CA2462053C - Starch networks as absorbent or superabsorbent materials and their preparation by extrusion - Google Patents
Starch networks as absorbent or superabsorbent materials and their preparation by extrusion Download PDFInfo
- Publication number
- CA2462053C CA2462053C CA2462053A CA2462053A CA2462053C CA 2462053 C CA2462053 C CA 2462053C CA 2462053 A CA2462053 A CA 2462053A CA 2462053 A CA2462053 A CA 2462053A CA 2462053 C CA2462053 C CA 2462053C
- Authority
- CA
- Canada
- Prior art keywords
- starch
- absorbent
- extrudate
- absorbent material
- group
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229920002472 Starch Polymers 0.000 title claims abstract description 105
- 235000019698 starch Nutrition 0.000 title claims abstract description 103
- 239000008107 starch Substances 0.000 title claims abstract description 92
- 239000002250 absorbent Substances 0.000 title claims abstract description 90
- 230000002745 absorbent Effects 0.000 title claims abstract description 83
- 239000000463 material Substances 0.000 title claims abstract description 68
- 238000001125 extrusion Methods 0.000 title description 30
- 238000002360 preparation method Methods 0.000 title description 9
- 229920000945 Amylopectin Polymers 0.000 claims abstract description 81
- 239000000203 mixture Substances 0.000 claims description 42
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 33
- 238000000034 method Methods 0.000 claims description 29
- 229920001282 polysaccharide Polymers 0.000 claims description 28
- 239000005017 polysaccharide Substances 0.000 claims description 28
- 230000008569 process Effects 0.000 claims description 27
- 150000004804 polysaccharides Chemical class 0.000 claims description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 239000004971 Cross linker Substances 0.000 claims description 14
- 230000032683 aging Effects 0.000 claims description 14
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 13
- 239000003431 cross linking reagent Substances 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 13
- 229920002261 Corn starch Polymers 0.000 claims description 12
- -1 acrylic ester Chemical class 0.000 claims description 12
- UGTZMIPZNRIWHX-UHFFFAOYSA-K sodium trimetaphosphate Chemical compound [Na+].[Na+].[Na+].[O-]P1(=O)OP([O-])(=O)OP([O-])(=O)O1 UGTZMIPZNRIWHX-UHFFFAOYSA-K 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 12
- 235000019759 Maize starch Nutrition 0.000 claims description 10
- 239000003513 alkali Substances 0.000 claims description 10
- 229920000247 superabsorbent polymer Polymers 0.000 claims description 10
- 235000013305 food Nutrition 0.000 claims description 9
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 claims description 7
- 239000000835 fiber Substances 0.000 claims description 7
- 238000000227 grinding Methods 0.000 claims description 7
- 230000014759 maintenance of location Effects 0.000 claims description 7
- XHXFXVLFKHQFAL-UHFFFAOYSA-N phosphoryl trichloride Chemical compound ClP(Cl)(Cl)=O XHXFXVLFKHQFAL-UHFFFAOYSA-N 0.000 claims description 7
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 6
- LEQAOMBKQFMDFZ-UHFFFAOYSA-N glyoxal Chemical compound O=CC=O LEQAOMBKQFMDFZ-UHFFFAOYSA-N 0.000 claims description 6
- 239000011780 sodium chloride Substances 0.000 claims description 6
- 235000019832 sodium triphosphate Nutrition 0.000 claims description 6
- 239000004583 superabsorbent polymers (SAPs) Substances 0.000 claims description 6
- WQZGKKKJIJFFOK-QTVWNMPRSA-N D-mannopyranose Chemical compound OC[C@H]1OC(O)[C@@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-QTVWNMPRSA-N 0.000 claims description 5
- 229920001586 anionic polysaccharide Polymers 0.000 claims description 5
- 150000004836 anionic polysaccharides Chemical class 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 5
- ZIUHHBKFKCYYJD-UHFFFAOYSA-N n,n'-methylenebisacrylamide Chemical compound C=CC(=O)NCNC(=O)C=C ZIUHHBKFKCYYJD-UHFFFAOYSA-N 0.000 claims description 5
- 206010021639 Incontinence Diseases 0.000 claims description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-L Phosphate ion(2-) Chemical compound OP([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-L 0.000 claims description 4
- 229920000297 Rayon Polymers 0.000 claims description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 239000000178 monomer Substances 0.000 claims description 4
- 238000006116 polymerization reaction Methods 0.000 claims description 4
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 claims description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 4
- 150000003839 salts Chemical class 0.000 claims description 4
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 claims description 4
- 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 claims description 3
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 3
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 3
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 claims description 3
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 3
- 229920002678 cellulose Polymers 0.000 claims description 3
- 239000001913 cellulose Substances 0.000 claims description 3
- GYZLOYUZLJXAJU-UHFFFAOYSA-N diglycidyl ether Chemical class C1OC1COCC1CO1 GYZLOYUZLJXAJU-UHFFFAOYSA-N 0.000 claims description 3
- AFOSIXZFDONLBT-UHFFFAOYSA-N divinyl sulfone Chemical compound C=CS(=O)(=O)C=C AFOSIXZFDONLBT-UHFFFAOYSA-N 0.000 claims description 3
- 229940015043 glyoxal Drugs 0.000 claims description 3
- 229920000728 polyester Polymers 0.000 claims description 3
- 229920001223 polyethylene glycol Polymers 0.000 claims description 3
- UVIDMSMLNGZCSV-UHFFFAOYSA-N 2-ethenylguanidine Chemical compound NC(=N)NC=C UVIDMSMLNGZCSV-UHFFFAOYSA-N 0.000 claims description 2
- GJCOSYZMQJWQCA-UHFFFAOYSA-N 9H-xanthene Chemical compound C1=CC=C2CC3=CC=CC=C3OC2=C1 GJCOSYZMQJWQCA-UHFFFAOYSA-N 0.000 claims description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- 244000247812 Amorphophallus rivieri Species 0.000 claims description 2
- 235000001206 Amorphophallus rivieri Nutrition 0.000 claims description 2
- IMROMDMJAWUWLK-UHFFFAOYSA-N Ethenol Chemical compound OC=C IMROMDMJAWUWLK-UHFFFAOYSA-N 0.000 claims description 2
- 229920002907 Guar gum Polymers 0.000 claims description 2
- 240000005979 Hordeum vulgare Species 0.000 claims description 2
- 235000007340 Hordeum vulgare Nutrition 0.000 claims description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 2
- 229920002752 Konjac Polymers 0.000 claims description 2
- CKLJMWTZIZZHCS-REOHCLBHSA-N L-aspartic acid Chemical compound OC(=O)[C@@H](N)CC(O)=O CKLJMWTZIZZHCS-REOHCLBHSA-N 0.000 claims description 2
- 229920000161 Locust bean gum Polymers 0.000 claims description 2
- 240000003183 Manihot esculenta Species 0.000 claims description 2
- 235000016735 Manihot esculenta subsp esculenta Nutrition 0.000 claims description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 2
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims description 2
- 244000134552 Plantago ovata Species 0.000 claims description 2
- 235000003421 Plantago ovata Nutrition 0.000 claims description 2
- 239000004698 Polyethylene Substances 0.000 claims description 2
- 239000004743 Polypropylene Substances 0.000 claims description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 2
- 241001494501 Prosopis <angiosperm> Species 0.000 claims description 2
- 235000001560 Prosopis chilensis Nutrition 0.000 claims description 2
- 235000014460 Prosopis juliflora var juliflora Nutrition 0.000 claims description 2
- 239000009223 Psyllium Substances 0.000 claims description 2
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 claims description 2
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 claims description 2
- 240000006394 Sorghum bicolor Species 0.000 claims description 2
- 235000011684 Sorghum saccharatum Nutrition 0.000 claims description 2
- 241000736285 Sphagnum Species 0.000 claims description 2
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 2
- 229920002486 Waxy potato starch Polymers 0.000 claims description 2
- 150000001252 acrylic acid derivatives Chemical class 0.000 claims description 2
- 239000000908 ammonium hydroxide Substances 0.000 claims description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 2
- 235000003704 aspartic acid Nutrition 0.000 claims description 2
- WPJWIROQQFWMMK-UHFFFAOYSA-L beryllium dihydroxide Chemical compound [Be+2].[OH-].[OH-] WPJWIROQQFWMMK-UHFFFAOYSA-L 0.000 claims description 2
- 229910001865 beryllium hydroxide Inorganic materials 0.000 claims description 2
- OQFSQFPPLPISGP-UHFFFAOYSA-N beta-carboxyaspartic acid Natural products OC(=O)C(N)C(C(O)=O)C(O)=O OQFSQFPPLPISGP-UHFFFAOYSA-N 0.000 claims description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 2
- 239000000920 calcium hydroxide Substances 0.000 claims description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 2
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 claims description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 2
- 229920001525 carrageenan Polymers 0.000 claims description 2
- 235000010418 carrageenan Nutrition 0.000 claims description 2
- 229920002301 cellulose acetate Polymers 0.000 claims description 2
- 239000000284 extract Substances 0.000 claims description 2
- 235000020765 fenugreek extract Nutrition 0.000 claims description 2
- 239000000665 guar gum Substances 0.000 claims description 2
- 235000010417 guar gum Nutrition 0.000 claims description 2
- 229960002154 guar gum Drugs 0.000 claims description 2
- 239000000252 konjac Substances 0.000 claims description 2
- 235000010485 konjac Nutrition 0.000 claims description 2
- 235000010420 locust bean gum Nutrition 0.000 claims description 2
- 239000000711 locust bean gum Substances 0.000 claims description 2
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 2
- 239000000347 magnesium hydroxide Substances 0.000 claims description 2
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 2
- 150000002688 maleic acid derivatives Chemical class 0.000 claims description 2
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 claims description 2
- 150000002734 metacrylic acid derivatives Chemical class 0.000 claims description 2
- 125000005395 methacrylic acid group Chemical group 0.000 claims description 2
- DCUFMVPCXCSVNP-UHFFFAOYSA-N methacrylic anhydride Chemical compound CC(=C)C(=O)OC(=O)C(C)=C DCUFMVPCXCSVNP-UHFFFAOYSA-N 0.000 claims description 2
- 239000001814 pectin Substances 0.000 claims description 2
- 229920001277 pectin Polymers 0.000 claims description 2
- 235000010987 pectin Nutrition 0.000 claims description 2
- 229920000747 poly(lactic acid) Polymers 0.000 claims description 2
- 229920001281 polyalkylene Polymers 0.000 claims description 2
- 229920000573 polyethylene Polymers 0.000 claims description 2
- 229920001155 polypropylene Polymers 0.000 claims description 2
- 239000011591 potassium Substances 0.000 claims description 2
- 229910052700 potassium Inorganic materials 0.000 claims description 2
- 235000011056 potassium acetate Nutrition 0.000 claims description 2
- 239000011736 potassium bicarbonate Substances 0.000 claims description 2
- 235000015497 potassium bicarbonate Nutrition 0.000 claims description 2
- 229910000028 potassium bicarbonate Inorganic materials 0.000 claims description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 2
- 235000011181 potassium carbonates Nutrition 0.000 claims description 2
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims description 2
- 229910000160 potassium phosphate Inorganic materials 0.000 claims description 2
- 235000011009 potassium phosphates Nutrition 0.000 claims description 2
- ARJOQCYCJMAIFR-UHFFFAOYSA-N prop-2-enoyl prop-2-enoate Chemical compound C=CC(=O)OC(=O)C=C ARJOQCYCJMAIFR-UHFFFAOYSA-N 0.000 claims description 2
- 229940070687 psyllium Drugs 0.000 claims description 2
- 239000002964 rayon Substances 0.000 claims description 2
- 229940100486 rice starch Drugs 0.000 claims description 2
- 239000011734 sodium Substances 0.000 claims description 2
- 229910052708 sodium Inorganic materials 0.000 claims description 2
- 235000015424 sodium Nutrition 0.000 claims description 2
- 239000001632 sodium acetate Substances 0.000 claims description 2
- 235000017281 sodium acetate Nutrition 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- 235000017550 sodium carbonate Nutrition 0.000 claims description 2
- 239000001488 sodium phosphate Substances 0.000 claims description 2
- 229910000162 sodium phosphate Inorganic materials 0.000 claims description 2
- 235000011008 sodium phosphates Nutrition 0.000 claims description 2
- 239000000213 tara gum Substances 0.000 claims description 2
- 235000010491 tara gum Nutrition 0.000 claims description 2
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims description 2
- 229940100445 wheat starch Drugs 0.000 claims description 2
- 229920001285 xanthan gum Polymers 0.000 claims description 2
