JP4583516B2 - Water absorbent resin, method for producing the same, and absorbent article - Google Patents
Water absorbent resin, method for producing the same, and absorbent article Download PDFInfo
- Publication number
- JP4583516B2 JP4583516B2 JP05240298A JP5240298A JP4583516B2 JP 4583516 B2 JP4583516 B2 JP 4583516B2 JP 05240298 A JP05240298 A JP 05240298A JP 5240298 A JP5240298 A JP 5240298A JP 4583516 B2 JP4583516 B2 JP 4583516B2
- Authority
- JP
- Japan
- Prior art keywords
- water
- absorbent resin
- blood
- resin
- particle size
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000011347 resin Substances 0.000 title claims description 245
- 229920005989 resin Polymers 0.000 title claims description 245
- 239000002250 absorbent Substances 0.000 title claims description 173
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 119
- 230000002745 absorbent Effects 0.000 title claims description 118
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 239000002245 particle Substances 0.000 claims description 91
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 36
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 claims description 24
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 22
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims description 21
- 238000009826 distribution Methods 0.000 claims description 21
- 235000011187 glycerol Nutrition 0.000 claims description 16
- 239000003431 cross linking reagent Substances 0.000 claims description 14
- 238000002156 mixing Methods 0.000 claims description 13
- 239000000178 monomer Substances 0.000 claims description 12
- 150000005846 sugar alcohols Polymers 0.000 claims description 9
- 238000004132 cross linking Methods 0.000 claims description 8
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical compound OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 claims description 6
- GPLRAVKSCUXZTP-UHFFFAOYSA-N diglycerol Chemical compound OCC(O)COCC(O)CO GPLRAVKSCUXZTP-UHFFFAOYSA-N 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 4
- 230000000379 polymerizing effect Effects 0.000 claims description 4
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 3
- 229940105990 diglycerin Drugs 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 2
- 210000004369 blood Anatomy 0.000 description 140
- 239000008280 blood Substances 0.000 description 140
- 238000010521 absorption reaction Methods 0.000 description 59
- 239000000499 gel Substances 0.000 description 28
- 230000000052 comparative effect Effects 0.000 description 21
- 239000007788 liquid Substances 0.000 description 19
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 17
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 14
- 229940048053 acrylate Drugs 0.000 description 14
- -1 2-hydroxypropyl Chemical group 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 10
- 239000000203 mixture Substances 0.000 description 10
- 210000000601 blood cell Anatomy 0.000 description 9
- 239000000306 component Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 229920001223 polyethylene glycol Polymers 0.000 description 7
- 229920000642 polymer Polymers 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000000835 fiber Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 4
- 239000002202 Polyethylene glycol Substances 0.000 description 4
- 210000002700 urine Anatomy 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical compound CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 229940059574 pentaerithrityl Drugs 0.000 description 3
- WXZMFSXDPGVJKK-UHFFFAOYSA-N pentaerythritol Chemical compound OCC(CO)(CO)CO WXZMFSXDPGVJKK-UHFFFAOYSA-N 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- YPFDHNVEDLHUCE-UHFFFAOYSA-N propane-1,3-diol Chemical compound OCCCO YPFDHNVEDLHUCE-UHFFFAOYSA-N 0.000 description 3
- 229940113165 trimethylolpropane Drugs 0.000 description 3
- AUZRCMMVHXRSGT-UHFFFAOYSA-N 2-methylpropane-1-sulfonic acid;prop-2-enamide Chemical compound NC(=O)C=C.CC(C)CS(O)(=O)=O AUZRCMMVHXRSGT-UHFFFAOYSA-N 0.000 description 2
- WOAMRAPSJUZQJV-UHFFFAOYSA-N 3-oxopent-4-ene-2-sulfonic acid Chemical compound OS(=O)(=O)C(C)C(=O)C=C WOAMRAPSJUZQJV-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229920000742 Cotton Polymers 0.000 description 2
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- 241001494479 Pecora Species 0.000 description 2
- 229920002873 Polyethylenimine Polymers 0.000 description 2
- 229920001131 Pulp (paper) Polymers 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 2
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 description 2
- WERYXYBDKMZEQL-UHFFFAOYSA-N butane-1,4-diol Chemical compound OCCCCO WERYXYBDKMZEQL-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 235000014113 dietary fatty acids Nutrition 0.000 description 2
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 2
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 150000002170 ethers Chemical class 0.000 description 2
- 239000000194 fatty acid Substances 0.000 description 2
- 229930195729 fatty acid Natural products 0.000 description 2
- 239000003337 fertilizer Substances 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- 229920000578 graft copolymer Polymers 0.000 description 2
- 239000000017 hydrogel Substances 0.000 description 2
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 2
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- IVDFJHOHABJVEH-UHFFFAOYSA-N pinacol Chemical compound CC(C)(O)C(C)(C)O IVDFJHOHABJVEH-UHFFFAOYSA-N 0.000 description 2
- 239000003505 polymerization initiator Substances 0.000 description 2
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 2
- 239000011342 resin composition Substances 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 2
- DNIAPMSPPWPWGF-VKHMYHEASA-N (+)-propylene glycol Chemical compound C[C@H](O)CO DNIAPMSPPWPWGF-VKHMYHEASA-N 0.000 description 1
- JNYAEWCLZODPBN-KVTDHHQDSA-N (2r,3r,4r)-2-[(1r)-1,2-dihydroxyethyl]oxolane-3,4-diol Chemical compound OC[C@@H](O)[C@H]1OC[C@@H](O)[C@H]1O JNYAEWCLZODPBN-KVTDHHQDSA-N 0.000 description 1
- JNYAEWCLZODPBN-JGWLITMVSA-N (2r,3r,4s)-2-[(1r)-1,2-dihydroxyethyl]oxolane-3,4-diol Chemical compound OC[C@@H](O)[C@H]1OC[C@H](O)[C@H]1O JNYAEWCLZODPBN-JGWLITMVSA-N 0.000 description 1
- MFEWNFVBWPABCX-UHFFFAOYSA-N 1,1,2,2-tetraphenylethane-1,2-diol Chemical compound C=1C=CC=CC=1C(C(O)(C=1C=CC=CC=1)C=1C=CC=CC=1)(O)C1=CC=CC=C1 MFEWNFVBWPABCX-UHFFFAOYSA-N 0.000 description 1
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- KOMNUTZXSVSERR-UHFFFAOYSA-N 1,3,5-tris(prop-2-enyl)-1,3,5-triazinane-2,4,6-trione Chemical compound C=CCN1C(=O)N(CC=C)C(=O)N(CC=C)C1=O KOMNUTZXSVSERR-UHFFFAOYSA-N 0.000 description 1
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- ALVZNPYWJMLXKV-UHFFFAOYSA-N 1,9-Nonanediol Chemical compound OCCCCCCCCCO ALVZNPYWJMLXKV-UHFFFAOYSA-N 0.000 description 1
- PQUXFUBNSYCQAL-UHFFFAOYSA-N 1-(2,3-difluorophenyl)ethanone Chemical compound CC(=O)C1=CC=CC(F)=C1F PQUXFUBNSYCQAL-UHFFFAOYSA-N 0.000 description 1
