JP2004512862A - Absorbent barrier structures with high convective airflow velocity and products made therefrom - Google Patents

Abstract

The present invention relates to absorbent articles having improved protection and comfort through the use of an absorbent barrier structure. This is achieved by the selection of individual components that meet specific requirements, the combination of which provides an absorbent article with the desired performance.

Description

式中、Ｈは試料の積み重ねを圧縮するために圧力が適用された後の全体的厚さであり、
ｄは試料の積み重ねの最初の厚さであり、
ｎは試料シートの層の数であり、
ｋは圧縮水準である。
【０１８４】
圧縮された試料の積み重ねは、予め定められた時間、６０℃、相対的湿度５０％に環境制御した部屋の中に配置される。一般的に、試験は各々を積み重ね５０％圧縮した５試料シート又は積層体で行われる。試験は試料シートのいずれかの数の層に又は異なる圧縮水準で適用されてもよい。
【０１８５】
試料の空気透過性は圧縮前及び２４時間の圧縮後に決定される。圧縮後の空気透過性は、待機時間後に測定され、それは試料を回復させる（試料は永久的変形を表さない可能性があること及び最初の圧縮前状態まで回復しないことを考慮して）のに充分な時間である。この試験では、空気透過性は空気の標準量が一定の圧力及び温度で試験試料を通過する時間を測定することにより決定される。
【０１８６】
試験は、温度及び湿度を２２±２℃及び相対的湿度３５％±１５％に制御した環境で行われる。試験試料は少なくとも２時間調湿される必要がある。
【０１８７】
「テキスチルールナッハクレッチマー（Ｔｅｘｔｉｌｕｈｒ ｎａｃｈ Ｋｒｅｔｓｃｈｍａｒ）」の名称でホップアンドシュナイダー（Ｈｏｐｐｅ ＆ Ｓｃｈｎｅｉｄｅｒ ＧｍｂＨ）（ドイツ、ヘイデルベルグ（Ｈｅｉｄｅｌｂｅｒｇ））により製造されるような試験装置は、本質的に垂直に配置されるベローであり、その上部末端部は固定された位置で取り付けられ、下部末端部はその上部の位置で開放可能に保持され、それは開放ハンドルにより緩められ、制御された状態でより低い位置まですべり、それにより空気をベローの上部末端部で空気が入る開口部を覆っている試験試料に引き込むことによりベロー内部の容積を増す。試験試料はしっかりと保持されて５ｃｍ^２又は１０ｃｍ^２の締着環により空気の入る開口部を覆い、異なる試料寸法及び／又は異なる透過性の範囲を可能にする。１０ｃｍ^２環を使用する場合、試料は少なくとも幅５５ｍｍであり、５ｃｍ^２の環では少なくとも幅３５ｍｍである必要がある。両方について試料は約１５０ｍｍの長さを有する必要がある。
【０１８８】
非常に高い透過性材料の場合、装置及び計算に適切な調整を行って開口部はさらに縮小可能である。
【０１８９】
装置は、ストップウオッチ（１／１００秒）を備え、開放ハンドルが操作してベローのすべりを開始する時と、ベローの低部がより低い末端位置に達する間の時間を自動的に測定する。
【０１９０】
材料の空気透過性ｋは上記のダルシー法則により計算され、そこでは異なるパラメーターが使用される（装置機構の違いのために）。特にここで使用される試験装置について、Ｖは１９００ｃｍ^３であり、Ａは４．１５５ｃｍ^２であり、ｐは１６０Ｐａである。
【０１９１】
試験は各試験試料（単一材料又は異なる材料の積層体から作成されるいずれかのシート）について一回行い、５試料について繰り返す必要がある。各試料材料又は積層体について、少なくとも３回の有用な試験の平均値を記録する。
【０１９２】
平均値は、材料の単位厚さを考慮して、ダルシー／ｍｍで記録する。
【０１９３】
Ｇ．吸収試験
この試験は、吸収性材料の高吸引毛管の吸収性を測定する。毛管収着は、流体が吸収性構造体にどのように吸収されるかを管理するいずれかの吸収剤の基本的特性である。高吸引毛管収着は、競争する材料から流体を仕切る物質の能力に特徴がある。
【０１９４】
多孔質ガラスフリットは流体のさえぎられない円柱を介して流体貯臓器に接続され、その流体水準はフリット多孔質構造体の水平の中央部と同じ高さに位置する。試料は必要な流体を吸収し、その安定した状態の重量を記録する。固定した高さの吸収実験は、このように水平方向における液体吸い上げ（ｇ／ｇ）についての情報を提供する。
【０１９５】
（実験準備）
本明細書で使用される試験液体は、約３３ダイン／ｃｍの表面張力を持つ０．２重量％トリトン（Ｔｒｉｔｏｎ）（登録商標）Ｘ−１００（シグマアルドリッヒ社（Ｓｉｇｍａ−Ａｌｄｒｉｃｈ Ｉｎｃ．）から入手可能）水溶液である。この試験方法は、水又は合成尿（約７５ダイン／ｃｍ及び約５５ダイン／ｃｍの表面張力を持つ）のような他の試験液体類を使用するのに適合している。
【０１９６】
多孔性ガラスフリット漏斗は試験液体で充填される。このフリット漏斗（ＶＷＲサイエンティフィックプロダクツ（ＶＷＲ Ｓｃｉｅｎｔｉｆｉｃ Ｐｒｏｄｕｃｔｓ）（オハイオ州クリーブランド（Ｃｌｅｖｅｌａｎｄ））から入手可能）は、３５０ｍｌの容積及び１０〜１５ミクロンの孔を持ち、その底部出口はガラスブロアーにより改良され、管材料の収容能力を持つ。１．４０ｍの長さのタイゴン（Ｔｙｇｏｎ）管（部品Ｎｏ．Ｒ３６０３、ＶＷＲサイエンティフィックプロダクツ（ＶＷＲ Ｓｃｉｅｎｔｉｆｉｃ Ｐｒｏｄｕｃｔｓ）から入手可能）を漏斗の底部に取り付け、試験液体で充填する。フリット漏斗はスタンドにクランプ留めされる。タイゴン（Ｔｙｇｏｎ）管末端部は、フリットディスクから数センチメートル上がった官末端部でフリット漏斗に取り付けられる。
【０１９７】
漏斗には試験液体１００ｍｌが充填され（上がった管末端部は液体がフリットから流れ出るのを防ぐ）塑性体のラップで覆われる。その後フリットは５〜１２時間保管され、フリット孔に閉じ込められたいずれの空気も逃げるのを可能にする。いずれの観察できる空気の泡もフリット又は管から除去される必要がある。タイゴン（Ｔｙｇｏｎ）管は、試験流体を充填したガラス流体貯臓器（直径２０〜２５ｃｍ）に配置される。フリットの中央及び貯臓器領域の流体水準は同じ高さに設定される。水準器を使用してフリット表面が水平であることを確実にする。
【０１９８】
実験と実験の間にフリット漏斗は塑性体のラップで覆われ、フリット孔からの試験液体の蒸発及び乾燥を防ぐが、実験中フリット漏斗は覆われない。
【０１９９】
フリットが数時間使用されない場合、次のように保管される必要がある。タイゴン（Ｔｙｇｏｎ）管は流体貯臓器から取り除かれ、フリットディスクから数センチメートル上に上がった管末端部でフリット漏斗に取り付けられる。漏斗は試験液体１００ｍｌで充填され（上がった管末端部は液体がフリットから流れ出るのを防ぐ）、プラスチックラップで覆われる。
【０２００】
（実験手順）
観察できる空気の泡がフリットの下又は管の中に閉じ込められていないことを確認する。アーチパンチを用いて直径５．４０ｃｍの試料を切断する。試料の重さを量る。フリット漏斗の下のクランプを分離する。試料をフリット表面の中央領域に平らに広げる。試料上に環状おもりを配置する。クランプを取り除き、試料に２．５分間吸収させる。環状おもりを取り除き、その後フリットから試料を取り除く。試料除去のためにフリット漏斗をさらに低くするか又は傾かせる必要がある場合、試料をフリットから取り外す前にフリット漏斗の下のフリット漏斗管のクランプを外す必要がある（取り外し中に追加の流体が試料により吸収されないことを確実にするために）。試料の重さを量る。次の試料で手順を繰り返す。各試料について２回繰り返し、各フリットについて得られた正味吸い上げ量及び平均正味吸い上げ量を記録する。どのフリットを使用したかを記録する（フリット＃又は他の識別番号）。二つの試験の結果が１０％より多く異なる場合（より高い値に基づき）、フリット及び試料の調整を調べ実験を繰り返す。試料により液体の吸収性（又は吸い上げ）を次のように計算する。
【０２０１】
正味吸い上げｇ／ｇ＝（試料湿潤重量ｇ−試料乾燥重量ｇ）／試料乾燥重量ｇ　　（実地例）
（実施例１）
この例では本発明の吸収性障壁構造体は、吸収領域及び障壁領域の上に実質的に重ねられる障壁領域を含む二層の積層体である。図２Ａは、この実施形態を概略的に図解し、そこでは吸収性障壁構造体１０は障壁層１２及び吸収層１４を含む。吸収層はバウンティー（Ｂｏｕｎｔｙ）（登録商標）ペーパータオル（プロクターアンドギャンブル社（Ｐｒｏｃｔｅｒ ａｎｄ Ｇａｍｂｌｅ Ｃｏｍｐａｎｙ）（オハイオ州シンシナティ（Ｃｉｎｃｉｎｎａｔｉ））により製造される）として商業的に入手可能な天然繊維のセルロースウェブである。ウェブは二重構造を持つ。全重量は約４３ｇｓｍであり、全厚さは約０．６８６ｍｍである。障壁層はポリプロピレンスパンボンド／メルトブロウン不織布ウェブ（ＢＢＡノンウオブンズ社（ＢＢＡ Ｎｏｎｗｏｖｅｎｓ）（サウスカロライナ州シンプソンビル（Ｓｉｍｐｓｏｎｖｉｌｌｅ））によりＭＤ２００５の名称で製造される）であり、坪量約２７ｇｓｍ及び厚さ約０．３０５ｍｍを有する。
【０２０２】
（実施例２）
この例では吸収性障壁構造体は三層構造を持ち、吸収性領域と向かい合う側に配置される第一及び第二障壁領域を含む。図２Ｂはこの実施形態を概略的に図解し、吸収性障壁構造体１０は二つの障壁層１２及び１６並びにこれら二つの障壁層の間の吸収層１４を含む。吸収層は二重のバウンティー（登録商標）ペーパータオルである。第一及び第二障壁層は、メルトブロウン（ＭＢ）ポリプロピレン不織布ウェブ（ジェンテックスコーポレーション（Ｊｅｎｔｅｘ Ｃｏｒｐｏｒａｔｉｏｎ）（ジョージア州バフォード（Ｂｕｆｏｒｄ））によりＰＰ−０１５−Ｆ−Ｎ）の名称で製造される）である。ＭＢ不織布ウェブは各々約１５ｇｓｍの坪量を有する。
【０２０３】
（実施例３）
この例では、第一障壁層は約１０ｇｓｍの坪量を持つ、ジェンテクス社（Ｊｅｎｔｅｘ）からのＭＢポリプロピレン不織布ウェブであり、第二障壁層は約１７ｇｓｍの坪量を持つマイクロデニール繊維から作成されるスパンボンド／スパンボンドポリプロピレン不織布ウェブ（ファーストクオリティーファイバーズノンウオブンズ社（（ＦｉｒｓｔＱｕａｌｉｔｙ Ｆｉｂｅｒｓ Ｎｏｎｗｏｖｅｎｓ）（ペンシルベニア州ヘイゼルトン（Ｈａｚｅｌｔｏｎ））からＧＣＡＳ１６００２１８４の名称で入手可能）であることを除いて、吸収性障壁構造体は実施例２に記載されるのと実質的に同じ構造を持つ。
【０２０４】
（実施例４）
この例では、第一障壁層は約５ｇｓｍの坪量を持つ、ジェンテクス社（Ｊｅｎｔｅｘ）からのＭＢ不織布ウェブであり、第二障壁層は約１０ｇｓｍの坪量を持つ、ジェンテクス社（Ｊｅｎｔｅｘ）からのＭＢ不織布ウェブであることを除いて、吸収性障壁構造体は実施例２に記載されるのと実質的に同じ構造を持つ。
【０２０５】
（実施例５）
この例では、第一障壁層は約１０ｇｓｍの坪量を持つ、ジェンテクス社（Ｊｅｎｔｅｘ）からのＭＢ不織布ウェブであり、第二障壁層は約５ｇｓｍの坪量を持つ、ジェンテクス社（Ｊｅｎｔｅｘ）からのＭＢ不織布ウェブであることを除いて、吸収性障壁構造体は実施例３に記載されるのと実質的に同じ構造を持つ。
【０２０６】
（実施例２ｂ）
この例では、吸収層は単層のバウンティー（ＢＯＵＮＴＹ）（登録商標）であることを除いて、吸収性障壁構造体は実施例２に記載されるのと実質的に同じ構造を持つ。
【０２０７】
（実施例３ｂ）
この例では、吸収層は単層バウンティー（ＢＯＵＮＴＹ）（登録商標）であることを除いて、吸収性障壁構造体は実施例３に記載されるのと同じ構造を持つ。
【０２０８】
（実施例２ｃ）
この例では、吸収層は単層バウンティー（ＢＯＵＮＴＹ）（登録商標）の二つの重ね合わせた層を含むこと以外は、吸収性障壁構造体は実施例２に記載されるのと実質的に同じ構造を持つ。
【０２０９】
（比較例）
比較例１はプロクターアンドギャンブル社（Ｐｒｏｃｔｅｒ ＆ Ｇａｍｂｌｅ Ｃｏｍｐａｎｙ）（オハイオ州シンシナティ（Ｃｉｎｃｉｎｎａｔｉ））から入手可能な二層バウンティー（ＢＯＵＮＴＹ）（登録商標）タオルである。
【０２１０】
比較例２は、欧州特許第９３４，７３５号及び欧州特許第９３４，７３６号に記載されるもののように表面の上に折り曲げた毛管を持つ成形されたフィルムである。成形されたフィルムはポリエチレンから作成され、トレデガーフィルムプロダクツコーポレーション社（Ｔｒｅｄｅｇａｒ Ｆｉｌｍ Ｐｒｏｄｕｃｔｓ Ｃｏｒｐｏｒａｔｉｏｎ）（インディアナ州テレホート（Ｔｅｒｒｅ Ｈａｕｔｅ））から入手可能である。
【０２１１】
比較例３は微小多孔性フィルムである。このフィルムは４０〜４５重量％炭酸カルシウム充填剤を持つポリエチレンから作られる。このフィルムはクロパイプラスチックフィルムプロダクツカンパニー社（Ｃｌｏｐａｙ Ｐｌａｓｔｉｃ Ｐｒｏｄｕｃｔｓ Ｃｏｍｐａｎｙ）（オハイオ州シンシナティ（ Ｃｉｎｃｉｎｎａｔｉ））から入手可能である。
【０２１２】
比較例４は、ファイストクオリティーファイバーズノンウオブンズ社（Ｆｉｒｓｔ Ｑｕａｌｉｔｙ Ｆｉｂｅｒｓ Ｎｏｎｗｏｖｅｎｓ）（ペンシルベニア州ヘイゼルトン（Ｈａｚｅｌｔｏｎ））からＧＣＡＳ１６００２１８４の名称で入手可能であるポリプロピレンＳＳ不織布ウェブである。
【０２１３】
比較例５は、ジェンテクスコーポレーション社（Ｊｅｎｔｅｘ Ｃｏｒｐｏｒａｔｉｏｎ）（ジョージア州バフォード（Ｂｕｆｏｒｄ））からＰＰ−０１５−Ｆ−Ｎの名称で入手可能なポリプロピレンＭＢ不織布ウェブである。
【０２１４】
実施例６
上記の例の特性は本明細書に開示する試験方法に従って試験される。三層構造体について、第一障壁層は試験中、吸収性コアに近接して配置される。試験結果は表１ａ及び表１ｂに要約する。
【０２１５】
【表１】

