JP3791982B2 - Absorbent articles - Google Patents

Description

【００１４】
また、本発明において用いられる上記の特定の高吸水性ポリマーは、下記（２）の特性を有する高吸水性ポリマーである。
【００１５】
（２）ＤＷ法による生理食塩水の吸水速度が５ｇ／３０秒／０．３ｇ以上、好ましくは６〜１５ｇ／３０秒／０．３ｇである。
【００１６】
上記吸水速度が、５ｇ／３０秒／０．３ｇ未満であると、吸水ポリマー自体が速く吸収することによる排泄液のストック能力が低下し、繊維状基材の使用量を低減することができない。
【００１７】
また、上記ＤＷ法による吸水速度については、後述する（実施例の記載参照）。
【００１８】
上記高吸水性ポリマー（Ｂ）としては、上記（２）を満足するものであれば特に制限されないが、具体的には例えば、ポリアクリル酸ソーダ、（アクリル酸−ビニルアルコール）共重合体、ポリアクリル酸ソーダ架橋体、（デンプン−アクリル酸）グラフト共重合体、（イソブチレン−無水マレイン酸）共重合体及びそのケン化物、ポリアクリル酸カリウム並びにポリアクリル酸セシウム等が挙げられ、粒子状あるいは繊維状にして用いることができる。
【００１９】
上記高吸水性ポリマー（Ａ）と上記高吸水性ポリマー（Ｂ）との使用比は、重量比（両者の合計量を１００とした場合の比）で高吸水性ポリマー（Ａ）：高吸水性ポリマー（Ｂ）＝８０〜５０：２０〜５０とする。上記高吸水性ポリマー（Ａ）の使用比が９０を超えると、排泄液のストック能力が低下し、３０未満であると、ゲルブロッキングを生じ、吸収性能が低下するので、上記範囲内とするのが好ましい。
【００２０】
また、本発明においては上記吸収体の構成材料として親水性の繊維状基材を用いることもできる。
上記繊維状基材としては、解繊されたパルプ繊維など、通常吸収性物品の吸収体に用いられる繊維材料が特に制限無く用いられる。
【００２１】
上記繊維状基材の配合割合は、吸収体全体の重量を１００重量部とした場合に、７０重量部以下とするのが好ましく、５〜４５重量部とするのが更に好ましい。
【００２２】
次に、上記吸収体の構造について図１〜４を参照して説明する。
ここで、図１〜４は、それぞれ本発明において用いられる吸収体の構造を模式的に示す拡大断面図である。
図１に示す吸収体１は、上記高吸水性ポリマー（Ａ）２からなる第１吸収層２０と、上記高吸水性ポリマー（Ｂ）３を含む第２吸収層３０と、該第１吸収層２０及び該第２吸収層３０それぞれの外面に位置する、通常のパルプ繊維などからなる通常の吸収紙からなる表裏２層の吸収紙層５０とからなる４層構造の積層体であり、更に、該高吸水性ポリマー（Ａ）２と該高吸水性ポリマー（Ｂ）３とが実質的に混合しないようになされている。
また、上記第２吸収層３０においては、上記高吸水性ポリマー（Ｂ）３は、繊維状基材４と混合されている。
【００２３】
図２に示す吸収体１ａは、上記高吸水性ポリマー（Ａ）２ａからなる第１吸収層２０ａと、上記高吸水性ポリマー（Ｂ）３ａを含む第２吸収層３０ａと、該第１吸収層２０ａ及び該第２吸収層３０ａそれぞれの外面に位置する吸収紙からなる表裏２層の吸収紙層５０ａとからなる４層構造の積層体であり、更に、該高吸水性ポリマー（Ａ）２ａと該高吸水性ポリマー（Ｂ）３ａとが実質的に混合しないようになされている。
また、上記第１吸収層２０ａにおいては、上記高吸水性ポリマー（Ａ）２ａは、繊維状基材４ａと混合されている。
【００２４】
図３に示す吸収体１ｂは、上記高吸水性ポリマー（Ａ）２ｂからなる第１吸収層２０ｂと、上記高吸水性ポリマー（Ｂ）３ｂを含む第２吸収層３０ｂと、該第１吸収層２０ｂ及び該第２吸収層３０ｂそれぞれの外面に位置する吸収紙からなる表裏２層の吸収紙層５０ｂとからなる４層構造の積層体であり、更に、該高吸水性ポリマー（Ａ）２ｂと該高吸水性ポリマー（Ｂ）３ｂとが実質的に混合しないようになされている。
また、上記第１吸収層２０ｂ及び上記第２吸収層３０ｂにおいては、上記高吸水性ポリマー（Ａ）２ｂ及び上記高吸水性ポリマー（Ｂ）３ｂは、それぞれ繊維状基材４ｂと混合されている。
【００２５】
図４に示す吸収体１ｃは、上記高吸水性ポリマー（Ａ）２ｃからなる第１吸収層２０ｃと、上記高吸水性ポリマー（Ｂ）３ｃを含む第２吸収層３０ｃとを有しており、更に、該高吸水性ポリマー（Ａ）２ｃと該高吸水性ポリマー（Ｂ）３ｃとが実質的に混合しないようになされている。
そして、上記第１吸収層２０ｃと上記第２吸収層３０ｃとは、繊維状基材４ｃからなる繊維状基材層４０ｃを介して互いに分離積層されており、上記吸収体１ｃは、該第１吸収層２０ｃと、該第２吸収層３０ｃと、該繊維状基材層４０ｃと、該第１吸収層２０ｃ及び該第２吸収層３０ｃそれぞれの外面に位置する吸収紙からなる表裏２層の吸収紙層５０ｃとからなる５層構造の積層体からなる。
【００２６】
尚、上記吸収紙層は無くても良く、また、表裏両面に設けずに何れか一面のみに設けることもできる。
【００２７】
上記吸収体は、その全体の坪量が、１００〜１０００ｇ／ｍ² であるのが好ましく、その厚みは、０．５〜５．０ｍｍであるのが好ましい。
【００２８】
