JP3644738B2 - Absorbent sheet, manufacturing method thereof, and absorbent article - Google Patents

Description

【０１２３】
〔製造例７〕
親水性の微細繊維の製造
精選パルプを酸加水分解し、水洗乾燥後、機械的な粉砕により微細繊維化した、平均繊維長０．１２ｍｍ、繊維粗度０．０９ｍｇ／ｍ、繊維断面の真円度０．３１のセルロース繊維〔山陽国策パルプ（株）製の「KCフロック W-100 」（商品名）〕を用いた以外は、製造例１と同様の方法にて架橋処理した親水性の微細繊維を得た。これを親水性微細繊維（Ｇ）とする。
【０１２４】
〔製造例８〕
親水性の微細繊維の製造
精選パルプを酸加水分解し、水洗乾燥後、機械的な粉砕により微細繊維化した、平均繊維長０．１２ｍｍ、繊維粗度０．０９ｍｇ／ｍ、繊維断面の真円度０．３２のセルロース繊維〔山陽国策パルプ（株）製の「KCフロック W-100 」（商品名）〕を用意した。これを親水性微細繊維（Ｈ）とする。なお、親水性微細繊維（Ｈ）は架橋されていない。
【０１２５】
〔実施例１〕
吸収性シートの製造
セルロース繊維（Ａ）９５部、及び太さ１デニール、長さ３ｍｍのポリビニルアルコール繊維〔三昌（株）製のフィブリボンド（商品名）、以下ＰＶＡ繊維と称す〕５部を水中に分散混合し、所定の濃度とした後、この分散混合液を湿式抄紙機のフォーミングパートで乾燥坪量が７０ｇ／ｍ² になるように繊維ウェブを形成した。次いで、該繊維ウェブをサクションボックスにより、乾燥繊維ウェブ１００部に基づき水分率１５０部になるまで、繊維ウェブを脱水した。次いで、プレスパート直前で、脱水後の湿潤した繊維ウェブ上に、親水性微細繊維（Ｇ）を散布坪量２０ｇ／ｍ² でほぼ均一に散布し、更に高吸収性ポリマー〔日本触媒（株）製、アクアリックCAW-4 （商品名）〕を散布坪量５０ｇ／ｍ² でほぼ均一に散布した。
上記繊維ウェブのうち、上記親水性微細繊維（Ｇ）と高吸収性ポリマーとをそれぞれ散布した面に、繊維集合体として、上記繊維ウェブと同様の配合組成を有する、予め抄紙しておいた吸収紙（３０ｇ／ｍ² ）を重ね合わせ、かかる繊維ウェブと吸収紙との重ね合わせ体をドライヤーに導入し、１３０℃にて乾燥、一体化することにより、内部に親水性微細繊維（Ｇ）と高吸収性ポリマーとが固定されている、一枚の吸収性シートを得た。この吸収性シートを吸収性シート（Ａ）とする。
【０１２６】
〔実施例２〕
吸収性シートの製造
セルロース繊維（Ｂ）９５部、及び太さ１．１デニール、長さ５ｍｍの低融点ポリエステル繊維〔帝人（株）製のTM-07N（商品名）、以下ＰＥＴ繊維と称す〕５部を水中に分散混合し、所定の濃度とした後、この分散混合液を湿式抄紙機のフォーミングパートで乾燥坪量が７０ｇ／ｍ² になるように繊維ウェブを形成した。次いで、該繊維ウェブをサクションボックスにより、乾燥繊維ウェブ１００部に基づき水分率１００部になるまで、繊維ウェブを脱水し、プレスパートを通した後の湿潤した繊維ウェブ上に、親水性微細繊維（Ｇ）を散布坪量２０ｇ／ｍ² でほぼ均一に散布し、更に高吸収性ポリマー〔日本触媒（株）製、アクアリックCAW-4 （商品名）〕を散布坪量５０ｇ／ｍ² でほぼ均一に散布した。
上記繊維ウェブのうち、上記親水性微細繊維（Ｇ）と高吸収性ポリマーとをそれぞれ散布した面に、繊維集合体として、上記繊維ウェブと同様の配合組成を有する、予め抄紙しておいた吸収紙（３０ｇ／ｍ² ）を重ね合わせ、かかる繊維ウェブと吸収紙との重ね合わせ体をドライヤーに導入し、１３０℃にて乾燥、一体化することにより、内部に親水性の微細繊維と高吸収性ポリマーとが固定されている、一枚の吸収性シートを得た。この吸収性シートを吸収性シート（Ｂ）とする。
【０１２７】
〔実施例３〕
吸収性シートの製造
表１に示す配合を用い、親水性微細繊維と高吸収性ポリマーとを均一混合したものをほぼ均一にそれぞれが散布坪量５０ｇ／ｍ² となるように散布する以外は実施例２と同様の操作により吸収性シートを得た。この吸収性シートを吸収性シート（Ｃ）とする。
【０１２８】
〔実施例４〕
吸収性シートの製造
表１に示す配合を用い、親水性微細繊維と高吸収性ポリマーとを均一混合したものをほぼ均一にそれぞれが散布坪量５０ｇ／ｍ² となるように散布する以外は実施例１と同様の操作により吸収性シートを得た。この吸収性シートを吸収性シート（Ｄ）とする。
【０１２９】
〔実施例５及び６〕
吸収性シートの製造
表１に示す配合を用い、親水性微細繊維と高吸収性ポリマーとを均一混合したものをほぼ均一にそれぞれが散布坪量５０ｇ／ｍ² となるように散布する以外は実施例１と同様の操作により吸収性シートを得た。この吸収性シートをそれぞれ吸収性シート（Ｅ）及び（Ｆ）とする。
【０１３０】
〔比較例１〕
吸収性シートの製造
セルロース繊維（Ｄ）９５部、及び太さ１デニール、長さ３ｍｍのＰＶＡ繊維５部を水中に分散混合し、抄紙機を用いて抄紙した後、乾燥して、坪量７０ｇ／ｍ² の吸収紙を予め製造した。該吸収紙を用いて吸収性シートを下記の方法により製造した。
即ち、上記吸収紙の上に該吸収紙（乾燥）１００部に基づき２００部になるまで水を散布する。次いで、湿潤した上記吸収紙の上に高吸収性ポリマー〔日本触媒（株）製、アクアリックCAW-4 （商品名）〕を散布坪用５０ｇ／ｍ² でほぼ均一に散布した。
上記吸収紙のうち、上記高吸収性ポリマーを散布した面に、上記吸収紙と同様の配合組成を有する坪量３０ｇ／ｍ² の吸収紙を重ね合わせ、かかる２枚の吸収紙の重ね合わせ体を圧着一体化した後、ドライヤーで乾燥し、トータル坪量１５０ｇ／ｍ² の吸収性シートを得た。この吸収性シートにおける、高吸収性ポリマーを散布した吸収紙は、水を散布した後においても、その構成繊維は互いに強く拘束された状態にあり、本発明にいう繊維ウェブの状態ではない。また、上記吸収性シートは、かかる吸収紙の間に高吸収性ポリマーが層状にサンドイッチされたものである。この吸収性シートを吸収性シート（Ｇ）とする。
【０１３１】
〔比較例２〕
吸収性シートの製造
セルロース繊維（Ｅ）９５部、及び太さ１．１デニール、長さ５ｍｍの低融点ＰＥＴ繊維５部を水中に分散混合し、抄紙機を用いて抄紙した後、乾燥して、坪量７０ｇ／ｍ² の吸収紙を予め製造した。該吸収紙を用いて吸収性シートを下記の方法により製造した。
即ち、上記吸収紙の上に、接着剤〔ヘキスト合成（株）のモビニール710 （商品名）〕を坪量２０ｇ／ｍ² で塗布し、次いで、上記吸収紙の上に高吸収性ポリマー〔日本触媒（株）製、アクアリックCAW-4 （商品名）〕を散布坪量５０ｇ／ｍ² でほぼ均一に散布した。
上記吸収紙のうち、上記高吸収性ポリマーを散布した面に、上記吸収紙と同様の配合組成を有する坪量３０ｇ／ｍ² の吸収紙を重ね合わせ、かかる２枚の吸収紙の重ね合わせ体を圧着一体化した後、ドライヤーで乾燥し、トータル坪量１５０ｇ／ｍ² の吸収性シートを得た。この吸収性シートにおける、高吸収性ポリマーを散布した吸収紙は、湿潤した繊維ウェブの状態ではなく、パルプ繊維が互いに強く拘束されたものであり、しかも、２枚の吸収紙の間に高吸収性ポリマーが層状にサンドイッチされたものである。この吸収性シートを吸収性シート（Ｈ）とする。
【０１３２】
〔比較例３〕
吸収性シートの製造
セルロース繊維（Ｆ）９５部、及び太さ１デニール、長さ３ｍｍのＰＶＡ繊維５部を水中に分散混合し、抄紙機を用いて抄紙した後、乾燥して、坪量７０ｇ／ｍ² の吸収紙を予め製造した。該吸収紙を用いて吸収性シートを下記の方法により製造した。
即ち、上記吸収紙の上に該吸収紙（乾燥）１００部に基づき１０部になるまで水を散布する。次いで、湿潤した吸収紙の上に高吸収性ポリマー〔日本触媒（株）製、アクアリックCAW-4 （商品名）〕を散布坪量５０ｇ／ｍ² でほぼ均一に散布した。
上記吸収紙のうち、上記高吸収性ポリマーを散布した面に、上記吸収紙と同様の配合組成を有する坪量３０ｇ／ｍ² の吸収紙を重ね合わせ、かかる２枚の吸収紙の重ね合わせ体を縦及び横方向で５ｍｍの区間で仕切られた格子エンボスロールを通してエンボス圧着一体化した後、ドライヤーで乾燥し、トータル坪量１５０ｇ／ｍ² の吸収性シートを得た。この吸収性シートにおける、高吸収性ポリマーを散布した吸収紙は、水を散布した後においても、その構成繊維は互いに強く拘束された状態にあり、本発明にいう繊維ウェブの状態ではない。また、上記吸収性シートは、かかる吸収紙の間に高吸収性ポリマーが層状にサンドイッチされたものである。この吸収性シートを吸収性シート（Ｉ）とする。
【０１３３】
〔比較例４〕
吸収性シートの製造
エアーレイド法により形成した坪量４５ｇ／ｍ² のパルプシート間に、高吸収性ポリマーを４５ｇ／ｍ² になるように散布し、次いで、ケミカルバインダーでパルプを固定させた吸収性シートを製造した。
この吸収性シートを吸収性シート（Ｊ）とする。
【０１３４】
〔比較例５〕
吸収性シートの製造
合成パルプ及び高吸収性ポリマーを含む乾式吸収性シートを製造した。
即ち、ポリエチレンの合成パルプ２５部、及び化学パルプ７５部からなるパルプシートをハンマーミルで解繊し、坪量１００ｇ／ｍ² の乾式吸収性シートを形成する際に、高吸収性ポリマー〔日本触媒（株）製、アクアリックCAW-4 （商品名）〕を５０ｇ／ｍ² になるように原料中に混合し、その後熱風処理により、ポリエチレン合成パルプを融着させ、一体化させた。この乾式吸収性シートは、その表面にも高吸収性ポリマーが存在するものである。この吸収性シートを吸収性シート（Ｋ）とする。
【０１３５】
実施例１〜４における吸収性シート（Ａ）〜（Ｆ）及び比較例１〜５における吸収性シート（Ｇ）〜（Ｋ）の配合組成及び製造方法をそれぞれ表１及び表２に示す。
【０１３６】
【表１】

【０１３７】
【表２】

【０１３８】
実施例１〜６における吸収性シート（Ａ）〜（Ｆ）及び比較例１〜５における吸収性シート（Ｇ）〜（Ｋ）について、高吸収性ポリマー固定化能及び吸収性能を評価するために、下記に示す方法によって厚み、高吸収性ポリマーの脱落試験、飽和吸収量、吸収速度、及び液戻り量を測定した。それぞれの結果を表３に示す。
【０１３９】
＜厚み＞
適当な大きさに切断した吸収性シートの上面に２．５ｇ／cm² の荷重をかけ、その厚みを測定した。計１０点の平均値をとって、その厚みとした。
【０１４０】
＜高吸収性ポリマーの脱落試験＞
７０×２００mmに切り出した吸収性シートの重量を測定した後、これを長さ２８０mm×幅２００mmのチャック付きのポリ袋に入れ、この状態で５０回手で振りながら振動を与える。試験終了後、吸収性シートの重量変化を測定するとともに、ポリ袋中に脱落した高吸収性ポリマーが肉眼でよく観察できるよう、青色一号で染色した色水（０．３ｇ／水１００ml）をポリ袋中に加え、高吸収性ポリマーを膨潤させ、目視で脱落の程度を判定する。
○・・・高吸収性ポリマーの脱落が殆ど認められない。
△・・・高吸収性ポリマーの脱落が多少認められる。
×・・・高吸収性ポリマーの脱落がかなり認められる。
測定は１０回の試験を行い、その平均値をもって脱落量とした。
【０１４１】
＜飽和吸収量＞
５cm角の吸収性シートを不織布で作製した袋に入れ、袋ごとイオン交換水に１０分間浸漬した。袋をイオン交換水から取り出した後、空気中に１時間吊るし、付着している水を落とした後、重量を測定し、吸収性シート１ｇ当たりの重量の増加分を飽和吸収量（ｇ／ｇ）とした。
【０１４２】
＜吸収速度＞
図１２に示すように、１５cm角の吸収性シート１００の中央に、直径１cmの孔をあけた１０cm角の透明なアクリル板２０及び重り２２を乗せ、吸収性シート１００に５ｇ／cm² の荷重をかけた状態で、上記孔を通して生理食塩水２０mlを注入し、生理食塩水の吸収に要する時間を吸収速度とした。なお、吸収速度の測定は２回行ったが、２回目の注入（再吸収速度）は１回目の測定から１分後に行った。
【０１４３】
＜液戻り量の測定＞
吸収速度を測定後、１０分経過した吸収性シート上に、図１５に示すように、１５cm角の濾紙２４（東洋濾紙TYPE２）を１０枚重ね、更にその上に１５cm角のアクリル板２６と重り２２を、５０ｇ／cm² の荷重となる様に１分間かけ、その後濾紙２４を取り出し、濾紙２４に吸収された生理食塩水の重量を液戻り量とした。
【０１４４】
【表３】

【０１４５】
〔実施例７〕
吸収性物品の作製
図６に示す構成の生理用ナプキンを製造した。
即ち、吸収繊維シート１０として、長さ１７５ｍｍ、幅１４５ｍｍの吸収性シート（Ａ）を両側縁部が吸収体のほぼ中央で相対する様にＣ字状に折り曲げ圧縮し、幅７３ｍｍにした。この吸収シート（Ａ）を吸収体として使した。
防漏層３として、ポリラミ防水紙（長さ２０５ｍｍ、幅９５ｍｍ）を用い、かかるポリラミ防水紙で、吸収性シートの側面部及び底面部を被覆した。この吸収性シート１０とポリラミ防水紙との組み合わせ体の全ての面を、後述する液体吸収可能な表面層１（長さ２０５ｍｍ、幅１７２ｍｍ）により被覆し、且つ固定剤６として用いたホットメルト粘着剤によってこれらの部材を固定した。更に、上記表面層１の反対側に坪量３０ｇ／ｍ² 、幅２０ｍｍ、長さ１１５ｍｍのホットメルト粘着剤を粘着部４として２本塗工した。このようにして、図６に示す構成の生理用ナプキンを得た。
なお、上記表面層１としては、ポリエチレン開孔フィルムを用いた。この表面層１は、坪量３０ｇ／ｍ² のポリエチレンフィルムに開孔を施したものであり、一つの開孔径が０．５ｍｍで開孔面積率として２０％開孔しているものである。
【０１４６】
〔実施例８〜１０〕
吸収性物品の作製
実施例７で用いた吸収性シート（Ａ）の代わりに、それぞれ吸収性シート（Ｂ）〜（Ｄ）を用いる以外は、実施例７と同様にして、図６に示す構成の生理用ナプキンを得た。
【０１４７】
吸収性物品の作製
〔比較例６〜１０〕
実施例７で用いた吸収性シート（Ａ）の代わりに、それぞれ吸収性シート（Ｇ）〜（Ｋ）を用いる以外は、実施例７と同様にして、図６に示す構成の生理用ナプキンを得た。
【０１４８】
実施例７〜１０及び比較例６〜１０における生理用ナプキンについて、ポリマー固定化能及び吸収性能を評価するため、下記に示す方法によってポリマー脱落試験、製品厚み、吸収時間、動的液戻り量、漏れ試験を各生理用ナプキンについて行った。それぞれの結果を表４に示す。
【０１４９】
＜高吸収性ポリマーの脱落試験＞
実施例７〜１０及び比較例６〜１０の生理用ナプキンの重量を測定した後、これを長さ２８０mm×幅２００mmのチャック付きのポリ袋に入れ、この状態で５０回手で振りながら振動を加える。試験終了後、生理用ナプキンの重量変化を測定するとともに、ポリ袋中に脱落した高吸収性ポリマーが肉眼でよく観察できるよう、青色一号で染色した色水（０．３ｇ／水１００ml）をポリ袋中に加え、高吸収性ポリマーを膨潤させ、目視で脱落の程度を判定する。
○・・・高吸収性ポリマーの脱落が殆ど認められない。
△・・・高吸収性ポリマーの脱落が多少認められる。
×・・・高吸収性ポリマーの脱落がかなり認められる。
測定は１０回行い、その平均値をもって脱落量とする。
【０１５０】
＜製品厚さの測定＞
図１１に示すが如く、生理用ナプキンを１０枚重ね合わせ、その上方より重さ５００ｇのアクリル板を載せて１０枚分の厚さを測定し、１枚あたりの製品厚さを求めた。
【０１５１】
＜吸収時間（５ｇ）、再吸収時間（１０ｇ）、動的液戻り量の測定＞
図１２に示す吸収時間の測定装置を使用した。即ち、図１３に示す吸収性シート１００に代えて、実施例７〜１０及び比較例６〜１０で得られた生理用ナプキン３００を水平に置き、直径１ｃｍの注入口のついたアクリル板２０を載せ、この上に重り２２を載せて生理用ナプキン３００に５ｇ／cm² の荷重がかかるようした。
