上部に乗ったまま殆ど浸透しない場合を「親和性がない」と判定した。
【００５５】
《参考例》ポリこはく酸イミドの製造例
攪拌装置、温度計、還流装置、窒素ガス吹き込み装置を装着した１Ｌの４ツ口フラスコに、無水マレイン酸９６ｇ、イオン交換水５０ｇを加えた。５５℃に加温し無水マレイン酸を溶解させた後、一旦冷却し無水マレイン酸のスラリーを得た。再び系内を加温し、５５℃になったところで、２８％アンモニア水６０．８ｇを添加した。その後、系内の温度を８０℃に加温した。３時間反応させた後、得られた水溶液を乾燥し反応中間体を得た。２Ｌのナスフラスコに反応中間体１００ｇおよび８５％燐酸１０ｇを仕込み、エバポレーターを用い、オイルバス浴温２００℃、減圧下、４時間反応させた。得られた生成物を水およびメタノールで数回洗浄した。得られたポリこはく酸イミドをＧＰＣで測定した結果、重量平均分子量は３０００であった。
【００５６】
《実施例１》
攪拌装置、温度計、還流装置、窒素ガス吹き込み装置を装着した５００ｍｌの４ツ口フラスコに、水酸化ナトリウム２０．６ｇを溶解させた水溶液７５ｇを加えた後、参考例１で得たポリこはく酸イミドの粉末５０ｇを添加することによりポリこはく酸イミドの水溶液を得た。次いで、温度を９０℃に昇温後、グリシジルメタクリレート５．０ｇを加え、反応を１時間行うことにより、メタクリル基を導入したポリこはく酸イミドの加水分解物を含有する水溶液を得た。１００ｍｌ三角フラスコに、ＨＬＢ＝１６のショ糖エステル（第一工業製薬株式会社製 ＤＫエステルＦ−１６０）０．７５ｇを秤量し、シクロヘキサン２０ｇを加え、５０℃に昇温して溶解した。これに上述の操作で得られた水溶液７．８ｇを加えて攪拌することによりメタクリル基を導入したポリこはく酸イミドの加水分解物水溶液の分散溶液を得た。
【００５７】
これとは別に、攪拌装置、温度計、還流装置、窒素ガス吹き込み装置を装着した５００ｍｌの４ツ口フラスコに、シクロヘキサン１６４ｇを加え、これにＨＬＢ＝９のショ糖エステル（第一工業製薬株式会社製 ＤＫエステルＦ−９０）０．７５ｇを添加して撹拌しながら５０℃に昇温して溶解した。その後、フラスコの内容物を３０℃に冷却した。一方、５００ｍｌの三角フラスコにアクリル酸３０ｇを加え、外部より冷却しつつ水酸化ナトリウム８．３ｇを溶解した水酸化ナトリウム水溶液８６．５ｇを滴下してアクリル酸の５０モル％を中和した。この液にＮ，Ｎ’−メチレンビスアクリルアミド２３．４ｍｇを添加し、更に過硫酸アンモニウム０．０５ｇを加えて溶解した。次に、上述のようにして得られた、重合開始剤および架橋剤を含有するアクリル酸塩水溶液を上述の円筒型丸底フラスコの内容物中に加え、界面活性剤を含むシクロヘキサン溶液に分散させると共に系内を窒素で充分に置換した。その後、加熱昇温し、重合反応を開始した。暫くした後発熱を開始し、発熱がピークに達した５分後に、先に得られたメタクリル基を導入したポリこはく酸イミドの加水分解物水溶液の分散溶液を一括添加した。以後６０〜６５℃で３時間保持した。尚、攪拌は３００ｒｐｍで行った。反応終了後、デカンテーションでシクロヘキサン相を分離し、続いて湿潤ポリマーから減圧乾燥により水を除去し、重合体粉末を得た。
【００５８】
５００ｍｌフラスコに得られた重合体粒子３０ｇを秤量し、そこへアセトン１．２ｇ、イオン交換水２．１ｇ、グリシジルメタクリレート０．０９ｇ、過硫酸アンモニウム０．０９ｇからなる混合溶液と、親水性シリカ（日本アエロジル株式会社製、２００ＣＦ）０．３ｇを均一散布した。湿潤ポリマーを１０８℃で１時間減圧乾燥することにより吸水性樹脂の表面架橋処理を行った。得られた吸水性樹脂の顕微鏡観察を行ったところ、図１に示すように球形の樹脂粒子が接合した状態を呈していた。本発明の吸水性材料の特性評価結果を表２に示す。実施例１で得た吸水性材料は、表２に示すように血液吸引能力（吸引量、吸収速度）に優れ、血液に対して親和性を有することが判る。
【００５９】
《実施例２》
５００ｍｌフラスコに実施例１と同様の操作により得られた重合体粒子３０ｇを秤量し、そこへアセトン１．２ｇ、イオン交換水２．１ｇ、グリシジルメタクリレート０．０９ｇ、過硫酸アンモニウム０．０９ｇからなる混合溶液と、親水性シリカ（日本アエロジル株式会社製、２００ＣＦ）０．３ｇを均一散布した。湿潤ポリマーを１８０℃で１時間減圧乾燥することにより吸水性樹脂の表面架橋処理を行った。得られた吸水性樹脂の顕微鏡観察を行ったところ、球形の樹脂粒子が接合した状態を呈していた。本発明の吸水性材料の特性評価結果を表２に示す。実施例２で得た吸水性材料は、表２に示すように血液吸引能力（吸引量、吸収速度）に優れ、血液に対して親和性を有することが判る。
【００６０】
《実施例３》
アクリル酸３０ｇを加え、外部より冷却しつつ水酸化リチウム・１水和物８．７ｇを溶解した水酸化リチウム水溶液８１．５ｇを滴下してアクリル酸の５０モル％を中和した以外は実施例１と同様の操作により、重合体粉末を得た。５００ｍｌフラスコに得られた重合体粒子３０ｇを秤量し、実施例２と同様の操作により吸水性樹脂の表面架橋処理を行った。得られた吸水性樹脂の顕微鏡観察を行ったところ球形の樹脂粒子が接合した状態を呈していた。本発明の吸水性材料の特性評価結果を表２に示す。実施例３で得た吸水性材料は、表２に示すように血液吸引能力（吸引量、吸収速度）に優れ、血液に対して親和性を有することが判る。
【００６１】
《比較例１》
アクリル酸３０ｇを加え、外部より冷却しつつ水酸化ナトリウム８．３ｇを溶解した水酸化ナトリウム水溶液８４．７ｇを滴下してアクリル酸の５０モル％を中和し、この液にＮ，Ｎ’−メチレンビスアクリルアミド２３．４ｍｇを添加し、更に過硫酸アンモニウム０．０５ｇを加えて溶解した。次に、上述のようにして得られた、重合開始剤および架橋剤を含有するアクリル酸塩水溶液を上述の円筒型丸底フラスコの内容物中に加え、界面活性剤を含むシクロヘキサン溶液に分散させると共に系内を窒素で充分に置換した。その後、加熱昇温し、重合反応を開始し、以後６０〜６５℃で３時間保持した。尚、攪拌は３００ｒｐｍで行った。反応終了後、デカンテーションでシクロヘキサン相を分離し、続いて湿潤ポリマーから減圧乾燥により水を除去し、重合体粉末を得た。
【００６２】
５００ｍｌフラスコに得られた重合体粒子３０ｇを秤量し、実施例１と同様の操作により表面架橋処理を行った。得られた吸水性樹脂の顕微鏡観察を行ったところ、図２に示すように球形の樹脂粒子は殆ど接合した状態ではなかった。ここで得られた吸水性材料の特性評価結果を表２に示す。
【００６３】
《比較例２》
アクリル酸３０ｇを加え、外部より冷却しつつ水酸化カリウム１３．８ｇを溶解した水酸化ナトリウム水溶液９０．３ｇを滴下してアクリル酸の５０モル％を中和した以外は比較例１と同様の操作により、吸水性樹脂の粉末を得た。得られた吸水性材料の特性評価結果を表２に示す。
【００６４】
【表１】

【００６５】
表１中の略称の物質名は以下の通りである。
ＧＭＡ ：グリシジルメタクリレート
ＭＢＡＡ：Ｎ，Ｎ−メチレンビスアクリルアミド
ＡＰＳ ：過硫酸アンモニウム
【００６６】
【表２】

【００６７】
【発明の効果】