上記吸収体の製造方法について説明すると、図１及び２に示す吸収体１，１ａは、上記第１吸収層と上記第２吸収層とのうち高吸水性ポリマーと繊維状基材とが混合されてなる方の層を、常法に従って高吸水性ポリマーと繊維状基材とを混合してウェブ状することにより形成した後、形成された層上に高吸水性ポリマーのみからなる層を形成し、更に吸収紙で挟持することにより製造することができる。
また、図３に示す吸収体１ｂは、上記第１吸収層と上記第２吸収層とを、それぞれ、常法に従って高吸水性ポリマーと繊維状基材とを混合してウェブ状することにより形成した後、上記第１吸収層と上記第２吸収層とを積層し、更に得られた積層体を吸収紙で挟持することにより製造することができる。
更に、図４に示す吸収体１ｃは、常法に従って、上記繊維状基材層を形成した後、該繊維状基材層の表裏表面に、高吸水性ポリマー（Ａ）及び（Ｂ）をそれぞれ積層し、得られた積層体を吸収紙で挟持することにより製造することができる。
【００２９】
次いで、上記吸収体を具備してなる本発明の吸収性物品について、図５を参照して説明する。
ここで、図５は、本発明の吸収性物品の１形態としての使い捨ておむつを示す平面図である。
尚、以下の説明においては、使い捨ておむつを例示して説明するが、本発明の吸収性物品としては、使い捨ておむつの他に、吸収体以外の部材は通常の部材からなり、通常の構造を有する、生理用ナプキンや失禁パッドなどが挙げられる。また、吸収体としては、図１に示す構造の吸収体を例示して説明するが、他の構造の吸収体も同様にして用いられる。
【００３０】
図５に示す本発明の吸収性物品としての使い捨ておむつ１０は、液透過性の表面シート１１と、液不透過性の裏面シート１２と、これら両シート間に介在する液保持性の吸収体１（図１に示す吸収体１）とを有する。
そして、上記吸収体１は、上記第１吸収層２０が表面シート１１側に位置し、上記第２吸収層３０が裏面シート１２側に位置するように配されている。
【００３１】
更に詳述すると、上記吸収体１はその股下領域が縊れた砂時計状に湾曲形成されている。また、上記表面シート１１及び上記裏面シート１２も上記吸収体１の形状に即してその股下領域が上述の如く湾曲形成されている。そして、上記吸収体１は、上記表面シート１１及び上記裏面シート１２により挟持・固定されている。
また、上記吸収体１の周縁部には、おむつを着用した際に、着用者にウエスト部１３及びレッグ部１４をフィットさせるための弾性伸縮部材１５が、それぞれ上記表面シート１１と上記裏面シート１２とにより挟持・固定されて設けられており、これにより、ウエスト部１３とレッグ部１４とに、それぞれウエストギャザー及びレッグギャザーが形成されている。
【００３２】
上記表面シート１１、上記裏面シート１２及び上記弾性伸縮部材１５の形成材料としては、通常吸収性物品に用いられるものが特に制限なく用いられる。
【００３３】
上記形態の使い捨ておむつ１は、上述の如く形成した上記吸収体１を用いて、通常公知の方法で製造することができる。
【００３４】
このような構成を有する上記使い捨ておむつ１は、吸収体が、薄型であっても、一回目の吸収がスムーズで、かつ２回目以降の吸収もゲルブロッキングによる吸収阻害を起こさないため、吸収性に優れ、もれないものである。
【００３５】
【実施例】
以下、実施例及び比較例により本発明を具体的に説明するが、本発明はこれらに限定されるものではない。
【００３６】
尚、以下の実施例及び比較例中における吸収体の評価は、下記の如くして行った。
吸収性の評価：得られた吸収体を２０ｃｍ＊２０ｃｍの大きさにカットして測定サンプルを得た。得られた測定サンプルに、生理食塩水５０ｍｌを一度に吸収させ、吸収の早さを下記の基準に従い評価した。評価は吸収体が飽和に達するまで何回か繰り返し行った。このうち、１回目と２回目の評価を〔表１〕に示す。
○：液の滞留が無く、素早い吸収が可能。
△：やや液が滞留し、表面を流れる傾向にある。
×：吸収が遅く、表面を流れる。
もれ率の評価：作成した使い捨ておむつを一般のモニター１０人に対して使用テストを行い、もれ率（尿もれ率）を求めた。
尚、もれ率は、下記の式により求めた。
式；もれ率（％）＝〔（尿モレが生じたおむつの枚数）／（アンケートに使用したおむつの全枚数）〕×１００
【００３７】
また、ＤＷ法による吸水速度の測定法は、以下の通りである。
ＤＷ法を実施する放置として一般的に知られている図６に示す装置（Demand Wettability Tester)を用い、図６に示す如く、生理食塩水Ｗの液面を等水位にセットしたポリマー散布台２（７０mmφ、No. ２濾紙をガラスフィルターNo. １に置いた台）上に、ポリマーＰを０．３ｇ散布し、ポリマーを散布した時点の吸水量を１とし、３０秒後の吸水量（この吸水量は、生理食塩水Ｗの水位の低下量を示すビュレットの目盛りで測定される）を測定し、この値を吸水速度とした。
【００３８】
〔実施例１〕
坪量１９ｇ／ｍ² の吸収紙上に、遠心脱水法による吸水量が２９ｇ／ｇで、液通過時間が１２秒である高吸水性ポリマー（Ａ−１）（ポリアクリル酸ソーダ架橋体粒子であって、表面部分の架橋密度が高いもの）を坪量１５０ｇ／ｍ² で積層して、第１吸収層を形成した。
次いで、解繊されたパルプ繊維１００重量部と吸水速度が６．５ｇ／３０秒／０．３ｇである高吸水性ポリマー（Ｂ−１）５０重量部とを均一に混合してなるウェブを上記第１吸収層上に坪量１５０ｇ／ｍ² で積層し〔高吸水性ポリマー（Ａ−１）の使用量／高吸水性ポリマー（Ｂ−１）の使用量比＝７５：２５〕、第２吸収層を形成した。更に、該第２吸収層上に坪量１９ｇ／ｍ² の吸収紙を積層して、図１に示す吸収体を得た。