次いで、注入口から脱繊維馬血〔日本バイオテスト研究所（株）製〕５ｇを注入し、脱繊維馬血が完全に吸収されるまでの吸収時間（秒）を求める。脱繊維馬血が完全に吸収されてから、２０分間そのまま放置し、再び脱繊維馬血５ｇを注入し、再吸収時間（１０ｇ）を求め、同様に２０分間放置した。
その後、坪量３０ｇ／ｍ² で長さ１９５mm、幅７５mmの針葉樹クラフトパルプからなる吸収紙を１０枚、生理用ナプキンの上面（肌当接面側）に置き、図１３に示す可動式女性腰部モデル９０に、図１４に示すように生理用ナプキン８０を装着したショーツをはかせた後、１００秒／分（５０ｍ／分）の歩行速度で１分間歩行させた。
歩行終了後、生理用ナプキン８０及び吸収紙１０枚を取り出し、吸収紙に吸収された脱繊維馬血の重量を液戻り量（ｇ）として求めた。各々５点について測定し、それぞれの平均値を求め、吸収時間、再吸収時間及び動的液戻り量とした。
【０１５２】
＜漏れ試験（漏れ発生回数）＞
実施例７〜１０及び比較例６〜１０で得られた生理用ナプキン８０を、図１４に示す如く、可動式女性腰部モデル９０に装着させ、ショーツをはかせた後、１００歩／分（５０ｍ／分）の歩行速度で１０分間歩行させた。
次いで、歩行させながら、チューブ９１によって脱繊維馬血を生理用ナプキン８０に５ｇ注入した後、同じ速度で２０分間歩行させた時点（５ｇ吸収）、及びその後更に脱繊維馬血５ｇを注入した後同じ速度で２０分間歩行させた時点（１０ｇ吸収）、それぞれの時点でサンプル数１０枚中のうち、漏れが発生した枚数を数えた。
【０１５３】
【表４】

【０１５４】
表３及び表４に示す結果から明らかな様に、特定の吸収性シートを用いる本発明の吸収性物品は、従来の吸収性シート（水散布やエンボス一体化や接着剤による一体化で得られる吸収性シート）を有する吸収性物品に比べ、高吸収性ポリマーの固定性に優れ、且つ極薄の吸収性シートを用いた場合でも、吸収速度や液戻り量等の吸収特性に優れていることがわかる。
また、本発明の吸収性物品は、非常に簡単な構成であるにも拘わらず、液体の吸収時間が速く、液戻り量も少なく、しかも、漏れ発生回数の少ない、極めて高性能なものである。これは、本発明の吸収性物品に使用される吸収性シートが、その単一の構造に液体の吸収拡散勾配を有しているが故に、液体を素早く吸収し、吸収性シート中をスムーズに液体が透過し、しかも、液体が十分に拡散することによるものである。
【０１５５】
【発明の効果】
以上詳述した通り、本発明によれば、高吸収性ポリマーがシート内に確実に固定され、高吸収性ポリマーの脱落がほとんどなく、且つ高吸収性ポリマーのゲルブロッキングが起こり難い吸収性シートが得られる。該吸収性シートは、単一の構造中に液体の透過／拡散／保持という３つの機能を有し、吸収速度及び吸収力共に優れたものとなる。
【０１５６】
また、本発明の吸収性シートを製造するための好ましい方法によれば、従来の吸収性シートの製造方法に比して、製造プロセスが非常に高速化される。また、高吸収性ポリマーを固定するための複雑な加工プロセスが不要となり、製造プロセスが極めて簡略化される。
【０１５７】
また、上記製造方法によれば、高吸収性ポリマーを吸収性シートの全体に散布するのみでなく、長手方向に筋状に部分散布したり、或いは長手方向に間欠散布することもできるので、用途に応じて高吸収性ポリマーを散布する範囲を設定でき、より経済的に吸収性シートを製造できる。
【０１５８】
更に、本発明によれば、極めて薄いにもかかわらず、多量の高吸収性ポリマーが固定された極薄の吸収性物品を提供することができる。その上、該吸収性物品は、液体の吸収速度が高く、液戻り量が少なく、しかも漏れ発生数も少ないものである。特に、上記吸収性シートのみで吸収層を構成する場合には、１枚の吸収性シートのみをカットするだけで吸収性物品を製造することができ、極めて簡略な製造工程で吸収性物品を高速生産できる。また、上記吸収性シートは、一体化した構造を有しているので、該吸収性シートを具備する吸収性物品を着用して激しい運動等をした場合であっても高吸収性ポリマーが吸収性シートから分離して吸収性能が低下することもない。
【図面の簡単な説明】
【図１】 本発明の吸収性シートの好ましい一実施形態の断面を示す模式図である。
【図２】 本発明の吸収性シートを製造するために好ましく用いられる装置を示す概略図である。
【図３】 本発明の吸収性シートを製造するために好ましく用いられる装置を示す概略図である。
【図４】 本発明の吸収性物品の第１の実施形態としての生理用ナプキンの断面を示す概略図である。
【図５】 本発明の吸収性物品の第２の実施形態としての生理用ナプキンの断面を示す概略図である。
【図６】 本発明の吸収性物品の第３の実施形態としての生理用ナプキンの断面を示す概略図である。
【図７】 本発明の吸収性物品の第４の実施形態としての生理用ナプキンの断面を示す概略図である。
【図８】 本発明の吸収性物品の第５の実施形態としての生理用ナプキンの断面を示す概略図である。
【図９】 本発明の吸収性物品の第６の実施形態としての生理用ナプキンの断面を示す概略図である。
【図１０】 従来の吸収性シートの断面を示す模式図である。
【図１１】 生理用ナプキンの厚さの測定を表す模式図である。
【図１２】 吸収時間の測定を表す模式図である。
【図１３】 可動式女性腰部モデルを表す図である。
【図１４】 可動式女性腰部モデルの股部に生理用ナプキンを装着した状態を表す模式図である。
【図１５】 液戻り量の測定を表す模式図である。
【符号の説明】
１００ 吸収性シート
１０２ 吸収表面
１０５ 繊維集合体
１０６ 高吸収性ポリマー
１０８ 繊維ウエブ
３００ 吸収性物品[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an absorbent sheet particularly preferably used for sanitary napkins, hygiene pads, disposable diapers, medical pads, breast milk pads, drip sheets, kitchen absorbent sheets, household cleaning sheets, pet undersheets, etc. The present invention relates to a production method and an absorbent article using the same.
[0002]
[Prior art and problems to be solved by the invention]
Various methods for obtaining an absorbent sheet by fixing a superabsorbent polymer in an absorbent structure are known. For example, in US Pat. No. 3,070,095, as shown in FIG. 10, after superabsorbent polymer 16 is spread on tissue 30 and another tissue 31 is laminated thereon, a roller is used. It discloses the pressing of a superabsorbent polymer into a tissue by crimping. However, in this method, the superabsorbent polymer is only fixed in layers between the tissue layers, and a large amount of superabsorbent polymer cannot be fixed. Therefore, when such an absorbent sheet is used for an absorbent body of an absorbent article, for example, the superabsorbent 16 polymer is separated from the tissues 30 and 31 by the wearer's movement and the like, and between the tissues 30 and 31. Space may be created and liquid may stay.
[0003]
U.S. Pat. No. 3,670,731 discloses spraying a superabsorbent polymer between two paper layers and then embossing to secure the superabsorbent polymer in the embossed cavity. ing. However, this method also has the same drawbacks as the pressure bonding method using the roller.
[0004]
U.S. Pat. No. 3,670,731 discloses spreading a superabsorbent polymer between two crepe papers and then quilting to hold the superabsorbent polymer in place. Yes. However, this method still has the disadvantage that a large amount of superabsorbent polymer cannot be fixed.
[0005]
In Japanese Patent Publication No. 59-26467, Japanese Patent Laid-Open No. 54-123293, and Japanese Patent Laid-Open No. 54-141099, steam is sprayed on the tissue or water is sprayed thereon to wet the tissue. It is disclosed that the superabsorbent polymer is fixed between tissues by spraying the absorbent polymer to impart tackiness to the superabsorbent polymer. According to this method, although the superabsorbent polymer can be fixed to some extent, it cannot be completely prevented from falling off, and the fixing amount is still insufficient. Further, when the liquid is absorbed, the superabsorbent polymer swells in a layered manner, and in some cases, absorption inhibition due to gel blocking or the like may occur.
[0006]
JP-A-61-132697 discloses a method of producing an absorbent paper containing a superabsorbent polymer by spraying the superabsorbent polymer on the paper before drying in the paper making process and then drying the paper. Is described. According to this method, a certain amount of superabsorbent polymer can be fixed in paper, but the fixing amount is at most 10 g / m.²It is a degree, and it cannot be said that it is a sufficient amount. Further, in the obtained absorbent sheet, since the superabsorbent polymer exists also on the surface that absorbs the liquid, such a superabsorbent polymer is easily dropped by dynamic action including friction. It has the disadvantage that it does.
[0007]
Furthermore, a method is also known in which a hot melt adhesive is applied to the entire surface of a tissue or the like, and a superabsorbent polymer is fixed with the adhesive. According to this method, the superabsorbent polymer can be reliably fixed. However, since most of the surface of the superabsorbent polymer is covered with the hot melt adhesive, swelling inhibition of the superabsorbent polymer and liquid absorption are inhibited.
[0008]
As another method for fixing the superabsorbent polymer using a hot melt adhesive, there is a method of applying the hot melt adhesive in a spiral shape. According to this method, there is little swelling inhibition and absorption inhibition, and the highly absorbent polymer can be fixed efficiently. However, the manufacturing process and equipment are complicated by applying the hot melt adhesive in a spiral shape. Furthermore, since a large amount of the superabsorbent polymer is fixed in a layer, gel absorption of the superabsorbent polymer occurs when the liquid is absorbed, and the swelling of the liquid is inhibited.