本発明によると、ポリアミノ酸又はその塩を含む吸水性樹脂であって、該吸水性樹脂の粒子同士が接合した状態であることを特徴とする吸水性材料により、特に血液の吸収特性（吸引量、吸収速度、親和性など）を改善することが出来、血液成分により吸収特性が著しく低下することのない吸水性材料、及び血液吸収用物品を提供出来る。
【図面の簡単な説明】
【図１】 図１は、実施例１で得た本発明の吸水性材料の顕微鏡写真である。図１に示すように球形の樹脂粒子が接合した状態であることが判る。
【図２】 図２は、比較例１で得た吸水性材料の顕微鏡写真である。図２に示すように球形の樹脂粒子は殆ど接合していないことが判る。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel and useful water-absorbing material and a blood-absorbing article using the same. More specifically, the present invention relates to a water-absorbing material having improved blood absorption characteristics, and a blood-absorbing article using the water-absorbing material.
[0002]
[Prior art]
Conventionally, as a blood absorbing article such as a panty liner or sanitary napkin, a liquid-permeable surface material made of a nonwoven fabric or the like and a liquid-impermeable leak-proof material made of a polyethylene sheet or a polyethylene sheet laminated nonwoven fabric or the like are used. In addition, there has been known a hydrophilic absorbent paper that physically absorbs and holds blood and an absorbent body made of cotton-like pulp. Among these, regarding the material of the absorbent body, it has been proposed to improve the blood absorption capacity by using a water-absorbing resin instead of absorbent paper or pulp, and to prevent leakage due to retention of blood after absorption.
[0003]
As this type of water-absorbing resin, starch-acrylonitrile graft copolymer hydrolyzate, carboxymethylcellulose crosslinked product, polyacrylic acid (salt) crosslinked product, acrylic acid (salt) -vinyl alcohol copolymer, Polyethylene oxide crosslinked products and the like are known.
[0004]
However, in the case of sanitary napkins using these conventional water-absorbing materials, there is still a strong demand for leakage prevention, as is evident from the fact that the first complaint of consumers is leakage. The reality was that I was not satisfied. For these reasons, there has been a strong demand for the development of a water-absorbing material and blood-absorbing article in which the absorption characteristics are not significantly reduced by blood components.
[0005]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a water-absorbing material having improved blood absorption characteristics and a blood-absorbing article using the same.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have obtained a water absorbent resin containing a polyamino acid or a salt thereof, wherein the water absorbent resin particles are joined to each other. It has been found that the absorption characteristics of blood can be improved by using it, and the present invention has been completed.
[0007]
That is, the present invention provides a water-absorbent material comprising a polyamino acid or a salt thereof, wherein the water-absorbent resin particles are joined to each other,
[0008]
Moreover, this invention provides the article for blood absorption characterized by including this water absorbing material.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, specific matters necessary for carrying out the present invention will be described below.