吸収体の第１吸収層側に、繊維径３デニール、カット長５１ｍｍの芯成分がポリプロピレン、鞘成分がポリエチレンである複合繊維からなる不織布（親水化処理されたもの、坪量２５ｇ／ｍ² ）を表面シートとして配するとともに、第２吸収層側に裏面シートとしてポリエチレンシートを配し、図５に示す使い捨ておむつを得た。
得られた吸収体及び使い捨ておむつについて、吸水性及びもれ率を評価した。その結果を〔表１〕に示す。
【００３９】
〔実施例２〕
第１吸収層の坪量を７５ｇ／ｍ² とし、高吸水性ポリマー（Ｂ−１）の使用量を１００重量部として、高吸水性ポリマー（Ａ−１）と高吸水性ポリマー（Ｂ−１）との使用量比を５０：５０とした以外は、実施例１と同様にして、吸収体及び使い捨ておむつを得た。
得られた吸収体及び使い捨ておむつについて、吸水性及びもれ率を評価した。その結果を〔表１〕に示す。
【００４０】
〔実施例３〕
坪量５０ｇ／ｍ² の乾式パルプからなる不織布上に、吸水速度が１０ｇ／３０秒／０．３ｇである高吸水ポリマー（Ｂ−２）を坪量５０ｇ／ｍ² で積層して、吸収紙層及び第２吸収層を形成した。
次いで、繊維径２デニール、カット長５１ｍｍの芯がポリエチレンテレフタレート、鞘成分がポリエチレンからなる複合繊維からなる不織布（親水化処理されたもの、坪量２２ｇ／ｍ² ）を第２吸収層上に積層し（繊維状基材層）、更に実施例１で用いたのと同じ高吸水性ポリマー（Ａ−１）を坪量１５０ｇ／ｍ² で積層し〔高吸水性ポリマー（Ａ−１）の使用量：高吸水性ポリマー（Ｂ−２）の使用量比＝７５：２５〕た以外は実施例１と同様にして、図４に示す構造の吸収体及び図５に示す構造の使い捨ておむつを得た。
得られた吸収体及び使い捨ておむつについて、吸水性及びもれ率を評価した。その結果を〔表１〕に示す。
【００４１】
〔比較例１〕
坪量１９ｇ／ｍ² の吸収紙上に、解繊されたパルプ繊維１００重量部と遠心脱水法による吸水量が２９ｇ／ｇで、液通過時間が１２秒である高吸水性ポリマー（Ａ−１）（ポリアクリル酸ソーダ架橋体粒子であって、表面部分の架橋密度が高いもの）１７０重量部とを均一に混合してなるウエブを坪量３００ｇ／ｍ² で積層し、更にこの上に坪量１９ｇ／ｍ² の吸収紙を積層した以外は、実施例１と同様にして、吸収体及び使い捨ておむつを得た。
得られた吸収体及び使い捨ておむつについて、吸水性及びもれ率を評価した。その結果を〔表１〕に示す。
【００４２】
〔比較例２〕
高吸水性ポリマー（Ａ−１）に代えて吸収速度６ｇ／３０秒／０．３ｇの高吸水性ポリマー（Ｂ−１）を用いた以外は比較例１と同様にして、吸収体及び使い捨ておむつを得た。
得られた吸収体及び使い捨ておむつについて、吸水性及びもれ率を評価した。その結果を〔表１〕に示す。
【００４３】
〔比較例３〕
解繊されたパルプ繊維１００重量部と高吸水性ポリマー（Ａ−１）１５０重量部と高吸水性ポリマー（Ｂ−１）５０重量部とを均一に混合してウエブを得、得られたウェブを坪量１９ｇ／ｍ² の吸収紙上に坪量３００ｇ／ｍ² で積層した〔高吸水性ポリマー（Ａ−１）の使用量：高吸水性ポリマー（Ｂ−１）の使用量比＝７５：２５〕以外は実施例１と同様にして、吸収体及び使い捨ておむつを得た。
得られた吸収体及び使い捨ておむつについて、吸水性及びもれ率を評価した。その結果を〔表１〕に示す。
【００４４】
【表１】

【００４５】
【発明の効果】
本発明の吸収性物品は、吸収体が薄型であって、高吸水性ポリマーのゲルブロッキングなどにより、吸収性の低下が生じず、漏れを生じないものである。
【図面の簡単な説明】
【図１】図１は、本発明において用いられる吸収体の構造を模式的に示す拡大断面図である。
【図２】図２は、本発明において用いられる吸収体の構造を模式的に示す拡大断面図である。
【図３】図３は、本発明において用いられる吸収体の構造を模式的に示す拡大断面図である。
【図４】図４は、本発明において用いられる吸収体の構造を模式的に示す拡大断面図である。
【図５】図５は、本発明の吸収性物品の１形態としての使い捨ておむつを示す平面図である。
【図６】図６は、ＤＷ法による吸収速度の測定装置の概略図である。
【符号の説明】
１ 吸収体
２ 高吸水性ポリマー（Ａ）
３ 高吸水性ポリマー（Ｂ）
４ 繊維状基材
２０ 第１吸収層
３０ 第２吸収層
４０ 繊維状基材層
５０ 吸収紙層
１０ 使い捨ておむつ
１１ 表面シート
１２ 裏面シート
１３ ウエスト部
１４ レッグ部
１５ 弾性部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to absorbent articles such as sanitary napkins, disposable diapers, and incontinence pads. More specifically, the present invention relates to an absorbent article having excellent absorbency, high fit, and excellent leakage prevention.