【表２】

表１ａの試験結果は、本発明が特性の所望の釣り合いを有する独特の構造体を提供することを示している。
【０２１６】
表１ｂの試験結果は、比較例が特性の所望の釣り合いを提供しないことを示している。バウンティー（ＢＯＵＮＴＹ）（登録商標）ペーパータオル（比較例１）は優れた空気透過性を持つが、液体不透過性に乏しい。微小多孔性フィルム（比較例２）は優れた液体不透過性を持つが、実質的に空気不透過性である。不織布ウェブ（比較例３〜５）は一般的状態で空気透過性及び液体不透過性である。しかし、不織布ウェブは衝撃及び／又は圧力状態で液体透過性になる。
【０２１７】
（実施例７）
この例では、実施例２に記載されるような三層構造を持つ吸収性障壁構造体は、外側カバー材と組み合わされ、そのカバー材は１６ｇｓｍのＳＢ層及び１１．５ｇｓｍのＭＢ層を持つポリプロピレンＳＭ不織布ウェブである。組み合わせの構造体は本明細書に記載する試験方法に従って試験される。試験結果は表２に要約する。
【０２１８】
【表３】

実施例２の吸収性障壁構造体と比較する時、組み合わせた構造体は液体不透過性及び衝撃下の湿潤通過への抵抗性は高いが、空気透過性は低い。全体的に、組み合わせた構造体は特性の所望の釣り合いも提供する。
【０２１９】
（実施例８）
この例では、実施例２の吸収性障壁構造体が実施例７による外側カバー材と組み合わされる。さらに孔あきフィルムは、実施例２の第二障壁層と実施例７の外側カバーとの間に配置される。孔あきフィルムは１１．７％の開放領域を持つポリエチレンから作られる。孔は六角形の形状の開口部である。本明細書で使用される孔あきフィルムは、ＢＰケミカルズ社（ＢＰ Ｃｈｅｍｉｃａｌｓ）（ドイツ、ワッセルブルグ（Ｗａｓｓｅｒｇｕｒｇ））により商品名（ＨＥＸ−Ｂ型４５１０９）で製造されている。トレデガーフィルムプロダクツコーポレーション社（Ｔｒｅｄｅｇａｒ Ｆｉｌｍ Ｐｒｏｄｕｃｔｓ Ｃｏｒｐｏｒａｔｉｏｎ）（インディアナ州テレホ−ト（Ｔｅｒｒｅ Ｈａｕｔｅ））によりＨＥＸ−Ｂの名称で製造される孔あきフィルムも、同じく本明細書での使用に好適である。
【０２２０】
吸収性障壁構造体、孔あきフィルム、及び外側カバーを含む全体的構造は、本明細書に記載する試験方法に従って試験され、孔あきフィルムを含まない実施例７と比較される。結果を次の表３に要約する。
【０２２１】
【表４】

孔あきフィルムの開放構造は、対流的空気透過性全体に実質的に影響を与えない。孔あきフィルムは特に衝撃状態下で構造全体の液体不透過性を低減する。結果は、孔あきフィルムの追加を含む構造全体でも特性の所望の釣り合いを達成することを示している。より重要なことには、孔あきフィルムは構造全体の拡散的ＭＶＴＲを低減する。故に透過性の独特の組み合わせは、構造体の外部表面上の湿気又は凝縮の低減を望ましく表す構造体を提供する。
【０２２２】
（実施例９）
この例では、吸収層は両面を疎水剤で表面処理したセルロースウェブ（つまり二層バウンティー（ＢＯＵＮＴＹ）（登録商標）タオル）である。表面処理法は国際公開第００／１４２９６号（ディアゴスティノ（Ｄ’Ａｇｏｓｔｉｎｏ）ら）に記載されているが、その明細書を参考として引用し本明細書に組み込む。使用する疎水剤は過フッ化炭化水素、つまりペルフルオロメチルシクロヘキサンである。処理されたセルロースウェブは、二つの障壁層の間に配置され、三層吸収性障壁構造体を形成する。例９ａは、処理されたバウンティー（ＢＯＵＮＴＹ）（登録商標）が未処理のバウンティー（ＢＯＵＮＴＹ）（登録商標）の代わりに吸収層として使用されることを除いて、実施例２と実質的に同じ構造を持つ。下記の表４は、未処理ウェブを使用する例と比較したこの例の特性を示す。
【０２２３】
【表５】

結果は、空気透過性が維持される一方、疎水性処理により液体不透過性は著しく増すことを示す。
【０２２４】
（実施例１０）
この例では、実施例３及び比較例２が試験方法Ｇ（圧縮後の空気透過性）により試験される。結果は下記の表５に要約される。
【０２２５】
【表６】