- XENVCRGQTABGKY-ZHACJKMWSA-N chlorohydrin Chemical compound CC#CC#CC#CC#C\C=C\C(Cl)CO XENVCRGQTABGKY-ZHACJKMWSA-N 0.000 claims 2
- GDTRAYDPXKZJGD-UHFFFAOYSA-N dichlorophosphoryl hypochlorite Chemical compound ClOP(Cl)(Cl)=O GDTRAYDPXKZJGD-UHFFFAOYSA-N 0.000 claims 2
- GKIPXFAANLTWBM-UHFFFAOYSA-N epibromohydrin Chemical compound BrCC1CO1 GKIPXFAANLTWBM-UHFFFAOYSA-N 0.000 claims 2
- 229920000433 Lyocell Polymers 0.000 claims 1
- 239000004677 Nylon Substances 0.000 claims 1
- 125000000129 anionic group Chemical group 0.000 claims 1
- 229920001778 nylon Polymers 0.000 claims 1
- FAIAAWCVCHQXDN-UHFFFAOYSA-N phosphorus trichloride Chemical compound ClP(Cl)Cl FAIAAWCVCHQXDN-UHFFFAOYSA-N 0.000 claims 1
- 230000000694 effects Effects 0.000 description 13
- 238000010521 absorption reaction Methods 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 8
- 101000628535 Homo sapiens Metalloreductase STEAP2 Proteins 0.000 description 7
- 102100026711 Metalloreductase STEAP2 Human genes 0.000 description 7
- 238000013461 design Methods 0.000 description 7
- 238000005259 measurement Methods 0.000 description 7
- 229920000642 polymer Polymers 0.000 description 7
- 229920000856 Amylose Polymers 0.000 description 6
- 230000015556 catabolic process Effects 0.000 description 5
- 238000006731 degradation reaction Methods 0.000 description 5
- 239000011236 particulate material Substances 0.000 description 5
- 229920000058 polyacrylate Polymers 0.000 description 5
- 238000010998 test method Methods 0.000 description 5
- 229910019142 PO4 Inorganic materials 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 235000021317 phosphate Nutrition 0.000 description 4
- 238000005086 pumping Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000008961 swelling Effects 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- 230000000739 chaotic effect Effects 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 230000000774 hypoallergenic effect Effects 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- 239000010452 phosphate Substances 0.000 description 3
- 108010067930 structure-specific endonuclease I Proteins 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 150000003926 acrylamides Chemical class 0.000 description 2
- 150000001253 acrylic acids Chemical class 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 125000002091 cationic group Chemical group 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000003086 colorant Substances 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000003750 conditioning effect Effects 0.000 description 2
- 239000008120 corn starch Substances 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000005755 formation reaction Methods 0.000 description 2
- 239000000499 gel Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000003898 horticulture Methods 0.000 description 2
- 239000003906 humectant Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 238000010526 radical polymerization reaction Methods 0.000 description 2
- 235000014102 seafood Nutrition 0.000 description 2
- 239000003566 sealing material Substances 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 229920001059 synthetic polymer Polymers 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 description 1
- 241001660687 Xantho Species 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 230000002009 allergenic effect Effects 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 239000013060 biological fluid Substances 0.000 description 1
- JMSRBKPMLUGHCR-UHFFFAOYSA-N bromohydrin Chemical compound BrC[C]1CO1 JMSRBKPMLUGHCR-UHFFFAOYSA-N 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 235000012438 extruded product Nutrition 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000007306 functionalization reaction Methods 0.000 description 1
- 229920000578 graft copolymer Polymers 0.000 description 1
- 238000010559 graft polymerization reaction Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 229920006158 high molecular weight polymer Polymers 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229920001206 natural gum Polymers 0.000 description 1
- 238000006053 organic reaction Methods 0.000 description 1
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- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B35/00—Preparation of derivatives of amylopectin
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
- A61L15/28—Polysaccharides or their derivatives
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/42—Use of materials characterised by their function or physical properties
- A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents
-
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Abstract
The present invention relates an absorbent material consisting of a molecular network of starch molecules, the starch molecules comprising an amylopectin content of at least 90% (w/w). The molecular network can either be comprised of self-entangled starches or cross-linked starches.
Description
TITLE OF THE INVENTION
STARCH NETWORKS AS ABSORBENT OR SUPERABSORBENT
MATERIALS AND THEIR PREPARATION BY EXTRUSION
FIELD OF THE INVENTION
The present invention relates to starch networks as absorbent or superabsorbent materials as well as to the preparation of these starch networks by extrusion.
BACKGROUND OF THE INVENTION
Superabsorbent polymers are primarily used as absorbents for biological fluids, water and aqueous solutions. Water absorbent materials such as superabsorbent polymers can be employed in various applications, such as in disposable sanitary products (i.e. diapers, incontinence articles, female hygiene products, and absorbent dressings), household articles, sealing materials, humectants (i.e.
agricultural products for soil conditioning), anti-condensation coatings, water-storing materials (agriculture/horticulture), absorbent paper products, surgical absorbents, pet litter, bandages, wound dressings and as chemical absorbents. Furthermore, they can also be employed in applications related to the transportation of fresh food or seafood, as well as in food packaging applications.
Polyacrylates, obtained from the polymerization of monomers such as acrylic acids and acrylamides (non-renewable sources), constitute a major portion of the commercially available superabsorbents (Modern Superabsorbent Polymer Technology, Buchholz F.L. and Graham A.T. Eds., Wiley-VCH, New York, 1998). However, their biodegradability is questionable, especially for high molecular weight polymers.
Polyacrylates generally contain small amounts of residual monomeric starting materials (i.e.
acrylic acids and acrylamides) possessing both toxic and allergenic potential.
Superabsorbent polysaccharide-based grafted-polymers are obtained via the grafting of an unsaturated monomer (acrylonitrile, acrylic acid, acrylamide) onto starch, or, less frequently, cellulose. The so-obtained polymers, also called "Super Slurper", have shown a water absorption ranging from 700 to 5300 g/g in deionised water, and up to 140 g/g in a 0.9 % saline solution (Riccardo P.O., Water-Absorbent Polymers:
A Patent Survey. J. Macromol. Sci., Rev. Macromol. Chem. Phys., 1994, 607-662 and references cited therein). Despite their very high water absorption capability, the grafted polysaccharides, prepared by radical polymerization, are not known to be biodegradable or hypoallergenic, nor are they prepared from renewable sources.
Polyaspartates have also been described to offer good absorbing properties (Ross et al. US 5,612,384). However, polyaspartates appear to possess several drawbacks regarding their low molecular weight. Moreover, polyaspartates are prepared from non-renewable sources which constitutes an additional drawback (Koskan et aL US
5,221,733). Furthermore, these polymers are strongly ionic and are thus subject to performance fluctuations in saline solutions.
Carboxymethylcellulose (CMC), and carboxymethylstarch (CMS) (Modern Superabsorbent Polymer Technology, Buchholz F.L. and Graham A.T. ed., Wiley-VCH, Toronto, 1998, 239-241; Gross et al. US 5,079,354; Arno at al. US
4,117,222;
Thornton at al. PCT WO 00/35504; Mindt eta!. GB 1576475; Couture at al. CA
2,362,006;
Annergren et al. PCT WO 00/21581) constitute other known polysaccharide-based superabsorbents. Cost has always been an issue with these superabsorbents, and they can therefore not be used alone in order to compete with the synthetic polymers. Moreover, these polymers are strongly ionic, as is the case for polyacrylates and polyaspartates, rendering them subject to performance fluctuations in saline solutions.
Nonetheless, these products can be used in synergistic formulations, leading to cost effective superabsorbent materials (Bergeron CA 2,426,478; Richman et a!. US 4,454,055).
Natural polysaccharide-based superabsorbents constitute a very attractive class of polymers, considering that they can be biodegradable and hypoallergenic, in addition to the fact that they are made from renewable sources such as starch. Polysaccharides have been previously used in an extrusion process for the preparation of non-crosslinked starch-based materials as absorbents for liquids (Hupp6 et al. CA 2,308,537).
The use of extruders as continuous reactors for processes such as polymerization, polymer modification or compatibilization of polymer blends, involves technologies that are gaining in popularity. These technologies are competing with conventional operations with respect to environmental considerations, efficiency and economic operators. In the case of reactive extrusion, several organic reactions can be conducted in extruders, including polymerization, grafting, copolymer formation, molecular network formation, crosslinking, functionalization and controlled degradation (Reactive Extrusion: Principles and Practice, Xanthos M. Ed., Hanser Publishers, New York, 1992).
This technology has been largely applied in the preparation of polysaccharide-based products from renewable sources such as cross-linked starches, and in applications such as food texturing products (Salay E. et al., Starch/Staerke, 1990, 42, 15-17;
Nabeshima E.
H. et al., Carbohydr. Polym., 2001, 45, 347-353; Narkrugsa W. et al., Starch/Staerke, 1992, 44, 81-90; Chang Y.-H at at. J. Food Sci., 1992, 57, 203-205; Kim C.-T. et at, Starch/Staerke, 1999, 51, 280-286). However, none of the products cited are absorbent or superabsorbent materials.
Cross-linked starches have been exhaustively studied (Kulicke W.M.
et al. Starch/Starke, 41, 1989, 140-146; Brine et al. PCT WO 01 /19404A1;
Ameye at at US
App. 2003/0143277; Seib at al. WO 99/64508; Dumoulin et al. PCT WO 98/35992).
However, these cross-linked starches (gels) are not absorbent or superabsorbent materials.
Glass-like polysaccharide abrasive grits have been prepared by extrusion processes of native or crosslinked starches (Lane at al. US
5,367,068). An extrusion process for the preparation of a natural gum substitute composed of cross-linked starch, using phosphorous oxychloride, has been disclosed (Hauber et at PCT WO
97/00620). However, these products are once again not absorbent or superabsorbent materials.
The preparation of absorbent materials consisting of crosslinked starch using trisodium trimetaphosphate in a co-continuous water-oil system has been described (Feil et at EP 0900807). In order to remove the oil and to recover the starch-phosphate derivative, an organic solvent such as cyclohexane was added, followed by washing with ethanol. The use of oils and organic solvents are important drawbacks of this batch process. They dramatically increase the production cost of this absorbent, while simultaneously complicating the process.
There thus remains a need for new polysaccharide-based absorbent or superabsorbent materials that are non-abrasive, hypoallergenic, and biodegradable, and which can be cost-efficiently produced from renewable natural sources.
The present invention seeks to meet these and other needs.
STARCH NETWORKS AS ABSORBENT OR SUPERABSORBENT
MATERIALS AND THEIR PREPARATION BY EXTRUSION
FIELD OF THE INVENTION
The present invention relates to starch networks as absorbent or superabsorbent materials as well as to the preparation of these starch networks by extrusion.
BACKGROUND OF THE INVENTION
Superabsorbent polymers are primarily used as absorbents for biological fluids, water and aqueous solutions. Water absorbent materials such as superabsorbent polymers can be employed in various applications, such as in disposable sanitary products (i.e. diapers, incontinence articles, female hygiene products, and absorbent dressings), household articles, sealing materials, humectants (i.e.
agricultural products for soil conditioning), anti-condensation coatings, water-storing materials (agriculture/horticulture), absorbent paper products, surgical absorbents, pet litter, bandages, wound dressings and as chemical absorbents. Furthermore, they can also be employed in applications related to the transportation of fresh food or seafood, as well as in food packaging applications.