[0002]
[Prior art and problems to be solved by the invention]
Absorbent articles such as sanitary napkins, disposable diapers, and incontinence pads having a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorbent interposed between the two sheets, Widely used.
In such an absorbent article, it is demanded that the absorbent article has high absorbency and the thickness of the absorbent article itself is thin, compact, and not bulky. For this reason, it is proposed to reduce the thickness of the absorbent body. .
The absorbent body is generally composed of a fibrous base material typified by pulp fiber and a superabsorbent polymer, and the absorption of excretory fluid is first stocked on the fibrous base material, and then the superabsorbent polymer is absorbed. This is done by fixing.
[0003]
However, in order to reduce the thickness of the absorber, it is necessary to reduce the amount of the fibrous base material used, so that the stock capacity of excretory liquid is reduced, and further gel blocking of the superabsorbent polymer occurs. There was a problem that this occurred.
[0004]
Therefore, an object of the present invention is to provide an absorbent article that has a thin absorbent body, does not cause a decrease in stock ability of excretory liquid, and does not cause a decrease in absorbability due to gel blocking of a superabsorbent polymer, and does not leak. There is to do.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that a first absorbent layer having a specific superabsorbent polymer and a second absorbent layer having a specific superabsorbent polymer have their respective superabsorbent water absorption. It has been found that an absorbent article having an absorbent body formed so as not to be mixed with a conductive polymer can achieve the above object.
[0006]
The present invention has been made based on the above knowledge, and has an absorbent article having a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorbent interposed between the two sheets. In the above, the absorbent comprises a first absorbent layer containing a superabsorbent polymer (A) having the following characteristics (1) and a second absorbent comprising a superabsorbent polymer (B) having the following characteristics (2): The superabsorbent polymer (A) and the superabsorbent polymer (B) are not substantially mixed with each other, and the first absorbent layer has the surface. Located on the sheet side, the second absorbent layer is disposed on the back sheet side, and the usage ratio of the superabsorbent polymer (A) to the superabsorbent polymer (B) is weight. Ratio of superabsorbent polymer (A): superabsorbent polymer (B) = 80-50 It is to provide an absorbent article, characterized in that 20 to 50.
(1) Liquid permeation time [Closing the highly water-absorbing polymer 0.5 g to a cylinder with a cross-sectional area of 4.91 cm ² (inner diameter 25 mmφ) and an openable / closable cock (inner diameter 4 mmφ). Fill with physiological saline and swell the superabsorbent polymer with the physiological saline until it reaches saturation. After the swollen superabsorbent polymer settles, open the cock and allow 50 ml of physiological saline to pass through. The time required for 50 ml of the physiological saline to pass through is 20 seconds or less.
(2) The physiological water absorption rate by the DW method is 5 g / 30 sec / 0.3 g or more.
[0007]
Moreover, this invention provides the said absorbent article in which the crosslinking density gradient is provided in the particle | grain surface of the said highly water-absorbing polymer (A) . In the present invention, at least one of the first absorbent layer and the second absorbent layer is a fibrous base material in which the superabsorbent polymer (A) or the superabsorbent polymer (B) is hydrophilic. The absorbent article is formed by being mixed with the absorbent article. Further, the present invention provides the absorbent article, wherein the first absorbent layer and the second absorbent layer are separated from each other via a fibrous base material layer made of a fibrous base material. It is to provide. In the present invention, the blending ratio of the fibrous base material is 5 to 45 parts by weight when the weight of the whole absorbent body is 100 parts by weight, and the absorbent has a basis weight of the whole. 100 to 1000 g / m ² of the absorbent article.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the absorbent article of the present invention will be described in detail.
In the absorbent article of the present invention, the absorbent has a first absorbent layer having a specific superabsorbent polymer (A) and a second absorbent layer having a specific superabsorbent polymer (B), The superabsorbent polymer (A) and the superabsorbent polymer (B) are not substantially mixed.
Here, “substantially not mix” means that the superabsorbent polymers (A) and (B) do not interfere with each other.
