JP2006342306A - Method for producing porous water-absorbing polymer particle - Google Patents
Method for producing porous water-absorbing polymer particle Download PDFInfo
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- JP2006342306A JP2006342306A JP2005171420A JP2005171420A JP2006342306A JP 2006342306 A JP2006342306 A JP 2006342306A JP 2005171420 A JP2005171420 A JP 2005171420A JP 2005171420 A JP2005171420 A JP 2005171420A JP 2006342306 A JP2006342306 A JP 2006342306A
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- water
- absorbing polymer
- emulsion
- organic solvent
- aqueous solution
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- 239000002245 particle Substances 0.000 title claims abstract description 123
- 229920000642 polymer Polymers 0.000 title claims abstract description 98
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 24
- 239000000178 monomer Substances 0.000 claims abstract description 68
- 239000007864 aqueous solution Substances 0.000 claims abstract description 54
- 239000000839 emulsion Substances 0.000 claims abstract description 54
- 239000003960 organic solvent Substances 0.000 claims abstract description 36
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 31
- 239000004094 surface-active agent Substances 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims abstract description 23
- 229920002503 polyoxyethylene-polyoxypropylene Polymers 0.000 claims abstract description 13
- -1 polyoxyethylene Polymers 0.000 claims description 40
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 claims description 32
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 23
- 229920001400 block copolymer Polymers 0.000 claims description 15
- 235000014113 dietary fatty acids Nutrition 0.000 claims description 12
- 239000000194 fatty acid Substances 0.000 claims description 12
- 229930195729 fatty acid Natural products 0.000 claims description 12
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 10
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 claims description 6
- UAEPNZWRGJTJPN-UHFFFAOYSA-N methylcyclohexane Chemical compound CC1CCCCC1 UAEPNZWRGJTJPN-UHFFFAOYSA-N 0.000 claims description 6
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 claims description 6
- 239000003381 stabilizer Substances 0.000 claims description 6
- 239000002562 thickening agent Substances 0.000 claims description 6
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 5
- 239000004698 Polyethylene Substances 0.000 claims description 5
- 229930006000 Sucrose Natural products 0.000 claims description 5
- 239000004815 dispersion polymer Substances 0.000 claims description 5
- 229920000573 polyethylene Polymers 0.000 claims description 5
- 239000005720 sucrose Substances 0.000 claims description 5
- GYNNXHKOJHMOHS-UHFFFAOYSA-N methyl-cycloheptane Natural products CC1CCCCCC1 GYNNXHKOJHMOHS-UHFFFAOYSA-N 0.000 claims description 3
- FBPFZTCFMRRESA-FSIIMWSLSA-N D-Glucitol Natural products OC[C@H](O)[C@H](O)[C@@H](O)[C@H](O)CO FBPFZTCFMRRESA-FSIIMWSLSA-N 0.000 claims description 2
- 229920006242 ethylene acrylic acid copolymer Polymers 0.000 claims description 2
- 239000005038 ethylene vinyl acetate Substances 0.000 claims description 2
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 claims description 2
- 239000000600 sorbitol Substances 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 49
- 238000010521 absorption reaction Methods 0.000 abstract description 18
- 239000000243 solution Substances 0.000 abstract description 14
- 238000006116 polymerization reaction Methods 0.000 description 20
- 238000003756 stirring Methods 0.000 description 18
- 239000011148 porous material Substances 0.000 description 17
- 239000003431 cross linking reagent Substances 0.000 description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 238000000635 electron micrograph Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 229910052783 alkali metal Inorganic materials 0.000 description 10
- 230000001965 increasing effect Effects 0.000 description 10
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 8
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 7
- 229920000742 Cotton Polymers 0.000 description 7
- 150000001340 alkali metals Chemical class 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 7
- 238000004132 cross linking Methods 0.000 description 7
- 239000000499 gel Substances 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 6
- 229910001873 dinitrogen Inorganic materials 0.000 description 6
- 239000003505 polymerization initiator Substances 0.000 description 6
- 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 5
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 5
- 239000002253 acid Substances 0.000 description 5
- 230000018044 dehydration Effects 0.000 description 5
- 238000006297 dehydration reaction Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 4
- 206010021639 Incontinence Diseases 0.000 description 4
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical class CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 4
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 4
- 238000007664 blowing Methods 0.000 description 4
- 230000001186 cumulative effect Effects 0.000 description 4
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- 238000001035 drying Methods 0.000 description 4
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- 238000006386 neutralization reaction Methods 0.000 description 4
- 229910052700 potassium Inorganic materials 0.000 description 4
- 239000011591 potassium Substances 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 229910052708 sodium Inorganic materials 0.000 description 4
- 239000011734 sodium Substances 0.000 description 4
- 239000012798 spherical particle Substances 0.000 description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- 239000004354 Hydroxyethyl cellulose Substances 0.000 description 3
- 229920000663 Hydroxyethyl cellulose Polymers 0.000 description 3
- RVGRUAULSDPKGF-UHFFFAOYSA-N Poloxamer Chemical compound C1CO1.CC1CO1 RVGRUAULSDPKGF-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 235000011187 glycerol Nutrition 0.000 description 3
- 235000019447 hydroxyethyl cellulose Nutrition 0.000 description 3
- 229920001223 polyethylene glycol Polymers 0.000 description 3
- 230000000379 polymerizing effect Effects 0.000 description 3
- 229920001451 polypropylene glycol Polymers 0.000 description 3
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 3
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 description 2
- SYEWHONLFGZGLK-UHFFFAOYSA-N 2-[1,3-bis(oxiran-2-ylmethoxy)propan-2-yloxymethyl]oxirane Chemical compound C1OC1COCC(OCC1OC1)COCC1CO1 SYEWHONLFGZGLK-UHFFFAOYSA-N 0.000 description 2
- HDPLHDGYGLENEI-UHFFFAOYSA-N 2-[1-(oxiran-2-ylmethoxy)propan-2-yloxymethyl]oxirane Chemical compound C1OC1COC(C)COCC1CO1 HDPLHDGYGLENEI-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- 238000000944 Soxhlet extraction Methods 0.000 description 2
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical compound CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 description 2
- 229920004896 Triton X-405 Polymers 0.000 description 2
- 239000002250 absorbent Substances 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 2
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000004945 emulsification Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 150000002170 ethers Chemical class 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 235000013305 food Nutrition 0.000 description 2
- 125000003055 glycidyl group Chemical group C(C1CO1)* 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052751 metal Chemical class 0.000 description 2
- 239000002184 metal Chemical class 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002504 physiological saline solution Substances 0.000 description 2
- 229920001983 poloxamer Polymers 0.000 description 2
- 229920005862 polyol Polymers 0.000 description 2
- 150000003077 polyols Chemical class 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 239000007870 radical polymerization initiator Substances 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- LUEWUZLMQUOBSB-FSKGGBMCSA-N (2s,3s,4s,5s,6r)-2-[(2r,3s,4r,5r,6s)-6-[(2r,3s,4r,5s,6s)-4,5-dihydroxy-2-(hydroxymethyl)-6-[(2r,4r,5s,6r)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxan-3-yl]oxy-4,5-dihydroxy-2-(hydroxymethyl)oxan-3-yl]oxy-6-(hydroxymethyl)oxane-3,4,5-triol Chemical compound O[C@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@H]1O[C@@H]1[C@@H](CO)O[C@@H](O[C@@H]2[C@H](O[C@@H](OC3[C@H](O[C@@H](O)[C@@H](O)[C@H]3O)CO)[C@@H](O)[C@H]2O)CO)[C@H](O)[C@H]1O LUEWUZLMQUOBSB-FSKGGBMCSA-N 0.000 description 1
- 125000000954 2-hydroxyethyl group Chemical group [H]C([*])([H])C([H])([H])O[H] 0.000 description 1
- AUZRCMMVHXRSGT-UHFFFAOYSA-N 2-methylpropane-1-sulfonic acid;prop-2-enamide Chemical class NC(=O)C=C.CC(C)CS(O)(=O)=O AUZRCMMVHXRSGT-UHFFFAOYSA-N 0.000 description 1
- BTYIFQSAIPDZQW-UHFFFAOYSA-N 2-propan-2-yl-4,5-dihydro-1h-imidazole Chemical compound CC(C)C1=NCCN1 BTYIFQSAIPDZQW-UHFFFAOYSA-N 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- 229920001353 Dextrin Polymers 0.000 description 1
- 239000004375 Dextrin Substances 0.000 description 1
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 229920002581 Glucomannan Polymers 0.000 description 1
- 229920002907 Guar gum Polymers 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- LXEKPEMOWBOYRF-UHFFFAOYSA-N [2-[(1-azaniumyl-1-imino-2-methylpropan-2-yl)diazenyl]-2-methylpropanimidoyl]azanium;dichloride Chemical compound Cl.Cl.NC(=N)C(C)(C)N=NC(C)(C)C(N)=N LXEKPEMOWBOYRF-UHFFFAOYSA-N 0.000 description 1
- MZVQCMJNVPIDEA-UHFFFAOYSA-N [CH2]CN(CC)CC Chemical group [CH2]CN(CC)CC MZVQCMJNVPIDEA-UHFFFAOYSA-N 0.000 description 1
- 150000003926 acrylamides Chemical class 0.000 description 1
- 150000004996 alkyl benzenes Chemical class 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 239000003945 anionic surfactant Substances 0.000 description 1
- 238000010533 azeotropic distillation Methods 0.000 description 1
- 239000007869 azo polymerization initiator Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 229940105329 carboxymethylcellulose Drugs 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 229920001940 conductive polymer Polymers 0.000 description 1
- 235000019425 dextrin Nutrition 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 230000001804 emulsifying effect Effects 0.000 description 1
- GKIPXFAANLTWBM-UHFFFAOYSA-N epibromohydrin Chemical compound BrCC1CO1 GKIPXFAANLTWBM-UHFFFAOYSA-N 0.000 description 1
- VIBDJEWPNNCFQO-UHFFFAOYSA-N ethane-1,1,2-triol Chemical compound OCC(O)O VIBDJEWPNNCFQO-UHFFFAOYSA-N 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000004088 foaming agent Substances 0.000 description 1
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000007863 gel particle Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229940046240 glucomannan Drugs 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000000665 guar gum Substances 0.000 description 1
- 235000010417 guar gum Nutrition 0.000 description 1
- 229960002154 guar gum Drugs 0.000 description 1
- 239000000017 hydrogel Substances 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 229940071826 hydroxyethyl cellulose Drugs 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- NQXWGWZJXJUMQB-UHFFFAOYSA-K iron trichloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].Cl[Fe+]Cl NQXWGWZJXJUMQB-UHFFFAOYSA-K 0.000 description 1
- LAPRIVJANDLWOK-UHFFFAOYSA-N laureth-5 Polymers CCCCCCCCCCCCOCCOCCOCCOCCOCCO LAPRIVJANDLWOK-UHFFFAOYSA-N 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 125000005641 methacryl group Chemical group 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
- 239000002736 nonionic surfactant Substances 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
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- 239000000843 powder Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
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- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 1
- 241000894007 species Species 0.000 description 1
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- 235000020679 tap water Nutrition 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Landscapes
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Polymerisation Methods In General (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
Description
本発明は、多孔質吸水性ポリマー粒子の製造法に関する。さらに詳しくは、Ｏ／Ｗ／Ｏエマルジョン［油中水中油型エマルジョン]を用いて、樹脂内部に多数の空孔を有する多孔質吸水性ポリマー粒子を製造する方法に関する。多孔質吸水性ポリマー粒子は、紙オムツ、生理用ナプキン、失禁パッド、ペットシートなどに有用である。 The present invention relates to a method for producing porous water-absorbing polymer particles. More specifically, the present invention relates to a method for producing porous water-absorbing polymer particles having a large number of pores inside a resin using an O / W / O emulsion [oil-in-oil emulsion]. The porous water-absorbing polymer particles are useful for paper diapers, sanitary napkins, incontinence pads, pet sheets and the like.