Polyacrylates, obtained from the polymerization of monomers such as acrylic acids and acrylamides (non-renewable sources), constitute a major portion of the commercially available superabsorbents (Modern Superabsorbent Polymer Technology, Buchholz F.L. and Graham A.T. Eds., Wiley-VCH, New York, 1998). However, their biodegradability is questionable, especially for high molecular weight polymers.
Polyacrylates generally contain small amounts of residual monomeric starting materials (i.e.
acrylic acids and acrylamides) possessing both toxic and allergenic potential.
Superabsorbent polysaccharide-based grafted-polymers are obtained via the grafting of an unsaturated monomer (acrylonitrile, acrylic acid, acrylamide) onto starch, or, less frequently, cellulose. The so-obtained polymers, also called "Super Slurper", have shown a water absorption ranging from 700 to 5300 g/g in deionised water, and up to 140 g/g in a 0.9 % saline solution (Riccardo P.O., Water-Absorbent Polymers:
A Patent Survey. J. Macromol. Sci., Rev. Macromol. Chem. Phys., 1994, 607-662 and references cited therein). Despite their very high water absorption capability, the grafted polysaccharides, prepared by radical polymerization, are not known to be biodegradable or hypoallergenic, nor are they prepared from renewable sources.
Polyaspartates have also been described to offer good absorbing properties (Ross et al. US 5,612,384). However, polyaspartates appear to possess several drawbacks regarding their low molecular weight. Moreover, polyaspartates are prepared from non-renewable sources which constitutes an additional drawback (Koskan et aL US
5,221,733). Furthermore, these polymers are strongly ionic and are thus subject to performance fluctuations in saline solutions.
Carboxymethylcellulose (CMC), and carboxymethylstarch (CMS) (Modern Superabsorbent Polymer Technology, Buchholz F.L. and Graham A.T. ed., Wiley-VCH, Toronto, 1998, 239-241; Gross et al. US 5,079,354; Arno at al. US
4,117,222;
Thornton at al. PCT WO 00/35504; Mindt eta!. GB 1576475; Couture at al. CA
2,362,006;
Annergren et al. PCT WO 00/21581) constitute other known polysaccharide-based superabsorbents. Cost has always been an issue with these superabsorbents, and they can therefore not be used alone in order to compete with the synthetic polymers. Moreover, these polymers are strongly ionic, as is the case for polyacrylates and polyaspartates, rendering them subject to performance fluctuations in saline solutions.
Nonetheless, these products can be used in synergistic formulations, leading to cost effective superabsorbent materials (Bergeron CA 2,426,478; Richman et a!. US 4,454,055).
Natural polysaccharide-based superabsorbents constitute a very attractive class of polymers, considering that they can be biodegradable and hypoallergenic, in addition to the fact that they are made from renewable sources such as starch. Polysaccharides have been previously used in an extrusion process for the preparation of non-crosslinked starch-based materials as absorbents for liquids (Hupp6 et al. CA 2,308,537).
The use of extruders as continuous reactors for processes such as polymerization, polymer modification or compatibilization of polymer blends, involves technologies that are gaining in popularity. These technologies are competing with conventional operations with respect to environmental considerations, efficiency and economic operators. In the case of reactive extrusion, several organic reactions can be conducted in extruders, including polymerization, grafting, copolymer formation, molecular network formation, crosslinking, functionalization and controlled degradation (Reactive Extrusion: Principles and Practice, Xanthos M. Ed., Hanser Publishers, New York, 1992).
This technology has been largely applied in the preparation of polysaccharide-based products from renewable sources such as cross-linked starches, and in applications such as food texturing products (Salay E. et al., Starch/Staerke, 1990, 42, 15-17;
Nabeshima E.
H. et al., Carbohydr. Polym., 2001, 45, 347-353; Narkrugsa W. et al., Starch/Staerke, 1992, 44, 81-90; Chang Y.-H at at. J. Food Sci., 1992, 57, 203-205; Kim C.-T. et at, Starch/Staerke, 1999, 51, 280-286). However, none of the products cited are absorbent or superabsorbent materials.
Cross-linked starches have been exhaustively studied (Kulicke W.M.
et al. Starch/Starke, 41, 1989, 140-146; Brine et al. PCT WO 01 /19404A1;
Ameye at at US
App. 2003/0143277; Seib at al. WO 99/64508; Dumoulin et al. PCT WO 98/35992).
However, these cross-linked starches (gels) are not absorbent or superabsorbent materials.
Glass-like polysaccharide abrasive grits have been prepared by extrusion processes of native or crosslinked starches (Lane at al. US
5,367,068). An extrusion process for the preparation of a natural gum substitute composed of cross-linked starch, using phosphorous oxychloride, has been disclosed (Hauber et at PCT WO
97/00620). However, these products are once again not absorbent or superabsorbent materials.
The preparation of absorbent materials consisting of crosslinked starch using trisodium trimetaphosphate in a co-continuous water-oil system has been described (Feil et at EP 0900807). In order to remove the oil and to recover the starch-phosphate derivative, an organic solvent such as cyclohexane was added, followed by washing with ethanol. The use of oils and organic solvents are important drawbacks of this batch process. They dramatically increase the production cost of this absorbent, while simultaneously complicating the process.
There thus remains a need for new polysaccharide-based absorbent or superabsorbent materials that are non-abrasive, hypoallergenic, and biodegradable, and which can be cost-efficiently produced from renewable natural sources.
The present invention seeks to meet these and other needs.
SUMMARY OF THE INVENTION
The present invention relates to a starch-based absorbent or superabsorbent material, wherein the starch-based material comprises an amylopectin content of at least 90% (weight/weight, referred to hereinafter as w/w). More specifically, the present invention relates to an absorbent or superabsorbent material consisting of a molecular network of starch molecules, the starch molecules comprising at least 90% (w/w) amylopectin. The molecular network of starch molecules can be composed of either self-entangled starch molecules, or cross-linked starch molecules.
The present invention also relates to an absorbent or superabsorbent material comprising a molecular network of starch molecules, wherein the material is preferably a particulate material.
In a first preferred embodiment, the present invention relates to a particulate absorbent or superabsorbent material comprising a molecular network of starch molecules, wherein the material has a centrifuge retention capacity (CRC) of at least 10 g/g and a free swell capacity (FSC) of at least 13 g/g.
Furthermore, the present invention relates to a process for preparing a starch-based absorbent or superabsorbent material, wherein the starch-based material comprises an amylopectin content of at least 90% (weight/weight, referred to hereinafter as w/w). More specifically, the present invention relates to a process for preparing an absorbent or superabsorbent material consisting of a molecular network of starch molecules, the starch molecules comprising at least 90% (w/w) amylopectin. In one particular embodiment, the process involves the steps of mixing a starch comprising at least 90% amylopectin with water to produce a paste; feeding the paste into an extruder to produce an extrudate; aging the extrudate; and grinding the extrudate. In a further particular embodiment, the process involves the steps of mixing a starch comprising at least 90% amylopectin with water, an alkali and a cross-linking agent to produce a paste;
feeding the based paste into an extruder to produce an extrudate; aging the extrudate ; and grinding the extrudate.
In a second preferred embodiment, the present invention relates to an extrusion process for preparing a particulate absorbent or superabsorbent material comprising a molecular network of starch molecules.
Finally, the present invention relates to an absorbent or superabsorbent mixture comprising a first absorbent or superabsorbent material consisting of a molecular network of starch molecules, the starch molecules comprising at least 90%
(w/w) amylopectin, and a second co-absorbent component selected from the group of 5 synthetic polymers, mannose containing polysaccharides, ionic polysaccharides, and natural or synthetic fibers.
Further scope and applicability will become apparent from the detailed description given hereinafter. It should be understood however, that this detailed description, while indication preferred embodiments of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.
BRIEF DESCRIPTION OF DRAWINGS
Having thus generally described the invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof, and wherein:
Figure 1 illustrates a general diagram of an extruder (1) including a die plate (2). In the case of a single screw extruder (SSE), the barrel comprises heating sections (Tbl, Tb2, Tb3, and Td); in the case of a twin screw extruder (TSE), the barrel comprises heating sections (Tbl, Tb2, Tb3, Tb4, Tb5, Tb6, Tb7, Tb8, and Td).
Figure 2 illustrates various parameters (h1: feeding section flight depth; h2: pumping section flight depth; 11: feeding section length; 12:
pumping section length; Itot: total screw length; e: flight width; and b: screw pitch) involved in the screw design of SSEs.
Figure 3 illustrates an embodiment of the die geometry as used with SSEI (described in table 1). In this embodiment, the die opening diameter (3) was 8.5 mm;
the total die length (4) was 111 mm; the length of the barrel diameter opening (5) was 6.4 mm; the extruder barrel diameter (6) was 44.5 mm; and the conical transition angles (7) were both 300.
Figure 4 illustrates an embodiment of the die geometry and valve plate cross-section as used for single screw extruder 2 (SSE2). The die is divided into an opening plate (11), a valve plate (12) and a coupling plate (13) and includes a valve (14) for flow rate adjustments. In this embodiment, the die opening diameter (3) was 8.5 mm; the total die length comprises the length of the opening plate (8) (64 mm), the length of the valve plate (9) (25.4 mm), and the length of the coupling plate (10) (42 mm); the length of the barrel diameter opening (5) was 6.4 mm; the extruder barrel diameter (6) was 44.5 mm; the conical transition angles (7) were both 300; and the inner diameter (15) of the valve plate (9) was 25.4 mm.
Figure 5 illustrates an embodiment of a twin lead feed screw element as used in the TSE. In this embodiment, the twin lead feed screw pitch (16) was 50.8 mm; the flight width (17) was 1.5 mm; and the inner (18) and outer (19) diameters were 27.7 and 48.9 mm respectively.
Figure 6 illustrates an embodiment of a single lead screw element as used in the TSE. In this embodiment, the single lead screw pitch (21) was 12.7 mm; the flight width (22) was 2.7 mm; the inner (18) and outer (20) diameters were 27.7 and 38.3 mm respectively.
Figure 7 illustrates an embodiment of a paddle block (25) as used in the TSE, and including seven single block elements having a forward staggering angle of 30 . In this embodiment, a single paddle block element (24) had a width (23) of 12.7 mm; the inner (18) and outer (19) diameters were 27.7 and 48.9 mm respectively.
Figure 8 illustrates an embodiment of the die geometry as well as the die cross-section (29) (along line A-A) as used in the TSE. In this embodiment, the die had two openings (26) of 6 mm respectively; the spacing (28) between the die openings was 30 mm; the uttermost spacing (27) between the screw barrels was mm; the barrel diameter (30) was 50 mm; the length of the cylindrical portion of the die (33) was 38 mm and its diameter (31) 30 mm; the length of the conical transition (34) from the cylindrical portion to the die opening was 20 mm; and the total extrudate volume (32) of the die was 250 cm3.
DETAILED DESCRIPTION OF THE INVENTION
Definitions and abbreviations (symbols and units):
The term "Free Swell Capacity" (FSC), also called absorption, is expressed in grams (g) of substance absorbed (0.9% NaCl solution) per gram (g) of dry sample.
The term "Centrifuge Retention Capacity" (CRC), also called retention, is expressed in grams (g) of substance absorbed (0.9% NaCl solution) per gram (g) of dry sample.
The term "Residence Time" refers to the time taken by the material to get trough the extruder, from the feed port to the die. The residence time is measured by adding a small quantity of material containing a coloring agent into the feed port. The chronometer is started when the colorant enters the barrel and is stopped when coloration is observed at the die exit.
The term "Extrudate Temperature" refers to the temperature of the material at the die exit as measured by a portable thermocouple plunged into one of the die openings.