In this way, in order to achieve a “substantially not mixed” configuration, as described later, at least one of the first absorbent layer and the second absorbent layer is composed of the superabsorbent polymer (A) or the above. A fiber in which the superabsorbent polymer (B) is formed by mixing with a hydrophilic fibrous base material, or the first absorbent layer and the second absorbent layer are made of a fibrous base material. It is preferable to have a structure in which the layers are separated and laminated with each other through a shaped base layer.
Further, the first absorbent layer is constituted only by the superabsorbent polymer (A), the second absorbent layer is constituted only by the superabsorbent polymer (B), and the first absorbent layer and the second absorbent layer are constituted. You may laminate | stack a layer. In this case, although it is difficult to completely separate the superabsorbent polymer (A) and the superabsorbent polymer (B), they do not impair each other's characteristics even if there are some mixed parts. It can be said that it is “substantially not mixed” in a mixed state of a degree. For example, a portion in which the superabsorbent polymer (B) of less than 30 wt% is mixed in the first absorbent layer (near the interface with the second absorbent layer) with respect to the total amount of the superabsorbent polymer (A) (particularly, Even if there is an interface portion), it can be said that it is in a state of “substantially not mixing” if it is at this level.
[0009]
The specific superabsorbent polymer (A) used in the present invention is a superabsorbent polymer having the following property (1).
[0010]
(1) Liquid passage time [Closing the superabsorbent polymer 0.5 g in a cylinder with a cross-sectional area of 4.91 cm ² (inner diameter 25 mmφ) and an openable / closable cock (inner diameter 4 mmφ) at the bottom. Fill with physiological saline, swell the superabsorbent polymer with the physiological saline until it reaches saturation, and after the swelled superabsorbent polymer settles, open the cock and allow 50 ml of physiological saline to pass through. The time required for 50 ml of the physiological saline to pass through is 20 seconds or less, preferably 2 to 15 seconds. When the liquid passage time exceeds 20 seconds, gel blocking occurs, so that the absorption performance decreases.
[0011]
The superabsorbent polymer (A) is not particularly limited as long as it satisfies the above-mentioned characteristics (1). Specific examples include sodium polyacrylate and (acrylic acid-vinyl alcohol) copolymer. , Cross-linked poly (sodium acrylate), (starch-acrylic acid) graft polymer, (isobutylene-maleic anhydride) copolymer and saponified product thereof, potassium polyacrylate, and cesium polyacrylate.
In order to satisfy the condition (1), for example, a crosslink density gradient is provided on the surface of the superabsorbent polymer particles, or the superabsorbent polymer particles are non-spherical amorphous particles. More specifically, the method described in JP-A-7-18495, column 7 line 28 to column 9 line 6 can be used.
[0012]
The superabsorbent polymer (A) has a physiological water absorption of 25 g / g or more, more preferably 35 to 65 g / g, by the centrifugal dehydration method. Here, the “water absorption amount by centrifugal dehydration method” is measured as follows.
<Water absorption by centrifugal dehydration of super absorbent polymer>
1 g of the superabsorbent polymer was swollen with 150 ml of physiological saline for 30 minutes, then placed in a 250 mesh nylon mesh bag, dehydrated with a centrifuge at 143 G for 10 minutes, and the total weight after dehydration was measured. Subsequently, the amount of water absorption (g / g) by centrifugal dehydration was calculated according to the mathematical formula shown in [Formula 1] below.
[0013]
[Expression 1]

[0014]
The specific superabsorbent polymer used in the present invention is a superabsorbent polymer having the following property (2).
[0015]
(2) The physiological water absorption rate by the DW method is 5 g / 30 sec / 0.3 g or more, preferably 6 to 15 g / 30 sec / 0.3 g.
[0016]
When the water absorption rate is less than 5 g / 30 seconds / 0.3 g, the stock capacity of excreta due to the rapid absorption of the water-absorbing polymer itself decreases, and the amount of fibrous base material used cannot be reduced.
[0017]
Moreover, the water absorption rate by the DW method will be described later (see the description of the examples).
[0018]
The superabsorbent polymer (B) is not particularly limited as long as it satisfies the above (2). Specifically, for example, polyacrylic acid soda, (acrylic acid-vinyl alcohol) copolymer, poly Examples include sodium acrylate cross-linked product, (starch-acrylic acid) graft copolymer, (isobutylene-maleic anhydride) copolymer and saponified product thereof, potassium polyacrylate, and cesium polyacrylate. Can be used.
[0019]
The use ratio of the superabsorbent polymer (A) to the superabsorbent polymer (B) is a weight ratio (a ratio when the total amount of both is 100), and the superabsorbent polymer (A): superabsorbent polymer. polymer (B) = 8 0~50: you 20 to 50. When the use ratio of the superabsorbent polymer (A) exceeds 90, the stock capacity of excretory liquid decreases, and when it is less than 30, gel blocking occurs and the absorption performance decreases. Is preferred.
[0020]
In the present invention, a hydrophilic fibrous base material can also be used as a constituent material of the absorber.
As the fibrous base material, fiber materials that are usually used for absorbent bodies of absorbent articles, such as defibrated pulp fibers, are used without particular limitation.
[0021]
The blending ratio of the fibrous base material is preferably 70 parts by weight or less, more preferably 5 to 45 parts by weight, when the weight of the entire absorbent body is 100 parts by weight.
[0022]
Next, the structure of the absorber will be described with reference to FIGS.
