JP6808391B2 - Water-absorbent resin particles and their manufacturing method - Google Patents
Water-absorbent resin particles and their manufacturing method Download PDFInfo
- Publication number
- JP6808391B2 JP6808391B2 JP2016149743A JP2016149743A JP6808391B2 JP 6808391 B2 JP6808391 B2 JP 6808391B2 JP 2016149743 A JP2016149743 A JP 2016149743A JP 2016149743 A JP2016149743 A JP 2016149743A JP 6808391 B2 JP6808391 B2 JP 6808391B2
- Authority
- JP
- Japan
- Prior art keywords
- water
- resin particles
- absorbent resin
- weight
- vinyl monomer
- 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.)
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- 239000002245 particle Substances 0.000 title claims description 130
- 229920005989 resin Polymers 0.000 title claims description 115
- 239000011347 resin Substances 0.000 title claims description 115
- 239000002250 absorbent Substances 0.000 title claims description 101
- 238000004519 manufacturing process Methods 0.000 title description 19
- 239000000178 monomer Substances 0.000 claims description 70
- 150000003839 salts Chemical class 0.000 claims description 63
- 229920002554 vinyl polymer Polymers 0.000 claims description 63
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 claims description 58
- 229910052751 metal Inorganic materials 0.000 claims description 57
- 239000002184 metal Substances 0.000 claims description 57
- 229920000642 polymer Polymers 0.000 claims description 45
- 239000006096 absorbing agent Substances 0.000 claims description 35
- 230000002745 absorbent Effects 0.000 claims description 20
- 239000007788 liquid Substances 0.000 claims description 14
- 239000000470 constituent Substances 0.000 claims description 11
- 239000010954 inorganic particle Substances 0.000 claims description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 7
- 230000007062 hydrolysis Effects 0.000 claims description 5
- 238000006460 hydrolysis reaction Methods 0.000 claims description 5
- ZEMWIYASLJTEHQ-UHFFFAOYSA-J aluminum;sodium;disulfate;dodecahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.O.O.[Na+].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZEMWIYASLJTEHQ-UHFFFAOYSA-J 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 3
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims description 3
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 3
- 230000035699 permeability Effects 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 38
- 238000010521 absorption reaction Methods 0.000 description 35
- 239000003431 cross linking reagent Substances 0.000 description 33
- 238000000034 method Methods 0.000 description 28
- 238000002156 mixing Methods 0.000 description 24
- 238000006116 polymerization reaction Methods 0.000 description 23
- -1 alkali metal salt Chemical class 0.000 description 20
- 239000000499 gel Substances 0.000 description 18
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 15
- 239000007864 aqueous solution Substances 0.000 description 15
- 230000014759 maintenance of location Effects 0.000 description 15
- 239000000835 fiber Substances 0.000 description 14
- 238000005259 measurement Methods 0.000 description 14
- 239000000203 mixture Substances 0.000 description 14
- 239000002904 solvent Substances 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 12
- 125000004429 atom Chemical group 0.000 description 10
- 239000000017 hydrogel Substances 0.000 description 10
- 239000000243 solution Substances 0.000 description 10
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 239000003960 organic solvent Substances 0.000 description 8
- 238000003756 stirring Methods 0.000 description 8
- 230000008961 swelling Effects 0.000 description 8
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 7
- 239000004698 Polyethylene Substances 0.000 description 7
- 238000005336 cracking Methods 0.000 description 7
- 238000004132 cross linking Methods 0.000 description 7
- 238000001035 drying Methods 0.000 description 7
- 239000002504 physiological saline solution Substances 0.000 description 7
- 229920000573 polyethylene Polymers 0.000 description 7
- 125000001424 substituent group Chemical group 0.000 description 7
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 6
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 229920003023 plastic Polymers 0.000 description 6
- 239000004033 plastic Substances 0.000 description 6
- 239000004677 Nylon Substances 0.000 description 5
- 229920001131 Pulp (paper) Polymers 0.000 description 5
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 5
- 229910052783 alkali metal Inorganic materials 0.000 description 5
- 239000012298 atmosphere Substances 0.000 description 5
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 5
- 239000010419 fine particle Substances 0.000 description 5
- 238000009775 high-speed stirring Methods 0.000 description 5
- 229920001778 nylon Polymers 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 150000005846 sugar alcohols Polymers 0.000 description 5
- 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 4
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 244000269722 Thea sinensis Species 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- 239000008119 colloidal silica Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 230000002209 hydrophobic effect Effects 0.000 description 4
- 238000000691 measurement method Methods 0.000 description 4
- 230000027939 micturition Effects 0.000 description 4
- 238000006386 neutralization reaction Methods 0.000 description 4
- 125000000020 sulfo group Chemical group O=S(=O)([*])O[H] 0.000 description 4
- 238000010558 suspension polymerization method Methods 0.000 description 4
- 238000012360 testing method Methods 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
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-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
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- 125000003917 carbamoyl group Chemical group [H]N([H])C(*)=O 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 229920006037 cross link polymer Polymers 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 239000010408 film Substances 0.000 description 3
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 3
- 125000000524 functional group Chemical group 0.000 description 3
- 125000003055 glycidyl group Chemical group C(C1CO1)* 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000004745 nonwoven fabric Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 230000002441 reversible effect Effects 0.000 description 3
- 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 2
- BJELTSYBAHKXRW-UHFFFAOYSA-N 2,4,6-triallyloxy-1,3,5-triazine Chemical compound C=CCOC1=NC(OCC=C)=NC(OCC=C)=N1 BJELTSYBAHKXRW-UHFFFAOYSA-N 0.000 description 2
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 2
- FYRWKWGEFZTOQI-UHFFFAOYSA-N 3-prop-2-enoxy-2,2-bis(prop-2-enoxymethyl)propan-1-ol Chemical compound C=CCOCC(CO)(COCC=C)COCC=C FYRWKWGEFZTOQI-UHFFFAOYSA-N 0.000 description 2
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 2
- 206010021639 Incontinence Diseases 0.000 description 2
- RRHGJUQNOFWUDK-UHFFFAOYSA-N Isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-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
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 150000001412 amines Chemical class 0.000 description 2
- 125000003277 amino group Chemical group 0.000 description 2
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 description 2
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 2
- 239000011668 ascorbic acid Substances 0.000 description 2
- 229960005070 ascorbic acid Drugs 0.000 description 2
- 235000010323 ascorbic acid Nutrition 0.000 description 2
- 125000000656 azaniumyl group Chemical group [H][N+]([H])([H])[*] 0.000 description 2
- WERYXYBDKMZEQL-UHFFFAOYSA-N butane-1,4-diol Chemical compound OCCCCO WERYXYBDKMZEQL-UHFFFAOYSA-N 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 235000013339 cereals Nutrition 0.000 description 2
- ZSWFCLXCOIISFI-UHFFFAOYSA-N cyclopentadiene Chemical compound C1C=CC=C1 ZSWFCLXCOIISFI-UHFFFAOYSA-N 0.000 description 2
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- PHTQWCKDNZKARW-UHFFFAOYSA-N isoamylol Chemical compound CC(C)CCO PHTQWCKDNZKARW-UHFFFAOYSA-N 0.000 description 2
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- 239000011777 magnesium Substances 0.000 description 2
- ZGEGCLOFRBLKSE-UHFFFAOYSA-N methylene hexane Natural products CCCCCC=C ZGEGCLOFRBLKSE-UHFFFAOYSA-N 0.000 description 2
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- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 239000003242 anti bacterial agent Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
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- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
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- IQIXQINTSRHNDE-UHFFFAOYSA-N butanimidamide;dihydrochloride Chemical compound Cl.Cl.CCCC(N)=N IQIXQINTSRHNDE-UHFFFAOYSA-N 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
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- 239000003638 chemical reducing agent Substances 0.000 description 1
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- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 125000004093 cyano group Chemical group *C#N 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- 239000002781 deodorant agent Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- LSXWFXONGKSEMY-UHFFFAOYSA-N di-tert-butyl peroxide Chemical compound CC(C)(C)OOC(C)(C)C LSXWFXONGKSEMY-UHFFFAOYSA-N 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
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- 230000000855 fungicidal effect Effects 0.000 description 1
- 239000000417 fungicide Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000003100 immobilizing effect Effects 0.000 description 1
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- 239000003112 inhibitor Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229940035429 isobutyl alcohol Drugs 0.000 description 1
- 239000012948 isocyanate Substances 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 229940087305 limonene Drugs 0.000 description 1
- 235000001510 limonene Nutrition 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- FQPSGWSUVKBHSU-UHFFFAOYSA-N methacrylamide Chemical compound CC(=C)C(N)=O FQPSGWSUVKBHSU-UHFFFAOYSA-N 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- JESXATFQYMPTNL-UHFFFAOYSA-N mono-hydroxyphenyl-ethylene Natural products OC1=CC=CC=C1C=C JESXATFQYMPTNL-UHFFFAOYSA-N 0.000 description 1
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 1
- QYZFTMMPKCOTAN-UHFFFAOYSA-N n-[2-(2-hydroxyethylamino)ethyl]-2-[[1-[2-(2-hydroxyethylamino)ethylamino]-2-methyl-1-oxopropan-2-yl]diazenyl]-2-methylpropanamide Chemical compound OCCNCCNC(=O)C(C)(C)N=NC(C)(C)C(=O)NCCNCCO QYZFTMMPKCOTAN-UHFFFAOYSA-N 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- CCCMONHAUSKTEQ-UHFFFAOYSA-N octadecene Natural products CCCCCCCCCCCCCCCCC=C CCCMONHAUSKTEQ-UHFFFAOYSA-N 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- WXZMFSXDPGVJKK-UHFFFAOYSA-N pentaerythritol Chemical compound OCC(CO)(CO)CO WXZMFSXDPGVJKK-UHFFFAOYSA-N 0.000 description 1
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 235000020030 perry Nutrition 0.000 description 1
- 125000001476 phosphono group Chemical group [H]OP(*)(=O)O[H] 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920005862 polyol Polymers 0.000 description 1
- 150000003077 polyols Chemical class 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 1
- 239000003755 preservative agent Substances 0.000 description 1
- 230000002335 preservative effect Effects 0.000 description 1
- HJWLCRVIBGQPNF-UHFFFAOYSA-N prop-2-enylbenzene Chemical compound C=CCC1=CC=CC=C1 HJWLCRVIBGQPNF-UHFFFAOYSA-N 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000007870 radical polymerization initiator Substances 0.000 description 1
- 238000010526 radical polymerization reaction Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000002964 rayon Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 239000013557 residual solvent Substances 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 229910001379 sodium hypophosphite Inorganic materials 0.000 description 1
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 150000003440 styrenes Chemical class 0.000 description 1
- 125000001273 sulfonato group Chemical group [O-]S(*)(=O)=O 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000010557 suspension polymerization reaction Methods 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 150000003564 thiocarbonyl compounds Chemical class 0.000 description 1
- NCPXQVVMIXIKTN-UHFFFAOYSA-N trisodium;phosphite Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])[O-] NCPXQVVMIXIKTN-UHFFFAOYSA-N 0.000 description 1
- 239000006097 ultraviolet radiation absorber Substances 0.000 description 1
- 210000002700 urine Anatomy 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Landscapes
- Absorbent Articles And Supports Therefor (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Description
本発明は吸水性樹脂粒子及びその製造方法に関する。 The present invention relates to water-absorbent resin particles and a method for producing the same.
現在、紙おむつ、生理用ナプキン、失禁パット等の衛生材料には、パルプ等の親水性繊維とアクリル酸（塩）等とを主原料とする吸水性樹脂が吸収体として幅広く利用されている。近年のＱＯＬ（ｑｕａｌｉｔｙ ｏｆ ｌｉｆｅ）向上の観点からこれら衛生材料はより軽量かつ薄型のものへと需要が遷移しており、これに伴って親水性繊維の使用量低減が望まれるようになってきた。親水性繊維の使用量低減に従い、排尿等により膨潤した吸水性樹脂（ゲル）を固定する機能が低下し、吸収体のひび割れや変形が起こる課題があった。 Currently, for sanitary materials such as disposable diapers, sanitary napkins, and incontinence pads, a water-absorbent resin containing hydrophilic fibers such as pulp and acrylic acid (salt) as main raw materials is widely used as an absorber. From the viewpoint of improving QOL (Quality of Life) in recent years, the demand for these sanitary materials has shifted to lighter and thinner ones, and along with this, it has become desired to reduce the amount of hydrophilic fibers used. .. As the amount of hydrophilic fibers used decreased, the function of fixing the water-absorbent resin (gel) swollen due to urination or the like decreased, and there was a problem that the absorber cracked or deformed.
吸収体のひび割れや変形を抑止する手法として、嵩密度を規定し、吸水性樹脂粒子同士の衝突を抑制し、吸水性樹脂の壊れ性を低下する方法が既に知られている（例えば、特許文献１参照）。
しかしながら、この方法では膨潤前の吸水性樹脂粒子の壊れ性を低下することができるものの、膨潤後の吸収体の形状保持性を満足できるものではなかった。
また、吸収体のひび割れや変形を抑止する手法として、吸収体内部にゲル支持層を導入する方法が既に知られている（例えば、特許文献２参照）。しかしながら、吸収体内部の液の拡散性が変化し、ゲル本来の吸収性が発揮されない問題があった。
As a method of suppressing cracking and deformation of the absorber, a method of defining bulk density, suppressing collision between water-absorbent resin particles, and reducing the fragility of the water-absorbent resin is already known (for example, Patent Documents). 1).
However, although this method can reduce the breakability of the water-absorbent resin particles before swelling, it cannot satisfy the shape retention of the absorber after swelling.
