CN118055969A - Superabsorbent polymer composition and method of making the same - Google Patents
Superabsorbent polymer composition and method of making the same Download PDFInfo
- Publication number
- CN118055969A CN118055969A CN202280067241.0A CN202280067241A CN118055969A CN 118055969 A CN118055969 A CN 118055969A CN 202280067241 A CN202280067241 A CN 202280067241A CN 118055969 A CN118055969 A CN 118055969A
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- Prior art keywords
- superabsorbent polymer
- polymer
- additive
- particles
- chemical formula
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- 229920000247 superabsorbent polymer Polymers 0.000 title claims abstract description 234
- 239000000203 mixture Substances 0.000 title claims abstract description 162
- 238000004519 manufacturing process Methods 0.000 title description 7
- 229920000642 polymer Polymers 0.000 claims abstract description 181
- 239000000654 additive Substances 0.000 claims abstract description 136
- 230000000996 additive effect Effects 0.000 claims abstract description 121
- 238000000034 method Methods 0.000 claims abstract description 115
- 239000002245 particle Substances 0.000 claims description 210
- 239000000126 substance Substances 0.000 claims description 115
- 239000000178 monomer Substances 0.000 claims description 85
- 238000001035 drying Methods 0.000 claims description 74
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 72
- 239000003431 cross linking reagent Substances 0.000 claims description 68
- 230000002378 acidificating effect Effects 0.000 claims description 44
- 150000001875 compounds Chemical class 0.000 claims description 44
- 229920005601 base polymer Polymers 0.000 claims description 43
- 238000004132 cross linking Methods 0.000 claims description 38
- 238000010521 absorption reaction Methods 0.000 claims description 33
- 230000003472 neutralizing effect Effects 0.000 claims description 30
- 239000003505 polymerization initiator Substances 0.000 claims description 24
- 239000003795 chemical substances by application Substances 0.000 claims description 22
- 125000004432 carbon atom Chemical group C* 0.000 claims description 20
- 229920006037 cross link polymer Polymers 0.000 claims description 17
- 239000001257 hydrogen Substances 0.000 claims description 14
- 229910052739 hydrogen Inorganic materials 0.000 claims description 14
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 claims description 13
- 125000003342 alkenyl group Chemical group 0.000 claims description 11
- 125000000217 alkyl group Chemical group 0.000 claims description 11
- 238000005520 cutting process Methods 0.000 claims description 11
- 238000012546 transfer Methods 0.000 claims description 9
- 125000004430 oxygen atom Chemical group O* 0.000 claims description 7
- 230000000379 polymerizing effect Effects 0.000 claims description 7
- 230000014759 maintenance of location Effects 0.000 claims description 4
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims description 3
- 239000011148 porous material Substances 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 2
- 238000004220 aggregation Methods 0.000 abstract description 37
- 230000002776 aggregation Effects 0.000 abstract description 36
- 230000002401 inhibitory effect Effects 0.000 abstract description 3
- 238000006116 polymerization reaction Methods 0.000 description 62
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- 230000008569 process Effects 0.000 description 45
- -1 i.e. Substances 0.000 description 41
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- 239000010419 fine particle Substances 0.000 description 26
- 239000003999 initiator Substances 0.000 description 22
- 239000000463 material Substances 0.000 description 21
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 19
- 238000006386 neutralization reaction Methods 0.000 description 19
- 239000000243 solution Substances 0.000 description 19
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 18
- 238000010438 heat treatment Methods 0.000 description 18
- 239000000047 product Substances 0.000 description 17
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 16
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 15
- 239000004583 superabsorbent polymers (SAPs) Substances 0.000 description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 14
- 230000000704 physical effect Effects 0.000 description 14
- 239000004094 surface-active agent Substances 0.000 description 13
- 239000007788 liquid Substances 0.000 description 12
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- 238000009826 distribution Methods 0.000 description 11
- 125000000524 functional group Chemical group 0.000 description 11
- 238000002360 preparation method Methods 0.000 description 11
- 239000003638 chemical reducing agent Substances 0.000 description 10
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- 239000002609 medium Substances 0.000 description 9
- 229910052757 nitrogen Inorganic materials 0.000 description 9
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 8
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 8
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- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
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- 229920001223 polyethylene glycol Polymers 0.000 description 6
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 5
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 5
- KWYHDKDOAIKMQN-UHFFFAOYSA-N N,N,N',N'-tetramethylethylenediamine Chemical compound CN(C)CCN(C)C KWYHDKDOAIKMQN-UHFFFAOYSA-N 0.000 description 5
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- 150000003839 salts Chemical class 0.000 description 5
- 239000011780 sodium chloride Substances 0.000 description 5
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- 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
- SVTBMSDMJJWYQN-UHFFFAOYSA-N 2-methylpentane-2,4-diol Chemical compound CC(O)CC(C)(C)O SVTBMSDMJJWYQN-UHFFFAOYSA-N 0.000 description 4
- 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 4
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 4
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 4
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- 239000002202 Polyethylene glycol Substances 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 235000010323 ascorbic acid Nutrition 0.000 description 4
- 239000011668 ascorbic acid Substances 0.000 description 4
- 229960005070 ascorbic acid Drugs 0.000 description 4
- 239000012267 brine Substances 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 4
- 239000002504 physiological saline solution Substances 0.000 description 4
- 239000011734 sodium Substances 0.000 description 4
- 235000011121 sodium hydroxide Nutrition 0.000 description 4
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 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 3
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- LCZVSXRMYJUNFX-UHFFFAOYSA-N 2-[2-(2-hydroxypropoxy)propoxy]propan-1-ol Chemical compound CC(O)COC(C)COC(C)CO LCZVSXRMYJUNFX-UHFFFAOYSA-N 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 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 3
- 239000003963 antioxidant agent Substances 0.000 description 3
- 230000003078 antioxidant effect Effects 0.000 description 3
- 235000006708 antioxidants Nutrition 0.000 description 3
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 3
- JLNSPUHKOIYHEZ-UHFFFAOYSA-L disodium 2-hydroxy-2-oxo-1-sulfinylethanolate Chemical compound C(=O)(C(=S=O)[O-])O.C(=O)(C(=S=O)[O-])O.[Na+].[Na+] JLNSPUHKOIYHEZ-UHFFFAOYSA-L 0.000 description 3
- 230000001747 exhibiting effect Effects 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 230000036571 hydration Effects 0.000 description 3
- 238000006703 hydration reaction Methods 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 3
- 229920001451 polypropylene glycol Polymers 0.000 description 3
- 239000011164 primary particle Substances 0.000 description 3
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 3
- 150000003254 radicals Chemical class 0.000 description 3
- XWGJFPHUCFXLBL-UHFFFAOYSA-M rongalite Chemical compound [Na+].OCS([O-])=O XWGJFPHUCFXLBL-UHFFFAOYSA-M 0.000 description 3
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
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- DNIAPMSPPWPWGF-VKHMYHEASA-N (+)-propylene glycol Chemical compound C[C@H](O)CO DNIAPMSPPWPWGF-VKHMYHEASA-N 0.000 description 2
- KOFLVDBWRHFSAB-UHFFFAOYSA-N 1,2,4,5-tetrahydro-1-(phenylmethyl)-5,9b(1',2')-benzeno-9bh-benz(g)indol-3(3ah)-one Chemical compound C1C(C=2C3=CC=CC=2)C2=CC=CC=C2C23C1C(=O)CN2CC1=CC=CC=C1 KOFLVDBWRHFSAB-UHFFFAOYSA-N 0.000 description 2
- 229940015975 1,2-hexanediol Drugs 0.000 description 2
- YPFDHNVEDLHUCE-UHFFFAOYSA-N 1,3-propanediol Substances OCCCO YPFDHNVEDLHUCE-UHFFFAOYSA-N 0.000 description 2
- 229940035437 1,3-propanediol Drugs 0.000 description 2
- XLLIQLLCWZCATF-UHFFFAOYSA-N 2-methoxyethyl acetate Chemical compound COCCOC(C)=O XLLIQLLCWZCATF-UHFFFAOYSA-N 0.000 description 2
- SPXWGAHNKXLXAP-UHFFFAOYSA-N 2-methylpentane-1,3-diol Chemical compound CCC(O)C(C)CO SPXWGAHNKXLXAP-UHFFFAOYSA-N 0.000 description 2
- QWGRWMMWNDWRQN-UHFFFAOYSA-N 2-methylpropane-1,3-diol Chemical compound OCC(C)CO QWGRWMMWNDWRQN-UHFFFAOYSA-N 0.000 description 2
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
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- 239000000908 ammonium hydroxide Substances 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
- CDQSJQSWAWPGKG-UHFFFAOYSA-N butane-1,1-diol Chemical compound CCCC(O)O CDQSJQSWAWPGKG-UHFFFAOYSA-N 0.000 description 2
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- BGTOWKSIORTVQH-UHFFFAOYSA-N cyclopentanone Chemical compound O=C1CCCC1 BGTOWKSIORTVQH-UHFFFAOYSA-N 0.000 description 2
- VFHVQBAGLAREND-UHFFFAOYSA-N diphenylphosphoryl-(2,4,6-trimethylphenyl)methanone Chemical compound CC1=CC(C)=CC(C)=C1C(=O)P(=O)(C=1C=CC=CC=1)C1=CC=CC=C1 VFHVQBAGLAREND-UHFFFAOYSA-N 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- FHKSXSQHXQEMOK-UHFFFAOYSA-N hexane-1,2-diol Chemical compound CCCCC(O)CO FHKSXSQHXQEMOK-UHFFFAOYSA-N 0.000 description 2
- AVIYEYCFMVPYST-UHFFFAOYSA-N hexane-1,3-diol Chemical compound CCCC(O)CCO AVIYEYCFMVPYST-UHFFFAOYSA-N 0.000 description 2
- XXMIOPMDWAUFGU-UHFFFAOYSA-N hexane-1,6-diol Chemical compound OCCCCCCO XXMIOPMDWAUFGU-UHFFFAOYSA-N 0.000 description 2
- OHMBHFSEKCCCBW-UHFFFAOYSA-N hexane-2,5-diol Chemical compound CC(O)CCC(C)O OHMBHFSEKCCCBW-UHFFFAOYSA-N 0.000 description 2
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- 230000003993 interaction Effects 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 239000000693 micelle Substances 0.000 description 2
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- 230000004048 modification Effects 0.000 description 2
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- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 2
- 239000002736 nonionic surfactant Substances 0.000 description 2
- 150000002918 oxazolines Chemical class 0.000 description 2
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- 229920000259 polyoxyethylene lauryl ether Polymers 0.000 description 2
- 229920000166 polytrimethylene carbonate Polymers 0.000 description 2
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
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- HRZFUMHJMZEROT-UHFFFAOYSA-L sodium disulfite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])(=O)=O HRZFUMHJMZEROT-UHFFFAOYSA-L 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
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- 239000002562 thickening agent Substances 0.000 description 2
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- MYWOJODOMFBVCB-UHFFFAOYSA-N 1,2,6-trimethylphenanthrene Chemical compound CC1=CC=C2C3=CC(C)=CC=C3C=CC2=C1C MYWOJODOMFBVCB-UHFFFAOYSA-N 0.000 description 1
- RRQYJINTUHWNHW-UHFFFAOYSA-N 1-ethoxy-2-(2-ethoxyethoxy)ethane Chemical compound CCOCCOCCOCC RRQYJINTUHWNHW-UHFFFAOYSA-N 0.000 description 1
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- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- FDSUVTROAWLVJA-UHFFFAOYSA-N 2-[[3-hydroxy-2,2-bis(hydroxymethyl)propoxy]methyl]-2-(hydroxymethyl)propane-1,3-diol;prop-2-enoic acid Chemical compound OC(=O)C=C.OC(=O)C=C.OC(=O)C=C.OC(=O)C=C.OC(=O)C=C.OCC(CO)(CO)COCC(CO)(CO)CO FDSUVTROAWLVJA-UHFFFAOYSA-N 0.000 description 1
- POAOYUHQDCAZBD-UHFFFAOYSA-N 2-butoxyethanol Chemical compound CCCCOCCO POAOYUHQDCAZBD-UHFFFAOYSA-N 0.000 description 1
- CKSAKVMRQYOFBC-UHFFFAOYSA-N 2-cyanopropan-2-yliminourea Chemical compound N#CC(C)(C)N=NC(N)=O CKSAKVMRQYOFBC-UHFFFAOYSA-N 0.000 description 1
- 125000006040 2-hexenyl group Chemical group 0.000 description 1
- 125000000954 2-hydroxyethyl group Chemical group [H]C([*])([H])C([H])([H])O[H] 0.000 description 1
- QENRKQYUEGJNNZ-UHFFFAOYSA-N 2-methyl-1-(prop-2-enoylamino)propane-1-sulfonic acid Chemical compound CC(C)C(S(O)(=O)=O)NC(=O)C=C QENRKQYUEGJNNZ-UHFFFAOYSA-N 0.000 description 1
- 125000003229 2-methylhexyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- SMBRHGJEDJVDOB-UHFFFAOYSA-N 2-methylpropanimidamide;dihydrochloride Chemical compound Cl.Cl.CC(C)C(N)=N SMBRHGJEDJVDOB-UHFFFAOYSA-N 0.000 description 1
- BPAZNZINLQSFMN-UHFFFAOYSA-N 2-propan-2-yl-4,5-dihydro-1h-imidazole;dihydrochloride Chemical compound Cl.Cl.CC(C)C1=NCCN1 BPAZNZINLQSFMN-UHFFFAOYSA-N 0.000 description 1
- MJIFFWRTVONWNO-UHFFFAOYSA-N 3-oxopent-4-ene-1-sulfonic acid Chemical compound OS(=O)(=O)CCC(=O)C=C MJIFFWRTVONWNO-UHFFFAOYSA-N 0.000 description 1
- JFMGYULNQJPJCY-UHFFFAOYSA-N 4-(hydroxymethyl)-1,3-dioxolan-2-one Chemical compound OCC1COC(=O)O1 JFMGYULNQJPJCY-UHFFFAOYSA-N 0.000 description 1
- SVYPQURSUBDSIQ-UHFFFAOYSA-N 4-methyl-3-oxopent-4-ene-1-sulfonic acid Chemical compound CC(=C)C(=O)CCS(O)(=O)=O SVYPQURSUBDSIQ-UHFFFAOYSA-N 0.000 description 1
- AEYSASDBPHWTGR-UHFFFAOYSA-N 4-oxohex-5-ene-3-sulfonic acid Chemical compound CCC(S(O)(=O)=O)C(=O)C=C AEYSASDBPHWTGR-UHFFFAOYSA-N 0.000 description 1
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- ZMDDERVSCYEKPQ-UHFFFAOYSA-N Ethyl (mesitylcarbonyl)phenylphosphinate Chemical compound C=1C=CC=CC=1P(=O)(OCC)C(=O)C1=C(C)C=C(C)C=C1C ZMDDERVSCYEKPQ-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
Superabsorbent polymer compositions and methods of making the same are provided. More specifically, a method of preparing a superabsorbent polymer composition is provided that is capable of inhibiting aggregation of an aqueous gel polymer and improving crushing processability during crushing by including an additive having a specific structure.