- UWFRVQVNYNPBEF-UHFFFAOYSA-N 1-(2,4-dimethylphenyl)propan-1-one Chemical compound CCC(=O)C1=CC=C(C)C=C1C UWFRVQVNYNPBEF-UHFFFAOYSA-N 0.000 description 1
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- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 description 1
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- KFNAHVKJFHDCSK-UHFFFAOYSA-N 2-[2-(4,5-dihydro-1,3-oxazol-2-yl)ethyl]-4,5-dihydro-1,3-oxazole Chemical compound N=1CCOC=1CCC1=NCCO1 KFNAHVKJFHDCSK-UHFFFAOYSA-N 0.000 description 1
- 125000000954 2-hydroxyethyl group Chemical group [H]C([*])([H])C([H])([H])O[H] 0.000 description 1
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- PUEFXLJYTSRTGI-UHFFFAOYSA-N 4,4-dimethyl-1,3-dioxolan-2-one Chemical compound CC1(C)COC(=O)O1 PUEFXLJYTSRTGI-UHFFFAOYSA-N 0.000 description 1
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- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
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Description
【０００１】
【発明の属する技術分野】
本発明は、吸水性樹脂、その製造方法および吸収性物品に関する。特に、血液ゲル吸収量に優れた吸水性樹脂、その製造方法およびそれを用いた吸収性物品に関する。
【０００２】
【従来の技術】
近年、体液を吸収させることを目的とし、紙おむつ、生理用ナプキンなどの衛生材料の構成材料の一つとして吸水性樹脂が幅広く利用されている。
上記の吸水性樹脂としては、例えば、ポリアクリル酸部分中和物架橋体、澱粉−アクリロニトリルグラフト重合体の加水分解物、澱粉−アクリル酸グラフト重合体の中和物、酢酸ビニル−アクリル酸エステル共重合体のケン化物、アクリロニトリル共重合体もしくはアクリルアミド共重合体の加水分解物またはこれらの架橋体、カチオン性モノマーの架橋体などが知られている。
【０００３】
被吸収液が血液などの場合には、血液吸収時に血液成分が個々の吸水性樹脂粒子を包囲し吸収を妨げるために吸水性樹脂の吸引量が低下する等の特別の事情があるため、尿に対する吸引量が高い吸水性樹脂であっても、血液に対する吸引量も高いとは限らない。
このような事情に鑑み、吸水性樹脂の血液吸収特性を改良する試みとして、種々の提案がなされている。例えば、吸水性樹脂の血液に対する吸収力改善を目的として、食塩やポリエチレングリコールのような化合物を吸水性樹脂に添加することが提案されている（特開昭５８−５０１１０７号公報、特開昭５４−７０６９４号公報）。また、高吸水性繊維を不均一にすることにより衛生材料用不織布の吸血率を向上させようとする試み（特開平６−２０７３５８号公報）や、上層と下層をそれぞれ粒度の異なる吸水性樹脂で構成した積層体（実開平６−５８９５２号公報）が提案されている。確かにこれらの構成とすることにより血液吸収特性は若干改善されるものの、未だ実用上不十分なものであった。
【０００４】
これを解決するものとして、国際公開９６−２８５１５号公報では、羊血に対する血液面積率という新規なパラメータを導入し、この血液面積率の高い吸血液性樹脂組成物は優れた血液吸収特性を示すこと、また吸水性樹脂の表面を高架橋することにより血液面積率が高い吸血液性樹脂組成物が得られることが開示されている。
【０００５】
【発明が解決しようとする課題】
国際公開９６−２８５１５号公報に開示された技術によると、確かに血液吸収特性はかなり改善されるものの、吸水性樹脂が血液を二度以上に分けて少量ずつ吸収した場合には、その合計で吸収できる血液の量は一気に吸収する場合と比べて少なくなってしまうという問題があることがわかった。つまり、吸水性樹脂がいったん血液を吸収してゲル（血液ゲル）となってしまうと、もはや本来吸収可能であったはずの量は吸収できないのである。例えば、一気に血液を吸収すれば１０ｇの血液を吸収可能な吸水性樹脂であっても、まず３ｇの血液を吸収してからしばらく時間をおいて血液ゲルとなってしまった後には、さらに７ｇの血液を吸収することは不可能となるのである。そのため、血液吸収量が多い吸水性樹脂であっても血液ゲル吸収性が悪ければ、せっかくの血液吸収量が多いという特徴は十分に生かされず、結果として実用性に劣ったものとなってしまう。
【０００６】
したがって、本発明の課題は、血液ゲル吸収性に優れた吸水性樹脂、その製造方法およびそれを用いた吸収性物品を提供することにある。
【０００７】
【課題を解決するための手段】
上記課題を解決するため、本発明は、以下の構成をとる。
(1) 表面架橋された粉末状の吸水性樹脂であって、前記表面架橋が吸水性樹脂１００重量部に対してエチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、グリセリンおよびジグリセリンから選ばれる少なくとも１種の多価アルコールである表面架橋剤を０．５〜１０重量部用いることでなされており、平均粒径が１００〜８００μｍであり、粒度分布の正規標準偏差が１３０μｍ以上である、ことを特徴とする、吸水性樹脂。
ただし、吸水性樹脂は、アクリル酸の３０〜９０モル％が塩基性物質で中和されている水溶性不飽和単量体を重合させることにより得られるものであり、平均粒径は、ＪＩＳ標準ふるい（目開き８５０μｍ、７１０μｍ、６００μｍ、５００μｍ、４２５μｍ、３５５μｍ、３００μｍ、２５０μｍ、１８０μｍ、１５０μｍ、１００μｍ、７５μｍ、４５μｍ）を用いて試料樹脂をふるい分級した後、残留百分率Ｒを正規確率紙にプロットし、Ｒ＝５０質量％に相当する粒径とする（以下同様）。
正規標準偏差は下記式で規定するものである（以下同様）。
【数２】
【０００９】
(2) 前記(1) に記載の、平均粒径が１００〜８００μｍの粉末状の吸水性樹脂の製造方法であって、吸水性樹脂１００重量部に対してエチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、グリセリンおよびジグリセリンから選ばれる少なくとも１種の多価アルコールである表面架橋剤を０．５〜１０重量部用いることで表面架橋されている、互いに平均粒径の異なる二種以上の表面架橋された粉末状の吸水性樹脂を混合する工程を含む、ことを特徴とする、吸水性樹脂の製造方法。
【００１１】
(3) 前記(1)に記載の吸水性樹脂を坪量２０〜１００００ｇ／ｍ２で用いた、吸収性物品。
【００１２】
【発明の実施の形態】
被吸収液が人工尿の場合には二度以上に分けて吸液した場合と一度に吸液した場合とで吸液量にほとんど違いがなかったことから、血液ゲル吸収量の問題は、血液等に特有の問題であると考えられる。本発明者らは、血液の方が人工尿よりもゲルブロッキングを起こしやすいことも考え合わせて、人工尿と血液との一番大きな違いは、血液は液体成分の他に固体成分である血球等を含んでいることであると考え、血球等が血液ゲル吸収性を阻害する原因であると推測した。さらに検討を進め、血球の内部は水分であることから、血液が吸水性樹脂に吸収される際に血球中の水分も吸水性樹脂に吸収され、血球の表面膜が吸水性樹脂表面に密着した状態で吸水性樹脂がゲル化し、血球の表面膜によって吸水性樹脂と新たな液体（血液）との接触が阻害されるのではないかと考えた。
【００１３】
通常の製法によって得られた吸水性樹脂の粒度分布はごく普通の山型で、平均粒径付近の粒径のものが最も多く、極めて粒径の小さいものや極めて粒径の大きいものの割合は少なくなっている。従来技術では、粒度分布をシャープにすることを課題としているものも多く（特開平２−１９１６０４号公報、特開平３−２２７３０１号公報、特表平６−５０７５６４号公報等）、その場合にはこの傾向は特に顕著となる。一般に同一組成の吸水性樹脂においては血液吸収速度と粒径は良く相関していることが知られており、粒径が小さいものほど血液吸収速度が大きい。したがって、吸水性樹脂が血液に接触したときには粒径の小さい吸水性樹脂ほど多量の吸液を行う。通常の吸水性樹脂では極めて粒径の小さいものの割合が少ないため、初めて血液に接触したときにそれら極めて粒径の小さい吸水性樹脂だけでは絶対的な吸液量が足りず平均粒径付近の粒径の吸水性樹脂もかなりの吸液を行う。つまり、はじめて血液に接触したときに大半の吸水性樹脂がかなりの吸液を行うために、大半の吸水性樹脂の表面に血球が密着してしまう。言い換えれば、表面に血球の密着のない吸水性樹脂がほとんど残らないので、次に再び血液に接触したときには、吸液を十分に行うことができないこととなる。本発明者らは、血液ゲル吸収性を高めるためには、吸水性樹脂が初めて血液に接触したときには吸液をほとんど行わず、次に再び血液に接触したときに初めて吸液を行う吸水性樹脂の割合を多くすることが有効であると考え、本発明に到達したものである。
【００１４】
すなわち、本発明では、吸水性樹脂の血液吸収速度の分布に十分な拡がりをもたせることで、初めて血液に接触したときには血液吸収速度の大きい（平均粒径の小さい）側の吸水性樹脂だけで吸液を行い、次に再び血液と接触するときに備えて多くの吸水性樹脂、つまり血液吸収速度の小さい（平均粒径の大きい）側の吸水性樹脂を表面に血球の密着のない状態で残しておくというものである。
【００１５】
すなわち、本発明では吸水性樹脂の製造方法として、互いに血液吸収速度の異なる二種以上の吸水性樹脂を混合する方法を提供する。血液吸収速度とは、後述の実施例において定義されるものであり、吸水性樹脂が所定時間（１分間）で吸水性樹脂が血液を吸収する量を定量するものである。混合する吸水性樹脂間の血液吸収速度の差（３種以上の吸水性樹脂を混合する場合には、血液吸収速度の順に並べて隣り合うもの同士の差をいう）の中で少なくとも一つの差が０．０５ｇ／ｇ／秒以上であることが好ましく、より好ましくは０．１０ｇ／ｇ／秒以上、さらに好ましくは０．１５ｇ／ｇ／秒以上である。混合する吸水性樹脂のうち、最も血液吸収速度の大きいものの血液吸収速度は０．１０〜０．３３ｇ／ｇ／秒の範囲内にあることが好ましく、０．１５〜０．２５ｇ／ｇ／秒の範囲内にあることがより好ましい。また、最も血液吸収速度の小さいものの血液吸収速度は０．０１〜０．１０ｇ／ｇ／秒の範囲内にあることが好ましく、０．０３〜０．０７ｇ／ｇ／秒の範囲内にあることがより好ましい。混合する吸水性樹脂は同じ組成のものであっても、互いに異なる組成のものであってもかまわないが、同じ組成の場合には血液吸収速度と粒径との相関が良いので、粒径を制御することによって血液吸収速度を制御できるという利点がある。
【００１６】
したがって、本発明では吸水性樹脂の製造方法として、互いに平均粒径の異なる二種以上の粉末状の吸水性樹脂を混合する方法をも提供する。混合する吸水性樹脂間の平均粒径の差（３種以上の吸水性樹脂を混合する場合には、平均粒径の順に並べて隣り合うもの同士の差をいう）の中で少なくとも一つの差が１００μｍ以上であることが好ましく、より好ましくは３００μｍ以上、さらに好ましくは５００μｍである。混合する吸水性樹脂のうち、最も平均粒径の大きいものの平均粒径は３００〜１０００μｍの範囲内にあることが好ましく、４００〜８００μｍの範囲内にあることがより好ましい。また、最も平均粒径の小さいものの平均粒径は１〜３００μｍの範囲内にあることが好ましく、１０〜１００μｍの範囲内にあることがより好ましい。
【００１７】
互いに平均粒径の異なる二種以上の粉末状の吸水性樹脂を得るには、粉末状の吸水性樹脂を複数の粒度範囲に分級するのが簡便である。吸水性樹脂を分級した後、分級によって得られた互いに重複しない粒度範囲の二種以上の吸水性樹脂を混合することで、混合する吸水性樹脂の互いの組成が互いに同じとなるので好ましい。特に、分級によって得られた複数の粒度範囲の吸水性樹脂のうち、互いに隣接する粒度範囲の吸水性樹脂同士を混合するよりも、１つ以上間のあいた互いに隣接しない吸水性樹脂同士を混合する方が、得られる吸水性樹脂の粒径の拡がりが広くなるので好ましい。例えば、１５０〜３００μｍ、３００〜６００μｍ、６００〜８５０μｍの３種の粒度範囲の吸水性樹脂を分級によって得た場合には、１５０〜３００μｍの吸水性樹脂と３００〜６００μｍの吸水性樹脂とは、「３００μｍ」で粒度範囲が隣接し、３００〜６００μｍの吸水性樹脂と６００〜８５０μｍの吸水性樹脂とは、「６００μｍ」で粒度範囲が隣接するので、真ん中の３００〜６００μｍの吸水性樹脂を用いず、両端の１５０〜３００μｍの吸水性樹脂と６００〜８５０μｍの吸水性樹脂を混合することが好ましい。
【００１８】
本発明の効果を十分に発揮するためには、混合する二種以上の吸水性樹脂の混合比率をなるべく等量ずつとすることが好ましく、具体的には最も量の多いものと少ないものとの重量比が２倍以内、好ましくは１．５倍以内、より好ましくは１．２倍以内であることが好ましい。
上記のような製法によって、本発明の、粒度分布の正規標準偏差が１３０μｍ以上の粉末状の吸水性樹脂を得ることができる。吸水性樹脂の粒度分布の正規標準偏差は１７０μｍ以上であることが好ましく、２１０μｍ以上であることがより好ましい。通常の製法によって得られた吸水性樹脂では正規標準偏差が高々１１５μｍ程度と考えられる。正規標準偏差が１３０μｍ以上のなるような粒度分布の形態としては、(1) ピークを２つ以上有するもの、(2) ピークは１つであるが、極めてブロードであるか台形状であるもの、が例として挙げられる。本発明の効果を十分に発揮するためには、(2) より(1) が好ましく、さらに(1) においてピーク間距離（３つ以上のピークを有する場合には、隣り合うピーク間の距離をいう）の少なくとも一つが、１００μｍ以上であることが好ましく、３００μｍ以上であることがより好ましい。ピーク間距離が短いとピークを２つ以上有する効果が低く、初めて血液に接触したときにほとんど全ての吸水性樹脂が吸液を行うことになり、次に再び血液に接触したときに吸液を行うことのできる吸水性樹脂の割合が減少する。ピークのうち最も粒径の小さい側のピークは１〜３００μｍの範囲内にあることが好ましく、１０〜２００μｍの範囲内にあることがより好ましい。また、最も粒径の大きい側のピークは３００〜１０００μｍの範囲内にあることが好ましく、４００〜８００μｍの範囲内にあることがより好ましい。(1) の形態の粒度分布は、例えば互いに隣接しない粒度範囲の吸水性樹脂を混合することで容易に得ることができる。(2) の形態の粒度分布は、例えば互いに隣接する粒度分布の吸水性樹脂をなるべく等量ずつ混合することで容易に得ることができる。
【００１９】
本発明の吸水性樹脂の平均粒径としては１００〜８００μｍの範囲内にあることが好ましく、３００〜６００μｍの範囲内であることがより好ましい。