Further, as a method of suppressing cracking or deformation of the absorber, a method of introducing a gel support layer inside the absorber is already known (see, for example, Patent Document 2). However, there is a problem that the diffusibility of the liquid inside the absorber changes and the original absorbability of the gel is not exhibited.
本発明の目的は、排尿後の吸収体のひび割れや変形を抑止する形状保持性に優れた吸水性樹脂粒子を提供することである。 An object of the present invention is to provide water-absorbent resin particles having excellent shape-retaining property, which suppresses cracking and deformation of the absorber after urination.
本発明者は、上記目的を達成すべく鋭意検討した結果、本発明に到達した。
すなわち、本発明は、水溶性ビニルモノマー（ａ１）及び／又は加水分解により水溶性ビニルモノマー（ａ１）となるビニルモノマー（ａ２）を必須構成単位とする重合体（Ａ）と、多価金属原子を３個以上含む多価金属塩（Ｂ）とを含む吸水性樹脂粒子であり、多価金属塩（Ｂ）が吸水性樹脂粒子の重量に基づいて０．５〜２０重量％含む吸水性樹脂粒子、及び前記重合体（Ａ）と多価金属原子を３個以上含む多価金属塩（Ｂ）の溶液とを混合する工程を有することを特徴とする吸水性樹脂粒子の製造方法である。
The present inventor has arrived at the present invention as a result of diligent studies to achieve the above object.
That is, the present invention comprises a polymer (A) containing a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis as an essential constituent unit, and a polyvalent metal atom. It is a water-absorbent resin particle containing a polyvalent metal salt (B) containing 3 or more of the above, and the water-absorbent resin containing 0.5 to 20% by weight of the polyvalent metal salt (B) based on the weight of the water-absorbent resin particles. A method for producing water-absorbent resin particles, which comprises a step of mixing the particles and a solution of the polymer (A) and a polyvalent metal salt (B) containing three or more polyvalent metal atoms.
本発明の吸水性樹脂粒子及び本発明の製造方法により得られる吸水性樹脂粒子は、排尿後の吸収体のひび割れや変形を抑止する形状保持性に優れる。そのため、様々の使用状況においても安定して優れた吸収性能を発揮する。 The water-absorbent resin particles of the present invention and the water-absorbent resin particles obtained by the production method of the present invention are excellent in shape retention that suppresses cracking and deformation of the absorber after urination. Therefore, it exhibits stable and excellent absorption performance even in various usage conditions.
本発明の吸水性樹脂粒子は、水溶性ビニルモノマー（ａ１）及び／又は加水分解により水溶性ビニルモノマー（ａ１）となるビニルモノマー（ａ２）を必須構成単位とする重合体（Ａ）と、多価金属原子を３個以上含む多価金属塩（Ｂ）とを含む吸水性樹脂粒子である。 The water-absorbent resin particles of the present invention include a polymer (A) containing a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis as an essential constituent unit. It is a water-absorbent resin particle containing a polyvalent metal salt (B) containing three or more valent metal atoms.
本発明における水溶性ビニルモノマー（ａ１）としては特に限定はなく、公知のモノマー、例えば、特許第３６４８５５３号公報の０００７〜００２３段落に開示されている少なくとも１個の水溶性置換基とエチレン性不飽和基とを有するビニルモノマー（例えばアニオン性ビニルモノマー、非イオン性ビニルモノマー及びカチオン性ビニルモノマー）、特開２００３−１６５８８３号公報の０００９〜００２４段落に開示されているアニオン性ビニルモノマー、非イオン性ビニルモノマー及びカチオン性ビニルモノマー並びに特開２００５−７５９８２号公報の００４１〜００５１段落に開示されているカルボキシ基、スルホ基、ホスホノ基、水酸基、カルバモイル基、アミノ基及びアンモニオ基からなる群から選ばれる少なくとも１種を有するビニルモノマーが使用できる。 The water-soluble vinyl monomer (a1) in the present invention is not particularly limited, and is a known monomer, for example, at least one water-soluble substituent disclosed in paragraphs 0007 to 0023 of Japanese Patent No. 36485553 and ethylenia-free. Vinyl monomers having a saturated group (for example, anionic vinyl monomers, nonionic vinyl monomers and cationic vinyl monomers), anionic vinyl monomers and nonionic vinyl monomers disclosed in paragraphs 0009 to 0024 of JP-A-2003-165883. Selected from the group consisting of a sex vinyl monomer, a cationic vinyl monomer, and a carboxy group, a sulfo group, a phosphono group, a hydroxyl group, a carbamoyl group, an amino group, and an ammonio group disclosed in paragraphs 0041 to 0051 of JP-A-2005-75982. Vinyl monomers having at least one of these can be used.
加水分解により水溶性ビニルモノマー（ａ１）となるビニルモノマー（ａ２）［以下、加水分解性ビニルモノマー（ａ２）ともいう。］は特に限定はなく、公知｛例えば、特許第３６４８５５３号公報の００２４〜００２５段落に開示されている加水分解により水溶性置換基となる加水分解性置換基を少なくとも１個有するビニルモノマー、特開２００５−７５９８２号公報の００５２〜００５５段落に開示されている少なくとも１個の加水分解性置換基［１，３−オキソ−２−オキサプロピレン（−ＣＯ−Ｏ−ＣＯ−）基、アシル基及びシアノ基等］を有するビニルモノマー｝のビニルモノマー等が使用できる。なお、水溶性ビニルモノマーとは、当業者に周知の概念であるが、数量を用いて表すなら、例えば、２５℃の水１００ｇに少なくとも１００ｇ溶解するビニルモノマーを意味する。また、加水分解性ビニルモノマー（ａ２）における加水分解性とは、例えば、水及び必要により触媒（酸又は塩基等）の作用により加水分解され、水溶性になる性質を意味する。加水分解性ビニルモノマー（ａ２）の加水分解は、重合中、重合後及びこれらの両方のいずれで行っても良いが、得られる吸水性樹脂粒子の吸収性能の観点から、重合後が好ましい。 A vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) by hydrolysis [hereinafter, also referred to as a hydrolyzable vinyl monomer (a2). ] Is not particularly limited, and is a known {for example, a vinyl monomer having at least one hydrolyzable substituent which becomes a water-soluble substituent by hydrolysis disclosed in paragraphs 0024 to 0025 of Japanese Patent Application Laid-Open No. 3648553, JP. At least one hydrolyzable substituent [1,3-oxo-2-oxapropylene (-CO-O-CO-) group, acyl group and cyano) disclosed in paragraphs 0052 to 0055 of JP-A-2005-75982. A vinyl monomer having a [group, etc.]} can be used. The water-soluble vinyl monomer is a concept well known to those skilled in the art, but when expressed using a quantity, it means, for example, a vinyl monomer that dissolves at least 100 g in 100 g of water at 25 ° C. The hydrolyzable property of the hydrolyzable vinyl monomer (a2) means, for example, the property of being hydrolyzed by the action of water and, if necessary, a catalyst (acid, base, etc.) to become water-soluble. The hydrolyzable vinyl monomer (a2) may be hydrolyzed during or after the polymerization, or both of them, but it is preferable after the polymerization from the viewpoint of the absorption performance of the obtained water-absorbent resin particles.
これらのうち、吸収性能等の観点から好ましいのは水溶性ビニルモノマー（ａ１）、更に好ましいのは上述のアニオン性ビニルモノマー、カルボキシ（塩）基、スルホ（塩）基、アミノ基、カルバモイル基、アンモニオ基又はモノ−、ジ−若しくはトリ−アルキルアンモニオ基を有するビニルモノマー、更に好ましいのはカルボキシ（塩）基又はカルバモイル基を有するビニルモノマー、特に好ましいのは（メタ）アクリル酸（塩）及び（メタ）アクリルアミド、とりわけ好ましいのは（メタ）アクリル酸（塩）、最も好ましいのはアクリル酸（塩）である。 Of these, the water-soluble vinyl monomer (a1) is preferable from the viewpoint of absorption performance, and the above-mentioned anionic vinyl monomer, carboxy (salt) group, sulfo (salt) group, amino group, and carbamoyl group are more preferable. Vinyl monomers having an ammonio group or a mono-, di- or tri-alkylammonio group, more preferably a vinyl monomer having a carboxy (salt) group or a carbamoyl group, particularly preferably (meth) acrylic acid (salt) and (Meta) acrylamide, especially preferred is (meth) acrylic acid (salt), most preferred is acrylic acid (salt).
なお、「カルボキシ（塩）基」は「カルボキシ基」又は「カルボキシレート基」を意味し、「スルホ（塩）基」は「スルホ基」又は「スルホネート基」を意味する。また、（メタ）アクリル酸（塩）はアクリル酸、アクリル酸塩、メタクリル酸又はメタクリル酸塩を意味し、（メタ）アクリルアミドはアクリルアミド又はメタクリルアミドを意味する。また、塩としては、アルカリ金属（リチウム、ナトリウム及びカリウム等）塩、アルカリ土類金属（マグネシウム及びカルシウム等）塩及びアンモニウム（ＮＨ４）塩等が挙げられる。これらの塩のうち、吸収性能等の観点から、アルカリ金属塩及びアンモニウム塩が好ましく、更に好ましいのはアルカリ金属塩、特に好ましいのはナトリウム塩である。 In addition, "carboxy (salt) group" means "carboxy group" or "carboxylate group", and "sulfo (salt) group" means "sulfo group" or "sulfonate group". Further, (meth) acrylic acid (salt) means acrylic acid, acrylate, methacrylic acid or methacrylic acid, and (meth) acrylamide means acrylamide or methacrylamide. Examples of the salt include alkali metal (lithium, sodium, potassium, etc.) salt, alkaline earth metal (magnesium, calcium, etc.) salt, ammonium (NH 4 ) salt, and the like. Among these salts, an alkali metal salt and an ammonium salt are preferable from the viewpoint of absorption performance and the like, an alkali metal salt is more preferable, and a sodium salt is particularly preferable.
水溶性ビニルモノマー（ａ１）又は加水分解性ビニルモノマー（ａ２）のいずれかを構成単位とする場合、それぞれ１種を単独で構成単位としてもよく、また、必要により２種以上を構成単位としても良い。また、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）を構成単位とする場合も同様である。また、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）を構成単位とする場合、これらの含有モル比［（ａ１）／（ａ２）］は、７５／２５〜９９／１が好ましく、更に好ましくは８５／１５〜９５／５、特に好ましくは９０／１０〜９３／７、最も好ましくは９１／９〜９２／８である。この範囲内であると、吸収性能が更に良好となる。 When either the water-soluble vinyl monomer (a1) or the hydrolyzable vinyl monomer (a2) is used as a constituent unit, one of each may be used alone as a constituent unit, or two or more thereof may be used as a constituent unit, if necessary. good. The same applies to the case where the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as constituent units. When the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as constituent units, the molar ratio [(a1) / (a2)] of these is preferably 75/25 to 99/1. It is more preferably 85/15 to 95/5, particularly preferably 90/10 to 93/7, and most preferably 91/9 to 92/8. Within this range, the absorption performance is further improved.
重合体（Ａ）の構成単位として、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）の他に、これらと共重合可能なその他のビニルモノマー（ａ３）を構成単位とすることができる。その他のビニルモノマー（ａ３）は１種を単独で用いても、２種以上を併用してもよい。 As the constituent unit of the polymer (A), in addition to the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), another vinyl monomer (a3) copolymerizable with these may be used as the constituent unit. it can. As the other vinyl monomer (a3), one type may be used alone, or two or more types may be used in combination.
その他のビニルモノマー（ａ３）としては特に限定はなく、公知（例えば、特許第３６４８５５３号公報の００２８〜００２９段落に開示されている疎水性ビニルモノマー、特開２００３−１６５８８３号公報の００２５段落及び特開２００５−７５９８２号公報の００５８段落に開示されているビニルモノマー等）の疎水性ビニルモノマー等が使用でき、具体的には例えば下記の（ｉ）〜（ｉｉｉ）のビニルモノマー等が使用できる。
（ｉ）炭素数８〜３０の芳香族エチレン性モノマー
スチレン、α−メチルスチレン、ビニルトルエン及びヒドロキシスチレン等のスチレン、並びにビニルナフタレン及びジクロルスチレン等のスチレンのハロゲン置換体等。
（ｉｉ）炭素数２〜２０の脂肪族エチレン性モノマー
アルケン（エチレン、プロピレン、ブテン、イソブチレン、ペンテン、ヘプテン、ジイソブチレン、オクテン、ドデセン及びオクタデセン等）；並びにアルカジエン（ブタジエン及びイソプレン等）等。
（ｉｉｉ）炭素数５〜１５の脂環式エチレン性モノマー
モノエチレン性不飽和モノマー（ピネン、リモネン及びインデン等）；並びにポリエチレン性ビニルモノマー［シクロペンタジエン、ビシクロペンタジエン及びエチリデンノルボルネン等］等。
The other vinyl monomer (a3) is not particularly limited, and is known (for example, the hydrophobic vinyl monomer disclosed in paragraphs 0028 to 0029 of Japanese Patent No. 3648553, paragraph 0025 of Japanese Patent Application Laid-Open No. 2003-165883, and the present invention. Hydrophobic vinyl monomers (such as the vinyl monomers disclosed in paragraph 0058 of JP-A-2005-75982) can be used, and specifically, for example, the following vinyl monomers (i) to (iii) can be used.
(I) Aromatic ethylenic monomer having 8 to 30 carbon atoms Styrene such as styrene, α-methylstyrene, vinyltoluene and hydroxystyrene, halogen-substituted styrene such as vinylnaphthalene and dichlorostyrene and the like.