一般に、吸水性ポリマーを製造する方法として、逆相懸濁重合法や水溶液重合法により、アクリル酸やそのアルカリ金属中和塩などの水溶性エチレン性不飽和単量体を重合させて吸水性ポリマーを製造する方法がよく知れられている。これらの製造法によって得られた吸水性ポリマーは、主に紙オムツや生理用ナプキンなどの衛材用途に広く利用されている。これらの衛材用途のなかでも特に、ナプキン、失禁パッド、ペットシートなどには、その使用目的を考慮して、より速い体液吸収速度が望まれており、その実現のために、より速い吸水速度をもつ吸水性ポリマーの開発が望まれている。 In general, as a method for producing a water-absorbing polymer, a water-absorbing polymer is obtained by polymerizing water-soluble ethylenically unsaturated monomers such as acrylic acid and alkali metal neutralized salts thereof by a reverse phase suspension polymerization method or an aqueous solution polymerization method. The method of manufacturing is well known. Water-absorbing polymers obtained by these production methods are widely used mainly for sanitary materials such as paper diapers and sanitary napkins. Among these hygiene materials, in particular, napkins, incontinence pads, pet sheets, etc. are expected to have a faster fluid absorption rate in consideration of their intended use. The development of a water-absorbing polymer having a high molecular weight is desired.
吸水速度が改善された吸水性ポリマーの製造法として、重合の際に炭酸塩発泡剤を用いて吸水性ポリマー内に気泡を生じさせる方法（例えば、特許文献１参照）、Ｏ／Ｗ／Ｏエマルジョンを用いてモノマーを重合させて粒子内部に空孔を形成させることにより、その吸水速度を向上させる方法（例えば、特許文献２および特許文献３参照）などが知られている。 As a method for producing a water-absorbing polymer with improved water absorption rate, a method of generating bubbles in the water-absorbing polymer using a carbonate foaming agent during polymerization (for example, see Patent Document 1), an O / W / O emulsion A method for improving the water absorption rate by polymerizing a monomer to form pores inside the particles using, for example (see Patent Document 2 and Patent Document 3) is known.
しかし、これらの方法で得られる吸水性ポリマーの内部の空孔は、そのほとんどが粒子内部の独立空孔であることから、実質的なポリマー粒子の表面積があまり増大していないためか、吸水速度の向上が充分であるとはいえない。また、これらの方法において、多孔性を向上させるために、モノマーに内包される有機溶媒量を増加させると、Ｏ／Ｗ／Ｏエマルジョンが不安定となり、結果的に内部に空孔を有する粒子が得られない傾向となる。 However, most of the pores inside the water-absorbing polymer obtained by these methods are independent pores inside the particles, so the surface area of the polymer particles does not increase so much. The improvement is not sufficient. Further, in these methods, if the amount of the organic solvent included in the monomer is increased in order to improve the porosity, the O / W / O emulsion becomes unstable, and as a result, particles having pores therein are formed. It tends to be unobtainable.
一方、連続空孔をもつ樹脂の製造法の１つとして、高内部相エマルジョン（High Internal Phase Emulsion）と呼ばれる、Ｏ／Ｗ比（Ｗ／Ｏ比）が高いエマルジョンを製造する技術を利用して吸水性ポリマー粒子を製造する方法が知られている（例えば、特許文献４参照）。 On the other hand, as one of the methods for producing a resin having continuous pores, a technique called high internal phase emulsion (High Internal Phase Emulsion) is used to produce an emulsion having a high O / W ratio (W / O ratio). A method for producing water-absorbing polymer particles is known (for example, see Patent Document 4).
しかし、この方法には、複数種の有機溶媒を使用する必要があり、また、低温で重合を行うことから、重合時間が長く、その結果、生産性が低いという欠点がある。また、この方法によって得られた粒子は嵩密度が０．０５〜０．２５（ｇ／ｍＬ）と小さい。このような嵩密度の小さい多孔質吸水性ポリマーは、内部の空孔が大きすぎるためか、機械的強度が不十分であるため、ナプキンなどの吸収体を製造する際に粒子が破砕してしまうことから、衛材用途には適していない。
本発明は、前記従来技術に鑑みてなされたものであり、多数の連続空孔および適度な嵩密度を有し、吸水速度に優れた多孔質吸水性ポリマー粒子を効率よく製造しうる方法を提供することを課題とする。 The present invention has been made in view of the above prior art, and provides a method for efficiently producing porous water-absorbing polymer particles having a large number of continuous pores and an appropriate bulk density and excellent in water absorption speed. The task is to do.
本発明は、水溶性エチレン性不飽和単量体水溶液を用いて吸水性ポリマー粒子を製造する方法であって、水溶性エチレン性不飽和単量体水溶液に、第１界面活性剤の存在下、第１疎水性有機溶媒を内包させ、Ｏ／Ｗエマルジョンを得る工程、及び得られたＯ／Ｗエマルジョンを、第２界面活性剤を含有する第２疎水性有機溶媒に分散させてＯ／Ｗ／Ｏエマルジョンを得る工程を有し、第１界面活性剤としてポリオキシエチレン−ポリオキシプロピレン共重合体を用いることを特徴とする、嵩密度が０．３０〜０．５０ｇ／ｍＬである多孔質吸水性ポリマー粒子の製造法に関する。 The present invention is a method for producing water-absorbing polymer particles using a water-soluble ethylenically unsaturated monomer aqueous solution, the water-soluble ethylenically unsaturated monomer aqueous solution in the presence of a first surfactant, A step of encapsulating a first hydrophobic organic solvent to obtain an O / W emulsion, and the obtained O / W emulsion is dispersed in a second hydrophobic organic solvent containing a second surfactant to obtain an O / W / Porous water absorption having a bulk density of 0.30 to 0.50 g / mL, characterized by comprising a step of obtaining an O emulsion and using a polyoxyethylene-polyoxypropylene copolymer as the first surfactant The present invention relates to a method for producing conductive polymer particles.
本発明の製造法によれば、多数の連続空孔および適度な嵩密度を有し、吸水速度に優れた多孔質吸水性ポリマー粒子を効率よく製造することができる。 According to the production method of the present invention, it is possible to efficiently produce porous water-absorbing polymer particles having a large number of continuous pores and an appropriate bulk density and having an excellent water absorption rate.
本発明の多孔質吸水性ポリマー粒子の製造法は、少なくとも次の２つの工程を有する。 The method for producing porous water-absorbing polymer particles of the present invention has at least the following two steps.
第１工程として、水溶性エチレン性不飽和単量体水溶液に、第１界面活性剤の存在下、第１疎水性有機溶媒を内包させて、Ｏ／Ｗエマルジョンを調製する。 As a first step, an O / W emulsion is prepared by encapsulating a first hydrophobic organic solvent in a water-soluble ethylenically unsaturated monomer aqueous solution in the presence of a first surfactant.
次に、第２工程として、得られたＯ／Ｗエマルジョンを第２界面活性剤を含有する第２疎水性有機溶媒に分散させて、Ｏ／Ｗ／Ｏエマルジョンを調製する。 Next, as a second step, the obtained O / W emulsion is dispersed in a second hydrophobic organic solvent containing a second surfactant to prepare an O / W / O emulsion.
本発明では、第１工程で第１界面活性剤として、ポリオキシエチレン−ポリオキシプロピレン共重合体が用いられている点に、大きな特徴がある。本発明では、このようにポリオキシエチレン−ポリオキシプロピレン共重合体が用いられているので、Ｏ／Ｗ／Ｏエマルジョンの重合時の安定性を向上させ、多数の連続空孔を形成させることができるという利点がある。 The present invention is greatly characterized in that a polyoxyethylene-polyoxypropylene copolymer is used as the first surfactant in the first step. In the present invention, since the polyoxyethylene-polyoxypropylene copolymer is used in this way, it is possible to improve the stability during polymerization of the O / W / O emulsion and to form a large number of continuous pores. There is an advantage that you can.
ポリオキシエチレン−ポリオキシプロピレン共重合体としては、ポリオキシエチレンとポリオキシプロピレンとが共重合したものであれば特に限定されないが、そのなかでも、一般式(I):
HO−(C２H４O)a−(C３Ｈ６O)ｂ−(C２H４O)c−H (I)
（式中、ａ、ｂおよびｃは、それぞれ重合度を示す）
で表されるポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体が好ましい。なお、式(I)中、ａ及びｃは、それぞれ、０以上の整数であり、かつ（ａ＋ｃ）が２５〜２０００の整数であり、ｂは５〜１０００の整数であることが好ましい。
The polyoxyethylene-polyoxypropylene copolymer is not particularly limited as long as it is a copolymer of polyoxyethylene and polyoxypropylene, but among them, the general formula (I):
HO- (C 2 H 4 O) a - (C 3 H 6 O) b - (C 2 H 4 O) c -H (I)
(Wherein a, b and c each represent the degree of polymerization)
The polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer represented by these is preferable. In formula (I), a and c are each an integer of 0 or more, (a + c) is preferably an integer of 25 to 2000, and b is preferably an integer of 5 to 1000.
ポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体の質量平均分子量は、Ｏ／Ｗ／Ｏエマルジョンの重合時の安定性を向上させ、多数の連続空孔を形成させる観点から、好ましくは３０００以上、より好ましくは５０００以上であり、水溶性を高め、作業性を向上させる観点から、好ましくは１０００００以下、より好ましくは３００００以下である。これらの観点から、ポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体の質量平均分子量は、好ましくは３０００〜１０００００、より好ましくは５０００〜３００００である。 The weight average molecular weight of the polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer is preferably from the viewpoint of improving the stability during polymerization of the O / W / O emulsion and forming a large number of continuous pores. It is 3000 or more, more preferably 5000 or more. From the viewpoint of improving water solubility and improving workability, it is preferably 100,000 or less, more preferably 30000 or less. From these viewpoints, the mass average molecular weight of the polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer is preferably 3000 to 100,000, more preferably 5000 to 30000.
ポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体におけるポリオキシエチレンの含有量は、Ｏ／Ｗ／Ｏエマルジョンの状態で水溶性エチレン性不飽和単量体が重合する際に好適な乳化状態を維持し、粒子内部に連続空孔を形成しやすくする観点から、好ましくは４０質量％以上、より好ましくは４５質量％以上であり、Ｏ／Ｗエマルジョンを安定化させる観点から、好ましくは９０質量％以下、より好ましくは８５質量％以下である。これらの観点から、ポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体におけるポリオキシエチレンの含有量は、好ましくは４０〜９０質量％、より好ましくは４５〜８５質量％である。 The polyoxyethylene content in the polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer is an emulsification suitable for the polymerization of a water-soluble ethylenically unsaturated monomer in the state of an O / W / O emulsion. From the viewpoint of maintaining the state and facilitating the formation of continuous pores inside the particles, it is preferably 40% by mass or more, more preferably 45% by mass or more, and from the viewpoint of stabilizing the O / W emulsion, preferably 90%. It is not more than mass%, more preferably not more than 85 mass%. From these viewpoints, the polyoxyethylene content in the polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer is preferably 40 to 90 mass%, more preferably 45 to 85 mass%.
ポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体は、工業的に容易に入手しうるものである。その代表例としては、旭電化工業（株）製、商品名「アデカプルロニック」シリーズ、バスフ（ＢＡＳＦ）社製、商品名「ＰＬＵＲＯＮＩＣ」シリーズ、三洋化成工業（株）製、商品名「ニューポール」シリーズなどが挙げられるが、本発明は、かかる例示のみに限定されるものではない。なお、これらのポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体は、それぞれ単独で用いてもよく、２種以上を併用してもよい。 The polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer is easily available industrially. Representative examples include Asahi Denka Kogyo Co., Ltd., trade name “Adeka Pluronic” series, Basf (BASF), trade name “PLURONIC” series, Sanyo Kasei Kogyo Co., Ltd., trade name “New Pole”. Although series etc. are mentioned, this invention is not limited only to this illustration. In addition, these polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymers may be used alone or in combination of two or more.