Description
Technical Field
Cross Reference to Related Applications
The present application is based on and claims priority from korean patent application nos. 10-2021-0147025 and 10-2022-0140642, filed on 10-month 29 of 2021 and 27 of 2022, respectively, the disclosures of which are incorporated herein by reference in their entireties.
The present invention relates to superabsorbent polymer compositions and methods of making the same. More particularly, the present invention relates to a method for preparing a superabsorbent polymer composition capable of inhibiting aggregation of an aqueous gel polymer and improving crushing processability during crushing by containing an additive having a specific structure.
Background
Superabsorbent polymers (superabsorbent polymer, SAP) are synthetic polymeric materials capable of absorbing 500 to 1000 times their own weight of moisture. Different manufacturers name them different names, such as SAM (Super Absorbency Material, superabsorbent material), AGM (Absorbent GEL MATERIAL ), etc. Since such super absorbent polymers have been practically used for sanitary products, they have been widely used for water-retaining soil products for gardening, water-stopping materials for civil engineering and construction, sheets for raising seedlings, antistatics for food circulation, materials for cataplasm, and the like.
These superabsorbent polymers are widely used in sanitary materials, such as diapers, sanitary napkins and the like. Inside the sanitary material, the superabsorbent polymer is typically distributed throughout the pulp. However, efforts have been made recently to provide sanitary materials such as diapers having a thinner thickness, and as part of the efforts, diapers having a reduced content of pulp, and also diapers having no pulp (so-called pulpless diapers), are being actively developed.
Such sanitary materials with reduced or no pulp contain superabsorbent polymers in a relatively high ratio, and superabsorbent polymer particles are inevitably contained as multiple layers in the sanitary material. In order for all of the superabsorbent polymer particles contained as layers to more effectively absorb a large amount of liquid such as urine or the like, the superabsorbent polymer is basically required to exhibit high absorption performance and a fast absorption rate.
On the other hand, such superabsorbent polymers are generally prepared by the steps of: a step of preparing an aqueous gel polymer containing a large amount of water by polymerizing the monomers, and a step of coarsely pulverizing and drying the aqueous gel polymer and then pulverizing the aqueous gel polymer into polymer particles having a desired particle size. In particular, during the course of coarsely pulverizing the aqueous gel polymer, there is a problem in that the coarsely pulverized aqueous gel polymer is agglomerated or aggregated with each other and thus pulverization thereof does not easily occur.
Accordingly, there is a continuing need to develop techniques and methods that can improve the absorption rate of superabsorbent polymers to develop such techniques: it can improve the pulverizing processability in addition to improving the water holding capacity (water retention capacity, CRC), which is a physical property indicating the basic absorbency and water holding capacity of the super absorbent polymer, and the absorbency under pressure (absorbency under pressure, AUP), which indicates a property of well retaining the absorbed liquid even under external pressure.
Disclosure of Invention
Technical problem
Accordingly, a method of preparing a superabsorbent polymer composition is provided that is capable of inhibiting aggregation of an aqueous gel polymer and improving comminution processability during comminution by including an additive having a specific structure.
Technical proposal
In order to achieve the above object, there is provided a superabsorbent polymer composition comprising:
Superabsorbent polymer particles comprising a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having an acidic group and an internal crosslinking agent; and
An additive represented by the following chemical formula 1:
[ chemical formula 1]
In the chemical formula 1, the chemical formula is shown in the drawing,
A 1、A2 and A 3 are each independently a single bond, carbonyl group, Provided that one or more of A 1、A2 and A 3 is carbonyl orWherein m1, m2 and m3 are each independently integers from 1 to 8,Is linked to an adjacent oxygen atom, respectively to adjacent R 1、R2 and R 3,
R 1、R2 and R 3 are each independently hydrogen, a linear or branched alkyl group having 6 to 18 carbon atoms, or a linear or branched alkenyl group having 6 to 18 carbon atoms, and
N is an integer from 1 to 9.
Furthermore, a method of preparing a superabsorbent polymer composition is provided, the method comprising the steps of:
forming a polymer by cross-linking polymerizing a water-soluble ethylenically unsaturated monomer having an acidic group in the presence of an internal cross-linking agent and a polymerization initiator (step 1);
Neutralizing at least part of the acidic groups of the polymer (step 2);
Preparing base polymer particles by micronizing a polymer in the presence of an additive represented by the following chemical formula 1 (step 3); and
Drying the base polymer particles (step 4):
[ chemical formula 1]
In the chemical formula 1, the chemical formula is shown in the drawing,
A 1、A2 and A 3 are each independently a single bond, carbonyl group, Provided that one or more of A 1、A2 and A 3 is carbonyl orWherein m1, m2 and m3 are each independently integers from 1 to 8,Is linked to an adjacent oxygen atom, respectively to adjacent R 1、R2 and R 3,
R 1、R2 and R 3 are each independently hydrogen, a linear or branched alkyl group having 6 to 18 carbon atoms, or a linear or branched alkenyl group having 6 to 18 carbon atoms, and
N is an integer from 1 to 9.
Advantageous effects
According to the superabsorbent polymer composition and the method of preparing the same of the present invention, an additive having a specific structure is injected during the process of pulverizing an aqueous gel polymer to inhibit aggregation of aqueous gel polymer particles, thereby improving pulverization processability, and thus, absorption performance and absorption rate of the superabsorbent polymer can be improved.
Drawings
FIG. 1 shows a flow chart showing a conventional method of preparing superabsorbent polymers; and
Fig. 2 shows a photograph showing an example of evaluation criteria in evaluating the aggregation characteristics of particles.
Detailed Description
The terminology used in the description presented herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless the context indicates otherwise, singular references may include plural references. It must be understood that the terms "comprises" and "comprising," "including," or "having," when used in this specification, are taken to specify the presence of stated features, steps, components, or groups thereof, but do not preclude the presence or addition of one or more different features, steps, components, or groups thereof.
While the invention is susceptible to various modifications and alternative forms, specific exemplary embodiments are shown and described in detail in the following description. However, the invention is not intended to be limited to the specific exemplary embodiments, and it must be understood that the invention includes every modification, equivalent or alternative included within the spirit and technical scope of the invention.
Hereinafter, a method of preparing a superabsorbent polymer and a superabsorbent polymer according to specific embodiments of the present invention will be described in more detail.
Before this time, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Furthermore, as used herein, singular references may include plural references unless the context is otherwise indicated.
As used herein, the term "polymer" refers to those that are in the polymerized state of water-soluble ethylenically unsaturated monomers, and may include all ranges of water content or ranges of particle sizes. Among the above polymers, a polymer having a water content (water content) of about 40% by weight or more before drying after polymerization may be referred to as an aqueous gel polymer, and particles obtained by pulverizing and drying such an aqueous gel polymer may be referred to as a crosslinked polymer.
Furthermore, the term "superabsorbent polymer particles" refers to materials in particulate form comprising crosslinked polymers obtained by polymerizing water-soluble ethylenically unsaturated monomers comprising at least partially neutralized acidic groups and crosslinking them by an internal crosslinking agent.
Furthermore, depending on the context, the term "superabsorbent polymer" refers to a crosslinked polymer obtained by polymerizing a water-soluble ethylenically unsaturated monomer containing at least partially neutralized acidic groups, or a base polymer in the form of a powder composed of superabsorbent polymer particles obtained by pulverizing the crosslinked polymer, or is intended to cover those which are made suitable for commercialization by subjecting the crosslinked polymer or the base polymer to another process such as surface crosslinking, reassembly of fine particles, drying, pulverizing, classifying, or the like. Thus, the term "superabsorbent polymer composition" may be interpreted as a composition comprising superabsorbent polymer, i.e. a plurality of superabsorbent polymer particles.
Furthermore, the term "fine particles" refers to particles in the superabsorbent polymer particles having a particle size of less than 150 μm. The particle size of the polymer particles can be measured according to the European disposables and nonwovens Association (European Disposables and Nonwovens Association, EDANA) standard WSP 220.3 method.
In addition, the term "shredding" refers to breaking the aqueous gel polymer into small pieces of millimeter size to increase drying efficiency, and is distinguished from particle sizes that are crushed to the micrometer or normal particle level.
Furthermore, the term "micronization (micronizing/micronization)" refers to comminuting aqueous gel polymers to a particle size of tens to hundreds of microns, and is distinguished from "shredding".
Meanwhile, superabsorbent polymers have traditionally been prepared by: the aqueous gel polymer thus formed is dried by cross-linking polymerization of a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups in the presence of an internal cross-linking agent and a polymerization initiator, and then the aqueous gel polymer is crushed to a desired particle size. At this time, in order to promote the drying of the aqueous gel polymer and to improve the efficiency of the pulverization process, a pulverization process is generally performed prior to the drying process, in which the aqueous gel polymer is pulverized into particles of a size of several millimeters. However, during this shredding process, the aqueous gel polymer cannot be broken into micron-sized particles due to the viscosity of the aqueous gel polymer, but becomes an aggregated gel. When such aggregated gel-type aqueous gel polymer is dried, a sheet-like dry product is formed, and in order to pulverize the sheet-like dry product into micrometer-sized particles, a multi-stage pulverizing process should be performed. In this process, there is a problem in that many fine particles are generated.
Specifically, a flow chart showing a conventional method of preparing superabsorbent polymers is shown in FIG. 1. Referring to fig. 1, a superabsorbent polymer is conventionally prepared by:
(neutralization) of at least part of the acidic groups of the water-soluble ethylenically unsaturated monomer;
(polymerization) a step of forming an aqueous gel polymer by crosslinking polymerization of a water-soluble ethylenically unsaturated monomer having an acid group which is at least partially neutralized in the presence of an internal crosslinking agent and a polymerization initiator;
(shredding) the aqueous gel polymer;
(drying) a step of drying the minced aqueous gel polymer; and
(Pulverization/classification) the dried polymer is pulverized and then classified into normal particles and fine particles.
As described above, the minced aqueous gel polymer has an aggregated gel shape having a size of about 1cm to about 10cm, and the minced aqueous gel polymer is stacked on a belt whose bottom is composed of a porous plate, and dried by hot air supplied from the lower or upper portion. Since the polymer dried by the drying method takes a sheet shape instead of a pellet shape, the step of classifying after pulverizing is performed by the steps of: the prepared particles were coarsely pulverized into normal particles, i.e., particles having a particle size of 150 μm to 850 μm, and then classified, followed by fine pulverization and classification. Since the amount of fine particles separated in the final classification step by such a production method is up to about 10% by weight to about 20% by weight relative to the total weight of the finally produced superabsorbent polymer, the separated fine particles are reused in such a manner: it is mixed with an appropriate amount of water to reassemble the fine particles, which are then injected into the shredding step or step prior to drying.
However, when the fine particle-reassembled body mixed with water for reuse of the fine particles is re-injected into the pulverizing or drying process, there is a problem in that: causing an increase in equipment load and/or energy consumption, and the unfractionated fine particles cause deterioration in physical properties of the superabsorbent polymer.
Accordingly, the present inventors determined that the amount of fine particles generated in the conventional production method seriously affects the pulverization process, and they found that when fine particles are produced in the form of aggregates of particles by adding a surfactant in the process of pulverizing fine particles (micronization process) to pulverize the fine particles more finely than before and simultaneously controlling aggregation, the amount of fine particles generated during the production process can be significantly reduced.
Meanwhile, when a surfactant is added to the neutralized aqueous gel polymer, the surfactant permeates into the aqueous gel polymer due to the high water content of the neutralized aqueous gel polymer, not being present at the interface of the aqueous gel polymer, and thus the surfactant cannot properly perform its function.