The term "starch" is understood as being composed of two polysaccharides; amylose and amylopectin. Amylose is a linear polysaccharide having an average molecular weight of about 250,000 g/mol. Amylopectin is a branched polysaccharide (branching via 1,6-a-glucosidic links) having an average molecular weight of about 75,000,000 g/mol ("Starch: Chemistry and Technology", Whistler R.L., Bemiller J.N. and Paschall E.F. Eds., Academic Press, Orlando, 1984, page 287). In plants, amylopectin is stocked in starch granules in a semi-crystalline form. When heated in the presence of water, starch gelatinizes. Its semi-crystalline structure will change to an amorphous, chaotic state.
T: Extrudate temperature ( C); 0: Screw rotational speed, expressed in RPM (revolutions per minute); Q: Extruder throughput (Kg/h); QdN: Die extrusion throughput (Kg/h) (Figure 4); Tbx: Temperature ( C) of barrel section X
(Figure 1); Td: Die temperature ( C) (Figure 1); HP: Motor power of extruder (Horse Power); Db:
Extruder barrel diameter (mm) (Figure 1); hi: Feeding section flight depth (mm) (Figure 2); h2:
Pumping section flight depth (mm) (Figure 2); Itot: Total screw length (mm) (Figure 2);11:
Feeding section length (mm) (Figure 2); 12: Pumping section length (mm) Figure 2); b:
Screw pitch (mm) (Figure 2); and e: Flight width (mm) (Figure 2).
In a broad sense, the present invention relates to a starch-based absorbent or superabsorbent material, wherein the starch-based material is essentially composed of a molecular network of amylopectin molecules consisting of either self-entangled amylopectin molecules, cross-linked amylopectin molecules or a mixture of both self-entangled amylopectin molecules and cross-linked amylopectin molecules.
It was previously illustrated by Huppt at a!. (CA 2,308,537) that it is possible to produce a starch-based absorbent having low absorption performances (reported to be 7.5 g/g in 0.9 % NaCl solution) by extrusion. As disclosed hereinafter, it was unexpectedly discovered that the absorption performances of this extruded starch-based material can be significantly improved by increasing the amylopectin content to values in excess of 90% (w/w).
Starch-based absorbent or superabsorbent materials having a CRC
of at least 10 g/g and a FSC of at least 13 g/g, are preferred. It was discovered that such starch-based absorbent or superabsorbent materials can be obtained when comprising a molecular network of amylopectin molecules and wherein the amylopectin content is in excess of 90% (w/w). The molecular network of amylopectin molecules should be consisting of either self-entangled amylopectin molecules or cross-linked amylopectin molecules, both of which can be produced using an extrusion process. In cases wherein the extrudate consists of cross-linked amylopectin molecules, the absorbent or superabsorbent material is obtained by cross-linking, aging and grinding the extrudate.
Self-entangled starches can be produced by an extrusion process using a specific flow-die configuration, aging and grinding the extrudate. It was discovered that the desired molecular network of amylopectin molecules can be obtained by extruding amylopectin with different cross-linkers, under alkaline conditions. Non-limiting examples of such cross-linkers include sodium trimetaphosphate, sodium tripolyphosphate, phosphorous oxychloride, epichlorohydrin, divinyl sulfone, chiorohydrin, bromohydrin, N,N'-methylenebisacrylamide, alkylenebisacrylamides, ethylene glycol diglycidyl ether, diepoxyalkanes, diglycidyl ethers, glyoxal, glutaraldehyde, dialdehydes, diactivated polyethylene glycols (Couture at a!. CA 2,362,006), and mixture thereof.
Examples 1 to 16 (Table 3) illustrate the effect of different extruded amylopectin/amylose blends on the FSC and CRC. The blends were obtained with a single screw extruder using a die (8.5mm diameter) at about 140 C. These blends produced have an amylopectin content ranging from 72% (levels observed in common corn starch) to 99%
(levels observed in pure waxy com starch). The moisture content of all blends was adjusted to about 30%. The results illustrate that blends having an amylopectin content of at least 90% (w/w) and produced using lower die flow rates (Q) provide for optimal performances.
Typical starches possessing the required amylopectin content (90% w/w) are waxy starches. Waxy starches can be selected from the group consisting of waxy maize starch, waxy wheat starch, waxy rice starch, waxy sorghum starch, waxy potato starch, waxy cassava starch, waxy barley starch and mixtures thereof. A
preferred waxy starch is waxy maize starch.
Examples 17 and 18 (Table 4) show two amylopectin extrudates, both produced using an identical extruder throughput "Q", but using a different die extrusion throughput "Qdie". As illustrated in Figure 4, the die throughput (flow rate) is valve-controlled. As can be observed from the experimental results, the use of a lower Qd1e value provides for an extrudate having significantly better FSC and CRC.
The molecular network of cross-linked amylopectin molecules is preferably produced using phosphates cross-linkers since these agents are very well suited to be used in extrusion processes, in addition to being biodegradable.
Preferred phosphate cross-linking agents are sodium trimetaphosphate, sodium tripolyphosphate and phosphorous oxychloride. These cross-linkers produce biodegradable phosphate diester linkages. A more preferred phosphate cross-linking agent is sodium trimetaphosphate.
It was discovered that concentrations of cross-linkers ranging from 0.001 to 2.0 % (w/w on a dry starch basis without added moisture) provide for molecular networks of cross-linked amylopectin molecules having good FSC and CRC performances. In order to achieve efficient cross-linking, the cross-linkers should be mixed with a small amount of alkali. Typical concentrations of alkali range from 0.001 to 2.0 % (w/w on a dry starch basis). Typical paste compositions should comprise a water content ranging from 25% to 45% (w/w), an alkali content ranging from 0.001 to 2.0 % (w/w on a dry starch basis), a cross-linking agent content ranging from 0.001 to 2.0 % (w/w on a dry starch basis), the balance being a starch comprising an amylopectin content of at least 90 %
(w/w).
Non-limiting examples of alkalis include sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, beryllium hydroxide, ammonium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium acetate, potassium acetate, sodium phosphate, sodium hydrogenophosphate, potassium phosphate, potassium hydrogenophosphate and mixture thereof. A preferred alkali is sodium hydroxide.
Examples 19-25 (Table 5) illustrate various amylopectin extrudates produced with different cross-linking agents (also referred too as C-linker) in a twin screw 5 extruder (die diameter of 6 mm) having a moisture content of 30%0. As can be observed from the experimental results, the use of cross-linkers results in amylopectin extrudates having significantly better FSC and CRC performances. As can be concluded from the results shown in Table 5, the FSC and CRC performances can be optimized using specific amounts of a given cross-linker and NaOH (Examples 20, 23 and 25).
The present invention relates to a starch-based absorbent or superabsorbent material, wherein the starch-based material comprises an amylopectin content of at least 90% (weight/weight, referred to hereinafter as w/w). More specifically, the present invention relates to an absorbent or superabsorbent material consisting of a molecular network of starch molecules, the starch molecules comprising at least 90% (w/w) amylopectin. The molecular network of starch molecules can be composed of either self-entangled starch molecules, or cross-linked starch molecules.
The present invention also relates to an absorbent or superabsorbent material comprising a molecular network of starch molecules, wherein the material is preferably a particulate material.
In a first preferred embodiment, the present invention relates to a particulate absorbent or superabsorbent material comprising a molecular network of starch molecules, wherein the material has a centrifuge retention capacity (CRC) of at least 10 g/g and a free swell capacity (FSC) of at least 13 g/g.
Furthermore, the present invention relates to a process for preparing a starch-based absorbent or superabsorbent material, wherein the starch-based material comprises an amylopectin content of at least 90% (weight/weight, referred to hereinafter as w/w). More specifically, the present invention relates to a process for preparing an absorbent or superabsorbent material consisting of a molecular network of starch molecules, the starch molecules comprising at least 90% (w/w) amylopectin. In one particular embodiment, the process involves the steps of mixing a starch comprising at least 90% amylopectin with water to produce a paste; feeding the paste into an extruder to produce an extrudate; aging the extrudate; and grinding the extrudate. In a further particular embodiment, the process involves the steps of mixing a starch comprising at least 90% amylopectin with water, an alkali and a cross-linking agent to produce a paste;
feeding the based paste into an extruder to produce an extrudate; aging the extrudate ; and grinding the extrudate.
In a second preferred embodiment, the present invention relates to an extrusion process for preparing a particulate absorbent or superabsorbent material comprising a molecular network of starch molecules.
Finally, the present invention relates to an absorbent or superabsorbent mixture comprising a first absorbent or superabsorbent material consisting of a molecular network of starch molecules, the starch molecules comprising at least 90%
(w/w) amylopectin, and a second co-absorbent component selected from the group of 5 synthetic polymers, mannose containing polysaccharides, ionic polysaccharides, and natural or synthetic fibers.
Further scope and applicability will become apparent from the detailed description given hereinafter. It should be understood however, that this detailed description, while indication preferred embodiments of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.
BRIEF DESCRIPTION OF DRAWINGS
Having thus generally described the invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof, and wherein:
Figure 1 illustrates a general diagram of an extruder (1) including a die plate (2). In the case of a single screw extruder (SSE), the barrel comprises heating sections (Tbl, Tb2, Tb3, and Td); in the case of a twin screw extruder (TSE), the barrel comprises heating sections (Tbl, Tb2, Tb3, Tb4, Tb5, Tb6, Tb7, Tb8, and Td).
Figure 2 illustrates various parameters (h1: feeding section flight depth; h2: pumping section flight depth; 11: feeding section length; 12:
pumping section length; Itot: total screw length; e: flight width; and b: screw pitch) involved in the screw design of SSEs.
Figure 3 illustrates an embodiment of the die geometry as used with SSEI (described in table 1). In this embodiment, the die opening diameter (3) was 8.5 mm;
the total die length (4) was 111 mm; the length of the barrel diameter opening (5) was 6.4 mm; the extruder barrel diameter (6) was 44.5 mm; and the conical transition angles (7) were both 300.
Figure 4 illustrates an embodiment of the die geometry and valve plate cross-section as used for single screw extruder 2 (SSE2). The die is divided into an opening plate (11), a valve plate (12) and a coupling plate (13) and includes a valve (14) for flow rate adjustments. In this embodiment, the die opening diameter (3) was 8.5 mm; the total die length comprises the length of the opening plate (8) (64 mm), the length of the valve plate (9) (25.4 mm), and the length of the coupling plate (10) (42 mm); the length of the barrel diameter opening (5) was 6.4 mm; the extruder barrel diameter (6) was 44.5 mm; the conical transition angles (7) were both 300; and the inner diameter (15) of the valve plate (9) was 25.4 mm.
Figure 5 illustrates an embodiment of a twin lead feed screw element as used in the TSE. In this embodiment, the twin lead feed screw pitch (16) was 50.8 mm; the flight width (17) was 1.5 mm; and the inner (18) and outer (19) diameters were 27.7 and 48.9 mm respectively.
Figure 6 illustrates an embodiment of a single lead screw element as used in the TSE. In this embodiment, the single lead screw pitch (21) was 12.7 mm; the flight width (22) was 2.7 mm; the inner (18) and outer (20) diameters were 27.7 and 38.3 mm respectively.
Figure 7 illustrates an embodiment of a paddle block (25) as used in the TSE, and including seven single block elements having a forward staggering angle of 30 . In this embodiment, a single paddle block element (24) had a width (23) of 12.7 mm; the inner (18) and outer (19) diameters were 27.7 and 48.9 mm respectively.
Figure 8 illustrates an embodiment of the die geometry as well as the die cross-section (29) (along line A-A) as used in the TSE. In this embodiment, the die had two openings (26) of 6 mm respectively; the spacing (28) between the die openings was 30 mm; the uttermost spacing (27) between the screw barrels was mm; the barrel diameter (30) was 50 mm; the length of the cylindrical portion of the die (33) was 38 mm and its diameter (31) 30 mm; the length of the conical transition (34) from the cylindrical portion to the die opening was 20 mm; and the total extrudate volume (32) of the die was 250 cm3.