[0009]
On the other hand, an absorptive sheet using wood pulp manufactured by a dry method is also known. In such an absorbent sheet, when an attempt is made to increase the sheet strength by using a chemical binder, a highly blended synthetic pulp, a low melting point synthetic fiber, or the like, the absorbent sheet becomes hydrophobic and the absorption rate decreases. If the sheet strength is low, when the liquid is absorbed, the superabsorbent polymer swells and breaks the absorbent sheet and protrudes outward. Further, in order to increase the surface strength of the absorbent sheet, crepe paper may be laminated, but in this case, there is a problem that the cost is increased. In addition, in any case, the superabsorbent polymer is not sufficiently fixed to the wood pulp, and the problem that the superabsorbent polymer easily falls off is not improved. Furthermore, when the absorbent sheet is strongly compressed, there is a problem that the liquid absorption rate is inevitably lowered.
[0010]
In addition to the above-described absorbent sheet, a method is also known in which a superabsorbent polymer is directly polymerized on a nonwoven fabric serving as a base material and is fixed on the nonwoven fabric to obtain an absorbent sheet. However, when a non-woven fabric made of hydrophilic fibers is used as the non-woven fabric, the superabsorbent polymer obtained as a result of the polymerization does not become particles and is fixed almost uniformly throughout the non-woven fabric. Has the disadvantage of lowering. On the other hand, when a nonwoven fabric made of hydrophobic fibers is used as the nonwoven fabric, unlike the nonwoven fabric made of hydrophilic fibers, the superabsorbent polymer obtained as a result of polymerization is in the form of particles, but the entire absorbent sheet Since it is hydrophobic, it has a disadvantage that the liquid absorption rate is slow. In addition, in these methods, the remaining unreacted monomer is unavoidable, so the use of the absorbent sheet is limited from the viewpoint of safety of the monomer to the human body.
[0011]
Accordingly, an object of the present invention is to provide an absorbent sheet in which the superabsorbent polymer is securely fixed without impairing the inherent absorption characteristics of the superabsorbent polymer.
[0012]
Another object of the present invention is to provide an absorbent sheet that can absorb liquid very smoothly without leaving it on the surface, can be quickly guided to the entire superabsorbent polymer, and can fix the liquid effectively. is there.
[0013]
Another object of the present invention is to provide an absorbent sheet in which the superabsorbent polymer does not cause gel blocking even when a liquid is repeatedly absorbed, and the inherent absorption characteristics of the superabsorbent polymer can be expressed.
[0014]
Moreover, the objective of this invention is providing the method which can manufacture the said absorbent sheet simply.
[0015]
Furthermore, the object of the present invention is to provide an absorbent article having a high absorbent performance, comprising the absorbent sheet.
[0016]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventors have conducted intensive studies and as a result, the fibers constituting the absorbent sheet are wetted, and the superabsorbent polymer is buried in the space formed between the fibers. In addition, by forming a layer of hydrophilic fine fibers or hydrophilic fine powder in the vicinity of the superabsorbent polymer, liquid diffusibility near the interface of the superabsorbent polymer is improved and the high absorbency polymer is increased. It has been found that the liquid immobilization effect of the absorbent polymer is improved and the gel blocking is effectively prevented.
[0017]
  The present invention has been made based on the above knowledge, and is an absorbent sheet including at least a superabsorbent polymer, a bulky cellulose fiber, and a hydrophilic fine fiber or a hydrophilic fine powder,
  The absorbent sheet is composed of a fiber assembly and a fiber web, and the fiber assembly and the fiber web are integrated.
  The fiber assembly has an absorption surface and does not contain the superabsorbent polymer on the absorption surface side, andAbove average fiber length 1-20mmMainly bulky cellulose fiber,
  The fiber web isAbove average fiber length 1-20mmMainly bulky cellulose fiber,
  The superabsorbent polymer is contained in the absorbent sheet and adhered to the fibers constituting the absorbent sheet.
  The hydrophilic fine fiber orthe aboveHydrophilic fine powderThe average fiber length or average powder particle size is 0.02 to 0.5 mmThe above object is achieved by providing an absorbent sheet characterized in that it is mainly contained in a region where the superabsorbent polymer exists.
[0018]
  Further, the present invention provides a preferable method for producing the absorbent sheet,
  at leastthe aboveA superabsorbent polymer is sprayed on a wet fiber web containing bulky cellulose fibers, and at the same time as or before or after the spraying of the superabsorbent polymer.the aboveHydrophilic fine fibers orthe aboveSprinkle with hydrophilic fine powder,
  On top of which the above fiber assembly is superposed, and
  The manufacturing method of the absorptive sheet | seat characterized by including the process of drying and integrating these is provided.
[0019]
  Further, the present invention provides an absorbent article having a liquid-absorbable surface layer, a liquid-retaining absorbent layer, and a liquid-impermeable leak-proof layer as a preferred absorbent article using the absorbent sheet,
  An absorbent sheet containing at least a superabsorbent polymer, bulky cellulose fibers, and hydrophilic fine fibers or hydrophilic fine powders on the surface layer, the absorbent layer, or the absorbent layer side of the leak-proof layer. Is included,
  The absorbent sheet is composed of a fiber assembly and a fiber web, and the fiber assembly and the fiber web are integrated.
  The fiber assembly has an absorption surface and does not contain the superabsorbent polymer on the absorption surface side, andAbove average fiber length 1-20mmMainly bulky cellulose fiber,
  The fiber web isAbove average fiber length 1-20mmMainly bulky cellulose fiber,
  The superabsorbent polymer is contained in the absorbent sheet and adhered to the fibers constituting the absorbent sheet.
  The hydrophilic fine fiber orthe aboveHydrophilic fine powderThe average fiber length or average powder particle size is 0.02 to 0.5 mmThe present invention provides an absorbent article that is mainly contained in a region where the superabsorbent polymer exists.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the absorbent sheet of the present invention will be described in detail with reference to the drawings. Here, FIG. 1 is a schematic view showing a cross section of a preferred embodiment of the absorbent sheet of the present invention.
[0021]
As shown in FIG. 1, the absorbent sheet 100 of the present invention includes at least a superabsorbent polymer 106, bulky cellulose fibers 12, and hydrophilic fine fibers 14 or hydrophilic fine powders 14. The absorbent sheet 100 is composed of a fiber assembly 105 and a fiber web 108. The fiber assembly 105 has an absorption surface 102 and does not contain a superabsorbent polymer on the absorption surface 102 side. The fiber assembly 105 is mainly composed of bulky cellulose fibers 12.
[0022]
On the other hand, the fiber web 108 is mainly composed of bulky cellulose fibers 12 as shown in FIG.
[0023]
Further, as shown in FIG. 1, the fiber assembly 105 and the fiber web 108 are integrated. Further, the superabsorbent polymer 106 is contained in the absorbent sheet 100 and is bonded to the fibers constituting the absorbent sheet 100.
[0024]
Further, as shown in FIG. 1, the hydrophilic fine fiber 14 or the hydrophilic fine powder 14 is mainly contained in a region where the superabsorbent polymer 106 exists, and the superabsorbent polymer 106. A layer of the hydrophilic fine fiber 14 or the hydrophilic fine powder 14 is formed in the vicinity of.
[0025]
As described above, the first absorbent sheet 100 of the present invention includes the fiber assembly 105 and the fiber web 108, the superabsorbent polymer 106 is included therein, and the hydrophilic fine fibers 14 or the hydrophilic fibers. One of the characteristics is that the fine powder 14 has an integral structure mainly contained in the region where the superabsorbent polymer 106 exists. More specifically, the absorbent sheet 100 of the present invention has mechanical entanglement between the fibers constituting the fiber assembly 105 and the fibers constituting the fiber web 108, hydrogen bonding (and strong auxiliary agent), and heat. The fiber assembly 105 and the fiber web 108 are integrated by fusion or the like. By having such a structure, the superabsorbent polymer 106 can be reliably fixed and prevented from falling off. In addition, the permeability of the liquid absorbed from the absorbing surface 102 is further improved, and it smoothly reaches the superabsorbent polymer 106 and diffuses effectively near the interface between the superabsorbent polymers 106. In addition, gel blocking of the superabsorbent polymer 106 that has absorbed the liquid can be suppressed. Therefore, the first absorbent sheet 100 of the present invention has a completely different structure from the conventional absorbent sheet (FIG. 10) in which the superabsorbent polymer is sandwiched between the two absorbent papers in layers (that is, The conventional absorbent sheet is 2 plies, but the first absorbent sheet 100 of the present invention is a single sheet). Such integration is preferably achieved by superposition by wet papermaking as described later.
[0026]
Hereinafter, the fiber assembly 105 and the like having the absorbent surface 102 constituting the absorbent sheet 100 of the present invention will be described in detail.
[0027]
First, the fiber assembly 105 having the absorption surface 102 will be described.
Here, the above “absorbing surface” refers to a surface that first absorbs liquid mainly when the absorbent sheet 100 of the present invention absorbs liquid. That is, when the absorbent sheet 100 of the present invention is used, the liquid is mainly absorbed from the fiber assembly 105 side.
[0028]
The fiber assembly 105 does not include the superabsorbent polymer 106 on the absorption surface 102 side. Here, “not including the superabsorbent polymer” does not mean that the fiber assembly 105 does not include the superabsorbent polymer 106 at the side of the absorbing surface 102 at all, A trace amount of superabsorbent polymer inevitably mixed in the method for producing an absorbent sheet means that it is acceptable but substantially free of superabsorbent polymer.
[0029]
The fiber aggregate 105 is mainly composed of the bulky cellulose fiber 12 and is obtained by mechanical entanglement, physical entanglement, thermal bonding, or the like of the fiber. For example, paper or nonwoven fabric can be used. . As the paper, paper obtained by wet papermaking or creped paper can be used. On the other hand, as the nonwoven fabric, various nonwoven fabrics such as a card method nonwoven fabric, a spunbond nonwoven fabric, and a spunlace nonwoven fabric mainly composed of synthetic cellulose fibers such as rayon and cupra and natural cellulose fibers such as cotton can be used.
[0030]
The fiber assembly 105 is mainly composed of bulky cellulose fibers 12 as described above. Although details of the bulky cellulose fiber will be described later, the bulky cellulose fiber is preferably contained in an amount of 30 parts by weight or more based on 100 parts by weight of the fiber assembly, and more preferably 50 to 98 parts by weight. included.
[0031]
The fiber assembly is preferably given wet strength. This is because by imparting the wet strength, the form can be stably maintained even when the absorbent sheet of the present invention is moistened. The wet strength of the fiber assembly is preferably 50 g or more, and more preferably 100 g or more, when measured by JIS-P-8113. In order to impart wet strength to the fiber assembly, wood pulp or non-wood pulp may be blended, hot-melt adhesive fibers may be blended, or a strong auxiliary agent (paper strength reinforcing agent) may be blended. preferable.
The details of the hot-melt adhesive fiber will be described later, but the hot-melt adhesive fiber is preferably contained in an amount of 1 to 50 parts by weight based on 100 parts by weight of the fiber assembly, and more preferably 3 to 30 parts by weight. Part included.
In addition, as the strong auxiliary agent, polyamine / epichlorohydrin resin, dialdehyde starch, sponge, carboxymethyl cellulose and the like can be used. The strong auxiliary agent is preferably contained in an amount of 0 to 30 parts by weight, more preferably 0 to 20 parts by weight, based on 100 parts by weight of the fiber assembly.
[0032]
The basis weight of the fiber assembly is 10 to 200 g / m.²It is preferably 10 to 100 g / m.²More preferably, it is 20-60 g / m.²It is more preferable that The basis weight is 10 g / m²If it is less than 1, the superabsorbent polymer may protrude from the fiber assembly and fall off when the superabsorbent polymer swells. On the other hand, the basis weight is 200 g / m.²If it exceeds 1, the density of the fiber assembly will increase too much, and the absorbent sheet may become too hard, so it is preferable to be within the above range.
[0033]
The fiber assembly 105 may be manufactured in advance before manufacturing a fiber web 108 to be described later, and when the absorbent sheet 100 of the present invention is manufactured, it is manufactured at the same time as the fiber web 108. Also good.
[0034]
Next, the superabsorbent polymer 106 contained in the absorbent sheet 100 of the present invention will be described.
As shown in FIG. 1, the superabsorbent polymer 106 is included in the absorbent sheet 100 of the present invention, and is dispersed in a space formed between the fibers constituting the absorbent sheet 100 of the present invention. ing. More specifically, as shown in FIG. 1, the superabsorbent polymer 106 is mainly contained in a fiber web 108 described later, and is formed in a space formed between fibers constituting the fiber web 108. It is preferably dispersed. As a result, the superabsorbent polymer 106 is reliably fixed in the absorbent sheet 100 of the present invention and the occurrence of gel blocking is suppressed. Here, “the superabsorbent polymer 106 is contained in the absorbent sheet 100” means that the superabsorbent polymer 106 does not exist at all on the surface of the absorbent sheet 108 of the present invention. However, in the preferable production method of the absorbent sheet of the present invention, which will be described later, a small amount of the superabsorbent polymer inevitably present on the surface of the absorbent sheet is allowed, and most of the superabsorbent polymer 106 described above is allowed. Is present inside the absorbent sheet 100 of the present invention.
[0035]
The superabsorbent polymer 106 is bonded to the fibers constituting the absorbent sheet 100 of the present invention, preferably the fibers constituting the fiber web 108. Accordingly, the superabsorbent polymer 106 is more firmly fixed, and the gel blocking is further suppressed. Here, it is not necessary for the superabsorbent polymer 106 to have all the particles adhered to the fibers. Based on the total amount of the superabsorbent polymer 106, 50% by weight or more is preferably bonded to the fiber, and particularly 70% by weight or more is preferably bonded to the fiber. If the amount of adhesion of the superabsorbent polymer 106 is less than 50% by weight, the immobilization effect may not be sufficiently exhibited, which is not preferable. The method for adhering the superabsorbent polymer 106 to the fiber will be described later.
[0036]
In addition, when the superabsorbent polymer 106 is a particle agglomeration type superabsorbent polymer in which spherical polymers are agglomerated as primary particles to form secondary particles, all of the primary particles adhere to the fibers. If the secondary particles are partly adhered to the fiber, the superabsorbent polymer is fixed to the fiber.