圧縮の結果として、本発明の吸収性障壁構造体の実施例３の空気透過性が実質的には変わっていないことを試験結果は示している。対照的に比較例２のような材料は空気透過性を優位に損失するが、それは圧縮下の構造的変化及び最初の構造に回復できないことによるものである。
【０２２６】
本発明の特定の実施形態について説明したが、本発明の主旨及び範囲を逸脱しない程度に様々な変更及び修正を行ってもよいことは当業者には明白であろう。
【図面の簡単な説明】
【図１】本発明の吸収性障壁構造体を含有する吸収物品の部分的に切開した上部平面図である。
【図２Ａ】障壁層及び貯蔵層を持つ本発明の吸収性障壁構造体の横断面図である。
【図２Ｂ】二つの障壁層の間に配置される貯蔵層を持つ本発明の吸収性障壁構造体の横断面図である。
【図３Ａ】図２Ａの吸収性障壁構造体の代替実施形態の横断面図である。
【図３Ｂ】図２Ａの吸収性障壁構造体の代替実施形態の横断面図である。
【図３Ｃ】図２Ａの吸収性障壁構造体の代替実施形態の横断面図である。
【図３Ｄ】図２Ａの吸収性障壁構造体の代替実施形態の横断面図である。
【図４Ａ】並ぶ配置で障壁領域及び貯臓器領域を持つ本発明の吸収性障壁構造体の上部平面図である。
【図４Ｂ】本発明の吸収性障壁構造体の代替配置の上部平面図である。
【図５】動的液体衝撃テスタの概略図である。[0001]
(Cross-reference of related applications)
This patent application claims priority to PCT application US 00/17084 filed on June 21, 2000 in the name of Sprengard-Eichel et al.
[0002]
(Field of the Invention)
The present invention relates to absorbent articles that provide excellent protection against wet passage under impact or sustained pressure, and thereby provide high convective airflow for skin health and comfort benefits. In particular, the present invention relates to absorbent barrier structures for such articles.
[0003]
(Background of the Invention)
Many known absorbent articles, such as diapers, incontinence articles, feminine hygiene articles, training pants, generally include a liquid permeable bodyside liner or topsheet and a vapor permeable liquid impermeable outer cover or backsheet. An absorbent core material located between the two. The bodyside liner allows body fluids to flow easily to the absorbent core. The absorbent core absorbs the liquids quickly. Therefore, excessive puddles of liquids do not form on the body surface of the absorbent article. The outer cover is generally liquid impermeable and does not leak from the absorbent article. However, since disposable absorbent articles may be worn for hours, after the absorbent article absorbs liquids, perspiration from the wearer's body and liquid vapor escaping from the absorbent core are absorbed by the absorbent core. Occasional entrapment in the space between the article and the wearer's skin will increase the relative humidity in the occluded area. As is known in the art, increased relative humidity causes discomfort and hyperhydration of the skin, which is prone to skin health problems, especially rashes and dermatitis due to other contact. .
[0004]
Such a backsheet is suitable for preventing leakage of bodily fluids (such as urine, menstruation or fecal matter) from the absorbent material to clothing outside the wearer. Unfortunately, the use of such impermeable backsheets results in high humidity inside the absorbent article when the absorbent article is used, resulting in a relatively high level of skin hydration.
[0005]
The problem of high relative humidity near the skin in absorbent articles has been addressed in the art through a number of means. For example, US Pat. No. 5,137,525 uses mechanical means to increase airflow in an article. Alternatively, for example, a breathable outer cover comprising a microporous film or a monolithic film allows the diffusion of air and water vapor, but has already been disclosed. WO 98/58609 discloses an absorbent article having good liquid retention in an absorbent core in combination with a water vapor permeable liquid impermeable barrier material for a backsheet. WO 00/10497, WO 00/10498, WO 00/10499, WO 00/10500, WO 00/10501 relate to breathable absorbent articles with the diffusion properties of wet articles. These disclosures show that high permeability in the absorbent core can be achieved, such as by piercing the absorbent core or creating a portion in the core that contains substantially less superabsorbent material than other portions of the core. An absorbent article having a region is disclosed. These publications disclose a mechanism for moving gas or vapor through an absorbent article by a diffusion mechanism, such as diffusion through the use of a microporous film. Since the diffusion mechanism is not very effective, the absorbent articles disclosed therein provide a relatively good humidity condition during wear unless large quantities of liquids such as urine are substantially filled into the article. obtain.
[0006]
However, these absorbent articles also significantly increase the relative humidity between the wearer's skin and the article when the article is filled.
[0007]
Another performance parameter of interest for filled / wet absorbent articles is that the movement of the wearer, such as sitting, walking, bending over, and falling, particularly when the article is subjected to pressure or impact forces, The ability to retain and prevent leaks. The prior art is to provide a perfect absorbent article that can retain liquids when filled to its absorption capacity, especially when the filled absorbent article is subjected to pressure or impact by the movement of the wearer. Also failed. As a result, the relative humidity within the diaper, on the one hand, is in a range generally accepted as comfortable, typically between about 30% to about 70%, more usually between about 30% to about 50%. There is a need for an absorbent article with a balance of properties that can be maintained at a constant level. Such absorbent articles must also have the ability to retain liquids without leakage, especially when the articles are filled with body fluids. Further, there is a need to provide an absorbent article that controls the relative humidity within the absorbent article by a convective transport mechanism. Further, there is a need for an absorbent article in which good local scene conditions are achieved by carefully designing the chassis elements.
[0008]
Generally, breathable polymer films have been used as outer covers for absorbent articles to reduce the level of humidity in the space between the absorbent article and the wearer's skin. Breathable films are generally composed of micropores and provide a level of diffusive air / vapor permeability that is substantially less effective than liquid impermeability and convective air / vapor permeability.
[0009]
Other disposable absorbent articles are designed to provide a breathable area in the form of a breathable panel or perforated opening in the backsheet or core to assist in ventilation of the garment.
[0010]
Articles that use perforated components or breathable panels often exhibit excessive leakage or wet passage of liquids from the article. In addition, movement of the wearer (eg, sitting, falling, walking, lying down) imposes physical activities on the absorbent article, such as impact, compression, bending, etc., which may lead to increased leakage and wet passage. There is. The leak / wet passage problem is exacerbated by higher impact or pressure, heavy waste and / or longer wear times.
[0011]
Alternatively, multilayer backsheets or outer covers have been used to address the wet passage problem. For example, breathable materials such as fibrous woven or nonwoven webs have been used for outer covers, either alone or in laminates with microporous films. The relative open structure of such materials allows air or steam to diffuse easily. The laminate may provide improved liquid impermeability and diffusive air / vapor permeability. The material may be treated to further improve liquid impermeability. However, the laminate still does not provide useful protection against impact and / or wet passage due to continuous pressure.
[0012]
Furthermore, transporting air or vapor through the stack by diffusive mechanisms is not as effective as transporting by convective mechanisms.
[0013]
An alternative to the wet passage problem is to improve the absorbent material and make little or no liquid contact the backsheet, thereby preventing wet passage. This is generally achieved by increasing the amount of absorbent material in the article. However, this method may result in increased thickness and reduced comfort of the article and reduced vapor / air permeability through the article.
[0014]
Another approach to the wet passage problem is to place the formed film between the core and the backsheet. Molded films with holes in the form of inclined cones are disclosed in WO 99/39672, WO 99/39673, and WO 99/39674. However, after compression or continuous pressure is applied, these formed films cannot maintain their formed shape and cannot provide the desired balance of fruit characteristics. Thus, although these molded films may appear to have material properties that provide air permeability and adequate leak protection, the series of steps of packing (shipping, shipping, And storage) are generally imposed and are not useful as components in absorbent articles that may be subjected to continuous pressure during use (eg, where the wearer sits).
[0015]
Thus, there is a need to have an absorbent article that provides comfort to the consumer by reducing the relative humidity within the absorbent article at the desired overall thickness and yet achieves useful wet pass protection. There is.
[0016]
There is also a need to provide an absorbent article that manages the relative humidity in the space between the article and the wearer's skin in order to maintain good skin health. Further, there is a need to control the relative humidity within the absorbent article with an effective convective transport mechanism, and optionally some diffusive transport mechanism may be incorporated as well.
[0017]
In addition, there is a need for an absorbent article in which careful design of the components of the article achieves optimal local scene conditions in the space between the article and the wearer's skin. In particular, there is a need for an absorbent barrier structure that provides the desired wet-pass protection and air / vapor permeability. Further, such absorbent barrier structures have a desired thickness for wearer comfort.
[0018]
In addition, compression and / or continuous pressure conditions for at least 24 hours without substantial loss of performance such as air permeability, liquid impermeability, and resistance to shock or leakage under continuous pressure. There is a need to provide an absorbent article comprising a barrier absorbent structure that can be exposed.
[0019]
(Summary of the Invention)
The present invention relates to an absorbent article having improved protection and comfort through the use of an absorbent barrier structure. This is achieved by the selection of individual components that meet specific requirements, the combination of which provides an absorbent article with the desired performance.
[0020]
Typical absorbent articles include an air / vapor permeable liquid impermeable outer cover, a liquid permeable bodyside liner or topsheet, an absorber between the outer cover and the bodyliner, and disposed between the outer cover and the absorber. Absorptive barrier structure.
[0021]
The absorbent barrier structure of the present invention has a balanced property between convective airflow and absorbent barrier properties. The convective airflow characteristics are effective to reduce the relative humidity in the space between the absorbent article and the wearer's skin. The combination of liquid absorption and liquid barrier properties provides protection against wet passage problems, and is particularly beneficial when the absorbent article is subjected to impact and / or continuous pressure.
[0022]
The absorbent barrier structure is a composite structure having at least one barrier region and at least one storage region. The barrier region resists the passage of liquid, such that the outflow of liquids from the absorbent core is substantially slowed or delayed so that the absorbent core acquires, arranges, and retains liquids to their full capacity. To allow time to be added. Suitable materials for the barrier region should have a head value of at least about 10 mbar. The storage area absorbs and retains any migratory liquids that escape from both the core and barrier areas, thereby adding additional protection to wet passage.
[0023]
Cooperatively, the area of the absorbent barrier structure effectively protects against wet passage problems, even under extreme conditions such as impact or sustained pressure.
[0024]
Absorbent barrier structures generally have a head value of at least about 10 mbar, a convective air permeability of at least about 10 darcy / mm, a dynamic liquid impact value (LIT) of less than about 10 g per square meter, and at least It has an absorption of about 1 g / g.
[0025]
In one embodiment, the absorbent barrier structure comprises one barrier layer disposed near the garment facing surface of the absorbent core and one storage layer disposed near the garment facing surface of the barrier layer. With layers. An additional barrier layer may be located on the opposite side of the storage layer.
[0026]
In other embodiments, the absorbent article may further include a moisture management layer.
[0027]
(Detailed description of the invention)
(Definition)
As used herein, the term "absorbent article" refers to a device that absorbs and traps body effluents, particularly the various effluents that are placed on or near the wearer's body and exit the body. A device that absorbs and contains objects. Absorbent articles may include diapers, training pants, adult incontinence underwear, feminine hygiene products, breast pads, and the like.
[0028]
As used herein, the term "body fluids" or "body excretion" includes, but is not limited to, urine, blood, vaginal excretion, sweat, and fecal material.
[0029]
The term "disposable" as used herein is not intended to be laundered or otherwise restored or reused as an absorbent article (i.e., discarded after use, and preferably reused, buried, (If not otherwise intended to be discarded in an environmentally compatible manner).
[0030]
The term “region” as used herein refers to a range or region that includes a material that is physically, chemically or visually distinguishable from surrounding or adjacent materials. Various regions of the material may include transition regions between. These regions may be arranged in the z dimension or the xy dimension. As used herein, the term “z-dimension” refers to a dimension orthogonal to the length and width of a structure or article. The z dimension typically corresponds to the thickness of the structure or article. The term "xy-dimension" as used herein refers to a plane orthogonal to the thickness of the member, core, or article when the member, core, or article is flat.
[0031]
This xy dimension typically corresponds to the length and width of each flat structure or article.
[0032]
As used herein, the term "single structure" includes substances with different properties that are joined together to form a complete unity, such that the material is substantially physically inseparable Refers to a structure, where a single structure exhibits properties due to the combination of materials therein. The materials may be arranged in a face-to-face relationship in the z-dimension or in a parallel relationship in the xy-dimension.
[0033]
As used herein, the term "functionally related" refers to a structure that includes different materials that are placed at least partially in contact with each other during use. The materials are physically separable, each exhibiting individually measurable properties. The materials may be arranged in a face-to-face relationship in the z-dimension or in a parallel relationship in the xy-dimension.
[0034]
The term "stick" as used herein refers to different materials that are attached (adhesively or adhesively) at least in part. The attached portions may be irregular or have patterns such as stripes, spirals, dots, and the like. The attached portion may be located at the periphery, the entire surface area, or both. Any suitable attachment means known in the art may be used, including adhesives, heat, pressure, pressure welding, ultrasonics, chemistry (by hydrogen bonding or other cohesion), mechanical manipulation (eg, Fasteners, meshing), hydraulic, vacuum, and combinations thereof.
[0035]
As used herein, the term "composite structure" refers to a multi-region structure in which the material containing the region may be functionally related or adhered. These regions may be in intimate contact, and the composite has a single structure. Furthermore, these regions may be arranged in a layered (face-to-face) arrangement or in a parallel arrangement.
[0036]
As used herein, the term "absorbent core" is a component of an absorbent article that is primarily responsible for the fluid handling properties of the article, including acquiring, transporting, distributing, and storing body fluids. Point to. Thus, the absorbent core generally does not include a topsheet, backsheet, or outer cover of the absorbent article.
[0037]
As used herein, "pulp" or "cellulose fiber" refers to natural fibers derived from trees or vegetation (eg, hardwood fibers, softwood fibers, hemp, cotton, flax, African honeysuckle, milkweed, straw, bagasse, etc.) Processed / regenerated fibers (eg, Rayon®), or chemically derived fibers (eg, cellulose esters), and combinations thereof. Suitable hardwood fibers include eucalyptus fibers. Suitable hardwood fibers may be prepared by the kraft process or various chemical pulping processes.
[0038]
Suitable softwood fibers include southern US softwood (SS) fibers and northern US softwood (NS) fibers. Softwood for use herein is chemically (eg, without limitation, kraft pulp) or mechanically pulped (eg, without limitation, thermochemical mechanical pulp (CTMP) and thermomechanical pulp (TMP)). It is possible.
[0039]
As used herein, a "nonwoven web" refers to a web having a structure of individual fibers that intervenes to form a matrix but is not in a recognizable, repetitive manner. The nonwoven web may be formed by various methods known in the art, such as, for example, meltblowing, spunbond, wet, air laying, and various bond card methods.
[0040]
As used herein, the term "spunbond web" refers to extruding a molten thermoplastic material as filaments from a plurality of thin capillaries of a spinneret having a circular or other configuration, and then reducing the diameter of the extruded filaments by a fluid. Refers to a web having fibers formed by rapid reduction by drawing or other well-known spunbond mechanisms. Spunbond fibers are cooled when placed on the collection surface and are generally not tacky. Spunbond fibers are generally continuous, often having an average value between 20 and 30 microns.
[0041]
As used herein, a `` meltblown web '' is a process in which a molten thermoplastic material is passed through a plurality of thin, usually circular capillaries as a molten thread or filament, and the molten filament is reduced in diameter to reduce its diameter. Refers to a web with fibers formed by extruding into a converging, rapidly heated gas / air stream. The reduction in fiber diameter is substantially greater than the reduction in fiber diameter of the spunbond process, resulting in microfibers having an average fiber diameter greater than 0.2 microns, typically in the range of 0.6 to 10 microns. . The meltblown fibers are then carried by the high velocity gas stream and deposited on the collection surface, forming a web of randomly distributed fibers. Various meltblowing methods are known in the art.
[0042]
The following detailed description of the absorbent barrier structure of the present invention relates to disposable diapers. However, it is readily apparent that the absorbent barrier structure of the present invention is also suitable for use in other absorbent articles such as feminine hygiene products, training pants, incontinence articles and the like. It is also clear that the absorbent barrier structure of the present invention is suitable for use in other hygiene or health care products such as bandages, wound dressings, wipes, bibs, surgical sheets, surgical gowns and the like. is there.
[0043]
(Barrier structure or absorbent barrier structure)
The present invention provides a barrier structure that allows convective air or water vapor transport through this structure. In particular, the structure of the present invention achieves the desired convective air flow without sacrificing barrier protection against wet passage. When the barrier structure is included in the absorbent article, the resulting absorbent article exhibits an effective reduction in relative humidity in the space between the absorbent article and the wearer, and thus enhances skin health and wearer comfort. Improve and / or maintain.
[0044]
Convective transport capacity is different from diffuse transport capacity. Convective transport is carried by gas or pneumatic pressure differences and is generally a higher transport rate than diffusive transport carried by uneven molecular movement. Common examples of diffusive transport are through pores in a microporous film, such as those known in the art as backsheet materials, or Hytrel® (DuPont (Delaware) (Available from Wilmington, U.S.A.), including the transfer of moisture through molecular structures of non-porous monolithic films, such as those made from. Convective transport, on the other hand, is governed by the pneumatic pressure difference between the inside and outside of the article. The local pressure (i.e., the local pressure in the space between the article and the wearer) and the environmental pressure (i.e., outside the article) are substantially the same, but small changes in local pressure Convective airflow may generally be caused to pass through the gap between the person and the article. Factors that may lead to convective transport include, but are not limited to, movement by the wearer, small pressure differences between the local environment and the outside environment, and / or temperature differences.
[0045]
With the advances made in absorbent articles, absorbent articles using elastic materials and components now provide a tighter seal (i.e., less gap) to the body of the wearer and outwardly. Minimize fluid leakage. As a result, convective airflow through the gap is substantially reduced, resulting in a moist, warm local environment in the space between the article and the wearer. The absorbent core is generally air permeable, but when the core absorbs (ie, is filled with) liquid, the air permeability generally decreases. The liquid of the filled core can generally be drained relatively easily (ie, becomes air permeable) by the draining means. Alternatively, the openness of the core structure can be achieved by choosing a particular arrangement of the permeable material.
[0046]
These drained or open cores generally require a leak proof component, typically a microporous film backsheet or a relatively thick nonwoven, that provides liquid impermeability and leak proofing. I do. However, these liquid impermeable components reduce the air permeability of the article. In contrast, the barrier structure of the present invention allows for convective airflow through the structure itself.
[0047]
The barrier structure of the present invention also provides liquid absorption and good liquid holding capacity. Therefore, it is also an absorbent barrier structure. The movement of the wearer, such as sitting, falling down, lying down, bending over, walking, may cause pressure on the filled (i.e., wet with body fluids) absorbent and / or nearby absorbent barrier structures. This ability to retain liquid is particularly beneficial when potential / force is to be applied. Thus, when the absorbent barrier structure is included in an absorbent article, the resulting absorbent article not only provides effective convective airflow, but also provides effective protection against wet passage when the article is subjected to impact forces. .
[0048]
Generally, the absorbent barrier structure is located between the absorbent core and the outer cover, preferably near the garment-facing surface of the absorbent core. Absorbent barrier structures are composite structures that include a plurality of individual regions of a material that are joined or functionally related.
[0049]
Alternatively, these multiple regions may be combined with a single structure to physically separate the individual regions. The individual regions of the absorbent barrier structure may or may not be coextensive depending on the requirements of the absorbent article. The individual regions may be joined by attachment means such as those known in the art.
[0050]
As used herein, the term "joining" refers to a configuration in which one member is directly secured to another member by directly securing one member to another member, and one member is secured to an intermediate member; The intermediate member includes a configuration in which one member is then fixed directly to another member by being secured to the other member. For example, the plurality of regions may be secured together by a single continuous layer of adhesive or a separate line, spiral, droplet, or bead array of adhesive. The adhesive may be applied continuously or intermittently.
[0051]
For example, each application of the adhesive is separated from one another by the selected length over the length of the absorbent barrier structure. Adhesive is applied to handle the web during the assembly process, joining the multiple regions. Preferably, an adhesive is applied to a portion of the surface of the absorbent barrier structure, leaving sufficient open (ie, adhesive free) surface area for air / vapor permeability. Alternatively, an adhesive may be applied to modify the liquid impermeability. Generally, the open or adhesive-free surface area will be no more than about 50%, preferably no more than about 70%, more preferably no more than about 80%, and most preferably no more than the total surface area of the absorbent barrier structure. About 90%. Suitable adhesives are described in B. Manufactured by Fuller Company (St. Paul, MN), marketed as HL-1258, and by Ato-Findley Inc. (Milwaukee, Wis.) It is manufactured and marketed under the trade name H2031F.
[0052]
In one embodiment, the adhesive is applied in a striped fashion along the periphery of the area. In another embodiment, when the adhesive is used in a diaper, it is applied in a plurality of stripes that place a space that is aligned with the longitudinal centerline of the diaper. In another embodiment, the adhesive is applied to the web in three stripes along the diaper's longitudinal centerline. Each stripe is 22 mm wide (lateral to the diaper) and the two outer stripes are located at or near the longitudinal periphery (about 4 mm apart).
[0053]
The adhesive is generally applied to the surface of at least one of the webs containing the absorbent barrier structure from its softened or molten state. The adhesive is heated to at least above its softening temperature before being applied to the substrate surface. Once applied, the adhesive cools and is allowed to cure / set. Various methods are known for softened or molten state applications. Particularly suitable methods for use herein include, but are not limited to, spraying, drip, gravure transfer, and extrusion.
[0054]
Alternatively, the attachment means may be a thermal bond, a pressure bond, an ultrasonic bond, a mechanical bond (eg, by interlock, cohesion, charge or electrostatic charge), or any other suitable attachment means or known in the art. May be included.
[0055]
The individual regions may be arranged in layers, with the individual regions being in intimate operable contact with at least a portion of an adjacent layer. Such contacts may be irregular or have a regular pattern such as dots, stripes, and the like. Preferably, each layer is connected to at least a portion of the adjacent layer of the absorbent barrier structure by a suitable securing and / or attaching means such as an ultrasonic bond, an adhesive bond, a mechanical bond, or a hydroneedling ring. . In other embodiments, the individual regions may be operatively placed in intimate contact along at least a portion of the boundary of an adjacent layer of the absorbent barrier structure.
[0056]
The absorbent barrier structure of the present invention has a convective air permeability of at least about 1 Darcy / mm, preferably at least about 10 Darcy / mm, more preferably at least about 30 Darcy / mm, and most preferably at least about 50 Darcy / mm. It may be configured to have a property. Convective air permeability is particularly effective in removing vapors from the interior of the absorbent article, thus reducing humidity in the local environment in close proximity to the skin. Thus, the absorbent barrier structure reduces the incidence of skin irritation or rash, promotes skin health and provides better comfort.
[0057]
While liquids are primarily absorbed by the absorbent core, the absorbent barrier structure provides additional leak protection against migrating liquids that are not absorbed or released from the absorbent core. Therefore, the absorbent barrier structures of the present invention need to have minimal liquid absorption.
[0058]
Liquid absorbency may vary depending on the material used for the absorbent structure, and the surface tension of the liquid is tested for absorbency and the contact angle between the test liquid and the material. Absorbent barrier structures suitable for use herein generally will be at least about 1 g / g, generally about 1 to about 100 g / g, preferably about 5 to about 50 g / g, more preferably about 5 g / g. It has an absorbency of 10 to about 30 / g (as measured by Test Method G using a 0.2% by weight Triton® solution).
[0059]
To provide additional leakage protection, the absorbent barrier structure must also have liquid retention capabilities, especially under shock and / or continuous pressure conditions. This property is particularly advantageous in absorbent article applications. If the absorbent article is wet, movement of the wearer, such as sitting, falling, lying down, or rolling, may squeeze out the absorbed liquids from the absorbent core, resulting in leakage from the article. Occurs. Hence, the absorbent barrier structure of the present invention is preferably about 30 g / m2. ² Less than about 20 g / m ² Less than about 15 g / m ² Less than about 10 g / m ² Less than, most preferably about 6.5 g / m ² With a liquid impact value of less than (measured by test method C).
[0060]
Similarly, for leak protection performance, the absorbent barrier structure must have some resistance to liquid permeation. Thus, the absorbent barrier structure of the present invention has a water head (as measured by Test Method B) of at least about 10 mbar, preferably at least about 30 mbar, more preferably at least about 50 mbar, and most preferably at least about 75 mbar. )have. In some embodiments, the absorbent barrier structure has a head value in the range of about 30 to about 100 mbar.
[0061]
The absorbent barrier structure of the present invention also has the desired leak protection due to static liquid transfer values (measured by Test Method D). In this regard, the absorptive barrier structure of the present invention can provide about 45 g / m 15 minutes after impact. ² Less than, preferably about 30 g / m ² Less than about 20 g / m ² Less than, most preferably 13 g / m ² With a static liquid transfer value of less than. In addition, the absorbent barrier structure of the present invention can provide about 50 g / m 60 minutes after impact. ² Or less, preferably about 35 g / m ² Or less, more preferably about 20 g / m ² Has the following static liquid transfer values:
[0062]
In another embodiment, there was no substantial change in barrier properties after the absorbent barrier structure was subjected to a compression state as described in Test Method F below. Structural integrity during compression and during recovery after compression is important for practical purposes. Absorbent articles are generally packaged in a compressed state for shipping and storage. When the product is ultimately removed from compression for its intended use, a material or structure that cannot recover to its pre-compression state may not be able to provide the originally designed properties. The absorbent barrier structure of the present invention should generally have a reduction in air permeability after compression of less than 35%, preferably less than 25%, and most preferably less than 15%. In a preferred embodiment, the absorbent barrier structure has a compressed air permeability as disclosed above after 7 days, preferably 30 days, more preferably 90 days.
[0063]
The thickness and basis weight of the absorbent barrier structure may vary depending on the materials used, desired properties, intended use, configuration, and the like. For example, the thickness and / or basis weight may be determined by the diffusive and / or convective air permeability between the interior and exterior of the article, the absorption and / or leakage of the article, the suitability of the article to the body of the wearer. May affect wearer comfort as well as similar effects generally related to structure thickness. Generally, the absorbent barrier structures of the present invention intended for use in absorbent articles have a thickness of less than about 1.5 mm, preferably less than about 1.2 mm, more preferably less than about 1.0 mm. . A suitable absorbent barrier structure thickness for use in an absorbent article should also have a minimum thickness of greater than about 0.1 mm, preferably greater than about 0.2 mm. In addition, absorbent barrier structures of the present invention suitable for use in absorbent articles generally have a thickness of about 20 gsm (g / m ² ) To about 200 gsm (g / m ² ), Preferably about 30 gsm (g / m ² ) To about 150 gsm (g / m ² ), More preferably about 40 gsm (g / m ² ) To about 120 gsm (g / m ² ), Most preferably about 50 gsm (g / m ² ) To about 100 gsm (g / m ² ).