DETAILED DESCRIPTION OF THE INVENTION
Definitions and abbreviations (symbols and units):
The term "Free Swell Capacity" (FSC), also called absorption, is expressed in grams (g) of substance absorbed (0.9% NaCl solution) per gram (g) of dry sample.
The term "Centrifuge Retention Capacity" (CRC), also called retention, is expressed in grams (g) of substance absorbed (0.9% NaCl solution) per gram (g) of dry sample.
The term "Residence Time" refers to the time taken by the material to get trough the extruder, from the feed port to the die. The residence time is measured by adding a small quantity of material containing a coloring agent into the feed port. The chronometer is started when the colorant enters the barrel and is stopped when coloration is observed at the die exit.
The term "Extrudate Temperature" refers to the temperature of the material at the die exit as measured by a portable thermocouple plunged into one of the die openings.
The term "starch" is understood as being composed of two polysaccharides; amylose and amylopectin. Amylose is a linear polysaccharide having an average molecular weight of about 250,000 g/mol. Amylopectin is a branched polysaccharide (branching via 1,6-a-glucosidic links) having an average molecular weight of about 75,000,000 g/mol ("Starch: Chemistry and Technology", Whistler R.L., Bemiller J.N. and Paschall E.F. Eds., Academic Press, Orlando, 1984, page 287). In plants, amylopectin is stocked in starch granules in a semi-crystalline form. When heated in the presence of water, starch gelatinizes. Its semi-crystalline structure will change to an amorphous, chaotic state.
T: Extrudate temperature ( C); 0: Screw rotational speed, expressed in RPM (revolutions per minute); Q: Extruder throughput (Kg/h); QdN: Die extrusion throughput (Kg/h) (Figure 4); Tbx: Temperature ( C) of barrel section X
(Figure 1); Td: Die temperature ( C) (Figure 1); HP: Motor power of extruder (Horse Power); Db:
Extruder barrel diameter (mm) (Figure 1); hi: Feeding section flight depth (mm) (Figure 2); h2:
Pumping section flight depth (mm) (Figure 2); Itot: Total screw length (mm) (Figure 2);11:
Feeding section length (mm) (Figure 2); 12: Pumping section length (mm) Figure 2); b:
Screw pitch (mm) (Figure 2); and e: Flight width (mm) (Figure 2).
In a broad sense, the present invention relates to a starch-based absorbent or superabsorbent material, wherein the starch-based material is essentially composed of a molecular network of amylopectin molecules consisting of either self-entangled amylopectin molecules, cross-linked amylopectin molecules or a mixture of both self-entangled amylopectin molecules and cross-linked amylopectin molecules.
It was previously illustrated by Huppt at a!. (CA 2,308,537) that it is possible to produce a starch-based absorbent having low absorption performances (reported to be 7.5 g/g in 0.9 % NaCl solution) by extrusion. As disclosed hereinafter, it was unexpectedly discovered that the absorption performances of this extruded starch-based material can be significantly improved by increasing the amylopectin content to values in excess of 90% (w/w).
Starch-based absorbent or superabsorbent materials having a CRC
of at least 10 g/g and a FSC of at least 13 g/g, are preferred. It was discovered that such starch-based absorbent or superabsorbent materials can be obtained when comprising a molecular network of amylopectin molecules and wherein the amylopectin content is in excess of 90% (w/w). The molecular network of amylopectin molecules should be consisting of either self-entangled amylopectin molecules or cross-linked amylopectin molecules, both of which can be produced using an extrusion process. In cases wherein the extrudate consists of cross-linked amylopectin molecules, the absorbent or superabsorbent material is obtained by cross-linking, aging and grinding the extrudate.
Self-entangled starches can be produced by an extrusion process using a specific flow-die configuration, aging and grinding the extrudate. It was discovered that the desired molecular network of amylopectin molecules can be obtained by extruding amylopectin with different cross-linkers, under alkaline conditions. Non-limiting examples of such cross-linkers include sodium trimetaphosphate, sodium tripolyphosphate, phosphorous oxychloride, epichlorohydrin, divinyl sulfone, chiorohydrin, bromohydrin, N,N'-methylenebisacrylamide, alkylenebisacrylamides, ethylene glycol diglycidyl ether, diepoxyalkanes, diglycidyl ethers, glyoxal, glutaraldehyde, dialdehydes, diactivated polyethylene glycols (Couture at a!. CA 2,362,006), and mixture thereof.
Examples 1 to 16 (Table 3) illustrate the effect of different extruded amylopectin/amylose blends on the FSC and CRC. The blends were obtained with a single screw extruder using a die (8.5mm diameter) at about 140 C. These blends produced have an amylopectin content ranging from 72% (levels observed in common corn starch) to 99%
(levels observed in pure waxy com starch). The moisture content of all blends was adjusted to about 30%. The results illustrate that blends having an amylopectin content of at least 90% (w/w) and produced using lower die flow rates (Q) provide for optimal performances.
Typical starches possessing the required amylopectin content (90% w/w) are waxy starches. Waxy starches can be selected from the group consisting of waxy maize starch, waxy wheat starch, waxy rice starch, waxy sorghum starch, waxy potato starch, waxy cassava starch, waxy barley starch and mixtures thereof. A
preferred waxy starch is waxy maize starch.
Examples 17 and 18 (Table 4) show two amylopectin extrudates, both produced using an identical extruder throughput "Q", but using a different die extrusion throughput "Qdie". As illustrated in Figure 4, the die throughput (flow rate) is valve-controlled. As can be observed from the experimental results, the use of a lower Qd1e value provides for an extrudate having significantly better FSC and CRC.
The molecular network of cross-linked amylopectin molecules is preferably produced using phosphates cross-linkers since these agents are very well suited to be used in extrusion processes, in addition to being biodegradable.
Preferred phosphate cross-linking agents are sodium trimetaphosphate, sodium tripolyphosphate and phosphorous oxychloride. These cross-linkers produce biodegradable phosphate diester linkages. A more preferred phosphate cross-linking agent is sodium trimetaphosphate.
It was discovered that concentrations of cross-linkers ranging from 0.001 to 2.0 % (w/w on a dry starch basis without added moisture) provide for molecular networks of cross-linked amylopectin molecules having good FSC and CRC performances. In order to achieve efficient cross-linking, the cross-linkers should be mixed with a small amount of alkali. Typical concentrations of alkali range from 0.001 to 2.0 % (w/w on a dry starch basis). Typical paste compositions should comprise a water content ranging from 25% to 45% (w/w), an alkali content ranging from 0.001 to 2.0 % (w/w on a dry starch basis), a cross-linking agent content ranging from 0.001 to 2.0 % (w/w on a dry starch basis), the balance being a starch comprising an amylopectin content of at least 90 %
(w/w).
Non-limiting examples of alkalis include sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, beryllium hydroxide, ammonium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium acetate, potassium acetate, sodium phosphate, sodium hydrogenophosphate, potassium phosphate, potassium hydrogenophosphate and mixture thereof. A preferred alkali is sodium hydroxide.
Examples 19-25 (Table 5) illustrate various amylopectin extrudates produced with different cross-linking agents (also referred too as C-linker) in a twin screw 5 extruder (die diameter of 6 mm) having a moisture content of 30%0. As can be observed from the experimental results, the use of cross-linkers results in amylopectin extrudates having significantly better FSC and CRC performances. As can be concluded from the results shown in Table 5, the FSC and CRC performances can be optimized using specific amounts of a given cross-linker and NaOH (Examples 20, 23 and 25).
10 An efficient extrusion process for the preparation of a starch-based absorbent or superabsorbent material, wherein the starch-based material is essentially composed of a molecular network of amylopectin molecules, either consisting of self-entangled amylopectin molecules or cross-linked amylopectin molecules, is obtained with starch-based starting materials that are in the form of a paste. The paste should be preferably both plastic-like and cohesive. A paste having the required plasticity is obtained when having a moisture content ranging from 25-45% (w/w).
Paste gelatinization using an extruder is a prerequisite to the development of a molecular network of amylopectin molecules, whether consisting of self-entangled amylopectin molecules or cross-linked amylopectin molecules.
Gelatinization is a process described as the melting of starch crystallites resulting in a chaotic molecular network upon completion ("Starch: Chemistry and Technology", Whistler R.L., Bemiller J.N.
and Paschall E.F. Eds., Academic Press, Orlando, 1984, page 287).
Gelatinization of a starch paste comprising a moisture content ranging from 25-45% (w/w), is preferably carried out using an extrudate temperature of at least 130 C. Such temperatures allow for a fully chaotic molecular network to develop.
However, special precautions should be taken in order to avoid any starch degradation.
Such degradation leads to extrusion difficulties in addition to providing materials having reduced absorption performances. Starch degradation typically occurs at elevated extrusion temperatures and long residence times in the extruder.
The die extrusion throughput (Qd;e) has a direct impact on the absorption performances (FSC and CRC) of the extruded starch product, irrespective of whether the amylopectin component is self-entangled or cross-linked. For extrudates comprising a self-entangled amylopectin component, the die extrusion throughput is dependent on the particular die geometry used. Indeed, many factors such as die hole diameter, die geometry and die length have a direct impact on the die extrusion throughput.
Generally, a lower die extrusion throughput leads to materials having better absorption performances.
For extrudates comprising a cross-linked amylopectin component, the die extrusion throughput will once again depend on the particular die geometry used, in addition to being dependent on the cross-linker and alkali levels.
It was unexpectedly discovered that starch-based absorbent or superabsorbent materials comprising a molecular network of amylopectin molecules that are either self-entangled or cross-linked can be efficiently obtained when using a proper combination of die extrusion throughput and die geometry. In a preferred embodiment, the die has the configuration as illustrated in Figures 3 and 4. Furthermore, as mentioned herein above, the die extrusion throughput has a direct impact on the absorption performances of the extruded product; lower die flow rates generally leading to extrudates having better absorption performances (FSC and CRC).
A molecular network of amylopectin molecules, whether composed of self-entangled amylopectin molecules or cross-linked amylopectin molecules, can thus be efficiently obtained when considering both the die extrusion throughput and die configuration.
As can be observed from Table 6, an aging process is required in order to fully develop the FSC and CRC performance of the cross-linked amylopectin extrudates.
An aging period of 48 hours in a convection oven at 60 C is generally sufficient. However, special precautions should be taken in order to avoid any starch degradation.
Once the aging process completed, the extrudate is ground to provide a particulate absorbent material. Particulate materials are preferred since they can be readily mixed with other absorbent materials.
The FSC and CRC for various particulate materials obtained from self-entangled amylopectin extrudates and cross-linked amylopectin extrudates are shown in Tables 7 and 8 respectively. In a preferred embodiment the particulate material obtained from self-entangled amylopectin extrudates and cross-linked amylopectin extrudates has a particle size ranging from 89 to 589 microns (-30mesh/+170 mesh). It can be concluded from both Table 7 and 8, that good FSC and CRC characteristics are obtained with particles ranging in size from 89 to 589 microns. The particulate materials shown in Table 7 were obtained with a SSE having an 8.5 mm die diameter, whereas those shown in Table 8 were obtained with a TSE having a 6 mm die diameter.
Starch-based absorbent or superabsorbent materials comprising a molecular network of either self-entangled or cross-linked amylopectin molecules are useful in many applications. These materials are usually mixed with other co-absorbent materials to produce absorbent mixtures or composites. The contribution of the amylopectin component in these mixtures preferably ranges from 1 to 99% (w/w). Non-limiting examples of co-absorbents include, but are not limited to, synthetic superabsorbent polymers, mannose containing polysaccharides, ionic polysaccharides and fibers. The contribution of the co-absorbent(s) in these mixtures preferably ranges from 1 to 99%
(w/w).