[0010]
The water-absorbing material used in the present invention is a water-absorbing resin containing a polyamino acid or a salt thereof, and is characterized in that particles of the water-absorbing resin are joined together.
[0011]
Furthermore, the water-absorbing material used in the present invention has an average particle size in a bonded state of preferably 100 μm to 1000 μm, more preferably 150 μm to 500 μm in that the affinity for blood can be increased. It is a range.
[0012]
The water-absorbing resin containing a polyamino acid or a salt thereof in the present invention is not particularly limited as long as it is a water-absorbing resin containing a polyamino acid or a salt thereof. Specific examples include, for example, polyglutamic acid or a salt thereof, polylysine or a salt thereof, polyaspartic acid or a salt thereof, a glutamic acid copolymer or a salt thereof, an aspartic acid copolymer or a salt thereof obtained by crosslinking. Resin; obtained by reacting an anhydrous polyacidic amino acid having at least one ethylenically unsaturated bond in the molecule with a polysaccharide and hydrolyzing a part or all of a crosslinked product obtained by reacting a crosslinking agent. Water-absorbing resin obtained by reacting polyamino acid, polysaccharide and cross-linking agent; water-absorbing resin obtained by hydrolyzing the cross-linking reaction product of anhydrous polyamino acid and polysaccharide; polyamino acid and protein Water-absorbent resin obtained by reacting with water; Hydrolysis of the product of cross-linking reaction between anhydrous polyamino acid and protein At least one ethylenically anhydrous poly acidic amino acid having an unsaturated bond, the water-absorbent resin obtained by reacting an ethylenically unsaturated compound can be exemplified in the molecule; water absorbent resin obtained Te.
[0013]
The water-absorbing material used in the present invention preferably has a blood suction amount of 3 g / g or more in the blood suction amount measurement method defined in the examples described later, and has at least one ethylenic molecule in the molecule. A water-absorbing material containing a water-absorbing resin obtained by reacting an anhydrous polyacidic amino acid (A) having an unsaturated bond with an ethylenically unsaturated compound (B) is preferred.
[0014]
The water-absorbing resin obtained by reacting the anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule used in the present invention with the ethylenically unsaturated compound (B) A known radical polymerization of an anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond therein, an ethylenically unsaturated compound (B) and, if necessary, a polysaccharide in the presence of a crosslinking agent (C) It can be obtained by a polymerization method using an initiator.
[0015]
As the anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule used in the present invention, polysuccinimide having a maleimide terminal group as a terminal group can be used as it is. The polysuccinimide having a maleimide end group can be obtained by, for example, reacting maleic anhydride, fumaric acid, malic acid, etc. with ammonia and heating to maleimide or maleamic acid.
[0016]
Furthermore, the anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule includes an anhydrous polyacidic amino acid and a functional group having reactivity with the ethylenically unsaturated bond and the anhydrous polyacidic amino acid in the molecule. The compound obtained by making it react with the compound which has group may be sufficient.
[0017]
The anhydrous polyacidic amino acid may have a linear structure or a branched structure as long as it is an anhydride such as polyaspartic acid or polyglutamic acid. Further, it may partially contain an amide bond. Further, the basic skeleton may contain a bond with an amino acid derivative other than glutamic acid and aspartic acid (that is, it may be a copolymer). Examples of amino acid derivatives other than glutamic acid and aspartic acid include fats such as glycine, alanine, valine, leucine, isoleucine, serine, threonine, asparagine, glutamine, lysine, ornithine, cysteine, cystine, methionine, proline, hydroxyproline, and arginine. Aromatic α-amino acids, aromatic α-amino acids such as tyrosine, phenylalanine, tryptophan, histidine, those in which the side chain functional groups of these α-amino acids are substituted, aminocarboxylic acids such as β-alanine, γ-aminobutyric acid, glycyl -Dipeptides (dimers) such as glycine and aspartyl-phenylalanine, and tripeptides (trimers) such as glutathione. These amino acid derivatives may be optically active (L-form, D-form) or racemic. These bonds may be present randomly (random copolymer) or in blocks (block copolymer).
[0018]
The compound having a functional group having reactivity with an ethylenically unsaturated bond and an anhydrous polyacidic amino acid in the molecule is preferably a compound represented by the following general formula [1].
[0019]
[Chemical 1]

[0020]
(However, in general formula [1], R ₁ Is at least one group selected from the group consisting of amino group, epoxy group, carboxyl group, carbodiimide group, oxazoline group, imino group, and isocyanate group, -Q- is an alkylene group having 1 to 10 carbon atoms, R ₂ Is hydrogen or an alkyl group having 1 to 4 carbon atoms. )
[0021]
Examples of the compound represented by the general formula [1] include, but are not limited to, glycidyl acrylate, glycidyl methacrylate, acrylic acid, methacrylic acid, 2-methacryloyloxyethyl isocyanate, and 2-isocyanate methyl acrylate. Not.
[0022]
The ethylenically unsaturated compound (B) used in the present invention can be any water-soluble or water-miscible compound. For example, (meth) acrylic acid and / or an alkali metal salt thereof, Ionic monomers such as ammonium salts, 2- (meth) acrylamide-2-methylsulfonic acid and / or alkali metal salts thereof; (meth) acrylamide, N, N-dimethylacrylamide, 2-hydroxyethyl (meth) acrylate, N -Nonionic monomers such as methylol (meth) acrylamide; amino group-containing unsaturated monomers such as diethylaminoethyl (meth) acrylate and dimethylaminopropyl (meth) acrylate, and quaternized products thereof. One kind or two or more kinds selected from the group can be used. Here, the term “(meth) acryl” means both “acryl” and “methacryl”. Among these, (meth) acrylic acid and / or its alkali metal salt, alkaline earth metal salt, ammonium salt, and (meth) acrylamide are preferable, and the alkali metal salt includes sodium salt, potassium salt, lithium salt. , Rubidium salts, and alkaline earth metal salts include calcium salts, magnesium salts, and the like.