[0037]
Preferably, the superabsorbent polymer 106 is not dispersed in layers in the absorbent sheet 100 of the present invention, but is three-dimensionally dispersed as shown in FIG. Therefore, a superabsorbent polymer can be dispersed in a large amount. That is, the upper limit of the spreading basis weight of the superabsorbent polymer in the conventional absorbent sheet in which the superabsorbent polymer is dispersed in a layered form (that is, two-dimensional) is generally about 50 to 100 g / m.²In contrast, in the absorbent sheet 100 of the present invention, the superabsorbent polymer 106 can be dispersed three-dimensionally, so the upper limit of the spraying basis weight of the superabsorbent polymer 106 is about 200 to 300 g / m²And the spreading basis weight of the superabsorbent polymer 106 can be increased to about three times that of the conventional absorbent sheet. Therefore, the absorbent sheet 100 of the present invention dramatically increases the amount of liquid absorbed as compared to the conventional absorbent sheet. Furthermore, since the superabsorbent polymer 106 is dispersed three-dimensionally, the original absorbent performance of the superabsorbent polymer 106 is more effectively expressed. That is, even when the same amount of superabsorbent polymer as that of the conventional absorbent sheet is used, the absorption performance can be further improved and the absorbent sheet can be made extremely thin. In addition, since the spreading basis weight can be increased, it can be suitably used as an absorbent body such as a paper diaper that requires a large absorption capacity.
[0038]
The superabsorbent polymer 106 has a spreading basis weight of 1 to 300 g / m.²Is preferably 5 to 300 g / m.²More preferably, it is 10 to 200 g / m.²More preferably, it is 20-150 g / m.²It is particularly preferred that The spreading basis weight is 1 g / m²If it is less than 1, water absorption is insufficient and sufficient functions cannot be exhibited. On the other hand, the spreading basis weight is 300 g / m.²If it is more, the adhesive force between the fiber web 108 and the fiber assembly 105 is reduced, and the superabsorbent polymer 106 is likely to fall off.
[0039]
As the superabsorbent polymer 106, a polymer that can absorb and retain a liquid 20 times or more its own weight and can be gelled is preferable. Examples of such superabsorbent polymers include polyacrylic acid and salts thereof, and polyacrylate graft polymers such as starch, crosslinked carboxylmethylated cellulose, polymers or copolymers of acrylic acid or alkali metal acrylates. Coalescence can be mentioned. As the polyacrylic acid salt, a sodium salt can be preferably used. In addition, a comonomer such as maleic acid, itaconic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2-hydroxyethyl (meth) acrylate or styrenesulfonic acid is added to acrylic acid. Copolymers copolymerized within a range that does not deteriorate the performance of the superabsorbent polymer can also be preferably used.
[0040]
Next, the hydrophilic fine fiber 14 or the hydrophilic fine powder 14 mainly contained in the region where the superabsorbent polymer 106 exists will be described.
As shown in FIG. 1, the hydrophilic fine fiber 14 or the hydrophilic fine powder 14 is mainly contained in the vicinity of the superabsorbent polymer 106 in the absorbent sheet of the present invention. A layer different from 108 is formed. Since the hydrophilic fine fibers 14 and the hydrophilic fine powder 14 have a large surface area, the liquid diffusibility is increased by capillary action. As a result, the liquid diffusion near the interface between the superabsorbent polymers 106 is increased. Improves. Moreover, since the hydrophilic fine fibers 14 or the hydrophilic fine powders 14 are present between the superabsorbent polymers, gel blocking of the superabsorbent polymer 106 that has swelled by absorbing liquid is also effective. Is prevented.
[0041]
The hydrophilic fine fiber or the hydrophilic fine powder has a spreading basis weight of 1 to 300 g / m.²Is preferably 5 to 200 g / m.²More preferably, it is 5 to 150 g / m.²It is more preferable that The spreading basis weight is 1 g / m²If it is less than 1, the diffusion of the liquid in the vicinity of the superabsorbent polymer may not be performed effectively, or the gel blocking of the superabsorbent polymer may not be effectively prevented. On the other hand, the spreading basis weight is 300 g / m.²Exceeds the density of the fine fiber or fine powder in the vicinity of the superabsorbent polymer, the liquid transfer to the superabsorbent polymer is reduced, or the absorbent sheet becomes too hard. In some cases, it is preferable to be within the above range.
[0042]
The hydrophilic fine fiber or the hydrophilic fine powder has a fiber roughness of less than 0.1 mg / m or a fiber roughness of less than 0.3 mg / m and a perfect circle of the fiber cross section. The degree is preferably 0.01 to 0.5. Hydrophilic fine fibers or hydrophilic fine powders having such physical property values are preferable because of their high specific surface area. The method for measuring the fiber roughness will be described later.
[0043]
  The hydrophilic fine fiber or hydrophilic fine powder has an average fiber length or an average powder particle size of 0.02 to 0.5 mm.. SoTo increase the specific surface area of,The average fiber length or average particle size is 0.1 to 0.3 mmPreferGood.
[0044]
Furthermore, the hydrophilic fine fiber or hydrophilic fine powder is preferably crosslinked. By using a crosslinked product, it is possible to suppress the fine fibers or fine powder itself from absorbing and swelling the liquid, so that the distance between the fibers (powder) does not change even when wet, and the liquid is transferred. It is preferable because the property does not deteriorate. Further, when a large amount of the fine fibers or fine powder is dispersed, it is preferable because the density of the fine fibers or fine powder in the vicinity of the superabsorbent polymer can be prevented from becoming too high. Examples of such fine fibers and fine powders include crosslinked cellulose fibers, cellulose powders, and hydrophilic synthetic fibers.
[0045]
Specific examples of the hydrophilic fine fibers or hydrophilic fine powders include cellulose fibers and cellulose powders such as pulp, cotton and rayon; hydrophilic synthetic fibers such as polyacrylonitrile and polyvinyl alcohol; kaolin, bentonite and hydro Examples thereof include inorganic fibers such as talcite and inorganic powder. These hydrophilic fine fibers and the hydrophilic fine powder can be used alone or in admixture of two or more. Furthermore, the hydrophilic fine fiber and the hydrophilic fine powder can be mixed and used.
[0046]
A commercially available thing can also be used as said hydrophilic fine fiber and said hydrophilic fine powder. For example, pulp flocs (trade name) manufactured by Sanyo Kokusaku Pulp Co., Ltd., which are beaten wood pulp such as softwood pulp and hardwood pulp, then mechanically pulverized and then separated by a sieve of 0.5 mm or less, etc. It is done. As another example, cellulose fiber such as wood pulp is mechanically pulverized, then hydrolyzed with acid, and further mechanically pulverized cellulose fine fiber (powder) [manufactured by Sanyo Kokusaku Pulp Co., Ltd. KC Flock (trade name) and Avicel (trade name) manufactured by Asahi Kasei Kogyo Co., Ltd.]. Moreover, as a commercially available inorganic fine fiber, hydrous magnesium silicate fiber [ate plus ML-30 (trade name) manufactured by Mizusawa Chemical Co., Ltd.] and the like can be mentioned. Among these commercially available products, cellulose fine fibers and fine cellulose powder obtained by pulverizing and refining pulp can be obtained more inexpensively and preferably used.
[0047]
Next, the fiber web 108 in the absorbent sheet 100 of the present invention will be described.
[0048]
In the present invention, the “fiber web” means that the constituent fibers are not restrained at all in a wet state before polymer dispersion, or are slightly restrained by hydrogen bonds, mechanical entanglement, frictional force, etc. In a state having a high degree of freedom, and after the drying, the constituent fibers are strongly bound to each other and take a sheet-like form.
[0049]
The fiber web 108 is in a wet state before the superabsorbent polymer 106 is sprayed, and it is important that the fibers constituting the fiber web 108 have a very high degree of freedom. By dispersing the superabsorbent polymer 106 on the fiber web 108 in such a state, the superabsorbent polymer 106 is embedded and fixed in the fiber web 108. That is, the superabsorbent polymer 106 is three-dimensionally dispersed in the fiber web 108. Further, the fiber web 108 has such a strength that the superabsorbent polymer 106 does not precipitate on the surface of the first absorbent sheet 100 after the fiber web 108 and the fiber assembly 105 are integrated. It is also important that For this purpose, the fiber web 108 preferably has a tensile strength measured according to JIS-P-8113 of 50 g or more, and more preferably 100 g or more. In order to impart wet strength to the fiber web 108, the fiber web 108 is blended with normal cellulose fibers capable of forming hydrogen bonds, that is, wood pulp, non-wood pulp, etc. It is preferable to blend a meltable adhesive fiber or the above-mentioned strong auxiliary agent.
[0050]
The fiber web 108 is preferably formed from at least the bulky cellulose fiber. The bulky cellulose fiber is preferably contained in an amount of 30 parts by weight or more, more preferably 50 to 99 parts by weight, based on 100 parts by weight of the fiber web. In addition, as said bulky cellulose fiber, the thing similar to what is used for the said fiber assembly 105 can be used preferably, The detail is mentioned later.
The fiber web 108 is particularly preferably formed by the same composition as the fibers and components that form the fiber assembly 105.
[0051]
The basis weight of the fiber web 108 is preferably 10 to 200 g / m.²And more preferably 10 to 100 g / m²It is. The basis weight is 10 g / m²Otherwise, the superabsorbent polymer 106 may protrude from the fiber web 108 and fall off when the superabsorbent polymer 106 swells. On the other hand, the basis weight is 200 g / m.²Since the density of a fiber web will rise too much and the said absorbent sheet 100 may become hard too much, it is preferable to set it as the said range.
[0052]
In the absorbent sheet of the present invention, the basis weight of the fiber assembly is 10 to 200 g / m.²The spraying basis weight of the superabsorbent polymer is 1 to 300 g / m.²The application basis weight of the hydrophilic fine fiber or hydrophilic fine powder is 1 to 300 g / m.²And the basis weight of the fiber web is 10 to 200 g / m.²It is preferable that the basis weight of the fiber assembly is 10 to 100 g / m.²The scattering basis weight of the superabsorbent polymer is 10 to 200 g / m.²The spraying basis weight of the hydrophilic fine fiber or hydrophilic fine powder is 5 to 200 g / m.²And the basis weight of the fiber web is 10 to 100 g / m²More preferably.
[0053]
The total basis weight of the absorbent sheet of the present invention is 22 to 500 g / m.²Preferably, it is 30 to 300 g / m²More preferably, it is 50 to 200 g / m.²It is more preferable that
[0054]
Furthermore, the absorbent sheet of the present invention is 2.5 g / cm.²The thickness under load is preferably 0.3 to 5 mm, and more preferably 0.5 to 3 mm. In the case of an ultrathin absorbent sheet, 2.5 g / cm²The thickness under load is preferably 0.3 to 1.5 mm, and more preferably 0.3 to 1.2 mm.
[0055]
  Next, the bulky cellulose fiber and hot-melt adhesive fiber used for the absorbent sheet of the present invention will be described.
  First, the bulky cellulose fiber will be described. As the bulky cellulose fiber, any cellulose fiber may be used as long as it is bulky. As the cellulose fiber, for example, natural cellulose such as wood pulp and cotton, and regenerated cellulose such as rayon and cupra can be used. From the viewpoint of cost, wood pulp is preferably used, and conifer kraft pulp is particularly preferably used. These cellulose fibers can use 1 type (s) or 2 or more types. The average fiber length of the bulky cellulose fiberIs1-20mmThe
  In the present invention, “bulky fiber” means that the fiber shape has a three-dimensional structure such as a twisted structure, a crimped structure, a bent and / or branched structure, or the fiber cross section is very thick (for example, the fiber roughness is 0. 0). 3 mg / m or more).
[0056]
Examples of preferable bulky cellulose fibers include cellulose fibers having a fiber roughness of 0.3 mg / m or more. Such cellulose fibers are preferable because the cellulose fibers are accumulated in a bulky state and the bulky network structure is easily formed. Further, it is preferable because the liquid movement resistance is small and the liquid passage speed is high. In addition to the fiber roughness being 0.3 mg / m or more, cellulose fibers having a fiber cross-section roundness of 0.5 to 1 are more preferable because the above effects are further exhibited.
[0057]
In the present invention, the “fiber roughness” is used as a scale representing the thickness of fibers in fibers with non-uniform fiber thickness, such as wood pulp. For example, a fiber roughness meter ( FS-200, manufactured by KAJANNI ELECTRONICS LTD.).
[0058]
Examples of cellulose fibers with a fiber roughness of 0.3 mg / m or more include softwood kraft pulp (“ALBACEL” (trade name) manufactured by Federal Paper Board Co. and “INDORAYON” (trade name) manufactured by PT Inti Indorayon Utama. )] And the like.
[0059]
As described above, in the present invention, it is preferable to use wood pulp as the cellulose fiber, but in general, the cross section of the wood pulp is flattened by delignification treatment, and most of its roundness is less than 0.5. is there. In order to make the roundness of such wood pulp 0.5 or more, for example, if the wood pulp having a fiber roughness of 0.3 mg / m or more is mercerized to swell the cross section of the wood pulp Good. That is, the bulky cellulose fiber is preferably mercerized pulp.
[0060]
Thus, as the cellulose fiber having a roundness of the fiber cross section of 0.5 to 1, a mercerized pulp having a roundness of 0.5 to 1 obtained by mercerizing wood pulp is preferable. Examples of commercially available mercerized pulp that can be used in the present invention include “FILTRANIER” (trade name) manufactured by ITT Rayonier Inc. and “POROSANIER” (trade name) manufactured by the same company.
[0061]
As described above, with respect to the fiber roughness, the bulky cellulose fiber preferably has a fiber roughness of 0.3 mg / m or more, more preferably a fiber roughness of 0.3 to 2 mg / m, A more preferable fiber roughness is 0.32-1 mg / m. The roundness of the fiber cross section is more preferably 0.55 to 1.
[0062]
Other preferable examples of the bulky cellulose fiber include a crosslinked cellulose fiber obtained by cross-linking cellulose molecules within and between molecules. Such a crosslinked cellulose fiber is preferable because it does not swell even when wet with a liquid, has little twist / sag, and further maintains a bulky structure without lowering its strength.