(Ii) Alkenes (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkaziene (butadiene, isoprene, etc.) and the like.
(Iii) Alicyclic ethylenic monomer having 5 to 15 carbon atoms Monoethylenically unsaturated monomer (pinene, limonene, inden, etc.); and polyethylene vinyl monomer [cyclopentadiene, bicyclopentadiene, ethylidene norbornene, etc.] and the like.
その他のビニルモノマー（ａ３）単位の含有量（モル％）は、吸収性能等の観点から、水溶性ビニルモノマー（ａ１）単位及び加水分解性ビニルモノマー（ａ２）単位の合計モル数に基づいて、０〜５が好ましく、更に好ましくは０〜３、特に好ましくは０〜２、とりわけ好ましくは０〜１．５であり、吸収性能等の観点から、その他のビニルモノマー（ａ３）単位の含有量が０モル％であることが最も好ましい。 The content (mol%) of the other vinyl monomer (a3) unit is based on the total number of moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit from the viewpoint of absorption performance and the like. The content is preferably 0 to 5, more preferably 0 to 3, particularly preferably 0 to 2, particularly preferably 0 to 1.5, and the content of other vinyl monomer (a3) units is high from the viewpoint of absorption performance and the like. Most preferably, it is 0 mol%.
重合体（Ａ）は必要に応じて、内部架橋剤による架橋を行っても良い。内部架橋剤としては特に限定はなく公知（例えば、特許第３６４８５５３号公報の００３１〜００３４段落に開示されているエチレン性不飽和基を２個以上有する架橋剤、水溶性置換基と反応し得る官能基を少なくとも１個有してかつ少なくとも１個のエチレン性不飽和基を有する架橋剤及び水溶性置換基と反応し得る官能基を少なくとも２個有する架橋剤、特開２００３−１６５８８３号公報の００２８〜００３１段落に開示されているエチレン性不飽和基を２個以上有する架橋剤、エチレン性不飽和基と反応性官能基とを有する架橋剤及び反応性置換基を２個以上有する架橋剤、特開２００５−７５９８２号公報の００５９段落に開示されている架橋性ビニルモノマー並びに特開２００５−９５７５９号公報の００１５〜００１６段落に開示されている架橋性ビニルモノマー）の架橋剤等が使用できる。これらのうち、吸収性能等の観点から、エチレン性不飽和基を２個以上有する架橋剤が好ましく、更に好ましいのはトリアリルシアヌレート、トリアリルイソシアヌレート及び炭素数２〜４０のポリオールのポリ（メタ）アリルエーテル、特に好ましいのはトリアリルシアヌレート、トリアリルイソシアヌレート、テトラアリロキシエタン、ポリエチレングリコールジアリルエーテル及びペンタエリスリトールトリアリルエーテル、最も好ましいのはペンタエリスリトールトリアリルエーテルである。内部架橋剤は１種を単独で用いても、２種以上を併用してもよい。 The polymer (A) may be crosslinked with an internal crosslinking agent, if necessary. The internal cross-linking agent is not particularly limited and is known (for example, a cross-linking agent having two or more ethylenically unsaturated groups disclosed in paragraphs 0031 to 0034 of Japanese Patent No. 36485553, a functional group capable of reacting with a water-soluble substituent. A cross-linking agent having at least one group and having at least one ethylenically unsaturated group and a cross-linking agent having at least two functional groups capable of reacting with a water-soluble substituent, 0028 of JP-A-2003-165883 A cross-linking agent having two or more ethylenically unsaturated groups, a cross-linking agent having an ethylenically unsaturated group and a reactive functional group, and a cross-linking agent having two or more reactive substituents disclosed in paragraphs 0031. The cross-linking agent of the cross-linking vinyl monomer disclosed in paragraph 0059 of Japanese Patent Application Laid-Open No. 2005-75982 and the cross-linking vinyl monomer disclosed in paragraphs 0015 to 0016 of JP-A-2005-59559 can be used. Of these, a cross-linking agent having two or more ethylenically unsaturated groups is preferable from the viewpoint of absorption performance and the like, and more preferable is a poly (triallyl cyanurate, triallyl isocyanurate, and a polyol having 2 to 40 carbon atoms). Meta) Allyl ethers, particularly preferred are triallyl cyanurate, triallyl isocyanurate, tetraallyloxyethane, polyethylene glycol diallyl ether and pentaerythritol triallyl ether, most preferably pentaerythritol triallyl ether. One type of internal cross-linking agent may be used alone, or two or more types may be used in combination.
重合体（Ａ）の重合方法としては、水溶液重合（断熱重合、薄膜重合及び噴霧重合法等；特開昭５５−１３３４１３号公報等）や、公知の懸濁重合方法や逆相懸濁重合（特公昭５４−３０７１０号公報、特開昭５６−２６９０９号公報及び特開平１−５８０８号公報等）が挙げられる。 Examples of the polymerization method of the polymer (A) include aqueous solution polymerization (adiabatic polymerization, thin film polymerization, spray polymerization, etc.; JP-A-55-133413, etc.), known suspension polymerization methods, and reverse phase suspension polymerization ( Japanese Patent Application Laid-Open No. 54-30710, Japanese Patent Application Laid-Open No. 56-26909, Japanese Patent Application Laid-Open No. 1-5808, etc.) can be mentioned.
水溶液重合を行う場合、水と有機溶媒とを含む混合溶媒を使用することができ、有機溶媒としては、メタノール、エタノール、ｎ−プロピルアルコール、イソプロピルアルコール、ｎ−ブタノール、イソブチルアルコール、ｔ−ブチルアルコール、イソペンチルアルコール、アセトン、メチルエチルケトン、Ｎ，Ｎ−ジメチルホルムアミド、ジメチルスルホキシド及びこれらの２種以上の混合物を挙げられる。
有機溶媒の使用量（重量％）は、水の重量を基準として４０以下が好ましく、更に好ましくは３０以下である。
When performing aqueous solution polymerization, a mixed solvent containing water and an organic solvent can be used, and the organic solvent includes methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutyl alcohol, and t-butyl alcohol. , Isopentyl alcohol, acetone, methyl ethyl ketone, N, N-dimethylformamide, dimethyl sulfoxide and mixtures of two or more thereof.
The amount (% by weight) of the organic solvent used is preferably 40 or less, more preferably 30 or less, based on the weight of water.
懸濁重合法又は逆相懸濁重合法をとる場合は、従来公知の分散剤又は界面活性剤の存在下に重合を行っても良い。また、逆相懸濁重合法の場合、キシレン、ノルマルヘキサン及びノルマルヘプタン等の炭化水素系溶媒を使用して重合を行うことができる。 When the suspension polymerization method or the reverse phase suspension polymerization method is adopted, the polymerization may be carried out in the presence of a conventionally known dispersant or surfactant. Further, in the case of the reverse phase suspension polymerization method, the polymerization can be carried out using a hydrocarbon solvent such as xylene, normal hexane and normal heptane.
重合に開始剤を用いる場合、ラジカル重合用開始剤が使用可能であり、例えば、アゾ化合物［アゾビスイソブチロニトリル、アゾビスシアノ吉草酸及び２，２’−アゾビス（２−アミジノプロパン）ハイドロクロライド等］、無機過酸化物（過酸化水素、過硫酸アンモニウム、過硫酸カリウム及び過硫酸ナトリウム等）、有機過酸化物［過酸化ベンゾイル、ジ−ｔ−ブチルパーオキサイド、クメンヒドロパーオキサイド、コハク酸パーオキサイド及びジ（２−エトキシエチル）パーオキシジカーボネート等］及びレドックス触媒（アルカリ金属の亜硫酸塩又は重亜硫酸塩、亜硫酸アンモニウム、重亜硫酸アンモニウム及びアスコルビン酸等の還元剤とアルカリ金属の過硫酸塩、過硫酸アンモニウム、過酸化水素及び有機過酸化物等の酸化剤との組み合わせよりなるもの）等が挙げられる。これらの触媒は、単独で使用してもよく、これらの２種以上を併用しても良い。
ラジカル重合開始剤の使用量（重量％）は、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）の、その他のビニルモノマー（ａ３）を用いる場合は（ａ１）〜（ａ３）の、合計重量に基づいて、０．０００５〜５が好ましく、更に好ましくは０．００１〜２である。
When an initiator is used for polymerization, an initiator for radical polymerization can be used, for example, azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid and 2,2'-azobis (2-amidinopropane) hydrogen peroxide, etc. ], Inorganic peroxides (hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.), organic peroxides [benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinate peroxide, etc. And di (2-ethoxyethyl) peroxydicarbonate, etc.] and redox catalysts (alkali metal sulfites or peroxides, reducing agents such as ammonium sulfite, ammonium persulfate, ascorbic acid, etc. and alkali metal persulfates, hydrogen peroxide, etc. (Combined with an oxidizing agent such as ammonium sulfate, hydrogen peroxide and organic peroxide) and the like. These catalysts may be used alone or in combination of two or more of them.
The amount (% by weight) of the radical polymerization initiator used is the same as that of the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), and (a1) to (a3) when the other vinyl monomer (a3) is used. , 0.0005 to 5, more preferably 0.001 to 2, based on the total weight.
重合時には、必要に応じて連鎖移動剤に代表される重合コントロール剤を併用しても良く、これらの具体例としては、次亜リン酸ナトリウム、亜リン酸ナトリウム、アルキルメルカプタン類、ハロゲン化アルキル類、チオカルボニル化合物類等が挙げられる。これらの重合コントロール剤は、単独で使用してもよく、これらの２種以上を併用しても良い。
重合コントロール剤の使用量（重量％）は、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）の、その他のビニルモノマー（ａ３）を用いる場合は（ａ１）〜（ａ３）の、合計重量に基づいて、０．０００５〜５が好ましく、更に好ましくは０．００１〜２である。
At the time of polymerization, a polymerization control agent typified by a chain transfer agent may be used in combination as needed, and specific examples thereof include sodium hypophosphite, sodium phosphite, alkyl mercaptans, and alkyl halides. , Thiocarbonyl compounds and the like. These polymerization control agents may be used alone or in combination of two or more of them.
The amount (% by weight) of the polymerization control agent used is the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), and when other vinyl monomers (a3) are used, the amounts (a1) to (a3) are as follows. Based on the total weight, 0.0005-5 is preferable, and 0.001-2 is more preferable.
重合開始温度は、使用する触媒の種類によって適宜調整することができるが、０〜１００℃が好ましく、更に好ましくは２〜８０℃である。 The polymerization initiation temperature can be appropriately adjusted depending on the type of catalyst used, but is preferably 0 to 100 ° C, more preferably 2 to 80 ° C.
重合に溶媒（有機溶媒及び水等）を使用する場合、重合後に溶媒を留去することが好ましい。溶媒に有機溶媒を含む場合、留去後の有機溶媒の含有量（重量％）は、重合体（Ａ）の重量に基づいて、０〜１０が好ましく、更に好ましくは０〜５、特に好ましくは０〜３、最も好ましくは０〜１である。この範囲であると、吸水性樹脂粒子の吸収性能が更に良好となる。 When a solvent (organic solvent, water, etc.) is used for the polymerization, it is preferable to distill off the solvent after the polymerization. When the solvent contains an organic solvent, the content (% by weight) of the organic solvent after distillation is preferably 0 to 10, more preferably 0 to 5, and particularly preferably 0 to 5, based on the weight of the polymer (A). It is 0 to 3, most preferably 0 to 1. Within this range, the absorption performance of the water-absorbent resin particles is further improved.
溶媒に水を含む場合、留去後の水分（重量％）は、重合体（Ａ）の重量に基づいて、０〜２０が好ましく、更に好ましくは１〜１０、特に好ましくは２〜９、最も好ましくは３〜８である。この範囲であると、吸収性能が更に良好となる。 When water is contained in the solvent, the water content (% by weight) after distillation is preferably 0 to 20, more preferably 1 to 10, particularly preferably 2 to 9, based on the weight of the polymer (A). It is preferably 3 to 8. Within this range, the absorption performance is further improved.
重合体（Ａ）は、水溶性ビニルモノマー（ａ１）及び／又は加水分解性ビニルモノマー（ａ２）を必須構成成分とする単量体組成物を重合することにより得ることができるが、重合方法として好ましいのは有機溶媒等を使用する必要がなく生産コスト面で有利な水溶液重合法であり、更に好ましいのは、保水量が大きく、且つ水可溶性成分量の少ない水性液体吸収性樹脂が得られ、重合時の温度コントロールが不要な水溶液断熱重合法が最も好ましい。 The polymer (A) can be obtained by polymerizing a monomer composition containing a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) as essential constituents, as a polymerization method. An aqueous solution polymerization method that does not require the use of an organic solvent or the like and is advantageous in terms of production cost is preferable, and an aqueous liquid-absorbable resin having a large water retention amount and a small amount of water-soluble components can be obtained. The aqueous solution adiabatic polymerization method, which does not require temperature control during polymerization, is most preferable.
前記の重合方法により含水ゲル状物（以下、含水ゲルと略記する）を得ることができ、必要に応じて更に含水ゲルを乾燥した粒子状重合体の表面を架橋することによって重合体（Ａ）を得ることもできる。
水溶性ビニルモノマー（ａ１）としてアクリル酸やメタクリル酸等の酸基含有モノマーを用いる場合、含水ゲルを塩基で中和しても良い。酸基の中和度は、５０〜８０モル％であることが好ましい。中和度が５０モル％未満の場合、得られる含水ゲル重合体の粘着性が高くなり、製造時及び使用時の作業性が悪化する場合がある。更に得られる水性液体吸収性樹脂の保水量が低下する場合がある。一方、中和度が８０％を超える場合、得られた樹脂のｐＨが高くなり人体の皮膚に対する安全性が懸念される場合がある。
なお、中和は、吸水性樹脂粒子の製造において、単量体組成物の重合以降のいずれの段階で行ってもよく、例えば、含水ゲルの状態で中和する方法が好ましい例として例示される。
中和する塩基としては、水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物や、炭酸ナトリウム、炭酸水素ナトリウム、炭酸カリウム等のアルカリ金属炭酸塩を使用できる。
A hydrogel (hereinafter abbreviated as hydrogel) can be obtained by the above polymerization method, and if necessary, the polymer (A) is further crosslinked with the surface of the dried particulate polymer. You can also get.