The synthetic superabsorbent polymers as used herein, are obtained from the radical polymerization or the radical graft polymerization of monomers, non-limiting examples of which include acrylic acid, acrylate salts, acrylic ester, acrylic anhydride, methacrylic acid, methacrylate salts, methacrylic esters, methacrylic anhydride, maleic anhydride, maleic salts, maleate esters, acrylamide, acrylonitrile, vinyl alcohol, vinyl pyrrolidone, vinyl acetate, vinyl guanidine, aspartic acid, aspartic salts and mixture thereof.
Non-limiting examples of mannose containing polysaccharides include guar gum, tara gum, locust bean gum, konjac, mesquite gum, psyllium extracts, fenugreek extracts and mixture thereof.
The ionic polysaccharides that can be mixed with the self-entangled or cross-linked amylopectin absorbent or superabsorbent include both cationic and anionic polysaccharides. In a particular embodiment, the absorbent or superabsorbent amylopectin networks can be mixed with both cationic and anionic polysaccharides. In a preferred embodiment, the absorbent or superabsorbent amylopectin networks are mixed with an anionic polysaccharide. Non-limiting examples of anionic polysaccharides include carboxyalkyl polysaccharides, carboxymethyl cellulose, carboxymethyl starch, oxidized polysaccharides, xanthan, carrageenans, pectin and mixtures thereof.
The fibers can be either natural or synthetic. Non-limiting examples of fibers include cellulose, viscose, rayon, cellulose acetate, NylonTM, polyalkylenes, polyethylene, polypropylene, bi-component fibers, polyesters, polylactides, polypropanediols, LyocelFm, sphagnum and mixture thereof.
Paste gelatinization using an extruder is a prerequisite to the development of a molecular network of amylopectin molecules, whether consisting of self-entangled amylopectin molecules or cross-linked amylopectin molecules.
Gelatinization is a process described as the melting of starch crystallites resulting in a chaotic molecular network upon completion ("Starch: Chemistry and Technology", Whistler R.L., Bemiller J.N.
and Paschall E.F. Eds., Academic Press, Orlando, 1984, page 287).
Gelatinization of a starch paste comprising a moisture content ranging from 25-45% (w/w), is preferably carried out using an extrudate temperature of at least 130 C. Such temperatures allow for a fully chaotic molecular network to develop.
However, special precautions should be taken in order to avoid any starch degradation.
Such degradation leads to extrusion difficulties in addition to providing materials having reduced absorption performances. Starch degradation typically occurs at elevated extrusion temperatures and long residence times in the extruder.
The die extrusion throughput (Qd;e) has a direct impact on the absorption performances (FSC and CRC) of the extruded starch product, irrespective of whether the amylopectin component is self-entangled or cross-linked. For extrudates comprising a self-entangled amylopectin component, the die extrusion throughput is dependent on the particular die geometry used. Indeed, many factors such as die hole diameter, die geometry and die length have a direct impact on the die extrusion throughput.
Generally, a lower die extrusion throughput leads to materials having better absorption performances.
For extrudates comprising a cross-linked amylopectin component, the die extrusion throughput will once again depend on the particular die geometry used, in addition to being dependent on the cross-linker and alkali levels.
It was unexpectedly discovered that starch-based absorbent or superabsorbent materials comprising a molecular network of amylopectin molecules that are either self-entangled or cross-linked can be efficiently obtained when using a proper combination of die extrusion throughput and die geometry. In a preferred embodiment, the die has the configuration as illustrated in Figures 3 and 4. Furthermore, as mentioned herein above, the die extrusion throughput has a direct impact on the absorption performances of the extruded product; lower die flow rates generally leading to extrudates having better absorption performances (FSC and CRC).
A molecular network of amylopectin molecules, whether composed of self-entangled amylopectin molecules or cross-linked amylopectin molecules, can thus be efficiently obtained when considering both the die extrusion throughput and die configuration.
As can be observed from Table 6, an aging process is required in order to fully develop the FSC and CRC performance of the cross-linked amylopectin extrudates.
An aging period of 48 hours in a convection oven at 60 C is generally sufficient. However, special precautions should be taken in order to avoid any starch degradation.
Once the aging process completed, the extrudate is ground to provide a particulate absorbent material. Particulate materials are preferred since they can be readily mixed with other absorbent materials.
The FSC and CRC for various particulate materials obtained from self-entangled amylopectin extrudates and cross-linked amylopectin extrudates are shown in Tables 7 and 8 respectively. In a preferred embodiment the particulate material obtained from self-entangled amylopectin extrudates and cross-linked amylopectin extrudates has a particle size ranging from 89 to 589 microns (-30mesh/+170 mesh). It can be concluded from both Table 7 and 8, that good FSC and CRC characteristics are obtained with particles ranging in size from 89 to 589 microns. The particulate materials shown in Table 7 were obtained with a SSE having an 8.5 mm die diameter, whereas those shown in Table 8 were obtained with a TSE having a 6 mm die diameter.
Starch-based absorbent or superabsorbent materials comprising a molecular network of either self-entangled or cross-linked amylopectin molecules are useful in many applications. These materials are usually mixed with other co-absorbent materials to produce absorbent mixtures or composites. The contribution of the amylopectin component in these mixtures preferably ranges from 1 to 99% (w/w). Non-limiting examples of co-absorbents include, but are not limited to, synthetic superabsorbent polymers, mannose containing polysaccharides, ionic polysaccharides and fibers. The contribution of the co-absorbent(s) in these mixtures preferably ranges from 1 to 99%
(w/w).
The synthetic superabsorbent polymers as used herein, are obtained from the radical polymerization or the radical graft polymerization of monomers, non-limiting examples of which include acrylic acid, acrylate salts, acrylic ester, acrylic anhydride, methacrylic acid, methacrylate salts, methacrylic esters, methacrylic anhydride, maleic anhydride, maleic salts, maleate esters, acrylamide, acrylonitrile, vinyl alcohol, vinyl pyrrolidone, vinyl acetate, vinyl guanidine, aspartic acid, aspartic salts and mixture thereof.
Non-limiting examples of mannose containing polysaccharides include guar gum, tara gum, locust bean gum, konjac, mesquite gum, psyllium extracts, fenugreek extracts and mixture thereof.
The ionic polysaccharides that can be mixed with the self-entangled or cross-linked amylopectin absorbent or superabsorbent include both cationic and anionic polysaccharides. In a particular embodiment, the absorbent or superabsorbent amylopectin networks can be mixed with both cationic and anionic polysaccharides. In a preferred embodiment, the absorbent or superabsorbent amylopectin networks are mixed with an anionic polysaccharide. Non-limiting examples of anionic polysaccharides include carboxyalkyl polysaccharides, carboxymethyl cellulose, carboxymethyl starch, oxidized polysaccharides, xanthan, carrageenans, pectin and mixtures thereof.
The fibers can be either natural or synthetic. Non-limiting examples of fibers include cellulose, viscose, rayon, cellulose acetate, NylonTM, polyalkylenes, polyethylene, polypropylene, bi-component fibers, polyesters, polylactides, polypropanediols, LyocelFm, sphagnum and mixture thereof.
The absorbent or superabsorbent materials of the present invention can be employed in a variety of applications such as in disposable sanitary products (i.e.
diapers, incontinence articles, feminine hygiene products, and absorbent dressings), household articles, sealing materials, humectants (i.e. agricultural products for soil conditioning), anti-condensation coatings, water-storing materials (agriculture/horticulture), absorbent paper products, surgical absorbents, pet litter, bandages, wound dressings and as chemical absorbents. Furthermore, they can also be employed in applications related to the transportation of fresh food or seafood, as well as in food packaging applications.
Moreover, the absorbent or superabsorbent materials of the present invention can be employed to absorb a variety of liquids, non-limiting examples of which include physiological fluids, saline solutions, water and aqueous solutions.
diapers, incontinence articles, feminine hygiene products, and absorbent dressings), household articles, sealing materials, humectants (i.e. agricultural products for soil conditioning), anti-condensation coatings, water-storing materials (agriculture/horticulture), absorbent paper products, surgical absorbents, pet litter, bandages, wound dressings and as chemical absorbents. Furthermore, they can also be employed in applications related to the transportation of fresh food or seafood, as well as in food packaging applications.
Moreover, the absorbent or superabsorbent materials of the present invention can be employed to absorb a variety of liquids, non-limiting examples of which include physiological fluids, saline solutions, water and aqueous solutions.
EXPERIMENTAL
Materials Waxy maize starch having an amylopectin content of at least 99%, and Common corn starch having an amylopectin content of about 72%, were purchased from Cargill Corporation (gel #04230 and 03420 respectively);
Sodium Trimetaphosphate (95-97 %), Epichlorohydrin (99 %), and N,N'-Methylenebisacrylamide (99 %) were purchased from Sigma-Aldrich; and Sodium Hydroxide (99 %) was purchased from Laboratoire MAT.
Extruders Two different extruders, a single screw extruder (SSE) and a co-rotating intermeshing twin screw extruder (TSE) were used (Tables 1 and 2).
The Screw design for both the SSE and TSE configuration is illustrated below in Table 2.
Table 1: Single and Twin screw extruders.
Barret &
Configuration Marwfacturor Machine Code= Db HP Die design Screw design SSE1 Figures 1,2 & Figure 3 Killion Table 2 extruders KLR 175 45 15 SSE2 Figures 1,2 & Figure 4 Table 2 Baker Perkins TSE Food MPF-50D 50 25 Figures 1,5,6,7 Figure 8 Machinery & Table 2 Division Table 2: Screw design for both the SSE and TSE configuration.
Single Screw Design Configuration h1 h2 11 12 b Lt t e (mm) (mm) (mm) (mm) (mm) (mm) (mm) SSE1 6.7 2.8 0 0 45 1080 4.5 SSE2 11 5.1 216 540 34 1080 4.5 Twin Screw Design Feed port Type of element Description Number of elements Twin lead feed screw Figure 5 42/3 Single lead screw Figure 6 2 Paddle blocks Figure 7 21 (30 forward staggering angle) Single lead screw Figure 6 5 Die Grinder A Braun model KSM coffee grinder was used to grind the produced 5 ektrudate samples.
Test methods As discussed in Modem Superabsorbent Polymer Technology (Buchholz F.L. and Graham A.T. Eds., Wiley-VCH, New York, 1998, section 4.6.1.
Swelling Capacity: Theory and Practice, p. 147), several methods of measurement are used in order 10 to characterize the swelling capacity of a polymer. In the field of superabsorbents, the Gravimetric Swelling Capacity [also called the Free Swell Capacity (FSC)] and the Centrifuge Capacity [also called the Centrifuge Retention Capacity (CRC)] are recommended methods. The FSC and the CRC were used to compare the swelling capacities of the obtained absorbent products.
Tea baps for FSC and CRC measurements Tea bags (6 x 6 cm) were made from heat sealable AhlstromTM filter paper (16.5 0.5 g/m2).
FSC measurements The Free Swell Capacity (FSC) in a 0.9% NaCl solution was determined according to the recommended test method 440.2-02 from EDANA (Free Swell Capacity No. 440.2-02, Recommended test Method: Superabsorbent materials-Polyacrylate superabsorbent powders-Free Swell Capacity in Saline by Gravimetric Determination, 2002).
CRC measurements The Centrifuge Retention Capacity (CRC) in a 0.9% NaCl solution was determined according to the recommended test method 441.2-02 from EDANA
(Centrifuge Retention Capacity No. 441.2-02, Recommended Test Method:
Superabsorbent materials-Polyacrylate superabsorbent powders-Determination of Fluid Retention Capacity in Saline Solution After Centrifugation, 2002).
Particle size for FSC and CRC measurements Al the FSC and CRC measurements were carried out using sieved products. Only particles ranging in size from 89 to 589 microns (-30 mesh/+170 mesh) were used for the FSC and CRC measurements.