[0064]
Absorbent barrier structures generally include two regions, a barrier region and a storage region. The barrier region is "substantially impermeable" to liquids, including water, urine, menses, and other bodily fluids. The term "substantially impermeable" means that the barrier region exhibits resistance to liquid penetration, but does not necessarily eliminate wet passage of liquid. In other words, the liquid is able to pass and flow through the barrier region under certain circumstances, such as impact force, applied high pressure, or pressure that lasts for a period of time (ie, is continuously applied). is there. The storage area is liquid absorbing. When the storage area is located in close proximity to the barrier area, any wet passage and / or leakage from the barrier area is absorbed by the storage area. In addition, the storage area also absorbs migrating liquids from the absorbent core. Thus, due to the combination of the barrier region and the storage region, when exposed to liquids, the barrier region provides resistance to wet passage of the liquid, and the storage region breaks through the resistance of the barrier region to allow any passage. Achieve a unique balance of properties that absorbs migrating liquids. That is, the absorbent area provides additional protection against the problem of wet passage of liquid. When the absorbent barrier structure of the present invention is placed in close proximity to a filled absorbent core, especially when the liquid filling level is high and / or when the filled absorbent core has a sudden high impact or continuation. Provides additional protection against wet passage when subjected to varying forces / pressures.
[0065]
This added wet-pass protection is particularly beneficial in diapers, training pants, pull-on diapers or adult incontinence products, where the level of liquid filling can be quite high (compared to feminine hygiene products). There is also a high probability of sudden shock or sustained pressure (eg, a baby or incontinent adult falling, sitting, rolling, sleeping). The absorbent barrier structure of the present invention is also advantageous when the absorbent core is subject to jets of liquids. The resistance to liquid wetting passage provided by the barrier region helps to temporarily slow the jet of liquids and collects as much liquid as possible at the interface between the absorbent core and the barrier region. The slow flow and reservoir provide additional time for the absorbent core to acquire liquids and place them in other areas of the core beyond the point of acquisition. As a result, the absorbent core can achieve its sufficient absorption.
[0066]
The absorbent barrier structure of the present invention can be more clearly understood with reference to the following illustrative figures. FIG. 2A is a cross-sectional view of one embodiment of an absorbent barrier structure of the present invention. The absorbent barrier structure 10 includes a barrier layer 12 and a storage layer 14. Optionally, an additional barrier layer 16 as shown in FIG. 2B may be located on the opposite side of the storage layer 14 so that the storage layer 14 is sandwiched between the barrier layers 12 and 16. The first and second barrier layers may be made from the same or different fibrous webs (in terms of web composition, basis weight, thickness, porosity, fiber denier, material, etc.).
[0067]
Various arrangements of the barrier region and the storage region are shown in FIGS. 3A to 3D. In FIG. 3A, a number of barrier regions 12 and storage regions 14 are arranged in a side-by-side relationship, with barrier regions 12 and storage regions 14 forming preferred stripes. In FIG. 3B, the barrier region 12 is a continuous web, and the storage region 14 is arranged in a discontinuous pattern adjacent thereto, such as stripes, circles, ellipses, squares, and the like. In FIG. 3C, the storage area 14 is a continuous web, and the barrier area 12 is arranged in a discontinuous pattern adjacent to it, such as stripes, circles, ellipses, squares, and the like. In FIG. 3D, discontinuous barrier regions 12 overlap at least partially discontinuous storage regions 14, each of which may have a shape such as stripes, circles, ellipses, squares, and the like.
[0068]
In all of the embodiments depicted in FIGS. 2A-3D, at least a portion of the barrier region is located proximate the garment-facing surface of the absorbent core. In one embodiment, the absorbent barrier structure may extend through substantially all of the absorbent core, or the absorbent barrier structure may have stripes or stripes extending into a portion of the absorbent core. It may be a spot. In other embodiments, the absorbent barrier structure may extend beyond the outer edge of the absorbent core, or may extend only through the length and width of the central portion of the absorbent core. . In a preferred embodiment, the barrier region and the storage region are arranged in a layered relationship, with the barrier layer being located immediately adjacent the garment-facing side of the absorbent core. Features in which the barrier region has at least the same length and width as the absorbent core are highly preferred. Further, the storage area need not have the same dimensions as the barrier area.
[0069]
(Storage area)
The storage area must be able to absorb, spread, and retain liquids such as urine, blood, and other bodily discharges. The storage area has a garment-facing surface, a body-facing surface, front and back edges, and side edges. The storage area absorbs and retains migrating liquids that escape from other components such as the absorbent core and barrier area. Therefore, the storage area provides additional protection against wet passage.
[0070]
The thickness and basis weight of the storage area may vary depending on the material used, desired properties, intended use, openness of the configuration, and the like. In particular, the thickness of the storage area is similar to the comfort of the absorbent article, as well as the air / gas permeability, the absorption and / or leakage protection of the barrier absorbent structure, and the compatibility and thickness of the structure May affect similar effects generally associated with Thus, the storage area generally has a thickness of less than about 1.5 mm, preferably less than about 1.0 mm, more preferably less than about 0.8 mm. The storage area must also have a minimum thickness to provide adequate absorption and structural integrity. The minimum thickness of the storage area is generally at least about 0.2 mm, preferably at least about 0.1 mm, more preferably at least 0.05 mm, most preferably at least 0.02 mm. Further, the basis weight of the storage area is generally about 5 gsm (g / m ² ) To about 120 gsm (g / m ² ), Preferably about 10 gsm (g / m ² ) To about 100 gsm (g / m ² ), More preferably about 30 gsm (g / m ² ) About 80 gsm (g / m ² ) Range.
[0071]
When compared to an absorbent core, the storage area absorbs fluids more easily (ie, wicks fluid more quickly) and releases fluids more easily. The storage area is generally at least about 1 g / g, preferably at least about 5 g / g, more preferably at least about 5 g / g using 0.2 wt% Triton® as the test fluid according to Test Method G. Has an absorbency of at least about 10 g / g. Preferably, the absorbency of the storage area is less than about 30 g / g, more preferably less than about 20 g / g. Further, the storage area should have at least about 20%, preferably about 30% less absorbency than the absorbent core.
[0072]
The storage area may be of any shape with an open structure, so that the air or gas permeability of the storage area is at least equal to that of the resulting absorbent barrier structure. The convective air / vapor permeability of the storage area is generally at least about 1 Darcy / mm, preferably at least about 10 Darcy / mm, more preferably at least about 30 Darcy / mm, and most preferably at least about 50 Darcy / mm. It is.
[0073]
Further, the openness of the structure may be increased by retaining or absorbing fluids in the gaps of the open structure. Suitable open structures may include fibrous webs (eg, woven or nonwoven webs), absorbent foams (eg, porous or reticulated foams), fibrous masses, and the like.
[0074]
In one embodiment, the storage area is made from a fibrous web. The fibrous web that constitutes the storage area need not necessarily contain absorbent fibers, as long as the web is absorbent. Therefore, the constituent fibers are simply hydrophilic fibers, and may not themselves have any absorbing power.
[0075]
Storage areas include cellulose fibers; natural wood pulp; synthetic fibers made from hydrophilic polymers such as polyesters and polyamides (such as nylon); hydrophobic fibers such as polyolefins which have been surface treated to improve their hydrophilicity. Fibers; or may be made from a wide variety of hydrophilic fibers, such as bicomponent fibers, any combination of materials such as layered fibers. In one embodiment, the storage area is made primarily of cellulosic fibers that are predominantly hydrogen bonded to each other. Cellulose fibers may be raw or processed, and may be chemically stiffened, modified, or crosslinked. The processed cellulosic fibers may include commercially available fibers made from regenerated cellulose, such as nylon, or derived cellulose. In a preferred embodiment, the storage area may consist of at least about 70%, preferably at least about 80%, more preferably at least about 90% by weight of cellulosic fibers.
[0076]
Alternatively, the storage area may consist of about 95-100% by weight cellulosic fibers.
[0077]
In other embodiments, the storage area may be in the form of a single or multilayer tissue, a creped tissue, a mass of tissue, and an air felt mat. The high wet strength tissue may also be used as a storage area. In other embodiments, the storage area may be of any shape having an open structure, whereby body fluids are retained or absorbed in the narrow gaps of the open structure. Furthermore, the space and surface material of the intermediate layer may additionally provide an intervening liquid holding space, which increases the absorption of the storage area.
[0078]
The storage area may include a supplemental chemical adhesive as is well known in the art. For example, the storage area may include a chemical adhesive such as vinyl acrylic copolymer, polyvinyl acetate, crosslinkable polyamides, polyvinyl alcohol, and the like. Additionally, wet strength resins and / or resin binders may be added to improve the strength of the cellulosic web. Useful binders and wet strength resins are, for example, Kymene® available from Hercules Chemical Company, and Parez available from American Cyanamid, Inc. (Parez) (registered trademark). If an open or loose fibrous web is desired, crosslinkers and / or wettable powders may be added to the pulp mixture to reduce the degree of hydrogen bonding. An exemplary bond weakener is available from Quaker Chemical Company (Conshohocken, PA) under the trade name Quake 2008. The storage area may contain up to 5% by weight, and optionally up to about 2% by weight, of a chemical adhesive to provide the desired benefit. The storage area generally contains a high wet strength tissue. Alternatively, the storage area may comprise a web of synthetic fibers. The storage area may adhere to the barrier area or other component of the diaper structure, such as with an adhesive.
[0079]
Suitable materials for the storage area are commercially available consumer paper towels manufactured by The Procter & Gamble Company (Cincinnati, Ohio), Bounty ( (Registered trademark) or a cellulosic fibrous web such as Hi-Dry (registered trademark) manufactured by The Kimberly-Clark Corporation.
[0080]
Suitable fibrous webs may have a single-layer or multilayer structure. The term "layer" as used herein means that the individual webs are arranged in a substantially continuous face-to-face relationship to form a multi-layer web. In addition, a single web may form two layers, for example, by folding on itself. In a multi-layer construction, the individual webs are at least partially joined, generally by point bonding, with or without an adhesive.
[0081]
Multi-layer structures have been found to provide higher resistance to breakthrough of liquids at unit basis weight than single-layer structures. Further, the absorbency of a two-layer fibrous web is at least twice that of a single-layer fibrous web at a unit basis weight. Without being bound by theory, it is believed that the intervening spaces (ie, structural voids) between the layers provide additional liquid holding space, and thus provide higher absorption. In addition, post-treatment of the cellulosic web, including but not limited to drilling, creping, embossing, or otherwise weaving, increases the absorbency of the web. Fibrous webs with perforated or textured surfaces exhibit higher absorbency, presumably due to microvoids and / or voids created by the treatment. In a preferred embodiment, the storage area is made of a fibrous web having at least two layers of textured surface structure. In addition, certain additives such as bond weakeners also increase the absorbency of the web by reducing the adhesion of the intermediate fibers (eg, hydrogen bonding between cellulosic fibers), thereby reducing the compressed fibrous network in the web. May be loosened. The resulting web openness provides more gaps for holding liquids, which increases the web's absorbency.
[0082]
In alternative embodiments, other types of wettable and / or hydrophilic fibrous materials may be used to form the storage area of the absorbent barrier structure. Representative fibers include essential fibers such as cellulose or processed cellulose fibers, including regenerated or derived cellulose fibers, commercially available as rayon® fibers, viscose® fibers. Naturally occurring organic fibers, polyesters, polyamides, copolymers thereof, polyvinyl alcohols, polyalkylene oxides and mixtures of these polymers inherently wettable materials made from highly wettable materials. Synthetic fibers made from certain thermoplastic polymers, as well as synthetic fibers made from non-wetting thermoplastic polymers such as polyethylene, polypropylene, polybutylene and other polyolefins, which may be hydrophilized by suitable means. These non-wetting fibers may be hydrophilized by treatment with a surfactant or surfactant having a suitable hydrophilic function, or by a sheath. These non-wetting fibers may have better wettability by attaching a hydrophilic function to the polymer chains. Suitable hydrophilic functionality includes, but is not limited to, acrylic, methacrylic, ester, amide, and mixtures thereof.
[0083]
The storage area contains additives such as chemical adhesives, crosslinkers, wet strength resins, bond weakeners, liquid or moisture absorbers, odor absorbers, antimicrobial agents, colorants, hardeners, and mixtures thereof. You may. Liquid or moisture absorbents include clay, silica, talc, diatomaceous earth, perlite, vermiculite, carbon, kaolin, mica, barium sulfate, aluminum silicate, sodium carbonate, calcium carbonate, other carbonates, superabsorbent polymers, Or other permeable liquid retaining agents, and mixtures thereof.
[0084]
In one embodiment, the storage area is coated over the fibers, mixed with the fibers in situ, or additionally contains superabsorbent polymers made into the fibers or particles.
[0085]
(Barrier area)
The barrier region preferably has "barrier-like" properties, which provide resistance to liquid wet passage. Barrier properties are generally measured by Test Method B (head pressure test) described below. The head value of the barrier region needs to be higher than the head value of the absorbent core and the storage region. Barrier region materials suitable for use herein should exhibit a head value of at least about 10 mbar, preferably at least about 30 mbar, more preferably at least about 50 mbar, and most preferably at least about 75 mbar. In some embodiments, a suitable barrier region has a head value from about 30 to about 100 mbar.
[0086]
Further, the barrier region should not substantially reduce the air / vapor permeability of the absorbent article. Moreover, the barrier region should have a convective air permeability of at least about 10 Darcy / mm, preferably at least about 30 Darcy / mm.
[0087]
The head value of a fibrous web increases with smaller fiber diameters, higher fiber densities, higher basis weights, or combinations thereof. Suitable fibrous webs for the barrier region generally have a basis weight of at least about 2 gsm, preferably about 5 to about 100 gsm, more preferably about 10 to about 75 gsm, and most preferably about 15 to about 55 gsm.
[0088]
The thickness of the barrier region may vary depending on the material used, desired properties, intended use, configuration, and the like. In particular, the thickness of the barrier region will determine the air / gas permeability, the absorption and / or leakage protection of the barrier absorbent structure, as well as the comfort and conformability of the absorbent article, and generally the thickness of the structure May affect similar effects. Thus, the barrier region generally has a thickness of less than about 1.5 mm, preferably less than about 1.0 mm, more preferably less than about 0.8 mm, and most preferably less than about 0.5 mm.
[0089]
It has been found that some materials that do not appreciably limit the air permeability of an absorbent article in the dry state significantly reduce the air permeability of the article when the absorbent core is filled with liquids. Therefore, when the absorbent article is in a dry state, materials suitable for use in the barrier region should allow for adequate water vapor transmission, and the air / water vapor permeability of the diaper should be comparable to a diaper without barrier region material. There is virtually no change. When the absorbent core is filled to absorb liquids released from the body, the barrier region may reduce the air / vapor permeability of the absorbent article, which may occur on the garment side of the outer cover. Reduce or eliminate some moisture.
[0090]
To provide the desired head or "barrier-like" properties, suitable materials are not required properties, but are preferably hydrophobic. Representative hydrophobic polymeric materials are generally polyolefins such as polyethylene, polypropylene, polybutylene, and copolymers thereof. Non-hydrophobic materials, such as polyamides, polyesters, polyalkylene oxides, polyvinyl alcohols, may be treated with a suitable hydrophobic agent to achieve the desired hydrophobicity. Moreover, the storage layer may be treated on at least one surface to improve its hydrophobicity and thus improve its barrier properties.
[0091]
The treatment for improving hydrophobicity may include chemical, radiation, plasma, or a combination thereof. Further, surface treatment to improve surface properties may be accomplished by coating the surface, premixing with the hydrophobic agent, or in situ mixing the hydrophobic agent coating the surface with further treatment.
[0092]
In one embodiment, the fluorocarbon treatment of the web material provides the desired hydrophobicity, such that the web exhibits the desired water resistance properties as measured, for example, by a head test. In other embodiments, fluorocarbon treatment using a plasma or similar technique provides a very thin hydrophobic coating, so that the air permeability of the treated web is not substantially changed. If desired, the treatment may be applied to only a portion of the substrate surface. These treatments may be applied to materials that are suitable for use herein as barrier areas, storage areas, outer covers, or other diaper components. Suitable substrate materials for this treatment include, but are not limited to, nonwoven webs, cellulosic webs, thermoplastic films, modified / processed films (eg, molded, perforated), and the like. Typical surface treatments using fluorocarbons are described in US Pat. No. 5,876,753, issued to Timmons et al. On Mar. 2, 1999, and Gleason on Mar. 30, 1999. U.S. Pat. No. 5,888,591 to Gleason et al .; U.S. Pat. No. 6,045,877 to Gleason et al. On Mar. 7, 1999. Published in WO 99/20504 by D'Agostino et al. Published in WO 00/14296 by D'Agostino et al. Published on March 16, 2000. However, each specification is cited by reference and incorporated herein.
[0093]
Other surface coating methods using silicone or fluorochemicals are known in the art and may be used herein. Conventional coating or surface treatment methods generally fill voids in the web, thereby reducing its air permeability.
[0094]
Coating methods for providing hydrophobicity to a substrate without reducing air permeability can be found in US Pat. No. 5,322,729 and WO 96/03501, with reference to each specification. Incorporated herein by reference.
[0095]
The barrier region may be a meltblown (MB) web; a spunbond (SB) web, especially a fine fiber spunbond web such as one having a fiber denier of about 2 or less; a meltblown and spunbond fiber, commonly known as an MS nonwoven fabric Composite web with a layer of SMS nonwoven; bonded card web; airlaid web; hydroentangled web; knit web; and fibrous webs such as, but not limited to, woven webs Material may be included. Fine denier fibrous webs are particularly suitable for use herein, for example, meltblown webs containing nanofibers.
[0096]
The melt blowing process is suitable for making fine low denier fibers, especially low denier microfiber nonwoven webs. Suitable meltblown nonwoven webs preferably have fine diameters and include fine fibers that are dispersed as uniformly as possible in the web. Such nonwoven webs provide the desired combination of high liquid resistance and high air permeability.
[0097]
In one embodiment, the barrier region is about 4 to about 80 g / m ² , Preferably about 6 to about 70 g / m ² , More preferably about 8 g / m ² ~ About 50g / m ² , Most preferably about 10 to about 30 g / m ² A meltblown web of polypropylene fibers having a basis weight of.
[0098]
Meltblown fibers generally have an average diameter in the range of less than about 20 microns, preferably less than about 10 microns. Most commonly, meltblown fibers have an average fiber diameter in the range of 5 to 10 microns. Particularly suitable for use herein are nanofibers having an average fiber diameter in the range of less than about 500 nanometers, preferably less than about 300 nanometers, and more preferably less than about 150 nanometers. An exemplary nonwoven web made from nanofibers (having an average fiber diameter of about 10 to about 100 nanometers) is available from E-Spin Technologies (Chattanooga, TN). is there.
[0099]
Although the strength of a meltblown nonwoven web generally decreases with decreasing fiber fineness, its strength can be improved by laminating with a reinforcing scrim or other web such as a tissue, paper towel, or spunbond nonwoven web. Any conventional lamination method may be used, including adhesive bonding, heat bonding, ultrasonic bonding, calendering, needling, and combinations thereof. However, lamination methods need to be practiced well to minimize the deleterious effects of air permeability of the resulting laminate. In one embodiment, the microfiber nonwoven web may be laminated together during manufacture by meltblowing directly onto another web or reinforcing scrim.
[0100]
The fibrous barrier region may comprise a single web or multiple layers of webs having the desired properties collectively. However, when using multiple layers of web, the layers are not point bonded across the substantial surface area of their barrier area, or otherwise substantially limit the breathability of those areas. It is desirable that they be juxtaposed without being adhered in a proper manner. In one embodiment, the barrier region is not thermally point bonded or otherwise laminated to the absorbent core and / or storage region in a manner that disrupts the breathability of the article. In this regard, it may be desirable for the barrier region to be attached to other components, such as the absorbent article (absorbent core, storage region, etc.), primarily at the periphery of the barrier region. Many areas may be glued by heat, pressure, ultrasound, adhesive, or other means known in the art.
[0101]
The barrier region may contain additives such as chemical adhesives, crosslinkers, liquid or moisture absorbers, odor absorbers, antimicrobial agents, colorants, hardeners, and mixtures thereof. Liquid or moisture absorbers include clay, silica, talc, silicon earth, perlite, vermiculite, carbon, kaolin, mica, barium sulfate, aluminum sulfate, sodium carbonate, calcium carbonate, other carbonates, superabsorbent polymers, or Other permeable liquid retention agents, and mixtures thereof, include but are not limited to.
[0102]
(Components of absorbent articles)
FIG. 1 is a top plan view, partially cut away, of a diaper 20 including an absorbent barrier structure 10 of the present invention. The diaper 20 is in an unfolded state with a portion of the structure cut away to more clearly show the structure of the diaper 20. The clothing-facing surface of the diaper 20 is oriented away from the viewer.
[0103]
"Integral" absorbent article refers to absorbent articles formed from separate parts that are joined together to form a coordinated unity, which are separate operating parts, such as separate holders and / or liners. Do not need. As used herein, the term “diaper” refers to an absorbent article generally worn by infants and incontinent persons about the lower torso. "Integral" absorbent articles refer to absorbent articles formed from separate parts that are joined together to form a coordinated unity, which do not require separate operating parts. The term "disposable" is used herein to describe an absorbent article that is not generally intended to be laundered or otherwise intended to be reproduced or reused as an absorbent article (i.e., It is intended to be disposed of after a single use, preferably to be recycled, composted, or otherwise disposed of in an environmentally friendly manner.
[0104]
As shown in FIG. 1, the diaper 20 includes a liquid-permeable topsheet 24; a moisture management means 26; an absorbent core 28 disposed between at least a part of the topsheet 24 and the outer cover 22; An absorbent barrier structure disposed between the outer cover and the outer cover; a side panel; an elastic leg cuff; an elastic waist structure portion; The absorbent barrier structure 10 of the present invention is positioned proximate to the absorbent core 28 on the garment facing surface 45 of the absorbent core 28.
[0105]
The diaper 20, shown in FIG. 1, has a front waist region 36, a rear waist region 38 facing the front waist region 36, and a crotch region 37 located between the front and rear waist regions. The periphery of the diaper 20 has a longitudinal edge 50 running generally parallel to the longitudinal centerline 100 of the diaper 20 and a distal edge 52 having a longitudinal edge 50 generally parallel to the transverse centerline 110 of the diaper 20. Defined by the outer edge of the diaper 20 running there between.
[0106]
The body of the diaper 20 includes at least an absorbent core 28, a topsheet 24, and preferably, but not necessarily, a moisture management means 26. The outer cover 22 forms a chassis on which other components of the diaper 20 are added to form a unitary structure of the diaper.
[0107]
FIG. 1 shows an embodiment of a diaper 20 in which the topsheet 24 and the moisture management means 26 have generally greater length and dimensions than the absorbent core 28 and the absorbent barrier structure 10. The top sheet 24 and the moisture management means 26 may extend to the periphery of the diaper 20. In other embodiments, the absorbent barrier structure 10 may extend beyond the edge of the absorbent core 28 to the periphery of the diaper 20.
[0108]
While the components of the diaper 20 may be assembled in a variety of well-known configurations, a preferred diaper configuration is the "contractible side for disposable diapers," issued to Kenneth B. Buell on January 14, 1975. U.S. Pat. No. 3,860,003, entitled "Parts", U.S. Pat. No. 5,151,092, issued to Buell on Sep. 9, 1992, and Buell on Jun. 22, 1993. U.S. Pat. No. 5,221,274 to Roe et al., Issued Sep. 10, 1996, entitled "Absorbent with Multi-Segment Structurally Elastic-like Film Web Stretchable Waist Structure". U.S. Pat. No. 5,554,145 entitled "Articles", "Disposable Pull-On Pants" issued to Buell et al. On Oct. 29, 1996. U.S. Pat. No. 5,569,234 entitled "Zero Scrap Method for Manufacturing Side Panels for Absorbent Articles" issued to Nease et al. On December 3, 1996. U.S. Pat. No. 5,580,411 entitled "Absorptive Articles with Other Directionally Stretchable Side Panels" issued to Robles et al. On Dec. 21, 1999. No. 6,004,306, each of which is incorporated herein by reference.
[0109]
(Top sheet or body side liner)
The topsheet is compliant, soft to the touch, and non-irritating to the wearer's skin. The topsheet material is elastic and expandable in one or two directions. Further, the topsheet is fluid permeable, allowing fluids (eg, urine, menses, other body fluids) to easily pass through its thickness. Suitable topsheets can be made from a wide variety of materials, such as woven and nonwoven materials, perforated or hydraulically formed thermoplastic films, porous foams, reticulated foams, reticulated thermoplastic films and thermoplastic scrims. Suitable woven and nonwoven materials may include natural fibers such as wood or cotton fibers, synthetic fibers such as polyester, polypropylene, or polyethylene fibers, or combinations thereof.
[0110]
Preferred topsheets for use in the present invention are selected from bulky nonwoven topsheets and perforated film topsheets. Perforated film topsheets generally allow the excrement to pass through but do not absorb, reducing the tendency for fluids to return and re-wet the wearer's skin. Suitable perforated films are described in US Pat. No. 5,628,097, US Pat. No. 5,916,661, EP 1,051,958, EP 1,076,539. , Each of which is incorporated herein by reference.
[0111]
Nonwoven materials, such as those described in EP 774,242 (Palumbo), which is incorporated by reference and incorporated herein by reference, generally exhibit high gas permeability and, therefore, significant resistance to air flow. Not.
[0112]
Further, a suitable topsheet material for placing solid waste thereon may include a nonwoven fabric with holes, which is at least in a portion of the article aligned with the fecal attachment area. Suitable perforated nonwoven fabrics are described in more detail in EP 714,272 or EP 702,543, both of which are incorporated herein by reference. In other embodiments of the stool handling article, such topsheets can be combined with a stool handling member, for example, beneath such a topsheet, but are further described in these applications.
[0113]
The material forming the topsheet may be hydrophilic to facilitate fluid transport through the topsheet. As disclosed in European Patent Application No. 166,056 and U.S. Patent Application No. 07 / 794,745, filed November 19, 1991, surfactants are incorporated into polymeric materials to provide hydrophilicity to the topsheet. May be improved, both of which are incorporated by reference herein. Alternatively, the topsheet may be treated with a surfactant to render the body surface hydrophilic, as disclosed in U.S. Pat. No. 4,950,245, incorporated herein by reference.
[0114]
(Absorbent core)
The absorbent core comprises the following components: (a) optionally a first fluid distribution layer, (b) optionally a second fluid distribution layer, (c) a fluid storage layer, (d) a fibrous "dusting". And other optional components such as "layers".
[0115]
An optional first fluid distribution layer is generally located below the topsheet and is in fluid communication with the topsheet. The topsheet transfers the acquired body fluids to the first distribution layer and finally to the storage layer. This movement of the fluid through the first distribution layer occurs not only in the thickness but also along the length and width direction of the absorbent core. An optional second fluid distribution layer is generally located below and in fluid communication with the first fluid distribution layer. The second fluid distribution layer readily obtains fluid from the first distribution layer and rapidly transfers it to the underlying reservoir. Thus, the fluid capacity of the underlying reservoir may be fully utilized, especially when effluent eruptions occur.
[0116]