When an acid group-containing monomer such as acrylic acid or methacrylic acid is used as the water-soluble vinyl monomer (a1), the hydrogel may be neutralized with a base. The degree of neutralization of the acid group is preferably 50 to 80 mol%. When the degree of neutralization is less than 50 mol%, the adhesiveness of the obtained hydrogel polymer becomes high, and the workability during production and use may deteriorate. Further, the water retention amount of the obtained aqueous liquid absorbent resin may decrease. On the other hand, when the degree of neutralization exceeds 80%, the pH of the obtained resin becomes high, and there is a concern about the safety of the obtained resin on the human skin.
The neutralization may be carried out at any stage after the polymerization of the monomer composition in the production of the water-absorbent resin particles, and for example, a method of neutralizing in the state of a hydrogel is exemplified as a preferable example. ..
As the base to be neutralized, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate, sodium hydrogencarbonate and potassium carbonate can be used.
重合によって得られる含水ゲルは、乾燥前に必要に応じて細断することができる。細断後のゲルの大きさ（最長径）は５０μｍ〜１０ｃｍが好ましく、更に好ましくは１００μｍ〜２ｃｍ、特に好ましくは１ｍｍ〜１ｃｍである。この範囲であると、乾燥工程での乾燥性が更に良好となる。 The hydrogel obtained by polymerization can be shredded as needed before drying. The size (longest diameter) of the gel after shredding is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, and particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying step is further improved.
細断は、公知の方法で行うことができ、細断装置（例えば、ベックスミル、ラバーチョッパ、ファーマミル、ミンチ機、衝撃式粉砕機及びロール式粉砕機）等を使用して細断できる。 Shredding can be performed by a known method, and can be shredded using a shredding device (for example, a Beck's mill, a rubber chopper, a pharma mill, a minced machine, an impact type crusher, and a roll type crusher).
なお、有機溶媒の含有量及び水分量は、赤外水分測定器［（株）ＫＥＴＴ社製ＪＥ４００等：１２０±５℃、３０分、加熱前の雰囲気湿度５０±１０％ＲＨ、ランプ仕様１００Ｖ、４０Ｗ］により加熱したときの測定試料の重量減量から求められる。 The content and water content of the organic solvent are determined by an infrared moisture measuring device [JE400 manufactured by KETT Co., Ltd .: 120 ± 5 ° C., 30 minutes, atmospheric humidity 50 ± 10% RH before heating, lamp specification 100 V, It is obtained from the weight loss of the measurement sample when heated by [40 W].
含水ゲルの溶媒（水を含む。）を留去し、乾燥する方法としては、８０〜２３０℃の温度の熱風で留去（乾燥）する方法、１００〜２３０℃に加熱されたドラムドライヤー等による薄膜乾燥法、（加熱）減圧乾燥法、凍結乾燥法、赤外線による乾燥法、デカンテーション及び濾過等が適用できる。また、乾燥時間については特に限定されないが、過乾燥によるゲルの劣化の観点から、０〜３時間が好ましく、０〜３０分が更に好ましい。 As a method of distilling off the solvent (including water) of the hydrogel and drying it, a method of distilling off (drying) with hot air at a temperature of 80 to 230 ° C., a drum dryer heated to 100 to 230 ° C., or the like is used. Thin film drying method, (heating) vacuum drying method, freeze drying method, infrared drying method, decantation, filtration and the like can be applied. The drying time is not particularly limited, but from the viewpoint of gel deterioration due to overdrying, 0 to 3 hours is preferable, and 0 to 30 minutes is more preferable.
重合体（Ａ）は、必要により粉砕、分級によって形状、粒度を制御することができる。重合体（Ａ）の形状については、不定形破砕状、リン片状、パール状及び米粒状等が挙げられる。これらのうち、紙おむつ用途等での繊維状物とのからみが良く、繊維状物からの脱落の心配がないという観点から、不定形破砕状が好ましい。
粉砕方法については、特に限定はなく、粉砕装置（例えば、ハンマー式粉砕機、衝撃式粉砕機、ロール式粉砕機及びシェット気流式粉砕機）等が使用できる。粉砕された重合体は、必要によりふるい分け等により粒度調整できる。
The shape and particle size of the polymer (A) can be controlled by pulverization and classification, if necessary. Examples of the shape of the polymer (A) include amorphous crushed form, phosphorus fragment form, pearl form and rice granule. Of these, the amorphous crushed form is preferable from the viewpoint of good entanglement with the fibrous material for use in disposable diapers and the like and no fear of falling off from the fibrous material.
The crushing method is not particularly limited, and a crushing device (for example, a hammer type crusher, an impact type crusher, a roll type crusher, a shet airflow type crusher) or the like can be used. The particle size of the pulverized polymer can be adjusted by sieving or the like, if necessary.
重合体（Ａ）の重量平均粒子径（μｍ）は、１００〜８００が好ましく、更に好ましくは２００〜７００、次に好ましくは２５０〜６００、特に好ましくは３００〜５００、最も好ましくは３５０〜４５０である。この範囲であると、吸水性樹脂粒子の耐壊れ性、吸収性能が更に良好となる。
また、吸収性能の観点から、重合体（Ａ）の合計重量に占める１０６μｍ以下（好ましくは１５０μｍ以下）の微粒子の含有率（重量％）は３以下が好ましく、更に好ましくは１以下である。微粒子の含有量は、上記の重量平均粒子径を求める際に作成するグラフを用いて求めることができる。
The weight average particle size (μm) of the polymer (A) is preferably 100 to 800, more preferably 200 to 700, then preferably 250 to 600, particularly preferably 300 to 500, and most preferably 350 to 450. is there. Within this range, the breakage resistance and absorption performance of the water-absorbent resin particles are further improved.
From the viewpoint of absorption performance, the content (% by weight) of fine particles of 106 μm or less (preferably 150 μm or less) in the total weight of the polymer (A) is preferably 3 or less, and more preferably 1 or less. The content of the fine particles can be determined by using the graph created when determining the weight average particle diameter described above.
重量平均粒子径は、ロータップ試験篩振とう機及び標準ふるい（ＪＩＳ Ｚ８８０１−１：２００６）を用いて、ペリーズ・ケミカル・エンジニアーズ・ハンドブック第６版（マックグローヒル・ブック・カンバニー、１９８４、２１頁）に記載の方法で測定される。すなわち、ＪＩＳ標準ふるいを、上から１０００μｍ、８５０μｍ、７１０μｍ、５００μｍ、４２５μｍ、３５５μｍ、２５０μｍ、１５０μｍ、１２５μｍ、７５μｍ及び４５μｍ、並びに受け皿、の順等に組み合わせる。最上段のふるいに測定粒子の約５０ｇを入れ、ロータップ試験篩振とう機で５分間振とうさせる。各ふるい及び受け皿上の測定粒子の重量を秤量し、その合計を１００重量％として各ふるい上の粒子の重量分率を求め、この値を対数確率紙［横軸がふるいの目開き（粒子径）、縦軸が重量分率］にプロットした後、各点を結ぶ線を引き、重量分率が５０重量％に対応する粒子径を求め、これを重量平均粒子径とする。 The weight average particle size is determined by using a low-tap test sieve shaker and a standard sieve (JIS Z8801-1: 2006), Perry's Chemical Engineers Handbook 6th Edition (McGlow Hill Book Canvas, 1984, 21). Page) is measured by the method described. That is, the JIS standard sieves are combined in the order of 1000 μm, 850 μm, 710 μm, 500 μm, 425 μm, 355 μm, 250 μm, 150 μm, 125 μm, 75 μm and 45 μm, and the saucer from the top. Place about 50 g of the measurement particles in the uppermost sieve and shake with a low-tap test sieve shaker for 5 minutes. Weigh the measured particles on each sieve and saucer, and take the total as 100% by weight to obtain the weight fraction of the particles on each sieve, and use this value as the logarithmic probability paper [the horizontal axis is the opening of the sieve (particle size). ), The vertical axis is the weight fraction], then draw a line connecting each point to obtain the particle size corresponding to the weight fraction of 50% by weight, and use this as the weight average particle diameter.
なお、重合体（Ａ）は、その性能を損なわない範囲で残留溶媒や残存架橋成分等の他の成分を多少含んでも良い。 The polymer (A) may contain some other components such as a residual solvent and a residual cross-linking component as long as its performance is not impaired.
本発明の重合体（Ａ）は、その表面が表面架橋剤（ｄ）により架橋された構造を有することができる。重合体（Ａ）の表面を架橋することにより吸水性樹脂粒子のゲル強度を向上させることができ、吸水性樹脂粒子の望ましい保水量と荷重下における吸収量とを満足させることができる。表面架橋剤（ｄ）としては、公知（特開昭５９−１８９１０３号公報に記載の多価グリシジル化合物、多価アミン、多価アジリジン化合物及び多価イソシアネート化合物等、特開昭５８−１８０２３３号公報及び特開昭６１−１６９０３号公報の多価アルコール、特開昭６１−２１１３０５号公報及び特開昭６１−２５２２１２号公報に記載のシランカップリング剤、特表平５−５０８４２５号公報に記載のアルキレンカーボネート、特開平１１−２４０９５９号公報に記載の多価オキサゾリン化合物並びに特開昭５１−１３６５８８号公報及び特開昭６１−２５７２３５号公報に記載の多価金属等の表面架橋剤等が使用できる。これらの表面架橋剤のうち、経済性及び吸収特性の観点から、多価グリシジル化合物、多価アルコール及び多価アミンが好ましく、更に好ましいのは多価グリシジル化合物及び多価アルコール、特に好ましいのは多価グリシジル化合物、最も好ましいのはエチレングリコールジグリシジルエーテルである。表面架橋剤は１種を単独で用いても良いし、２種以上を併用しても良い。２種以上を併用して用いる場合は、吸水性樹脂粒子の耐壊れ性の観点から、表面架橋剤同士が反応性を有しない２種を選定することが好ましい。 The polymer (A) of the present invention can have a structure in which the surface thereof is crosslinked by the surface cross-linking agent (d). By cross-linking the surface of the polymer (A), the gel strength of the water-absorbent resin particles can be improved, and the desired water-retaining amount of the water-absorbent resin particles and the absorption amount under load can be satisfied. Examples of the surface cross-linking agent (d) include polyvalent glycidyl compounds, polyvalent amines, polyvalent aziridine compounds and polyhydric isocyanate compounds described in JP-A-59-189103, and JP-A-58-180233. And the polyhydric alcohol of JP-A-61-16903, the silane coupling agent described in JP-A-61-221305 and JP-A-61-252212, and described in JP-A-5-508425. An alkylene carbonate, a polyvalent oxazoline compound described in JP-A-11-240959, and a surface cross-linking agent such as a polyvalent metal described in JP-A-51-136588 and JP-A-61-257235 can be used. Of these surface cross-linking agents, polyhydric glycidyl compounds, polyhydric alcohols and polyhydric amines are preferable, and polyhydric glycidyl compounds and polyhydric alcohols are particularly preferable, and polyhydric alcohols are particularly preferable, from the viewpoint of economic efficiency and absorption characteristics. A polyvalent glycidyl compound, most preferably an ethylene glycol diglycidyl ether. One type of surface cross-linking agent may be used alone, or two or more types may be used in combination. Two or more types may be used in combination. In this case, from the viewpoint of the breakage resistance of the water-absorbent resin particles, it is preferable to select two types in which the surface cross-linking agents do not have a reactivity with each other.
表面架橋剤（ｄ）の使用量（重量％）は、表面架橋剤の種類、架橋させる条件、目標とする性能等により種々変化させることができるため特に限定はないが、吸収特性の観点等から、吸水性樹脂１００重量部に対して、０．００１〜３が好ましく、更に好ましくは０．００５〜２、特に好ましくは０．０１〜１．５である。 The amount (% by weight) of the surface cross-linking agent (d) used is not particularly limited because it can be variously changed depending on the type of the surface cross-linking agent, the conditions for cross-linking, the target performance, etc., but from the viewpoint of absorption characteristics and the like. It is preferably 0.001 to 3 and more preferably 0.005 to 2, particularly preferably 0.01 to 1.5, based on 100 parts by weight of the water-absorbent resin.
重合体（Ａ）の表面架橋は、重合体（Ａ）と表面架橋剤（ｄ）とを混合し、必要に応じて加熱することで行うことができる。重合体（Ａ）と表面架橋剤（ｄ）との混合方法としては、円筒型混合機、スクリュー型混合機、スクリュー型押出機、タービュライザー、ナウター型混合機、双腕型ニーダー、流動式混合機、Ｖ型混合機、ミンチ混合機、リボン型混合機、流動式混合機、気流型混合機、回転円盤型混合機、コニカルブレンダー及びロールミキサー等の混合装置を用いて重合体（Ａ）と表面架橋剤（ｄ）とを均一混合する方法が挙げられる。この際、表面架橋剤（ｄ）は、水及び／又は任意の溶剤で希釈して使用しても良い。 The surface cross-linking of the polymer (A) can be carried out by mixing the polymer (A) and the surface cross-linking agent (d) and heating as necessary. Examples of the mixing method of the polymer (A) and the surface cross-linking agent (d) include a cylindrical mixer, a screw type mixer, a screw type extruder, a turbulizer, a Nauter type mixer, a double-armed kneader, and a fluid type. Polymer (A) using a mixer such as a mixer, V-type mixer, minced mixer, ribbon-type mixer, fluid-type mixer, airflow-type mixer, rotary disk-type mixer, conical blender, and roll mixer. And a method of uniformly mixing the surface cross-linking agent (d) can be mentioned. At this time, the surface cross-linking agent (d) may be diluted with water and / or any solvent before use.