本発明の吸水性樹脂は、血液ゲル吸収量が高いことが特徴であり、２ｇ／ｇ以上を容易に達成することができる。血液ゲル吸収量とは、後述の実施例において定義されるものであり、吸水性樹脂が血液を吸収してゲルとなった状態での血液吸収量を定量するものである。血液ゲル吸収量が高いほど、吸水性樹脂が血液を二度以上にわけて少量ずつ吸収した場合でも合計で吸収できる血液の量が多いことを表わす。血液ゲル吸収量は好ましくは２．５ｇ／ｇ以上、より好ましくは３ｇ／ｇ以上である。
【００２０】
本発明の吸水性樹脂において、血液ゲル吸収量が高いという特徴を十分に生かすためには、血液吸引量が高いことが好ましい。血液吸引量とは、後述の実施例において定義されるものであり、吸水性樹脂が血液を引く力を定量するものである。血液吸引量は５ｇ／ｇ以上であることが好ましく、より好ましくは１０ｇ／ｇ以上である。血液吸引量の高い吸水性樹脂を得るためには、原料となる混合する吸水性樹脂のそれぞれの血液吸引量が高いことが好ましく、５ｇ／ｇ以上であることが好ましく、より好ましくは１０ｇ／ｇ以上である。
【００２１】
本発明の吸水性樹脂の吸水倍率は、生理食塩水中のティーバッグ法による値で、２０〜６０ｇ／ｇ程度有することが好ましい。未架橋成分、いわゆる水可溶成分の割合は２０重量％以下が好ましく、より好ましくは１０重量％以下、さらに少ないほど好ましい。
本発明において用いられる吸水性樹脂としては、水を吸収して体積膨張を起こすものであれば特に制限はないが、一般に水溶性不飽和単量体を重合させることにより得られる。これらの水溶性不飽和単量体の例としては、（メタ）アクリル酸、（無水）マレイン酸、フマル酸、クロトン酸、イタコン酸、２−（メタ）アクリロイルエタンスルホン酸、２−（メタ）アクリロイルプロパンスルホン酸、２−（メタ）アクリルアミド−２−メチルプロパンスルホン酸、ビニルスルホン酸、スチレンスルホン酸等のアニオン性単量体やその塩；（メタ）アクリルアミド、Ｎ−置換（メタ）アクリルアミド、２−ヒドロキシエチル（メタ）アクリレート、２−ヒドロキシプロピル（メタ）アクリレート、メトキシポリエチレングリコール（メタ）アクリレート、ポリエチレングリコール（メタ）アクリレート等のノニオン性親水基含有単量体、Ｎ，Ｎ−ジメチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ−ジメチルアミノプロピル（メタ）アクリレート、Ｎ，Ｎ−ジメチルアミノプロピル（メタ）アクリルアミド等のアミノ基含有不飽和単量体やそれらの４級化物等を具体的に挙げることができる。また、得られる重合体の親水性を極度に阻害しない程度の量で、例えば、メチル（メタ）アクリレート、エチル（メタ）アクリレート、ブチル（メタ）アクリレート等のアクリル酸エステル類や酢酸ビニル、プロピオン酸ビニル等の疎水性単量体を使用してもよい。単量体成分としてはこれらのうちから１種または２種以上を選択して用いることができるが、最終的に得られる吸水性物品の吸水諸特性を考えると（メタ）アクリル酸（塩）、２−（メタ）アクリロイルエタンスルホン酸（塩）、２−（メタ）アクリルアミド−２−メチルプロパンスルホン酸（塩）、（メタ）アクリルアミド、メトキシポリエチレングリコール（メタ）アクリレート、Ｎ，Ｎ−ジメチルアミノエチル（メタ）アクリレートまたはその４級化物からなる群から選ばれる１種以上のものが好ましく、（メタ）アクリル酸（塩）を必須成分として含むものがさらに好ましい。この場合（メタ）アクリル酸の３０〜９０モル％が塩基性物質で中和されているものが最も好ましい。
【００２２】
また、吸水性樹脂は、架橋剤を使用せずに得られる自己架橋型のものでも、重合性不飽和基および／または反応性官能基を有する架橋剤を、得られる吸水性樹脂の諸特性が所望の基準に達する範囲で用いて得られるものでもよい。この場合、吸水性樹脂内部の架橋に用いられる内部架橋剤の例としては、例えばＮ，Ｎ’−メチレンビス（メタ）アクリルアミド、（ポリ）エチレングリコール（メタ）アクリレート、グリセリントリ（メタ）アクリレート、トリメチロールプロパントリ（メタ）アクリレート、トリアリルアミン、トリアリルシアヌレート、トリアリルイソシアヌレート、グリシジル（メタ）アクリレート、（ポリ）エチレングリコール、ジエチレングリコール、（ポリ）グリセリン、プロピレングリコール、ジエタノールアミン、トリメチロールプロパン、ペンタエリスリトール、（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）グリセロール（ポリ）グリシジルエーテル、エピクロルヒドリン、エチレンジアミン、ポリエチレンイミン、（ポリ）塩化アルミニウム、硫酸アルミニウム、塩化カルシウム、硫酸マグネシウム等を具体的に挙げることができる。これらのうち反応性を考慮して、１種または２種以上を用いることができる。
【００２３】
吸水性樹脂の表面近傍を架橋処理することにより、吸水性樹脂の血液吸引量および血液吸収量を高めることができる。表面架橋剤としては、吸水性樹脂の表面の官能基と反応できる２個以上の官能基を有するもので、生理用ナプキン等の吸収性物品に使用した場合安全性の高いものが好ましく、例えば、エチレングリコール、ジエチレングリコール、トリエチレングリコール、ポリエチレングリコール、プロピレングリコール、ポリプロピレングリコール、トリメチレングリコール、１，３−プロパンジオール、１，４−ブタンジオール、１，５−ペンタンジオール、１，６−ヘキサンジオール、１，７−ヘプタンジオール、１，８−オクタンジオール、１，９−ノナンジオール、ピナコール、ヒドロベンゾイン、ベンズピナコール、シクロペンタン−１，２−ジオール、シクロヘキサン−１，４−ジオール、ペンタエリスリトール、グリセリン、ジグリセリン、ポリグリセリン、ジエタノールアミン、トリエタノールアミン、ポリオキシプロピレン、オキシエチレン−オキシプロピレンブロックポリマー、ソルビット、ソルビタン、ソルビタン脂肪酸エステル、ポリオキシエチレンソルビタン脂肪酸エステル、トリメチロールプロパン、ペンタエリトリット、ポリビニルアルコール、グルコース、マンニット、マンニタン、ショ糖、ブドウ糖等の多価アルコール；エチレンカーボネート、プロピレンカーボネート、４，５−ジメチル−１，３−ジオキソラン−２−オン、４，４−ジメチル−１，３−ジオキソラン−２−オン、４−エチル−１，３−ジオキソラン−２−オン、４−ヒドロキシメチル−１，３−ジオキソラン−２−オン、１，３−ジオキサン−２−オン、４−メチル−１，３−ジオキサン−２−オン、４，６−ジメチル−１，３−ジオキサン−２−オン等のアルキレンカーボネート；エチレンジアミン、ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ペンタエチレンヘキサミン、ポリエチレンイミン等の多価アミン；２，４−トリレンジイソシアネート、ヘキサメチレンジイソシアネート等の多価イソシアネート；１，２−エチレンビスオキサゾリン等の多価オキサゾリン；２，２−ビスヒドロキシメチルブタノール−トリス［３−（１−アジリジル）プロピオネート］、１，６−ヘキサメチレンジエチレンウレア、ジフェニルメタン−ビス−４，４’−Ｎ，Ｎ’−ジエチレンウレア等の多価アジリジン等が挙げられる。表面架橋剤としては、これらのうちの１種または２種以上を用いることができる。中でも、得られる吸水性樹脂の血液吸引量および血液吸収量の観点から多価アルコールおよびアルキレンカーボネートが好ましく、エチレングリコール、ジエチレングリコール、トリエチレングリコール、ポリエチレングリコール、プロピレングリコール、グリセリン、ジグリセリン、ポリグリセリン、エチレンカーボネート、プロピレンカーボネートが好ましく、グリセリンが最も好ましい。
【００２４】
表面架橋剤の使用量は特に限定されないが、吸水性樹脂１００重量部に対して０．５〜１０重量部の範囲が好ましく、さらに好ましくは２〜５重量部の範囲である。使用量が０．５重量部未満では、たとえ長時間加熱しても得られる吸水性樹脂の血液吸引量および血液吸収量が上がりにくい。一方、使用量が１０重量部を越えると、使用量の増加に相当する効果を得ることは困難であり、さらに未反応物が残存し、そのため種々のトラブルの原因となるばかりでなく不経済である。
【００２５】
前記吸水性樹脂に表面架橋処理を施すには、通常、吸水性樹脂と表面架橋剤を均一に混合後、造粒したものを加熱処理する。
吸水性樹脂と表面架橋剤の混合を均一にするには、吸水性樹脂１００重量部に対し、水０〜５０重量部および親水性有機溶媒０〜６０重量部を用いてもよい。
親水性有機溶媒としては、メタノール、エタノール、ｎ−プロパノール、イソプロパノール、ｎ−ブタノール、イソブタノール、ｓｅｃ−ブタノールおよびｔ−ブタノールのような低級アルコール類、アセトン、メチルエチルケトン、メチルイソブチルケトンのようなエーテル類、ジオキサン、テトラヒドロフランおよびジエチルエーテルのようなエーテル類、Ｎ，Ｎ−ジメチルホルムアミドおよびＮ，Ｎ−ジエチルホルムアミドのようなアミド類およびジメチルスルホキシドのようなスルホキシド類が挙げられる。
【００２６】
混合方法は特に制限されず、通常の混合機を用いることができる。
加熱処理は、表面架橋剤として多価アルコールまたはアルキレンカーボネートを使用する場合、被加熱物の温度および加熱処理時間が下記式（１）に示される条件下で行うのが好ましい。
ｌｏｇ（ｔ）≧１５．７×１０3（１／Ｔ）−２４．４ （１）
（式中、ｔは加熱処理時間（秒）であり、Ｔは被加熱物の絶対温度（Ｋ）である。）
式（１）を満足しない条件で加熱処理を行うと血液吸引量および血液吸収量の劣ったものとなる。さらに、下記式（２）に示される条件下で行うのが好ましい。
【００２７】
１５．７×１０3（１／Ｔ）−２３≧
ｌｏｇ（ｔ）≧１５．７×１０3（１／Ｔ）−２４．４ （２）
（式中、ｔは加熱処理時間（秒）であり、Ｔは被加熱物の絶対温度（Ｋ）である。）
式（２）を満足しない条件で加熱処理を行うと、長時間費やしたことに相当する効果を得ることは困難であり不経済である。
【００２８】
表面架橋剤が多価アルコールまたはアルキレンカーボネートである場合、具体的な被加熱物の温度および加熱処理時間としては、１７０℃で１８時間以上７０時間以下〜２５０℃で５分以上１８分以下が好ましく、１８０℃で８時間以上３０時間以下〜２１０℃で１時間以上３時間以下がより好ましい。被加熱物の温度が１７０℃未満であると、血液吸引量および血液吸収量の高いものを得るために非常に長い時間がかかり経済的でない。一方、被加熱物の温度が２５０℃を越えるものであると、使用される吸水性樹脂の種類によっては熱劣化を起こす危険性がある。
【００２９】
本発明において加熱方法は、特に制限されるものではなく、通常の乾燥機や加熱炉、例えば溝型攪拌乾燥機、回転乾燥機、流動層乾燥機、気流乾燥機、赤外線乾燥機、誘電加熱等を用いることができる。この加熱処理の際の剪断力や破砕力はできるだけ小さい方が、血液吸引量や血液吸収量の優れたものを得るために好ましく、上記の中で流動層乾燥機、気流乾燥機が好ましい。
【００３０】
本発明では、表面架橋を行った吸水性樹脂を分級してもよいし、吸水性樹脂に分級した後でそれぞれに表面架橋を行っても良い。
本発明の吸収性物品は、本発明の吸水性樹脂を親水性繊維等の必要な部材と組み合わせて構成したものである。坪量は２０〜１００００ｇ／ｍ2の範囲が一般的であり、１００〜１０００ｇ／ｍ2の範囲が好ましく、２００〜６００ｇ／ｍ2の範囲がより好ましい。
【００３１】
本発明の吸収性物品に用いられる親水性繊維としては、公知のものがいずれも使用できる。例えば、粉砕された木材パルプ、コットンリンターや架橋セルロース繊維、レーヨン、綿、羊毛、アセテート、ビニロン等を用いることができる。
中でも、粉砕された木材パルプのエアレイド・パッドの形のものが好ましい。
本発明の吸収性物品は、拡散層、脚部弾性部材、腰部弾性部材、テープなど公知の多数の部材を具備していてもよい。
【００３２】
本発明の吸収性物品は、上述したように血液に対して優れた吸収特性を示すものであるが、その他、血液と同様にタンパク質成分を含む水、例えば、牛乳、母乳、おりもの等に対しても優れた吸収特性を示す。また、従来の吸水性樹脂と同様の尿、海水、セメント水、土壌水、肥料含有水、雨水、排水等に対しても優れた吸収特性を示す。具体的な用途として、生理用ナプキン、タンポン、医療用血液吸収性物品、創傷保護材、創傷治癒材、手術用廃液処理剤等の血液吸収特性の要求される用途の他、使い捨ておむつや失禁パット等の衛生材料、土木、農園芸等の各種産業分野においても好適に用いられる。さらに、本発明の吸水性樹脂または吸収性物品に消臭剤、香料、薬剤、植物生育助剤、殺菌剤、発泡剤、顔料、染料、親水性短繊維、肥料等を介在させることにより、得られる吸水性樹脂または吸収性物品に新たな機能を付与することもできる。
【００３３】
【実施例】
以下、実施例および比較例により、本発明をさらに詳細に説明するが、本発明はこれらにより何ら限定されるものではない。
なお、実施例中で「部」とは特にことわりがない限り「重量部」を表すものとする。
【００３４】
吸水性樹脂の諸性能は以下の方法により測定した。
（ａ）血液吸引量
内径９５ｍｍのシャーレ中の羊血（緬羊脱繊維血液；日本バイオテスト研究所製、以下同じ）２０ｍｌに浸した１６枚重ねのトイレットペーパー（５５ｍｍ×７５ｍｍ）上に試料樹脂約１ｇを加え、５分間吸液させた後、膨潤ゲルを採取してその重量を測定した。吸液後の膨潤ゲルの重量を元の試料樹脂の重量で除して、試料樹脂の血液吸引量（ｇ／ｇ）を算出した。
（ｂ）血液吸収量
内径６０ｍｍのシャーレ中に試料樹脂１ｇをできるだけ均一にまき、その上に羊血５ｇを滴下し、血液を吸ったゲルとする。ほとんどの吸水性樹脂はこの状態で均一なゲルにはならない。
【００３５】
次に、５分放置後、キッチンタオル（１０枚重ね）をそのゲルの上に置き、その上に重り（荷重0.7psi=49g/cm2）を乗せ、１分後のキッチンタオルの重量を測定し、その重量変化を、滴下した羊血から引いた値を血液吸収量とした。
（ｃ）血液ゲル吸収量
内径６０ｍｍのシャーレ中に試料樹脂１ｇをできるだけ均一にまき、その上に羊血５ｇを滴下し、血液を吸ったゲルとする。
【００３６】
６０分放置後、上記血液を吸ったゲルに羊血を５ｇ滴下し、５分放置後、キッチンタオル（１０枚重ね）を前記ゲルの上に置き、その上に重り（荷重0.7psi=49g/cm2）を乗せ、１分後のキッチンタオルの重量を測定し、その重量変化を、滴下した羊血から引いた値を血液ゲル吸収量とした。
（ｄ）血液戻り量
吸収性物品の中心部に羊血約１５ｇを注射器で滴下し、約５分間経過後、吸収性物品の表面を手で触って戻り量を評価し、それを血液戻り量▲１▼とした。さらに、１時間経過後、羊血１５ｇを注射器で滴下し、約５分経過後、吸収性物品の表面を手で触って戻り量を評価し、それを血液戻り量▲２▼とした。
（ｅ）血液吸収速度
内径９５ｍｍのシャーレ中に羊血２０ｍｌに浸した１６枚重ねのトイレットペーパー（５５ｍｍ×７５ｍｍ）上に試料樹脂約１ｇを加え、１分間吸液させた後、膨潤ゲルを採取してその重量を測定した。以下の式に従い血液吸収速度を算出した。
【００３７】
【数１】
（ｆ）平均粒径・粒度分布
平均粒径は、ＪＩＳ標準ふるい（目開き８５０μｍ、７１０μｍ、６００μｍ、５００μｍ、４２５μｍ、３５５μｍ、３００μｍ、２５０μｍ、１８０μｍ、１５０μｍ、１００μｍ、７５μｍ、４５μｍ）を用いて試料樹脂をふるい分級した後、残留百分率Ｒを正規確率紙にプロットし、Ｒ＝５０％に相当する粒径を平均粒径とした。
【００３９】
粒度分布としては、その指標として下記の式で表わされる正規標準偏差値を用いた。ここでは、正規標準偏差値が大きいほど粒度分布が広いことを意味する。
【００４０】
【数２】
（Ｘ0はＲ＝５０％、Ｘ1はＲ＝８４．１％、Ｘ2はＲ＝１５．９％のときのそれぞれの粒径）
［実施例１］
カルボキシル基を有する吸水性樹脂の製造に際して、単量体成分としてのアクリル酸ナトリウム（中和率７５モル％）の３７重量％水溶液４４００部に、内部架橋剤としてのトリメチロールプロパントリアクリレート２．７２部を溶解させて反応液とした。次に、この反応液を窒素ガス雰囲気下で３０分間脱気した。