[0063]
Although there is no restriction | limiting in particular in the method for bridge | crosslinking a cellulose fiber, For example, the crosslinking method using a crosslinking agent is mentioned. Examples of such crosslinking agents include N-methylol compounds such as dimethylolethyleneurea and dimethyloldihydroxyethyleneurea; polycarboxylic acids such as citric acid, tricarballylic acid and butanetetracarboxylic acid; polyols such as dimethylhydroxyethyleneurea A cross-linking agent for polyglycidyl ether compounds. In particular, a crosslinking agent of a polycarboxylic acid or a polyglycidyl ether compound that does not generate formalin or the like harmful to the human body during crosslinking is preferable.
[0064]
The amount of the crosslinking agent used is preferably 0.2 to 20 parts by weight with respect to 100 parts by weight of the cellulose fiber. If the amount used is less than 0.2 parts by weight, the crosslink density of the cellulose fibers is low, so the elastic modulus may be greatly reduced when wet. If the amount used exceeds 20 parts by weight, the cellulose fibers Since the cellulose fiber may become brittle when it becomes too rigid and stress is applied, the above range is preferable.
[0065]
In order to cross-link the cellulose fiber using the cross-linking agent, for example, the cellulose fiber is impregnated into an aqueous solution of the cross-linking agent, if necessary, and the aqueous solution of the cross-linking agent and the design adhesion amount. The cellulose fiber is dehydrated, and then heated to the crosslinking temperature, or an aqueous solution of a crosslinking agent is sprayed on the cellulose fiber so as to have a designed adhesion amount by spraying, and then heated to the crosslinking temperature and crosslinked. React.
[0066]
In addition, a commercially available thing can also be used as said crosslinked cellulose fiber. Examples of such crosslinked cellulose fibers include “High Bulk Additive” manufactured by Weyerhaeuser Paper Co.
[0067]
Further preferred cross-linked cellulose fibers are those having a fiber roughness of 0.3 mg / m or more and a roundness of the fiber cross section of 0.5 to 1. Furthermore, the crosslinked cellulose fiber whose roundness of a fiber cross section is 0.5-1 is also preferable. Furthermore, the above-mentioned crosslinked cellulose fibers of mercerized pulp are also preferable.
[0068]
Next, the said hot-melt-adhesive fiber used arbitrarily in this invention is demonstrated.
As the hot-melt adhesive fibers, fibers that are melted by heating and bonded to each other can be used. Specifically, for example, polyolefin fibers such as polyethylene, polypropylene, and polyvinyl alcohol, polyester fibers, and polyethylene-polypropylene. Examples thereof include a composite fiber, a polyethylene-polyester composite fiber, a low melting point polyester-polyester composite fiber, a polyvinyl alcohol-polypropylene composite fiber having a hydrophilic fiber surface, and a polyvinyl alcohol-polyester composite fiber. When using a composite fiber, any of a core-sheath type composite fiber and a side-by-side type composite fiber can be used. These hot-melt adhesive fibers can be used alone or in combination of two or more. Examples of the hot-melt adhesive fiber preferably used in the present invention include polyvinyl alcohol and polyester.
[0069]
The hot-melt adhesive fibers generally have a fiber length of 2 to 60 mm and a fiber diameter of 0.5 to 3 denier.
[0070]
In the absorbent sheet 100 of the present invention having the configuration as described above, the single structure has a liquid diffusion gradient. More specifically, the absorbent surface 100 side of the absorbent sheet 100 is mainly composed of the above bulky cellulose fibers, so that the liquid has high permeability and there is little liquid residue on the absorbent surface 102. The absorbed liquid is quickly transferred to the superabsorbent polymer 106, and a layer formed from the hydrophilic fine fiber or hydrophilic fine powder having a particularly high diffusibility (that is, the superabsorbent polymer). In the existing region), the liquid diffusibility is increased by the capillary phenomenon of the hydrophilic fine fiber or the hydrophilic fine powder, and as a result, the liquid diffusibility near the interface between the superabsorbent polymers is increased. improves. As described above, the absorbent sheet 100 has a liquid permeation / diffusion / fixation function in a single structure, so that the liquid can be fixed with the superabsorbent polymer 106 more quickly and reliably. Can do. And since the said hydrophilic fine fiber or hydrophilic fine powder exists between each superabsorbent polymer particle, the gel blocking of this superabsorbent polymer can also be prevented effectively.
[0071]
In the absorbent sheet of the present invention, other layers may be further integrated as necessary.
[0072]
  Next, a preferable method for producing the absorbent sheet of the present invention will be described.
  The absorbent sheet of the present invention is at leastthe aboveA superabsorbent polymer is sprayed on a wet fiber web containing bulky cellulose fibers, and at the same time as or before or after the spraying of the superabsorbent polymer.the aboveHydrophilic fine fibers orthe aboveA process of spraying hydrophilic fine powder;
  A step of superimposing the fiber assembly thereon,
  And drying and integrating them.
[0073]
Each of these steps will be described below.
[0074]
First, a fiber web containing at least bulky cellulose fibers is formed. There is no restriction | limiting in particular in the method of forming the said fiber web, For example, although a dry papermaking method etc. can be used, Preferably a wet papermaking method is used. This is because, as will be described later, when the superabsorbent polymer is sprayed onto the fiber web, the fiber web must be wet and the fiber has a very high degree of freedom. This is because if the web is formed, it immediately realizes a wet state, so that the labor of making the wet state in a separate process can be saved. In addition, since the fiber web obtained by the wet papermaking method is not sufficiently bonded to each other before drying, when the superabsorbent polymer is sprayed in that state, the superabsorbent polymer is not interfibered. It is easy to embed three-dimensionally in the space formed, and has a merit that a large amount of superabsorbent polymer can be dispersed.
[0075]
When wet papermaking the fiber web, the fibers and components that form the fiber web, preferably the bulky cellulose fiber, the hot-melt adhesive fiber, the strong auxiliary agent, and the like are brought to a predetermined concentration. Then, it is dispersed in water to form a slurry. The concentration of the bulky cellulose fiber, the hot-melt adhesive fiber, and the strong auxiliary agent in the slurry may be the concentration in general wet papermaking. Further, the relative blending ratio between the hydrophilic fiber, the hot-melt adhesive fiber, the strong auxiliary agent, etc. is adjusted so that the blending ratio in the fiber web obtained by wet papermaking is in the above-mentioned range. That's fine.
[0076]
In the wet state, the superabsorbent polymer is sprayed on the fiber web thus obtained. The wet state of the fiber web is preferably about 20 to 500 parts by weight of water based on 100 parts by weight of the dry fiber web, and more preferably contains 50 to 300 parts by weight of water. If the amount of water is less than 20 parts by weight, the sprayed superabsorbent polymer absorbs water and becomes wet and cannot obtain tackiness. If the amount exceeds 500 parts by weight, the superabsorbent polymer will be excessively absorbed, resulting in poor drying in the drying step described later.
[0077]
The superabsorbent polymer is dispersed on a wet fiber web. As a result, the superabsorbent polymer absorbs water and becomes sticky, and is buried in the fibers constituting the fiber web, and is bonded and fixed to the fibers. Further, since the fiber web in a wet state has a degree of freedom because the fibers constituting it are not yet bonded to each other, the superabsorbent polymer can be dispersed three-dimensionally. Therefore, a larger amount of the superabsorbent polymer can be stably fixed as compared with the conventional absorbent sheet. When the superabsorbent polymer is sprayed, the superabsorbent polymer may be sprayed uniformly on the entire surface of the wetted fiber web or, if necessary, spaced in the longitudinal direction of the wetted fiber web. In addition, it can be partially sprayed in a streak shape, or can be intermittently sprayed in a shot shape in the longitudinal direction of the wet fiber web.
[0078]
Furthermore, the hydrophilic fine fiber or the hydrophilic fine powder is sprayed at the same time as the superabsorbent polymer or before or after. Thus, the hydrophilic fine fiber or hydrophilic fine powder can be mainly present in the region where the superabsorbent polymer exists, and the hydrophilic fine fiber or hydrophilic fine powder A layer can be formed. As a result, the liquid diffusibility in the vicinity of the interface of the superabsorbent polymer is improved, the liquid immobilization effect of the superabsorbent polymer is improved, and the gel blocking is effectively prevented.
[0079]
When spraying the hydrophilic fine fiber or hydrophilic fine powder, it may be sprayed uniformly over the entire surface of the fiber web, as with the superabsorbent polymer, or as necessary. It is also possible to partially scatter the fiber web in the longitudinal direction at intervals in the longitudinal direction, or to spray intermittently in the longitudinal direction of the wet fiber web. Preferably, the dispersion state of the hydrophilic fine fiber or the hydrophilic fine powder is the same as the dispersion state of the superabsorbent polymer.
[0080]
Next, the fiber assembly is superposed on the surface of the fiber web on which the superabsorbent polymer and the hydrophilic fine fibers or hydrophilic fine powder are dispersed. At this point, since the fibers in the fiber web still have a degree of freedom, the superabsorbent polymer is embedded in the fiber web and the fibers in the fiber web and the fiber assembly. Easily intertwine with other fibers.
[0081]
Subsequently, by drying the laminated body of the fiber web and the fiber assembly, the fibers are entangled with each other, and further, an action of hydrogen bonding or heat fusion is added, and the fiber web and the fiber assembly are Are integrated to obtain the absorbent sheet of the present invention. Although drying temperature is based also on the kind of fiber etc. to be used, it is preferable that it is the range of 100-180 degreeC, and the more preferable drying temperature is the range of 105-150 degreeC. By drying and integration, the fiber web and the fiber assembly are integrated, and the fibers constituting the fiber web are bonded together to form a sheet. In addition, there is no restriction | limiting in particular in a drying means, For example, a Yankee dryer, an air through dryer, etc. can be used.
[0082]
Particularly preferably, the absorbent sheet of the present invention is produced by an in-line single process using a wet paper machine. That is, as shown in FIGS. 2 and 3, the fiber web 108 is formed by the forming part 40 of the wet paper machine, the fiber web 108 is dehydrated in the suction dewatering step 42, and then the high web is formed on the fiber web 108. The absorbent polymer 106 is sprayed, and the hydrophilic fine fiber 14 or the hydrophilic fine powder 14 is sprayed at the same time as or before and after the spraying of the superabsorbent polymer 106, and the fiber aggregate is further sprinkled thereon. 105 are superposed, guided to the dryer 46 by the conveyor 45 via the press part 44, and dried and integrated by the dryer 46. By this method, the absorbent sheet 100 of the present invention can be manufactured at high speed and simply.
[0083]
The dispersion of the superabsorbent polymer and the hydrophilic fine fibers or hydrophilic fine powder will be described in more detail with reference to FIGS.
Here, FIG.2 and FIG.3 is schematic which shows the apparatus preferably used in order to manufacture the absorptive sheet of this invention.
[0084]
First, when the superabsorbent polymer 106 is sprayed after the hydrophilic fine fiber 14 or the hydrophilic fine powder 14 is sprayed, the fiber web formed by wet papermaking as shown in FIG. The hydrophilic fine fiber 14 or the hydrophilic fine powder 14 is sprayed on 108, and the superabsorbent polymer 106 is sprayed immediately thereafter. Subsequently, the fiber aggregate 105 previously made of paper is superimposed on the fiber web 108 on which the hydrophilic fine fibers 14 or the hydrophilic fine powder 14 and the superabsorbent polymer 106 are dispersed.
When the superabsorbent polymer 106 and the hydrophilic fine fiber 14 or the hydrophilic fine powder 14 are simultaneously sprayed, as shown in FIG. 3, the superabsorbent polymer 106 and the hydrophilic fine powder 14 are dispersed. Fine fibers 14 or hydrophilic fine powders 14 are uniformly mixed at a predetermined ratio in advance, and the mixture is dispersed on the fiber web 108 formed by wet papermaking. Next, the fiber aggregate 105 that has been made in advance is superposed on the fiber web 108 on which the mixture has been dispersed.
In FIG. 2, the order of the dispersion of the hydrophilic fine fibers 14 or the hydrophilic fine powder 14 and the dispersion of the superabsorbent polymer 106 may be reversed.
[0085]
As the wet paper machine, a normal paper machine can be used. Examples of such a paper machine include a long net paper machine and a round net paper machine. For steps other than those described above, steps in a normal papermaking method can be used as appropriate.
[0086]
As mentioned above, although the manufacturing method of the absorbent sheet of this invention was demonstrated based on the preferable aspect, it cannot be overemphasized that the manufacturing method of the absorbent sheet of this invention is not limited to this method. For example, the superabsorbent polymer 106 and the hydrophilic fine fiber 14 or the hydrophilic fine powder 14 may be dispersed and the fiber assembly 105 may be overlapped with the press part in FIGS. It may be performed at a position upstream or downstream of 44.
[0087]
Next, an absorbent article using the absorbent sheet of the present invention will be described.
[0088]
Absorbent articles using the absorbent sheet of the present invention,
In an absorbent article having a liquid-absorbable surface layer, a liquid-retaining absorbent layer, and a liquid-impermeable leak-proof layer,
The absorbent sheet is included on the surface layer, the absorbent layer, or the leakproof layer on the absorbent layer side.
[0089]
Hereinafter, preferred embodiments of the absorbent article will be described with reference to the drawings.
[0090]
First, a preferred embodiment of the absorbent article of the present invention will be described with reference to FIGS.
Here, FIG. 4 is a schematic view showing a cross section in the width direction of the sanitary napkin as the first preferred embodiment of the absorbent article of the present invention. 5 to 9 are schematic views (corresponding to FIG. 4) showing a cross-section in the width direction of a sanitary napkin as another preferred embodiment of the absorbent article of the present invention.
[0091]
A sanitary napkin 300 as a first preferred embodiment of the absorbent article of the present invention shown in FIG. 4 includes a liquid-absorbable surface layer 1, a liquid-impermeable leak-proof layer 3, and the surface layer and the leak-proof material. It comprises a liquid-retaining absorbent layer 2 interposed between the layers.
[0092]
More specifically, the sanitary napkin 300 is formed substantially vertically long, and when the sanitary napkin is worn, the surface layer 1 is located on the side in contact with the skin, and the leak-proof layer 3 is an underwear. Located on the side that touches.