重合体（Ａ）と表面架橋剤（ｄ）とを混合する際の温度は特に限定されないが、１０〜１５０℃が好ましく、更に好ましくは２０〜１００℃、特に好ましくは２５〜８０℃である。 The temperature at which the polymer (A) and the surface cross-linking agent (d) are mixed is not particularly limited, but is preferably 10 to 150 ° C, more preferably 20 to 100 ° C, and particularly preferably 25 to 80 ° C.
重合体（Ａ）と表面架橋剤（ｄ）とを混合した後、加熱処理を行うことで表面架橋された重合体（Ａ）を得ることができる。加熱温度は、樹脂粒子の耐壊れ性の観点から好ましくは１００〜１８０℃、更に好ましくは１１０〜１７５℃、特に好ましくは１２０〜１７０℃である。１８０℃以下の加熱であれば蒸気を利用した間接加熱が可能であり設備上有利であり、１００℃未満の加熱温度では吸収性能が悪くなる場合がある。また、加熱時間は加熱温度により適宜設定することができるが、吸収性能の観点から、好ましくは５〜６０分、更に好ましくは１０〜４０分である。表面架橋された重合体（Ａ）を、最初に用いた表面架橋剤と同種又は異種の表面架橋剤を用いて、更に表面架橋することも可能である。 The surface-crosslinked polymer (A) can be obtained by mixing the polymer (A) and the surface cross-linking agent (d) and then heat-treating the polymer (A). The heating temperature is preferably 100 to 180 ° C., more preferably 110 to 175 ° C., and particularly preferably 120 to 170 ° C. from the viewpoint of fracture resistance of the resin particles. Indirect heating using steam is possible if the heating is 180 ° C. or lower, which is advantageous in terms of equipment, and if the heating temperature is lower than 100 ° C., the absorption performance may deteriorate. The heating time can be appropriately set depending on the heating temperature, but is preferably 5 to 60 minutes, more preferably 10 to 40 minutes from the viewpoint of absorption performance. It is also possible to further surface-crosslink the surface-crosslinked polymer (A) by using a surface-crosslinking agent of the same type or different type as the surface-crosslinking agent used first.
重合体（Ａ）は、必要により篩別して粒度調整される。得られた粒子の平均粒経は、好ましくは１００〜６００μｍ、更に好ましくは２００〜５００μｍである。微粒子の含有量は少ない方が好ましく、１００μｍ以下の粒子の含有量は３重量％以下であることが好ましく、１５０μｍ以下の粒子の含有量が３重量％以下であることが更に好ましい。 If necessary, the polymer (A) is sieved to adjust the particle size. The average grain diameter of the obtained particles is preferably 100 to 600 μm, more preferably 200 to 500 μm. The content of the fine particles is preferably small, the content of the particles of 100 μm or less is preferably 3% by weight or less, and the content of the particles of 150 μm or less is more preferably 3% by weight or less.
本発明の吸水性樹脂粒子において、重合体（Ａ）は、更に疎水性物質で処理してもよく、疎水性物質で処理する方法としては、特開２０１３−２３１１９９等に記載の方法を利用出来る。 In the water-absorbent resin particles of the present invention, the polymer (A) may be further treated with a hydrophobic substance, and as a method for treating with a hydrophobic substance, the method described in JP2013-231199 and the like can be used. ..
本発明の吸水性樹脂粒子は、多価金属塩（Ｂ）を樹脂粒子表面に有することが好ましい。多価金属塩（Ｂ）は、一分子中に多価金属原子を３個以上含み、多価金属原子としてはカルシウム、マグネシウム、鉄、アルミニウム、コバルト、ニッケル、銅などが挙げられる。一分子中に多価金属原子を３個以上含む多価金属塩（Ｂ）としてはポリ硫酸第二鉄、ポリ塩化アルミニウム、ポリ酢酸アルミニウム、ポリ水酸化アルミニウム、ポリ硫酸ケイ酸アルミニウムなどが挙げられる。これらのうち、ポリ硫酸第二鉄、ポリ塩化アルミニウムが好ましく、ポリ塩化アルミニウムがより好ましい。本発明の吸水性樹脂粒子は、一分子中に多価金属原子を３個以上含む多価金属塩を有することで、吸水後吸水体のひび割れ等を抑制することができる。これは、一分子中に多価金属原子を３個以上含むことによって、ゲルと多点で相互作用し、膨潤後の吸収体の形状保持性が飛躍的に改善すると推定される。 The water-absorbent resin particles of the present invention preferably have a polyvalent metal salt (B) on the surface of the resin particles. The polyvalent metal salt (B) contains three or more polyvalent metal atoms in one molecule, and examples of the polyvalent metal atom include calcium, magnesium, iron, aluminum, cobalt, nickel, and copper. Examples of the polyvalent metal salt (B) containing three or more polyvalent metal atoms in one molecule include ferric polysulfate, polyaluminum chloride, aluminum polyacetate, polyaluminum hydroxide, and aluminum polysilicate silicate. .. Of these, ferric sulfate and polyaluminum chloride are preferable, and polyaluminum chloride is more preferable. By having the polyvalent metal salt containing three or more polyvalent metal atoms in one molecule, the water-absorbent resin particles of the present invention can suppress cracking of the water-absorbent body after water absorption. It is presumed that by containing three or more multivalent metal atoms in one molecule, it interacts with the gel at multiple points, and the shape retention of the absorber after swelling is dramatically improved.
多価金属塩（Ｂ）は、吸水後粒子の耐壊れ性の観点から、吸水性樹脂粒子の重量に対して、０．５〜２０重量％であり、好ましくは１．０〜１０．０重量％、更に好ましくは、１．５〜８．０重量％である。多価金属塩（Ｂ）の含有量が０．５重量％未満の場合は粒子表面が十分に被覆されず、膨潤後の吸収体の形状保持性改善効果が低い。一方、２０重量％を超えるとゲルの膨潤阻害効果が大きく、吸収性能が悪化する。また、多価金属塩（Ｂ）を樹脂粒子表面に有する場合も、樹脂粒子表面に存在する多価金属塩（Ｂ）は、上述の数量範囲であることが好ましい。ここで、樹脂粒子表面とは、表面又は表面近傍を指し、厚さが数十μｍ以下の表層部分又は全体の厚さの１／１０以下の表層部分を意味する。 The polyvalent metal salt (B) is 0.5 to 20% by weight, preferably 1.0 to 10.0% by weight, based on the weight of the water-absorbent resin particles, from the viewpoint of breakage resistance of the particles after water absorption. %, More preferably 1.5 to 8.0% by weight. When the content of the polyvalent metal salt (B) is less than 0.5% by weight, the particle surface is not sufficiently covered, and the effect of improving the shape retention of the absorber after swelling is low. On the other hand, if it exceeds 20% by weight, the gel swelling inhibitory effect is large and the absorption performance deteriorates. Further, even when the polyvalent metal salt (B) is present on the surface of the resin particles, the polyvalent metal salt (B) existing on the surface of the resin particles is preferably in the above-mentioned quantity range. Here, the surface of the resin particles refers to the surface or the vicinity of the surface, and means a surface layer portion having a thickness of several tens of μm or less or a surface layer portion having a thickness of 1/10 or less of the total thickness.
本発明の吸水性樹脂は、重合体（Ａ）と多価金属塩（Ｂ）とを混合することで得ることができる。混合方法としては、円筒型混合機、スクリュー型混合機、スクリュー型押出機、タービュライザー、ナウター型混合機、双腕型ニーダー、流動式混合機、Ｖ型混合機、ミンチ混合機、リボン型混合機、流動式混合機、気流型混合機、回転円盤型混合機、コニカルブレンダー及びロールミキサー等の公知の混合装置を用いて均一混合する方法が挙げられる。 The water-absorbent resin of the present invention can be obtained by mixing the polymer (A) and the polyvalent metal salt (B). As a mixing method, a cylindrical mixer, a screw type mixer, a screw type extruder, a turbulizer, a nouter type mixer, a double-armed kneader, a fluid type mixer, a V type mixer, a minced mixer, and a ribbon type. Examples thereof include a method of uniformly mixing using a known mixing device such as a mixer, a flow type mixer, an air flow type mixer, a rotary disk type mixer, a conical blender and a roll mixer.
重合体（Ａ）と多価金属塩（Ｂ）との混合は、重合体（Ａ）の撹拌下に多価金属塩（Ｂ）を加えることが好ましい。加えられる多価金属塩（Ｂ）は、水及び／又は溶剤と同時に添加しても良い。多価金属塩（Ｂ）を水及び／又は溶剤と同時に添加する場合、多価金属塩（Ｂ）を水及び／若しくは溶剤に溶解した溶液又は多価金属塩（Ｂ）を水及び／若しくは溶剤に分散した分散体を添加することができ、作業性等の観点から溶液を添加することが好ましく、水に溶解した溶液を添加することが更に好ましい。溶液又は分散体を添加する場合、噴霧又は滴下して添加することが好ましい。 For mixing the polymer (A) and the polyvalent metal salt (B), it is preferable to add the polyvalent metal salt (B) under stirring of the polymer (A). The polyvalent metal salt (B) to be added may be added at the same time as water and / or a solvent. When the polyvalent metal salt (B) is added at the same time as water and / or a solvent, a solution in which the polyvalent metal salt (B) is dissolved in water and / or a solvent or a polyvalent metal salt (B) is added to water and / or a solvent. It is possible to add the dispersion dispersed in the water, and it is preferable to add the solution from the viewpoint of workability and the like, and it is more preferable to add the solution dissolved in water. When adding a solution or dispersion, it is preferable to add by spraying or dropping.
多価金属塩（Ｂ）を水に溶解した水溶液を用いる場合、水溶液に含まれる多価金属塩（Ｂ）の含有量は、吸水後吸収体の形状保持性の観点から水溶液の合計重量に対して５〜７０％重量％が好ましく、更に好ましくは１０〜６０重量％である。上記範囲より低濃度の場合は、重合体内部に多価金属塩が浸透し形状保持性が低下し、高濃度の場合は不均一となるため、好ましくない。 When an aqueous solution in which the polyvalent metal salt (B) is dissolved in water is used, the content of the polyvalent metal salt (B) contained in the aqueous solution is based on the total weight of the aqueous solution from the viewpoint of shape retention of the absorber after water absorption. It is preferably 5 to 70% by weight, more preferably 10 to 60% by weight. If the concentration is lower than the above range, the polyvalent metal salt permeates into the polymer and the shape retention property is lowered, and if the concentration is high, it becomes non-uniform, which is not preferable.
溶剤の種類は特に制限されないが、多価アルコール類（エチレングリコール、プロピレングリコール及び１，４−ブタンジオール等）が好適に使用され、溶剤は１種単独で用いても、２種以上を併用してもよい。 The type of solvent is not particularly limited, but polyhydric alcohols (ethylene glycol, propylene glycol, 1,4-butanediol, etc.) are preferably used, and the solvent may be used alone or in combination of two or more. You may.
重合体（Ａ）と多価金属塩（Ｂ）を混合する際の温度は、１００〜１４０℃が好ましく、更に好ましくは１００〜１２０℃である。 The temperature at which the polymer (A) and the polyvalent metal salt (B) are mixed is preferably 100 to 140 ° C, more preferably 100 to 120 ° C.
重合体（Ａ）と多価金属塩（Ｂ）との混合後に加熱する場合、加熱時間は加熱温度により適宜設定することができるが、吸収性能の観点から、好ましくは５〜６０分、更に好ましくは１０〜４０分である。重合体（Ａ）と多価金属塩（Ｂ）とを混合して得られる吸水性樹脂を、最初に用いた多価金属塩と同種又は異種の多価金属塩を用いて、更に表面処理することも可能である。 When heating after mixing the polymer (A) and the polyvalent metal salt (B), the heating time can be appropriately set depending on the heating temperature, but from the viewpoint of absorption performance, it is preferably 5 to 60 minutes, more preferably. Is 10 to 40 minutes. The water-absorbent resin obtained by mixing the polymer (A) and the polyvalent metal salt (B) is further surface-treated with a polyvalent metal salt of the same type or different from the polyvalent metal salt used first. It is also possible.
本発明の吸水性樹脂粒子は、重合体（Ａ）と多価金属塩（Ｂ）との混合後に、篩別して粒度調整して用いても良い。粒度調整して得られた粒子の平均粒経は、好ましくは１００〜６００μｍ、更に好ましくは２００〜５００μｍである。微粒子の含有量は少ない方が好ましく、１００μｍ以下の粒子の含有量は３重量％以下であることが好ましく、１５０μｍ以下の粒子の含有量が３重量％以下であることが更に好ましい。 The water-absorbent resin particles of the present invention may be used after mixing the polymer (A) and the polyvalent metal salt (B) and then sieving to adjust the particle size. The average grain diameter of the particles obtained by adjusting the particle size is preferably 100 to 600 μm, more preferably 200 to 500 μm. The content of the fine particles is preferably small, the content of the particles of 100 μm or less is preferably 3% by weight or less, and the content of the particles of 150 μm or less is more preferably 3% by weight or less.