【００４２】
次いで、シグマ型羽根を２本有するジャケット付きステンレス製双腕型ニーダーに蓋を付けた反応器に上記反応液を供給し、反応液を３０℃に保ちながら上記反応器内を窒素ガス置換した。続いて、反応液を攪拌しながら、重合開始剤としての過硫酸ナトリウム１．１部、および重合開始剤の分解を促進する還元剤としての亜硫酸ナトリウム１．１部を添加したところ、およそ１分後に重合が開始した。そして、３０℃〜８０℃で重合を行い、重合を開始して４０分後に含水ゲル状重合体を取り出した。
【００４３】
得られた含水ゲル状重合体を金網上に広げ、１５０℃で２時間熱風乾燥した。
次いで、乾燥物をハンマーミルを用いて粉砕し、さらに目開き８５０μｍの金網で分級することにより平均粒径４００μｍの吸水性樹脂（１）を得た。
次いで、得られた吸水性樹脂（１）１００部に対し、グリセリン０．５部、水２部およびイソプロピルアルコール０．５部を含有する水性液をレディゲミキサー（Ｍ５Ｒ、レディゲ社製）で約３０分間混合し、得られた吸水性樹脂混合物（１）を乾燥機の中に入れ２２０℃で２時間の加熱処理をし、吸水性樹脂（２）を得た。吸水性樹脂（２）の血液吸引量は１２．５ｇ／ｇであった。
【００４４】
吸水性樹脂（２）を目開き８５０μｍ、６００μｍ、３００μｍ、１５０μｍで分級し、８５０μｍ〜６００μｍを吸水性樹脂（２Ａ）、６００μｍ〜３００μｍを吸水性樹脂（２Ｂ）、３００μｍ〜１５０μｍを吸水性樹脂（２Ｃ）、１５０μｍ以下を吸水性樹脂（２Ｄ）とした。吸水性樹脂（２Ａ）、（２Ｂ）、（２Ｃ）、（２Ｄ）の血液吸収速度はそれぞれ、０．０４ｇ／ｇ／秒、０．０９ｇ／ｇ／秒、０．１３ｇ／ｇ／秒、０．１８ｇ／ｇ／秒であった。また、吸水性樹脂（２Ａ）、（２Ｂ）、（２Ｃ）、（２Ｄ）の血液吸引量はそれぞれ、１３．１ｇ／ｇ、１２．８ｇ／ｇ、１２．２ｇ／ｇ、１２．０ｇ／ｇであり、平均粒径はそれぞれ、７１０μｍ、４２０μｍ、２４０μｍ、９２μｍであった。
【００４５】
吸水性樹脂（２Ａ）５０部と吸水性樹脂（２Ｄ）５０部とを混合し、本発明の吸水性樹脂（ａ）を得た。吸水性樹脂（ａ）の血液吸引量は１２．６ｇ／ｇであった。吸水性樹脂（ａ）は平均粒径が４１０μｍで、７００μｍと１００μｍに２つのピークを有していた。
［実施例２］
実施例１で得た吸水性樹脂（２Ａ）５０部と吸水性樹脂（２Ｃ）５０部とを混合し、本発明の吸水性樹脂（ｂ）を得た。吸水性樹脂（ｂ）の血液吸引量は１２．４ｇ／ｇであった。吸水性樹脂（ｂ）は平均粒径が４８０μｍで、７００μｍと２５０μｍに２つのピークを有していた。
［実施例３］
実施例１で得た吸水性樹脂（２Ｂ）５０部と吸水性樹脂（２Ｄ）５０部とを混合し、本発明の吸水性樹脂（ｃ）を得た。吸水性樹脂（ｃ）の血液吸引量は１２．３ｇ／ｇであった。吸水性樹脂（ｃ）は平均粒径が２５０μｍで、４１０μｍと１００μｍに２つのピークを有していた。
［実施例４］
実施例１で得た吸水性樹脂（２Ａ）２５部と吸水性樹脂（２Ｂ）２５部と吸水性樹脂（２Ｃ）２５部と吸水性樹脂（２Ｄ）２５部とを混合し、本発明の吸水性樹脂（ｄ）を得た。吸水性樹脂（ｄ）の血液吸引量は１２．５ｇ／ｇであった。吸水性樹脂（ｄ）は平均粒径が３９０μｍで、粒度分布の形状は台形状であった。
［参考例１］
実施例１で得た吸水性樹脂（１）を目開き８５０μｍ、６００μｍ、３００μｍ、１５０μｍで分級し、８５０μｍ〜６００μｍを吸水性樹脂（１Ａ）、６００μｍ〜３００μｍを吸水性樹脂（１Ｂ）、３００μｍ〜１５０μｍを吸水性樹脂（１Ｃ）、１５０μｍ以下を吸水性樹脂（１Ｄ）とした。
【００４６】
得られた吸水性樹脂（１Ａ）１００部に対し、グリセリン０．２部、水１部およびイソプロピルアルコール０．５部を含有する水性液をレディゲミキサー（Ｍ５Ｒ、レディゲ社製）で約３０分間混合し、得られた吸水性樹脂混合物（１Ａ）を乾燥機の中に入れ２２０℃で２時間の加熱処理をし、吸水性樹脂（３Ａ）を得た。吸水性樹脂（３Ａ）の血液吸引量は１２．８ｇ／ｇ、血液吸収速度は０．０５ｇ／ｇ／秒、平均粒径は７３０μｍであった。
【００４７】
得られた吸水性樹脂（１Ｂ）１００部に対し、グリセリン０．４部、水２部およびイソプロピルアルコール０．５部を含有する水性液をレディゲミキサー（Ｍ５Ｒ、レディゲ社製）で約３０分間混合し、得られた吸水性樹脂混合物（１Ｂ）を乾燥機の中に入れ２２０℃で２時間の加熱処理をし、吸水性樹脂（３Ｂ）を得た。吸水性樹脂（３Ｂ）の血液吸引量は１２．５ｇ／ｇ、血液吸収速度は０．１１ｇ／ｇ／秒、平均粒径は４４０μｍであった。
【００４８】
得られた吸水性樹脂（１Ｃ）１００部に対し、グリセリン０．６部、水２部およびイソプロピルアルコール０．５部を含有する水性液をレディゲミキサー（Ｍ５Ｒ、レディゲ社製）で約３０分間混合し、得られた吸水性樹脂混合物（１Ｃ）を乾燥機の中に入れ２２０℃で２時間の加熱処理をし、吸水性樹脂（３Ｃ）を得た。吸水性樹脂（３Ｃ）の血液吸引量は１１．９ｇ／ｇ、血液吸収速度は０．１５ｇ／ｇ／秒、平均粒径は２８０μｍであった。
得られた吸水性樹脂（１Ｄ）１００部に対し、グリセリン１部、水４部およびイソプロピルアルコール１部を含有する水性液をレディゲミキサー（Ｍ５Ｒ、レディゲ社製）で約３０分間混合し、得られた吸水性樹脂混合物（１Ｄ）を乾燥機の中に入れ２２０℃で２時間の加熱処理をし、吸水性樹脂（３Ｄ）を得た。吸水性樹脂（３Ｄ）の血液吸引量は１２．７ｇ／ｇ、血液吸収速度は０．２０ｇ／ｇ／秒、平均粒径は１４０μｍであった。
【００４９】
吸水性樹脂（３Ａ）５０部と吸水性樹脂（３Ｄ）５０部とを混合し、本発明の吸水性樹脂（ｅ）を得た。吸水性樹脂（ｅ）の血液吸引量は１２．７ｇ／ｇであった。吸水性樹脂（ｅ）は平均粒径が４３０μｍで、７２０μｍと１５０μｍに２つのピークを有していた。
［実施例５］
実施例１で得た吸水性樹脂（３Ａ）５０部と吸水性樹脂（３Ｃ）５０部とを混合し、本発明の吸水性樹脂（ｆ）を得た。吸水性樹脂（ｆ）の血液吸引量は１２．４ｇ／ｇであった。吸水性樹脂（ｆ）は平均粒径が５００μｍで、７２０μｍと２９０μｍに２つのピークを有していた。
［実施例６］
実施例１で得た吸水性樹脂（３Ｂ）５０部と吸水性樹脂（３Ｄ）５０部とを混合し、本発明の吸水性樹脂（ｇ）を得た。吸水性樹脂（ｇ）の血液吸引量は１２．６ｇ／ｇであった。吸水性樹脂（ｇ）は平均粒径が３００μｍで、４３０μｍと１５０μｍに２つのピークを有していた。
［実施例７］
実施例１で得た吸水性樹脂（３Ａ）２５部と吸水性樹脂（３Ｂ）２５部と吸水性樹脂（３Ｃ）２５部と吸水性樹脂（３Ｄ）２５部とを混合し、本発明の吸水性樹脂（ｈ）を得た。吸水性樹脂（ｈ）の血液吸引量は１２．５ｇ／ｇであった。吸水性樹脂（ｈ）は平均粒径が４２０μｍで、粒度分布の形状は台形状であった。
［比較例１］
実施例１で得た吸水性樹脂（２）を比較用吸水性樹脂（ａ）とした。比較用吸水性樹脂（ａ）の粒度分布の形状は山状でピークは一つであった。
［比較例２］
参考例１で得た吸水性樹脂（３Ａ）を比較用吸水性樹脂（ｂ）とした。比較用吸水性樹脂（ｂ）の粒度分布の形状はシャープな山状でピークは一つであった。
［比較例３］
参考例１で得た吸水性樹脂（３Ｂ）を比較用吸水性樹脂（ｃ）とした。比較用吸水性樹脂（ｃ）の粒度分布の形状はシャープな山状でピークは一つであった。
［比較例４］
参考例１で得た吸水性樹脂（３Ｃ）を比較用吸水性樹脂（ｄ）とした。比較用吸水性樹脂（ｄ）の粒度分布の形状はシャープな山状でピークは一つであった。
［比較例５］
参考例１で得た吸水性樹脂（３Ｄ）を比較用吸水性樹脂（ｅ）とした。比較用吸水性樹脂（ｅ）の粒度分布の形状はシャープな山状でピークは一つであった。
【００５０】
上記で得られた吸水性樹脂（ａ）〜（ｈ）、比較用吸水性樹脂（ａ）〜（ｅ）について、正規標準偏差値、血液吸収量、血液ゲル吸収量を測定した。その結果を表１に示す。
【００５１】
【表１】
［実施例８］
ティッシュ（２２ｃｍ×６．８ｃｍ）の上に、実施例１で得られた吸水性樹脂（ａ）をできるだけ均一にまいた（坪量０．０５ｇ／ｃｍ２）。その上にさらにティッシュを置き、吸水性樹脂（ａ）をサンドした。この吸水性樹脂（ａ）をサンドしたティッシュを約１０分間、熱プレス（１００℃×３００ｋｇ／ｃｍ２）にかけ、ポリマーシートを作製した。このポリマーシートの表面に液透過性ポリプロピレン製シートを置き、吸収性物品（ａ）を組み立てた。
［実施例９〜１５、比較例６〜１０］
実施例８において、吸水性樹脂（ａ）に代えて吸水性樹脂（ｂ）〜（ｈ）または比較用吸水性樹脂（ａ）〜（ｅ）を用いた以外は実施例８と同様にして、本発明の吸収性物品（ｂ）〜（ｈ）および比較用吸収性物品（ａ）〜（ｅ）を組み立てた。
【００５３】
上記で得られた吸収性物品（ａ）〜（ｈ）および比較用吸収性物品（ａ）〜（ｅ）について、血液戻り量▲１▼、▲２▼を評価した。その結果を表２に示す。
【００５４】
【表２】
【発明の効果】
本発明によると、血液吸収性および血液ゲル吸収性に優れた吸水性樹脂を得ることができる。したがって、この吸水性樹脂またはこれを用いた吸収性物品が血液を二度以上に分けて少量ずつ吸収した場合にも、その合計で十分に多くの血液を吸収することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water absorbent resin, a method for producing the same, and an absorbent article. In particular, the present invention relates to a water-absorbent resin excellent in blood gel absorption, a production method thereof, and an absorbent article using the same.
[0002]
[Prior art]
In recent years, water absorbent resins have been widely used as one of constituent materials of sanitary materials such as disposable diapers and sanitary napkins for the purpose of absorbing body fluids.
Examples of the water-absorbing resin include a cross-linked polyacrylic acid partially neutralized product, a hydrolyzate of starch-acrylonitrile graft polymer, a neutralized product of starch-acrylic acid graft polymer, and a vinyl acetate-acrylic acid ester copolymer. Known are saponified polymers, hydrolysates of acrylonitrile copolymers or acrylamide copolymers, cross-linked products thereof, and cross-linked products of cationic monomers.
[0003]
When the liquid to be absorbed is blood or the like, there is a special situation such as a decrease in the suction amount of the water-absorbent resin because the blood component surrounds each water-absorbent resin particle during blood absorption and hinders absorption. Even a water-absorbing resin with a high suction amount for blood does not necessarily have a high suction amount for blood.
In view of such circumstances, various proposals have been made as attempts to improve the blood absorption characteristics of the water absorbent resin. For example, it has been proposed to add a compound such as sodium chloride or polyethylene glycol to the water-absorbent resin for the purpose of improving the absorbability of the water-absorbent resin to blood (Japanese Patent Laid-Open Nos. 58-501107 and 54). -70694). Also, attempts to improve the blood absorption rate of the nonwoven fabric for sanitary materials by making the highly water-absorbent fibers non-uniform (Japanese Patent Laid-Open No. 6-207358), and the upper layer and the lower layer are made of water-absorbing resins having different particle sizes. A structured laminate (Japanese Utility Model Laid-Open No. 6-58952) has been proposed. Certainly, the blood absorption characteristics are slightly improved by these configurations, but they are still insufficient for practical use.
[0004]
In order to solve this, International Publication No. 96-28515 introduces a new parameter called blood area ratio for ovine blood, and this blood-absorbing resin composition having a high blood area ratio exhibits excellent blood absorption characteristics. In addition, it is disclosed that a blood-absorbing resin composition having a high blood area ratio can be obtained by highly crosslinking the surface of the water-absorbing resin.
[0005]
[Problems to be solved by the invention]