The fluid storage layer comprises an absorbent material, including an absorbent gelling material commonly referred to generally as a "hydrogel", "superabsorbent", "hydrocolloid" material. Absorbent gelling materials are materials that absorb such fluids upon contact with aqueous fluids, such as bodily fluids, to form a hydrogel. These absorbent gelling materials are generally capable of absorbing large amounts of aqueous bodily fluids and are capable of holding such absorbed fluids under moderate pressure. These absorbent gelling materials are generally in the form of discrete non-fibrous particles. Other shapes, such as fibers, foams, sheets, strips, or other giant structures are also suitable for use herein. Suitable absorbent gelling materials in the form of open cell foams are described in U.S. Pat. No. 3,563,243 (Lindquist), U.S. Pat. No. 4,554,297 (Dabi), U.S. Pat. No. 4,740,520 (Garvey) and US Pat. No. 5,260,345 (DesMarais et al.), All of which are incorporated herein by reference. Incorporate in the book. Improvements in these foams have been described in WO 96/21679, WO 96/21680, WO 96/21681, WO 96/21682, WO 97/07732, and Publication No. 98/00085, all of which are incorporated by reference herein.
[0117]
Absorbent gelling materials suitable for use herein may include substantially water-insoluble, slightly crosslinked, partially neutralized polymeric gelling materials. This material forms a hydrogel on contact with water. Suitable absorbent gelling materials are disclosed in US Pat. Nos. 4,654,039, 5,562,646, 5,599,335, and 5,669,894. And each of which is incorporated herein by reference.
[0118]
The superabsorbent material is preferably 30 * 10, as assessed by the disclosure of US Pat. No. 5,599,335, which is incorporated herein by reference. ^-7 cm ³ It has been found to be particularly suitable for use in the materials according to the invention if it exhibits a high saline flow conductivity (SFC) of more than s / g.
[0119]
Such materials can be placed in uniform mixing with the fluff pulp or, particularly when they are airlaid or nonwoven materials, a suitable open layer of porous material such as tissue and a permeable layer. Layers can be formed between them.
[0120]
A particularly suitable material is a superabsorbent / fluff mixture when placed in a uniform mixture with conventional fluff pulp at a superabsorbent concentration of 50% by weight, preferably 80% by weight, more preferably greater than 90% by weight. Superabsorbent materials as described in US Pat. No. 5,599,335 cited above. A suitable mixture is 0.1 g / cm ³ ~ 0.3cm ³ , Preferably 0.15 cm ³ ~ 0.2cm ³ May further be expressed.
[0121]
In certain embodiments, such mixtures can include means to increase the integrity of the mixture, especially in the dry state. Thus, small amounts of adhesives or other binders, such as synthetic fibers that can be heat bonded, may be added to the mixture.
[0122]
In addition to the liquid storage element of the core, the core may include other liquid handling members, such as to increase fluid acquisition or distribution.
[0123]
The fluid storage layer may include only the absorbent gelling material, or may be uniformly or non-uniformly dispersed on a suitable support, or may include only the absorbent support material. The reservoir may also include filler materials such as pearlite, diatomaceous earth, vermiculite, etc. that absorb and retain fluid and thus reduce rewet through the topsheet.
[0124]
Suitable support materials include cellulose fibers in the form of fluff, tissue, or paper. Modified cellulosic fibers (eg, cured, chemically treated, crosslinked) may also be used. Synthetic fibers may also be used. Suitable synthetic fibers include cellulose acetate, polyvinyl fluoride, polyvinylidene chloride, acrylics (such as Orlon®), polyvinyl acetate, water-insoluble polyvinyl alcohol, polyethylene, polypropylene, polyamides (nylon) (Registered trademark)), polyesters, bi- or tri-component fibers thereof, and mixtures of these materials. Preferably, the surface of the fibers is hydrophilic or has been treated to be hydrophilic.
[0125]
Generally, the storage layer comprises about 15-100% by weight of the absorbent gelling material dispersed in the support material. Preferably, the storage layer comprises from about 30 to about 95%, more preferably from about 60 to about 90%, by weight of the absorbent gelling material. The support material generally comprises about 0 to about 85%, preferably about 5 to about 70%, more preferably about 10 to about 40% by weight of the storage layer.
[0126]
An optional component for inclusion in the absorbent core is a fibrous layer located adjacent to and generally below the storage layer. The underlying fibrous layer is commonly referred to as a "dusting" layer, which is a substrate for placing the absorbent gelling material in the storage layer during the manufacture of the absorbent core. In order to provide. Further, the "dusting" layer provides some additional fluid handling capabilities, such as allowing fluid to escape quickly along the length of the absorbent core.
[0127]
The absorbent core may include any other components. For example, a reinforcing scrim may be located within each region of the absorbent core, or may be located between each region. Optionally, an odor control agent may be included in the absorbent core. Suitable odor control agents include activated carbon, zeolites, clays, silicas, and mixtures thereof. The shape and composition of the absorbent core may vary (eg, the absorbent core may have various caliber zones, hydrophilic agents, pore size gradients, superabsorbent gradients, or lower average densities, and lower average basis weight gain areas). Or may include one or more regions or structures.) However, the overall absorbent capacity of the absorbent core must be compatible with the design load and the intended use of the diaper. Further, the dimensions and absorbent capacity of the absorbent core may be varied to accommodate wearers ranging from infants to adults. Suitable absorbent cores include those disclosed in EP 1,051,958, EP 797,968, and EP 774,242, each of which is incorporated herein by reference. Incorporate in the book.
[0128]
(Outer cover)
As used herein, the term "outer cover" means a structural element located on the garment-facing surface of the absorbent article. The outer cover generally forms a chassis on which other components of the diaper are added. However, the outer cover may simply be a coating layer on the garment side of the absorbent article.
[0129]
Suitable materials for the outer cover must allow air or vapor to flow (ie, vapor permeable) but provide a barrier function for liquids (ie, liquid impermeable). The outer cover must not be a rate limiting element for the transport of gas or vapor through the absorbent article. Preferably, the outer cover is relatively open and has a structure that allows convective air or gas permeability. Suitable outer covers generally have at least about 500 g / 24 hours / m ² , More preferably at least about 1500 g / 24 hours / m ² , Most preferably at least about 3000 g / 24 hours / m ² With a vapor transmission rate (MVTR) of In addition, the outer cover provides soft comfort to the skin, either by material properties or by texturing, embossing, or both on the surface.
[0130]
The outer cover may be a single layer of uniform or multiple component materials, or may be a composite of multiple layers of multiple materials. Outer covers suitable for use herein include perforated films (eg, having a plurality of shaped openings or folded capillaries), knitted webs, porous woven or nonwoven webs, foams, or these. Or a porous material such as a laminate. In one embodiment, the outer cover comprises a nonwoven web or a multi-layer nonwoven such as a spunbond / meltblown (SB) nonwoven, a spunbond / meltblown / spunbond (SBS) nonwoven.
[0131]
The outer cover or any portion thereof may be elastically extensible in one or more directions. In one embodiment, the outer cover may include a structural elastic-like film (SELF) web. SELF webs are extensible materials that exhibit an elastic-like behavior in the direction of elongation without the use of additional elastic materials, and are referred to as “Elastic-like webs” issued to Chappell et al. On May 21, 1996. It is described in more detail in U.S. Patent No. 5,518,801, entitled "Material", which is incorporated herein by reference. In alternative embodiments, the outer cover may combine an elastomeric component (eg, film, foam, strand, or a combination thereof) with a nonwoven or synthetic film.
[0132]
In other embodiments, the outer cover may be a nonwoven web configured to provide the required level of liquid impermeability. For example, a nonwoven web of spunbond or meltblown polymer fibers may be at least partially treated with a hydrophobic coating. Representative examples of the use of fluorocarbons are U.S. Patent No. 5,876,753, issued March 2, 1999 to Timmons et al., And Gleason et al., Issued March 30, 1999. U.S. Pat. No. 5,888,591 issued to Gleason et al. On Apr. 4, 2000, and U.S. Pat. No. 6,045,877 issued to Gleason et al. No. 99/20504, filed by 'Agostino) et al., Which are incorporated herein by reference.
[0133]
Optionally, the outer cover material is an absorbent and swellable material as described in US Pat. No. 5,955,187, issued to McCormack et al. Absorbable and contractile materials described in U.S. Patent Application No. 97/22604, filed by Corzani et al. On March 15, or in WO 00/68003 by Dawson et al. Absorbent and specific strainable materials may be included and these specifications are incorporated herein by reference.
[0134]
The absorbent article may include an outer cover that is at least partially separated from the absorbent core by the absorbent barrier structure of the present invention, or by an attachment means such as those well known in the art. And / or preferably joined to the absorbent core. As used herein, the term “joined” refers to a configuration in which one element is directly secured to another element by directly securing one element to another element, and one element is secured to an intermediate member; Include features in which one element is indirectly secured to another element by then securing the member to the other element.
[0135]
The outer cover is disclosed in U.S. Pat. No. 4,573,986, issued Mar. 4, 1986 to Minetola et al., And U.S. Pat. No. 3,911,173; U.S. Pat. No. 4,785,996 to Ziecker et al. On Nov. 22, 1978; and to Werenics on Jun. 27, 1989. As disclosed in U.S. Pat. No. 4,842,666, incorporated herein by reference, a single continuous layer of adhesive, an open mesh of adhesive filaments, or an array of discrete lines, spirals or dots of adhesive can be used to absorb. May be affixed to the permeable barrier structure and / or the absorbent core, each of which is incorporated herein by reference. Adhesives whose utility has been recognized are described in B. Manufactured by HB Fuller Company (St. Paul, Minn.) And sold as HL-1258. Alternatively, the attachment means may include a thermal bond, a pressure bond, an ultrasonic bond, a dynamic mechanical bond, or any other suitable adhesive means known in the art or a combination of these attachment means.
[0136]
The outer cover material should not significantly reduce the convective air permeability of the absorbent article. More importantly, depending on the combination of the absorbent barrier structure and the outer cover (hereinafter referred to as "combined structure" or "combination"), including but not limited to absorbent, barrier properties, and convective air permeability A desired balance of properties not provided is provided.
[0137]
The combined structures of the present invention are assembled to form at least about 10 Darcy / mm, preferably at least about 20 Darcy / mm, more preferably at least about 30 Darcy / mm, and most preferably at least about 50 Darcy / mm. mm of convective air permeability. Convective air permeability is particularly effective in removing vapors from the interior of the absorbent article, lowering the humidity of the local environment in the immediate vicinity of the skin, which reduces the occurrence of skin irritation and reduces skin irritation. Promotes health.
[0138]
Further, the combined structures of the present invention preferably have a weight of about 10 g / m2. ² Or less, more preferably about 8 g / m ² Or less, most preferably about 5 g / m ² It has the following dynamic liquid impact value (as measured by Test Method C):
[0139]
Further, the combined structure should exhibit a head value of at least about 20 mbar, preferably at least 35 mbar, more preferably at least about 50 mbar, and most preferably at least about 75 mbar.
[0140]
In a preferred embodiment, the combined structure of the present invention exhibits the desired leak protection or barrier properties at least equal to that of an absorbent barrier structure.
[0141]
(Moisture management means)
Optionally, as shown in FIG. 3, a moisture management means 26 may be included in the absorbent article of the present invention. The moisture management means 26 may provide additional leak protection. Suitable moisture management means materials are breathable materials that allow steam to escape from the diaper 20 while preventing emissions from passing through the moisture management means 26. Exemplary materials may include composite materials such as perforated films, preferably perforated monolithic or microporous films, modified (with respect to pore structure and distribution) nonwovens or film / nonwoven laminates. .
[0142]
Suitable perforated films generally have an open surface area of at least about 1%, preferably at least about 5%, more preferably at least about 10%. In other embodiments, the open surface area may be 0.1% or more if a sufficient amount of relatively large pores are present. In addition, suitable perforated films must have an open surface area of less than 20%, thereby having a substantial effect on the leak protection properties of the article. The perforated film may be formed in a vacuum or may be hydroformed to provide macropores and / or micropores. A more detailed description of suitable perforated films is given in U.S. Patent Nos. 4,629,643, 4,609,518, 4,695,422, and 4,342,314. And U.S. Pat. No. 4,463,045, each of which is incorporated herein by reference.
[0143]
In other embodiments, the moisture management means may include different breathable and / or liquid permeable regions. For example, the moisture management means may be more breathable and / or liquid permeable in areas that do not coincide with the absorbent core. The term "breathable" as used herein refers to the diffusive transport of water vapor through a material. The moisture management means may be assembled from one or more layers and preferably includes at least one layer that is liquid impermeable, the liquid impermeable layer preferably being located proximate to the absorbent core, An area at least as large as the core is preferably covered.
[0144]
In addition, the condensation of moisture on the exterior surface of the absorbent article (i.e., the garment side) induces moisture on contact, which reduces wearer comfort and is often perceived as a performance issue of the article. Convective transport of vapor through the absorbent articles of the present invention is very effective and can result in condensation of moisture on the outer surfaces of the articles and perceived moisture problems.
[0145]
Therefore, it may be beneficial to incorporate relatively low permeability moisture management means into the articles of the present invention. A suitable low-permeability moisture management measure is about 4500 g / m ² / 24 hours or less, preferably about 3500 g / m ² / 24 hours or less, more preferably about 3000 g / m ² / 24 hours or less, most preferably about 2500 g / m ² Must have a MVTR of / 24 hours or less.
[0146]
The moisture management means may be located between the outer cover and the absorbent barrier structure of the present invention. Alternatively, the moisture management means may be located within the absorbent barrier structure between one or both of the absorbent and barrier layers.
[0147]
(Other components)
In addition, the diaper may further include a pair of fasteners 40 used to secure the diaper around the wearer's waist, as shown in FIG. Suitable fasteners include hook and loop fasteners, adhesive tape fasteners, buttons, snaps, mushroom and loop fasteners, and the like. The diaper of the present invention may also include an elasticized leg band to help secure the diaper to the wearer, to help reduce leakage from the diaper. Similarly, a pair of elasticized longitudinal extensions formed to maintain a substantially upright vertical configuration along the central portion of the diaper and act as an additional barrier to lateral flow of waste. It is also known to provide a confining flap that does.
[0148]
It is also common to include a surge management layer disposed between the topsheet and the absorbent core to help prevent fluid pooling on portions of the diaper close to the wearer's skin.
[0149]
The articles of the present invention receive pockets for receiving and containing excrement, spacers providing voids for excrement, barriers for restricting the movement of excrement in the article, and receiving excrement deposited on the diaper 20. It may also include a waste management mechanism portion, such as a containment compartment or void, and combinations thereof.
[0150]
Optionally, the absorbent article of the present invention may comprise a skin care composition, preferably on the skin-contacting surface of the article. The skin care compositions useful herein maintain and / or improve the skin under an absorbent article, or the skin condition of the skin, which is routinely or rapidly exposed to bodily discharges, moisture, irritants, etc. Turned to The skin care composition provides a protective and preferably non-occlusive function (eg, a barrier that is relatively liquid impermeable but vapor permeable), resulting in skin hyperhydration and body discharge (eg, : It is preferable to avoid exposing the skin to substances contained in urine, feces, menstrual fluids). It is also preferred that the skin care composition provides a light minimizing function and reduces skin irritation in areas where the absorbent article contacts the wearer's skin. Further, the skin care composition may contain skin care ingredients that reduce hyperhydration, reduce redness, humidify the skin, and remove or reduce skin irritants in body discharge. Provide the benefits of such skin care, directly or indirectly. The skin care composition also preferably contains an emollient that protects or improves the skin from rough, rough, wrinkled appearance or itching. Skin care compositions may contain skin soothing agents such as aloe vera, chamomile.
[0151]
Skin care compositions suitable for use in the present invention are described in co-pending US patent applications Ser. Nos. 08 / 926,532 and 08 / 926,533, filed Sep. 10, 1997, 1998, respectively. U.S. Patent Application Nos. 09 / 041,509, 09 / 041,232, 09 / 041,266, each filed on March 12, and U.S. Patent Application No. 09, filed May 2, 2000 U.S. Patent No. 5,607,760, filed March 4, 1997; U.S. Patent Application Serial No. 09 / 466,343, filed December 17, 1999, March 1997; U.S. Pat. No. 5,609,587 issued on Jun. 11, 1997; U.S. Pat. No. 5,635,191 issued Jun. 3, 1997; U.S. Pat. 5,643,588 It has been described in US Pat. No. 6,153,209, issued on November 28, 2000, cited these herein by reference incorporated herein.
[0152]
(Preparation of absorbent barrier structure)
In one embodiment, the nonwoven web and the cellulosic web forming the absorbent barrier structure are adhesively bonded using an Ato-Findley adhesive H2031F. The nonwoven web is unwound from the supply rolls and advances to a spray station where the adhesive is preheated to its molten state and sprayed onto the web substrate (using a Dynatec® spray head), and then the nonwoven The web is combined with the cellulosic web to form an absorbent barrier structure. The adhesive forms three continuous strips along the length of the advancing web.
[0153]
The strips are substantially parallel. Each strip is 22 mm wide and the outer strip is about 4 mm from the periphery of the web.
[0154]
In another embodiment, the first nonwoven web and the cellulosic web may be adhesively bonded by the method described above. The second nonwoven web is unwound from a supply roll, spray coated with an adhesive, and then bonded to the free surface of the cellulosic web. In another three-layer absorbent barrier structure, two nonwoven webs are unwound from separate supply rolls, spray coated with an adhesive, and then simultaneously bonded to opposing surfaces of the cellulosic web.
[0155]
The absorbent barrier structure may be incorporated into a disposable diaper having a general structure, such as the diaper shown in FIG. 1, according to well-known assembly processes. Generally, the absorbent barrier structure is located between the absorbent core and the outer cover. In a two-layer construction, the barrier layer is located proximate the garment facing side of the absorbent core and the absorbent layer is located proximate the outer cover. In a three-layer construction, the first barrier layer is located proximate the garment-facing side of the absorbent core and the second barrier layer is located proximate the outer cover. Other known components may be incorporated into the diaper without departing from the spirit of the present invention. In addition, techniques and methods of using these known components related to the absorbent articles of the present invention will be similarly readily appreciated by those skilled in the art.
[0156]
(Test method)
A. Air permeability
Air permeability is determined by measuring the time required for a standard amount of air to pass through a sample at a constant pressure and temperature. This test is particularly suitable for materials having relatively high permeability to gases, such as nonwovens, perforated films, and the like.
[0157]
The instrument uses a TexTest FX3300. The test method complies with ASTM D737. The test is generally performed in an experimental environment at about 22 ± 2 ° C. and a relative humidity of about 35% ± 15%. The sample must be conditioned for at least about 2 hours. Test pressure is 125 Pascal, test area is 38cm ² It is. In this test, the instrument creates a constant and different pressure across the sample, which draws air into the sample. The speed of the air flow to the sample is in feet ³ / Min / ft ² And converted to performance (in Darcy / mm) according to Darcy's law.
[0158]
K / d (Darcy / mm) = (V _* μ) / (t _* A _* Δp)
Where k is the permeability per unit area of the sample and V / t is cm ³ Is the volumetric flow rate in μs / sec, μ is the viscosity of air (1.86 _* 10 ^-5 Pa)), d is the thickness of the test substance in mm, and A is cm ² Is the cross-sectional area of the sample at and Δp is the pressure difference in Pascal or Pa, 1 Darcy = 9.869 _* 10 ^-9 cm ² It is.
[0159]
Repeat three times for each sample and record the averaged result.
[0160]
B. Hydrostatic head (water head) pressure test
The property determined by this test is a measure of the material's liquid barrier properties (or liquid impermeability). In particular, this test measures the hydrostatic pressure that the material supports when a controlled level of water permeation occurs.
[0161]
A rising water column tester, TexTest hydrostatic head tester FX3000 (available from Advanced Testing Instruments, Corp., Spartanburg, South Carolina) is used. The test method is in accordance with Edana 120.1-18. For this test, pressure is applied to a defined sample portion and gradually increases until water passes through the sample.
[0162]
The test is typically performed in an experimental environment at about 73 ° F. ± 2.0 ° F. (22.8 ° C. ± 0.6 ° C.) and a relative humidity of about 50 ± 2%. The sample is clamped on top of the column fixture with a suitable gasket material (O-ring type) to prevent side leakage during testing. When an absorbent barrier structure having a layer of barrier material and a layer of storage material is the sample being tested, the sample will have the layer of barrier material facing the water column during the test. The area of water in contact with the sample is equal to the cross-sectional area of the water column, which is 28 cm ² be equivalent to.
[0163]
Water is injected into the water column at a rate of 3 mbar / min. Thus, the sample is subjected to a steadily increasing water pressure on one surface. As water permeates at three points on the other surface of the sample, the pressure at which the third permeation occurs is recorded. If water passes through the sample immediately (ie, when the sample does not show resistance), a zero is recorded. Three samples are tested for each substance and the results are averaged.
[0164]
C. Dynamic liquid impact test
The properties determined by this method are related to the ability to withstand fluid resistance under sudden impact and relate to the leak protection provided by the absorbent structure of the present invention. In this test, a sample of the absorbent structure is placed in close proximity to a filled absorbent core analog, and the combination is subjected to an impact. The properties determined by this method are related to the actual use conditions in which the impact force is applied to the filled diaper from the standing position of the wearer (particularly the baby).
[0165]
The dynamic liquid impact test is measured with the device 9100 shown in FIG. According to this test, the absorbent core analog 9104 is placed directly on top of the energy absorbing impact pad 9103. Absorbent core analogs are available from VWR Scientific (Cleveland, Ohio) and are available from Whatman Laboratory Division, No. 1; 4 Includes four layers of filter paper. The absorbent core analog is filled with 2 grams of pseudo urine. Simulated urine is a 0.9% by weight saline solution and represents a surface energy value as conventionally determined to be 72.5 mN / m.
[0166]
The energy absorbing impact pad 9103 is a carbon black filled crosslinked rubber foam. The impact pad 9103 measures 12.7 cm x 12.7 cm (5 in x 5 in) and has a 0.1132 g / cm ³ And a thickness of 0.3125 inches. The impact pad 9103 has a durometer value of A / 30/15 according to ASTM 2240-91.
[0167]
The absorbent structure sample 9105 of the present invention includes a barrier region and a storage region arranged in a layered relationship, disposed over the absorbent core analog 9104, with the barrier layer facing down (ie, the barrier layer). Is located directly on the absorbent core analog). The sample / core analog assembly is located in the center of pad 9103.
[0168]
An absorbent material 9102 weighing approximately 0.0001 grams is placed on top of the sample 9105 to be tested. Absorbent material 9102 is available from Whatman Laboratory Division under No. Includes 4 filter papers. The absorbent material 9102 needs to be able to absorb and retain the pseudo urine which passes through the test sample 9105. The absorbent core analog 9104 and the sample 9105 need to have an area slightly larger than the impact area of the surface 9110.
[0169]
The impact arm 9108 is raised to a desired impact angle (about 30 °) to provide a desired impact energy. The impact arm 9108 is lowered and rests on the sample for 2 minutes after impact. The arm is then raised and the filter paper is removed and placed on the digital scale. The weight of the wet filter paper is then recorded in three minute code. The liquid shock transfer (LIT) value is calculated and g / m using the following equation: ² Represented by:
LIT = [weight of wet filter paper (gram) −weight of dry filter paper (gram)] / [impact area (m ² )]
m ² Is the area of the absorbent core analog 9104. The impact area is 0.003848m ² It is. Test three samples for each material and record the average result.
[0170]
D. Static liquid transfer test
The properties determined by this test relate to the fluid retention capacity (or leak protection) provided by the absorbent barrier structure of the present invention under shock and sustained pressure conditions. The properties determined by this test relate to the actual use of the wearer, who suddenly moves from a standing position to a second position (eg, sitting) and maintains the second position for an extended period of time.
[0171]
The equipment and sample equipment are the same as those of the dynamic liquid impact test described above, except that in this test the impact arm 9108 is lowered and rests on the sample for a controlled time after impact. The arm 9108 is then raised, the filter paper 9102 is removed and weighed, and the change in weight is recorded as described above. The holding times at rest are 2, 5, 8, 15, 30, and 60 minutes.
[0172]
E. FIG. Steam permeation rate
The vapor transmission rate (MVTR) determines the amount of moisture absorbed by calcium chloride in a "cup" -like container, which is covered by the test sample, where the moisture source is separated from the calcium chloride by the test sample Controlled temperature / humidity environment (40 ± 3 ° C./75±3% relative humidity). This method is applicable to thin films, multilayer laminates, and the like.
[0173]
The sample holding the cup is a cylinder with an inner diameter of 30 mm and a height of 49 mm inside from the bottom to the upper flange. A flange having a circular opening and mating with the cylinder opening can be screwed in, and a silicone rubber sealing ring with an opening matching the inner diameter of the cup fits between the upper flange and the cylinder. The test sample is placed so as to cover the cylinder opening. The sample is neatly fixed between the silicone rubber seal and the top flange of the cylinder, acting as a barrier to moisture transport.
[0174]
The equipment and samples need to be stable at the temperature of the controlled environment before testing.
[0175]
The absorbent desiccant is CaCl 2 as available from Wako Pure Chemical Industries Ltd. (Richmond, Virginia) under the product name 030-00525. ₂ It is. If in a sealed bottle, it can be used directly. If lumps or excessive amounts of fines are present, they can also be sieved out. It may be dried at 200 ° C. for about 4 hours.
[0176]
CaCl ₂ Is weighed (15.0 ± 0.02 g) into a glass and tapped lightly to level the surface, so that the surface is about 1 cm from the top of the glass.
[0177]
The sample is cut to about 3.2 cm x 6.25 cm, laid flat, overlapped with a seal over the opening, and the seal and top flange secured so as not to be too tight with screws. The total weight of the cup assembly is accurately recorded to four decimal places, and the assembly is placed in a constant temperature / humidity room.
[0178]
After 5 hours of exposure to the test humidity (without opening the room), the sample is removed and immediately covered tightly with a non-vapor permeable plastic film such as Saran wrap. After settling for about 30 minutes for temperature stabilization, the plastic film is removed and the mass is reweighed.
[0179]
Thereafter, the increase in humidity over 5 hours by passing through a 3 cm circular opening was determined and the result was reported as "g / m ² The MVTR value is calculated by converting to "/ 24 hours" units. Repeat three times for each sample, average the values obtained, and round the result to a value of approximately 100.
[0180]
F. Air permeability after compression
When a material, particularly one having a relatively flexible or open structure, is subjected to compressive or sustained pressure, the material may undergo structural changes. After the applied force is removed, the material may not return completely to its original state. This residual structural change often results in changes in properties such as air permeability. This test method is a measurement of the elasticity of a sample material after being subjected to a predetermined time of compression or continuous pressure.
[0181]
The absorbent barrier structure of the present invention is incorporated into an absorbent article such as a diaper, which is often packaged in a highly compressed state and stored for such a long time. In addition, while the absorbent article is being worn, the wearer exerts a sudden impact on the article (eg, the wearer suddenly moves from a standing position to a sitting position) and then continues pressure (eg, (To maintain a sitting posture). Certain articles or structures are susceptible to change under such conditions and do not recover to their initial condition after compression or pressure is removed. Thus, the material or structure may have high air permeability when made, but perform such performance after being compressed and stored in the package or when subjected to the continuous pressure applied by the wearer. There are things you can't do.
[0182]
The sample sheet or laminate is cut into dimensions of 40 mm x 165 mm. The sample sheets are stacked and placed between two plexiglass plates. Pressure is applied over the glass plate, reducing the overall thickness of the stack of sample sheets to a controlled value. The level of compression is calculated by the following equation:
[0183]
(Equation 1)