Many studies have been made to solve the problem, and as a result, it has been found that unlike in a conventional method for producing a superabsorbent polymer in which polymerization is carried out in a state in which an acid group of a water-soluble ethylenically unsaturated monomer is neutralized, when a polymer is obtained by carrying out polymerization in a state in which an acid group is not neutralized, an aqueous gel polymer is micronized in the presence of a surfactant, and then the acid group of the polymer is neutralized, or when an aqueous gel polymer is formed by neutralizing the acid group of the polymer, and then the aqueous gel polymer is micronized in the presence of a surfactant, or when micronization is carried out and at the same time the acid group present in the polymer is neutralized, a large amount of surfactant is present on the surface of the polymer to thereby reduce the high tackiness of the polymer, thereby sufficiently exerting its effect of preventing excessive aggregation of the polymer and controlling the aggregation state at a desired level.
Accordingly, the polymer is prepared as secondary particles in which primary particles are aggregated, and then the pulverizing and drying process is performed under milder conditions, and thus, the amount of fine particles generated during the process can be significantly reduced.
Further, when the polymer is pulverized in the presence of the additive having a specific structure of chemical formula 1 as described above, the hydrophobic functional moiety contained in the additive imparts hydrophobicity to the surface of the pulverized superabsorbent polymer particles, thereby reducing frictional force between the particles. Thus, while increasing the bulk density of the superabsorbent polymer, the hydrophilic functional moieties contained in the additive are also bound to the superabsorbent polymer particles, so that the surface tension of the polymer is not reduced. Therefore, the superabsorbent polymer prepared according to the above-described preparation method can have a high bulk density value while exhibiting a surface tension comparable to that of a polymer prepared without using such additives.
Further, when a polymer is formed by conducting polymerization in an unneutralized state, and then acidic groups present in the polymer are neutralized, it is possible to form a longer chain polymer and achieve the effect of reducing the content of a water-soluble component present in an uncrosslinked state due to incomplete crosslinking.
The water-soluble component has a property of easily flowing out when the superabsorbent polymer is contacted with a liquid, and therefore, when the content of the water-soluble component is high, most of the water-soluble component flowing out remains on the surface of the superabsorbent polymer and causes the superabsorbent polymer to become tacky, thereby causing a decrease in liquid permeability. Therefore, it is important to keep the content of the water-soluble component low in terms of liquid permeability.
In summary, the present inventors have determined that, when a polymer is pulverized by mixing with an additive having a specific structure represented by the following chemical formula 1, aggregation of pulverized aqueous gel polymer particles is suppressed to improve pulverization processability, leading to completion of the present invention. In particular, the particles contained in the superabsorbent polymer composition prepared according to the above preparation method are characterized by exhibiting an improved absorption rate compared to the case where the additive is not used.
[ Chemical formula 1]
In the chemical formula 1, the chemical formula is shown in the drawing,
A 1、A2 and A 3 are each independently a single bond, carbonyl group, Provided that one or more of A 1、A2 and A 3 is carbonyl orWherein m1, m2 and m3 are each independently integers from 1 to 8,Is linked to an adjacent oxygen atom, respectively to adjacent R 1、R2 and R 3,
R 1、R2 and R 3 are each independently hydrogen, a linear or branched alkyl group having 6 to 18 carbon atoms, or a linear or branched alkenyl group having 6 to 18 carbon atoms, and
N is an integer from 1 to 9.
Specifically, the additive represented by the following chemical formula 1 has both hydrophobic functional groups and hydrophilic functional groups. On the other hand, since the water-soluble ethylenically unsaturated monomer contains an acidic group (-COOH) and/or a neutralized acidic group (-COO-), a large amount of hydrophilic moieties of the acidic group (-COOH) and/or the acidic group (-COO-) which are not involved in the polymerization remain on the surface of the polymer produced by the polymerization. Thus, when the additive is mixed with a polymer, the hydrophilic functional group of the additive is adsorbed on at least a part of the hydrophilic portion present on the surface of the polymer, and the surface of the polymer on which the additive is adsorbed exhibits a hydrophobic property by the hydrophobic functional group at the other end of the additive. Thus, aggregation between the pulverized aqueous gel polymer particles can be suppressed.
Hereinafter, the components of the superabsorbent polymer composition of one embodiment will be described in more detail.
(Superabsorbent Polymer composition)
According to one embodiment of the present invention, there is provided a superabsorbent polymer composition comprising:
superabsorbent polymer particles comprising a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having an acidic group and an internal crosslinking agent; and an additive represented by the following chemical formula 1:
[ chemical formula 1]
In the chemical formula 1, the chemical formula is shown in the drawing,
Provided that one or more of A 1、A2 and A 3 is carbonyl orWherein m1, m2 and m3 are each independently integers from 1 to 8,Is linked to an adjacent oxygen atom, respectively to adjacent R 1、R2 and R 3,
R 1、R2 and R 3 are each independently hydrogen, a linear or branched alkyl group having 6 to 18 carbon atoms, or a linear or branched alkenyl group having 6 to 18 carbon atoms, and
N is an integer from 1 to 9.
The superabsorbent polymer composition of one embodiment comprises superabsorbent polymer particles comprising a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having an acidic group and an internal crosslinking agent. In this regard, the crosslinked polymer is obtained by crosslinking polymerization of a water-soluble ethylenically unsaturated monomer having an acidic group in the presence of an internal crosslinking agent, and has a three-dimensional network structure in which a main chain formed by polymerization of the monomer is crosslinked by the internal crosslinking agent.
In other words, the superabsorbent polymer composition of one embodiment comprises superabsorbent polymer particles comprising a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having an acidic group and an internal crosslinking agent. As described, when the crosslinked polymer has a three-dimensional network structure in which a main chain formed by polymerization of monomers is crosslinked by an internal crosslinking agent, the water holding capacity and absorption under pressure, which are the overall physical properties of the superabsorbent polymer, can be significantly improved as compared with a superabsorbent polymer having a two-dimensional linear structure in which additional crosslinking by an internal crosslinking agent is not performed.
The water-soluble ethylenically unsaturated monomer may be any monomer commonly used in the preparation of superabsorbent polymers. For non-limiting example, the water-soluble ethylenically unsaturated monomer may be a compound represented by the following chemical formula 2:
[ chemical formula 2]
R-COOM’
In the chemical formula 2, the chemical formula is shown in the drawing,
R is a C2-5 hydrocarbon group containing an unsaturated bond, and
M' is a hydrogen atom, a monovalent or divalent metal, an ammonium group or an organic amine salt.
Preferably, the monomer may be one or more selected from (meth) acrylic acid and monovalent (alkali) metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof.
When (meth) acrylic acid and/or a salt thereof is used as the water-soluble ethylenically unsaturated monomer, it is advantageous that a superabsorbent polymer having improved absorption characteristics can be obtained. Further, as the monomer, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2-methacryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, or 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamide, N-substituted (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, (N, N) -dimethylaminoethyl (meth) acrylate, (N, N) -dimethylaminopropyl (meth) acrylamide, and the like can be used.
Here, the water-soluble ethylenically unsaturated monomer has an acidic group, at least a part of which is neutralized with a neutralizing agent in a neutralization step described later. In this regard, as the neutralizing agent, a basic substance capable of neutralizing an acidic group, such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, or the like, which will be described in more detail in a preparation method described later, may be used.
Further, as used herein, the term "internal crosslinking agent" is a term for distinguishing it from a surface crosslinking agent for crosslinking the surface of the superabsorbent polymer particles described later, and the internal crosslinking agent is used to polymerize the water-soluble ethylenically unsaturated monomer by crosslinking the unsaturated bond of the water-soluble ethylenically unsaturated monomer. The crosslinking in the above step occurs both on the surface and inside the polymer. However, by the surface crosslinking process of the superabsorbent polymer particles described later, the particle surface of the finally produced superabsorbent polymer has a structure crosslinked by a surface crosslinking agent, and its interior has a structure crosslinked by an internal crosslinking agent.
As the internal crosslinking agent, any compound may be used as long as it enables the introduction of a crosslinking bond during the polymerization of the water-soluble ethylenically unsaturated monomer. For non-limiting examples, as internal crosslinking agents, the following alone or in combination of two or more of the following may be used: polyfunctional crosslinking agents such as N, N' -methylenebisacrylamide, trimethylol propane tri (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol (meth) acrylate, butane diol di (meth) acrylate, butanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipentaerythritol pentaacrylate, glycerol tri (meth) acrylate, pentaerythritol tetraacrylate, triarylamine, pentaerythritol triallyl ether, ethylene glycol diglycidyl ether, propylene glycol, glycerol, or ethylene carbonate, but are not limited thereto. Among them, pentaerythritol triallyl ether can be preferably used.
The crosslinking polymerization of the water-soluble ethylenically unsaturated monomer in the presence of the internal crosslinking agent may be carried out by thermal polymerization, photopolymerization or hybrid polymerization in the presence of a polymerization initiator, a thickener (if necessary), a plasticizer, a storage stabilizer, an antioxidant, or the like.
Such superabsorbent polymer particles may have a particle size of from about 150 μm to about 850 μm and the particle size may be measured according to the European Disposable and nonwoven Association (EDANA) standard WSP 220.3 method.
Further, the superabsorbent polymer composition includes an additive represented by chemical formula 1. As described above, the additive is mixed with the polymer, and added so that the micronization (chopping) step can be easily accomplished without aggregation.
The additive represented by chemical formula 1 is a nonionic surfactant and has excellent surface adsorption property by hydrogen bonding force even in the case of an unneutralized polymer, and thus, it is suitable for achieving a desired aggregation control effect. In contrast, when a nonionic surfactant is not mixed with a polymer neutralized with a neutralizing agent such as NaOH or Na 2SO4, it is adsorbed on the carboxyl substituent of the polymer via ionized Na + ions, and when mixed with a polymer not neutralized, there is a problem in that the adsorption efficiency to the polymer is relatively lowered due to competition with the anion of the carboxyl substituent of the polymer.
Specifically, in the additive represented by chemical formula 1, the hydrophobic functional group is a terminal functional group R 1、R2、R3 moiety (if not hydrogen), and the hydrophilic functional group further includes a glycerol-derived moiety and a terminal hydroxyl group in the chain (n=1 to 3 when a n is a single bond and at the same time when R n is hydrogen), wherein the glycerol-derived moiety and the terminal hydroxyl group are hydrophilic functional groups and are used to improve adsorption performance on the polymer surface. Thus, aggregation of the superabsorbent polymer particles can be effectively suppressed.
In chemical formula 1, the hydrophobic functional groups R 1、R2、R3 moieties (if not hydrogen) are each independently a linear or branched alkyl group having 6 to 18 carbon atoms, or a linear or branched alkenyl group having 6 to 18 carbon atoms. In this regard, when the R 1、R2 and R 3 moieties (if not hydrogen) are alkyl or alkenyl groups having less than 6 carbon atoms, there is a problem in that the aggregation of the crushed particles may not be effectively controlled due to the chain length. When the R 1、R2 and R 3 moieties (if not hydrogen) are alkyl or alkenyl groups having more than 18 carbon atoms, there may be problems: the additive may not be effectively mixed with the polymer because of its reduced flowability and the increased unit price of the composition due to the increased cost of the additive.
Preferably, when R 1、R2 and R 3 may be hydrogen or straight or branched chain alkyl having 6 to 18 carbon atoms, they may be 2-methylhexyl, n-heptyl, 2-methylheptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl or n-octadecyl, or when R 1、R2 and R 3 may be straight or branched chain alkenyl having 6 to 18 carbon atoms, they may be 2-hexenyl, 2-heptenyl, 2-octenyl, 2-nonenyl, n-decenyl, 2-undecenyl, 2-dodecenyl, 2-tridecenyl, 2-tetradecenyl, 2-pentadecenyl, 2-hexadecenyl, 2-heptadecenyl or 2-octadecenyl.
The additive may be selected from compounds represented by the following chemical formulas 1-1 to 1-14:
[ chemical formula 1-1]
[ Chemical formulas 1-2]
[ Chemical formulas 1-3]
[ Chemical formulas 1-4]
[ Chemical formulas 1-5]
[ Chemical formulas 1-6]
[ Chemical formulas 1-7]
[ Chemical formulas 1-8]
[ Chemical formulas 1-9]
[ Chemical formulas 1-10]
[ Chemical formulas 1-11]
[ Chemical formulas 1-12]
[ Chemical formulas 1-13]
[ Chemical formulas 1-14]
The additive may be contained in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of the water-soluble ethylenically unsaturated monomer. When the total content of the additive with respect to the monomers in the composition is too low, the effect of controlling aggregation by the additive is small, and thus superabsorbent polymer particles that are not pulverized to a desired particle size may be contained. When the total content of the additives is too high, the balance of the water holding capacity and the absorbency under pressure, which are the overall physical properties of the super absorbent polymer, may be deteriorated.
The content of said additive in the superabsorbent polymer composition can be measured by: 1g of the super absorbent polymer composition was added to 1ml of distilled water, thoroughly mixed for 1 hour until swelling, and only a solution portion was extracted by filtration, and then the content of the additive dissolved in the solution portion was analyzed by performing HPLC analysis.
More specifically, the additive may be contained in the following amounts relative to 100 parts by weight of the water-soluble ethylenically unsaturated monomer: 0.01 part by weight or more, 0.02 part by weight or more, 0.05 part by weight or more, 0.1 part by weight or more, or 0.5 part by weight or more, and 10 parts by weight or less, 8 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, or 2 parts by weight or less.