1 to 4 are enlarged cross-sectional views schematically showing the structure of the absorber used in the present invention.
The absorbent body 1 shown in FIG. 1 includes a first absorbent layer 20 made of the superabsorbent polymer (A) 2, a second absorbent layer 30 containing the superabsorbent polymer (B) 3, and the first absorbent layer. 20 and the second absorbent layer 30, each of which is a laminate having a four-layer structure comprising two front and back absorbent paper layers 50 made of ordinary absorbent paper made of ordinary pulp fibers and the like. The superabsorbent polymer (A) 2 and the superabsorbent polymer (B) 3 are not substantially mixed.
In the second absorbent layer 30, the superabsorbent polymer (B) 3 is mixed with the fibrous base material 4.
[0023]
An absorbent body 1a shown in FIG. 2 includes a first absorbent layer 20a made of the super absorbent polymer (A) 2a, a second absorbent layer 30a containing the super absorbent polymer (B) 3a, and the first absorbent layer. 20a and a laminated body having a four-layer structure comprising two absorbent paper layers 50a made of absorbent paper located on the outer surface of each of the second absorbent layers 30a, and the superabsorbent polymer (A) 2a The superabsorbent polymer (B) 3a is not substantially mixed.
In the first absorbent layer 20a, the superabsorbent polymer (A) 2a is mixed with the fibrous base material 4a.
[0024]
The absorber 1b shown in FIG. 3 includes a first absorbent layer 20b made of the superabsorbent polymer (A) 2b, a second absorbent layer 30b containing the superabsorbent polymer (B) 3b, and the first absorbent layer. 20b and a two-layered absorbent paper layer 50b made of absorbent paper located on the outer surface of each of the second absorbent layers 30b. Further, the superabsorbent polymer (A) 2b and The superabsorbent polymer (B) 3b is not substantially mixed.
In the first absorbent layer 20b and the second absorbent layer 30b, the superabsorbent polymer (A) 2b and the superabsorbent polymer (B) 3b are each mixed with the fibrous base material 4b. .
[0025]
The absorber 1c shown in FIG. 4 has a first absorbent layer 20c made of the superabsorbent polymer (A) 2c and a second absorbent layer 30c containing the superabsorbent polymer (B) 3c. Further, the superabsorbent polymer (A) 2c and the superabsorbent polymer (B) 3c are not substantially mixed.
And the said 1st absorption layer 20c and the said 2nd absorption layer 30c are mutually separated and laminated | stacked through the fibrous base material layer 40c which consists of the fibrous base material 4c, The said absorber 1c is said 1st Absorption of front and back two layers made of absorbent paper located on the outer surfaces of the absorbent layer 20c, the second absorbent layer 30c, the fibrous base material layer 40c, and the first absorbent layer 20c and the second absorbent layer 30c. It consists of the laminated body of the 5 layer structure which consists of the paper layer 50c.
[0026]
The absorbent paper layer may not be provided, and may be provided on only one surface without being provided on both the front and back surfaces.
[0027]
The absorbent body preferably has an overall basis weight of 100 to 1000 g / m ² and a thickness of 0.5 to 5.0 mm.
[0028]
Explaining the manufacturing method of the absorbent body, the absorbent bodies 1 and 1a shown in FIGS. 1 and 2 are obtained by mixing a superabsorbent polymer and a fibrous base material out of the first absorbent layer and the second absorbent layer. And forming a layer composed of only the superabsorbent polymer on the formed layer after forming the web layer by mixing the superabsorbent polymer and the fibrous base material according to a conventional method. Further, it can be produced by sandwiching with absorbent paper.
Moreover, the absorber 1b shown in FIG. 3 is formed by mixing the first absorbent layer and the second absorbent layer, respectively, by mixing a superabsorbent polymer and a fibrous base material according to a conventional method. Then, the first absorbent layer and the second absorbent layer can be laminated, and the obtained laminate can be further sandwiched between absorbent papers.
Further, in the absorbent body 1c shown in FIG. 4, after forming the fibrous base material layer according to a conventional method, the superabsorbent polymers (A) and (B) are respectively formed on the front and back surfaces of the fibrous base material layer. It can manufacture by laminating | stacking and pinching the obtained laminated body with an absorbent paper.
[0029]
Next, the absorbent article of the present invention comprising the above absorbent body will be described with reference to FIG.
Here, FIG. 5 is a top view which shows the disposable diaper as 1 form of the absorbent article of this invention.
In the following description, a disposable diaper is illustrated as an example. However, as the absorbent article of the present invention, in addition to the disposable diaper, members other than the absorbent body are made of ordinary members and have a usual structure. And sanitary napkins and incontinence pads. Moreover, as an absorber, although the absorber of the structure shown in FIG. 1 is illustrated and demonstrated, the absorber of another structure is used similarly.
[0030]
A disposable diaper 10 as an absorbent article of the present invention shown in FIG. 5 includes a liquid-permeable top sheet 11, a liquid-impermeable back sheet 12, and a liquid-retaining absorbent body 1 interposed between these sheets. (Absorber 1 shown in FIG. 1).
And the said absorber 1 is distribute | arranged so that the said 1st absorption layer 20 may be located in the surface sheet 11 side, and the said 2nd absorption layer 30 may be located in the back sheet 12 side.