Where H is the overall thickness after pressure is applied to compress the sample stack;
d is the initial thickness of the sample stack;
n is the number of layers in the sample sheet,
k is the compression level.
[0184]
The stack of compressed samples is placed in a climate controlled room at 60 ° C. and 50% relative humidity for a predetermined time. Generally, testing is performed on five sample sheets or laminates, each stacked and compressed 50%. The test may be applied to any number of layers of the sample sheet or at different compression levels.
[0185]
The air permeability of the sample is determined before compression and after 24 hours of compression. The air permeability after compression is measured after a waiting time, which allows the sample to recover (taking into account that the sample may not exhibit permanent deformation and does not recover to its initial pre-compression state). It is enough time. In this test, air permeability is determined by measuring the time that a standard quantity of air passes through a test sample at a constant pressure and temperature.
[0186]
The test is performed in an environment where the temperature and humidity are controlled at 22 ± 2 ° C. and 35% ± 15% relative humidity. The test sample must be conditioned for at least 2 hours.
[0187]
Test devices such as those manufactured by Hoppe & Schneider GmbH (Heidelberg, Germany) under the name of "Textilur nach Kretschmar" are essentially arranged vertically. A bellow, the upper end of which is mounted in a fixed position, the lower end of which is releasably held in its upper position, which is loosened by an opening handle and slips to a lower position in a controlled manner; This increases the volume inside the bellows by drawing air into the test sample covering the air entry opening at the upper end of the bellows. Test sample is firmly held and 5cm ² Or 10cm ² The cover ring covers the air opening and allows for different sample sizes and / or different permeability ranges. 10cm ² If a ring is used, the sample is at least 55 mm wide and 5 cm ² The ring needs to be at least 35 mm in width. For both, the sample must have a length of about 150 mm.
[0188]
For very high permeability materials, the aperture can be further reduced with appropriate adjustments to the equipment and calculations.
[0189]
The device is equipped with a stopwatch (1/100 second) and automatically measures the time when the opening handle operates to initiate bellows sliding and the time when the lower part of the bellows reaches the lower end position.
[0190]
The air permeability k of the material is calculated according to the Darcy's law described above, where different parameters are used (due to differences in equipment mechanics). Especially for the test equipment used here, V is 1900 cm ³ And A is 4.155 cm ² And p is 160 Pa.
[0191]
The test must be performed once for each test sample (either a single material or a sheet made from a laminate of different materials) and repeated for five samples. Record the average of at least three useful tests for each sample material or laminate.
[0192]
The average value is recorded in Darcy / mm, taking into account the unit thickness of the material.
[0193]
G. FIG. Absorption test
This test measures the absorbency of a high suction capillary of absorbent material. Capillary sorption is a fundamental property of any absorbent that governs how fluid is absorbed into the absorbent structure. High suction capillary sorption is characterized by the ability of the substance to separate fluid from competing materials.
[0194]
The porous glass frit is connected to the fluid reservoir via a fluid unobstructed cylinder, the fluid level of which is flush with the horizontal center of the porous frit structure. The sample absorbs the required fluid and records its steady state weight. Fixed height absorption experiments thus provide information on liquid wicking (g / g) in the horizontal direction.
[0195]
(Experiment preparation)
The test liquid used herein was 0.2 wt% Triton® X-100 (Sigma-Aldrich Inc.) with a surface tension of about 33 dynes / cm. (Available) aqueous solution. This test method is adapted to use water or other test liquids such as synthetic urine (with a surface tension of about 75 dynes / cm and about 55 dynes / cm).
[0196]
A porous glass frit funnel is filled with the test liquid. This frit funnel (available from VWR Scientific Products (Cleveland, Ohio)) has a volume of 350 ml and a hole of 10-15 microns, the bottom outlet of which is modified by a glass blower. With tubing capacity. A 1.40 m long Tygon tube (part no. R3603, available from VWR Scientific Products) is attached to the bottom of the funnel and filled with test liquid. The frit funnel is clamped to the stand. The Tygon tube end is attached to the frit funnel at the end of the tube several centimeters above the frit disc.
[0197]
The funnel is filled with 100 ml of the test liquid (the raised tube ends prevent the liquid from flowing out of the frit) and are covered with plastic wrap. The frit is then stored for 5 to 12 hours, allowing any air trapped in the frit holes to escape. Any observable air bubbles need to be removed from the frit or tube. Tygon tubing is placed in a glass fluid reservoir (20-25 cm in diameter) filled with test fluid. The fluid level in the center of the frit and in the reservoir area is set at the same height. Use a level to ensure that the frit surface is level.
[0198]
Between experiments, the frit funnel is covered with plastic wrap to prevent evaporation and drying of the test liquid from the frit holes, but the frit funnel is not covered during the experiment.
[0199]
If the frit is not used for several hours, it must be stored as follows: The Tygon tubing is removed from the fluid reservoir and attached to a fritted funnel at the end of the tubing, rising several centimeters above the frit disc. The funnel is filled with 100 ml of test liquid (the raised tube ends prevent the liquid from flowing out of the frit) and covered with plastic wrap.
[0200]
(Experimental procedure)
Ensure that no observable air bubbles are trapped under the frit or in the tube. A 5.40 cm diameter sample is cut using an arch punch. Weigh the sample. Separate the clamp below the frit funnel. The sample is spread evenly over the central area of the frit surface. Place an annular weight on the sample. Remove the clamp and allow the sample to absorb for 2.5 minutes. Remove the annular weight and then remove the sample from the frit. If the frit funnel needs to be lowered or tilted further to remove the sample, the frit funnel tube below the frit funnel must be unclamped before removing the sample from the frit (additional fluid may be removed during removal). To ensure that it is not absorbed by the sample). Weigh the sample. Repeat the procedure with the next sample. Repeat twice for each sample and record the net and average net siphoning obtained for each frit. Record which frit was used (flit # or other identification number). If the results of the two tests differ by more than 10% (based on higher values), check the frit and sample preparation and repeat the experiment. Calculate the absorbency (or wicking) of the liquid according to the sample as follows:
[0201]
Net siphoning g / g = (sample wet weight g−sample dry weight g) / sample dry weight g (practical example)
(Example 1)
In this example, the absorptive barrier structure of the present invention is a two-layer laminate that includes an absorbing region and a barrier region substantially overlying the barrier region. FIG. 2A schematically illustrates this embodiment, where the absorbent barrier structure 10 includes a barrier layer 12 and an absorbent layer 14. The absorbent layer is a cellulose fiber web of natural fibers commercially available as Bounty® paper towels (manufactured by Procter and Gamble Company (Cincinnati, Ohio)). is there. The web has a double structure. The total weight is about 43 gsm and the total thickness is about 0.686 mm. The barrier layer is a polypropylene spunbond / meltblown nonwoven web (manufactured by BBA Nonwovens (Simpsonville, SC) under the name MD2005) with a basis weight of about 27 gsm and a thickness of about 0 gsm. .305 mm.
[0202]
(Example 2)
In this example, the absorbent barrier structure has a three-layer structure and includes first and second barrier regions disposed on opposite sides of the absorbent region. FIG. 2B schematically illustrates this embodiment, wherein the absorbent barrier structure 10 includes two barrier layers 12 and 16 and an absorbent layer 14 between the two barrier layers. The absorbent layer is a double Bounty® paper towel. The first and second barrier layers are a meltblown (MB) polypropylene nonwoven web (manufactured under the name PP-015-FN by Gentex Corporation (Buford, Georgia)). is there. The MB nonwoven webs each have a basis weight of about 15 gsm.
[0203]
(Example 3)
In this example, the first barrier layer is an MB polypropylene nonwoven web from Jentex having a basis weight of about 10 gsm, and the second barrier layer is made from microdenier fibers having a basis weight of about 17 gsm. Absorbent barrier, except spunbond / spunbond polypropylene nonwoven web (available from FirstQuality Fibers Nonwovens (Hazelton, PA) under the name GCAS160021184) The structure has substantially the same structure as described in Example 2.
[0204]
(Example 4)
In this example, the first barrier layer is a MB nonwoven web from Jentex, having a basis weight of about 5 gsm, and the second barrier layer is a MB non-woven web from Jentex, having a basis weight of about 10 gsm. Except that it is a MB nonwoven web, the absorbent barrier structure has substantially the same structure as described in Example 2.
[0205]
(Example 5)
In this example, the first barrier layer is a MB non-woven web from Jentex, having a basis weight of about 10 gsm, and the second barrier layer is a MB non-woven web from Jentex, having a basis weight of about 5 gsm. Except that it is an MB nonwoven web, the absorbent barrier structure has substantially the same structure as described in Example 3.
[0206]
(Example 2b)
In this example, the absorbent barrier structure has substantially the same structure as described in Example 2, except that the absorbent layer is a single layer BOUNTY®.
[0207]
(Example 3b)
In this example, the absorbing barrier structure has the same structure as described in Example 3, except that the absorbing layer is a single layer bounty (BOUNTY).
[0208]
(Example 2c)
In this example, the absorbent barrier structure is substantially the same as described in Example 2, except that the absorbent layer comprises two superimposed layers of BOUNTY® With structure.
[0209]
(Comparative example)
Comparative Example 1 is a BOUNTY® towel available from Procter & Gamble Company (Cincinnati, Ohio).
[0210]
Comparative Example 2 is a molded film with folded capillaries on the surface as described in EP 934,735 and EP 934,736. Molded films are made from polyethylene and are available from Tredegar Film Products Corporation (Terre Haute, IN).
[0211]
Comparative Example 3 is a microporous film. This film is made from polyethylene with 40-45% by weight calcium carbonate filler. This film is available from Clopay Plastic Products Company (Cincinnati, Ohio).
[0212]
Comparative Example 4 is a polypropylene SS nonwoven web available from First Quality Fibers Nonwovens (Hazelton, Pa.) Under the name GCAS160021184.
[0213]
Comparative Example 5 is a polypropylene MB nonwoven web available under the name PP-015-FN from Jentex Corporation (Buford, Georgia).
[0214]
Example 6
The properties of the above examples are tested according to the test methods disclosed herein. For a three-layer construction, the first barrier layer is placed close to the absorbent core during testing. The test results are summarized in Tables 1a and 1b.
[0215]
[Table 1]