第１界面活性剤（ポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体）の量は、エチレン性不飽和単量体水溶液に疎水性有機溶媒を内包させやすくする観点から、エチレン性不飽和単量体水溶液１００重量部に対して、好ましくは０．１重量部以上、より好ましくは０．５重量部以上であり、過剰量を添加しても、見あうだけの効果が得られず、かえって経済的でなくなる傾向があることから、エチレン性不飽和単量体水溶液１００重量部に対して、好ましくは５重量部以下、より好ましくは２重量部以下である。これらの観点から、ポリオキシエチレン−ポリオキシプロピレン−ポリオキシエチレンブロック共重合体の量は、エチレン性不飽和単量体水溶液１００重量部に対して、好ましくは０．１〜５重量部、より好ましくは０．５〜２重量部である。 The amount of the first surfactant (polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer) is selected from the viewpoint of facilitating inclusion of the hydrophobic organic solvent in the ethylenically unsaturated monomer aqueous solution. The amount is preferably not less than 0.1 parts by weight, more preferably not less than 0.5 parts by weight, based on 100 parts by weight of the saturated monomer aqueous solution. However, since it tends to be less economical, the amount is preferably 5 parts by weight or less, more preferably 2 parts by weight or less with respect to 100 parts by weight of the ethylenically unsaturated monomer aqueous solution. From these viewpoints, the amount of the polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated monomer aqueous solution. Preferably it is 0.5-2 weight part.
水溶性エチレン性不飽和単量体としては、例えば、（メタ）アクリル酸およびその金属塩、無水マレイン酸、２−（メタ）アクリルアミド−２−メチルプロパンスルホン酸およびその金属塩；（メタ）アクリルアミド、Ｎ,Ｎ−ジメチル（メタ）アクリルアミド、２−ヒドロキシエチル（メタ）アクリレート、Ｎ−メチロール（メタ）アクリルアミドなどのノニオン性単量体；ジエチルアミノエチル（メタ）アクリレート、ジエチルアミノプロピル（メタ）アクリレートなどのアミノ基含有の不飽和単量体およびそれらの四級化物などが挙げられ、これらは、それぞれ単独で用いてもよく、２種以上を混合して用いてもよい。 Examples of the water-soluble ethylenically unsaturated monomer include (meth) acrylic acid and its metal salt, maleic anhydride, 2- (meth) acrylamide-2-methylpropanesulfonic acid and its metal salt; (meth) acrylamide Nonionic monomers such as N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide; diethylaminoethyl (meth) acrylate, diethylaminopropyl (meth) acrylate, etc. Examples thereof include amino group-containing unsaturated monomers and quaternized products thereof, and these may be used alone or in combination of two or more.
アルカリ金属塩におけるアルカリ金属としては、リチウム、ナトリウム、カリウムなどが挙げられ、これらのなかでは、得られる吸水性ポリマーが吸水量に優れ、かつ経済的であることから、ナトリウムおよびカリウムが好ましい。 Examples of the alkali metal in the alkali metal salt include lithium, sodium, potassium, and the like. Among these, sodium and potassium are preferable because the resulting water-absorbing polymer is excellent in water absorption and economical.
なお、本明細書において、「（メタ）アクリ」とは、「アクリ」および／または「メタクリ」を意味する。 In the present specification, “(meth) acryl” means “acryl” and / or “methacryl”.
好適な水溶性エチレン性不飽和単量体としては、工業的に入手が容易な点で、アクリル酸およびそのアルカリ金属塩、メタクリル酸およびそのアルカリ金属塩、アクリルアミドなどが挙げられる。 Suitable water-soluble ethylenically unsaturated monomers include acrylic acid and its alkali metal salts, methacrylic acid and its alkali metal salts, acrylamide and the like because they are easily available industrially.
水溶性エチレン性不飽和単量体は、通常、水溶液として用いられる。水溶性エチレン性不飽和単量体水溶液における単量体の濃度は、通常、好ましくは３０質量％〜飽和濃度、より好ましくは３５〜４５質量％である。水溶性エチレン性不飽和単量体水溶液に用いられる水は、特に限定されるものではなく、例えば、水道水、蒸留水、イオン交換水などが挙げられる。 The water-soluble ethylenically unsaturated monomer is usually used as an aqueous solution. The concentration of the monomer in the water-soluble ethylenically unsaturated monomer aqueous solution is usually preferably 30% by mass to saturated concentration, more preferably 35 to 45% by mass. The water used for the water-soluble ethylenically unsaturated monomer aqueous solution is not particularly limited, and examples thereof include tap water, distilled water, and ion exchange water.
水溶性エチレン性不飽和単量体水溶液に用いられる単量体が酸基を含む場合、その酸基を、アルカリ金属を含有する化合物などを用いて中和してもよい。この場合、酸基の中和度は、得られる吸水性ポリマーの浸透圧を高くし、吸水速度を高める一方で、安全性を考慮して余剰のアルカリ金属量を低減させる観点から、水溶性エチレン性不飽和単量体の酸基の好ましくは１０〜１００モル％、より好ましくは５０〜９０モル％、さらに好ましくは６０〜８０モル％である。前記アルカリ金属としては、リチウム、ナトリウム、カリウムなどが挙げられる。これらの中では、ナトリウムおよびカリウムが好ましい。 When the monomer used in the water-soluble ethylenically unsaturated monomer aqueous solution contains an acid group, the acid group may be neutralized using a compound containing an alkali metal. In this case, the neutralization degree of the acid group increases the osmotic pressure of the resulting water-absorbing polymer and increases the water absorption speed, while considering the safety and reducing the amount of excess alkali metal, water-soluble ethylene. Preferably it is 10-100 mol%, More preferably, it is 50-90 mol%, More preferably, it is 60-80 mol% of the acid group of a polymerizable unsaturated monomer. Examples of the alkali metal include lithium, sodium, and potassium. Of these, sodium and potassium are preferred.
酸基の中和は、例えば、水酸化ナトリウム、水酸化カリウムなどのアルカリ金属を含有する化合物の水溶液を水溶性エチレン性不飽和単量体またはその水溶液に滴下して混合することにより行うことができる。前記水溶液におけるアルカリ金属を含有する化合物の濃度は、特に限定されるものではないが、通常、２０〜５０質量％程度である。 The neutralization of the acid group can be performed, for example, by dropping an aqueous solution of a compound containing an alkali metal such as sodium hydroxide or potassium hydroxide into the water-soluble ethylenically unsaturated monomer or the aqueous solution thereof. it can. Although the density | concentration of the compound containing the alkali metal in the said aqueous solution is not specifically limited, Usually, it is about 20-50 mass%.
重合開始剤は、均一に分散させるために、あらかじめ水溶性エチレン性不飽和単量体水溶液に添加しておくことが好ましい。 The polymerization initiator is preferably added in advance to a water-soluble ethylenically unsaturated monomer aqueous solution in order to uniformly disperse the polymerization initiator.
重合開始剤として、水溶性ラジカル重合開始剤を用いることができる。水溶性ラジカル重合開始剤としては、例えば、過硫酸カリウム、過硫酸ナトリウム、過硫酸アンモニウムなどの過硫酸塩；２，２’−アゾビス（２−アミジノプロパン）２塩酸塩、２，２’−アゾビス（２−（２イミダゾリン−２−イル）プロパン）２塩酸塩などのアゾ系重合開始剤；過酸化水素などが挙げられるが、本発明は、かかる例示のみに限定されるものではない。これらの中では、工業的に入手が容易であるとともに保存安定性に優れていることから、過硫酸カリウムおよび過硫酸ナトリウムが好ましい。 A water-soluble radical polymerization initiator can be used as the polymerization initiator. Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis ( An azo polymerization initiator such as 2- (2imidazolin-2-yl) propane) dihydrochloride; hydrogen peroxide and the like may be mentioned, but the present invention is not limited to such examples. Among these, potassium persulfate and sodium persulfate are preferable because they are easily available industrially and are excellent in storage stability.
重合開始剤の使用量は、通常、水溶性エチレン性不飽和単量体1モルあたり０．０５〜１０ミリモルであることが好ましい。 Usually, the amount of the polymerization initiator used is preferably 0.05 to 10 mmol per 1 mol of the water-soluble ethylenically unsaturated monomer.
また、得られる多孔質吸水性ポリマー粒子のゲル強度を高める観点から、２個以上の重合性不飽和基や２個以上の反応基を有する架橋剤を、内部架橋剤として用いることが好ましい。内部架橋剤は、均一に分散させるために、あらかじめ水溶性エチレン性不飽和単量体水溶液に添加しておくことが好ましい。 Moreover, it is preferable to use a crosslinking agent having two or more polymerizable unsaturated groups or two or more reactive groups as an internal crosslinking agent from the viewpoint of increasing the gel strength of the resulting porous water-absorbing polymer particles. The internal cross-linking agent is preferably added in advance to a water-soluble ethylenically unsaturated monomer aqueous solution in order to uniformly disperse.
内部架橋剤の具体例としては、エチレングリコール、プロピレングリコール、トリメチロールプロパン、グリセリン、ポリオキシエチレングリコール、ポリオキシプロピレングリコール、ポリグリセリンなどのポリオール類のジまたはトリ（メタ）アクリル酸エステル類；Ｎ，Ｎ’−メチレンビスアクリルアミドなどのビス（メタ）アクリルアミド類；ポリエポキシドと（メタ）アクリル酸とを反応させて得られるジまたはトリ（メタ）アクリル酸エステル類；（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）プロピレングリコールジグリシジルエーテル、（ポリ）グリセリントリグリシジルエーテルなどの２個以上のグリシジル基をもつエーテル化合物；エピクロルヒドリン、エピブロムヒドリン、α−メチルエピクロルヒドリンなどのハロエポキシ化合物などの反応性官能基を２個以上有する化合物が挙げられ、これらは、それぞれ単独でまたは２種以上を混合して用いることができる。 Specific examples of the internal cross-linking agent include di- or tri (meth) acrylic acid esters of polyols such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; N Bis (meth) acrylamides such as N'-methylenebisacrylamide; di- or tri (meth) acrylic esters obtained by reacting polyepoxide with (meth) acrylic acid; (poly) ethylene glycol diglycidyl ether; Ether compounds having two or more glycidyl groups such as (poly) propylene glycol diglycidyl ether and (poly) glycerin triglycidyl ether; epichlorohydrin, epibromohydrin, α-methylepichlorohydride They include compounds having a reactive functional group such as haloepoxy compounds such as down two or more, they may be used alone or in admixture of two or more thereof.
内部架橋剤の使用量は、水溶性エチレン性不飽和単量体を重合して得られるポリマーが、適度な架橋により充分なゲル強度と保水能を示すようにする観点から、水溶性エチレン性不飽和単量体1モルあたり、好ましくは３０ミリモル以下、より好ましくは０．００１〜１０ミリモル、さらに好ましくは０．０１〜１ミリモルである。 The amount of the internal cross-linking agent used is such that the polymer obtained by polymerizing the water-soluble ethylenically unsaturated monomer exhibits a sufficient gel strength and water retention capability by appropriate cross-linking. The amount is preferably 30 mmol or less, more preferably 0.001 to 10 mmol, and still more preferably 0.01 to 1 mmol per 1 mol of the saturated monomer.
水溶性エチレン性不飽和単量体水溶液に内包させる第１疎水性有機溶媒としては、例えば、ｎ−ペンタン、ｎ−ヘキサン、ｎ−ヘプタン、ｎ−オクタン、シクロヘキサン、メチルシクロヘキサンなどの炭化水素系有機溶媒などが好ましい。これらのなかでは、工業的に入手が容易で品質が安定しており、比較的安価であることから、ｎ−ヘキサン、ｎ−ヘプタンおよびシクロヘキサンがより好ましい。 Examples of the first hydrophobic organic solvent encapsulated in the water-soluble ethylenically unsaturated monomer aqueous solution include hydrocarbon-based organic solvents such as n-pentane, n-hexane, n-heptane, n-octane, cyclohexane, and methylcyclohexane. A solvent or the like is preferable. Among these, n-hexane, n-heptane and cyclohexane are more preferable because they are easily available industrially, have stable quality, and are relatively inexpensive.