[0031]
More specifically, the absorber 1 is curved and formed in an hourglass shape in which the crotch region is curled. Also, the crotch region of the top sheet 11 and the back sheet 12 is curved as described above in accordance with the shape of the absorber 1. The absorber 1 is sandwiched and fixed by the top sheet 11 and the back sheet 12.
Moreover, when the diaper is worn on the peripheral portion of the absorbent body 1, elastic elastic members 15 for fitting the waist portion 13 and the leg portion 14 to the wearer are respectively the top sheet 11 and the back sheet 12. The waist gathers and the leg gathers are formed in the waist part 13 and the leg part 14, respectively.
[0032]
As a material for forming the top sheet 11, the back sheet 12, and the elastic elastic member 15, those normally used for absorbent articles are used without particular limitation.
[0033]
The disposable diaper 1 of the said form can be normally manufactured by a well-known method using the said absorber 1 formed as mentioned above.
[0034]
The disposable diaper 1 having such a configuration is absorbent even if the absorbent body is thin, since the first absorption is smooth and the second and subsequent absorptions do not inhibit absorption due to gel blocking. It is excellent and cannot be lost.
[0035]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these.
[0036]
In addition, evaluation of the absorber in the following examples and comparative examples was performed as follows.
Evaluation of absorbency: The obtained absorber was cut into a size of 20 cm * 20 cm to obtain a measurement sample. The obtained measurement sample was allowed to absorb 50 ml of physiological saline at a time, and the speed of absorption was evaluated according to the following criteria. The evaluation was repeated several times until the absorber reached saturation. Of these, the first and second evaluations are shown in [Table 1].
○: No liquid retention and quick absorption.
Δ: Some liquid stays and tends to flow on the surface.
X: Absorption is slow and flows on the surface.
Evaluation of Leakage Rate: The disposable diapers thus prepared were subjected to a use test on 10 general monitors, and the leak rate (urine leak rate) was determined.
In addition, the leak rate was calculated | required by the following formula.
Formula: Leakage rate (%) = [(Number of diapers with urine leakage) / (Total number of diapers used in the questionnaire)] × 100
[0037]
Moreover, the measuring method of the water absorption rate by DW method is as follows.
Using a device (Demand Wettability Tester) shown in FIG. 6 that is generally known as neglected to carry out the DW method, as shown in FIG. 6, a polymer spray table 2 in which the level of the physiological saline W is set at an equal water level. (70 mmφ, No. 2 filter paper placed on glass filter No. 1) 0.3 g of polymer P is sprayed, the water absorption at the time when the polymer is sprayed is 1, and the water absorption after 30 seconds (this The amount of water absorption was measured by a burette scale indicating the amount of decrease in the level of the physiological saline W), and this value was taken as the water absorption rate.
[0038]
[Example 1]
^On an absorbent paper having a basis weight of 19 g / m ² , a superabsorbent polymer (A-1) having a water absorption amount by centrifugal dehydration of 29 g / g and a liquid passage time of 12 seconds (cross-linked sodium polyacrylate particles). The first absorbent layer was formed by laminating a surface portion having a high crosslinking density) at a basis weight of 150 g / m ² .
Next, a web obtained by uniformly mixing 100 parts by weight of the pulverized pulp fiber and 50 parts by weight of the superabsorbent polymer (B-1) having a water absorption rate of 6.5 g / 30 seconds / 0.3 g is obtained as described above. Laminated on the first absorbent layer at a basis weight of 150 g / m ² [use ratio of superabsorbent polymer (A-1) / use ratio of superabsorbent polymer (B-1) = 75: 25], second An absorbent layer was formed. Further, an absorbent paper having a basis weight of 19 g / m ² was laminated on the second absorbent layer to obtain an absorbent body shown in FIG.
On the first absorbent layer side of the absorbent body, a nonwoven fabric composed of a composite fiber having a fiber diameter of 3 denier, a core component having a cut length of 51 mm, and a sheath component made of polyethylene (hydrophilized, basis weight 25 g / m ² ) Was disposed as a top sheet and a polyethylene sheet was disposed as a back sheet on the second absorbent layer side to obtain a disposable diaper shown in FIG.
About the obtained absorber and disposable diaper, the water absorption and the leak rate were evaluated. The results are shown in [Table 1].
[0039]
[Example 2]
The basis weight of the first absorbent layer is 75 g / m ² , the amount of the superabsorbent polymer (B-1) used is 100 parts by weight, and the superabsorbent polymer (A-1) and superabsorbent polymer (B-1) are used. ) And an absorbent body and a disposable diaper were obtained in the same manner as in Example 1 except that the usage ratio was 50:50.
About the obtained absorber and disposable diaper, the water absorption and the leak rate were evaluated. The results are shown in [Table 1].
[0040]
Example 3
A superabsorbent polymer (B-2) having a water absorption rate of 10 g / 30 seconds / 0.3 g is laminated on a nonwoven fabric made of dry pulp having a basis weight of 50 g / m ^{2 at} a basis weight of 50 g / m ² , and absorbent paper. A layer and a second absorbent layer were formed.
Next, a non-woven fabric (hydrophilized, basis weight 22 g / m ² ) made of a composite fiber having a fiber diameter of 2 denier, a core having a cut length of 51 mm and polyethylene terephthalate and a sheath component made of polyethylene is laminated on the second absorbent layer. (Fibrous substrate layer), and the same superabsorbent polymer (A-1) used in Example 1 was laminated at a basis weight of 150 g / m ² [use of superabsorbent polymer (A-1) The amount of the superabsorbent polymer (B-2) used amount ratio = 75: 25] was obtained in the same manner as in Example 1 to obtain an absorbent body having the structure shown in FIG. 4 and a disposable diaper having the structure shown in FIG. It was.