According to the technique disclosed in International Publication No. 96-28515, the blood absorption characteristics are certainly improved, but if the water-absorbing resin absorbs blood in small portions by dividing it into two or more, the total It was found that there is a problem that the amount of blood that can be absorbed is smaller than when it is absorbed at once. In other words, once the water-absorbing resin absorbs blood to form a gel (blood gel), it cannot absorb the amount that should have been originally absorbable. For example, even if it is a water-absorbing resin that can absorb 10 g of blood if it absorbs blood at a stroke, after it absorbs 3 g of blood first and becomes a blood gel after a while, an additional 7 g It is impossible to absorb blood. Therefore, even if the water-absorbing resin has a large amount of blood absorption, if the blood gel absorbability is poor, the characteristic of having a large amount of blood absorption is not fully utilized, resulting in poor practicality.
[0006]
Therefore, the subject of this invention is providing the water absorbing resin excellent in blood gel absorbability, its manufacturing method, and an absorbent article using the same.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following configuration.
(1) A surface-crosslinked powdery water-absorbent resin, wherein the surface cross-link is based on 100 parts by weight of the water-absorbent resin. At least one selected from ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerol and diglycerol Polyhydric alcohol Is The surface cross-linking agent is used by 0.5 to 10 parts by weight, the average particle size is 100 to 800 μm, and the normal standard deviation of the particle size distribution is 130. μm A water-absorbent resin characterized by the above.
However, The water absorbent resin is obtained by polymerizing a water-soluble unsaturated monomer in which 30 to 90 mol% of acrylic acid is neutralized with a basic substance, The average particle size is determined by sieving the sample resin using a JIS standard sieve (aperture 850 μm, 710 μm, 600 μm, 500 μm, 425 μm, 355 μm, 300 μm, 250 μm, 180 μm, 150 μm, 100 μm, 75 μm, 45 μm), and then the residual percentage. Plot R on normal probability paper, R = 50 mass % (The same applies hereinafter).
The normal standard deviation is defined by the following formula (the same applies hereinafter).
[Expression 2]
[0009]
( 2 ) As described in (1) above, A method for producing a powdery water-absorbing resin having an average particle size of 100 to 800 μm, based on 100 parts by weight of the water-absorbing resin At least one selected from ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerol and diglycerol Polyhydric alcohol Is Including a step of mixing two or more types of surface-crosslinked powdery water-absorbing resins having different average particle diameters, which are surface-crosslinked by using 0.5 to 10 parts by weight of a surface-crosslinking agent. And a method for producing a water-absorbent resin.
[0011]
( Three ) (1 ) The water-absorbing resin according to the description has a basis weight of 20 to 10,000 g / m. 2 Used in , Absorbent article.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
When the liquid to be absorbed is artificial urine, there was almost no difference in the liquid absorption between the case where it was absorbed more than once and the case where it was absorbed at one time. It is thought that this is a peculiar problem. In consideration of the fact that blood is more likely to cause gel blocking than artificial urine, the biggest difference between artificial urine and blood is that blood is a solid component in addition to a liquid component, such as blood cells Therefore, it was speculated that blood cells and the like were the cause of inhibiting blood gel absorbability. Further investigation has been conducted, and since the inside of the blood cell is water, when the blood is absorbed by the water absorbent resin, the water in the blood cell is also absorbed by the water absorbent resin, and the surface film of the blood cell adheres to the surface of the water absorbent resin. It was thought that the water-absorbent resin gelled in this state, and the contact between the water-absorbent resin and a new liquid (blood) was hindered by the blood cell surface film.
[0013]
The particle size distribution of the water-absorbent resin obtained by the usual manufacturing method is an ordinary mountain shape, the largest is the particle size around the average particle size, and the proportion of the very small particle size or the very large particle size is small It has become. Many conventional techniques have a problem of sharpening the particle size distribution (JP-A-2-191604, JP-A-3-227301, JP-A-6-507564, etc.). This tendency is particularly remarkable. In general, it is known that a water-absorbing resin having the same composition correlates well with the blood absorption rate, and the smaller the particle size, the higher the blood absorption rate. Accordingly, when the water-absorbing resin comes into contact with blood, the water-absorbing resin having a smaller particle size absorbs a larger amount of liquid. Since ordinary water-absorbing resins have a small proportion of particles with a very small particle size, when they first come into contact with blood, the water-absorbing resin with these extremely small particle sizes alone is not sufficient in absolute liquid absorption, and particles near the average particle size. A water-absorbing resin of a diameter also absorbs a considerable amount of liquid. That is, since most of the water-absorbent resin absorbs a considerable amount of liquid when it comes into contact with blood for the first time, blood cells adhere to the surface of the majority of the water-absorbent resin. In other words, since the water-absorbing resin without adhesion of blood cells does not remain on the surface, the liquid cannot be sufficiently absorbed the next time it comes into contact with blood. In order to enhance the blood gel absorbability, the present inventors hardly absorb liquid when the water-absorbing resin comes into contact with blood for the first time, and then absorb water for the first time when it comes into contact with blood again. It is considered that it is effective to increase the ratio of the above, and the present invention has been achieved.
[0014]
That is, in the present invention, the distribution of the blood absorption rate of the water-absorbent resin is sufficiently widened so that the first time it contacts the blood, the water-absorbent resin absorbs only the water-absorbent resin having the higher blood absorption rate (small average particle size). A lot of water-absorbing resin, that is, the water-absorbing resin having a small blood absorption rate (large average particle size) is left on the surface without blood cell adhesion in preparation for the next contact with blood. It is to keep.