[0023]
The ethylenically unsaturated compound (B) used in the present invention is a polyfunctional ethylene having two or more ethylenically unsaturated groups as a crosslinking agent (C) in a water-soluble or water-miscible ethylenically unsaturated compound. It is more preferable to use a polymerizable unsaturated compound or a compound having two or more reactive groups in combination.
[0024]
As the polyfunctional ethylenically unsaturated compound, basically any compound can be used as long as it is an ethylenically unsaturated compound having two or more ethylenically unsaturated groups. For example, N, N′— Methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate, glycerin tri (meth) ) Acrylate, glycerin acrylate methacrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like.
[0025]
Examples of the compound having two or more reactive groups include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, 1,4-butanediol, and 1,5-pentane. Polyols such as diol, 1,6-hexanediol, neopentyl alcohol, diethanolamine, tridiethanolamine, polypropylene glycol, polyvinyl alcohol, pentaerythritol, sorbitol, sorbitan, glucose, mannitol, mannitan, sucrose, glucose; ethylene glycol Polyglycidyl ethers such as diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin triglycidyl ether; epichlorohydride Halo-epoxy compounds such as α-methylchlorohydrin; polyaldehydes such as glutaraldehyde and glyoxal; polyamines such as ethylenediamine; calcium hydroxide, calcium chloride, calcium carbonate, calcium oxide, magnesium borax chloride, magnesium oxide, aluminum chloride , Zinc chloride and nickel chloride, etc. Periodic Table 2A, 3B and 8 group metal hydroxides, halides, carbonates, oxides, borates such as borax, polyvalent metal compounds such as aluminum isopropylate Etc. These polyfunctional ethylenically unsaturated compounds having two or more ethylenically unsaturated groups or compounds having two or more reactive groups are used in consideration of reactivity. I can do it.
[0026]
Examples of the polysaccharide used in the present invention include starch, cellulose, and alginic acid. The starch includes all starches and starch-containing materials and their modified products, which are generally made of amylose and / or amylopentine, of natural or plant origin. Examples of the starch include potato starch, onion starch, wheat starch, tapioca starch, rice starch, sweet potato starch, sago starch, waxy cons, high amylose cons, wheat flour, rice flour and the like. As modified starch, starch is grafted with monomers such as acrylic ester, methacrylic ester, olefin, styrene, etc., reacted with fatty acid, etc., and these are dextrinized, oxidized, Acid-treated, alpha-treated, etherified, esterified or crosslinked can also be used. Moreover, the structure modified starch (EP0327505 A2) which heated the starch containing a water | moisture to the temperature higher than the glass transition temperature and melting temperature is included. Furthermore, polysaccharides such as guar gum, chitin, chitosan, cellulose, alginic acid and agar can also be used. Examples of cellulose include cellulose obtained from wood, leaves, stems, ginseng, seed hair, etc .; processing of alkyl etherified cellulose, organic acid esterified cellulose, carboxymethylated cellulose, oxidized cellulose, hydroxyalkyl etherified cellulose, etc. A cellulose is mentioned.
[0027]
A water-absorbent resin comprising a polyamino acid or a salt thereof according to the present invention, wherein the water-absorbent material is a state in which particles of the water-absorbent resin are joined to each other. The water-absorbent material has at least one ethylenically unsaturated bond in the molecule. In a container, a method of polymerizing a polyacidic amino acid (A), an ethylenically unsaturated compound (B) and, if necessary, a polysaccharide in the presence of a cross-linking agent (C), for example, in a double kneader while stirring. Surface crosslinking treatment of polymer particles obtained by polymerization methods using known radical polymerization initiators such as cast polymerization method, continuous stationary polymerization on a driving belt, reverse phase suspension polymerization method, etc. It can manufacture by performing. Among these methods, a water-in-oil type reverse-phase suspension polymerization method using a radical polymerization initiator in the presence of a surfactant (D) in an inert solvent in that polymer particles can be easily obtained. It is preferable to produce the polymer particles by subjecting them to surface cross-linking treatment.
[0028]
Examples of the radical polymerization initiator used in the present invention include inorganic peroxides (hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.), organic peroxides (benzoyl peroxide, di-t-butyl). Peroxide, cumene hydroxy peroxide, succinic acid peroxide, di (2-ethoxyethyl) peroxydicarbonate, etc.), azo compounds (azobisisobutylnitrile, azobiscyanovaleric acid, 2,2′-azobis (2-aminopropane) ) Hydrochloride, etc.) and redox catalyst (alkali metal sulfite or bisulfite, ammonium sulfite, ammonium bisulfite, ascorbic acid etc. reducing agent and alkali metal persulfate, ammonium persulfate, peroxide etc. oxidizing agents A combination of these).
[0029]
By the reverse phase suspension polymerization method, a slurry-like mixture composed of the hydrogel, excess surfactant and inert solvent is obtained. The slurry after the polymerization can be obtained by a known method, for example, by direct dehydration or azeotropic dehydration with an inert solvent, followed by drying, sieving, etc.
[0030]
In this case, as the surfactant (D) used, any surfactant can be used as long as it is soluble or compatible with a hydrophobic solvent and basically forms a water-in-oil emulsion system. As such a surfactant, generally, HLB (Hydrophile-Lipophile-Balance) is preferably in the range of 1 to 9, more preferably in the range of 2 to 7 in nonionic and / or anionic systems. is there.