本発明の吸水性樹脂粒子は、更に水不溶性無機粒子（ｆ）を含んでも良い。水不溶性無機粒子（ｆ）を含むことで吸水性樹脂粒子に含まれる粒子の表面が水不溶性無機粒子（ｆ）で表面処理されることにより、吸水性樹脂粒子の耐ブロッキング性及び通液性が向上する。 The water-absorbent resin particles of the present invention may further contain water-insoluble inorganic particles (f). By including the water-insoluble inorganic particles (f), the surface of the particles contained in the water-absorbent resin particles is surface-treated with the water-insoluble inorganic particles (f), so that the blocking resistance and liquid permeability of the water-absorbent resin particles are improved. improves.
水不溶性無機粒子（ｆ）としては、コロイダルシリカ、フュームドシリカ、クレー及びタルク等が挙げられ、入手の容易性や扱いやすさ、吸収性能の観点から、コロイダルシリカ及びシリカが好ましく、更に好ましいのはコロイダルシリカである。水不溶性無機粒子（ｆ）は１種を単独で用いても良いし、２種以上を併用しても良い。 Examples of the water-insoluble inorganic particles (f) include colloidal silica, fumed silica, clay and talc, and colloidal silica and silica are preferable and further preferable from the viewpoint of availability, ease of handling and absorption performance. Is colloidal silica. One type of water-insoluble inorganic particles (f) may be used alone, or two or more types may be used in combination.
水不溶性無機粒子（ｆ）の使用量（重量部）は、吸収性能の観点から吸水性樹脂１００重量部に対して、０．０１〜５が好ましく、更に好ましくは０．０５〜１、特に好ましくは０．１〜０．５である。 The amount (parts by weight) of the water-insoluble inorganic particles (f) used is preferably 0.01 to 5, more preferably 0.05 to 1, and particularly preferably 0.05 to 1 with respect to 100 parts by weight of the water-absorbent resin from the viewpoint of absorption performance. Is 0.1 to 0.5.
水不溶性無機粒子（ｆ）を含む場合、吸水性樹脂粒子と水不溶性無機粒子（ｆ）とを混合することが好ましく、混合は、前記の多価金属塩（Ｂ）の混合と同様の方法で行うことができ、その条件も同様である。 When the water-insoluble inorganic particles (f) are contained, it is preferable to mix the water-absorbent resin particles and the water-insoluble inorganic particles (f), and the mixing is carried out in the same manner as the mixing of the polyvalent metal salt (B) described above. It can be done, and the conditions are the same.
水不溶性無機粒子（ｆ）を混合した後の吸水性樹脂粒子は、粒度調整して用いてもよく、粒度調整は多価金属塩（Ｂ）を混合して後に行う粒度調整と同様に行うことができ、粒度調整後の粒径も同様である。 The water-absorbent resin particles after mixing the water-insoluble inorganic particles (f) may be used after adjusting the particle size, and the particle size adjustment shall be performed in the same manner as the particle size adjustment performed after mixing the polyvalent metal salt (B). The same applies to the particle size after adjusting the particle size.
本発明の吸水性樹脂粒子は、必要に応じて、添加剤（例えば、公知（特開２００３−２２５５６５号及び特開２００６−１３１７６７号等に記載）の防腐剤、防かび剤、抗菌剤、酸化防止剤、紫外線吸収剤、着色剤、芳香剤、消臭剤、通液性向上剤（例えば、硫酸ナトリウムアルミニウム１２水和物等。）及び有機質繊維状物等）を含むこともできる。これらの添加剤を含有させる場合、添加剤の含有量（重量％）は、重合体（Ａ）の重量に基づいて、０．００１〜１０が好ましく、更に好ましくは０．０１〜５、特に好ましくは０．０５〜１、最も好ましくは０．１〜０．５である。 The water-absorbent resin particles of the present invention are, if necessary, an additive (for example, known (described in JP-A-2003-225565 and JP-A-2006-131767), a preservative, a fungicide, an antibacterial agent, and an oxidation. It may also contain an inhibitor, an ultraviolet absorber, a colorant, a fragrance, a deodorant, a liquid permeability improver (for example, sodium aluminum sulfate dodecahydrate, etc.) and an organic fibrous substance, etc.). When these additives are contained, the content (% by weight) of the additives is preferably 0.001 to 10, more preferably 0.01 to 5, particularly preferably 0.01 to 10, based on the weight of the polymer (A). Is 0.05 to 1, most preferably 0.1 to 0.5.
本発明の製造方法は、前記重合体（Ａ）と、多価金属原子を３個以上含む多価金属塩（Ｂ）の溶液とを混合する工程を有する。重合体（Ａ）と多価金属塩（Ｂ）の溶液とを混合する工程は、重合体（Ａ）と多価金属塩（Ｂ）の溶液とを前記の公知の混合装置を用いて混合することで行うことができる。混合時の温度は、１００〜１４０℃が好ましく、更に好ましくは１００〜１２０℃である。多価金属塩（Ｂ）の溶液とすることにより、重合体（Ａ）と多価金属塩（Ｂ）とを均一に混合でき、品質が安定する。前記重合体（Ａ）の表面を表面架橋剤（ｄ）で架橋した後、前記多価金属塩（Ｂ）の溶液を混合することが好ましい。本発明の製造方法は、本発明の吸水性樹脂粒子を得るのに好適である。 The production method of the present invention includes a step of mixing the polymer (A) with a solution of a multivalent metal salt (B) containing three or more polyvalent metal atoms. In the step of mixing the polymer (A) and the solution of the polyvalent metal salt (B), the solution of the polymer (A) and the polyvalent metal salt (B) is mixed using the above-mentioned known mixing device. Can be done by The temperature at the time of mixing is preferably 100 to 140 ° C, more preferably 100 to 120 ° C. By preparing a solution of the polyvalent metal salt (B), the polymer (A) and the polyvalent metal salt (B) can be uniformly mixed, and the quality is stable. After cross-linking the surface of the polymer (A) with the surface cross-linking agent (d), it is preferable to mix the solution of the polyvalent metal salt (B). The production method of the present invention is suitable for obtaining the water-absorbent resin particles of the present invention.
本発明の吸水性樹脂の含水率は耐壊れ性の観点から１〜１０重量％に制御することが好ましく、更に好ましくは２〜９重量％、特に好ましくは３〜８重量％である。
本発明の吸水性樹脂粒子の見掛け密度（ｇ／ｍｌ）は、０．５２〜０．７０が好ましく、更に好ましくは０．５４〜０．６８、特に好ましくは０．５６〜０．６６である。この範囲であると、吸収性物品の排尿等により膨潤した吸水性樹脂（ゲル）を固定化する機能が更に良好となる。吸水性樹脂粒子の見掛け密度は、ＪＩＳ Ｋ７３６５：１９９９に準拠して、２５℃で測定される。
The water content of the water-absorbent resin of the present invention is preferably controlled to 1 to 10% by weight, more preferably 2 to 9% by weight, and particularly preferably 3 to 8% by weight from the viewpoint of breakage resistance.
The apparent density (g / ml) of the water-absorbent resin particles of the present invention is preferably 0.52 to 0.70, more preferably 0.54 to 0.68, and particularly preferably 0.56 to 0.66. .. Within this range, the function of immobilizing the water-absorbent resin (gel) swollen due to urination of the absorbent article becomes even better. The apparent density of the water-absorbent resin particles is measured at 25 ° C. in accordance with JIS K7365: 1999.
本発明の吸水性樹脂粒子の保水量（ｇ／ｇ）は、後述する方法で測定することができ、形状保持性の観点から、３６以上が好ましく、３７以上が更に好ましく、３８以上がより更に好ましい。また、上限値は、荷重下での吸収量の観点から、５５以下が好ましく、５３以下がさらに好ましく、５１以下がより更に好ましい。保水量は、表面架橋剤（ｄ）の使用量（重量％）で適宜調整することができる。 The water retention amount (g / g) of the water-absorbent resin particles of the present invention can be measured by the method described later, and from the viewpoint of shape retention, 36 or more is preferable, 37 or more is more preferable, and 38 or more is further more preferable. preferable. Further, the upper limit value is preferably 55 or less, more preferably 53 or less, still more preferably 51 or less, from the viewpoint of the amount of absorption under load. The amount of water retained can be appropriately adjusted by the amount (% by weight) of the surface cross-linking agent (d) used.
本発明の吸水性樹脂粒子の荷重下吸収量（ｇ／ｇ）は、後述する方法で測定することができ、吸水性能の観点から、５以上が好ましく、１０以上が更に好ましく、１３以上が特に好ましい。また、上限値は、形状保持性の観点から、３０以下が好ましく、２７以下が更に好ましく、２４以下が特に好ましい。 The amount of water-absorbent resin particles of the present invention absorbed under load (g / g) can be measured by a method described later, and from the viewpoint of water absorption performance, 5 or more is preferable, 10 or more is more preferable, and 13 or more is particularly preferable. preferable. Further, the upper limit value is preferably 30 or less, more preferably 27 or less, and particularly preferably 24 or less from the viewpoint of shape retention.
本発明の吸水性樹脂粒子は、例えば、紙おむつ、生理用ナプキン、失禁パッド、医療用パッド等の衛生材料に用いられる吸収体を構成するものであり、吸収体を含む吸収性物品に好適に用いられる。
本発明の吸水性樹脂粒子が使用された吸水体は、吸収量に優れ、液の取り込み速度に優れるとともに、吸収後の加圧下のドライタッチ性に優れ、吸収体のひび割れや変形を抑制することができる。
The water-absorbent resin particles of the present invention constitute an absorbent body used for sanitary materials such as disposable diapers, sanitary napkins, incontinence pads, medical pads, etc., and are preferably used for absorbent articles containing the absorbent body. Be done.
The water absorber using the water-absorbent resin particles of the present invention has an excellent absorption amount, an excellent liquid uptake speed, and an excellent dry touch property under pressure after absorption, and suppresses cracking and deformation of the absorber. Can be done.
本発明の吸水性樹脂粒子を用いた吸収体は、例えば、吸水性樹脂粒子と親水性繊維より構成される。親水性繊維の具体例としては、木材からのメカニカルパルプ、ケミカルパルプ、セミケミカルパルプ、溶解パルプ等の木材パルプ繊維、レーヨン、アセテート等の人工セルロース繊維等を例示できる。好ましい親水性繊維は木材パルプ繊維である。これら親水性繊維はナイロン、ポリエステル等の合成繊維を一部含有していてもよい。 The absorber using the water-absorbent resin particles of the present invention is composed of, for example, water-absorbent resin particles and hydrophilic fibers. Specific examples of the hydrophilic fiber include mechanical pulp from wood, chemical pulp, semi-chemical pulp, wood pulp fiber such as dissolved pulp, artificial cellulose fiber such as rayon and acetate, and the like. The preferred hydrophilic fiber is wood pulp fiber. These hydrophilic fibers may partially contain synthetic fibers such as nylon and polyester.
吸収体における吸水性樹脂粒子の含有量としては、軽量かつ薄膜化の観点から、５〜９５質量％であることが好ましく、２０〜９０質量％であることがより好ましく、３０〜８０質量％であることがさらに好ましい。 The content of the water-absorbent resin particles in the absorber is preferably 5 to 95% by mass, more preferably 20 to 90% by mass, and 30 to 80% by mass from the viewpoint of light weight and thinning. It is more preferable to have.
吸収体の構成としては、吸水性樹脂粒子と親水性繊維とを均一な組成となるように混合することによって得られた混合分散体、層状の親水性繊維の間に吸水性樹脂粒子が挟まれたサンドイッチ構造体、吸水性樹脂粒子と親水性繊維とをティッシュで包んだ構造体等が挙げられる。なお、吸収体には、他の成分、例えば、吸収体の形態保持性を高めるための熱融着性合成繊維、ホットメルト接着剤、接着性エマルジョン等の接着性バインダーが配合されていてもよい。 As the composition of the absorber, the water-absorbent resin particles are sandwiched between the mixed dispersion obtained by mixing the water-absorbent resin particles and the hydrophilic fibers so as to have a uniform composition, and the layered hydrophilic fibers. Examples thereof include a sandwich structure, a structure in which water-absorbent resin particles and hydrophilic fibers are wrapped with a tissue, and the like. The absorber may contain other components, for example, an adhesive binder such as a heat-sealing synthetic fiber, a hot melt adhesive, or an adhesive emulsion for enhancing the shape retention of the absorber. ..
また、吸水性樹脂粒子を用いた吸収体を、液体が通過し得る液体透過性シート（トップシート）と、液体が通過し得ない液体不透過性シート（バックシート）との間に保持することによって、吸収性物品とすることができる。液体透過性シートは、身体と接触する側に配され、液体不透過性シートは、身体と接する反対側に配される。 Further, the absorber using the water-absorbent resin particles is held between the liquid permeable sheet (top sheet) through which the liquid can pass and the liquid permeable sheet (back sheet) through which the liquid cannot pass. Can be an absorbent article. The liquid permeable sheet is placed on the side that comes into contact with the body, and the liquid permeable sheet is placed on the opposite side that comes into contact with the body.
液体透過性シートとしては、ポリエチレン、ポリプロピレン、ポリエステル等の繊維からなる、エアスルー型、スパンボンド型、ケミカルボンド型、ニードルパンチ型等の不織布及び多孔質の合成樹脂シート等が挙げられる。また、液体不透過性シートとしては、ポリエチレン、ポリプロピレン、ポリ塩化ビニル等の樹脂からなる合成樹脂フィルム等が挙げられる。 Examples of the liquid permeable sheet include non-woven fabrics such as air-through type, spunbond type, chemical bond type and needle punch type, which are made of fibers such as polyethylene, polypropylene and polyester, and porous synthetic resin sheets. Examples of the liquid impermeable sheet include a synthetic resin film made of a resin such as polyethylene, polypropylene, and polyvinyl chloride.