第１疎水性有機溶媒の使用量は、得られる多孔質吸水性ポリマー粒子の空孔の数や大きさなどに大きく関係している。第１疎水性有機溶媒と水溶性エチレン性不飽和単量体水溶液の体積比〔第１疎水性有機溶媒の体積（ｍＬ）／水溶性エチレン性不飽和単量体水溶液体積（ｍＬ）〕は、得られる多孔質吸水性ポリマー粒子が、粒子の表面から内部に至るまで連続空孔を形成することにより、吸水速度を高める観点から、好ましくは１．０以上、より好ましくは１．５以上であり、また、乳化を安定化させることにより、水溶性エチレン性不飽和単量体水溶液が第１疎水性有機溶媒を十分に内包できるようにする観点から、好ましくは３．０以下、より好ましくは２．５以下である。これらの観点から、第１疎水性有機溶媒と水溶性エチレン性不飽和単量体水溶液の体積比〔第１疎水性有機溶媒の体積（ｍＬ）／水溶性エチレン性不飽和単量体水溶液体積（ｍＬ）〕は、好ましくは１．０以上、より好ましくは１．０〜３．０、さらに好ましくは１．５〜２．５である。 The amount of the first hydrophobic organic solvent used is greatly related to the number and size of pores of the obtained porous water-absorbing polymer particles. The volume ratio of the first hydrophobic organic solvent and the water-soluble ethylenically unsaturated monomer aqueous solution [volume of the first hydrophobic organic solvent (mL) / water-soluble ethylenically unsaturated monomer aqueous solution volume (mL)] is: The obtained porous water-absorbing polymer particles are preferably 1.0 or more, more preferably 1.5 or more from the viewpoint of increasing the water absorption rate by forming continuous pores from the surface to the inside of the particles. Also, from the viewpoint of stabilizing the emulsification so that the water-soluble ethylenically unsaturated monomer aqueous solution can sufficiently contain the first hydrophobic organic solvent, it is preferably 3.0 or less, more preferably 2 .5 or less. From these viewpoints, the volume ratio of the first hydrophobic organic solvent to the water-soluble ethylenically unsaturated monomer aqueous solution [volume of the first hydrophobic organic solvent (mL) / volume of the water-soluble ethylenically unsaturated monomer aqueous solution ( mL)] is preferably 1.0 or more, more preferably 1.0 to 3.0, and still more preferably 1.5 to 2.5.
水溶性エチレン性不飽和単量体水溶液の２５℃における粘度は、Ｏ／Ｗエマルジョンを安定化させることにより、得られる粒子の多孔質性を高める観点から、好ましくは５００ｍＰａ・ｓ以上、より好ましくは１０００ｍＰａ・ｓ以上であり、単量体水溶液の攪拌や混合などの操作性を高める観点から、好ましくは３０００ｍＰａ・ｓ以下、より好ましくは２０００ｍＰａ・ｓ以下である。これらの観点から、水溶性エチレン性不飽和単量体水溶液の２５℃における粘度は、好ましくは５００〜３０００ｍＰａ・ｓ、より好ましくは１０００〜２０００ｍＰａ・ｓである。 The viscosity at 25 ° C. of the water-soluble ethylenically unsaturated monomer aqueous solution is preferably 500 mPa · s or more, more preferably from the viewpoint of enhancing the porosity of the particles obtained by stabilizing the O / W emulsion. From the viewpoint of enhancing the operability such as stirring and mixing of the aqueous monomer solution, it is preferably 3000 mPa · s or less, more preferably 2000 mPa · s or less. From these viewpoints, the viscosity of the water-soluble ethylenically unsaturated monomer aqueous solution at 25 ° C. is preferably 500 to 3000 mPa · s, more preferably 1000 to 2000 mPa · s.
水溶性エチレン性不飽和単量体水溶液の粘度は、例えば、高分子増粘剤を用いて調整することができる。 The viscosity of the water-soluble ethylenically unsaturated monomer aqueous solution can be adjusted using, for example, a polymer thickener.
高分子増粘剤としては、特に限定がないが、その使用量が少なくても比較的高い粘性が得られることから、例えば、ヒドロキシエチルセルロース、カルボキシメチルセルロース、グアーガム、グルコマンナン、デキストリン、部分中和ポリアクリル酸などが好ましく用いられる。 The polymer thickener is not particularly limited, but since a relatively high viscosity can be obtained even if the amount used is small, for example, hydroxyethylcellulose, carboxymethylcellulose, guar gum, glucomannan, dextrin, partially neutralized poly Acrylic acid or the like is preferably used.
Ｏ／Ｗエマルジョンは、例えば、高分子増粘剤、重合開始剤、架橋剤などを含む水溶性エチレン性不飽和単量体水溶液に、第１界面活性剤を混合し、得られた混合物を攪拌しながら、その中に第１疎水性有機溶媒を徐々に添加することにより、調製することができる。 In the O / W emulsion, for example, a first surfactant is mixed with a water-soluble ethylenically unsaturated monomer aqueous solution containing a polymer thickener, a polymerization initiator, a crosslinking agent, and the resulting mixture is stirred. However, it can be prepared by gradually adding the first hydrophobic organic solvent therein.
Ｏ／Ｗエマルジョンを調製する際の水溶性エチレン性不飽和単量体水溶液の液温は、Ｏ／Ｗエマルジョンの安定性の観点から、好ましくは２５℃以下、より好ましくは１０〜２０℃である。 The liquid temperature of the water-soluble ethylenically unsaturated monomer aqueous solution when preparing the O / W emulsion is preferably 25 ° C. or less, more preferably 10 to 20 ° C. from the viewpoint of the stability of the O / W emulsion. .
なお、Ｏ／Ｗエマルジョンを調製する際には、攪拌装置などを使用してもよい。攪拌装置には、特に限定がなく、例えば、ホモミキサーなどの微細に乳化しうる装置であってもよく、あるいはパドル型、プロペラ型、スクリュー型などの一般的な攪拌翼であってもよい。いずれの攪拌装置においても、攪拌速度等を調節することにより、得られる粒子の空孔の数や大きさを適宜調整することができる。 In preparing the O / W emulsion, a stirring device or the like may be used. The stirring device is not particularly limited, and may be a device capable of finely emulsifying such as a homomixer, or may be a general stirring blade such as a paddle type, a propeller type, or a screw type. In any stirring device, the number and size of the pores of the particles obtained can be appropriately adjusted by adjusting the stirring speed and the like.
次に、得られたＯ／Ｗエマルジョンを、第２界面活性剤を含有する第２疎水性有機溶媒に分散させることにより、Ｏ／Ｗ／Ｏエマルジョンが得られる。 Next, an O / W / O emulsion is obtained by dispersing the obtained O / W emulsion in a second hydrophobic organic solvent containing a second surfactant.
第２疎水性有機溶媒は、Ｏ／Ｗエマルジョンの分散媒である。第２疎水性有機溶媒としては、例えば、ｎ−ペンタン、ｎ−ヘキサン、ｎ−ヘプタン、ｎ−オクタン、シクロヘキサン、メチルシクロヘキサンなどの炭化水素系有機溶媒が好ましい。これらの中では、工業的に入手が容易で品質が安定しており、比較的安価であることから、ｎ−ヘキサン、ｎ−ヘプタンおよびシクロヘキサンがより好ましい。 The second hydrophobic organic solvent is a dispersion medium for the O / W emulsion. As the second hydrophobic organic solvent, for example, hydrocarbon organic solvents such as n-pentane, n-hexane, n-heptane, n-octane, cyclohexane and methylcyclohexane are preferable. Among these, n-hexane, n-heptane and cyclohexane are more preferable because they are easily available industrially, have stable quality, and are relatively inexpensive.
なお、第１疎水性有機溶媒および第２疎水性有機溶媒は、それぞれ同一種類であってもよく、あるいは異なる種類であってもよいが、両者が同一種類であることが、粒子の乾燥工程で回収した溶媒を再利用することが容易であるという観点から好ましい。 The first hydrophobic organic solvent and the second hydrophobic organic solvent may be the same type or different types, but the same type may be used in the particle drying step. This is preferable from the viewpoint of easy reuse of the recovered solvent.
第２界面活性剤としては、例えば、ソルビタン脂肪酸エステル、ショ糖脂肪酸エステル、（ポリ）グリセリン脂肪酸エステル、ソルビトール脂肪酸エステル、ポリオキシエチレンアルキルフェニルエーテルなどのノニオン系界面活性剤；脂肪酸塩、アルキルベンゼンスルホン酸塩、アルキルメチルタウリン酸塩、ポリオキシエチレンアルキルフェニルエーテル硫酸エステル塩、ポリオキシエチレンアルキルエーテルスルホン酸塩などのアニオン系界面活性剤などが挙げられ、これらは、それぞれ単独で用いてもよく、２種以上を混合して用いてもよい。これらの中では、安全性に優れていることから、ショ糖脂肪酸エステルが好ましい。 Examples of the second surfactant include nonionic surfactants such as sorbitan fatty acid ester, sucrose fatty acid ester, (poly) glycerin fatty acid ester, sorbitol fatty acid ester, polyoxyethylene alkylphenyl ether; fatty acid salt, alkylbenzene sulfonic acid And anionic surfactants such as salts, alkylmethyl taurates, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene alkyl ether sulfonates, etc., and these may be used alone, respectively. You may mix and use a seed | species or more. Of these, sucrose fatty acid esters are preferred because of their excellent safety.
なお、本明細書において、「（ポリ）」とは、「ポリ」の接頭語がある場合とない場合の双方を意味する。 In this specification, “(poly)” means both the case where there is a prefix of “poly” and the case where there is no prefix.
第２界面活性剤の使用量は、Ｏ／Ｗ／Ｏエマルジョンの重合中の安定性を確保する観点から、エチレン性不飽和単量体水溶液１００重量部に対して、好ましくは０．１重量部以上、より好ましくは０．３重量部以上であり、過剰量を添加しても、見あうだけの効果が得られず、かえって経済的でなくなる傾向があることから、エチレン性不飽和単量体水溶液１００重量部に対して、好ましくは３重量部以下、より好ましくは１重量部以下である。これらの観点から、第２界面活性剤の量は、エチレン性不飽和単量体水溶液１００重量部に対して、好ましくは０．１〜３重量部、より好ましくは０．３〜１重量部である。 The amount of the second surfactant used is preferably 0.1 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated monomer aqueous solution from the viewpoint of ensuring stability during polymerization of the O / W / O emulsion. More preferably, it is 0.3 parts by weight or more, and even if an excessive amount is added, an effect that can only be seen is not obtained, and on the contrary, there is a tendency that the ethylenically unsaturated monomer is not economical. The amount is preferably 3 parts by weight or less, more preferably 1 part by weight or less with respect to 100 parts by weight of the aqueous solution. From these viewpoints, the amount of the second surfactant is preferably 0.1 to 3 parts by weight, more preferably 0.3 to 1 part by weight with respect to 100 parts by weight of the ethylenically unsaturated monomer aqueous solution. is there.
Ｏ／Ｗ／Ｏエマルジョンを調製する方法としては、特に限定がないが、例えば、第２界面活性剤と、必要により高分子分散安定剤を含有させた第２疎水性有機溶媒中に、Ｏ／Ｗエマルジョンをチューブポンプなどの送液装置で送液し、攪拌しながら添加する方法などが挙げられる。攪拌の際に用いられる装置としては、特に限定がないが、例えば、フラスコ内で攪拌する際に用いるパドル型攪拌翼などを用いることができる。 The method for preparing the O / W / O emulsion is not particularly limited. For example, in the second hydrophobic organic solvent containing a second surfactant and, if necessary, a polymer dispersion stabilizer, O / Examples thereof include a method of feeding W emulsion with a liquid feeding device such as a tube pump and adding it while stirring. The apparatus used for stirring is not particularly limited. For example, a paddle type stirring blade used for stirring in a flask can be used.