[0093]
As will be described later, the absorbent layer 2 includes the absorbent sheet 100, the fluff pulp 2a, the absorbent sheet 100, and an absorbent paper 2b that covers the fluff pulp 2a. The leak-proof layer 3 covers the side surface portion and the bottom surface portion of the absorption layer 2. The surface layer 1 covers all the surfaces of the combination of the absorption layer 2 and the leak-proof layer 3.
[0094]
The surface layer 1 is not particularly limited as long as it can allow liquid to permeate the absorbing layer 2, but is preferably one having a feeling close to underwear. Examples of such surface layers include, for example, thermoplastic resin woven fabrics, nonwoven fabrics, and porous films. In particular, an apertured film made of polyolefin such as low density polyethylene can be preferably used.
[0095]
The leak-proof layer 3 is not particularly limited as long as it is liquid-impermeable, but is preferably moisture-permeable and has a feel close to underwear. The liquid-impermeable leak-proof layer having moisture permeability is formed by, for example, melting and extruding a thermoplastic resin added with an inorganic compound or an organic compound filler from a T die or a circular die, and then forming such a film. The film can be obtained by uniaxial or biaxial stretching.
[0096]
On the side of the sanitary napkin 300 in contact with the undergarment, two adhesive portions 4 and 4 are formed in a stripe shape in the longitudinal direction, and the adhesive portions 4 and 4 are separated by a release paper 5 before use. Protected. Moreover, in FIG. 4, the code | symbol 6 is a junction part for joining between said each members. In addition, about the point which is not specifically explained in detail, it is comprised similarly to the conventional sanitary napkin.
[0097]
  Next, characteristic parts of the absorbent article according to the first embodiment will be described.
  The sanitary napkin 300 as the absorbent article of the first embodiment includes the liquid-retaining absorbent layer 2, and the absorbent layer includes at least a superabsorbent polymer, bulky cellulose fibers, and hydrophilic fine particles. The absorbent sheet 100 includes fibers or hydrophilic fine powder. The absorbent sheet 100 is composed of a fiber assembly and a fiber web, and the fiber assembly and the fiber web are integrated.
  The fiber assembly has an absorption surface and does not contain the superabsorbent polymer on the absorption surface side, andAbove average fiber length 1-20mmMainly bulky cellulose fiber,
  The fiber web isAbove average fiber length 1-20mmMainly bulky cellulose fiber,
  The superabsorbent polymer is contained in the absorbent sheet and adhered to the fibers constituting the absorbent sheet.
  The hydrophilic fine fiber orthe aboveHydrophilic fine powderThe average fiber length or average powder particle size is 0.02 to 0.5 mm, And is mainly contained in the region where the superabsorbent polymer exists.
[0098]
By using the absorptive sheet, it is possible to obtain an absorptive article that is free from dropping of the superabsorbent polymer and gel blocking. In addition, since the absorbent sheet has functions of absorbing / transmitting and diffusing liquid and retaining liquid in a single structure, the absorbent sheet has the above functions as in the case of conventional liquid absorbent articles. Since it is not necessary to combine the members, a very thin liquid absorbent article can be obtained.
[0099]
According to the first preferred embodiment of the absorbent article of the present invention shown in FIG. 4, the liquid is absorbed by the sanitary napkin 300 through the surface layer 1. Thereafter, the fluff pulp 2a penetrates and is absorbed and held by the superabsorbent polymer dispersed in the absorbent sheet 100. In this case, it is preferable to arrange the absorbent sheet 100 so that the fiber assembly having the absorbent surface is located on the surface layer 1 side. By disposing the absorbent sheet in this manner, a preferable effect is obtained that the liquid absorbed by the fluff pulp 2a is more smoothly guided to the absorbent sheet 100.
[0100]
As described in detail in the description of the absorbent sheet 100, since the superabsorbent polymer is securely fixed to the absorbent sheet 100 without impairing the original absorbent characteristics of the superabsorbent polymer, The sanitary napkin 300 including the absorbent sheet 100 has a large liquid holding capacity. Moreover, since the sanitary napkin 300 shown in FIG. 4 includes the fluff pulp 2a in addition to the absorbent sheet 100, the liquid holding capacity is further increased. Therefore, the absorbent article of this embodiment is suitable as a sanitary napkin for night use worn for a long time.
[0101]
Next, 2nd-6th preferable embodiment of the absorbent article of this invention is shown in FIGS. In the second to sixth embodiments, the same points as those of the first embodiment are not specifically described in detail, but the description detailed in the first embodiment is appropriately applied. 5 to 9, the same members as those in FIG. 4 are denoted by the same reference numerals.
[0102]
In the sanitary napkin 100 as the second preferred embodiment of the absorbent article of the present invention shown in FIG. 5, the absorbent layer consists only of the absorbent sheet 100, and the side part of the absorbent sheet 100 and The bottom portion is covered with the leak-proof layer 3. The surface layer 1 covers all the surfaces of the combination of the absorbent sheet 100 and the leak-proof layer 3. In the present embodiment, similarly to the first embodiment, the absorbent sheet 100 is preferably arranged so that the fiber assembly having the absorbent surface is located on the surface layer 1 side. .
[0103]
Such a sanitary napkin 300 has a small number of members constituting the sanitary napkin 300, and since each member is thin, it can be an extremely thin sanitary napkin. Furthermore, since the superabsorbent polymer is securely fixed to the absorbent sheet 100 without impairing the inherent absorption characteristics of the superabsorbent polymer, the liquid holding capacity is large despite being thin. As a result, a sanitary napkin having a comfortable wearing feeling and a large liquid holding capacity can be obtained.
[0104]
In the sanitary napkin 300 as the third preferred embodiment of the absorbent article of the present invention shown in FIG. 6, the absorbent layer consists only of the absorbent sheet 100, and the absorbent sheet 100 is C-shaped. It is bent into a shape. The absorbent sheet 100 is covered with the leak-proof layer 3 on the side surface and the bottom surface. Furthermore, the surface layer 1 covers all the surfaces of the combination of the absorbent sheet 100 and the leak-proof layer 3. In the present embodiment, it is preferable that the absorbent sheet 100 be bent and disposed so that the fiber assembly having the absorbent surface is located on the surface layer 1 side.
[0105]
Such a sanitary napkin 300 is thicker than the sanitary napkin shown in FIG. 5 because the absorbent sheet 100 is bent in a C shape, but it still uses fluff pulp for the absorbent layer 2. The sanitary napkin shown in FIG. Moreover, since the absorbent sheet 100 is bent in a C shape, the liquid holding capacity is large. As a result, a sanitary napkin having a comfortable wearing feeling and a large liquid holding capacity can be obtained.
[0106]
In the sanitary napkin 300 as the fourth preferred embodiment of the absorbent article of the present invention shown in FIG. 7, the absorbent layer is formed by stacking a plurality of the absorbent sheets 100, 100,. 3 layers). And the said absorptive sheet | seat 100,100, ... which was piled up is covered with the said leak-proof layer 3 in the side part and bottom face part. Further, the surface layer 1 covers all the surfaces of the combination of the absorbent sheets 100, 100,. In the present embodiment, similarly to the first embodiment, the absorbent sheet 100 is preferably arranged so that the fiber assembly having the absorbent surface is located on the surface layer 1 side. .
[0107]
The sanitary napkin 300 is thicker than the sanitary napkin shown in FIG. 5 by the amount of the plurality of absorbent sheets 100 stacked, but it is still shown in FIG. 4 using fluff pulp for the absorbent layer 2. It can be made thinner than sanitary napkins. Moreover, since a plurality of the absorbent sheets 100 are stacked, the liquid holding capacity is large. As a result, a sanitary napkin having a comfortable wearing feeling and a large liquid holding capacity can be obtained.
[0108]
In the sanitary napkin 300 as the fifth preferred embodiment of the absorbent article of the present invention shown in FIG. 8, the absorbent sheet 100 functions as a liquid-absorbable surface layer and a liquid-retaining absorbent layer. (In other words, the absorbent article includes a liquid-retaining absorbent layer and a liquid-impermeable leak-proof layer). That is, the sanitary napkin 300 of the present embodiment includes an absorbent sheet 100 in which a liquid-absorbable surface layer and a liquid-retaining absorbent layer are integrated, and the side surface portion of the absorbent sheet 100 and The bottom part is covered with the leak-proof layer 3. In the present embodiment, the absorbent sheet 100 is particularly preferably disposed so that the fiber assembly having the absorbent surface is located on the side in contact with the skin.
[0109]
Such a sanitary napkin 300 has a reduced number of components and can be made thinner. As a result, it is possible to obtain a sanitary napkin that has a comfortable wearing feeling and can be manufactured by a simple process and at a low cost.
[0110]
In the sanitary napkin 300 as the sixth preferred embodiment of the absorbent article of the present invention shown in FIG. 9, the absorbent sheet comprises a surface layer capable of absorbing liquid, a liquid-retaining absorbent layer, and liquid impervious. The three functions of the leak-proof layer are also used. That is, the sanitary napkin 300 of this embodiment is formed by integrating a liquid-absorbable surface layer, a liquid-retaining absorbent layer, and a liquid-impermeable leak-proof layer. More specifically, the absorbent sheet 100 and a liquid-impermeable sheet 3 ′ bonded and integrated on a surface opposite to the liquid-absorbing surface of the absorbent sheet 100 are provided. In the present embodiment, the absorbent sheet 100 is disposed so that the fiber assembly having the absorbent surface is located on the side that absorbs the liquid, and the liquid impervious surface is opposite to the absorbent surface. It is particularly preferable to bond the sheet 3 '.
[0111]
Such a sanitary napkin 300 has a reduced number of components and can be made even thinner. As a result, it is possible to obtain a sanitary napkin that has a more comfortable wearing feeling and can be manufactured by a simpler process and at a lower cost. In addition to the sanitary napkin as shown in FIG. 9, the absorbent article of the present embodiment is also suitable as an absorbent article with a small amount of absorbing liquid such as a breast milk pad or a hygiene pad.
[0112]
【Example】
Next, the present invention will be described more specifically with reference to examples.
First, the production of bulky cellulose fibers, hydrophilic fine fibers, and hydrophilic fine powders used in Examples and Comparative Examples will be described. In the following description, “parts” and “%” represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.
[0113]
[Production Example 1]
Production of bulky cellulose fibers
5% of mercerized pulp (“POROSANIER-J” (trade name) manufactured by ITT RAYONIER INC.) Having a fiber roughness of 0.36 mg / m and a roundness of fiber cross section of 0.80 is 5%. Dimethylol dihydroxyethylene urea (crosslinking agent, "Sumitex Resin NS-19" (trade name) manufactured by Sumitomo Chemical Co., Ltd.) and 3% metal salt catalyst [Sumitex Accelerator X manufactured by Sumitomo Chemical Co., Ltd. -110 "(trade name)] was dispersed in 1000 g of an aqueous solution, and the mercerized pulp was impregnated with the crosslinking agent.
Next, the aqueous solution of the crosslinking agent is released from the mercerized pulp until the amount of the aqueous solution of the crosslinking agent with respect to the mercerized pulp reaches 200%, and then heated in an electric dryer at 135 ° C. for 10 minutes to form the mercerized product. The cellulose in the pulp was crosslinked to obtain mercerized crosslinked pulp. This is designated as cellulose fiber (A).
[0114]
[Production Example 2]
Production of bulky cellulose fibers
A crosslinked pulp (“High Bulk Additive HBA-S” (trade name) manufactured by Weyerhaeuser Paper) having a fiber roughness of 0.32 mg / m and a fiber cross-section roundness of 0.30 was prepared. This is designated as cellulose fiber (B).
[0115]
[Production Example 3]
Production of bulky cellulose fibers
Mercerized pulp (“POROSANIER-J” (trade name) manufactured by ITT RAYONIER INC.) Having a fiber roughness of 0.36 mg / m and a roundness of fiber cross section of 0.80 was prepared. This is designated as cellulose fiber (C). In addition, the cellulose fiber (C) is not crosslinked.
[0116]
[Production Example 4]
Production of bulky cellulose fibers
Softwood kraft pulp (“HARMAC-R” (trade name) manufactured by MacMillan Bloedel Ltd.) having a fiber roughness of 0.24 mg / m and a fiber cross-section roundness of 0.34 was prepared. This is designated as cellulose fiber (D). In addition, the cellulose fiber (D) is not crosslinked.
[0117]
[Production Example 5]
Production of bulky cellulose fibers
A softwood kraft pulp (“INDORAYON” (trade name) manufactured by PT Inti Indorayon Utama) having a fiber roughness of 0.35 mg / m and a roundness of fiber cross section of 0.28 was prepared. This is designated as cellulose fiber (E). In addition, the cellulose fiber (E) is not crosslinked.
[0118]
[Production Example 6]
Production of bulky cellulose fibers
Other than using hardwood kraft pulp (BAHIA SUL CELULOSE SA (trade name) manufactured by BAHIA SUL Co.) having a fiber roughness of 0.13 mg / m and a roundness of fiber cross section of 0.35 Produced a crosslinked pulp by the same method as in Production Example 1. This is designated as cellulose fiber (F).
[0119]
In addition, the fiber roughness of the cellulose fibers (A) to (F) in Production Examples 1 to 6 and the roundness of the fiber cross section were measured by the following methods.
[0120]
<Measurement of fiber roughness>
It was measured using a fiber roughness meter FS-200 (manufactured by KAJAANI ELECTRONICS LTD.). First, in order to determine the true weight of the cellulose fiber, the cellulose fiber is dried in a vacuum dryer at 100 ° C. for 1 hour to remove moisture present in the cellulose fiber.
Quickly weigh about 1 g of cellulose fiber at ± 0.1 mg accuracy. Next, in order not to damage the cellulose fiber, the cellulose fiber is completely disaggregated in 150 ml of water with a mixer attached to the fiber roughness meter, and this is diluted with water to 5000 ml. Was accurately measured, and this was used as a fiber roughness measurement solution, and the fiber roughness was determined according to the operation procedure of the fiber roughness meter.