At the same time, at least part of the additive may be present on the surface of the superabsorbent polymer particles. Herein, "at least part of the additive is present on the surface of the superabsorbent polymer particles" means that at least part of the additive is adsorbed or bound on the surface of the superabsorbent polymer particles. In particular, the additive may be physically or chemically adsorbed on the surface of the superabsorbent polymer. More specifically, the hydrophilic functional groups of the additive may be physically adsorbed on the hydrophilic portions of the surface of the superabsorbent polymer by intermolecular forces such as dipole-dipole interactions. As described, the hydrophilic portion of the additive is physically adsorbed on the surface of the superabsorbent polymer particles to cover the surface, and the hydrophobic portion of the additive is not adsorbed on the surface of the polymer particles, and thus the surface of the polymer particles may be coated with the additive in a micelle structure.
Therefore, when at least a part of the additive is present on the surface of the superabsorbent polymer particles, the aggregation phenomenon in which the pulverized particles aggregate with each other during the process of preparing the superabsorbent polymer composition can be more effectively suppressed than in the case where the entire additive of chemical formula 1 is present inside the superabsorbent polymer particles (specifically, inside the crosslinked polymer).
Furthermore, because at least a portion of the additive is present on the surface of the superabsorbent polymer particles, superabsorbent polymer compositions comprising the additive may have an improved absorption rate compared to compositions without the additive.
Meanwhile, when the superabsorbent polymer composition does not further include a surface cross-linking layer described later, it may contain no other hydrophilic additive except for a plurality of superabsorbent polymer particles, the additive, and an additive hydrolysate generated by hydrolysis of the additive during a process of preparing the superabsorbent polymer.
In particular, the superabsorbent polymer composition of an embodiment may be free of compounds having a plurality of hydroxyl-containing glucose units in the molecule, such as microcrystalline cellulose. For example, when the superabsorbent polymer composition comprises microcrystalline cellulose having an average particle size of 1 μm to 10 μm, such as is obtainable from FMC, represented by the following chemical formula 3At PH-101, aggregation between superabsorbent polymer particles may not be inhibited due to the plurality of hydroxyl groups, and thus the above-described effects of the additive may not be effectively exhibited.
[ Chemical formula 3]
Furthermore, the superabsorbent polymer composition of an embodiment may be free of hydrophilic additives such as: polyethylene glycol, polypropylene glycol, poly (ethylene glycol) -poly (propylene glycol) copolymer, polyoxyethylene lauryl ether carboxylic acid, sodium polyoxyethylene lauryl ether carboxylate, lauryl sulfate, sodium lauryl sulfate, and the like. Since such additives cannot be sufficiently adsorbed on the surface of the crosslinked polymer, there is a problem in that aggregation between the superabsorbent polymer particles cannot be effectively suppressed. Therefore, when the superabsorbent polymer composition contains the hydrophilic additive as described above instead of the additive of chemical formula 1, aggregation between particles is not inhibited after pulverization of the crosslinked polymer, and thus the superabsorbent polymer composition contains a large number of fine particles and exhibits low water retention capacity and low bulk density.
Meanwhile, the superabsorbent polymer composition may further comprise a surface cross-linked layer formed on at least part of the surface of the superabsorbent polymer particles by further cross-linking the cross-linked polymer via a surface cross-linking agent. This is to increase the surface cross-linking density of the superabsorbent polymer particles. When the superabsorbent polymer particles further comprise a surface cross-linked layer as described above, they may have a structure in which the cross-link density of the outer portion is higher than that of the inner portion.
As the surface cross-linking agent, any surface cross-linking agent conventionally used for producing superabsorbent polymers can be used without any particular limitation. For example, the surface cross-linking agent may include: one or more polyhydric alcohols selected from the group consisting of ethylene glycol, propylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, 1, 2-hexanediol, 1, 3-hexanediol, 2-methyl-1, 3-propanediol, 2, 5-hexanediol, 2-methyl-1, 3-pentanediol, 2-methyl-2, 4-pentanediol, tripropylene glycol, and glycerin; one or more carbonate-based compounds selected from ethylene carbonate, propylene carbonate and glycerol carbonate; epoxy compounds such as ethylene glycol diglycidyl ether; oxazoline compounds, e.g./> Oxazolidinones and the like; a polyamine compound; /(I)An oxazoline compound; singleOxazolidinone, diOxazolidinone or polyAn oxazolidinone compound; a cyclic urea compound; etc.
Specifically, as the surface cross-linking agent, one or more, two or more, or three or more of the foregoing surface cross-linking agents may be used. For example, propylene glycol, ethylene carbonate, propylene carbonate may be used.
Further, the superabsorbent polymer composition may have an absorption rate (vortex time) of 30 seconds or less, 27 seconds or less, 25 seconds or less, 20 seconds or less, 15 seconds or less, or 12 seconds or less, as measured according to the vortex method at 24.0 ℃. Further, as the value of the absorption rate is smaller, it is more excellent, and thus the lower limit of the absorption rate is theoretically 0 seconds. For example, it may be about 5 seconds or more, or about 8 seconds or more, or about 10 seconds or more. In this regard, a method of measuring the absorption rate of the superabsorbent polymer will be described in more detail in experimental examples described later.
Furthermore, the water retention capacity (CRC) of the superabsorbent polymer composition may be in the range of 39g/g or more or 40g/g or more, or 50g/g or less, or 48g/g or less, or 45g/g or less, as measured according to EDANA method WSP 241.3. The method of measuring the water holding capacity will be described in more detail in experimental examples described later.
Further, the superabsorbent polymer composition may have an Absorbency Under Pressure (AUP) of 24.0g/g or greater, 25.0g/g or greater, 26.0g/g or greater, or 24.3g/g or greater, and 30g/g or less, 28.0g/g or less, or 26.0g/g or less, as measured according to EDANA method WSP 242.3. The method of measuring the absorption under pressure will be described in more detail in experimental examples described later.
(Method of preparing superabsorbent Polymer composition)
Meanwhile, the superabsorbent polymer composition may be prepared by comprising the steps of:
forming a polymer by cross-linking polymerizing a water-soluble ethylenically unsaturated monomer having an acidic group in the presence of an internal cross-linking agent and a polymerization initiator (step 1);
Neutralizing at least part of the acidic groups of the polymer (step 2);
Preparing base polymer particles by micronizing a polymer in the presence of an additive represented by the following chemical formula 1 (step 3); and
Drying the base polymer particles (step 4):
[ chemical formula 1]
In the chemical formula 1, the chemical formula is shown in the drawing,
A 1、A2 and A 3 are each independently a single bond, carbonyl group, Provided that one or more of A 1、A2 and A 3 is carbonyl orWherein m1, m2 and m3 are each independently integers from 1 to 8,Is linked to an adjacent oxygen atom, respectively to adjacent R 1、R2 and R 3,
R 1、R2 and R 3 are each independently hydrogen, a linear or branched alkyl group having 6 to 18 carbon atoms, or a linear or branched alkenyl group having 6 to 18 carbon atoms, and
N is an integer from 1 to 9.
Hereinafter, each step of the method of preparing a superabsorbent polymer of one embodiment will be described in more detail.
(Step 1)
In the method of producing a superabsorbent polymer according to one embodiment, a step of forming an aqueous gel polymer by cross-linking polymerizing a water-soluble ethylenically unsaturated monomer having an acidic group in the presence of an internal cross-linking agent and a polymerization initiator is first performed.
This step may consist of the steps of: a step of preparing a monomer composition by mixing a water-soluble ethylenically unsaturated monomer, an internal crosslinking agent, and a polymerization initiator, and a step of forming a polymer by performing thermal polymerization or photopolymerization of the monomer composition. In this regard, the description of the water-soluble ethylenically unsaturated monomer and the internal crosslinking agent refers to those described above.
Here, the water-soluble ethylenically unsaturated monomer has an acidic group. As described above, in the conventional preparation of superabsorbent polymers, an aqueous gel polymer is formed by cross-linking polymerization of monomers in which at least some of the acidic groups are neutralized with a neutralizing agent. Specifically, in the step of mixing the water-soluble ethylenically unsaturated monomer having an acidic group, the internal crosslinking agent, the polymerization initiator, and the neutralizing agent, at least part of the acidic groups of the water-soluble ethylenically unsaturated monomer are neutralized.
However, according to one embodiment of the present invention, the polymer is formed by first conducting polymerization in a state in which the acidic groups of the water-soluble ethylenically unsaturated monomer are not neutralized.
The water-soluble ethylenically unsaturated monomer in which the acidic group is not neutralized (for example, acrylic acid) is in a liquid state at room temperature, and because of its high miscibility with a solvent (water), it exists in the form of a mixed solution in the monomer composition. However, the water-soluble ethylenically unsaturated monomer in which an acidic group is neutralized is solid at room temperature and has different solubility depending on the temperature of the solvent (water), and the lower the temperature, the lower its solubility.
As described, the water-soluble ethylenically unsaturated monomer in which the acidic group is not neutralized has high solubility or miscibility with a solvent (water) as compared with a monomer in which the acidic group is neutralized, and thus it does not precipitate even at low temperature. Thus, it is advantageous for polymerization at low temperature for a long time. Thus, by conducting polymerization for a long period of time using a water-soluble ethylenically unsaturated monomer in which an acidic group is not neutralized, a polymer having a high molecular weight and a uniform molecular weight distribution can be stably formed.
In addition, a long-chain polymer can be formed, and thus an effect of reducing the content of a water-soluble component existing in an uncrosslinked state due to incomplete polymerization or crosslinking can be achieved.
Further, as described, when the monomer in which the acid group is not neutralized is first polymerized to form a polymer, and after neutralization, micronization is performed in the presence of the additive of chemical formula 1, or when micronization is performed in the presence of the additive of chemical formula 1, followed by neutralization, or when both micronization and neutralization of the acid group present in the polymer are performed, a large amount of the additive of chemical formula 1 is present on the surface of the polymer, and can sufficiently exert the effect of reducing the tackiness of the polymer.
Regarding the kind of water-soluble ethylenically unsaturated monomer in the monomer composition, those described in the above description of the superabsorbent polymer composition are also applicable. Further, the concentration of the water-soluble ethylenically unsaturated monomer may be appropriately controlled in consideration of polymerization time, reaction conditions, and the like, and the concentration may be about 20 to about 60 wt%, or about 20 to about 40 wt%.
Regarding the kind of internal crosslinking agent in the monomer composition, those described in the above description of the superabsorbent polymer composition are also applicable. Further, the content of the internal crosslinking agent may be 0.01 to 5 parts by weight with respect to 100 parts by weight of the water-soluble ethylenically unsaturated monomer. For example, the internal crosslinking agent may be used in the following amounts relative to 100 parts by weight of the water-soluble ethylenically unsaturated monomer: 0.01 part by weight or more, 0.05 part by weight or more, or 0.1 part by weight or more, and 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or 0.7 part by weight or less. When the content of the internal crosslinking agent is too low, crosslinking cannot be sufficiently performed, and thus it may be difficult to achieve a strength higher than an appropriate level, whereas when the content of the internal crosslinking agent is too high, it may be difficult to achieve a desired water retention capacity due to an increase in the internal crosslinking density.
In addition, a polymerization initiator is appropriately selected according to the polymerization method. When the thermal polymerization method is employed, a thermal polymerization initiator is used. When a photopolymerization method is employed, a photopolymerization initiator is used. When a hybrid polymerization method (a method using both heat and light) is employed, both a thermal polymerization initiator and a photopolymerization initiator may be used. However, even in the case of the photopolymerization method, a certain amount of heat is generated by light irradiation such as ultraviolet irradiation, and a certain amount of heat is generated as the polymerization reaction (which is an exothermic reaction) proceeds, and therefore, a thermal polymerization initiator may be additionally used.
The photopolymerization initiator may be used without limitation in terms of composition as long as it is a compound capable of forming a radical by light such as ultraviolet rays.
The photopolymerization initiator may include, for example, one or more selected from: benzoin ethers, dialkyl acetophenones, hydroxy alkyl ketones, phenyl glyoxylates, benzyl dimethyl ketals, acyl phosphines, and alpha-amino ketones. Further, specific examples of the acylphosphine may include diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide, phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide, ethyl (2, 4, 6-trimethylbenzoyl) phenylphosphinate, and the like. Further different photopolymerization initiators are well disclosed in "UV Coatings: basic, recent Developments and New Application (Elsevier, 2007)" page 115, written by Reinhold Schwalm, however, the photopolymerization initiators are not limited to the above examples.
Further, as the thermal polymerization initiator, one or more selected from the following may be used: persulfate-based initiators, azo-based initiators, hydrogen peroxide and ascorbic acid. Specific examples of the persulfate-based initiator may include sodium persulfate (Na 2S2O8), potassium persulfate (K 2S2O8), ammonium persulfate ((NH 4)2S2O8) and the like), and examples of the azo-based initiator may include 2, 2-azobis- (2-amidinopropane) dihydrochloride, 2-azobis- (N, N-dimethylene) isobutyramidine dihydrochloride, 2- (carbamoylazo) isobutyronitrile, 2-azobis [2- (2-imidazolin-2-yl) propane ] dihydrochloride, 4-azobis- (4-cyanovaleric acid) and the like.