Ｏ／Ｗ／Ｏエマルジョンの重合反応を行う際の反応温度は、用いられる重合開始剤の種類などによって異なるので、一概には決定することができないが、通常、重合反応を迅速に進行させ、重合時間を短くすることにより、経済性を高める一方で、第１もしくは第２の有機溶媒が沸騰しないように重合反応を行う観点から、好ましくは４０〜１００℃、より好ましくは５０〜８０℃である。 The reaction temperature for carrying out the polymerization reaction of the O / W / O emulsion varies depending on the type of polymerization initiator used, etc., and thus cannot be determined in general. From the viewpoint of carrying out the polymerization reaction so that the first or second organic solvent does not boil while shortening the time while improving economy, it is preferably 40 to 100 ° C., more preferably 50 to 80 ° C. .
なお、Ｏ／Ｗ／Ｏエマルジョンを６０℃以上で重合させる際には、重合時にＯ／Ｗ／Ｏエマルジョンの安定性を保つ観点から、高分子分散安定剤を用いることが好ましい。好適な高分子分散安定剤としては、マレイン酸変性ポリエチレンやアクリル酸変性ポリエチレンなどの酸変性ポリエチレンや、酸化ポリエチレン、エチレン−アクリル酸共重合体、エチレン−酢酸ビニル共重合体などが挙げられ、これらは、それぞれ単独でまたは併用してもよい。 When the O / W / O emulsion is polymerized at 60 ° C. or higher, it is preferable to use a polymer dispersion stabilizer from the viewpoint of maintaining the stability of the O / W / O emulsion during the polymerization. Suitable polymer dispersion stabilizers include acid-modified polyethylene such as maleic acid-modified polyethylene and acrylic acid-modified polyethylene, polyethylene oxide, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, and the like. May be used alone or in combination.
高分子分散安定剤の量は、重合時のＯ／Ｗ／Ｏエマルジョンを十分に安定化させるとともに、過剰量を添加しても見あうだけの効果が得られず、かえって経済的でなくなる傾向があることから、水溶性エチレン性不飽和単量体水溶液１００重量部に対して、好ましくは０．１〜３重量部、より好ましくは０．３〜１重量部である。 The amount of the polymer dispersion stabilizer stabilizes the O / W / O emulsion at the time of polymerization sufficiently, and even if an excessive amount is added, the effect that can be seen is not obtained, and it tends to be less economical. Therefore, the amount is preferably 0.1 to 3 parts by weight, more preferably 0.3 to 1 part by weight with respect to 100 parts by weight of the water-soluble ethylenically unsaturated monomer aqueous solution.
なお、Ｏ／Ｗ／Ｏエマルジョンの重合反応時間は、特に限定されないが、通常、０．５〜３時間程度である。 The polymerization reaction time of the O / W / O emulsion is not particularly limited, but is usually about 0.5 to 3 hours.
かくして多孔質吸水性ポリマー粒子が、通常、含水ゲル粒子の状態で得られるが、得られる吸水性ポリマー粒子の吸水速度およびゲル強度を高める観点から、後架橋反応を行うことが好ましい。 Thus, the porous water-absorbing polymer particles are usually obtained in the form of water-containing gel particles, but from the viewpoint of increasing the water absorption speed and gel strength of the water-absorbing polymer particles obtained, it is preferable to perform a post-crosslinking reaction.
後架橋反応の際に使用しうる後架橋剤としては、多孔質吸水性ポリマー粒子を構成している吸水性ポリマーの反応基と反応しうるものを用いることができる。 As the post-crosslinking agent that can be used in the post-crosslinking reaction, those capable of reacting with the reactive group of the water-absorbing polymer constituting the porous water-absorbing polymer particles can be used.
後架橋剤の具体例としては、エチレングリコール、プロピレングリコール、トリメチロールプロパン、グリセリン、（ポリ）オキシエチレングリコール、ポリオキシプロピレングリコール、ポリグリセリンなどのポリオール類；（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）プロピレングリコールジグリシジルエーテル、（ポリ）グリセリントリグリシジルエーテルなどの２個以上のグリシジル基をもつエーテル化合物；エピクロルヒドリン、エピブロムヒドリン、α―メチルエピクロルヒドリンなどのハロエポキシ化合物などの反応性官能基を２個以上有する化合物が挙げられ、これらは、それぞれ単独でまたは２種以上を混合して用いることができる。これらの中では、（ポリ）エチレングリコールジグリシジルエーテルが好ましい。 Specific examples of the post-crosslinking agent include ethylene glycol, propylene glycol, trimethylolpropane, glycerin, polyols such as (poly) oxyethylene glycol, polyoxypropylene glycol, polyglycerin; (poly) ethylene glycol diglycidyl ether, ( Poly (propylene glycol diglycidyl ether), (poly) glycerin triglycidyl ether and other ether compounds having two or more glycidyl groups; The compound which has 2 or more is mentioned, These can be used individually or in mixture of 2 or more types, respectively. Of these, (poly) ethylene glycol diglycidyl ether is preferred.
後架橋剤の使用量は、吸水性ポリマーの含水率や処理温度によって異なるので、一概には決定することができないが、吸水性ポリマーの表面近傍の架橋密度を充分に高める観点から、通常、水溶性エチレン性不飽和単量体１モルあたり、好ましくは０．０１ミリモル以上、より好ましくは０．１ミリモル以上であり、また、過剰量を添加しても見合う効果が得られず、かえって経済的でなくなる傾向があるため、好ましくは１０ミリモル以下、より好ましくは４ミリモル以下である。 The amount of the post-crosslinking agent used depends on the water content of the water-absorbing polymer and the treatment temperature, and thus cannot be determined in general. The amount is preferably 0.01 mmol or more, more preferably 0.1 mmol or more per 1 mol of the ethylenically unsaturated monomer, and even if an excessive amount is added, a suitable effect cannot be obtained. Therefore, it is preferably 10 mmol or less, more preferably 4 mmol or less.
後架橋剤の添加時期は、重合反応終了後であれば、いずれの時点で添加してもよいが、後架橋反応を充分に進行させ、吸水速度を高める観点から、吸水性ポリマーの含水率が１０質量％以上である時点が好ましく、２０質量％以上である時点がより好ましく、また、得られるポリマー粒子の保水能が低くなり過ぎないようにする観点から、吸水性ポリマーの含水率が８０質量％以下である時点が好ましく、６５質量％以下である時点がより好ましい。これらの観点から、後架橋剤の添加時期は、吸水性ポリマーの含水率が１０〜８０質量％である時点が好ましく、２０〜６５質量％である時点がより好ましい。 The post-crosslinking agent may be added at any time as long as it is after the completion of the polymerization reaction, but from the viewpoint of sufficiently promoting the post-crosslinking reaction and increasing the water absorption rate, the water content of the water-absorbing polymer is increased. The time point of 10% by mass or more is preferred, the time point of 20% by mass or more is more preferred, and the water content of the water-absorbing polymer is 80% by mass from the viewpoint of preventing the water retention ability of the resulting polymer particles from becoming too low. % Is preferable, and a time of 65% by mass or less is more preferable. From these viewpoints, the time when the post-crosslinking agent is added is preferably a time when the water content of the water-absorbing polymer is from 10 to 80% by mass, and more preferably from 20 to 65% by mass.
なお、本発明における含水率とは、吸水性ポリマーの固形分に対して、含水ゲル（水を含んだ状態の吸水性ポリマー）に含まれている水分量の比率を示した数値であり、式：
〔含水率（質量％）〕
＝〔（含水ゲル中の水分量）÷（吸水性ポリマーの固形分）〕×１００
に基づいて、求めることができる。
The water content in the present invention is a numerical value indicating the ratio of the amount of water contained in the water-containing gel (water-absorbing polymer containing water) to the solid content of the water-absorbing polymer. :
[Moisture content (mass%)]
= [(Moisture content in hydrous gel) / (solid content of water-absorbing polymer)] x 100
On the basis of
なお、含水ゲル中の水分量およびその固形分は、重合反応における単量体などの原料化合物の仕込み量と、脱水工程以降において除去された水分量とから、算出することができる。 The amount of water in the hydrogel and its solid content can be calculated from the amount of raw material compounds such as monomers in the polymerization reaction and the amount of water removed after the dehydration step.
後架橋反応は、例えば、重合反応終了後の含水ゲルを、乾燥するなどして脱水し、所定の含水率に調整した後、後架橋剤を０．５〜５０質量％の水やアルコールの溶液として添加することによって行うことができる。後架橋剤を添加した直後に乾燥させてもよいが、内温を５０〜９０℃で０．５〜６時間保持し、後架橋反応を促進させることがより好ましい。 The post-crosslinking reaction is performed by, for example, drying the water-containing gel after completion of the polymerization reaction to adjust the water content to a predetermined water content, and then adding 0.5 to 50% by mass of water or alcohol solution of the post-crosslinking agent. Can be added as Although it may be dried immediately after the addition of the post-crosslinking agent, it is more preferable to maintain the internal temperature at 50 to 90 ° C. for 0.5 to 6 hours to promote the post-crosslinking reaction.
後架橋反応の終了後には、公知の方法で水や疎水性有機溶媒を留去することにより、多孔質吸水性ポリマー粒子を得ることができる。 After completion of the post-crosslinking reaction, porous water-absorbing polymer particles can be obtained by distilling off water and the hydrophobic organic solvent by a known method.
本発明の製造法によって得られた多孔質吸水性ポリマー粒子の嵩密度は、例えば、十分な機械的強度を有し、生理用ナプキンなどの吸収体の製造時に、多孔質吸水性ポリマー粒子が破砕するのを防止する観点から、０．３０ｇ／ｍＬ以上、好ましくは０．３５ｇ／ｍＬ以上であり、独立空孔の生成を抑制し、表面と連通した連続空孔を形成させることにより、吸水性ポリマーの実質的な表面積を大きくし、吸水速度を高める観点から、０．５０ｇ／ｍＬ以下、好ましくは、０．４５ｇ／ｍＬ以下である。これらの観点から、多孔質吸水性ポリマー粒子の嵩密度は、０．３０〜０．５０ｇ／ｍＬ、好ましくは０．３５〜０．４５ｇ／ｍＬである。 The bulk density of the porous water-absorbing polymer particles obtained by the production method of the present invention has, for example, sufficient mechanical strength, and the porous water-absorbing polymer particles are crushed during the production of an absorbent body such as a sanitary napkin. From the standpoint of preventing the above, it is 0.30 g / mL or more, preferably 0.35 g / mL or more, and suppresses the generation of independent vacancies and forms continuous vacancies in communication with the surface, thereby absorbing water. From the viewpoint of increasing the substantial surface area of the polymer and increasing the water absorption rate, it is 0.50 g / mL or less, preferably 0.45 g / mL or less. From these viewpoints, the bulk density of the porous water-absorbing polymer particles is 0.30 to 0.50 g / mL, preferably 0.35 to 0.45 g / mL.
また、得られた多孔質吸水性ポリマー粒子の平均粒子径は、特に限定されないが、粉体としての取扱い性を良好にするとともに、吸水性ポリマー粒子の好適な吸水速度を確保する観点から、通常、１００〜４００μｍであることが好ましい。 Further, the average particle diameter of the obtained porous water-absorbing polymer particles is not particularly limited, but usually from the viewpoint of improving the handleability as a powder and ensuring a suitable water absorption rate of the water-absorbing polymer particles. 100 to 400 μm is preferable.
かくして得られた多孔質吸水性ポリマー粒子は、例えば、紙オムツ、生理用ナプキン、失禁パッド、ペットシートなどに好適に使用しうるものである。 The porous water-absorbing polymer particles thus obtained can be suitably used for, for example, paper diapers, sanitary napkins, incontinence pads, pet sheets and the like.