[0031]
Specific examples of the surfactant (D) used in the present invention include, for example, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, sucrose fatty acid ester, polyglycerin fatty acid ester, polyoxyethylene alkylphenyl ether, ethyl cellulose, ethyl hydroxy Examples include ethyl cellulose, polyethylene oxide, maleic anhydride polyethylene, maleic anhydride polybutadiene, maleic anhydride ethylene / propylene / diene / terpolymer, α-olefin / maleic anhydride copolymer or its derivative polyoxyethylene alkyl ether phosphoric acid, etc. It is done. Two or more of these surfactants can be used in combination as appropriate.
[0032]
The usage-amount of surfactant (D) used by this invention becomes like this. Preferably it is 0.05-10 weight% with respect to an inert solvent, More preferably, it is the range of 0.1-1 weight%. As long as the amount of the surfactant (D) used is within such a range, a stable reversed-phase suspension can be maintained, and in the finally obtained water-absorbent resin, the blood absorption characteristics of the present invention are intended. Can bring
[0033]
The inert solvent used in the present invention is a hydrophobic solvent that is hardly soluble in water, and any solvent can be used as long as it is inert to the polymerization reaction, and there is no particular limitation. Examples of the inert solvent include aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatics such as benzene, toluene, and xylene. Group hydrocarbons and the like. In these, n-hexane, n-heptane, and cyclohexane are preferable.
[0034]
The amount of the inert solvent used is preferably in the range of 0.5 to 10 times by weight with respect to the aqueous solution of the ethylenically unsaturated compound (B) used in the first stage reaction.
[0035]
As a more specific implementation method of the reverse phase suspension polymerization method used in the present invention, for example, ethylene that has been neutralized with one or more of the ethylenically unsaturated compounds (B) used in advance as required A water-soluble chain transfer agent such as a crosslinking agent (C), a radical polymerization initiator, and, if necessary, thiols, thiolic acids, secondary alcohols, amines, hypophosphites, etc. An aqueous solution of the ethylenically unsaturated compound (B) dissolved by addition is prepared, and degassing is performed by introducing an inert gas such as nitrogen. On the other hand, the surfactant (D) is placed in an inert solvent in the polymerization apparatus, and if necessary, heated and dissolved slightly, and an inert gas such as nitrogen is introduced to perform deaeration. The aqueous solution of the ethylenically unsaturated compound (B) is poured into this, and the temperature rise is started with stirring. During this time, the aqueous solution of the reaction system becomes fine droplets and is suspended while being dispersed in an inert solvent. Over time, heat generation occurs and the polymerization starts.
[0036]
In the present invention, the method for adding the anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule is not particularly limited. (1) At least one ethylene in the molecule hydrolyzed in advance. A method in which an aqueous solution of an anhydrous polyacidic amino acid (A) having an ionic unsaturated bond is previously mixed with an aqueous solution of an ethylenically unsaturated compound (B); (2) simultaneously with an aqueous solution of an ethylenically unsaturated compound (B) Injecting method; (3) Method of injecting at elevated temperature; (4) Method of injecting after heat generation occurs and polymerization is started, any of them may be used, but in this, the stability of the system can be further maintained. (4) A method of injecting after the occurrence of exotherm and initiation of polymerization is preferred. When an aqueous solution of the anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule is added after the exotherm occurs and the polymerization starts, the aqueous solution may be added as it is.
[0037]
In addition, it is better to add an inert solvent in which a surfactant is dissolved to an aqueous solution of an anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule, and after stirring and dispersing, More preferable is that the particles do not aggregate and the polymerization stability is improved. The surfactant used at this time may be any one of the surfactants (D) used in the above-mentioned reversed-phase suspension polymerization method, and may be used alone or in combination of two or more. It is more preferable to use a surfactant having a higher HLB value than the surfactant used for monomer polymerization. Specifically, such surfactants are generally preferably nonionic and / or anionic surfactants having an HLB value of 4 to 18.
[0038]
The timing of injection after the exotherm is not particularly limited, but is preferably between immediately after the exotherm and after 3 hours, more preferably between immediately after the exotherm and after 2 hours. By injecting at this time, water-absorbent resin particles that are being formed in the reaction system without separation of an aqueous solution of an anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule Since it can be taken in, it is preferable.
[0039]
Moreover, in the ethylenically unsaturated compound (B) to be used in advance, an ethylenically unsaturated compound aqueous solution obtained by neutralizing one or more kinds as necessary, a crosslinking agent, a radical polymerization initiator, and, if necessary, An aqueous solution of an ethylenically unsaturated compound in which a water-soluble chain transfer agent such as thiols, thiolic acids, secondary alcohols, amines, hypophosphites and the like is added and dissolved can be sequentially supplied. Thus, it is possible to easily obtain a water absorbent resin in a joined state. The method of sequential supply is not particularly limited. For example, (1) a method of sequentially polymerizing an aqueous solution of the ethylenically unsaturated compound (B) dropwise into an inert solvent; (2) ethylenic A method in which an aqueous solution of an unsaturated compound (B) is successively polymerized while being dropped dropwise into an inert solvent; (3) An aqueous solution of the ethylenically unsaturated compound (B) is mixed with a part of the inert solvent in advance. Alternatively, there is a method in which a mixed / dispersed solution obtained by dispersion is polymerized while being dropped into an inert solvent.
[0040]
At this time, the method for adding the anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule is not particularly limited, but at least one ethylenically unsaturated bond in the previously hydrolyzed molecule. (1) A method in which an aqueous solution of an anhydrous polyacidic amino acid (A) having a mixture of (1) an aqueous solution of an ethylenically unsaturated compound (B) is previously mixed and added dropwise; (2) An aqueous solution of the ethylenically unsaturated compound (B) is added simultaneously. (3) A method of batch injection or subsequent dropping after completion of dropping of the aqueous solution of the ethylenically unsaturated compound (B). At this time, as described above for stable polymerization, an inert solvent in which a surfactant is dissolved is added to an aqueous solution of an anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule. In addition, after stirring and dispersing, it may be added to the polymerization solution.