The polymerization initiator may be used in an amount of 2 parts by weight or less relative to 100 parts by weight of the water-soluble ethylenically unsaturated monomer. In other words, when the concentration of the polymerization initiator is too low, the polymerization rate may become slow, and a large amount of the monomer remaining in the final product may be extracted, which is not preferable. In contrast, when the concentration of the polymerization initiator is higher than the above range, the polymer chain constituting the network becomes shorter, and thus the content of the water-soluble component increases and the physical properties of the polymer may deteriorate, for example, the absorption under pressure decreases, which is not preferable.
The monomer composition may further contain additives such as a thickener, a plasticizer, a storage stabilizer, an antioxidant, and the like, as required.
Furthermore, the monomer composition containing the monomer may be, for example, in a state of a solution thereof dissolved in a solvent (e.g., water). The solid content of the monomer composition in the solution state (i.e., the concentrations of the monomer, the internal crosslinking agent, and the polymerization initiator) can be appropriately controlled in consideration of the polymerization time, the reaction conditions, and the like. For example, the solids content in the monomer composition may be from 10 wt% to 80 wt%, or from 15 wt% to 60 wt%, or from 30 wt% to 50 wt%.
When the solid content of the monomer composition is within the above range, it is possible to facilitate control of the pulverization efficiency during the pulverization of the polymer described later while eliminating the need to remove the monomer unreacted after the polymerization by utilizing the gel effect phenomenon occurring in the polymerization of a high-concentration aqueous solution.
As a suitable solvent, any solvent may be used without limitation in terms of composition as long as it is capable of dissolving the above components. For example, one or more selected from the following may be used in combination: water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1, 4-butanediol, propylene glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate, and N, N-dimethylacetamide.
According to one embodiment of the invention, the step of forming the polymer by carrying out the polymerization of the monomer composition may be carried out in a batch reactor.
Among the usual methods for preparing superabsorbent polymer compositions, polymerization methods are broadly classified into thermal polymerization and photopolymerization according to polymerization energy sources. When the thermal polymerization is carried out, it may be carried out in a reactor equipped with a stirring shaft, such as a kneader. When photopolymerization is carried out, it can be carried out in a reactor equipped with a movable conveyor or in a flat-bottomed container.
Meanwhile, in the polymerization method as described above, a polymer having a small molecular weight and a wide molecular weight distribution is generally formed according to a short polymerization reaction time (for example, 1 hour or less).
Meanwhile, when photopolymerization is performed in a reactor equipped with a movable conveyor belt or in a flat bottom container, the obtained aqueous gel polymer can be generally obtained as a sheet-like aqueous gel polymer having a width of a belt, and the thickness of the polymer sheet can be changed according to the concentration of the monomer composition fed thereto and the feeding speed or feeding amount, and generally, it is obtained in a thickness of about 0.5cm to about 5 cm.
However, when the monomer composition is supplied to such an extent that the thickness of the sheet-like polymer becomes too thin, this is undesirable because production efficiency is low, and when the thickness of the sheet-like polymer is thick for productivity, polymerization reaction may not occur uniformly over the entire thickness, and thus it is difficult to form a high-quality polymer.
Furthermore, in the polymerization in a reactor equipped with a conveyor belt having a stirring shaft, a new monomer composition is fed into the reactor while the polymerization product moves, and thus the polymerization is continuously performed, and polymers having different polymerization rates are mixed. Therefore, uniform polymerization hardly occurs in the entire monomer composition, and the overall physical properties may deteriorate.
In contrast, according to one embodiment of the present invention, since polymerization is performed in a fixed bed manner in a batch reactor, there is little risk of mixing polymers having different polymerization rates, and thus, a polymer having uniform quality can be obtained.
Further, the polymerization step is performed in a batch reactor having a predetermined volume, and it may be performed for a longer time, for example, 3 hours or more, than the polymerization continuously performed in a reactor equipped with a conveyor belt. Although the polymerization time is long as described above, since the polymerization is performed on the water-soluble ethylenically unsaturated monomer in an unneutralized state, the monomer is not easily precipitated even after the long-term polymerization, and thus the long-term polymerization is advantageous.
Meanwhile, in the polymerization in a batch reactor, a thermal polymerization method is employed, and thus a thermal polymerization initiator among the above-mentioned initiators may be used as a polymerization initiator.
Meanwhile, in one embodiment of the present invention, a reducing agent forming a redox pair with an initiator may be introduced to initiate polymerization.
Specifically, when an initiator and a reducing agent are added to the polymer solution, they react with each other to form free radicals.
The radicals formed react with the monomers. Since the oxidation-reduction reaction between initiator and reducing agent is highly reactive, polymerization starts even if only a small amount of initiator and reducing agent is added, and thus there is no need to raise the process temperature. Therefore, low-temperature polymerization can be performed, and variation in physical properties of the polymer solution can be minimized.
The polymerization reaction using the oxidation-reduction reaction can be smoothly performed even at a temperature near or below room temperature (25 ℃). For example, the polymerization reaction may be carried out at a temperature of 5 ℃ or more and 25 ℃ or less, or 5 ℃ or more and 20 ℃ or less.
In one embodiment of the present invention, when a persulfate-based polymerization initiator is used as the initiator, one or more selected from the group consisting of: sodium metabisulfite (Na 2S2O5); tetramethyl ethylenediamine (TMEDA); a mixture of iron (II) sulfate and EDTA (FeSO 4/EDTA); sodium formaldehyde sulfoxylate; disodium 2-hydroxy-2-sulfinylacetate.
For example, potassium persulfate is used as an initiator, and disodium 2-hydroxy-2-sulfinylacetate is used as a reducing agent; or ammonium persulfate as an initiator and tetramethyl ethylenediamine as a reducing agent; alternatively, sodium persulfate may be used as the initiator, and sodium formaldehyde sulfoxylate may be used as the reducing agent.
In another embodiment of the present invention, when a peroxide-based initiator is used as the initiator, one or more selected from the following may be used as the reducing agent: ascorbic acid; sucrose; sodium sulfite (Na 2SO3); sodium metabisulfite (Na 2S2O5); tetramethyl ethylenediamine (TMEDA); a mixture of iron (II) sulfate and EDTA (FeSO 4/EDTA); sodium formaldehyde sulfoxylate; 2-hydroxy-2-sulfinylacetic acid disodium salt; disodium 2-hydroxy-2-sulfoacetate.
Since the polymer obtained by such a method is polymerized using an ethylenically unsaturated monomer in an unneutralized state, as described above, a polymer having a high molecular weight and a uniform molecular weight distribution can be formed, and the content of the water-soluble component can be reduced.
The polymer obtained by such a method may be in a hydrogel state, and its water content may be 30 to 80% by weight. For example, the water content of the polymer may be 30wt% or greater, or 45 wt% or greater, or 50 wt% or greater, and 80 wt% or less, or 70 wt% or less, or 60wt% or less.
When the water content of the polymer is too low, the polymer may not be pulverized efficiently because it is difficult to secure a proper surface area in the subsequent pulverization step. When the water content of the polymer is too high, it is difficult to pulverize the polymer to a desired particle size because the pressure applied in the subsequent pulverization step increases.
Meanwhile, throughout the present specification, "water content" means the weight occupied by water with respect to the total weight of the polymer, which may be a value obtained by subtracting the weight of the dried polymer from the weight of the polymer. Specifically, the water content is defined as a value calculated by measuring a weight loss due to evaporation of water in the polymer during the process of drying by raising the temperature of the polymer in a crumb state through infrared heating. At this time, the drying condition may be determined as follows: the drying temperature was raised from room temperature to about 180 ℃, then the temperature was maintained at 180 ℃, and the total drying time was set to 40 minutes, including 5 minutes of the heating step.
(Step 2 and step 3)
Next, a step of neutralizing at least part of the acidic groups of the polymer (step 2) and a step of preparing base polymer particles by micronizing the polymer in the presence of the additive represented by chemical formula 1 (step 3) are performed.
First, as the neutralizing agent used in step 2, a basic substance capable of neutralizing an acidic group, such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, or the like, may be used.
Further, the degree of neutralization (which refers to the degree to which the acidic groups contained in the polymer are neutralized by the neutralizing agent) may be 50mol% to 90mol%, or 60mol% to 85mol%, or 65mol% to 75mol%. The extent of neutralization may vary depending on the final physical characteristics. However, when the degree of neutralization is too high, the absorbability of the superabsorbent polymer may decrease, and the concentration of carboxyl groups on the surface of the particles is too low, and thus it is difficult to properly perform surface crosslinking in the subsequent process, and the absorption under pressure or the liquid permeability may decrease. In contrast, when the neutralization degree is too low, the absorbency of the polymer is greatly deteriorated, and the polymer may also exhibit characteristics that are difficult to handle, such as characteristics of elastic rubber.
Next, a step of preparing base polymer particles by micronizing the polymer in the presence of the additive represented by chemical formula 1 is performed (step 3).
Here, the steps 2 and 3 may be sequentially performed, simultaneously or alternately performed. In other words, the step of micronizing the polymer (step 3) is performed simultaneously with step 2, or before or after step 2, in the presence of a surfactant.
This step is a step of micronizing the polymer in the presence of the additive of chemical formula 1, and is a step of finely cutting the polymer into a size of several tens to hundreds of micrometers and simultaneously performing aggregation thereof, instead of chopping the polymer into a size of millimeters. In other words, this step is a step of preparing secondary aggregated particles in which primary particles finely cut into a size of several tens micrometers to several hundreds micrometers are aggregated by providing appropriate adhesiveness to the polymer. The base polymer particles prepared by this step, which are secondary aggregated particles, have significantly improved absorption rates due to the large increase in surface area, while having a normal particle size distribution.
As described, after mixing the polymer and the additive of chemical formula 1, the polymer is micronized in the presence of the additive of chemical formula 1 to prepare base polymer particles in the form of secondary aggregated particles, wherein the mixture of superabsorbent polymer particles and the surfactant is finely cut and aggregated.
With respect to the additive represented by chemical formula 1, those described in the above description of the superabsorbent polymer composition may also be applicable.
Here, the "base polymer particles" are particles having a water content of about 30 wt% or more, and since the base polymer particles are particles obtained by finely cutting and agglomerating a polymer into particles without a drying process, the water content thereof may be 30 wt% to 80 wt%, preferably 70 wt% to 80 wt%, like the polymer.
Meanwhile, the additive of chemical formula 1 may be used in an amount of 0.01 to 10 parts by weight with respect to 100 parts by weight of the water-soluble ethylenically unsaturated monomer used in the crosslinking polymerization for preparing the polymer. When the additive of chemical formula 1 is used in an excessively small amount, it cannot be uniformly adsorbed on the polymer surface, and thus re-aggregation of particles may occur after pulverization. When the surfactant is used in an excessively large amount, the overall physical properties of the finally produced superabsorbent polymer may be deteriorated. For example, the additive of chemical formula 1 may be used in the following amounts with respect to 100 parts by weight of the water-soluble ethylenically unsaturated monomer: 0.01 part by weight or more, 0.015 part by weight or more, or 0.1 part by weight or more, and 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less.
The method of mixing the additive of chemical formula 1 with the polymer is not particularly limited as long as it is a method capable of uniformly mixing the surfactant with the polymer, and may be suitably employed and used. Specifically, the additives of chemical formula 1 may be mixed in a dry manner, or mixed in a solution state after being dissolved in a solvent, or the additives of chemical formula 1 may be melted and then mixed.
Among them, for example, the additive of chemical formula 1 may be mixed in a solution state after being dissolved in a solvent. In this regard, any kind of solvent may be used, and there is no limitation on the inorganic or organic solvent, but water is most suitable in view of the easiness of the drying process and the cost of the solvent recovery system. Further, a method of placing the additive of chemical formula 1 and the polymer in a reaction tank and then mixing them, a method of placing the polymer in a mixer and then spraying a solution thereto, or a method of continuously supplying the polymer and the solution into a continuously operated mixer and then mixing them may be used.
Meanwhile, according to an embodiment of the present invention, the steps 2 and 3 may be sequentially performed, simultaneously or alternately performed.
In other words, after neutralizing the acidic group by adding the neutralizing agent to the polymer, the additive of chemical formula 1 may be added to the neutralized polymer to micronize the polymer mixed with the additive, or the polymer may be subjected to neutralization and micronization by simultaneously adding the neutralizing agent and the additive to the polymer. Alternatively, the additives may be added first and then the neutralizing agent may be added. Or the neutralizing agent and the additive may be added alternately. Alternatively, the additives may be added first for micronization, then a neutralizing agent may be added for neutralization, and the additives may be further added to the neutralized aqueous gel polymer for further micronization.
Meanwhile, in order to uniformly neutralize the entire polymer, it may be preferable to have a predetermined time difference between the addition of the neutralizing agent and the micronization process.
At least a portion or a significant amount of the additive of chemical formula 1 may be present on the surface of the base polymer particle.
Here, "the additive of chemical formula 1 is present on the surface of the base polymer particle" means that at least a part or a significant amount of the additive of chemical formula 1 is adsorbed or bound on the surface of the base polymer particle. Specifically, the additive of chemical formula 1 may be physically or chemically adsorbed on the surface of the base polymer particle. More specifically, the hydrophilic functional group of the additive of chemical formula 1 may be physically adsorbed on the hydrophilic portion of the surface of the base polymer particle by intermolecular forces such as dipole-dipole interactions. As described, the hydrophilic portion of the additive of chemical formula 1 is physically adsorbed on the surface of the base polymer particle to cover the surface, and the hydrophobic portion of the additive of chemical formula 1 is not adsorbed on the surface of the base polymer particle, and thus the base polymer particle may be coated with the additive of chemical formula 1 in a micelle structure. This is because the additive of chemical formula 1 is not added during the polymerization process of the water-soluble ethylenically unsaturated monomer, but is added in the micronization step after the formation of the polymer. Compared with the case where the additive of chemical formula 1 is added during the polymerization process and the additive of chemical formula 1 is present inside the polymer, the additive of chemical formula 1 can sufficiently exert its function as a surfactant, and pulverization and aggregation occur simultaneously to obtain particles having a large surface area through aggregation of fine particles.