次に、本発明を実施例に基づいてさらに詳細に説明するが、本発明は、かかる実施例のみに限定されるものではない。 Next, the present invention will be described in more detail based on examples. However, the present invention is not limited to such examples.
実施例１
（１）Ｏ／Ｗエマルジョンの調製
攪拌機、冷却管、滴下ロート、窒素ガス吹き込み用フッ素樹脂製チューブおよび温度計を備えた１０００ｍＬ容の五ツ口円筒形丸底フラスコに、８０質量％アクリル酸９２．０ｇ（１．０２モル）とイオン交換水８．０２ｇを仕込み、内温が１５〜２０℃となるようにフラスコを外部から冷却しつつ、滴下ロートより３０質量％水酸化ナトリウム１０２．２ｇ（０．７７モル）を攪拌しながら滴下して中和を行い、アクリル酸を中和度が７５モル％となるように中和した。
Example 1
(1) Preparation of O / W Emulsion Into a 1000 mL five-necked cylindrical round bottom flask equipped with a stirrer, a condenser tube, a dropping funnel, a fluororesin tube for blowing nitrogen gas and a thermometer, 80% by mass acrylic acid 92 0.02 g (1.02 mol) and 8.02 g of ion-exchanged water were charged, and the flask was cooled from the outside so that the internal temperature became 15 to 20 ° C., while 102.2 g of 30 mass% sodium hydroxide was added from the dropping funnel ( 0.77 mol) was added dropwise with stirring to effect neutralization, and acrylic acid was neutralized so that the degree of neutralization was 75 mol%.
この中和したアクリル酸水溶液を室温（２３±２℃）に保ち、増粘剤のヒドロキシエチルセルロース１．８ｇを投入し、攪拌下で溶解した。さらに、この水溶液に第１界面活性剤としてポリオキシエチレン−ポリオキシプロピレン共重合体〔旭電化（株）製、商品名：アデカプルロニックＦ−１０８、質量平均分子量：１５５００、ポリオキシエチレンの含有量：８０質量％〕１．８ｇをイオン交換水３０．０ｇに溶解させた溶液、過硫酸カリウム０．１ｇ（０．３７ミリモル）、エチレングリコールジグリシジルエーテル０．０２ｇ（０．１１ミリモル）およびイオン交換水１０．０６ｇを加えて混合・溶解させ、単量体水溶液を調製した。この単量体水溶液の２５℃における粘度は、１４００ｍＰａ・ｓであった。 The neutralized acrylic acid aqueous solution was kept at room temperature (23 ± 2 ° C.), and 1.8 g of thickening agent hydroxyethyl cellulose was added and dissolved under stirring. Furthermore, a polyoxyethylene-polyoxypropylene copolymer (manufactured by Asahi Denka Co., Ltd., trade name: Adeka Pluronic F-108, mass average molecular weight: 15500, polyoxyethylene content as a first surfactant in this aqueous solution : 80% by mass] a solution of 1.8 g in ion-exchanged water 30.0 g, potassium persulfate 0.1 g (0.37 mmol), ethylene glycol diglycidyl ether 0.02 g (0.11 mmol) and ions A monomer aqueous solution was prepared by adding 10.06 g of exchange water and mixing and dissolving. The viscosity of this aqueous monomer solution at 25 ° C. was 1400 mPa · s.
次に、フラスコを外部から冷却しながら内温を１５±２℃に保ち、パドル型攪拌翼を用いて回転数４００ｒｐｍでこの単量体水溶液を攪拌しながら、ｎ−ヘプタン２６６ｇ（約４００ｍＬ）をチューブポンプにて３０ｍＬ／分の流量で投入し、ｎ−ヘプタンを上記単量体水溶液に内包させたＯ／Ｗエマルジョンを調製した。 Next, while cooling the flask from the outside, maintaining the internal temperature at 15 ± 2 ° C., and stirring the aqueous monomer solution at a rotational speed of 400 rpm using a paddle type stirring blade, 266 g (about 400 mL) of n-heptane was added. An O / W emulsion in which n-heptane was encapsulated in the monomer aqueous solution was prepared using a tube pump at a flow rate of 30 mL / min.
（２）Ｏ／Ｗ／Ｏエマルジョンの調製
攪拌機、還流冷却管、窒素ガス吹き込み用フッ素樹脂製チューブ、Ｏ／Ｗエマルジョン投入用フッ素樹脂製チューブおよび温度計を備えた１０００ｍＬ容の五ツ口円筒形丸底フラスコ内に、ｎ−ヘプタン２００ｇ（約３００ｍＬ）を注ぎ、第２界面活性剤としてショ糖脂肪酸エステル〔三菱化学フーズ（株）製、商品名：Ｓ−３７０〕０．９ｇと、高分子分散安定剤として無水マレイン酸変性ポリエチレン〔三井化学（株）、商品名：ＨＩ−ＷＡＸ１１０５Ａ〕０．９ｇとを添加し、攪拌しながら８０℃まで昇温し、溶解した後に６０℃まで放冷した。攪拌機の回転数を６００ｒｐｍとし、６０℃になった時点でフラスコ系内の酸素を除去するために窒素ガスを５０ｍＬ／分の流量で吹き込みながら、前記（１）で得られたＯ／Ｗエマルジョンをチューブポンプにて６０ｍＬ／分の流量で滴下し、Ｏ／Ｗ／Ｏエマルジョンを調製した。
(2) Preparation of O / W / O emulsion 1000 mL capacity five-necked cylinder equipped with stirrer, reflux condenser, fluororesin tube for nitrogen gas blowing, fluororesin tube for charging O / W emulsion, and thermometer In a round bottom flask, pour 200 g (about 300 mL) of n-heptane, 0.9 g of sucrose fatty acid ester [Mitsubishi Chemical Foods, trade name: S-370] as a second surfactant, polymer 0.9 g of maleic anhydride-modified polyethylene [Mitsui Chemicals Co., Ltd., trade name: HI-WAX1105A] was added as a dispersion stabilizer, the temperature was raised to 80 ° C. with stirring, the solution was dissolved, and then allowed to cool to 60 ° C. . The rotation speed of the stirrer was set to 600 rpm, and when the temperature reached 60 ° C., nitrogen gas was blown at a flow rate of 50 mL / min to remove oxygen in the flask system, and the O / W emulsion obtained in (1) was An O / W / O emulsion was prepared by dropwise addition with a tube pump at a flow rate of 60 mL / min.
（３）重合〜乾燥
前記（２）で得られたＯ／Ｗ／Ｏエマルジョン入りのフラスコを７０℃の湯浴に浸漬し昇温させ、重合反応を１．５時間行った。その後、窒素ガスの通気を止めて１２０℃の油浴に切り換え、共沸蒸留により水のみを系外に除去し、脱水を行った。
(3) Polymerization to drying The flask containing the O / W / O emulsion obtained in the above (2) was immersed in a 70 ° C. hot water bath to raise the temperature, and the polymerization reaction was carried out for 1.5 hours. Thereafter, the ventilation of nitrogen gas was stopped and the oil bath was switched to 120 ° C., and only water was removed from the system by azeotropic distillation, followed by dehydration.
含水率が３０質量％となるまで脱水した後、２質量％エチレングリコールジグリシジルエーテル水溶液４．６０ｇ（０．５３ミリモル）を添加し、内温を８０℃に保ちつつ２時間反応させた。再び１２０℃の油浴にて加熱し、分散媒のｎ−ヘプタンおよび水を蒸留により除去して乾燥し、得られた粒子を目開きが８５０μｍの篩に通して粗粒子を取り除き、平均粒子径が３９５μｍの多孔質吸水性ポリマー粒子８７ｇを得た。得られた多孔質吸水性ポリマー粒子の電子顕微鏡写真を図１に示す。なお、図１において、拡大の尺度は、図１の下欄外に示されている。 After dehydration until the water content became 30% by mass, 4.60 g (0.53 mmol) of 2% by mass ethylene glycol diglycidyl ether aqueous solution was added, and the mixture was reacted for 2 hours while maintaining the internal temperature at 80 ° C. The mixture is heated again in an oil bath at 120 ° C., the dispersion medium n-heptane and water are removed by distillation and dried. The resulting particles are passed through a sieve having an opening of 850 μm to remove coarse particles, and the average particle size As a result, 87 g of porous water-absorbing polymer particles having a particle diameter of 395 μm were obtained. An electron micrograph of the obtained porous water-absorbing polymer particles is shown in FIG. In FIG. 1, the scale of enlargement is shown in the lower column of FIG.
実施例２
実施例１において、第１界面活性剤として、ポリオキシエチレン−ポリオキシプロピレン共重合体〔旭電化（株）製、商品名：アデカプルロニックＦ−１０８〕の代わりに、ポリオキシエチレン−ポリオキシプロピレン共重合体〔旭電化（株）製、商品名：アデカプルロニックＰ−８５、質量平均分子量：４６００、ポリオキシエチレン含有量：５０質量％〕１．８ｇを用い、また、Ｏ／Ｗエマルジョンを調製する際に、単量体水溶液をホモミキサーにて回転数８００ｒｐｍで攪拌した以外は、実施例１と同様にして多孔質吸水性ポリマー粒子を調製した。得られた粒子を目開きが８５０μｍの篩に通して平均粒子径３１０μｍの多孔質吸水性ポリマー粒子８３ｇを得た。
Example 2
In Example 1, polyoxyethylene-polyoxypropylene was used as the first surfactant instead of polyoxyethylene-polyoxypropylene copolymer [Asahi Denka Co., Ltd., trade name: Adeka Pluronic F-108]. 1.8 g of a copolymer [Asahi Denka Co., Ltd., trade name: Adeka Pluronic P-85, mass average molecular weight: 4600, polyoxyethylene content: 50 mass%] was used, and an O / W emulsion was prepared. In this case, porous water-absorbing polymer particles were prepared in the same manner as in Example 1 except that the monomer aqueous solution was stirred with a homomixer at a rotation speed of 800 rpm. The obtained particles were passed through a sieve having an opening of 850 μm to obtain 83 g of porous water-absorbing polymer particles having an average particle diameter of 310 μm.
実施例３
実施例１において、増粘剤のヒドロキシエチルセルロースの量を１．２ｇに変更し、Ｏ／Ｗエマルジョン調製時の攪拌機の回転数を１０００ｒｐｍに変更した以外は、実施例１と同様にして多孔質吸水性ポリマー粒子を調製した。なお、使用した単量体水溶液の２５℃における粘度は６００ｍＰａ・ｓであった。得られた粒子を目開きが８５０μｍの篩に通して平均粒子径４０３μｍの多孔質吸水性ポリマー粒子８０ｇを得た。
Example 3
In Example 1, the amount of hydroxyethyl cellulose as a thickener was changed to 1.2 g, and the porous water absorption was performed in the same manner as in Example 1 except that the rotation speed of the stirrer during preparation of the O / W emulsion was changed to 1000 rpm. Polymer particles were prepared. The viscosity of the aqueous monomer solution used at 25 ° C. was 600 mPa · s. The obtained particles were passed through a sieve having an opening of 850 μm to obtain 80 g of porous water-absorbing polymer particles having an average particle diameter of 403 μm.
実施例４
実施例１において、水溶性エチレン性不飽和単量体水溶液に内包させるヘプタン量を３３５ｇ（約５００ｍＬ）に変更した以外は、実施例１と同様にして多孔質吸水性ポリマー粒子を調製した。得られた粒子を目開きが８５０μｍの篩に通して平均粒子径３６３μｍの多孔質吸水性ポリマー粒子８２ｇを得た。得られた多孔質吸水性ポリマー粒子の電子顕微鏡写真を図２に示す。なお、図２において、拡大の尺度は、図２の下欄外に示されている。
Example 4
In Example 1, porous water-absorbing polymer particles were prepared in the same manner as in Example 1 except that the amount of heptane included in the water-soluble ethylenically unsaturated monomer aqueous solution was changed to 335 g (about 500 mL). The obtained particles were passed through a sieve having an opening of 850 μm to obtain 82 g of porous water-absorbing polymer particles having an average particle diameter of 363 μm. An electron micrograph of the obtained porous water-absorbing polymer particles is shown in FIG. In FIG. 2, the scale of enlargement is shown in the lower column of FIG.