[0121]
<Measurement of roundness of fiber cross section>
To measure the roundness of the cross section of the cellulose fiber, first, slice the cellulose fiber perpendicularly to the cross-sectional direction so that the area of the cross section of the cellulose fiber does not change, take a cross-sectional photograph with an electron microscope, and analyze the cross-sectional photograph Analysis was performed with an apparatus [“Avio EXCEL” (trade name) manufactured by Nippon Avionics Co., Ltd.], and the roundness of the cross section of the cellulose fiber was determined using the following formula. In addition, this roundness measured 100 points | pieces of arbitrary cellulose fiber cross sections, and made it the average value.
[0122]
[Expression 1]

[0123]
[Production Example 7]
Production of hydrophilic fine fibers
Cellulose fibers having an average fiber length of 0.12 mm, a fiber roughness of 0.09 mg / m, and a roundness of 0.31 of the fiber cross section are obtained by acid hydrolysis of the selected pulp, washing with water and drying, and then pulverizing by mechanical grinding. Hydrophilic fine fibers were obtained by crosslinking in the same manner as in Production Example 1 except that “KC Flock W-100” (trade name) manufactured by Sanyo Kokusaku Pulp Co., Ltd. was used. This is designated as hydrophilic fine fiber (G).
[0124]
[Production Example 8]
Production of hydrophilic fine fibers
Cellulose fibers with an average fiber length of 0.12 mm, a fiber roughness of 0.09 mg / m, and a fiber cross-section of roundness of 0.32 were obtained by acid hydrolysis of the selected pulp, washing with water, drying and then mechanically pulverizing. ["KC Flock W-100" (trade name) manufactured by Sanyo Kokusaku Pulp Co., Ltd.] was prepared. This is designated as hydrophilic fine fiber (H). The hydrophilic fine fibers (H) are not cross-linked.
[0125]
[Example 1]
Absorbent sheet manufacturing
Disperse and mix in 95 parts of cellulose fiber (A) and 5 parts of polyvinyl alcohol fiber [Fibrybond (trade name) manufactured by Sansho Co., Ltd., hereinafter referred to as PVA fiber] having a thickness of 1 denier and a length of 3 mm. After the predetermined concentration, the dispersion mixture was dried at a forming part of a wet paper machine with a dry basis weight of 70 g / m.²A fiber web was formed so that The fiber web was then dewatered with a suction box until the moisture content was 150 parts based on 100 parts of the dry fiber web. Next, just before the press part, the hydrophilic fine fiber (G) is sprayed on the wet fiber web after dewatering. The basis weight is 20 g / m.²And spray a superabsorbent polymer [Nippon Shokubai Co., Ltd., Aquaric CAW-4 (trade name)] with a basis weight of 50 g / m.²Sprayed almost uniformly.
Absorption which made paper in advance which has the same composition composition as the above-mentioned fiber web as a fiber aggregate on the side which sprinkled each of the above-mentioned hydrophilic fine fiber (G) and superabsorbent polymer among the above-mentioned fiber webs Paper (30 g / m²), And a laminated body of the fiber web and absorbent paper is introduced into a dryer, dried at 130 ° C., and integrated, whereby the hydrophilic fine fibers (G) and the superabsorbent polymer are contained inside. A fixed absorbent sheet was obtained. Let this absorptive sheet be an absorptive sheet (A).
[0126]
[Example 2]
Absorbent sheet manufacturing
95 parts of cellulose fiber (B) and 5 parts of low-melting polyester fiber having a thickness of 1.1 denier and a length of 5 mm [TM-07N (trade name) manufactured by Teijin Ltd., hereinafter referred to as PET fiber] are submerged in water. After dispersing and mixing to a predetermined concentration, the dispersion mixture is dried at a forming part of a wet paper machine with a dry basis weight of 70 g / m.²A fiber web was formed so that Then, the fiber web is dehydrated by a suction box until the water content becomes 100 parts based on 100 parts of the dry fiber web, and hydrophilic fine fibers (on the wet fiber web after passing through the press part ( G) spraying basis weight 20g / m²And spray a superabsorbent polymer [Nippon Shokubai Co., Ltd., Aquaric CAW-4 (trade name)] with a basis weight of 50 g / m.²Sprayed almost uniformly.
Absorption which made paper in advance which has the same composition composition as the above-mentioned fiber web as a fiber aggregate on the side which sprinkled each of the above-mentioned hydrophilic fine fiber (G) and superabsorbent polymer among the above-mentioned fiber webs Paper (30 g / m²), And a laminated body of the fiber web and absorbent paper is introduced into a dryer, dried at 130 ° C. and integrated to fix the hydrophilic fine fibers and the superabsorbent polymer inside. A single absorbent sheet was obtained. Let this absorptive sheet be an absorptive sheet (B).
[0127]
Example 3
Absorbent sheet manufacturing
Using the formulation shown in Table 1, a uniform mixture of hydrophilic fine fibers and a superabsorbent polymer was distributed almost uniformly to each with a basis weight of 50 g / m.²An absorptive sheet was obtained by the same operation as in Example 2 except that it was sprayed. Let this absorptive sheet be an absorptive sheet (C).
[0128]
Example 4
Made of absorbent sheetConstruction
Using the formulation shown in Table 1, a uniform mixture of hydrophilic fine fibers and a superabsorbent polymer was distributed almost uniformly to each with a basis weight of 50 g / m.²An absorptive sheet was obtained by the same operation as in Example 1 except that it was sprayed. Let this absorptive sheet be an absorptive sheet (D).
[0129]
[Examples 5 and 6]
Made of absorbent sheetConstruction
Using the formulation shown in Table 1, a uniform mixture of hydrophilic fine fibers and a superabsorbent polymer was distributed almost uniformly to each with a basis weight of 50 g / m.²An absorptive sheet was obtained by the same operation as in Example 1 except that it was sprayed. Let this absorptive sheet be an absorptive sheet (E) and (F), respectively.
[0130]
[Comparative Example 1]
Absorbent sheet manufacturing
95 parts of cellulose fiber (D) and 5 parts of PVA fiber having a thickness of 1 denier and a length of 3 mm are dispersed and mixed in water, paper-made using a paper machine, and then dried to have a basis weight of 70 g / m.²The absorbent paper was manufactured in advance. An absorbent sheet was produced by the following method using the absorbent paper.
That is, water is sprayed on the absorbent paper to 200 parts based on 100 parts of the absorbent paper (dry). Next, a superabsorbent polymer (Nippon Shokubai Co., Ltd., Aquaric CAW-4 (trade name)) is sprayed on the wet absorbent paper for application of 50 g / m.²Sprayed almost uniformly.
The basis weight of 30 g / m having the same composition as that of the absorbent paper on the surface of the absorbent paper on which the superabsorbent polymer is dispersed.²After superposing the two absorbent papers, the two superposed sheets of absorbent paper were pressure-bonded and integrated, and then dried with a drier to obtain a total basis weight of 150 g / m.²An absorbent sheet was obtained. In the absorbent sheet, the absorbent paper in which the superabsorbent polymer is dispersed is in a state in which the constituent fibers are strongly restrained even after the water is dispersed, and is not in the state of the fiber web referred to in the present invention. The absorbent sheet is a sheet in which a superabsorbent polymer is sandwiched between the absorbent papers. This absorbent sheet is referred to as an absorbent sheet (G).
[0131]
[Comparative Example 2]
Absorbent sheet manufacturing
95 parts of cellulose fibers (E) and 5 parts of low-melting point PET fibers having a thickness of 1.1 denier and a length of 5 mm are dispersed and mixed in water, paper-made using a paper machine, dried, and a basis weight of 70 g / m²The absorbent paper was manufactured in advance. An absorbent sheet was produced by the following method using the absorbent paper.
That is, on the absorbent paper, an adhesive [Movinyl 710 (trade name) from Hoechst Chemical Co., Ltd.] is basis weight 20 g / m.²Next, a superabsorbent polymer [manufactured by Nippon Shokubai Co., Ltd., Aquaric CAW-4 (trade name)] is applied on the above absorbent paper, and the basis weight is 50 g / m.²Sprayed almost uniformly.
The basis weight of 30 g / m having the same composition as that of the absorbent paper on the surface of the absorbent paper on which the superabsorbent polymer is dispersed.²After superposing the two absorbent papers, the two superposed sheets of absorbent paper were pressure-bonded and integrated, and then dried with a drier to obtain a total basis weight of 150 g / m.²An absorbent sheet was obtained. In this absorbent sheet, the absorbent paper sprayed with the superabsorbent polymer is not a wet fiber web, but is a pulp fiber that is strongly constrained to each other, and is highly absorbent between two absorbent papers. The functional polymer is sandwiched in layers. Let this absorptive sheet be an absorptive sheet (H).
[0132]
[Comparative Example 3]
Absorbent sheet manufacturing
95 parts of cellulose fiber (F) and 5 parts of PVA fiber having a thickness of 1 denier and a length of 3 mm are dispersed and mixed in water, paper-made using a paper machine, and then dried to have a basis weight of 70 g / m.²An absorbent paper was prepared beforehand. An absorbent sheet was produced by the following method using the absorbent paper.
That is, water is sprayed on the absorbent paper to 10 parts based on 100 parts of the absorbent paper (dry). Next, a superabsorbent polymer [Nippon Shokubai Co., Ltd., Aquaric CAW-4 (trade name)] is sprayed on the wet absorbent paper.²Sprayed almost uniformly.
The basis weight of 30 g / m having the same composition as that of the absorbent paper on the surface of the absorbent paper on which the superabsorbent polymer is dispersed.²The two sheets of absorbent paper are superposed, and the superposed body of the two absorbent papers is embossed and bonded through a grid embossing roll partitioned in 5 and 5 mm sections in the vertical and horizontal directions, then dried with a dryer, and the total basis weight is 150 g. / M²An absorbent sheet was obtained. In the absorbent sheet, the absorbent paper in which the superabsorbent polymer is dispersed is in a state in which the constituent fibers are strongly restrained even after the water is dispersed, and is not in the state of the fiber web referred to in the present invention. The absorbent sheet is a sheet in which a superabsorbent polymer is sandwiched between the absorbent papers. This absorbent sheet is referred to as an absorbent sheet (I).
[0133]
[Comparative Example 4]
Absorbent sheet manufacturing
45g / m basis weight formed by air raid method²45 g / m of superabsorbent polymer between pulp sheets²Then, an absorbent sheet having a pulp fixed with a chemical binder was produced.
Let this absorptive sheet be an absorptive sheet (J).
[0134]
[Comparative Example 5]
Absorbent sheet manufacturing
A dry absorbent sheet containing synthetic pulp and superabsorbent polymer was produced.
That is, a pulp sheet composed of 25 parts of polyethylene synthetic pulp and 75 parts of chemical pulp was defibrated with a hammer mill, and the basis weight was 100 g / m.²When forming a dry absorbent sheet, 50 g / m of superabsorbent polymer [manufactured by Nippon Shokubai Co., Ltd., Aquaric CAW-4 (trade name)]²The polyethylene synthetic pulp was then fused and integrated by hot air treatment. This dry absorbent sheet has a superabsorbent polymer on its surface. This absorbent sheet is referred to as an absorbent sheet (K).
[0135]
Tables 1 and 2 show the composition and manufacturing method of the absorbent sheets (A) to (F) in Examples 1 to 4 and the absorbent sheets (G) to (K) in Comparative Examples 1 to 5, respectively.
[0136]
[Table 1]

[0137]
[Table 2]

[0138]
In order to evaluate the high-absorbency polymer immobilization ability and the absorption performance of the absorbent sheets (A) to (F) in Examples 1 to 6 and the absorbent sheets (G) to (K) in Comparative Examples 1 to 5 The thickness, the dropout test of the superabsorbent polymer, the saturated absorption amount, the absorption rate, and the liquid return amount were measured by the methods described below. Each result is shown in Table 3.
[0139]
<Thickness>
2.5 g / cm on the upper surface of the absorbent sheet cut to an appropriate size²The load was applied and the thickness was measured. The average value of a total of 10 points was taken as the thickness.
[0140]
<Dropping test of superabsorbent polymer>
After measuring the weight of the absorbent sheet cut out to 70 × 200 mm, it is put in a plastic bag with a chuck of 280 mm in length × 200 mm in width, and in this state, vibration is given while shaking it 50 times. After the test is completed, the weight change of the absorbent sheet is measured, and colored water (0.3 g / 100 ml of water) stained with blue No. 1 is used so that the superabsorbent polymer dropped into the plastic bag can be observed with the naked eye. In addition to the plastic bag, the superabsorbent polymer is swelled, and the degree of dropping is visually determined.
○: Almost no loss of superabsorbent polymer is observed.
Δ: Some loss of superabsorbent polymer is observed.
X: Dropping of the superabsorbent polymer is considerably observed.
The measurement was conducted 10 times, and the average value was used as the amount of dropout.
[0141]
<Saturated absorption>
A 5 cm square absorbent sheet was put in a bag made of non-woven fabric, and the bag was immersed in ion-exchanged water for 10 minutes. After removing the bag from the ion exchange water, suspend it in the air for 1 hour, drop the adhering water, measure the weight, and determine the increase in weight per gram of the absorbent sheet as the saturated absorption amount (g / g ).
[0142]
<Absorption rate>
As shown in FIG. 12, a 10 cm square transparent acrylic plate 20 having a 1 cm diameter hole and a weight 22 are placed in the center of a 15 cm square absorbent sheet 100, and 5 g / cm is placed on the absorbent sheet 100.²Under the condition of applying the load, 20 ml of physiological saline was injected through the hole, and the time required for absorption of physiological saline was defined as the absorption rate. The absorption rate was measured twice, but the second injection (reabsorption rate) was performed 1 minute after the first measurement.
[0143]
<Measurement of liquid return amount>
As shown in FIG. 15, 10 sheets of 15 cm square filter paper 24 (Toyo Filter Paper Type 2) are stacked on the absorbent sheet after 10 minutes have elapsed after measuring the absorption speed, and further, a 15 cm square acrylic plate 26 is weighted thereon. 22, 50 g / cm²Then, the filter paper 24 was taken out, and the weight of the physiological saline absorbed by the filter paper 24 was taken as the liquid return amount.
[0144]
[Table 3]

[0145]
Example 7
Production of absorbent articles
A sanitary napkin having the configuration shown in FIG. 6 was produced.