According to one embodiment, the step of preparing base polymer particles (step 3) may be performed using a micronizing pulverizer.
The micronizing pulverizer may include: a body portion including a transfer space through which a mixture of a polymer and the additive is transferred; a screw member rotatably installed inside the transfer space to transfer the mixture; a driving motor that provides a rotational driving force to the screw member; a cutter member installed in the body portion and including a porous plate having a plurality of holes formed therein, and cutting the mixture while discharging the mixture to the outside of the body portion.
According to one embodiment, steps 2 and 3 may be performed sequentially, simultaneously or alternately, and may be performed using a micronizer.
In this case, the micronizing pulverizer further includes a neutralizer nozzle installed inside the main body portion, and the neutralizer is ejected through the neutralizer nozzle, so that step 2 and step 3 are sequentially, simultaneously or alternately performed.
Specifically, a neutralizing agent is injected into the body portion through a neutralizing agent nozzle to neutralize at least a portion of the acidic groups of the polymer having acidic groups in the mixture. Specifically, in the micronizing pulverizer, a neutralizing agent is injected into the main body portion through a neutralizing agent nozzle to neutralize at least part of the acidic groups of the polymer having acidic groups in the mixture, and at the same time, the mixture is pulverized (micronized) while being discharged to the outside of the main body portion through the porous plate.
Preferably, the neutralizing agent ejected from the neutralizing agent nozzle may be ejected adjacent to the porous plate, and in this case, when the neutralization process is performed and the mixture is simultaneously discharged through the holes of the porous plate, it is preferably used as a slip agent in the mixture to reduce the load of the holes.
Preferably, the cutter member of the micronizing pulverizer includes a porous plate and a cutter blade disposed adjacent to the porous plate and disposed on the outlet side of the main body portion. The mixture passes through a perforated plate and then the mixture is more effectively crushed and micronized by a cutter.
In the micronizing pulverizer, the cutter member may include a plurality of perforated plates and a plurality of cutting knives. The order of arrangement of the plurality of perforated plates and the plurality of cutting blades is not particularly limited, and they may be sequentially disposed, or alternately disposed with each other, or the plurality of perforated plates may be continuously disposed, or the plurality of cutting blades may be continuously disposed.
By including a plurality of perforated plates and cutting knives as described above, micronization can be performed multiple times in a single micronizing pulverizer. Meanwhile, a plurality of neutralizer nozzles may be provided adjacent to any one or more of the plurality of perforated plates and the cutter, and in terms of improving the slip characteristics, it is preferable that the neutralizer nozzles are provided adjacent to the perforated plates.
In the micronizer, the size of the pores formed in the porous plate may be 0.1mm to 30mm, preferably 0.5mm to 25mm, 1mm to 20mm, or 1mm to 10mm. When a porous plate having the pore size is used, base polymer particles having a desired particle size can be prepared. As described above, when the cutter member includes a plurality of porous plates, the sizes of the holes formed in each porous plate may satisfy the above range, and they may be the same as or different from each other.
According to one embodiment of the invention, step 3 may be performed a plurality of times using a plurality of micronizing pulverizers or a single micronizing pulverizer comprising a plurality of perforated plates and/or a plurality of cutting knives. Or some of the plurality of micronizing pulverizers may include a plurality of perforated plates and/or a plurality of cutting knives. The micronization step may preferably be performed 1 to 6 times or 1 to 4 times. When step 3 is performed a plurality of times, the additive may be additionally injected a plurality of times.
The step of preparing base polymer particles by micronizing the polymer (step 3) may be performed such that the base polymer particles are micronized to an average particle size of 50 μm to 600 μm, preferably 100 μm to 500 μm, 150 μm to 450 μm, or 200 μm to 400 μm. By satisfying the above particle size range, when the polymer is prepared as secondary particles in the form of aggregates of primary particles and then subjected to the pulverizing and drying process under milder conditions, the amount of fine particles generated during the process can be significantly reduced.
As used herein, the average particle size "Dn" means the particle size or particle diameter at the point where the cumulative distribution of the number of particles according to the particle size is n%. In other words, D50 represents the particle size at the point where the cumulative distribution of the number of particles according to the particle size is 50%, D90 represents the particle size at the point where the cumulative distribution of the number of particles according to the particle size is 90%, and D10 represents the particle size at the point where the cumulative distribution of the number of particles according to the particle size is 10%. Dn can be measured using laser diffraction methods. Specifically, after the powder to be measured is dispersed in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring apparatus (e.g., microtrac S3500) to measure a difference in diffraction pattern according to particle size when particles pass through a laser beam, thereby calculating particle size distribution. D10, D50 and D90 can be measured by calculating the particle sizes at points where the cumulative distribution of the particle numbers according to the particle sizes in the measuring apparatus is 10%, 50% and 90%.
(Step 4)
Next, a step of drying the base polymer particles is included (step 4). By this step, a superabsorbent polymer composition including superabsorbent polymer particles and an additive represented by chemical formula 1 can be prepared.
The drying may be performed such that the water content of the plurality of superabsorbent polymer particles included in the produced superabsorbent polymer composition is about 10wt% or less, specifically about 0.1 wt% to about 10wt%, respectively.
At this time, the drying of the crushed product may be performed in a mobile manner. Mobile drying is distinguished from fixed bed drying depending on whether the material flows during drying.
In a common method of preparing superabsorbent polymers, the drying step is typically performed until the water content of the superabsorbent polymer particles is less than 10 wt.%. In contrast, in the present invention, aggregation is controlled by performing the step of micronization in the presence of the additive of chemical formula 1, and thus drying is performed such that the water content of the dried superabsorbent polymer particles is 10 to 20 wt%, preferably 10 to 25 wt%. However, the present invention is not limited thereto. Thus, there are advantages in that: due to the high water content, the generation of fine particles can be substantially prevented. Furthermore, the absorption rate of the final superabsorbent polymer composition may preferably be improved.
For this purpose, the drying step is carried out in a mobile manner at a relatively low temperature. The mobile drying is distinguished from the fixed bed drying according to whether the material flows during drying or not, and preferably prevents aggregation phenomenon between fine-cut aqueous superabsorbent polymer particles in the pulverized product to be dried, and completes drying in a short time.
For this purpose, the drying step is carried out in a mobile manner at a relatively low temperature. The mobile drying is distinguished from the fixed bed drying according to whether the material flows during drying, and preferably prevents aggregation phenomenon between finely cut base polymer particles in the pulverized product to be dried, and completes drying in a short time.
Specifically, mobile drying refers to a method of drying a dry product under mechanical agitation. At this time, the direction of the hot air passing through the material may be the same as or different from the circulation direction of the material. Or the material may be dried by circulating the material inside the dryer and passing the heating medium fluid (heating medium oil) through a separate pipe outside the dryer. In contrast, fixed bed drying refers to a process in which: wherein the material to be dried is fixed on a base plate such as a porous iron plate through which air can pass, and dried by passing hot air through the material from the bottom to the top.
In the step of drying the base polymer particles (step 4), a commonly used mobile dryer may be used without particular limitation. For example, a mobile dryer such as a horizontal mixer, rotary kiln, paddle dryer, or steam tube dryer may be used to perform this step.
The drying step (step 4) may be performed at a relatively low temperature of 150 ℃ or less, preferably at 100 ℃ to 150 ℃, 100 ℃ to 130 ℃, 105 ℃ to 115 ℃, and superabsorbent polymer particles having desired particle size and physical properties may be produced without aggregation even when the drying step is performed at a low temperature as described above.
Meanwhile, the drying temperature may be an internal operation temperature of the mobile dryer into which the dry product is injected, and the drying temperature may be controlled by passing a heating medium fluid (heating medium oil) through a separate pipe outside the dryer, but is not limited thereto.
The drying step (step 4) may be performed for 30 minutes to 80 minutes, and may be performed for 30 minutes to 60 minutes, or 40 minutes to 50 minutes. Since the aggregation phenomenon between finely cut polymer resin particles in the pulverized product to be dried is small, superabsorbent polymer particles having desired particle size and physical properties can be produced even if the drying step is performed at a relatively low temperature for a short time.
(Additional steps)
Thereafter, the method of preparing a superabsorbent polymer composition according to an embodiment of the present invention may further include the step of pulverizing and classifying the superabsorbent polymer particles, as needed.
Specifically, the pulverizing step may be performed such that the dry superabsorbent polymer particles are pulverized to have a particle size of normal particles, i.e., a particle size of 150 μm to 850 μm.
The pulverizer used for this purpose may specifically include a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary chopper, a chopper (cutter mill), a disc mill, a chip breaker, a crusher, a chopper (chopper), a disc cutter, or the like, but is not limited to the above examples.
Alternatively, as the pulverizer, a pin mill, a hammer mill, a screw mill, a roller mill, a disk mill, a click mill, or the like may be used, but is not limited to the above examples.
On the other hand, in the production method of the present invention, by the micronization step, superabsorbent polymer particles having a narrower particle size distribution than in the conventional shredding step can be achieved, and when the mobile drying is performed, the water content after drying is maintained at a relatively high 10% by weight or more. Therefore, even if the pulverization is performed under mild conditions of low pulverizing power, a super absorbent polymer having a very high content of normal particles of 150 μm to 850 μm can be formed, and the generation rate of fine particles can be greatly reduced.
The superabsorbent polymer particles prepared as above may comprise superabsorbent polymer particles having a particle size of from 150 μm to 850 μm, i.e. normal particles, in the following amounts relative to the total weight: 80 wt% or more, 85 wt% or more, 89 wt% or more, 90 wt% or more, 92 wt% or more, 93 wt% or more, 94 wt% or more, or 95 wt% or more. The above particle sizes of the polymer particles can be measured according to the European disposables and nonwovens Association (EDANA) standard WSP 220.3 method.
Furthermore, the superabsorbent polymer particles may comprise fine particles having a particle size of less than 150 μm in the following amounts relative to the total weight: less than about 20 wt%, less than about 18 wt%, less than about 15 wt%, less than about 13 wt%, less than about 10 wt%, specifically less than about 5 wt%, more specifically less than about 3 wt%. This is in contrast to conventional methods of preparing superabsorbent polymers in which more than about 20% to about 30% by weight of fine particles are produced.
Next, the method of preparing a superabsorbent polymer according to an embodiment of the present invention may include a step of preparing superabsorbent polymer particles by thermally crosslinking the surfaces of base polymer particles in the presence of a surface crosslinking agent.
The surface crosslinking step serves to initiate a crosslinking reaction on the surface of the base polymer powder in the presence of a surface crosslinking agent, and the unsaturated bond of the water-soluble ethylenically unsaturated monomer remaining uncrosslinked on the surface can be crosslinked by the surface crosslinking agent, and thus, a superabsorbent polymer having an increased surface crosslinking density can be formed.
Specifically, the surface cross-linked layer may be formed by a heat treatment process in the presence of a surface cross-linking agent, and the heat treatment process increases the surface cross-linked density, i.e., the outer cross-linked density, while the inner cross-linked density is unchanged. The superabsorbent polymer in which the surface cross-linked layer is formed may have a structure in which the outer cross-linked density is higher than the inner cross-linked density.
The surface cross-linking process may be performed at a temperature of 80 to 250 ℃. More specifically, the surface cross-linking process may be performed at a temperature of 100 ℃ to 220 ℃, or 120 ℃ to 200 ℃ for about 20 minutes to about 2 hours, or about 40 minutes to about 80 minutes. When the conditions of the above surface crosslinking process are satisfied, the surfaces of the superabsorbent polymer particles can be sufficiently crosslinked to increase the absorption under pressure.
By satisfying these surface crosslinking process conditions (in particular, heating conditions and reaction conditions at the highest reaction temperature), it is possible to produce a superabsorbent polymer which appropriately satisfies physical properties such as excellent absorption rate and the like.
The heating means for the surface crosslinking reaction is not particularly limited. Heating may be performed by providing a heating medium or by directly providing a heat source. In this regard, the type of heating medium suitable for use may be steam, hot air, hot fluid such as hot oil, etc., but is not limited thereto. Further, the temperature of the heating medium to be supplied may be appropriately selected in consideration of the manner of heating the medium, the heating rate, and the heating target temperature. Meanwhile, as a directly supplied heat source, an electric heating or gas heating method may be used, but is not limited to the above examples.
Meanwhile, as the surface cross-linking agent contained in the surface cross-linking agent composition, any surface cross-linking agent conventionally used for producing superabsorbent polymers may be used without any particular limitation. For example, the surface cross-linking agent may include: one or more polyhydric alcohols selected from the group consisting of ethylene glycol, propylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, 1, 2-hexanediol, 1, 3-hexanediol, 2-methyl-1, 3-propanediol, 2, 5-hexanediol, 2-methyl-1, 3-pentanediol, 2-methyl-2, 4-pentanediol, tripropylene glycol, and glycerin; one or more carbonate-based compounds selected from ethylene carbonate and propylene carbonate; epoxy compounds such as ethylene glycol diglycidyl ether and the like; oxazoline compounds, e.g./> Oxazolidinones and the like; a polyamine compound; /(I)An oxazoline compound; singleOxazolidinone, diOxazolidinone or polyAn oxazolidinone compound; a cyclic urea compound; etc. Preferably, the same ones as the above-mentioned internal crosslinking agents can be used, for example, diglycidyl ether-based compounds of alkylene glycol such as ethylene glycol diglycidyl ether and the like can be used.