Table 3 illustrates the effect on the FSC and CRC of different amylopectin/amylose blends extruded through a 8.5mm diameter die. For each example, a paste was prepared by weighing 5 Kg of amylopectin/amylose blend (having a moisture content of about 9%), followed by adding 1.5 Kg of water to obtain a total moisture content of about 30%. The blends were prepared from common com starch having an amylopectin content of 72%, and waxy maize starch having an amylopectin content of at least 99%. The pastes were hand-fed into SSE1 having the following barrel/die temperature profile:
Tbl=50 C, Tb2=65 C, Tb3=135 C, Td=135 C. The obtained extrudates were subsequently aged for 2 days at 85 C in a convection oven and ground with a coffee grinder.
As can be concluded from the results shown in Table 3, amylopectin extruded at low flow rates provides extrudates having superior FSC and CRC characteristics. Furthermore, starches having an amylopectin content of at least 90%, provide extrudates having significantly improved FSC and CRC characteristics.
Table 3: Effect on the FSC and CRC of different amylopectin/amylose blends extruded through a 8.5mm diameter die.
Blend preparation before adding water %Waxy %Common SZ Q T FSC CRC
# %Amylopectin maize corn 1 0 100 72 25 9.6 140 8.6 5.1 2 0 100 72 40 8-6 138 8.1 i 5.3 3 0 100 72 155 23 139 8.2 5.1 4 50 50 86 24 4.1 141 10.4 8.3 5 50 50 86 ' 40 9.5 t 140 10.5 8.6 6 50 50 86 55 11.3 137 9.8 8.0 7 66.7 33.3 90 15 4.4 142 13.4 10.3 8 66.7 33.3 90 31 7.4 141 13.9 10.8 9 66.7 133.3 90 fi 43 9.8 141 15.0 8,6 66.7 33.3 90 55 12.8 140 114.6 7.9 11 85.2 14.8 95 15 4.4 141 17.5 12.4 12 85.2 114.8 95 31 9.6 1140 16.6 13.2 13 85.2 14.8 195 43 11.5 138 17.5 111.1 14 1,100 0 99 1 10 1 4 5 1 141 19.5 15.0 1100 10 99 25 176 140 20.7 14.5 16 100 0 - -' 99 37 12.3 1141 21.6 12.2 Table 4 illustrates the effect of the die extrusion throughput (Qft) and the die geometry on the FSC and CRC of the extrudates. The die extrusion throughput was controlled by a valve as illustrated in Figure 4. A molecular network of self-entangled starch was formed with this die. For each example, a paste was prepared by weighing 5 Kg of a waxy maize starch (having a moisture content of about 9%), followed by adding 1.5 Kg of water to obtain a total moisture content of about 30%. The pastes were hand-fed into SSE2, turning 30 RPM, and having the following barrel/die temperature profile:
Tb1=50 C, Tb2=65 C, Tb3=135 C, Td=135 C. The obtained extrudates were subsequently aged for 2 days at 85 C in a convection oven and ground with a coffee grinder. As can be concluded from the results shown in Table 4, a lower die extrusion throughput and using the die configuration as illustrated in Figure 4, provides extrudates having superior FSC and CRC
characteristics.
Table 4: Effect of the die extrusion throughput (Qdje) on the FSC and CRC of the extrudates.
Q,. T FSC CRC
17 15.1 15.1 140 15.5 13.4 18 15.1 4.5 140 18.9 16.5 Table 5 illustrates the effect on the FSC and CRC of various amylopectin extrudates produced with or without crosslinking agent (also referred too as C-linker) using a TSE (die diameter of 6 mm). For each example, a paste was prepared by weighing 7 Kg of waxy maize starch (having a moisture content of about 9%), followed by adding 2.1 Kg of water to obtain a total moisture content of about 30%. The pastes were fed into the TSE (turning at 100 RPM) using a K-Tron T35" volumetric feeder.
When a cross-linking agent is used, the crosslinker is first dissolved in the water, along with the appropriate amount of sodium hydroxide, prior to adding the water to the waxy maize starch. The TSE had the following barrel/die temperature profile: Tb1=43 C, Tb2=59 C, Tb3=80 C, Tb4=108 C, Tb5=132 C, Tb6=151 C, Tb7=159 C, Tb8=159 C (the die was not heated). The obtained extrudates were subsequently aged for 2 days at 60 C in a convection oven and ground with a coffee grinder. As can be concluded from the results shown in Table 5, the FSC and CRC performances can be optimized using specific amounts of a given cross-linker and NaOH (Examples 20, 23 and 25).
Table 5: Effect on the FSC and CRC of various amylopectin extrudates produced with or without crosslinking agent.
(weight C-linker or NaOH/ weight = amylopectin) X 100%
# , Q C-linker T FSC CRC
C-linker NaOH
19 19.6 None 0 0 140 13.2 1.1 20 21.2 MBA 0.05 0.026 140 16.6 14.7 21 29.4 None 0 0 136 7.5 1.7 22 31.3 STMP 0.13 0025 1,137 16,0 137 23 31.1 STMP 0.63 0.025 137 20.2 16.0 24 129.9 STMP i 1.27 0.025 140 20.0 13.8 25 27.0 ECH 0.04 0.04 143 17.7 15.4 ECH Epichlorohydrin; STMP: Sodium Trimetaphosphate; MBA: N,N'-Methylenebisacrylamide Table 6 illustrates the effect of the aging process on the FSC and CRC
of crosslinked amylopectin extrudates. More specifically, crosslinked amylopectin extrudates aged at room temperature and in a convection oven at 60 C, are illustrated. A
paste was prepared by weighing 7 Kg of waxy maize starch (having a moisture content of about 9 %), followed by adding 2.1 Kg of an aqueous solution of sodium hydroxide (0.02%
on a dry starch basis) comprising STMP (0.1% on a dry starch basis) to obtain a total moisture content of about 30 %. The paste was fed into the TSE (turning at 100 RPM) at 33 Kg/h using a K-Tron T35'" volumetric feeder. The TSE had the following barrel/die temperature profile: Tb1=56 C, Tb2=79 C, Tb3=105 C, Tb4=144 C, Tb5=180 C, Tb6=196 C, Tb7=200 C, Tb8=204 C (the die was not heated). The extrudate temperature was 144 C.
As can be concluded from the results shown in Table 6, for an identical extrudate, a shorter aging process at higher temperatures provides extrudates having superior FSC
and CRC
characteristics.
Table 6: Effect of the aging process on the FSC and CRC of crosslinked amylopectin extrudates.
# Aging Aging time FSC CRC
temperature 26 Room 240 hours 116.7 3.2 temperature 27 60 C 48 hours 19.2 113.4 5 Table 7 illustrates the effect of the particle size of ground amylopectin extrudates on the FSC and CRC. The extrudates were obtained using a SSE having an 8.5 mm die diameter. The extrudate (obtained from example 14) was ground with a coffee grinder and sieved using a Tyler Rota-TapTM test sieve shaker.
Table 7: Effect of the particle size of ground amylopectin extrudates on the FSC
10 and CRC.
# Particle size -- - --- - FSC CRC
Mesh Microns 28 +30 >589 10.3 9.5 29 -30/+40 417 to 589 15 9 14.4 -40/+50 295 to 417 19.1 16.9 31 -501+60 246 to 295 21.3 18.7 32 -60/+100 1 147 to 246 21.9 18.7 33 -100/+170 189to 147 17.4 14.4 34 -170 89 20.7 10.5 Table 8 illustrates the effect of the particle size of ground STMP
crosslinked amylopectin extrudates on the FSC and CRC. The extrudates were obtained using a TSE having an 6 mm die diameter. The extrudate (obtained from example 22) was ground with a coffee grinder and sieved using a Tyler Rota-TapTM test sieve shaker.
Table 8: Effect of the particle size of ground STMP crosslinked amylopectin extrudates on the FSC and CRC.
# Particle size FSC CRC
Mesh Microns 35 +30 >589 12.8 11.5 36 -30/+40 417 to 589 115.7 14.0 37 J -40/+50 295 to 417 18.0 115.8 38 50/+60 246 to 295 18.9 16.2 39 -60/+100 147 to 246 119.2 j 15 5 40 -100/+170 89 to 147 18.4 14.0 41 1-170 < 89 14.7 J7.4 As can be concluded from the results shown in Tables 7 and 8, good FSC and CRC characteristics are obtained with particles ranging in size from 89 to 589 microns.
Although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified without departing from the spirit, scope and nature of the subject invention, as defined in the appended claims.
Materials Waxy maize starch having an amylopectin content of at least 99%, and Common corn starch having an amylopectin content of about 72%, were purchased from Cargill Corporation (gel #04230 and 03420 respectively);
Sodium Trimetaphosphate (95-97 %), Epichlorohydrin (99 %), and N,N'-Methylenebisacrylamide (99 %) were purchased from Sigma-Aldrich; and Sodium Hydroxide (99 %) was purchased from Laboratoire MAT.
Extruders Two different extruders, a single screw extruder (SSE) and a co-rotating intermeshing twin screw extruder (TSE) were used (Tables 1 and 2).
The Screw design for both the SSE and TSE configuration is illustrated below in Table 2.
Table 1: Single and Twin screw extruders.
Barret &
Configuration Marwfacturor Machine Code= Db HP Die design Screw design SSE1 Figures 1,2 & Figure 3 Killion Table 2 extruders KLR 175 45 15 SSE2 Figures 1,2 & Figure 4 Table 2 Baker Perkins TSE Food MPF-50D 50 25 Figures 1,5,6,7 Figure 8 Machinery & Table 2 Division Table 2: Screw design for both the SSE and TSE configuration.
Single Screw Design Configuration h1 h2 11 12 b Lt t e (mm) (mm) (mm) (mm) (mm) (mm) (mm) SSE1 6.7 2.8 0 0 45 1080 4.5 SSE2 11 5.1 216 540 34 1080 4.5 Twin Screw Design Feed port Type of element Description Number of elements Twin lead feed screw Figure 5 42/3 Single lead screw Figure 6 2 Paddle blocks Figure 7 21 (30 forward staggering angle) Single lead screw Figure 6 5 Die Grinder A Braun model KSM coffee grinder was used to grind the produced 5 ektrudate samples.
Test methods As discussed in Modem Superabsorbent Polymer Technology (Buchholz F.L. and Graham A.T. Eds., Wiley-VCH, New York, 1998, section 4.6.1.
Swelling Capacity: Theory and Practice, p. 147), several methods of measurement are used in order 10 to characterize the swelling capacity of a polymer. In the field of superabsorbents, the Gravimetric Swelling Capacity [also called the Free Swell Capacity (FSC)] and the Centrifuge Capacity [also called the Centrifuge Retention Capacity (CRC)] are recommended methods. The FSC and the CRC were used to compare the swelling capacities of the obtained absorbent products.
Tea baps for FSC and CRC measurements Tea bags (6 x 6 cm) were made from heat sealable AhlstromTM filter paper (16.5 0.5 g/m2).
FSC measurements The Free Swell Capacity (FSC) in a 0.9% NaCl solution was determined according to the recommended test method 440.2-02 from EDANA (Free Swell Capacity No. 440.2-02, Recommended test Method: Superabsorbent materials-Polyacrylate superabsorbent powders-Free Swell Capacity in Saline by Gravimetric Determination, 2002).
CRC measurements The Centrifuge Retention Capacity (CRC) in a 0.9% NaCl solution was determined according to the recommended test method 441.2-02 from EDANA
(Centrifuge Retention Capacity No. 441.2-02, Recommended Test Method:
Superabsorbent materials-Polyacrylate superabsorbent powders-Determination of Fluid Retention Capacity in Saline Solution After Centrifugation, 2002).
Particle size for FSC and CRC measurements Al the FSC and CRC measurements were carried out using sieved products. Only particles ranging in size from 89 to 589 microns (-30 mesh/+170 mesh) were used for the FSC and CRC measurements.