[0015]
That is, the present invention provides a method for mixing two or more water-absorbing resins having different blood absorption rates as a method for producing a water-absorbing resin. The blood absorption rate is defined in Examples described later, and quantifies the amount of water-absorbing resin that absorbs blood in a predetermined time (1 minute). There is at least one difference in the difference in blood absorption rate between the water-absorbing resins to be mixed (in the case of mixing three or more water-absorbing resins, it means the difference between the adjoining blood absorption rates). It is preferably 0.05 g / g / second or more, more preferably 0.10 g / g / second or more, and still more preferably 0.15 g / g / second or more. Among the water-absorbing resins to be mixed, the blood absorption rate of the largest blood absorption rate is preferably in the range of 0.10 to 0.33 g / g / second, preferably 0.15 to 0.25 g / g / second. It is more preferable that it is in the range. Further, although the blood absorption rate is the lowest, the blood absorption rate is preferably in the range of 0.01 to 0.10 g / g / sec, and preferably in the range of 0.03 to 0.07 g / g / sec. Is more preferable. The water-absorbing resin to be mixed may be of the same composition or different from each other, but in the case of the same composition, the correlation between the blood absorption rate and the particle size is good, so There is an advantage that the blood absorption rate can be controlled by controlling.
[0016]
Therefore, the present invention also provides a method for mixing two or more powdery water absorbent resins having different average particle diameters as a method for producing the water absorbent resin. There is at least one difference among the difference in average particle diameter between the water-absorbing resins to be mixed (in the case of mixing three or more kinds of water-absorbing resins, the difference between the adjacent particles arranged in order of the average particle diameter). The thickness is preferably 100 μm or more, more preferably 300 μm or more, and further preferably 500 μm. Among the water-absorbing resins to be mixed, the average particle diameter of the largest average particle diameter is preferably in the range of 300 to 1000 μm, and more preferably in the range of 400 to 800 μm. The average particle diameter of the smallest average particle diameter is preferably in the range of 1 to 300 μm, and more preferably in the range of 10 to 100 μm.
[0017]
In order to obtain two or more powdery water absorbent resins having different average particle diameters, it is convenient to classify the powder water absorbent resin into a plurality of particle size ranges. After classifying the water-absorbing resin, it is preferable to mix two or more types of water-absorbing resins having a particle size range that does not overlap each other obtained by classification, because the compositions of the water-absorbing resins to be mixed are the same. In particular, among the water-absorbing resins having a plurality of particle size ranges obtained by classification, one or more water-absorbing resins that are not adjacent to each other are mixed rather than mixing water-absorbing resins having a particle size range adjacent to each other. This is preferable because the particle diameter of the obtained water-absorbent resin is broadened. For example, when water-absorbing resins having three particle sizes ranging from 150 to 300 μm, 300 to 600 μm, and 600 to 850 μm are obtained by classification, the water-absorbing resin of 150 to 300 μm and the water-absorbing resin of 300 to 600 μm are: The particle size range is adjacent at “300 μm”, and the water absorbent resin of 300 to 600 μm and the water absorbent resin of 600 to 850 μm are adjacent to each other in the particle size range of “600 μm”, so the 300 to 600 μm water absorbent resin in the middle is used. First, it is preferable to mix 150-300 μm water-absorbing resin and 600-850 μm water-absorbing resin at both ends.
[0018]
In order to fully demonstrate the effects of the present invention, it is preferable to make the mixing ratio of two or more kinds of water-absorbing resins to be mixed as much as possible, specifically, the largest amount and the smallest amount. The weight ratio is preferably within 2 times, preferably within 1.5 times, and more preferably within 1.2 times.
By the above manufacturing method, the normal standard deviation of the particle size distribution of the present invention is 130. μm The above powdery water-absorbing resin can be obtained. The normal standard deviation of the particle size distribution of the water absorbent resin is 170. μm Or more, preferably 210 μm More preferably. In the water-absorbent resin obtained by the usual production method, the normal standard deviation is 115 at most. μm It is thought to be about. Normal standard deviation is 130 μm As a form of the particle size distribution as described above, (1) Having two or more peaks, (2) There is one peak, but examples are extremely broad or trapezoidal. In order to fully demonstrate the effects of the present invention, (2) Than (1) Is preferred, and (1) At least one of the distances between peaks (in the case of having three or more peaks, the distance between adjacent peaks) is preferably 100 μm or more, and more preferably 300 μm or more. If the distance between peaks is short, the effect of having two or more peaks is low, and almost all of the water-absorbing resin will absorb liquid when it comes into contact with blood for the first time. The proportion of water absorbent resin that can be performed is reduced. Of the peaks, the peak having the smallest particle size is preferably in the range of 1 to 300 μm, and more preferably in the range of 10 to 200 μm. Moreover, the peak on the side with the largest particle diameter is preferably in the range of 300 to 1000 μm, and more preferably in the range of 400 to 800 μm. (1) The particle size distribution in the form can be easily obtained by mixing, for example, water-absorbing resins having a particle size range not adjacent to each other. (2) The particle size distribution in the form of can be easily obtained by, for example, mixing water absorbent resins having particle size distributions adjacent to each other as much as possible.
[0019]
The average particle diameter of the water absorbent resin of the present invention is preferably in the range of 100 to 800 μm, and more preferably in the range of 300 to 600 μm.
The water-absorbing resin of the present invention is characterized by a high blood gel absorption, and can easily achieve 2 g / g or more. The blood gel absorption amount is defined in Examples described later, and quantifies the amount of blood absorption in a state where the water-absorbent resin absorbs blood to form a gel. The higher the amount of blood gel absorbed, the greater the amount of blood that can be absorbed in total even when the water-absorbent resin absorbs blood more than once. The blood gel absorption is preferably 2.5 g / g or more, more preferably 3 g / g or more.
[0020]
In the water-absorbent resin of the present invention, it is preferable that the blood suction amount is high in order to take full advantage of the high blood gel absorption amount. The blood aspiration amount is defined in Examples described later, and quantifies the force with which the water-absorbing resin draws blood. The blood suction amount is preferably 5 g / g or more, more preferably 10 g / g or more. In order to obtain a water-absorbing resin having a high blood suction amount, the blood suction amount of each water-absorbing resin to be mixed is preferably high, and is preferably 5 g / g or more, more preferably 10 g / g. That's it.
[0021]
The water absorption capacity of the water absorbent resin of the present invention is preferably about 20 to 60 g / g as measured by the tea bag method in physiological saline. The proportion of uncrosslinked components, so-called water-soluble components, is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably.
The water-absorbing resin used in the present invention is not particularly limited as long as it absorbs water and causes volume expansion, but it is generally obtained by polymerizing a water-soluble unsaturated monomer. Examples of these water-soluble unsaturated monomers include (meth) acrylic acid, (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) Anionic monomers and salts thereof such as acryloylpropane sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid; (meth) acrylamide, N-substituted (meth) acrylamide, Nonionic hydrophilic group-containing monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and polyethylene glycol (meth) acrylate, N, N-dimethylaminoethyl (Meth) acrylate, N, N-dimethylaminop Pill (meth) acrylate, N, may be mentioned N- dimethylaminopropyl (meth) amino group-containing unsaturated monomers and their quaternary compound such as acrylamide or the like in detail. In addition, the amount of the polymer obtained does not extremely hinder the hydrophilicity, for example, acrylic esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, vinyl acetate, propionic acid Hydrophobic monomers such as vinyl may be used. As the monomer component, one or more of these can be selected and used, but considering the water absorption characteristics of the finally obtained water absorbent article, (meth) acrylic acid (salt), 2- (meth) acryloylethanesulfonic acid (salt), 2- (meth) acrylamide-2-methylpropanesulfonic acid (salt), (meth) acrylamide, methoxypolyethylene glycol (meth) acrylate, N, N-dimethylaminoethyl One or more selected from the group consisting of (meth) acrylates or quaternized products thereof are preferred, and those containing (meth) acrylic acid (salt) as an essential component are more preferred. In this case, it is most preferable that 30 to 90 mol% of (meth) acrylic acid is neutralized with a basic substance.
[0022]
In addition, the water-absorbing resin may be a self-crosslinking type obtained without using a cross-linking agent. It may be obtained using a range that reaches a desired standard. In this case, examples of the internal crosslinking agent used for crosslinking inside the water-absorbent resin include, for example, N, N′-methylenebis (meth) acrylamide, (poly) ethylene glycol (meth) acrylate, glycerin tri (meth) acrylate, tri Methylolpropane tri (meth) acrylate, triallylamine, triallyl cyanurate, triallyl isocyanurate, glycidyl (meth) acrylate, (poly) ethylene glycol, diethylene glycol, (poly) glycerin, propylene glycol, diethanolamine, trimethylolpropane, penta Erythritol, (poly) ethylene glycol diglycidyl ether, (poly) glycerol (poly) glycidyl ether, epichlorohydrin, ethylenediamine, polyethyleneimine, (Ii) Specific examples include aluminum chloride, aluminum sulfate, calcium chloride, magnesium sulfate and the like. Among these, one or more kinds can be used in consideration of reactivity.
[0023]
By cross-linking the vicinity of the surface of the water-absorbent resin, the blood suction amount and blood absorption amount of the water-absorbent resin can be increased. As the surface cross-linking agent, those having two or more functional groups capable of reacting with the functional group on the surface of the water-absorbent resin, and those having high safety when used for absorbent articles such as sanitary napkins are preferable. Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, trimethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, pinacol, hydrobenzoin, benzpinacol, cyclopentane-1,2-diol, cyclohexane-1,4-diol, pentaerythritol, glycerin , Diglyceri , Polyglycerin, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block polymer, sorbit, sorbitan, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, trimethylolpropane, pentaerythritol, polyvinyl alcohol, glucose, Polyhydric alcohols such as mannitol, mannitan, sucrose, glucose; ethylene carbonate, propylene carbonate, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl-1,3-dioxolane-2 -One, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,3- Dioqui Alkylene carbonates such as n-2-one and 4,6-dimethyl-1,3-dioxan-2-one; polyvalent amines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and polyethyleneimine Polyvalent isocyanates such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; polyvalent oxazolines such as 1,2-ethylenebisoxazoline; 2,2-bishydroxymethylbutanol-tris [3- (1-aziridyl) propionate ], 1,6-hexamethylene diethylene urea, polyvalent aziridines such as diphenylmethane-bis-4,4′-N, N′-diethylene urea, and the like. As the surface cross-linking agent, one or more of these can be used. Among them, polyhydric alcohols and alkylene carbonates are preferable from the viewpoint of blood suction amount and blood absorption amount of the water-absorbing resin obtained, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, glycerin, diglycerin, polyglycerin, Ethylene carbonate and propylene carbonate are preferred, and glycerin is most preferred.
[0024]
Although the usage-amount of a surface crosslinking agent is not specifically limited, The range of 0.5-10 weight part is preferable with respect to 100 weight part of water absorbing resin, More preferably, it is the range of 2-5 weight part. When the amount used is less than 0.5 parts by weight, the blood suction amount and blood absorption amount of the water-absorbent resin obtained even if heated for a long time are difficult to increase. On the other hand, if the amount used exceeds 10 parts by weight, it is difficult to obtain an effect corresponding to the increase in the amount used, and unreacted substances remain, which not only causes various troubles but is also uneconomical. is there.
[0025]
In order to subject the water-absorbent resin to surface cross-linking treatment, the water-absorbent resin and the surface cross-linking agent are usually mixed and then granulated is heat-treated.
In order to uniformly mix the water absorbent resin and the surface crosslinking agent, 0 to 50 parts by weight of water and 0 to 60 parts by weight of the hydrophilic organic solvent may be used with respect to 100 parts by weight of the water absorbent resin.
Examples of hydrophilic organic solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, lower alcohols such as sec-butanol and t-butanol, ethers such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. , Ethers such as dioxane, tetrahydrofuran and diethyl ether, amides such as N, N-dimethylformamide and N, N-diethylformamide, and sulfoxides such as dimethyl sulfoxide.
[0026]
The mixing method is not particularly limited, and a normal mixer can be used.
When polyhydric alcohol or alkylene carbonate is used as the surface cross-linking agent, the heat treatment is preferably performed under the conditions indicated by the following formula (1), the temperature of the article to be heated and the heat treatment time.
log (t) ≧ 15.7 × 10 Three (1 / T) -24.4 (1)
(In the formula, t is the heat treatment time (second), and T is the absolute temperature (K) of the object to be heated.)