In the surface crosslinking step, a surface crosslinking agent composition containing an alcohol-based solvent and water in addition to the surface crosslinking agent may be used.
Such a surface cross-linking agent may be used in an amount of 0.001 parts by weight to 2 parts by weight relative to 100 parts by weight of the superabsorbent polymer particles. Preferably, the surface cross-linking agent may be used in the following amounts: 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.02 parts by weight or more, and 0.5 parts by weight or less, 0.3 parts by weight or less. By controlling the content range of the surface cross-linking agent within the above range, it is possible to produce a superabsorbent polymer exhibiting excellent overall physical properties such as absorption performance, liquid permeability, and the like.
Meanwhile, a surface cross-linking agent is added to the superabsorbent polymer particles in the form of a surface cross-linking agent composition comprising the same. The method of adding the surface cross-linking agent composition is not particularly limited. For example, a method of placing and mixing the surface-crosslinking agent composition and the superabsorbent polymer particles in a reactor, a method of spraying the surface-crosslinking agent composition onto the superabsorbent polymer particles, a method of continuously feeding and mixing the superabsorbent polymer particles and the surface-crosslinking agent composition into a continuously running mixer, and the like can be used.
The surface cross-linker composition may also comprise water and/or a hydrophilic organic solvent as a medium. Thus, it is advantageous that the surface cross-linking agent can be uniformly dispersed on the base polymer powder. At this time, in order to cause uniform dissolution/dispersion of the surface cross-linking agent, prevent aggregation phenomenon of the base polymer powder, and simultaneously optimize the surface penetration depth of the surface cross-linking agent, the contents of water and hydrophilic organic solvent may be preferably controlled with respect to 100 parts by weight of the super absorbent polymer particles.
Meanwhile, in the method of preparing a superabsorbent polymer according to an embodiment of the present invention, in order to further improve liquid permeability and the like, aluminum salts such as aluminum sulfate and other various multivalent metal salts may also be used during surface crosslinking. These multivalent metal salts may be included on the surface crosslinked layer of the finally prepared superabsorbent polymer.
According to one embodiment of the present invention, after the step of forming the surface cross-linked layer on at least part of the surface of the superabsorbent polymer particles, any one or more of the following may be further included: a cooling step of cooling the superabsorbent polymer particles having the surface cross-linked layer formed thereon, a hydration step of adding water to the superabsorbent polymer particles having the surface cross-linked layer formed thereon, and a post-treatment step of adding an additive to the superabsorbent polymer particles having the surface cross-linked layer formed thereon. In this regard, the cooling step, the hydrating step, and the post-treatment step may be performed sequentially or simultaneously.
The additives injected in the post-treatment step may include a liquid permeability improver, an anti-blocking agent, a fluidity improver, an antioxidant, etc., but the present invention is not limited thereto.
By selectively performing the cooling step, the hydration step and the post-treatment step, the water content of the final superabsorbent polymer can be improved and superabsorbent polymer articles having higher quality can be manufactured.
According to another embodiment of the present invention, there is provided a superabsorbent polymer composition prepared by the above preparation method.
The superabsorbent polymer composition prepared by the above preparation method can achieve high water content without a separate additional hydration process or additive injection process, and thus can provide a superabsorbent polymer: which has a low content of fine particles and has a water retention capacity (CRC) and Absorbency Under Pressure (AUP), which are general absorption characteristics, equal to or higher than that of the super absorbent polymer prepared by the conventional method, and at the same time has an excellent absorption rate due to a low content of the water-soluble component (EC).
Hereinafter, the actions and effects of the present invention will be described in more detail with reference to specific exemplary embodiments thereof. However, these exemplary embodiments are provided only to illustrate the present invention, and the scope of the present invention is not limited thereto.
EXAMPLE preparation of superabsorbent Polymer composition
Example 1
(Step 1) in a 5L glass vessel equipped with a stirrer and a thermometer, 1,000g of acrylic acid, 3.5g of pentaerythritol triallyl ether as an internal crosslinking agent and 2,260g of water were mixed and stirred while being maintained at 5 ℃.1,000 cc/min of nitrogen was introduced into the glass vessel containing the mixture for 1 hour and replaced with nitrogen. Next, 13g of a 0.3% aqueous hydrogen peroxide solution, 15g of a 1% aqueous ascorbic acid solution and 30g of a 2% aqueous 2,2' -azobis- (2-amidinopropane) dihydrochloride solution as polymerization initiators were added, and simultaneously 15g of a 0.01% aqueous sulfuric acid solution as a reducing agent was added to initiate polymerization. After the temperature of the mixture reached 85 ℃, polymerization was carried out at 90±2 ℃ for about 3 hours to obtain a polymer. The water content of the polymer was about 70 wt%.
(Step 2 and step 3) 1.19g of Compound A-1 of Table 1 as an additive of chemical formula 1 was subjected to water dispersion (preparation of 2 wt% aqueous dispersion) in 52.27g of water, and then mixed with 1,000g of the polymer obtained in step 1.
The first micronization process was carried out by passing the mixture once through a first micronizer equipped with a porous plate containing a large number of holes with a hole size of 6 mm.
Next, the second, third and fourth micronization processes were performed by passing the mixture through a second micronizer equipped with a porous plate containing a large number of holes with a hole size of 4mm three times in total.
In the second micronization process, 400g of 32% aqueous naoh solution was injected through a neutralizer nozzle disposed adjacent to the porous plate, and the neutralization process was performed together with the micronization.
In the third micronization process, 37.5g of 15% na 2SO4 aqueous solution was injected through a neutralizer nozzle disposed adjacent to the porous plate, and the neutralization process was performed together with the micronization.
In the final fourth micronization process, the micronization process is performed without the addition of neutralizing agents or surfactants to obtain base polymer particles.
The degree of neutralization of the base polymer particles was 70mol%.
(Step 4) then, 1,000g of base polymer particles were placed in a rotary mixer mobile dryer rotating at 100 rpm. The drying was performed for 60 minutes while maintaining the internal temperature of the dryer at 105 c, thereby obtaining superabsorbent polymer particles. The superabsorbent polymer particles had a water content of 11% by weight.
Example 2
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-2 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 11% by weight.
Example 3
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-3 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 11% by weight.
Example 4
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-4 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 11% by weight.
Example 5
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-5 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 14% by weight.
Example 6
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-6 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 14% by weight.
Example 7
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-7 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 11% by weight.
Example 8
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-8 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 12% by weight.
Example 9
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-9 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 13% by weight.
Example 10
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-10 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 11% by weight.
Example 11
(Step 1) in a 5L glass vessel equipped with a stirrer and a thermometer, 1,000g of acrylic acid, 3.5g of pentaerythritol triallyl ether as an internal crosslinking agent and 2,260g of water were mixed and stirred while being maintained at 5 ℃.1,000 cc/min of nitrogen was introduced into the glass vessel containing the mixture for 1 hour and replaced with nitrogen. Next, 13g of a 0.3% aqueous hydrogen peroxide solution, 15g of a 1% aqueous ascorbic acid solution and 30g of a 2% aqueous 2,2' -azobis- (2-amidinopropane) dihydrochloride solution as polymerization initiators were added, and simultaneously 15g of a 0.01% aqueous sulfuric acid solution as a reducing agent was added to initiate polymerization. After the temperature of the mixture reached 85 ℃, polymerization was carried out at 90±2 ℃ for about 3 hours to obtain a polymer. The water content of the polymer was about 70 wt%.
(Step 2 and step 3) 0.595g of compound A-1 of Table 1 as an additive of chemical formula 1 was subjected to water dispersion (preparation of 2 wt% aqueous dispersion) in 52.27g of water, and then mixed with 1,000g of the polymer obtained in step 1.
The first micronization process was carried out by passing the mixture once through a first micronizer equipped with a porous plate containing a large number of holes with a hole size of 6 mm.
Next, the second, third and fourth micronization processes were performed by passing the mixture through a second micronizer equipped with a porous plate containing a large number of holes having a hole diameter of 4mm three times in total.
In the second micronization process, 400g of 32% aqueous naoh solution was injected through a neutralizer nozzle disposed adjacent to the porous plate, and the neutralization process was performed together with the micronization.
In the third micronization process, 37.5g of 15% na 2SO4 aqueous solution was injected through a neutralizer nozzle disposed adjacent to the porous plate, and the neutralization process was performed together with the micronization.
In the final fourth micronization process, 0.595g of compound a-11 of table 1 as an additive of chemical formula 1 was water-dispersed in 52.27g of water (to prepare a2 wt% aqueous dispersion), and injected into a second micronizer containing a mixture subjected to third micronization, and subjected to a fourth micronization process to prepare base polymer particles. The degree of neutralization of the base polymer particles was 70mol%.
(Step 4) then, 1,000g of base polymer particles were placed in a rotary mixer mobile dryer rotating at 100 rpm. The drying was performed for 60 minutes while maintaining the internal temperature of the dryer at 105 c, thereby obtaining superabsorbent polymer particles.
After step 4, the final superabsorbent polymer particles had a water content of 12% by weight.
Example 12
A superabsorbent polymer composition was prepared in the same manner as in example 11 except that in example 11, compound A-1 was used as additive of formula 1 in the first micronization step and compound A-2 of Table 1 was used as additive of formula 1 in the fourth micronization step.
After drying in step 4, the final superabsorbent polymer particles had a water content of 10% by weight.
Example 13
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-12 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 14% by weight.
Example 14
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that in example 1, compound A-13 of Table 1 was used as an additive of formula 1 instead of compound A-1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 14% by weight.
Example 15
A superabsorbent polymer composition was prepared in the same manner as in example 1 except that 0.595g of compound A-12 used in example 13 and 0.595g of compound A-13 used in example 14 were mixed, using a total of 1.19g of additive as additive of formula 1.
After drying in step 4, the final superabsorbent polymer particles had a water content of 13% by weight.
Example 16
A super absorbent polymer composition was prepared in the same manner as in example 13, except that in example 13, the amount of A-12 as an additive of chemical formula 1 was increased to 2.38g.
After drying in step 4, the final superabsorbent polymer particles had a water content of 12% by weight.
Comparative example 1
Superabsorbent polymer compositions were prepared in the same manner as in example 1 except that the additive of formula 1 was not used in example 1.
Comparative examples 2 to 6, 8 and 9
Each superabsorbent polymer composition was prepared in the same manner except that in example 1, the additives described in table 1 below were used as the additives of chemical formula 1.
Comparative example 7
In a 3L glass vessel equipped with a stirrer and a thermometer, 100g (1.388 mol) of acrylic acid, 0.16g of polyethylene glycol diacrylate (mn=508) as an internal crosslinking agent, 0.008g of diphenyl (2, 4, 6-trimethylbenzoyl) -phosphine oxide as a photopolymerization initiator, 0.12g of sodium persulfate as a thermal polymerization initiator, and 123.5g of a 32% caustic soda solution were mixed at room temperature to prepare a monomer composition (neutralization degree of acrylic acid: 70mol%, solid content: 45 wt%).
Thereafter, the monomer composition was fed at a rate of 500 mL/min to 2000 mL/min on a conveyor belt, and the conveyor belt having a width of 10cm and a length of 2m was rotated at a speed of 50 cm/min. Then, the polymerization reaction was allowed to proceed for 60 seconds by irradiating ultraviolet rays having an intensity of 10mW/cm 2 while feeding the monomer composition, thereby obtaining an aqueous gel polymer having a water content of 55% by weight.
Next, the aqueous gel polymer obtained by the polymerization reaction was pulverized without additives using a meat grinder. At this time, the water content of the aqueous superabsorbent polymer particles contained in the final pulverized product was 55% by weight.
Next, the pulverized product was dried using a convection oven capable of moving a gas flow up and down by flowing hot air of 185 ℃ for 20 minutes from bottom to top and 20 minutes from top to bottom, and as a result, a superabsorbent polymer in which the water content of the final superabsorbent polymer particles after drying was 25 wt% was produced.
TABLE 1
Experimental example
The particle aggregation characteristics, centrifuge Retention Capacity (CRC), absorbency Under Pressure (AUP), absorption rate, and effective absorbency of the superabsorbent polymer compositions prepared in examples and comparative examples, respectively, were measured by the following methods, and the results are shown in tables 3 and 4 below. Unless otherwise indicated, the following evaluations of physical properties were all carried out at constant temperature and humidity (23.+ -. 2 ℃ C., relative humidity 45.+ -. 10%). In order to prevent measurement errors, an average value of three measurements is used as measurement data. Further, physiological saline or saline used in the following evaluation of physical properties means 0.9% by weight aqueous sodium chloride (NaCl).
(1) Evaluation of particle aggregation Properties
① Preparation of 1,000g of the unneutralized polymer of step 1 (water content 70% by weight) prepared in each of the examples and comparative examples.
② Next, 0.36g of the additive of chemical formula 1 or the corresponding comparative compound was dispersed in 17.54g of 80℃water (2.04 wt% aqueous dispersion was prepared) and mixed with 300g of the polymer obtained in step 1.