[Table 2]

The test results in Table 1a show that the present invention provides a unique structure with the desired balance of properties.
[0216]
The test results in Table 1b show that the comparative examples do not provide the desired balance of properties. BOUNTY® paper towels (Comparative Example 1) have excellent air permeability but poor liquid impermeability. The microporous film (Comparative Example 2) has excellent liquid impermeability but is substantially air impermeable. The nonwoven webs (Comparative Examples 3-5) are air permeable and liquid impermeable in general conditions. However, the nonwoven web becomes liquid permeable under impact and / or pressure conditions.
[0219]
(Example 7)
In this example, a three-layer absorbent barrier structure as described in Example 2 is combined with an outer cover material, which is a polypropylene having a 16 gsm SB layer and a 11.5 gsm MB layer. 2 is a SM nonwoven web. The combination structures are tested according to the test methods described herein. The test results are summarized in Table 2.
[0218]
[Table 3]

When compared to the absorbent barrier structure of Example 2, the combined structure is more liquid impermeable and more resistant to wet passage under impact, but has lower air permeability. Overall, the combined structure also provides the desired balance of properties.
[0219]
(Example 8)
In this example, the absorbent barrier structure of Example 2 is combined with the outer cover material according to Example 7. Further, a perforated film is disposed between the second barrier layer of Example 2 and the outer cover of Example 7. The perforated film is made of polyethylene with 11.7% open area. The holes are hexagonally shaped openings. The perforated film used herein is manufactured by BP Chemicals (Wasserburg, Germany) under the trade name (HEX-B type 45109). Perforated film manufactured under the name HEX-B by Tredegar Film Products Corporation (Terre Haute, IN) is also suitable for use herein.
[0220]
The overall structure, including the absorbent barrier structure, the perforated film, and the outer cover, was tested according to the test methods described herein and compared to Example 7 without the perforated film. The results are summarized in Table 3 below.
[0221]
[Table 4]