以下、実施例及び比較例により本発明を更に説明するが、本発明はこれらに限定されるものではない。以下、特に定めない限り、部は重量部、％は重量％を示す。なお、吸水性樹脂の生理食塩水に対する保水量、荷重下吸収量、見掛け密度、ゲル強度及び吸収体の形状保持性は以下の方法により測定した。 Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified, parts are parts by weight and% are parts by weight. The amount of water retained by the water-absorbent resin in physiological saline, the amount absorbed under load, the apparent density, the gel strength, and the shape retention of the absorber were measured by the following methods.
＜保水量の測定方法＞
目開き６３μｍ（ＪＩＳ Ｚ８８０１−１：２００６）のナイロン網で作製したティーバッグ（縦２０ｃｍ、横１０ｃｍ）に測定試料１．００ｇを入れ、生理食塩水（食塩濃度０．９％）１，０００ｍｌ中に無撹拌下、１時間浸漬した後引き上げて、１５分間吊るして水切りした。その後、ティーバッグごと、遠心分離器にいれ、１５０Ｇで９０秒間遠心脱水して余剰の生理食塩水を取り除き、ティーバッグを含めた重量（ｈ１）を測定し、次式から保水量を求めた。なお、使用した生理食塩水及び測定雰囲気の温度は２５℃±２℃であった。（ｈ２）は、測定試料の無い場合について上記と同様の操作により計測したティーバッグの重量である。
保水量（ｇ／ｇ）＝（ｈ１）−（ｈ２）
<Measurement method of water retention>
Put 1.00 g of the measurement sample in a tea bag (length 20 cm, width 10 cm) made of a nylon net with an opening of 63 μm (JIS Z8801-1: 2006), and put it in 1,000 ml of physiological saline (salt concentration 0.9%). After soaking for 1 hour without stirring, the sample was pulled up and hung for 15 minutes to drain water. Then, the tea bags were placed in a centrifuge and centrifuged at 150 G for 90 seconds to remove excess physiological saline, the weight (h1) including the tea bags was measured, and the amount of water retained was calculated from the following formula. The temperature of the physiological saline used and the measurement atmosphere was 25 ° C. ± 2 ° C. (H2) is the weight of the tea bag measured by the same operation as above when there is no measurement sample.
Water retention (g / g) = (h1)-(h2)
＜荷重下吸収量の測定方法＞
目開き６３μｍ（ＪＩＳ Ｚ８８０１−１：２００６）のナイロン網を底面に貼った円筒型プラスチックチューブ（内径：２５ｍｍ、高さ：３４ｍｍ）内に、３０メッシュふるいと６０メッシュふるいを用いて２５０〜５００μｍの範囲にふるい分けした測定試料０．１６ｇを秤量し、円筒型プラスチックチューブを垂直にしてナイロン網上に測定試料がほぼ均一厚さになるように整えた後、この測定試料の上に分銅（重量：２００ｇ、外径：２４．５ｍｍ、）を乗せた。この円筒型プラスチックチューブ全体の重量（Ｍ１）を計量した後、生理食塩水（食塩濃度０．９％）６０ｍｌの入ったシャーレ（直径：１２ｃｍ）の中に測定試料及び分銅の入った円筒型プラスチックチューブを垂直に立ててナイロン網側を下面にして浸し、６０分静置した。６０分後に、円筒型プラスチックチューブをシャーレから引き上げ、これを斜めに傾けて底部に付着した水を一箇所に集めて水滴として垂らすことで余分な水を除去した後、測定試料及び分銅の入った円筒型プラスチックチューブ全体の重量（Ｍ２）を計量し、次式から加圧下吸収量を求めた。なお、使用した生理食塩水及び測定雰囲気の温度は２５℃±２℃であった。
荷重下吸収量（ｇ／ｇ）＝｛（Ｍ２）−（Ｍ１）｝／０．１６
<Measurement method of absorption under load>
250-500 μm using a 30-mesh sieve and a 60-mesh sieve in a cylindrical plastic tube (inner diameter: 25 mm, height: 34 mm) with a nylon mesh with a mesh opening of 63 μm (JIS Z8801-1: 2006) attached to the bottom surface. Weigh 0.16 g of the measurement sample sifted into the range, arrange the cylindrical plastic tube vertically on the nylon mesh so that the measurement sample has almost uniform thickness, and then put the weight (weight:) on this measurement sample. 200 g, outer diameter: 24.5 mm,) was placed. After weighing the entire weight (M1) of this cylindrical plastic tube, a cylindrical plastic containing a measurement sample and a weight is placed in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (salt concentration 0.9%). The tube was erected vertically and immersed with the nylon mesh side facing down, and allowed to stand for 60 minutes. After 60 minutes, the cylindrical plastic tube was pulled up from the petri dish, tilted diagonally, and the water adhering to the bottom was collected in one place and dropped as water droplets to remove excess water, and then the measurement sample and weight were contained. The weight (M2) of the entire cylindrical plastic tube was weighed, and the amount of absorption under pressure was calculated from the following equation. The temperature of the physiological saline used and the measurement atmosphere was 25 ° C. ± 2 ° C.
Absorption amount under load (g / g) = {(M2)-(M1)} /0.16
＜見掛け密度の測定方法＞
ＪＩＳ Ｋ ７３６５：１９９９に準拠して測定した。
<Measurement method of apparent density>
Measured according to JIS K 7365: 1999.
＜ゲル強度の測定方法＞ 人工尿［尿素２００重量部、塩化ナトリウム８０重量部、硫酸マグネシウム(７水塩)８重量部、塩化カルシウム(２水塩)３重量部、硫酸第２鉄（７水塩）２重量部、イオン交換水９７０４重量部］６０．０ｇを１００ｍｌビーカー（内径５ｃｍ）に量り取り、ＪＩＳ Ｋ７２２４−１９９６に記載された操作と同様にして、測定試料２．０ｇを精秤して上記ビーカーに投入し、３０倍膨潤ゲルを作成した。 この３０倍膨潤ゲルの入ったビーカーを４０±２℃の雰囲気下で３時間、さらに２５±２℃の雰囲気下で０．５時間静置した後、３０倍膨潤ゲルのゲル弾性率をカードメーター（たとえば、株式会社アイテックテクノエンジニアリング製をカードメーター・マックスＭＥ−５００）を用いて測定した。なお、カードメーターの条件は以下の通りである。・感圧軸：８ｍｍ・スプリング：１００ｇ用・荷重：１００ｇ・上昇速度：１インチ／７秒・試験性質：破断・測定時間：６秒・測定雰囲気温度：２５±２℃ <Measurement method of gel strength> Artificial urine [200 parts by weight of urea, 80 parts by weight of sodium chloride, 8 parts by weight of magnesium sulfate (7-hydrate), 3 parts by weight of calcium chloride (dihydrate), ferric sulfate (7 water) 2 parts by weight of salt), 9704 parts by weight of ion-exchanged water] Weigh 60.0 g in a 100 ml beaker (inner diameter 5 cm), and weigh 2.0 g of the measurement sample in the same manner as described in JIS K7224-1996. It was put into the above beaker to prepare a 30-fold swollen gel. After allowing the beaker containing the 30-fold swelling gel to stand in an atmosphere of 40 ± 2 ° C. for 3 hours and further in an atmosphere of 25 ± 2 ° C. for 0.5 hours, the gel elastic modulus of the 30-fold swelling gel is measured by a card meter. (For example, a product manufactured by Aitec Techno Engineering Co., Ltd. was measured using a card meter Max ME-500). The conditions of the card meter are as follows.・ Pressure sensitive shaft: 8mm ・ Spring: for 100g ・ Load: 100g ・ Rise speed: 1 inch / 7 seconds ・ Test properties: Breaking ・ Measurement time: 6 seconds ・ Measurement atmosphere temperature: 25 ± 2 ℃
＜吸収性物品の調製＞ フラッフパルプ１００部と評価試料｛吸水収性樹脂粒子｝１００部とを気流型混合装置｛株式会社オーテック社製パッドフォーマー｝で混合して、混合物を得た後、この混合物を坪量約５００ｇ／ｍ2となるように均一にアクリル板（厚み４ｍｍ）上に積層し、５Ｋｇ／ｃｍ2の圧力で３０秒間プレスし、吸収体を得た。この吸収体を１４ｃｍ×３６ｃｍの長方形に裁断し、各々の上下に吸収体と同じ大きさの吸水紙（坪量１５．５ｇ／ｍ2、アドバンテック社製、フィルターペーパー２番）を配置し、さらにポリエチレンシート（タマポリ社製ポリエチレンフィルムＵＢ−１）を裏面に、不織布（坪量２０ｇ／ｍ2、旭化成社製エルタスガード）を表面に配置することにより吸収性物品を調製した。 <Preparation of absorbent article> 100 parts of fluff pulp and 100 parts of evaluation sample {water-absorbing resin particles} are mixed with an air flow type mixer {Padformer manufactured by Otec Co., Ltd.} to obtain a mixture. This mixture was uniformly laminated on an acrylic plate (thickness 4 mm) so as to have a basis weight of about 500 g / m 2, and pressed at a pressure of 5 kg / cm 2 for 30 seconds to obtain an absorber. This absorber is cut into a rectangle of 14 cm x 36 cm, and water-absorbing paper (basis weight 15.5 g / m 2 , manufactured by Advantech, filter paper No. 2) of the same size as the absorber is placed above and below each. An absorbent article was prepared by arranging a polyethylene sheet (polyethylene film UB-1 manufactured by Tamapoli) on the back surface and a non-woven fabric (basis weight 20 g / m 2 , Ertus guard manufactured by Asahi Kasei Co., Ltd.) on the front surface.
＜形状保持性評価方法＞
得られた吸収性物品を３ｃｍ×８ｃｍの長方形に裁断し、生理食塩水を１２ｇ添加した。添加から１分後にチャック付きサンプル袋（株式会社生産日本社製、ユニパック Ｄ−４）に裁断した吸収性物品を入れて、内部を窒素ガスで満たし密栓した。吸収性物品を封入したサンプル袋を３０ｃｍ／秒の速度で上下に振幅３０ｃｍで３０回振り、試験後の吸収体内部の吸水性樹脂粒子の親水性繊維からの脱落の程度を４段階で評価した。
◎：吸水性樹脂粒子の脱落なし
○：吸水性樹脂粒子の一部（１／５未満）が脱落
△：吸収性樹脂粒子の１／５以上が脱落
×：裁断した吸収性物品が崩壊
<Shape retention evaluation method>
The obtained absorbent article was cut into a rectangle of 3 cm × 8 cm, and 12 g of physiological saline was added. One minute after the addition, the cut absorbent article was placed in a sample bag with a zipper (Unipack D-4 manufactured by Japan Co., Ltd.), and the inside was filled with nitrogen gas and sealed. The sample bag containing the absorbent article was shaken up and down at a speed of 30 cm / sec with an amplitude of 30 cm 30 times, and the degree of the water-absorbent resin particles inside the absorber falling off from the hydrophilic fibers after the test was evaluated on a 4-point scale. ..
⊚: No shedding of water-absorbent resin particles ○: Part of water-absorbent resin particles (less than 1/5) fall off Δ: 1/5 or more of absorbent resin particles fall off ×: Cut absorbent article collapses
＜製造例１＞
アクリル酸（ａ１−１）｛三菱化学株式会社製、純度１００％｝２７０部、架橋剤（ｂ−１）｛ペンタエリスリトールトリアリルエーテル、ダイソ−株式会社製｝０．９８部及びイオン交換水７１２部を攪拌・混合しながら３℃に保った。この混合物中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液１．１部、２％アスコルビン酸水溶液２．０部及び２％の２，２’−アゾビスアミジノプロパンジハイドロクロライド水溶液１３．５部を添加・混合して重合を開始させた。混合物の温度が８０℃に達した後、８０±２℃で約５時間熟成することにより含水ゲルを得た。
<Manufacturing example 1>
270 parts of acrylic acid (a1-1) {manufactured by Mitsubishi Chemical Co., Ltd., purity 100%}, 0.98 parts of cross-linking agent (b-1) {pentaerythritol triaryl ether, manufactured by Daiso Co., Ltd.} and ion-exchanged water 712 The part was kept at 3 ° C. while stirring and mixing. After influxing nitrogen into this mixture to reduce the amount of dissolved oxygen to 1 ppm or less, 1.1 parts of 1% hydrogen peroxide aqueous solution and 2.0 parts of 2% ascorbic acid aqueous solution and 2% 2,2'-azobis 13.5 parts of an aqueous solution of amidinopropane dihydrochloride was added and mixed to initiate polymerization. After the temperature of the mixture reached 80 ° C., it was aged at 80 ± 2 ° C. for about 5 hours to obtain a hydrogel.