When heat treatment is performed under conditions that do not satisfy Expression (1), the blood suction amount and the blood absorption amount are inferior. Furthermore, it is preferable to carry out under the conditions shown by the following formula (2).
[0027]
15.7 × 10 Three (1 / T) -23 ≧
log (t) ≧ 15.7 × 10 Three (1 / T) -24.4 (2)
(In the formula, t is the heat treatment time (second), and T is the absolute temperature (K) of the object to be heated.)
If the heat treatment is performed under a condition that does not satisfy the expression (2), it is difficult and uneconomical to obtain an effect equivalent to a long time spent.
[0028]
When the surface cross-linking agent is a polyhydric alcohol or alkylene carbonate, the specific temperature and heat treatment time of the object to be heated are preferably 170 ° C. for 18 hours to 70 hours to 250 ° C. for 5 minutes to 18 minutes. More preferably, it is 8 hours to 30 hours at 180 ° C. to 1 hour to 3 hours at 210 ° C. If the temperature of the object to be heated is less than 170 ° C., it takes a very long time to obtain a high blood suction amount and a high blood absorption amount, which is not economical. On the other hand, if the temperature of the object to be heated exceeds 250 ° C., there is a risk of causing thermal degradation depending on the type of the water absorbent resin used.
[0029]
In the present invention, the heating method is not particularly limited, and is an ordinary dryer or heating furnace, for example, a grooved stirring dryer, a rotary dryer, a fluidized bed dryer, an air dryer, an infrared dryer, a dielectric heater, etc. Can be used. It is preferable that the shearing force and the crushing force during the heat treatment are as small as possible in order to obtain an excellent blood suction amount and blood absorption amount. Among them, a fluidized bed dryer and an air flow dryer are preferable.
[0030]
In the present invention, the water-absorbing resin subjected to surface cross-linking may be classified, or after classifying into a water-absorbing resin, each may be subjected to surface cross-linking.
The absorbent article of the present invention is configured by combining the water-absorbent resin of the present invention with necessary members such as hydrophilic fibers. Basis weight is 20-10000 g / m 2 Is generally in the range of 100 to 1000 g / m 2 Is preferable, 200 to 600 g / m 2 The range of is more preferable.
[0031]
As the hydrophilic fiber used in the absorbent article of the present invention, any known fiber can be used. For example, pulverized wood pulp, cotton linter, crosslinked cellulose fiber, rayon, cotton, wool, acetate, vinylon, etc. can be used.
Among them, a pulverized wood pulp airlaid pad is preferable.
The absorptive article of the present invention may have many publicly known members, such as a diffusion layer, a leg elastic member, a waist elastic member, and a tape.
[0032]
The absorbent article of the present invention exhibits excellent absorption characteristics for blood as described above, but in addition to water containing protein components like blood, for example, milk, breast milk, origami etc. Shows excellent absorption characteristics. In addition, it exhibits excellent absorption characteristics for urine, seawater, cement water, soil water, fertilizer-containing water, rainwater, drainage, and the like similar to conventional water absorbent resins. Specific applications include sanitary napkins, tampons, medical blood-absorbing articles, wound protection materials, wound healing materials, surgical waste fluid treatment agents, and other applications that require blood absorption characteristics, as well as disposable diapers and incontinence pads. It is also preferably used in various industrial fields such as sanitary materials such as civil engineering, agriculture and horticulture. Furthermore, it is obtained by interposing a deodorant, a fragrance, a drug, a plant growth aid, a bactericide, a foaming agent, a pigment, a dye, a hydrophilic short fiber, a fertilizer, etc. in the water absorbent resin or absorbent article of the present invention. A new function can be imparted to the water absorbent resin or absorbent article.
[0033]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these.
In the examples, “parts” represents “parts by weight” unless otherwise specified.
[0034]
Various performances of the water absorbent resin were measured by the following methods.
(A) Blood suction volume
Add about 1 g of sample resin to 16 layers of toilet paper (55 mm x 75 mm) soaked in 20 ml of sheep blood (sheep defibrinated blood; manufactured by Nippon Biotest Laboratories, the same below) in a petri dish with an inner diameter of 95 mm for 5 minutes. After absorbing the liquid, the swollen gel was collected and its weight was measured. The weight of the swollen gel after liquid absorption was divided by the weight of the original sample resin to calculate the blood suction amount (g / g) of the sample resin.
(B) Blood absorption
1 g of sample resin is spread as evenly as possible in a petri dish having an inner diameter of 60 mm, and 5 g of amniotic blood is dropped on the sample resin to obtain a gel that sucks blood. Most water-absorbing resins do not form a uniform gel in this state.
[0035]
Next, after leaving for 5 minutes, place a kitchen towel (10 sheets) on the gel and put weight on it (load 0.7psi = 49g / cm) 2 ) Was measured, and the weight of the kitchen towel after 1 minute was measured, and the value obtained by subtracting the weight change from the dropped ovine blood was taken as the blood absorption.
(C) Blood gel absorption
1 g of sample resin is spread as evenly as possible in a petri dish having an inner diameter of 60 mm, and 5 g of amniotic blood is dropped on the sample resin to obtain a gel that sucks blood.
[0036]
After standing for 60 minutes, 5 g of ovine blood was dropped on the gel that had sucked the blood, and after standing for 5 minutes, a kitchen towel (10 sheets) was placed on the gel and a weight (load 0.7 psi = 49 g / cm 2 ) Was measured, and the weight of the kitchen towel after 1 minute was measured, and the value obtained by subtracting the weight change from the dropped ovine blood was taken as the blood gel absorption.
(D) Blood return amount
About 15 g of amniotic blood was dropped with a syringe into the center of the absorbent article, and after about 5 minutes, the surface of the absorbent article was touched by hand to evaluate the return amount, which was defined as blood return amount (1). Further, after 1 hour, 15 g of amniotic blood was dropped with a syringe, and after about 5 minutes, the surface of the absorbent article was touched with the hand to evaluate the return amount, which was defined as blood return amount (2).
(E) Blood absorption rate
Add about 1 g of sample resin onto 16 sheets of toilet paper (55 mm x 75 mm) soaked in 20 ml of amniotic blood in a petri dish with an inner diameter of 95 mm, let it absorb for 1 minute, collect the swollen gel, and measure its weight did. The blood absorption rate was calculated according to the following formula.
[0037]
[Expression 1]
(F) Average particle size / particle size distribution
The average particle size is determined by sieving the sample resin using a JIS standard sieve (aperture 850 μm, 710 μm, 600 μm, 500 μm, 425 μm, 355 μm, 300 μm, 250 μm, 180 μm, 150 μm, 100 μm, 75 μm, 45 μm), and then the residual percentage. R was plotted on normal probability paper, and the particle size corresponding to R = 50% was taken as the average particle size.
[0039]
As the particle size distribution, a normal standard deviation value represented by the following formula was used as an index. Here, the larger the normal standard deviation value, the wider the particle size distribution.
[0040]
[Expression 2]
(X 0 Is R = 50%, X 1 R = 84.1%, X 2 Is the respective particle size when R = 15.9%)
[Example 1]
In the production of a water-absorbing resin having a carboxyl group, 2.400 parts of a 37% by weight aqueous solution of sodium acrylate (a neutralization rate of 75 mol%) as a monomer component was added to 2.72 of trimethylolpropane triacrylate as an internal crosslinking agent. Part was dissolved to prepare a reaction solution. Next, this reaction solution was degassed for 30 minutes in a nitrogen gas atmosphere.
[0042]
Next, the reaction solution was supplied to a reactor having a lid on a jacketed stainless steel double-arm kneader having two sigma blades, and the reactor was purged with nitrogen gas while maintaining the reaction solution at 30 ° C. Subsequently, while stirring the reaction solution, 1.1 parts of sodium persulfate as a polymerization initiator and 1.1 parts of sodium sulfite as a reducing agent for promoting the decomposition of the polymerization initiator were added. Polymerization started later. Then, polymerization was performed at 30 ° C. to 80 ° C., and the hydrogel polymer was taken out 40 minutes after the polymerization was started.
[0043]
The obtained hydrogel polymer was spread on a wire mesh and dried with hot air at 150 ° C. for 2 hours.
Next, the dried product was pulverized using a hammer mill, and further classified with a wire mesh having an opening of 850 μm to obtain a water absorbent resin (1) having an average particle diameter of 400 μm.
Next, an aqueous liquid containing 0.5 part of glycerin, 2 parts of water and 0.5 part of isopropyl alcohol was added to 100 parts of the obtained water absorbent resin (1) with a Redige mixer (M5R, manufactured by Redige Co., Ltd.). Mixing for 30 minutes, the resulting water-absorbent resin mixture (1) was placed in a drier and heat-treated at 220 ° C. for 2 hours to obtain a water-absorbent resin (2). The blood suction amount of the water absorbent resin (2) was 12.5 g / g.
[0044]
The water-absorbing resin (2) is classified with an opening of 850 μm, 600 μm, 300 μm, and 150 μm, the water-absorbing resin (2A) from 850 μm to 600 μm, the water-absorbing resin (2B) from 600 μm to 300 μm, and the water-absorbing resin from 300 μm to 150 μm ( 2C), 150 μm or less was designated as a water absorbent resin (2D). The blood absorption rates of the water absorbent resins (2A), (2B), (2C) and (2D) are 0.04 g / g / sec, 0.09 g / g / sec, 0.13 g / g / sec and 0, respectively. .18 g / g / sec. The blood suction amounts of the water absorbent resins (2A), (2B), (2C), and (2D) were 13.1 g / g, 12.8 g / g, 12.2 g / g, and 12.0 g / g, respectively. The average particle diameters were 710 μm, 420 μm, 240 μm, and 92 μm, respectively.
[0045]
50 parts of the water absorbent resin (2A) and 50 parts of the water absorbent resin (2D) were mixed to obtain the water absorbent resin (a) of the present invention. The blood suction amount of the water absorbent resin (a) was 12.6 g / g. The water absorbent resin (a) had an average particle diameter of 410 μm and had two peaks at 700 μm and 100 μm.
[Example 2]
50 parts of the water absorbent resin (2A) obtained in Example 1 and 50 parts of the water absorbent resin (2C) were mixed to obtain the water absorbent resin (b) of the present invention. The blood suction amount of the water absorbent resin (b) was 12.4 g / g. The water absorbent resin (b) had an average particle diameter of 480 μm and had two peaks at 700 μm and 250 μm.
[Example 3]
50 parts of the water absorbent resin (2B) obtained in Example 1 and 50 parts of the water absorbent resin (2D) were mixed to obtain the water absorbent resin (c) of the present invention. The blood suction amount of the water absorbent resin (c) was 12.3 g / g. The water absorbent resin (c) had an average particle diameter of 250 μm and had two peaks at 410 μm and 100 μm.
[Example 4]
25 parts of the water absorbent resin (2A) obtained in Example 1, 25 parts of the water absorbent resin (2B), 25 parts of the water absorbent resin (2C) and 25 parts of the water absorbent resin (2D) were mixed, and the water absorbent of the present invention. Resin (d) was obtained. The blood suction amount of the water absorbent resin (d) was 12.5 g / g. The water absorbent resin (d) had an average particle size of 390 μm and the shape of the particle size distribution was trapezoidal.
[ reference Example 1 ]
The water-absorbent resin (1) obtained in Example 1 was classified with an opening of 850 μm, 600 μm, 300 μm, and 150 μm, 850 μm to 600 μm were classified into the water absorbent resin (1A), 600 μm to 300 μm were classified into the water absorbent resin (1B), and 300 μm to 150 μm was the water absorbent resin (1C), and 150 μm or less was the water absorbent resin (1D).
[0046]
An aqueous liquid containing 0.2 part of glycerin, 1 part of water and 0.5 part of isopropyl alcohol is added to 100 parts of the obtained water absorbent resin (1A) with a Redige mixer (M5R, manufactured by Redige) for about 30 minutes. The obtained water absorbent resin mixture (1A) was put in a drier and heat-treated at 220 ° C. for 2 hours to obtain a water absorbent resin (3A). The water absorbing resin (3A) had a blood suction amount of 12.8 g / g, a blood absorption rate of 0.05 g / g / sec, and an average particle size of 730 μm.