The open structure of the perforated film does not substantially affect the overall convective air permeability. Perforated films reduce the liquid impermeability of the entire structure, especially under impact conditions. The results show that the entire structure, including the addition of the apertured film, achieves the desired balance of properties. More importantly, the perforated film reduces diffusive MVTR throughout the structure. Thus, the unique combination of permeability provides a structure that desirably exhibits reduced moisture or condensation on the exterior surface of the structure.
[0222]
(Example 9)
In this example, the absorbent layer is a cellulose web (i.e., BOUNTY (R) towel) surface treated on both sides with a hydrophobic agent. The surface treatment method is described in WO 00/14296 (D'Agostino et al.), Which is incorporated herein by reference. The hydrophobic agent used is a fluorocarbon, i.e. perfluoromethylcyclohexane. The treated cellulosic web is disposed between the two barrier layers to form a three-layer absorbent barrier structure. Example 9a is substantially identical to Example 2 except that the treated BOUNTY (R) is used as the absorbent layer instead of the untreated BOUNTY (R). It has the same structure. Table 4 below shows the properties of this example compared to the example using the untreated web.
[0223]
[Table 5]

The results show that while the air permeability is maintained, the hydrophobic treatment significantly increases the liquid impermeability.
[0224]
(Example 10)
In this example, Example 3 and Comparative Example 2 are tested according to Test Method G (air permeability after compression). The results are summarized in Table 5 below.
[0225]
[Table 6]

Test results show that as a result of the compression, the air permeability of Example 3 of the absorbent barrier structure of the present invention has not substantially changed. In contrast, materials such as Comparative Example 2 have a significant loss of air permeability due to structural changes under compression and the inability to recover to the original structure.
[0226]
While particular embodiments of the present invention have been described, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
[Brief description of the drawings]
FIG. 1 is a top plan view, partially cut away, of an absorbent article containing the absorbent barrier structure of the present invention.
FIG. 2A is a cross-sectional view of an absorbent barrier structure of the present invention having a barrier layer and a storage layer.
FIG. 2B is a cross-sectional view of an absorbent barrier structure of the present invention having a storage layer disposed between two barrier layers.
FIG. 3A is a cross-sectional view of an alternative embodiment of the absorbent barrier structure of FIG. 2A.
FIG. 3B is a cross-sectional view of an alternative embodiment of the absorbent barrier structure of FIG. 2A.
FIG. 3C is a cross-sectional view of an alternative embodiment of the absorbent barrier structure of FIG. 2A.
FIG. 3D is a cross-sectional view of an alternative embodiment of the absorbent barrier structure of FIG. 2A.
FIG. 4A is a top plan view of an absorbent barrier structure of the present invention having a barrier region and a reservoir region in a side-by-side arrangement.
FIG. 4B is a top plan view of an alternative arrangement of the absorbent barrier structure of the present invention.
FIG. 5 is a schematic diagram of a dynamic liquid impact tester.

Claims (20)

An absorbent barrier structure, and an absorbent article including an absorbent core, wherein the absorbent barrier structure includes:
A head value of at least 10 mbar, preferably at least 30 mbar, more preferably at least 50 mbar, most preferably at least 75 mbar;
A convective air permeability of at least 10 Darcy / mm, preferably at least 30 Darcy / mm, most preferably at least 50 Darcy / mm;
Less than 10 g / ^{m 2,} more preferably has a dynamic liquid impact value of less than 6.5 g / ^{m 2,} the absorbent article. An absorbent article comprising a topsheet, an absorbent core, an absorbent barrier structure, and an outer cover,
The absorbent core is disposed between the topsheet and the outer cover;
The absorbent barrier structure is disposed between the absorbent core and the outer cover;
A combination of the absorbent barrier structure and the outer cover,
A head value of at least 10 mbar, preferably at least 30 mbar, more preferably at least 50 mbar, most preferably at least 75 mbar;
A convective air permeability of at least 10 Darcy / mm, preferably at least 30 Darcy / mm, most preferably at least 50 Darcy / mm;
Less than 10 g / ^{m 2,} more preferably has a dynamic liquid impact value of less than 6.5 g / ^{m 2,} the absorbent article. The absorbent article according to claim 1 or 2, wherein the absorbent barrier structure has an absorbency of at least 1 g / g, preferably 5 to 50 g / g, more preferably 10 to 30 g / g. Said absorbent barrier structure has less than 6.5 g / ^{m 2} in 2 minutes after impact, and 13 g / ^{m 2} less than the static liquid transfer value at 15 minutes after the shock (static liquid transmission value), according to claim 1 The absorbent article according to any one of claims 1 to 3. The absorbent barrier structure comprises a storage region, a barrier region at least partially disposed between the absorbent core and the storage region, and optionally at least a portion between the storage region and the outer cover. The absorbent article according to any one of claims 1 to 4, comprising a second barrier region arranged in a random manner. The storage area has an absorbency at least 20%, preferably at least 30% less than that of the absorbent core, wherein the head of the barrier area is lower than the head of the storage area and the head of the absorbent core. The absorbent article according to any one of claims 1 to 5, which is high. An absorbent article according to any of the preceding claims, wherein the head value of the barrier region is at least 10 mbar, preferably at least 30 mbar, more preferably at least 50 mbar, most preferably at least 75 mbar. . ^2. A moisture management means disposed between the absorbent barrier structure and the outer cover, or between the storage area and one of the barrier areas, having a MVTR of 4500 g / m < ² > / 24 hours or less. The absorbent article according to any one of claims 7 to 7. The storage area is a cellulosic web, the barrier area is a nonwoven web, the outer cover is a nonwoven web, a perforated film, or a laminate thereof, and the moisture management means has an open surface area of 20% or less. The absorbent article according to any one of claims 1 to 8, which is a perforated film. Wherein the storage area is from the group consisting of synthetic fibers, chemical adhesives, crosslinkers, bond weakeners, wet strength resins, liquid or moisture absorbers, odor absorbers, antimicrobial agents, colorants, curing agents, and mixtures thereof. The absorbent article according to any one of claims 1 to 9, further comprising a selected additive. An absorbent article according to any of the preceding claims, wherein at least one surface of the storage area or the barrier area is treated with a hydrophobic agent, preferably a fluorocarbon. A barrier structure, and an absorbent article comprising an absorbent core, wherein the barrier structure comprises:
A convective air permeability of greater than 10 Darcy / mm, preferably at least 30 Darcy / mm, most preferably at least 50 Darcy / mm;
A dynamic liquid impact value of less than 10 g / m ² , more preferably less than 6.5 g / m ² ;
An absorbent article having a reduced air permeability after compression of 35% or less, preferably 25% or less, and most preferably 15% or less. An absorbent article comprising a topsheet, an absorbent core, a barrier structure, and an outer cover,
The absorbent core is disposed between the topsheet and the outer cover;
The barrier structure is disposed between the absorbent core and an outer cover;
A combination of the barrier structure and the outer cover,
A convective air permeability of at least 10 Darcy / mm, preferably at least 30 Darcy / mm, most preferably at least 50 Darcy / mm;
A dynamic liquid impact value of less than 10 g / m ² , more preferably less than 6.5 g / m ² ;
An absorbent article having a reduced air permeability after compression of 35% or less, preferably 25% or less, most preferably 15% or less. Absorbent article according to claim 12 or 13, wherein the barrier structure has a head value of at least 10 mbar, preferably at least 30 mbar, more preferably at least 50 mbar, most preferably at least 75 mbar. A barrier region, wherein the barrier structure is disposed at least partially proximate to the absorbent core, and optionally at least partially disposed between the storage region and the outer cover. The absorbent article according to any one of claims 12 to 14, comprising a two-barrier region. 13. The storage area having an absorbency at least 20% less than that of an absorbent core, and the barrier area having a head value of the storage area and a head value higher than that of the absorbent core. The absorbent article according to any one of claims 15 to 15. 13. The moisture management means further disposed between the absorbent barrier structure and the outer cover or between the storage area and one of the barrier areas and having an MVTR of 4500 g / m < ² > / 24 hours or less. An absorbent article according to any one of the preceding items. The storage region is a cellulosic web having at least 70% by weight cellulosic fibers, the barrier region is a nonwoven web, the outer cover is a nonwoven web, a perforated film, or a laminate thereof, and the moisture management means is 20%. The absorbent article according to any one of claims 12 to 17, which is a perforated film having the following open surface area. Wherein the storage area is from the group consisting of synthetic fibers, chemical adhesives, crosslinkers, bond weakeners, wet strength resins, liquid or moisture absorbers, odor absorbers, antimicrobial agents, colorants, hardeners, and mixtures thereof. 19. The absorbent article according to any one of claims 12 to 18, further comprising a selected additive. 20. An absorbent article according to any one of claims 12 to 19, wherein at least one surface of the storage area or barrier area is treated with a hydrophobic agent, preferably a fluorocarbon.