比較例１
実施例１において、第１界面活性剤として、ポリオキシエチレン−ポリオキシプロピレンブロック共重合体の代わりに、アルキルアリルポリエーテルアルコール〔和光純薬工業（株）製、登録商標：Ｔｒｉｔｏｎ Ｘ−４０５〕１．８ｇを用いた以外は、実施例１と同様の操作を行ったところ、重合反応の際に、Ｏ／Ｗ／Ｏエマルジョンの不安定化が生じ、不定形粒子が得られた。得られた粒子を目開きが８５０μｍの篩に通して平均粒子径３３７μｍの不定形吸水性ポリマー粒子８６ｇを得た。得られた不定形吸水性ポリマー粒子の電子顕微鏡写真を図３に示す。なお、図３において、拡大の尺度は、図３の下欄外に示されている。
Comparative Example 1
In Example 1, instead of polyoxyethylene-polyoxypropylene block copolymer, alkylallyl polyether alcohol (manufactured by Wako Pure Chemical Industries, Ltd., registered trademark: Triton X-405) was used as the first surfactant. When the same operation as in Example 1 was carried out except that 1.8 g was used, the O / W / O emulsion was destabilized during the polymerization reaction, and amorphous particles were obtained. The obtained particles were passed through a sieve having an opening of 850 μm to obtain 86 g of amorphous water-absorbing polymer particles having an average particle diameter of 337 μm. An electron micrograph of the obtained amorphous water-absorbing polymer particles is shown in FIG. In FIG. 3, the scale of enlargement is shown in the lower column of FIG.
比較例２
実施例１において、第１界面活性剤として、ポリオキシエチレン−ポリオキシプロピレンブロック共重合体の代わりに、ショ糖脂肪酸エステル〔三菱化学フーズ（株）製、商品名：Ｓ−１６７０〕１．８ｇを用いた以外は、実施例１と同様の操作を行ったところ、不定形粒子が得られた。得られた粒子を目開きが８５０μｍの篩に通して平均粒子径４２０μｍの不定形吸水性ポリマー粒子７０ｇを得た。
Comparative Example 2
In Example 1, in place of the polyoxyethylene-polyoxypropylene block copolymer, 1.8 g of sucrose fatty acid ester [manufactured by Mitsubishi Chemical Foods, Inc., trade name: S-1670] was used as the first surfactant. When the same operation as in Example 1 was performed except that was used, amorphous particles were obtained. The obtained particles were passed through a sieve having an opening of 850 μm to obtain 70 g of amorphous water-absorbing polymer particles having an average particle diameter of 420 μm.
比較例３
実施例１において、第１界面活性剤として、ポリオキシエチレン−ポリオキシプロピレンブロック共重合体の代わりに、ポリオキシエチレン（５）ラウリルエーテル〔日本エマルジョン（株）製、商品名:ＥＭＡＬＥＸ−７０５〕１．８ｇを用いた以外は、実施例１と同様の操作を行ったところ、中空の球状粒子が得られた。得られた球状粒子を目開きが８５０μｍの篩に通して平均粒子径３７０μｍの球状吸水性ポリマー粒子８４ｇを得た。得られた球状吸水性ポリマー粒子の電子顕微鏡写真を図４に示す。なお、図４において、拡大の尺度は、図４の下欄外に示されている。
Comparative Example 3
In Example 1, as the first surfactant, instead of polyoxyethylene-polyoxypropylene block copolymer, polyoxyethylene (5) lauryl ether [manufactured by Nippon Emulsion Co., Ltd., trade name: EMALEX-705] Except that 1.8 g was used, the same operation as in Example 1 was performed, and hollow spherical particles were obtained. The obtained spherical particles were passed through a sieve having an opening of 850 μm to obtain 84 g of spherical water-absorbing polymer particles having an average particle diameter of 370 μm. An electron micrograph of the obtained spherical water-absorbing polymer particles is shown in FIG. In FIG. 4, the scale of enlargement is shown in the lower column of FIG.
比較例４
実施例１において、第１界面活性剤としてポリオキシエチレン−ポリオキシプロピレンブロック共重合体の代わりに、部分ケン化ポリビニルアルコール〔日本合成化学工業（株）製、品番:ＧＨ−１７〕１．８ｇを用い、内包させるｎ−ヘプタンの量を１３３ｇ（約２００ｍＬ）に変更した以外は、実施例１と同様の操作を行ったところ、内部に独立空孔を持つ球状粒子が得られた。得られた球状粒子を目開きが８５０μｍの篩に通して平均粒子径４１０μｍの球状吸水性ポリマー粒子８０ｇを得た。得られた球状吸水性ポリマー粒子の電子顕微鏡写真を図５に示す。なお、図５において、拡大の尺度は、図５の下欄外に示されている。
Comparative Example 4
In Example 1, instead of polyoxyethylene-polyoxypropylene block copolymer as the first surfactant, partially saponified polyvinyl alcohol [manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product number: GH-17] 1.8 g The same procedure as in Example 1 was performed except that the amount of n-heptane to be encapsulated was changed to 133 g (about 200 mL), and spherical particles having independent pores inside were obtained. The obtained spherical particles were passed through a sieve having an opening of 850 μm to obtain 80 g of spherical water-absorbing polymer particles having an average particle diameter of 410 μm. An electron micrograph of the obtained spherical water-absorbing polymer particles is shown in FIG. In FIG. 5, the scale of enlargement is shown in the lower column of FIG.
比較例５
１００ｍＬ容の三角フラスコ内に、アクリル酸１１．０ｇと３０％水酸化ナトリウム水溶液１５．２ｇとを冷却しながら混合することにより、アクリル酸を中和し、イオン交換水３．８ｇを加えて単量体水溶液を調製した。この単量体水溶液に、界面活性剤〔和光純薬工業（株）製、商品名：Ｔｒｉｔｏｎ Ｘ−４０５〕１０ｇと部分中和ポリビニルアルコール〔（株）クラレ製、品番:Ｌ−８〕の２％水溶液２５ｇを混合し、均一な組成となるまで攪拌した。
Comparative Example 5
In a 100 mL Erlenmeyer flask, 11.0 g of acrylic acid and 15.2 g of 30% aqueous sodium hydroxide solution were mixed while cooling to neutralize the acrylic acid, and 3.8 g of ion-exchanged water was added. A meter aqueous solution was prepared. To this aqueous monomer solution, 10 g of a surfactant [manufactured by Wako Pure Chemical Industries, Ltd., trade name: Triton X-405] and partially neutralized polyvinyl alcohol [manufactured by Kuraray Co., Ltd., product number: L-8] 2 25% aqueous solution was mixed and stirred until a uniform composition was obtained.
得られた単量体水溶液を１Ｌ容のビーカー内に移し、約１５℃の温度に保ちつつ、トルエン２６０ｇ（約３００ｍＬ）をゆっくりと加えながら、ホモミキサーにて回転数６０００ｒｐｍで攪拌し、Ｏ／Ｗエマルジョンを調製した。 The obtained monomer aqueous solution was transferred into a 1 L beaker, and while maintaining the temperature at about 15 ° C., 260 g (about 300 mL) of toluene was slowly added, and the mixture was stirred with a homomixer at a rotational speed of 6000 rpm. A W emulsion was prepared.
一方、攪拌機、還流冷却管、窒素吹き込み用フッ素樹脂製チューブ、Ｏ／Ｗエマルジョン投入用フッ素樹脂製チューブおよび温度計を備えた１０００ｍＬ容の五ツ口円筒形丸底フラスコ内に、分散媒としてジクロロメタン５８４ｇを入れ、エチルセルロース〔日新化成（株）、グレード：ＳＴＤ型（４５ｃｐｓ）〕１２ｇを加えて回転数１５０ｒｐｍで攪拌しながら４０℃で溶解させ、１５分間程度窒素ガスを１００ｍＬ／分の流速で吹き込んで系内の酸素を除去した。この分散媒を２０℃まで冷却した後、回転数１５０ｒｐｍで攪拌しながら、前記で得られたＯ／Ｗエマルジョンをチューブポンプにて６０ｍＬ／分の流速で滴下して分散させた。 On the other hand, in a 1000 mL five-necked cylindrical round bottom flask equipped with a stirrer, a reflux condenser, a fluorine resin tube for blowing nitrogen, a fluorine resin tube for introducing O / W emulsion, and a thermometer, dichloromethane was used as a dispersion medium. Add 584 g, add 12 g of ethylcellulose [Nisshin Kasei Co., Ltd., grade: STD type (45 cps)] and dissolve at 40 ° C. with stirring at 150 rpm, and nitrogen gas at a flow rate of 100 mL / min for about 15 minutes. The oxygen in the system was removed by blowing. After cooling this dispersion medium to 20 ° C., the O / W emulsion obtained above was dropped and dispersed with a tube pump at a flow rate of 60 mL / min while stirring at a rotation speed of 150 rpm.
この分散液に窒素ガスを更に１００ｍＬ／分の流速で１０分間吹き込んだ後、２％亜硫酸水素ナトリウム水溶液０．５ｇおよび２％塩化鉄(III)六水和物水溶液０．５ｇを加えて回転数１８０ｒｐｍで攪拌しながら約２３℃で６時間重合反応を行った。さらに、４０℃の水浴で２時間加温した。 Nitrogen gas was further blown into the dispersion at a flow rate of 100 mL / min for 10 minutes, 0.5 g of 2% aqueous sodium hydrogen sulfite solution and 0.5 g of 2% iron (III) chloride hexahydrate aqueous solution were added, and the number of revolutions was increased. While stirring at 180 rpm, the polymerization reaction was performed at about 23 ° C. for 6 hours. Furthermore, it was heated in a 40 ° C. water bath for 2 hours.
得られた含水ゲルを分散液のままメタノール１２００ｇに投入し、粒子を再沈澱させ、目開きが７５μｍの篩で濾別した。この粒子をアセトンによるソクスレー抽出を３時間行い、ついでメタノールによるソクスレー抽出を３時間行い精製した後、真空乾燥器を用いて５０℃で２時間乾燥させ、平均粒子径２０８μｍのサンプル１１ｇを得た。得られた吸水性ポリマー粒子の電子顕微鏡写真を図６に示す。なお、図６において、拡大の尺度は、図６の下欄外に示されている。 The obtained water-containing gel was put into 1200 g of methanol as a dispersion to reprecipitate the particles, and was filtered by a sieve having an opening of 75 μm. The particles were subjected to Soxhlet extraction with acetone for 3 hours and then purified by Soxhlet extraction with methanol for 3 hours, followed by drying at 50 ° C. for 2 hours using a vacuum dryer to obtain 11 g of a sample having an average particle size of 208 μm. An electron micrograph of the water-absorbing polymer particles obtained is shown in FIG. In FIG. 6, the scale of enlargement is shown in the lower column of FIG.
次に、各実施例および各比較例で得られた吸水性ポリマー粒子の物性を以下の測定方法にしたがって調べた。その結果を表１に示す。 Next, the physical properties of the water-absorbing polymer particles obtained in each Example and each Comparative Example were examined according to the following measuring method. The results are shown in Table 1.
（１）保水能
吸水性ポリマー粒子２．００ｇを綿袋（メンブロード６０番、横１０ｃｍ×縦２０ｃｍ）中に量りとり、５００ｍＬ容のビーカー中に入れた。綿袋内に生理食塩水（０．９％水酸化ナトリウム水溶液）５００ｍＬを一度に注ぎ込み、吸水性ポリマー粒子にママコが生じないように分散させた後、綿袋の上部を輪ゴムで縛り、1時間放置して、吸水性ポリマー粒子を十分に膨潤させた。
(1) Water retention ability 2.00 g of water-absorbing polymer particles were weighed into a cotton bag (Menbroad No. 60, width 10 cm × length 20 cm) and placed in a 500 mL beaker. Pour 500 mL of physiological saline (0.9% sodium hydroxide aqueous solution) into the cotton bag at once and disperse the water-absorbing polymer particles so as not to cause mamako, and then tie the upper part of the cotton bag with a rubber band for 1 hour. The water-absorbing polymer particles were sufficiently swollen by allowing them to stand.