次にこの含水ゲルをミンチ機（ＲＯＹＡＬ社製１２ＶＲ−４００Ｋ）で細断しながら、４９％水酸化ナトリウム水溶液２２０部を添加して混合・中和し、中和ゲルを得た。更に中和した含水ゲルを通気型乾燥機（井上金属製）を用い、供給温度１５０℃、風速１．５ｍ／秒の条件下で含水率が４％となるまで通気乾燥し、乾燥体を得た。乾燥体をジューサーミキサー（Ｏｓｔｅｒ社製ＯＳＴＥＲＩＺＥＲ ＢＬＥＮＤＥＲ）にて粉砕した後、ふるい分けして、目開き７１０〜１５０μｍの粒子径範囲に調整して、架橋重合体を含む樹脂粒子（Ａ−１）を得た。 Next, while shredding this hydrogel with a mincing machine (12VR-400K manufactured by ROYAL), 220 parts of a 49% sodium hydroxide aqueous solution was added and mixed / neutralized to obtain a neutralized gel. Further, the neutralized hydrogel was aerated and dried using an aeration type dryer (made by Inoue Metal) under the conditions of a supply temperature of 150 ° C. and a wind speed of 1.5 m / sec until the moisture content became 4% to obtain a dried product. It was. The dried product is pulverized with a juicer mixer (OSTERIZER BLENDER manufactured by Oster), sieved, and adjusted to a particle size range of 710 to 150 μm with a mesh size to obtain resin particles (A-1) containing a crosslinked polymer. It was.
ついで、得られた樹脂粒子（Ａ−１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに表面架橋剤（ｄ）としてのエチレングリコールジグリシジルエーテル０．１２部、プロピレングリコール１．０部、水不溶性無機微粒子（ｆ）としてのＫｌｅｂｏｓｏｌ３０ｃａｌ２５（ＡＺマテリアル社製コロイダルシリカ）１．０部及びイオン交換水１．７部を混合した混合液と、通液性向上剤としての硫酸ナトリウムアルミニウム１２水和物０．６部、プロピレングリコール０．６部及びイオン交換水１．５部を混合した混合液を同時に添加し、均一混合した後、１３５℃で３０分加熱して、表面架橋された樹脂粒子（Ａ−２）を得た。 Then, while stirring 100 parts of the obtained resin particles (A-1) at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), ethylene glycol diglycidyl ether 0 as a surface cross-linking agent (d) was added to the obtained resin particles (A-1). .12 parts, 1.0 part of propylene glycol, 1.0 part of Klebosol 30cal25 (colloidal silica manufactured by AZ Material Co., Ltd.) as water-insoluble inorganic fine particles (f), and 1.7 parts of ion-exchanged water are mixed and passed through the mixture. A mixture of 0.6 parts of sodium aluminum sulfate dodecahydrate, 0.6 parts of propylene glycol and 1.5 parts of ion-exchanged water as a property improver was added at the same time, and after uniform mixing, 30 at 135 ° C. The mixture was heated for a minute to obtain surface-crosslinked resin particles (A-2).
＜製造例２＞
得られた樹脂粒子（Ａ−１）１００部に使用する表面架橋剤（ｄ）をエチレングリコールジグリシジルエーテル０．１６部に、プロピレングリコール１．４部に、それぞれ変更したこと以外は製造例１と同様の表面架橋された樹脂粒子（Ａ−３）を得た。
<Manufacturing example 2>
Production Example 1 except that the surface cross-linking agent (d) used for 100 parts of the obtained resin particles (A-1) was changed to 0.16 parts of ethylene glycol diglycidyl ether and 1.4 parts of propylene glycol. The same surface-crosslinked resin particles (A-3) as in the above were obtained.
＜製造例３＞
得られた樹脂粒子（Ａ−１）１００部に使用する表面架橋剤（ｄ）をエチレングリコールジグリシジルエーテル０．０１部に、プロピレングリコール０．５部に、それぞれ変更したこと以外は製造例１と同様の表面架橋された樹脂粒子（Ａ−４）を得た。
<Manufacturing example 3>
Production Example 1 except that the surface cross-linking agent (d) used for 100 parts of the obtained resin particles (A-1) was changed to 0.01 part of ethylene glycol diglycidyl ether and 0.5 part of propylene glycol. The same surface-crosslinked resin particles (A-4) as in the above were obtained.
＜実施例１＞
製造例１で得られた樹脂粒子（Ａ−２）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、多価金属塩（Ｂ）としてポリ硫酸第二鉄水溶液（南海化学株式会社製、全鉄１１重量％）５．０部を添加し、均一に混合した。その後８０℃で３０分間加熱して、本発明の吸水性樹脂粒子（Ｐ−１）を得た。
<Example 1>
While stirring 100 parts of the resin particles (A-2) obtained in Production Example 1 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), an aqueous solution of ferric polysulfate as a polyvalent metal salt (B). 5.0 parts (manufactured by Nankai Chemical Co., Ltd., 11% by weight of total iron) was added and mixed uniformly. Then, it was heated at 80 ° C. for 30 minutes to obtain the water-absorbent resin particles (P-1) of the present invention.
＜実施例２＞
製造例１で得られた樹脂粒子（Ａ−２）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、多価金属塩（Ｂ）としてポリ塩化アルミニウム水溶液（南海化学株式会社製、酸化アルミニウム１０重量％）５．０部を添加し、均一に混合した。その後８０℃で３０分間加熱して、本発明の吸水性樹脂粒子（Ｐ−２）を得た。
<Example 2>
While stirring 100 parts of the resin particles (A-2) obtained in Production Example 1 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), a polyaluminum chloride aqueous solution (Nankai) was used as a polyvalent metal salt (B). 5.0 parts (10% by weight of aluminum oxide) manufactured by Chemical Co., Ltd. was added and mixed uniformly. Then, it was heated at 80 ° C. for 30 minutes to obtain the water-absorbent resin particles (P-2) of the present invention.
＜実施例３＞
実施例２において、樹脂粒子（Ａ−２）を樹脂粒子（Ａ−３）に変更する以外は、実施例２と同様の操作を行い、本発明の吸水性樹脂粒子（Ｐ−３）を得た。
<Example 3>
In Example 2, the same operation as in Example 2 was performed except that the resin particles (A-2) were changed to the resin particles (A-3) to obtain the water-absorbent resin particles (P-3) of the present invention. It was.
＜実施例４＞
実施例２において、樹脂粒子（Ａ−２）を樹脂粒子（Ａ−４）に変更する以外は、実施例２と同様の操作を行い、本発明の吸水性樹脂粒子（Ｐ−４）を得た。
<Example 4>
In Example 2, the same operation as in Example 2 was performed except that the resin particles (A-2) were changed to the resin particles (A-4) to obtain the water-absorbent resin particles (P-4) of the present invention. It was.
＜参考例５＞
実施例１において、樹脂粒子（Ａ−２）を樹脂粒子（Ａ−１）に変更する以外は、実施例１と同様の操作を行い、吸水性樹脂粒子（Ｐ−５）を得た。
< Reference example 5>
In Example 1, the same operation as in Example 1 was performed except that the resin particles (A-2) were changed to the resin particles (A-1) to obtain water-absorbent resin particles (P-5).
＜比較例１＞
製造例１で得られた樹脂粒子（Ａ−２）をそのまま比較用の吸水性樹脂粒子（Ｒ−１）とした。
<Comparative example 1>
The resin particles (A-2) obtained in Production Example 1 were used as they were as water-absorbent resin particles (R-1) for comparison.
＜比較例２＞
製造例１で得られた樹脂粒子（Ａ−２）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、ポリ塩化アルミニウム水溶液（南海化学株式会社製）３０．０部を添加し、均一に混合した。その後８０℃で３０分間加熱して、比較用の吸水性樹脂粒子（Ｒ−２）を得た。
<Comparative example 2>
While stirring 100 parts of the resin particles (A-2) obtained in Production Example 1 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), an aqueous solution of polyaluminum chloride (manufactured by Nankai Chemical Co., Ltd.) 30.0 Parts were added and mixed uniformly. Then, it was heated at 80 ° C. for 30 minutes to obtain water-absorbent resin particles (R-2) for comparison.
＜比較例３＞
製造例１で得られた樹脂粒子（Ａ−２）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、硫酸ナトリウムアルミニウム１２水和物５．０部、及びイオン交換水３．０部を混合した混合液を、均一に混合した。その後８０℃で３０分間加熱して、比較用の吸水性樹脂粒子（Ｒ−３）を得た。
<Comparative example 3>
While stirring 100 parts of the resin particles (A-2) obtained in Production Example 1 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), 5.0 parts of sodium aluminum sulfate dodecahydrate and ions. The mixed solution in which 3.0 parts of the exchanged water was mixed was uniformly mixed. Then, it was heated at 80 ° C. for 30 minutes to obtain water-absorbent resin particles (R-3) for comparison.
＜比較例４＞
比較例２において、ポリ塩化アルミニウム水溶液（南海化学株式会社製）１５．０部を０．４部に変更する以外は、比較例２と同様の操作を行い、比較用の吸水性樹脂粒子（Ｒ−４）を得た。
<Comparative example 4>
In Comparative Example 2, the same operation as in Comparative Example 2 was performed except that 15.0 parts of the polyaluminum chloride aqueous solution (manufactured by Nankai Chemical Co., Ltd.) was changed to 0.4 parts, and the water-absorbent resin particles (R) for comparison were performed. -4) was obtained.
実施例１〜４、参考例５の吸水性樹脂粒子（Ｐ−１）〜（Ｐ−５）及び比較例１〜４の吸水性樹脂粒子（Ｒ−１）〜（Ｒ−４）についての性能評価結果（保水量、荷重下吸収量、見掛け密度、ゲル強度）をした。結果を表１に示す。
Performance of the water-absorbent resin particles (P-1) to (P-5) of Examples 1 to 4 and Reference Example 5 and the water-absorbent resin particles (R-1) to (R-4) of Comparative Examples 1 to 4. The evaluation results (water retention amount, absorption amount under load, apparent density, gel strength) were obtained. The results are shown in Table 1.
＜吸収体の調製＞
フラッフパルプ１００部と実施例１で得られた吸水性樹脂粒子（Ｐ−１）１００部とを気流型混合装置｛株式会社オーテック社製パッドフォーマー｝で混合して、混合物を得た後、この混合物を坪量約５００ｇ／ｍ2となるように均一にアクリル板（厚み４ｍｍ）上に積層し、５Ｋｇ／ｃｍ2の圧力で３０秒間プレスし、吸収体を得た。この吸収体を１４ｃｍ×３６ｃｍの長方形に裁断し、各々の上下に吸収体と同じ大きさの吸水紙（坪量１５．５ｇ／ｍ2、アドバンテック社製、フィルターペーパー２番）を配置し、さらにポリエチレンシート（タマポリ社製ポリエチレンフィルムＵＢ−１）を裏面に、不織布（坪量２０ｇ／ｍ2、旭化成社製エルタスガード）を表面に配置することにより吸収性物品を調製した。
<Preparation of absorber>
After 100 parts of the fluff pulp and 100 parts of the water-absorbent resin particles (P-1) obtained in Example 1 were mixed with an air flow type mixer {Padformer manufactured by Otec Co., Ltd.} to obtain a mixture, This mixture was uniformly laminated on an acrylic plate (thickness 4 mm) so as to have a basis weight of about 500 g / m 2, and pressed at a pressure of 5 kg / cm 2 for 30 seconds to obtain an absorber. This absorber is cut into a rectangle of 14 cm x 36 cm, and water-absorbing paper (basis weight 15.5 g / m 2 , manufactured by Advantech, filter paper No. 2) of the same size as the absorber is placed above and below each. An absorbent article was prepared by arranging a polyethylene sheet (polyethylene film UB-1 manufactured by Tamapoli) on the back surface and a non-woven fabric (basis weight 20 g / m 2 , Ertus guard manufactured by Asahi Kasei Co., Ltd.) on the front surface.
吸水性樹脂粒子（Ｐ−１）を実施例２〜４、参考例５の吸水性樹脂粒子（Ｐ−２）〜（Ｐ−５）及び比較例１〜４の吸水性樹脂粒子（Ｒ−１）〜（Ｒ−４）に変更する以外は、上述と同様にしてそれぞれ吸収体および吸収性物品を調整した。得られた吸収性物品についての形状保持性評価結果を表１に示す。
The water-absorbent resin particles (P-1) are used in Examples 2 to 4, the water-absorbent resin particles (P-2) to (P-5) in Reference Example 5, and the water-absorbent resin particles (R-1) in Comparative Examples 1 to 4. )-(R-4), the absorber and the absorbent article were prepared in the same manner as described above, respectively. Table 1 shows the shape retention evaluation results of the obtained absorbent article.
実施例１と比較例１との比較から、多価金属塩（Ｂ）を含有することで吸収体の形状保持性が向上している。比較例２及び４から、多価金属塩（Ｂ）の含有量が適切でなければ、保水量や荷重下吸水量の吸水性能が劣ることがわかる。また、多価金属原子を２個しか含まない多価金属塩を使用した比較例３では、吸収体の形状保持性が劣ることがわかる。
本発明に記載の吸収性樹脂粒子は、多価金属塩（Ｂ）が粒子表面に偏在しており、ゲルの膨潤を阻害することがない為、本発明の吸収性樹脂粒子を用いた吸収性物品は吸収性能が良好になるとともに、吸収体のひび割れや変形を抑止する形状保持性に優れていることがわかる。
From the comparison between Example 1 and Comparative Example 1, the shape retention of the absorber is improved by containing the polyvalent metal salt (B). From Comparative Examples 2 and 4, it can be seen that if the content of the polyvalent metal salt (B) is not appropriate, the water absorption performance of the water retention amount and the water absorption amount under load is inferior. Further, in Comparative Example 3 using the multivalent metal salt containing only two polyvalent metal atoms, it can be seen that the shape retention of the absorber is inferior.
In the absorbent resin particles described in the present invention, the polyvalent metal salt (B) is unevenly distributed on the particle surface and does not inhibit the swelling of the gel. Therefore, the absorbent resin particles of the present invention are used for absorbability. It can be seen that the article has good absorption performance and is excellent in shape retention that suppresses cracking and deformation of the absorber.
Claims (8)
An absorbent article made by using the absorber according to claim 7 .
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