That is, as the absorbent fiber sheet 10, an absorbent sheet (A) having a length of 175 mm and a width of 145 mm was folded and compressed into a C shape so that both side edges faced approximately at the center of the absorbent body to a width of 73 mm. This absorption sheet (A) was used as an absorber.
As the leak-proof layer 3, polyla waterproof paper (length 205 mm, width 95 mm) was used, and the side and bottom portions of the absorbent sheet were covered with the polyla waterproof paper. A hot melt adhesive used as a fixing agent 6 in which all surfaces of the combination of the absorbent sheet 10 and the polylaminated waterproof paper are covered with a liquid-absorbable surface layer 1 (length 205 mm, width 172 mm) described later. These members were fixed with an agent. Furthermore, a grammage of 30 g / m on the opposite side of the surface layer 1²Two hot-melt pressure-sensitive adhesives having a width of 20 mm and a length of 115 mm were applied as the adhesive portions 4. In this way, a sanitary napkin having the configuration shown in FIG. 6 was obtained.
In addition, as the surface layer 1, a polyethylene perforated film was used. This surface layer 1 has a basis weight of 30 g / m.²The polyethylene film is perforated, and one perforation diameter is 0.5 mm and the perforation area ratio is 20%.
[0146]
[Examples 8 to 10]
Production of absorbent articles
A sanitary napkin having the structure shown in FIG. 6 was used in the same manner as in Example 7 except that the absorbent sheets (B) to (D) were used instead of the absorbent sheet (A) used in Example 7. Obtained.
[0147]
Production of absorbent articles
[Comparative Examples 6 to 10]
A sanitary napkin having the structure shown in FIG. 6 was used in the same manner as in Example 7 except that the absorbent sheets (G) to (K) were used instead of the absorbent sheet (A) used in Example 7. Obtained.
[0148]
About sanitary napkins in Examples 7 to 10 and Comparative Examples 6 to 10, in order to evaluate polymer immobilization ability and absorption performance, polymer dropping test, product thickness, absorption time, dynamic liquid return amount, A leak test was performed on each sanitary napkin. Each result is shown in Table 4.
[0149]
<Dropping test of superabsorbent polymer>
After measuring the weights of the sanitary napkins of Examples 7 to 10 and Comparative Examples 6 to 10, the sanitary napkins were placed in a plastic bag with a chuck having a length of 280 mm and a width of 200 mm, and in this state, vibration was performed while shaking by hand 50 times. Add. After the test is completed, the weight change of the sanitary napkin is measured, and colored water (0.3 g / 100 ml of water) dyed with Blue No. 1 is used so that the superabsorbent polymer dropped into the plastic bag can be observed with the naked eye. In addition to the plastic bag, the superabsorbent polymer is swelled, and the degree of dropping is visually determined.
○: Almost no loss of superabsorbent polymer is observed.
Δ: Some loss of superabsorbent polymer is observed.
X: Dropping of the superabsorbent polymer is considerably observed.
The measurement is performed 10 times, and the average value is taken as the amount of dropout.
[0150]
<Measurement of product thickness>
As shown in FIG. 11, 10 sanitary napkins were overlapped, an acrylic plate weighing 500 g was placed from above, and the thickness of 10 sheets was measured to obtain the product thickness per sheet.
[0151]
<Measurement of absorption time (5 g), reabsorption time (10 g), dynamic liquid return amount>
The absorption time measuring device shown in FIG. 12 was used. That is, instead of the absorbent sheet 100 shown in FIG. 13, the sanitary napkin 300 obtained in Examples 7 to 10 and Comparative Examples 6 to 10 was placed horizontally, and the acrylic plate 20 with an inlet having a diameter of 1 cm was attached. Place weight 22 on top of this and put it on sanitary napkin 300 at 5 g / cm²It seemed to be loaded.
Next, 5 g of defibrinated horse blood (manufactured by Nippon Biotest Laboratories) is injected from the injection port, and the absorption time (seconds) until the defibrinated horse blood is completely absorbed is determined. After the defibrinated horse blood was completely absorbed, it was left as it was for 20 minutes, 5 g of defibrinated horse blood was injected again, the reabsorption time (10 g) was obtained, and left for 20 minutes in the same manner.
Then basis weight 30g / m²14 is placed on the upper surface (skin contact surface side) of the sanitary napkin and 10 sheets of absorbent paper made of softwood kraft pulp having a length of 195 mm and a width of 75 mm are shown in FIG. Thus, after putting on the shorts to which the sanitary napkin 80 was attached, it was walked for 1 minute at a walking speed of 100 seconds / minute (50 m / minute).
After the end of walking, the sanitary napkin 80 and 10 sheets of absorbent paper were taken out, and the weight of defibrinated horse blood absorbed by the absorbent paper was determined as the liquid return amount (g). Each of the five points was measured, the average value of each was obtained, and the absorption time, reabsorption time, and dynamic liquid return amount were obtained.
[0152]
<Leakage test (number of leaks)>
As shown in FIG. 14, the sanitary napkin 80 obtained in Examples 7 to 10 and Comparative Examples 6 to 10 was attached to a movable female waist model 90, and after wearing shorts, 100 steps / min (50 m / min) Minutes) at a walking speed of 10 minutes).
Next, while walking, 5 g of defibrinated horse blood was injected into the sanitary napkin 80 through the tube 91, and then walked at the same speed for 20 minutes (5 g absorption), and then further 5 g of defibrinated horse blood was injected. At the time of walking for 20 minutes at the same speed (10 g absorption), out of 10 samples at each time point, the number of leaks was counted.
[0153]
[Table 4]

[0154]
As is apparent from the results shown in Tables 3 and 4, the absorbent article of the present invention using a specific absorbent sheet is obtained by conventional absorbent sheets (water spraying, embossing integration, or integration with an adhesive). Compared to an absorbent article having an absorbent sheet), the superabsorbent polymer has excellent fixability, and even when an extremely thin absorbent sheet is used, it has excellent absorption characteristics such as absorption rate and liquid return amount. I understand.
In addition, the absorbent article of the present invention has a very high performance even though it has a very simple structure, and has a fast liquid absorption time, a small amount of liquid return, and a small number of leaks. . This is because the absorbent sheet used in the absorbent article of the present invention has a liquid absorption diffusion gradient in its single structure, so that the liquid can be absorbed quickly and the inside of the absorbent sheet smoothly. This is because the liquid permeates and the liquid diffuses sufficiently.
[0155]
【The invention's effect】
As described in detail above, according to the present invention, there is provided an absorbent sheet in which the superabsorbent polymer is securely fixed in the sheet, the superabsorbent polymer is hardly dropped, and the superabsorbent polymer is hardly gel-blocked. can get. The absorbent sheet has three functions of permeation / diffusion / retention of liquid in a single structure, and is excellent in both absorption speed and absorption power.
[0156]
Moreover, according to the preferable method for manufacturing the absorbent sheet of the present invention, the manufacturing process is greatly accelerated as compared with the conventional method for manufacturing an absorbent sheet. Moreover, a complicated processing process for fixing the superabsorbent polymer is not required, and the manufacturing process is greatly simplified.
[0157]
In addition, according to the above production method, not only the superabsorbent polymer can be sprayed over the entire absorbent sheet, but can also be partially sprayed in the longitudinal direction or intermittently sprayed in the longitudinal direction. Accordingly, the range in which the superabsorbent polymer is dispersed can be set, and the absorbent sheet can be produced more economically.
[0158]
Furthermore, according to the present invention, it is possible to provide an ultrathin absorbent article in which a large amount of superabsorbent polymer is fixed despite being extremely thin. In addition, the absorbent article has a high liquid absorption rate, a small liquid return amount, and a small number of leaks. In particular, when the absorbent layer is composed of only the above-described absorbent sheet, the absorbent article can be manufactured by cutting only one absorbent sheet, and the absorbent article can be manufactured at a high speed by an extremely simple manufacturing process. Can be produced. In addition, since the absorbent sheet has an integrated structure, the superabsorbent polymer absorbs even when the absorbent article equipped with the absorbent sheet is worn and exercises violently. Absorption performance does not deteriorate due to separation from the sheet.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a cross section of a preferred embodiment of an absorbent sheet of the present invention.
FIG. 2 is a schematic view showing an apparatus preferably used for producing the absorbent sheet of the present invention.
FIG. 3 is a schematic view showing an apparatus preferably used for producing the absorbent sheet of the present invention.
FIG. 4 is a schematic view showing a cross section of a sanitary napkin as a first embodiment of the absorbent article of the present invention.
FIG. 5 is a schematic view showing a cross section of a sanitary napkin as a second embodiment of the absorbent article of the present invention.
FIG. 6 is a schematic view showing a cross section of a sanitary napkin as a third embodiment of the absorbent article of the present invention.
FIG. 7 is a schematic view showing a cross section of a sanitary napkin as a fourth embodiment of the absorbent article of the present invention.
FIG. 8 is a schematic view showing a cross section of a sanitary napkin as a fifth embodiment of the absorbent article of the present invention.
FIG. 9 is a schematic view showing a cross section of a sanitary napkin as a sixth embodiment of the absorbent article of the present invention.
FIG. 10 is a schematic view showing a cross section of a conventional absorbent sheet.
FIG. 11 is a schematic diagram showing the measurement of the thickness of a sanitary napkin.
FIG. 12 is a schematic diagram showing measurement of absorption time.
FIG. 13 is a diagram showing a movable female waist model.
FIG. 14 is a schematic diagram showing a state in which a sanitary napkin is attached to the crotch portion of the movable female waist model.
FIG. 15 is a schematic diagram showing measurement of a liquid return amount.
[Explanation of symbols]
100 Absorbent sheet
102 Absorbing surface
105 Fiber assembly
106 Superabsorbent polymer
108 Fiber web
300 Absorbent articles

Claims (13)

An absorbent sheet comprising at least a superabsorbent polymer, bulky cellulose fibers, and hydrophilic fine fibers or hydrophilic fine powders,
The absorbent sheet is composed of a fiber assembly and a fiber web, and the fiber assembly and the fiber web are integrated.
The fiber assembly has an absorbent surface and does not contain the superabsorbent polymer on the absorbent surface side, and is mainly composed of the bulky cellulose fiber having an average fiber length of 1 to 20 mm ,
The fiber web is mainly composed of the bulky cellulose fiber having an average fiber length of 1 to 20 mm ,
The superabsorbent polymer is contained in the absorbent sheet and adhered to the fibers constituting the absorbent sheet.
The hydrophilic fine fibers or the hydrophilic fine powder has an average fiber length or an average powder particle size of 0.02 to 0.5 mm, is included in the main in the area in the presence of the superabsorbent polymer An absorbent sheet characterized by   The absorbent sheet according to claim 1, wherein the superabsorbent polymer and the hydrophilic fine fibers or hydrophilic fine powder are mainly contained in the fiber web. The basis weight of the fiber assembly is 10 to 200 g / m ² , the spreading basis weight of the superabsorbent polymer is 1 to 300 g / m ² , and the hydrophilic fine fiber or hydrophilic fine powder is used. spraying a basis weight of 1 to 300 g / m ^2, and the basis weight of the fiber web is 10 to 200 g / m ^2, according to claim 1 or 2 absorbent sheet according.   The absorptive sheet in any one of Claims 1-3 whose fiber roughness of the said bulky cellulose fiber is 0.3 mg / m or more.   The absorbent sheet in any one of Claims 1-4 whose roundness of the fiber cross section of the said bulky cellulose fiber is 0.5-1.   The absorbent sheet according to any one of claims 1 to 5, wherein the bulky cellulose fiber is a crosslinked cellulose fiber.   The hydrophilic fine fiber or the hydrophilic fine powder has a fiber roughness of less than 0.1 mg / m or a fiber roughness of less than 0.3 mg / m and a perfect circle of the fiber cross section. The absorptive sheet in any one of Claims 1-6 whose degree is 0-0.5. The absorbent sheet according to any one of claims 1 to 7, wherein an average fiber length of the hydrophilic fine fibers or an average powder particle diameter of the hydrophilic fine powders is 0.1 to 0.3 mm. .   The absorbent sheet according to any one of claims 1 to 8, wherein the hydrophilic fine fiber or the hydrophilic fine powder is subjected to a crosslinking treatment. It is a manufacturing method of the absorptive sheet according to claim 1,
With sparging superabsorbent polymer on wet fiber web comprising at least the bulky cellulose fibers, the hydrophilic fine fibers sprayed simultaneously with or before and after the high-absorbent polymer or the hydrophilic fine Sprinkle powder,
A method for producing an absorbent sheet, comprising the steps of superimposing the fiber assembly thereon and drying and integrating them.   The manufacturing method according to claim 10, wherein the fiber web is made by wet papermaking. The fiber web is formed in a forming part, the fiber web is dehydrated in a suction dewatering step, and then the superabsorbent polymer is sprayed on the fiber web, and at the same time or before and after the spraying of the superabsorbent polymer. the hydrophilic fine fibers or sprayed with the hydrophilic fine powder, overlay the fiber aggregate thereon, and comprising the step of integrating and dried them with a dryer, a manufacturing method of claim 10 wherein in . In an absorbent article having a liquid-absorbable surface layer, a liquid-retaining absorbent layer, and a liquid-impermeable leak-proof layer,
An absorbent sheet containing at least a superabsorbent polymer, bulky cellulose fibers, and hydrophilic fine fibers or hydrophilic fine powders on the surface layer, the absorbent layer, or the absorbent layer side of the leak-proof layer. Is included,
The absorbent sheet is composed of a fiber assembly and a fiber web, and the fiber assembly and the fiber web are integrated.
The fiber assembly has an absorbent surface and does not contain the superabsorbent polymer on the absorbent surface side, and is mainly composed of the bulky cellulose fiber having an average fiber length of 1 to 20 mm ,
The fiber web is mainly composed of the bulky cellulose fiber having an average fiber length of 1 to 20 mm ,
The superabsorbent polymer is contained in the absorbent sheet and adhered to the fibers constituting the absorbent sheet.
The hydrophilic fine fibers or the hydrophilic fine powder has an average fiber length or an average powder particle size of 0.02 to 0.5 mm, is included in the main in the area in the presence of the superabsorbent polymer An absorbent article characterized by having

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