[0041]
The mixing ratio of the inert solvent and the entire aqueous solution in the present invention is usually preferably in the range of 10/1 to 0.5 / 1 weight ratio, more preferably 5/1 to 0.8 / 1 weight ratio. If the ratio of the aqueous solution of the inert solvent and the ethylenically unsaturated compound (B) is within the range of the above weight ratio, the polymerization stability is good, the heating of polymerization heat is facilitated, and the productivity is increased, which is preferable. .
[0042]
After the polymerization is started, cooling or heating is appropriately performed depending on the state of heat generation. The polymerization reaction temperature is not particularly limited, but is usually preferably in the range of 60 to 100 ° C, more preferably 60 to 80 ° C.
[0043]
In addition, the stirring condition cannot be uniquely shown because the absolute value varies depending on the type of stirring blade used and the scale of the polymerization reaction tank, and the stirring speed is determined by the polymer particles. It is preferable to control the stirring power according to the type of the stirring blade, since the average particle size after bonding is preferably controlled in the range of 100 μm to 1000 μm. Although it can select suitably, it is preferable that it is the range of 50-1000 rpm normally. By appropriately selecting the type of stirring blade and the stirring power within the range of the stirring rotation speed within this range, the polymer particles of the water-absorbing resin having both the affinity for blood and the absorption characteristics that are the object of the present invention are obtained. I can do it.
[0044]
The water absorbent resin according to the present invention is a water absorbent resin obtained by reacting an anhydrous polyacidic amino acid (A) having at least one ethylenically unsaturated bond in the molecule with an ethylenically unsaturated compound (B). By performing a cross-linking reaction in the vicinity of the surface using the surface cross-linking agent (E), it is possible to make the bonding between the polymer particles even closer, and as a result, it is possible to further improve the absorption characteristics for blood. Furthermore, since the bonding state between the polymer particles obtained by reverse phase suspension polymerization can be further enhanced by surface crosslinking, the average particle size can be controlled in the range of 100 μm to 1000 μm.
[0045]
The surface cross-linking agent (E) used in the present invention has two or more functional groups capable of reacting with a functional group near the surface of the water-absorbent resin, and is used for blood-absorbing articles. A thing with high safety | security with respect to a human body is preferable. Examples of such compounds include compounds having a reactive group capable of reacting with two or more carboxyl groups (carboxylate groups) such as polyamine and polyglycidyl ether, and γ-glycidoxypropyltrimethoxysilane, γ Silane coupling agents such as glycidoxypropylmethyldiethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane are known as silanol condensation catalysts as necessary. In addition to dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, etc., it is also possible to use an ethylenically unsaturated compound having a reactive group such as glycidyl methacrylate with a radical polymerization initiator if necessary. is there.
[0046]
In the present invention, the surface cross-linking treatment is carried out by directly dehydrating the beads-like particles swollen after the reversed-phase suspension polymerization by an appropriate method such as azeotropic dehydration or heating, thereby drying to a predetermined moisture content. It can be performed by mixing the polymer and the surface cross-linking agent (E). At this time, in order to uniformly mix the surface cross-linking agent (E), it is preferable to use both water and a hydrophilic solvent, and water and the hydrophilic solvent are added to the surface cross-linking agent (E) with respect to 100 parts by weight of the polymer. Further, 50 parts by weight or less of water and 60 parts by weight or less of a hydrophilic solvent may be mixed and used.
[0047]
Examples of the hydrophilic solvent used in the present invention include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol, ketones such as acetone and methyl ethyl ketone, dioxane, and tetrahydrofuran. , And ethers such as diethyl ether, amides such as N, N-dimethylformamide and N, N-diethylformamide, and sulfoxides such as dimethyl sulfoxide.
[0048]
The mixing method in particular of a polymer and a surface crosslinking agent (E) is not restrict | limited, A normal mixer can be used. Examples of the mixing apparatus include a cylindrical mixer, a double wall conical mixer, a high-speed stirring mixer, a V-shaped mixer, a ribbon mixer, a screw mixer, and a fluid-type furnace rotary desk mixer. It is preferable to add a surface cross-linking agent while stirring the polymer in a mixing device such as an air-flow type mixer, a double arm type kneader, an internal mixer, a pulverizing type kneader, a rotary mixer, a screw type extruder, etc. It is more preferable that the agent is sprayed so that the agent is uniformly mixed.
[0049]
The heat treatment time for surface cross-linking is appropriately selected depending on the heating temperature, but since a water-absorbing resin having high water-absorbing performance is obtained without causing thermal degradation, usually, preferably at a temperature of 60 ° C. to 300 ° C., It is preferably 5 minutes to 100 hours or less.
[0050]
Although it does not specifically limit as a heat processing apparatus, Usually, a dryer or a heating furnace is used, for example, a groove type mixing dryer, a rotary dryer, a disk dryer, a fluidized bed dryer, an airflow type dryer, infrared rays Examples include a dryer and a vacuum dryer.
[0051]
Since the water-absorbing material according to the present invention exhibits particularly excellent absorption characteristics for blood, examples of blood-absorbing articles containing the water-absorbing material include sanitary napkins and tampons. Articles requiring blood absorption characteristics such as medical blood absorption sheets, drip absorbents, wound protection materials, wound healing materials, surgical waste liquid treatment agents and the like can be listed. In addition to the water-containing protein as well as blood, such as milk, breast milk, and urine, it has excellent absorption characteristics, as well as urine, seawater, cement water, soil water, Since it has excellent absorption characteristics for fertilizer-containing water, rainwater, drainage, etc., its application field is wide.