次に、遠心力が１６７Ｇとなるように設定した脱水機〔国産遠心（株）製、品番：Ｈ−１２２〕を用いて、前記綿袋を１分間脱水し、脱水後の膨潤ポリマーを含んだ綿袋の質量（Ｗａ）を測定した。また、綿袋に吸水性ポリマー粒子を入れずに同様の操作を行い、脱水後の綿袋のみの湿潤空質量（Ｗｂ）を測定し、式：
〔保水能（ｇ／ｇ）〕＝〔Ｗａ−Ｗｂ（ｇ）〕÷〔吸水性ポリマー粒子の仕込み質量（ｇ）〕
にしたがって、保水能を求めた。
Next, the cotton bag was dehydrated for 1 minute using a dehydrator (manufactured by Kokusan Centrifugal Co., Ltd., product number: H-122) set so that the centrifugal force was 167 G, and the swollen polymer after dehydration was included. The mass (Wa) of the cotton bag was measured. Further, the same operation was performed without putting the water-absorbing polymer particles in the cotton bag, and the wet empty mass (Wb) of only the cotton bag after dehydration was measured.
[Water retention capacity (g / g)] = [Wa−Wb (g)] ÷ [Mass of water-absorbing polymer particles (g)]
The water retention capacity was calculated according to
（２）吸水速度
１００ｍＬ容のビーカー内に、生理食塩水５０±０．０１ｇを量りとり、２５±０．２℃の温度の恒温水槽に１時間浸漬して恒温にした後、スターラーチップ（８ｍｍφ×３０ｍｍ）を投入し、マグネチックスターラー〔イウチ（Iuchi）社製、品番：ＨＳ−３０Ｄ〕の上に配置した。その後、スターラーチップが回転数６００ｒｐｍで回転するように調整し、さらに、スターラーチップの回転により生ずる渦の底部がスターラーチップの上部近くに位置するように調整した。
(2) Water absorption rate In a 100 mL beaker, 50 ± 0.01 g of physiological saline was weighed and immersed in a constant temperature water bath at a temperature of 25 ± 0.2 ° C. for 1 hour. × 30 mm) was placed and placed on a magnetic stirrer (Iuchi, product number: HS-30D). Thereafter, the stirrer tip was adjusted to rotate at a rotational speed of 600 rpm, and further adjusted so that the bottom of the vortex generated by the rotation of the stirrer tip was located near the top of the stirrer tip.
次に、あらかじめ５００〜３００μｍに分級しておいた吸水性ポリマー粒子２．０±０．００２ｇを、ビーカー内の渦の中央部分とビーカーの側面との間に素早く投入し、投入した時点から渦が収束した時点までの時間（秒）を、ストップウォッチを用いて測定し、吸水速度とした。 Next, 2.0 ± 0.002 g of the water-absorbing polymer particles classified in advance to 500 to 300 μm is quickly put between the central part of the vortex in the beaker and the side surface of the beaker, and the vortex is started from the time of the addition. The time (seconds) until the point of convergence was measured using a stopwatch, and was taken as the water absorption rate.
（３）嵩密度
吸水性ポリマー粒子の嵩密度は、ＪＩＳ Ｋ−６７２０−２に記載の「かさ比重測定装置」を用いて測定した。吸水性ポリマー粒子約１２０ｍＬを、ダンパーで底部を塞いだ前記装置の漏斗部分に入れ、ダンパーより３８ｍｍ下に９０ｍＬ容（内径４０ｍｍφ、円筒形状）の受器を設置した状態で、前記装置のダンパーを速やかに引き抜いて、吸水性ポリマー粒子を受器に落とした。
(3) Bulk density The bulk density of the water-absorbing polymer particles was measured using a “bulk specific gravity measuring device” described in JIS K-6720-2. About 120 mL of water-absorbing polymer particles are placed in the funnel portion of the device whose bottom is closed with a damper, and a damper of 90 mL (inner diameter 40 mmφ, cylindrical shape) is installed 38 mm below the damper, and the damper of the device is installed. The water-absorbing polymer particles were dropped quickly into the receiver.
次に、受器から盛り上がった吸水性ポリマー粒子をガラス棒で、受器の開口部に対して水平にすり落とした後、受器ごと重量Ｗ１（ｇ）を測定した。別途、空状態の受器の重量Ｗ０（ｇ）を測定しておき、重量Ｗ１（ｇ）から重量Ｗ０（ｇ）を引いた吸水性ポリマー粒子の重量を、受器の体積（Ｖ＝９０ｍＬ）で除した値Ｓ（ｇ／ｍＬ）を求めた。値Ｓを求めるときの数式を以下に示す。
Ｓ（ｇ／ｍＬ）＝［Ｗ１−Ｗ０］（ｇ）／Ｖ（ｍＬ）
Next, after water-absorbing polymer particles rising from the receiver were scraped horizontally with a glass rod with respect to the opening of the receiver, the weight W1 (g) of the entire receiver was measured. Separately, the weight W0 (g) of the empty receiver was measured, and the weight of the water-absorbing polymer particles obtained by subtracting the weight W0 (g) from the weight W1 (g) was determined as the volume of the receiver (V = 90 mL). The value S (g / mL) divided by was determined. Formulas for obtaining the value S are shown below.
S (g / mL) = [W1-W0] (g) / V (mL)
測定した吸水性ポリマー粒子を回収し、前記と同様にして合計３回の値Ｓを測定し、その平均値を嵩密度とした。 The measured water-absorbing polymer particles were collected, and the value S was measured three times in the same manner as described above, and the average value was taken as the bulk density.
（４）平均粒子径
吸水性ポリマー粒子５０ｇを秤量し、これをＪＩＳ Ｚ８８０１−１９８２対応の８つの標準篩（上から順に、目開きが８５０μｍ、５００μｍ、３５５μｍ、３００μｍ、２５０μｍ、１８０μｍ、１０６μｍの篩および底容器を順に積み重ねたもの）の一番上の篩に吸水性ポリマー粒子を入れ、ロータップ式篩振動機を用いて１０分間振動させて篩い分けした後、篩ごとに秤量し、その結果に基づいて積算質量が５０％となる粒子径を平均粒子径とし、式：
〔平均粒子径〕＝[（５０−Ａ）/（Ｄ−Ａ）]×（Ｃ−Ｂ）＋Ｂ
〔式中、Ａは粒度分布の粗い方から順次質量を積算し、積算質量が５０質量％未満であり、かつ５０質量％に最も近い点の積算値を求めたときの当該積算値（ｇ）、Ｂは前記積算値を求めたときの目開き（μｍ）、Ｄは粒度分布の粗い方から順次質量を積算し、積算質量が５０質量％以上であり、かつ５０質量％に最も近い点の積算値を求めたときの積算値（ｇ）、Ｃは前記積算値を求めたときの目開き（μｍ）を示す〕
に基づいて算出した。
(4) Average particle diameter 50 g of water-absorbing polymer particles were weighed, and eight standard sieves corresponding to JIS Z8801-1982 (in order from the top, sieves having openings of 850 μm, 500 μm, 355 μm, 300 μm, 250 μm, 180 μm, 106 μm) The water-absorbing polymer particles are put in the top sieve of the top and bottom containers stacked in order, and are shaken for 10 minutes using a low-tap sieve vibrator, and then weighed for each sieve. The particle diameter at which the cumulative mass is 50% based on the average particle diameter is calculated using the formula:
[Average particle diameter] = [(50−A) / (D−A)] × (C−B) + B
[In the formula, A is the cumulative value (g) when the cumulative value is obtained from the coarser particle size distribution, and the cumulative value at the point closest to 50% by mass is less than 50% by mass. , B is the opening (μm) when the integrated value is obtained, D is the integrated mass sequentially from the coarser particle size distribution, the integrated mass is 50% by mass or more, and the point closest to 50% by mass The integrated value (g) when the integrated value is obtained, and C indicates the opening (μm) when the integrated value is obtained.]
Calculated based on
（５）粒子破砕率
あらかじめ５００〜２５０μｍに分級した吸水性ポリマー粒子０．３０ｇを１０ｃｍ×１０ｃｍの薬包紙２枚の間に均一に広げ、この薬包紙の上に重さ５００ｇのローラーを５往復転がした後、薬包紙上の粒子を集め、目開きが２５０μｍの篩で再度ふるい、その篩上に残った粒子の重量Ｕ（ｇ）を計量し、式：
〔粒子破砕率（％）〕＝（１−Ｕ／０．３０）×１００
に基づいて粒子破砕率を算出した。
(5) Particle crushing rate 0.30 g of water-absorbing polymer particles classified in advance to 500 to 250 μm was spread evenly between two 10 cm × 10 cm medicine-wrapping paper, and a 500-gram roller was rolled back and forth on this medicine-wrapping paper 5 times. After that, the particles on the medicine wrapping paper are collected, sieved again with a sieve having an opening of 250 μm, the weight U (g) of the particles remaining on the sieve is weighed, and the formula:
[Particle crushing rate (%)] = (1−U / 0.30) × 100
Based on the above, the particle crushing rate was calculated.
（６）単量体水溶液の粘度
下記の手順にしたがって、単量体水溶液の粘度を測定した。
単量体水溶液約２００ｍＬを２００ｍＬ容トールビーカーに入れ、２５℃±０．５℃の恒温槽にて1時間以上放置することにより、その温度を２５℃±０．５℃の恒温にした。この単量体水溶液を、Ｂ型粘度計（ＢＭ型）にて、Ｎｏ．２のローターを用いて１２ｒｐｍの回転速度にて５回粘度を測定し、その平均値を単量体水溶液の粘度とした。
(6) Viscosity of aqueous monomer solution The viscosity of the aqueous monomer solution was measured according to the following procedure.
About 200 mL of the aqueous monomer solution was placed in a 200 mL tall beaker and allowed to stand in a thermostatic bath at 25 ° C. ± 0.5 ° C. for 1 hour or longer, thereby adjusting the temperature to 25 ° C. ± 0.5 ° C. This monomer aqueous solution was measured using a B-type viscometer (BM type). The viscosity was measured 5 times using a rotor No. 2 at a rotation speed of 12 rpm, and the average value was taken as the viscosity of the monomer aqueous solution.
表１および図１〜６に示された結果から、各実施例で得られた多孔質吸水性ポリマー粒子は、いずれも、多数の連続空孔を有することが観察された。このことから、得られた多孔質吸水性ポリマー粒子は、吸水速度が速くなる傾向があることがわかる。 From the results shown in Table 1 and FIGS. 1 to 6, it was observed that the porous water-absorbing polymer particles obtained in each example had a large number of continuous pores. This shows that the obtained porous water-absorbing polymer particles tend to have a high water absorption rate.
一方、比較例５に示された結果から、多孔質吸水性ポリマーであっても、嵩密度が０．３ｇ／ｍＬよりも小さい場合には、粒子破砕率が高くなることから、粒子の強度が低下する傾向があることがわかる。 On the other hand, from the results shown in Comparative Example 5, even in the case of a porous water-absorbing polymer, when the bulk density is less than 0.3 g / mL, the particle crushing rate is increased, so the strength of the particles is It can be seen that there is a tendency to decrease.
本発明の製造法によって得られた多孔質吸水性ポリマー粒子は、紙オムツ、生理用ナプキン、失禁パッド、ペットシートなどに好適に使用することができる。 The porous water-absorbing polymer particles obtained by the production method of the present invention can be suitably used for paper diapers, sanitary napkins, incontinence pads, pet sheets and the like.
Claims (10)
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| JP2005171420A JP4721780B2 (en) | 2005-06-10 | 2005-06-10 | Method for producing porous water-absorbing polymer particles |
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