The additives of step 2 or the corresponding comparative compounds were mixed in the form of aqueous solutions according to the kind and content used in each of the examples and comparative examples.
② 300G of the mixture was put into a mincing machine comprising a perforated plate having a cavity of 3mm ψ and a thickness of 5T, and then pulverized.
③ For the crushed product, visual evaluation of discharge time, discharge amount, and aggregation according to the evaluation criteria in table 2 below was performed, and the results are shown in table 3.
At this time, the discharge time means a time (seconds) taken for 200g of the pulverized product to be discharged from the mincing machine, and the discharge time is shortened as aggregation is lessened.
The discharge amount means a ratio (wt%) of the amount discharged through the discharge port with respect to 300g of the injected mixture after completion of step ②, and as aggregation is lessened, the amount of the remaining pieces inside the mincing machine decreases, and thus the discharge amount increases.
Further, photographs of examples of evaluation criteria o and X as visual evaluation of aggregation are shown in (a) and (b) of fig. 2, respectively.
TABLE 2
TABLE 3
Referring to table 3 and fig. 2, it was determined that when pulverization was performed by adding an unneutralized polymer and the additive of chemical formula 1 of the present invention, aggregation between particles after pulverization was suppressed, discharge time was short, and discharge amount was remarkable, as compared with the case of using no additive or using a compound not conforming to the structure. It was also determined that the adhesiveness and cohesiveness of the mixture introduced into the mincing machine were reduced by the additive of chemical formula 1 of the present invention, and thus 80% or more of the discharged product was discharged in the form of 1cm particles, which was confirmed during visual evaluation.
(2) Centrifuge Retention Capacity (CRC)
The Centrifuge Retention Capacity (CRC) of the absorbency under no load of each polymer composition was measured according to European disposables and nonwovens Association (EDANA) standard EDANA WSP 241.3.
In detail, from the superabsorbent polymer compositions obtained by examples and comparative examples, polymers screened with #30 to #50 sieve were obtained. Polymer W 0 (g) (about 0.2 g) was uniformly placed into a bag made of nonwoven fabric, followed by sealing. Then, the bag was immersed in a physiological saline solution (0.9 wt%) at room temperature. After 30 minutes, water was removed from the bag using a centrifuge at 250G for 3 minutes, and then the weight of the bag W 2 (G) was measured. Further, the same procedure was performed without using a polymer, and then the resulting weight W 1 (g) was measured.
By using the respective weights thus obtained, CRC (g/g) was calculated according to the following equation 1, and the results are shown in table 4.
[ Equation 1]
CRC(g/g)＝{[W2(g)-W1(g)]/W0(g)}-1
(3) Absorption Under Pressure (AUP)
The absorption at 0.7psi pressure of the superabsorbent polymer compositions of the examples and comparative examples were measured according to EDANA method WSP 242.3.
First, when measuring the absorption under pressure, the fractionated polymer used in the CRC measurement is used.
In detail, a 400 mesh stainless steel mesh was mounted on the bottom of a plastic cylinder having an inner diameter of 25 mm. Superabsorbent polymer composition W 0 (g) (0.16 g) was uniformly spread on a stainless steel mesh at room temperature and 50% humidity. A piston capable of uniformly providing a load of 0.7psi was placed thereon, with an outer diameter of the piston slightly less than 25mm, without a gap between the inner wall of the cylinder and the piston, and without impeding the up-and-down movement of the cylinder. At this time, the weight W 3 (g) of the apparatus was measured.
After placing a glass filter having a diameter of 90mm and a thickness of 5mm in a petri dish having a diameter of 150mm, a physiological saline solution composed of 0.9 wt% sodium chloride was poured until the surface level of the physiological saline solution became flush with the upper surface of the glass filter. A piece of filter paper with a diameter of 90mm was placed on the glass filter. The measuring device was mounted on a filter paper to absorb the liquid under load for 1 hour. After 1 hour, the weight W 4 (g) was measured after lifting the measuring device.
The absorption under pressure (g/g) was calculated from the obtained weight according to the following equation 2, and the results are shown in table 4.
[ Equation 2]
AUP(g/g)＝[W4(g)-W3(g)]/W0(g)
(4) Surface tension (S/T)
To measure the surface tension of the superabsorbent polymer compositions of examples and comparative examples, 0.5g of each superabsorbent polymer composition was added to 40mL of 0.9% brine and stirred at 350rpm for 3 minutes. After stopping the stirring, brine containing the swollen superabsorbent polymer is obtained. The surface tension of each superabsorbent polymer composition was measured using a surface tensiometer (product name: force Tensiometer-K100, manufactured by KRUSS) using saline as a measurement sample, and the results are shown in Table 4.
(5) Bulk Density (BD)
100G of each of the superabsorbent polymer compositions of examples and comparative examples was passed through the orifice of a standard flowability measuring device and placed in a container having a volume of 100ml. Thereafter, the superabsorbent polymer composition was cut to a level and the volume of the superabsorbent polymer composition was adjusted to 100ml. Then, the weight of the superabsorbent polymer composition alone excluding the container was measured. The weight of the superabsorbent polymer composition alone is then divided by 100ml, which is the volume of the superabsorbent polymer composition, to obtain a bulk density corresponding to the weight of superabsorbent polymer composition per unit volume.
(6) Amount of fine particles produced
The amounts of fine particles produced in each of the superabsorbent polymer compositions prepared in examples and comparative examples were calculated as the ratio of the weight of the polymer having a particle size of less than 150 μm to the total weight after passing the prepared superabsorbent polymer composition through a coarse pulverizer (2800 rpm,0.4mm gap, 1mm lower mesh condition) once, and the results are shown in table 4.
(7) Absorption Rate (vortex time)
The absorption rate (vortex time) of the superabsorbent polymer compositions of examples and comparative examples was measured by the following method, and the results are shown in table 4.
① First, 50mL of 0.9% brine was placed in a 100mL flat bottom beaker using a 100mL graduated cylinder (MASS CYLINDER).
② Next, a beaker was placed in the center of the magnetic stirrer, and then a magnetic bar (diameter 8mm and length 30 mm) was placed in the beaker.
③ Then, the stirrer was operated such that the magnetic bar was stirred at 600rpm, and the bottommost part of the vortex generated by the stirring was brought into contact with the top of the magnetic bar.
④ After determining that the temperature of the brine in the beaker reached 24.0 ℃, a sample of 2±0.01g of superabsorbent polymer composition was introduced and a stopwatch was simultaneously operated. The time taken for the vortex to disappear and the liquid surface to be perfectly level was measured in seconds and determined as the absorption rate.
TABLE 4
Referring to table 4, when the super absorbent polymer composition is prepared by adding the unneutralized polymer and the additive of chemical formula 1 of the present invention, aggregation between particles after pulverization is suppressed, and a composition comprising the super absorbent polymer particles of a desired particle size can be prepared without an additional pulverization process after drying, and thus, generation of fine particles is reduced as compared with the case of using no additive, or using a compound that does not conform to a structure, or mixing the neutralized aqueous gel polymer. Thus, it was determined that the superabsorbent polymer composition of the example had a significantly faster absorption rate than the superabsorbent polymer composition of the comparative example, and exhibited a high bulk density without a decrease in surface tension while having an equivalent or higher water holding capacity and absorbency under pressure.
Claims (19)
1. A superabsorbent polymer composition comprising:
Superabsorbent polymer particles comprising a crosslinked polymer of a water-soluble ethylenically unsaturated monomer having an acidic group and an internal crosslinking agent; and
An additive represented by the following chemical formula 1:
[ chemical formula 1]
In the chemical formula 1, the chemical formula is shown in the drawing,
A 1、A2 and A 3 are each independently a single bond, carbonyl group, Provided that one or more of A 1、A2 and A 3 is carbonyl orWherein m1, m2 and m3 are each independently integers from 1 to 8,Is linked to an adjacent oxygen atom, respectively to adjacent R 1、R2 and R 3,
R 1、R2 and R 3 are each independently hydrogen, a linear or branched alkyl group having 6 to 18 carbon atoms, or a linear or branched alkenyl group having 6 to 18 carbon atoms, and
N is an integer from 1 to 9.
2. The superabsorbent polymer composition according to claim 1, wherein the additive is one or more selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-14:
[ chemical formula 1-1]
[ Chemical formulas 1-2]
[ Chemical formulas 1-3]
[ Chemical formulas 1-4]
[ Chemical formulas 1-5]
[ Chemical formulas 1-6]
[ Chemical formulas 1-7]
[ Chemical formulas 1-8]
[ Chemical formulas 1-9]
[ Chemical formulas 1-10]
[ Chemical formulas 1-11]
[ Chemical formulas 1-12]
[ Chemical formulas 1-13]
[ Chemical formulas 1-14]
3. The superabsorbent polymer composition according to claim 1, wherein said additive is contained in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of said water-soluble ethylenically unsaturated monomer.
4. The superabsorbent polymer composition according to claim 1, further comprising a surface cross-linked layer formed on at least part of the surface of the superabsorbent polymer particles by further cross-linking the cross-linked polymer via a surface cross-linking agent.
5. The superabsorbent polymer composition according to claim 1, wherein the superabsorbent polymer composition has an absorption rate (vortex time) of 30 seconds or less at 24.0 ℃ according to the vortex method.
6. The superabsorbent polymer composition according to claim 1, wherein the superabsorbent polymer composition has a Centrifuge Retention Capacity (CRC) according to EDANA WSP 241.3 of 39.0g/g or more.
7. The superabsorbent polymer composition according to claim 1, wherein said superabsorbent polymer composition has an absorbency under 0.7psi pressure (AUP) of 24.0g/g or more for the EDANA method WSP 242.3.
8. A method of preparing a superabsorbent polymer composition, the method comprising the steps of:
forming a polymer by cross-linking polymerizing a water-soluble ethylenically unsaturated monomer having an acidic group in the presence of an internal cross-linking agent and a polymerization initiator (step 1);
neutralizing at least part of the acidic groups of the polymer (step 2);
Preparing base polymer particles by micronizing the polymer in the presence of an additive represented by the following chemical formula 1 (step 3); and
Drying the base polymer particles (step 4):
[ chemical formula 1]
In the chemical formula 1, the chemical formula is shown in the drawing,
A 1、A2 and A 3 are each independently a single bond, carbonyl group, Provided that one or more of A 1、A2 and A 3 is carbonyl orWherein m1, m2 and m3 are each independently integers from 1 to 8,Is linked to an adjacent oxygen atom, respectively to adjacent R 1、R2 and R 3,
R 1、R2 and R 3 are each independently hydrogen, a linear or branched alkyl group having 6 to 18 carbon atoms, or a linear or branched alkenyl group having 6 to 18 carbon atoms, and
N is an integer from 1 to 9.
9. The method of claim 8, wherein the step of forming the polymer (step 1) is performed in a batch reactor.
10. The method of claim 8, wherein the step 2 and the step 3 are performed sequentially, simultaneously or alternately.
11. The method of claim 8, wherein the additive is included in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of the water-soluble ethylenically unsaturated monomer.
12. The method of claim 8, wherein the step of preparing the base polymer particles (step 3) is performed using a micronizing pulverizer comprising:
A body portion including a transfer space through which the mixture of the polymer and the additive is transferred;
a screw member rotatably installed inside the transfer space to transfer the mixture;
a drive motor that provides a rotational drive force to the screw member; and
A cutter member mounted in the body portion and including a porous plate having a plurality of holes formed therein, and cutting the mixture when the mixture is discharged to the outside of the body portion.
13. The method of claim 8, wherein the step 2 and the step 3 are performed sequentially, simultaneously or alternately, and the step 2 and the step 3 are performed using a micronizer comprising:
A body portion including a transfer space through which the mixture of the polymer and the additive is transferred;
a screw member rotatably installed inside the transfer space to transfer the mixture;
a drive motor that provides a rotational drive force to the screw member;
A cutter member installed in the body part and including a porous plate having a plurality of holes formed therein, and cutting the mixture while discharging the mixture to the outside of the body part; and
And a neutralizer nozzle mounted inside the main body portion.
14. The method of claim 13, wherein in the micronizer, the neutralizing agent is injected into the body portion through the neutralizing agent nozzle to neutralize at least a portion of the acidic groups of the polymer having the acidic groups in the mixture.
15. The method of claim 12, wherein the pores formed in the porous plate have a size of 0.1mm to 30mm.
16. The method of claim 8, wherein the step of drying the base polymer particles (step 4) is performed in a mobile manner.
17. The method of claim 8, wherein the step of drying the base polymer particles (step 4) is performed using a horizontal mixer, a rotary kiln, a paddle dryer, or a mobile dryer of a steam tube dryer.
18. The method according to claim 8, wherein the water content of the superabsorbent polymer particles obtained in the step of drying the base polymer particles (step 4) is from 10 to 20% by weight.
19. The method of claim 8, further comprising the step of forming a surface cross-linked layer on at least a portion of the surface of the superabsorbent polymer particles prepared in step 4 in the presence of a surface cross-linking agent.
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| KR10-2022-0140642 | 2022-10-27 | ||
| KR1020220140642A KR20230062423A (en) | 2021-10-29 | 2022-10-27 | Super absorbent polymer composition and preparation method thereof |
| PCT/KR2022/016642 WO2023075482A1 (en) | 2021-10-29 | 2022-10-28 | Super absorbent polymer composition and preparation method thereof |
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