[0052]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the following, all percentages are based on weight unless otherwise specified. The various properties of the materials were measured by the methods outlined below. In addition, Table 1 summarizes the charged compositions of Examples 1 to 3 and Comparative Examples 1 and 2.
[0053]
[Measurement method of blood suction volume]
Horse defibrinated blood in a petri dish with an inner diameter of 95 mm (obtained from Japan Biomaterials Center Co., Ltd.) on 15-layer toilet paper (Silver Swan, manufactured by Kawamura Paper Co., Ltd.) immersed in 20 ml on a 55 mm x 75 mm area. Then, 1 g of a resin sample was added and allowed to absorb liquid for 10 minutes, and then a swelling gel of the sample was collected and its weight was measured. The blood suction amount b / a was calculated by dividing the weight b (g) of the swollen gel after liquid absorption by the weight a (g) of the resin sample before liquid absorption.
[0054]
[Method of measuring blood absorption rate and affinity for blood]
When 0.5 g of a resin sample was uniformly dispersed in a petri dish having an inner diameter of 70 mm and then 2.5 ml of equine defibrinated blood was added, the time taken for blood to be absorbed into the resin was taken as the blood absorption rate. Also, visually observe the affinity between the resin sample and the blood at this time, and if the blood penetrates almost the entire resin, it is “Affinity”. The case where it did not penetrate almost while riding was judged as “no affinity”.
[0055]
<< Reference Example >> Production Example of Polysuccinimide
96 g of maleic anhydride and 50 g of ion-exchanged water were added to a 1 L four-necked flask equipped with a stirrer, a thermometer, a reflux device, and a nitrogen gas blowing device. The mixture was heated to 55 ° C. to dissolve maleic anhydride, and then cooled once to obtain a maleic anhydride slurry. The system was heated again and when the temperature reached 55 ° C., 60.8 g of 28% aqueous ammonia was added. Thereafter, the temperature inside the system was heated to 80 ° C. After reacting for 3 hours, the obtained aqueous solution was dried to obtain a reaction intermediate. A 2 L eggplant flask was charged with 100 g of a reaction intermediate and 10 g of 85% phosphoric acid, and reacted for 4 hours using an evaporator at an oil bath temperature of 200 ° C. under reduced pressure. The resulting product was washed several times with water and methanol. As a result of measuring the obtained polysuccinimide by GPC, the weight average molecular weight was 3000.
[0056]
Example 1
After adding 75 g of an aqueous solution in which 20.6 g of sodium hydroxide was dissolved to a 500 ml four-necked flask equipped with a stirrer, a thermometer, a reflux apparatus, and a nitrogen gas blowing apparatus, the polysuccinic acid obtained in Reference Example 1 was added. An aqueous solution of polysuccinimide was obtained by adding 50 g of imide powder. Subsequently, after raising the temperature to 90 ° C., 5.0 g of glycidyl methacrylate was added and the reaction was carried out for 1 hour to obtain an aqueous solution containing a hydrolyzate of polysuccinimide into which a methacryl group was introduced. In a 100 ml Erlenmeyer flask, 0.75 g of HLB = 16 sucrose ester (DK ester F-160, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was weighed, 20 g of cyclohexane was added, and the mixture was heated to 50 ° C. and dissolved. To this, 7.8 g of the aqueous solution obtained by the above-mentioned operation was added and stirred to obtain a dispersion of an aqueous solution of polysuccinimide hydrolyzate into which a methacryl group was introduced.
[0057]
Separately, 164 g of cyclohexane was added to a 500 ml four-necked flask equipped with a stirrer, a thermometer, a reflux device, and a nitrogen gas blowing device, and HLB = 9 sucrose ester (Daiichi Kogyo Seiyaku Co., Ltd.) DK Ester F-90) 0.75 g was added and dissolved by heating to 50 ° C. with stirring. Thereafter, the contents of the flask were cooled to 30 ° C. On the other hand, 30 g of acrylic acid was added to a 500 ml Erlenmeyer flask, and 86.5 g of an aqueous sodium hydroxide solution in which 8.3 g of sodium hydroxide was dissolved was dropped while cooling from the outside to neutralize 50 mol% of acrylic acid. To this solution, 23.4 mg of N, N′-methylenebisacrylamide was added, and 0.05 g of ammonium persulfate was further added and dissolved. Next, the acrylate aqueous solution containing the polymerization initiator and the crosslinking agent obtained as described above is added to the contents of the cylindrical round bottom flask and dispersed in the cyclohexane solution containing the surfactant. At the same time, the inside of the system was sufficiently replaced with nitrogen. Thereafter, the temperature was raised by heating to initiate the polymerization reaction. After a while, heat generation was started, and 5 minutes after the peak of heat generation, the dispersion solution of the hydrolyzate solution of polysuccinimide into which the methacryl group had been introduced previously was added. Thereafter, the temperature was maintained at 60 to 65 ° C. for 3 hours. Stirring was performed at 300 rpm. After completion of the reaction, the cyclohexane phase was separated by decantation, and then water was removed from the wet polymer by drying under reduced pressure to obtain a polymer powder.
[0058]
30 g of polymer particles obtained in a 500 ml flask were weighed and mixed therewith 1.2 g of acetone, 2.1 g of ion-exchanged water, 0.09 g of glycidyl methacrylate, 0.09 g of ammonium persulfate, and hydrophilic silica (Japan Aerosil Co., Ltd. (200CF) 0.3 g was uniformly sprayed. The wet polymer was dried under reduced pressure at 108 ° C. for 1 hour to perform surface crosslinking treatment of the water absorbent resin. When the obtained water-absorbent resin was observed with a microscope, it was found that spherical resin particles were joined as shown in FIG. Table 2 shows the evaluation results of the characteristics of the water-absorbing material of the present invention. As shown in Table 2, the water-absorbing material obtained in Example 1 is excellent in blood suction ability (aspiration amount, absorption speed) and has an affinity for blood.