About the obtained absorber and disposable diaper, the water absorption and the leak rate were evaluated. The results are shown in [Table 1].
[0041]
[Comparative Example 1]
Superabsorbent polymer (A-1) having 100 parts by weight of pulverized pulp fiber, water absorption by centrifugal dehydration method of 29 g / g, and liquid passage time of 12 seconds on absorbent paper having a basis weight of 19 g / m ² (Polysodium acrylate cross-linked particles having a high cross-linking density in the surface portion) A web obtained by uniformly mixing 170 parts by weight with a basis weight of 300 g / m ² is laminated, and a basis weight is further formed thereon. An absorbent body and a disposable diaper were obtained in the same manner as in Example 1 except that 19 g / m ² of absorbent paper was laminated.
About the obtained absorber and disposable diaper, the water absorption and the leak rate were evaluated. The results are shown in [Table 1].
[0042]
[Comparative Example 2]
Absorber and disposable diaper in the same manner as in Comparative Example 1 except that the superabsorbent polymer (B-1) having an absorption rate of 6 g / 30 seconds / 0.3 g was used instead of the superabsorbent polymer (A-1). Got.
About the obtained absorber and disposable diaper, the water absorption and the leak rate were evaluated. The results are shown in [Table 1].
[0043]
[Comparative Example 3]
A web obtained by uniformly mixing 100 parts by weight of the pulverized pulp fiber, 150 parts by weight of the superabsorbent polymer (A-1) and 50 parts by weight of the superabsorbent polymer (B-1), and obtaining the web Was laminated on an absorbent paper having a basis weight of 19 g / m ^{2 at} a basis weight of 300 g / m ² [Use amount of superabsorbent polymer (A-1): Use ratio of superabsorbent polymer (B-1) = 75: Except for 25], an absorbent body and a disposable diaper were obtained in the same manner as in Example 1.
About the obtained absorber and disposable diaper, the water absorption and the leak rate were evaluated. The results are shown in [Table 1].
[0044]
[Table 1]

[0045]
【The invention's effect】
The absorbent article of the present invention has a thin absorbent body and does not cause a decrease in absorbability due to gel blocking of a highly water-absorbing polymer, and does not leak.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view schematically showing the structure of an absorber used in the present invention.
FIG. 2 is an enlarged cross-sectional view schematically showing the structure of an absorber used in the present invention.
FIG. 3 is an enlarged cross-sectional view schematically showing the structure of an absorber used in the present invention.
FIG. 4 is an enlarged cross-sectional view schematically showing the structure of an absorber used in the present invention.
FIG. 5 is a plan view showing a disposable diaper as one embodiment of the absorbent article of the present invention.
FIG. 6 is a schematic diagram of an apparatus for measuring an absorption rate by the DW method.
[Explanation of symbols]
1 Absorber 2 Superabsorbent polymer (A)
3 Super absorbent polymer (B)
4 fibrous base material 20 first absorbent layer 30 second absorbent layer 40 fibrous base material layer 50 absorbent paper layer 10 disposable diaper 11 topsheet 12 backsheet 13 waist portion 14 leg portion 15 elastic member

Claims (5)

In an absorbent article having a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorbent interposed between the two sheets,
The absorber comprises a first absorbent layer containing a superabsorbent polymer (A) having the following characteristics (1), and a second absorbent layer comprising a superabsorbent polymer (B) having the following (2) characteristics: In addition, the superabsorbent polymer (A) and the superabsorbent polymer (B) are not substantially mixed, and the first absorbent layer is on the surface sheet side. And the second absorbent layer is arranged to be located on the back sheet side ,
The use ratio of the superabsorbent polymer (A) to the superabsorbent polymer (B) is such that the superabsorbent polymer (A): superabsorbent polymer (B) = 80-50: 20-50 in weight ratio. absorbent article, characterized in that.
(1) Liquid permeation time [The superabsorbent polymer 0.5 g was closed to a cylinder with a cross-sectional area of 4.91 cm ² (inner diameter 25 mmφ) and an openable / closable cock (inner diameter 4 mmφ). Fill with physiological saline and swell the superabsorbent polymer with the physiological saline until it reaches saturation. After the swelled superabsorbent polymer settles, open the cock and allow 50 ml of physiological saline to pass through. The time required for 50 ml of the physiological saline to pass through is 20 seconds or less.
(2) The physiological water absorption rate by the DW method is 5 g / 30 sec / 0.3 g or more. The absorbent article according to claim 1 , wherein a crosslink density gradient is provided on the particle surface of the superabsorbent polymer (A) .   At least one of the first absorbent layer and the second absorbent layer is formed by mixing the superabsorbent polymer (A) or the superabsorbent polymer (B) with a hydrophilic fibrous base material. The absorptive article according to claim 1 or 2 characterized by things.   The said absorber is the said 1st absorption layer and the said 2nd absorption layer being mutually separated and laminated | stacked through the fibrous base material layer which consists of a fibrous base material. The absorbent article in any one. The blending ratio of the fibrous base material is 5 to 45 parts by weight when the weight of the entire absorbent body is 100 parts by weight,
The above-mentioned absorber has a total basis weight of 100 to 1000 g / m. ² The absorbent article according to claim 3 or 4, wherein the absorbent article is.

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