[0047]
An aqueous liquid containing 0.4 part of glycerin, 2 parts of water and 0.5 part of isopropyl alcohol was added to 100 parts of the obtained water-absorbing resin (1B) with a Redige mixer (M5R, manufactured by Redige) for about 30 minutes. The obtained water-absorbent resin mixture (1B) was placed in a dryer and heat-treated at 220 ° C. for 2 hours to obtain a water-absorbent resin (3B). The water absorbing resin (3B) had a blood suction amount of 12.5 g / g, a blood absorption rate of 0.11 g / g / sec, and an average particle size of 440 μm.
[0048]
An aqueous liquid containing 0.6 part of glycerin, 2 parts of water and 0.5 part of isopropyl alcohol is added to a 100 parts of the water-absorbing resin (1C) with a Redige mixer (M5R, manufactured by Redige) for about 30 minutes. The obtained water-absorbent resin mixture (1C) was placed in a drier and heat-treated at 220 ° C. for 2 hours to obtain a water-absorbent resin (3C). The blood-absorbing resin (3C) had a blood suction amount of 11.9 g / g, a blood absorption rate of 0.15 g / g / sec, and an average particle size of 280 μm.
An aqueous liquid containing 1 part of glycerin, 4 parts of water and 1 part of isopropyl alcohol was mixed with 100 parts of the obtained water-absorbent resin (1D) with a Redige mixer (M5R, manufactured by Redige) for about 30 minutes. The obtained water-absorbing resin mixture (1D) was placed in a dryer and heat-treated at 220 ° C. for 2 hours to obtain a water-absorbing resin (3D). The blood absorption amount of the water absorbent resin (3D) was 12.7 g / g, the blood absorption rate was 0.20 g / g / sec, and the average particle size was 140 μm.
[0049]
50 parts of the water absorbent resin (3A) and 50 parts of the water absorbent resin (3D) were mixed to obtain the water absorbent resin (e) of the present invention. The blood suction amount of the water absorbent resin (e) was 12.7 g / g. The water absorbent resin (e) had an average particle diameter of 430 μm and had two peaks at 720 μm and 150 μm.
[Example 5 ]
50 parts of the water absorbent resin (3A) obtained in Example 1 and 50 parts of the water absorbent resin (3C) were mixed to obtain the water absorbent resin (f) of the present invention. The blood suction amount of the water absorbent resin (f) was 12.4 g / g. The water absorbent resin (f) had an average particle size of 500 μm and had two peaks at 720 μm and 290 μm.
[Example 6 ]
50 parts of the water absorbent resin (3B) obtained in Example 1 and 50 parts of the water absorbent resin (3D) were mixed to obtain the water absorbent resin (g) of the present invention. The blood suction amount of the water absorbent resin (g) was 12.6 g / g. The water absorbent resin (g) had an average particle size of 300 μm and had two peaks at 430 μm and 150 μm.
[Example 7 ]
25 parts of the water absorbent resin (3A) obtained in Example 1, 25 parts of the water absorbent resin (3B), 25 parts of the water absorbent resin (3C), and 25 parts of the water absorbent resin (3D) were mixed to obtain the water absorbent of the present invention. Resin (h) was obtained. The blood suction amount of the water absorbent resin (h) was 12.5 g / g. The water absorbent resin (h) had an average particle size of 420 μm and a particle size distribution with a trapezoidal shape.
[Comparative Example 1]
The water absorbent resin (2) obtained in Example 1 was used as a comparative water absorbent resin (a). The shape of the particle size distribution of the comparative water absorbent resin (a) was mountain-shaped and had one peak.
[Comparative Example 2]
reference Example 1 The water-absorbent resin (3A) obtained in the above was used as a comparative water-absorbent resin (b). The shape of the particle size distribution of the comparative water absorbent resin (b) was a sharp mountain shape with one peak.
[Comparative Example 3]
reference Example 1 The water absorbent resin (3B) obtained in (1) was used as a comparative water absorbent resin (c). The shape of the particle size distribution of the comparative water absorbent resin (c) was a sharp mountain shape and had one peak.
[Comparative Example 4]
reference Example 1 The water-absorbent resin (3C) obtained in the above was used as a comparative water-absorbent resin (d). The shape of the particle size distribution of the comparative water absorbent resin (d) was a sharp mountain shape with one peak.
[Comparative Example 5]
reference Example 1 The water-absorbent resin (3D) obtained in the above was used as a comparative water-absorbent resin (e). The shape of the particle size distribution of the comparative water absorbent resin (e) was a sharp mountain shape with one peak.
[0050]
For the water-absorbing resins (a) to (h) and the comparative water-absorbing resins (a) to (e) obtained above, the normal standard deviation value, the blood absorption amount, and the blood gel absorption amount were measured. The results are shown in Table 1.
[0051]
[Table 1]
[Example 8 ]
On the tissue (22 cm × 6.8 cm), the water-absorbent resin (a) obtained in Example 1 was dispersed as uniformly as possible (basis weight 0.05 g / cm). 2 ). A tissue was further placed thereon to sand the water absorbent resin (a). The tissue sanded with the water-absorbent resin (a) was heated for about 10 minutes (100 ° C. × 300 kg / cm 2 ) To prepare a polymer sheet. An absorbent article (a) was assembled by placing a liquid-permeable polypropylene sheet on the surface of the polymer sheet.
[Example 9 ~ 15 Comparative Examples 6 to 10]
Example 8 In Example, except that water-absorbing resins (b) to (h) or comparative water-absorbing resins (a) to (e) were used instead of the water-absorbing resin (a) 8 In the same manner as described above, the absorbent articles (b) to (h) of the present invention and the comparative absorbent articles (a) to (e) were assembled.
[0053]
With respect to the absorbent articles (a) to (h) and the comparative absorbent articles (a) to (e) obtained above, the blood return amounts (1) and (2) were evaluated. The results are shown in Table 2.
[0054]
[Table 2]
【The invention's effect】
According to the present invention, a water absorbent resin excellent in blood absorbability and blood gel absorbability can be obtained. Therefore, even when this water-absorbing resin or an absorbent article using the same absorbs blood in two or more portions, a sufficient amount of blood can be absorbed in total.
Claims (5)
ただし、吸水性樹脂は、アクリル酸の３０〜９０モル％が塩基性物質で中和されている水溶性不飽和単量体を重合させることにより得られるものであり、平均粒径は、ＪＩＳ標準ふるい（目開き８５０μｍ、７１０μｍ、６００μｍ、５００μｍ、４２５μｍ、３５５μｍ、３００μｍ、２５０μｍ、１８０μｍ、１５０μｍ、１００μｍ、７５μｍ、４５μｍ）を用いて試料樹脂をふるい分級した後、残留百分率Ｒを正規確率紙にプロットし、Ｒ＝５０質量％に相当する粒径とする。
正規標準偏差は下記式で規定するものである。
However, the water-absorbing resin is obtained by polymerizing a water-soluble unsaturated monomer in which 30 to 90 mol% of acrylic acid is neutralized with a basic substance, and the average particle size is JIS standard. After classifying the sample resin using a sieve (mesh size 850 μm, 710 μm, 600 μm, 500 μm, 425 μm, 355 μm, 300 μm, 250 μm, 180 μm, 150 μm, 100 μm, 75 μm, 45 μm), the residual percentage R is plotted on the normal probability paper And a particle size corresponding to R = 50 mass %.
The normal standard deviation is defined by the following formula.
ただし、吸水性樹脂は、アクリル酸の３０〜９０モル％が塩基性物質で中和されている水溶性不飽和単量体を重合させることにより得られるものであり、平均粒径は、ＪＩＳ標準ふるい（目開き８５０μｍ、７１０μｍ、６００μｍ、５００μｍ、４２５μｍ、３５５μｍ、３００μｍ、２５０μｍ、１８０μｍ、１５０μｍ、１００μｍ、７５μｍ、４５μｍ）を用いて試料樹脂をふるい分級した後、残留百分率Ｒを正規確率紙にプロットし、Ｒ＝５０質量％に相当する粒径とする。 It is a manufacturing method of the powdery water absorbing resin of 100-800 micrometers of average particle diameters of Claim 1, Comprising: Ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerol with respect to 100 weight part of water absorbing resin And two or more kinds of surface-crosslinked powders having different average particle diameters, which are surface-crosslinked by using 0.5 to 10 parts by weight of a surface-crosslinking agent which is at least one polyhydric alcohol selected from diglycerin A method for producing a water-absorbent resin, comprising a step of mixing a water-absorbent resin in a shape.
However, the water-absorbing resin is obtained by polymerizing a water-soluble unsaturated monomer in which 30 to 90 mol% of acrylic acid is neutralized with a basic substance, and the average particle size is JIS standard. After classifying the sample resin using a sieve (mesh size 850 μm, 710 μm, 600 μm, 500 μm, 425 μm, 355 μm, 300 μm, 250 μm, 180 μm, 150 μm, 100 μm, 75 μm, 45 μm), the residual percentage R is plotted on the normal probability paper And a particle size corresponding to R = 50 mass %.
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| Application Number | Priority Date | Filing Date | Title |
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| JP05240298A JP4583516B2 (en) | 1998-03-04 | 1998-03-04 | Water absorbent resin, method for producing the same, and absorbent article |
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| JP05240298A JP4583516B2 (en) | 1998-03-04 | 1998-03-04 | Water absorbent resin, method for producing the same, and absorbent article |
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| JPH11246625A JPH11246625A (en) | 1999-09-14 |
| JPH11246625A5 JPH11246625A5 (en) | 2005-08-04 |
| JP4583516B2 true JP4583516B2 (en) | 2010-11-17 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8697812B2 (en) | 2010-11-22 | 2014-04-15 | Lg Chem, Ltd. | Preparation method of superabsorbent polymer |
| US9029480B2 (en) | 2010-11-30 | 2015-05-12 | Lg Chem, Ltd. | Preparation method of superabsorbent polymer |
| US9109097B2 (en) | 2013-01-15 | 2015-08-18 | Lg Chem, Ltd. | Method of preparing super absorbent polymer |
| US10858486B2 (en) | 2016-03-11 | 2020-12-08 | Lg Chem, Ltd. | Super absorbent polymer and method for producing same |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1433526A3 (en) | 2002-12-26 | 2007-03-14 | Nippon Shokubai Co., Ltd. | Water-absorbent resin composition |
| JP4615853B2 (en) * | 2002-12-26 | 2011-01-19 | 株式会社日本触媒 | Water absorbent resin composition |
| EP2076338B2 (en) † | 2006-09-25 | 2022-01-26 | Basf Se | Method for grading water-absorbent polymer particles |
| US8148485B2 (en) * | 2008-03-13 | 2012-04-03 | Nippon Shokubai Co., Ltd. | Production method for water-absorbing resin |
| CN102292396B (en) * | 2008-11-21 | 2014-09-10 | 巴斯夫欧洲公司 | Mixture of surface postcrosslinked superabsorbers with different surface postcrosslinking |
| EP2415439B1 (en) * | 2009-03-31 | 2014-11-19 | Sumitomo Seika Chemicals CO. LTD. | Water-absorbent sheet |
| KR20150024767A (en) | 2013-08-27 | 2015-03-09 | 주식회사 엘지화학 | Preparation method for super absorbent polymer |
| MY200103A (en) | 2017-03-23 | 2023-12-07 | Sumitomo Seika Chemicals | Method for producing particle mixture |
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1998
- 1998-03-04 JP JP05240298A patent/JP4583516B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8697812B2 (en) | 2010-11-22 | 2014-04-15 | Lg Chem, Ltd. | Preparation method of superabsorbent polymer |
| US9029480B2 (en) | 2010-11-30 | 2015-05-12 | Lg Chem, Ltd. | Preparation method of superabsorbent polymer |
| US9109097B2 (en) | 2013-01-15 | 2015-08-18 | Lg Chem, Ltd. | Method of preparing super absorbent polymer |
| US10858486B2 (en) | 2016-03-11 | 2020-12-08 | Lg Chem, Ltd. | Super absorbent polymer and method for producing same |
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| Publication number | Publication date |
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| JPH11246625A (en) | 1999-09-14 |
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