[0059]
Example 2
30 g of polymer particles obtained by the same operation as in Example 1 were weighed into a 500 ml flask, and mixed therewith 1.2 g of acetone, 2.1 g of ion-exchanged water, 0.09 g of glycidyl methacrylate, and 0.09 g of ammonium persulfate. The solution and 0.3 g of hydrophilic silica (Nippon Aerosil Co., Ltd., 200CF) were uniformly sprayed. The wet polymer was dried under reduced pressure at 180 ° C. for 1 hour to perform surface crosslinking treatment of the water absorbent resin. When the obtained water-absorbent resin was observed with a microscope, it was found that spherical resin particles were joined. Table 2 shows the evaluation results of the characteristics of the water-absorbing material of the present invention. As shown in Table 2, the water-absorbing material obtained in Example 2 is excellent in blood suction ability (aspiration amount, absorption speed) and has an affinity for blood.
[0060]
Example 3
Example, except that 30 g of acrylic acid was added and 81.5 g of a lithium hydroxide solution in which 8.7 g of lithium hydroxide monohydrate was dissolved was added dropwise while cooling from the outside to neutralize 50 mol% of acrylic acid. In the same manner as in No. 1, polymer powder was obtained. 30 g of polymer particles obtained in a 500 ml flask were weighed and subjected to surface cross-linking treatment of the water-absorbent resin in the same manner as in Example 2. When the obtained water-absorbent resin was observed with a microscope, it was found that spherical resin particles were joined. Table 2 shows the evaluation results of the characteristics of the water-absorbing material of the present invention. As shown in Table 2, the water-absorbing material obtained in Example 3 is excellent in blood suction ability (aspiration amount, absorption speed) and has an affinity for blood.
[0061]
<< Comparative Example 1 >>
30 g of acrylic acid was added, and 84.7 g of an aqueous sodium hydroxide solution in which 8.3 g of sodium hydroxide was dissolved was added dropwise while cooling from the outside to neutralize 50 mol% of acrylic acid, and N, N′- 23.4 mg of methylenebisacrylamide was added, and 0.05 g of ammonium persulfate was further added and dissolved. Next, the acrylate aqueous solution containing the polymerization initiator and the crosslinking agent obtained as described above is added to the contents of the cylindrical round bottom flask and dispersed in the cyclohexane solution containing the surfactant. At the same time, the inside of the system was sufficiently replaced with nitrogen. Thereafter, the temperature was raised by heating, and the polymerization reaction was started, and thereafter kept at 60 to 65 ° C. for 3 hours. Stirring was performed at 300 rpm. After completion of the reaction, the cyclohexane phase was separated by decantation, and then water was removed from the wet polymer by drying under reduced pressure to obtain a polymer powder.
[0062]
30 g of polymer particles obtained in a 500 ml flask were weighed and subjected to surface cross-linking treatment by the same operation as in Example 1. When the obtained water-absorbent resin was observed with a microscope, the spherical resin particles were hardly joined as shown in FIG. Table 2 shows the property evaluation results of the water-absorbing material obtained here.
[0063]
<< Comparative Example 2 >>
The same operation as Comparative Example 1 except that 30 g of acrylic acid was added and 90.3 g of an aqueous sodium hydroxide solution in which 13.8 g of potassium hydroxide was dissolved was added dropwise while cooling from the outside to neutralize 50 mol% of acrylic acid. Thus, a water-absorbent resin powder was obtained. Table 2 shows the property evaluation results of the water-absorbing material obtained.
[0064]
[Table 1]

[0065]
Abbreviated substance names in Table 1 are as follows.
GMA: Glycidyl methacrylate
MBAA: N, N-methylenebisacrylamide
APS: ammonium persulfate
[0066]
[Table 2]

[0067]
【Effect of the invention】
According to the present invention, a water-absorbing resin comprising a polyamino acid or a salt thereof, wherein the water-absorbing material is in a state in which particles of the water-absorbing resin are joined to each other. , Absorption rate, affinity, etc.), and a water-absorbing material and blood-absorbing article in which the absorption characteristics are not significantly reduced by blood components can be provided.
[Brief description of the drawings]
FIG. 1 is a photomicrograph of the water-absorbing material of the present invention obtained in Example 1. FIG. It can be seen that spherical resin particles are joined as shown in FIG.
FIG. 2 is a photomicrograph of the water-absorbing material obtained in Comparative Example 1. As shown in FIG. 2, it can be seen that the spherical resin particles are hardly joined.

Claims (3)

A water-absorbent resin containing a polyamino acid or a salt thereof, wherein the water-absorbent resin has at least one ethylenically unsaturated bond in the molecule, an anhydrous polyacidic amino acid (A), (meth) acrylic acid, and an alkali metal salt thereof (B) obtained by reverse phase suspension polymerization of water-in-oil type in an inert solvent in the presence of N, N′-methylenebis (meth) acrylamide (C) and surfactant (D). A water-absorbing material obtained by subjecting coalesced particles to a surface cross-linking treatment with glycidyl methacrylate (E) , wherein the particles of the water-absorbing resin are joined to each other. The water-absorbing material according to claim 1 , wherein the blood suction amount is 3 g / g or more in blood suction amount measurement. A blood-absorbing article comprising the water-absorbing material according to claim 1 .

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