Table 3 illustrates the effect on the FSC and CRC of different amylopectin/amylose blends extruded through a 8.5mm diameter die. For each example, a paste was prepared by weighing 5 Kg of amylopectin/amylose blend (having a moisture content of about 9%), followed by adding 1.5 Kg of water to obtain a total moisture content of about 30%. The blends were prepared from common com starch having an amylopectin content of 72%, and waxy maize starch having an amylopectin content of at least 99%. The pastes were hand-fed into SSE1 having the following barrel/die temperature profile:
Tbl=50 C, Tb2=65 C, Tb3=135 C, Td=135 C. The obtained extrudates were subsequently aged for 2 days at 85 C in a convection oven and ground with a coffee grinder.
As can be concluded from the results shown in Table 3, amylopectin extruded at low flow rates provides extrudates having superior FSC and CRC characteristics. Furthermore, starches having an amylopectin content of at least 90%, provide extrudates having significantly improved FSC and CRC characteristics.
Table 3: Effect on the FSC and CRC of different amylopectin/amylose blends extruded through a 8.5mm diameter die.
Blend preparation before adding water %Waxy %Common SZ Q T FSC CRC
# %Amylopectin maize corn 1 0 100 72 25 9.6 140 8.6 5.1 2 0 100 72 40 8-6 138 8.1 i 5.3 3 0 100 72 155 23 139 8.2 5.1 4 50 50 86 24 4.1 141 10.4 8.3 5 50 50 86 ' 40 9.5 t 140 10.5 8.6 6 50 50 86 55 11.3 137 9.8 8.0 7 66.7 33.3 90 15 4.4 142 13.4 10.3 8 66.7 33.3 90 31 7.4 141 13.9 10.8 9 66.7 133.3 90 fi 43 9.8 141 15.0 8,6 66.7 33.3 90 55 12.8 140 114.6 7.9 11 85.2 14.8 95 15 4.4 141 17.5 12.4 12 85.2 114.8 95 31 9.6 1140 16.6 13.2 13 85.2 14.8 195 43 11.5 138 17.5 111.1 14 1,100 0 99 1 10 1 4 5 1 141 19.5 15.0 1100 10 99 25 176 140 20.7 14.5 16 100 0 - -' 99 37 12.3 1141 21.6 12.2 Table 4 illustrates the effect of the die extrusion throughput (Qft) and the die geometry on the FSC and CRC of the extrudates. The die extrusion throughput was controlled by a valve as illustrated in Figure 4. A molecular network of self-entangled starch was formed with this die. For each example, a paste was prepared by weighing 5 Kg of a waxy maize starch (having a moisture content of about 9%), followed by adding 1.5 Kg of water to obtain a total moisture content of about 30%. The pastes were hand-fed into SSE2, turning 30 RPM, and having the following barrel/die temperature profile:
Tb1=50 C, Tb2=65 C, Tb3=135 C, Td=135 C. The obtained extrudates were subsequently aged for 2 days at 85 C in a convection oven and ground with a coffee grinder. As can be concluded from the results shown in Table 4, a lower die extrusion throughput and using the die configuration as illustrated in Figure 4, provides extrudates having superior FSC and CRC
characteristics.
Table 4: Effect of the die extrusion throughput (Qdje) on the FSC and CRC of the extrudates.
Q,. T FSC CRC
17 15.1 15.1 140 15.5 13.4 18 15.1 4.5 140 18.9 16.5 Table 5 illustrates the effect on the FSC and CRC of various amylopectin extrudates produced with or without crosslinking agent (also referred too as C-linker) using a TSE (die diameter of 6 mm). For each example, a paste was prepared by weighing 7 Kg of waxy maize starch (having a moisture content of about 9%), followed by adding 2.1 Kg of water to obtain a total moisture content of about 30%. The pastes were fed into the TSE (turning at 100 RPM) using a K-Tron T35" volumetric feeder.
When a cross-linking agent is used, the crosslinker is first dissolved in the water, along with the appropriate amount of sodium hydroxide, prior to adding the water to the waxy maize starch. The TSE had the following barrel/die temperature profile: Tb1=43 C, Tb2=59 C, Tb3=80 C, Tb4=108 C, Tb5=132 C, Tb6=151 C, Tb7=159 C, Tb8=159 C (the die was not heated). The obtained extrudates were subsequently aged for 2 days at 60 C in a convection oven and ground with a coffee grinder. As can be concluded from the results shown in Table 5, the FSC and CRC performances can be optimized using specific amounts of a given cross-linker and NaOH (Examples 20, 23 and 25).
Table 5: Effect on the FSC and CRC of various amylopectin extrudates produced with or without crosslinking agent.
(weight C-linker or NaOH/ weight = amylopectin) X 100%
# , Q C-linker T FSC CRC
C-linker NaOH
19 19.6 None 0 0 140 13.2 1.1 20 21.2 MBA 0.05 0.026 140 16.6 14.7 21 29.4 None 0 0 136 7.5 1.7 22 31.3 STMP 0.13 0025 1,137 16,0 137 23 31.1 STMP 0.63 0.025 137 20.2 16.0 24 129.9 STMP i 1.27 0.025 140 20.0 13.8 25 27.0 ECH 0.04 0.04 143 17.7 15.4 ECH Epichlorohydrin; STMP: Sodium Trimetaphosphate; MBA: N,N'-Methylenebisacrylamide Table 6 illustrates the effect of the aging process on the FSC and CRC
of crosslinked amylopectin extrudates. More specifically, crosslinked amylopectin extrudates aged at room temperature and in a convection oven at 60 C, are illustrated. A
paste was prepared by weighing 7 Kg of waxy maize starch (having a moisture content of about 9 %), followed by adding 2.1 Kg of an aqueous solution of sodium hydroxide (0.02%
on a dry starch basis) comprising STMP (0.1% on a dry starch basis) to obtain a total moisture content of about 30 %. The paste was fed into the TSE (turning at 100 RPM) at 33 Kg/h using a K-Tron T35'" volumetric feeder. The TSE had the following barrel/die temperature profile: Tb1=56 C, Tb2=79 C, Tb3=105 C, Tb4=144 C, Tb5=180 C, Tb6=196 C, Tb7=200 C, Tb8=204 C (the die was not heated). The extrudate temperature was 144 C.
As can be concluded from the results shown in Table 6, for an identical extrudate, a shorter aging process at higher temperatures provides extrudates having superior FSC
and CRC
characteristics.
Table 6: Effect of the aging process on the FSC and CRC of crosslinked amylopectin extrudates.
# Aging Aging time FSC CRC
temperature 26 Room 240 hours 116.7 3.2 temperature 27 60 C 48 hours 19.2 113.4 5 Table 7 illustrates the effect of the particle size of ground amylopectin extrudates on the FSC and CRC. The extrudates were obtained using a SSE having an 8.5 mm die diameter. The extrudate (obtained from example 14) was ground with a coffee grinder and sieved using a Tyler Rota-TapTM test sieve shaker.
Table 7: Effect of the particle size of ground amylopectin extrudates on the FSC
10 and CRC.
# Particle size -- - --- - FSC CRC
Mesh Microns 28 +30 >589 10.3 9.5 29 -30/+40 417 to 589 15 9 14.4 -40/+50 295 to 417 19.1 16.9 31 -501+60 246 to 295 21.3 18.7 32 -60/+100 1 147 to 246 21.9 18.7 33 -100/+170 189to 147 17.4 14.4 34 -170 89 20.7 10.5 Table 8 illustrates the effect of the particle size of ground STMP
crosslinked amylopectin extrudates on the FSC and CRC. The extrudates were obtained using a TSE having an 6 mm die diameter. The extrudate (obtained from example 22) was ground with a coffee grinder and sieved using a Tyler Rota-TapTM test sieve shaker.
Table 8: Effect of the particle size of ground STMP crosslinked amylopectin extrudates on the FSC and CRC.
# Particle size FSC CRC
Mesh Microns 35 +30 >589 12.8 11.5 36 -30/+40 417 to 589 115.7 14.0 37 J -40/+50 295 to 417 18.0 115.8 38 50/+60 246 to 295 18.9 16.2 39 -60/+100 147 to 246 119.2 j 15 5 40 -100/+170 89 to 147 18.4 14.0 41 1-170 < 89 14.7 J7.4 As can be concluded from the results shown in Tables 7 and 8, good FSC and CRC characteristics are obtained with particles ranging in size from 89 to 589 microns.
Although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified without departing from the spirit, scope and nature of the subject invention, as defined in the appended claims.
Claims (35)
1. A particulate absorbent material consisting of a gelatinized starch extrudate, the starch extrudate comprising at least 90% (w/w) amylopectin, wherein said particulate absorbent material comprises particles ranging from µm to 589 µm.
2. The particulate absorbent material of claim 1, wherein the gelatinized starch extrudate comprises self-entangled starch.
3. The particulate absorbent material of claim 1, wherein the gelatinized starch extrudate comprises cross-linked starch.
4. The particulate absorbent material of claims 2 and 3, having a centrifuge retention capacity of at least 10 g/g and a free swell capacity of at least 13 g/g.
5. The particulate absorbent material of claims 2 and 3, wherein the gelatinized starch extrudate is produced from a waxy starch.
6. The particulate absorbent material of claim 5, wherein said waxy starch is selected from the group consisting of waxy maize starch, waxy wheat starch, waxy rice starch, waxy sorghum starch, waxy potato starch, waxy cassava starch, waxy barley starch and mixtures thereof.
7. The particulate absorbent material of claim 6, wherein said waxy starch is waxy maize starch.
8. The particulate absorbent material of claim 3, wherein said cross-linked starch is cross-linked with a cross-linker selected from the group consisting of sodium trimetaphosphate, sodium tripolyphosphate, phosphorous oxychloride, phosphoryl chloride, epichlorohydrin, divinyl sulfone, ethylene glycol diglycidyl ether, chlorohydrin, bromohydrin, N,N'-Methylenebisacrylamide, alkylenebisacrylamides, diepoxyalkanes, diglycidyl ethers, glyoxal, dialdehydes, activated polyethylene glycols, and mixtures thereof.
9. The particulate absorbent material of claim 8, wherein the cross-linker is selected from the group consisting of phosphorous oxychloride, sodium trimetaphosphate, sodium tripolyphosphate and mixtures thereof.
10. The particulate absorbent material of claim 9, wherein the cross-linker is sodium trimetaphosphate.
11. A process for producing a particulate absorbent material consisting of a gelatinized starch extrudate, the process comprising the steps of:
(a) mixing a starch comprising at least 90% (w/w) amylopectin with water to produce a paste;
(b) feeding the paste into an extruder to produce an extrudate;
(c) aging the extrudate; and (d) grinding the extrudate.
(a) mixing a starch comprising at least 90% (w/w) amylopectin with water to produce a paste;
(b) feeding the paste into an extruder to produce an extrudate;
(c) aging the extrudate; and (d) grinding the extrudate.
12. A process for producing a particulate absorbent material consisting of a gelatinized starch extrudate, the process comprising the steps of:
(a) mixing a starch comprising at least 90% (w/w) amylopectin with water, an alkali and a cross-linking agent to produce a paste (b) feeding the paste into an extruder to produce an extrudate;
(c) aging the extrudate; and (d) grinding the extrudate.
(a) mixing a starch comprising at least 90% (w/w) amylopectin with water, an alkali and a cross-linking agent to produce a paste (b) feeding the paste into an extruder to produce an extrudate;
(c) aging the extrudate; and (d) grinding the extrudate.
13. The process as defined in claim 12, the paste comprising from 0.001 to 2.0% (w/w) of the crosslinking agent.
14. The process as defined in claim 12, the paste comprising from 0.001 to 2.0% (w/w) of the alkali.
15. The process as defined in claims 11 and 12, the starch-based paste having a moisture content ranging from 25 % to 45 %.
16. The process, as defined in claim 13, wherein the cross-linking agent is being selected from the group consisting of sodium trimetaphosphate, sodium tripolyphosphate, phosphoryl oxychloride, phosphorous chloride, epichlorohydrin, divinyl sulfone, chlorohydrin, bromohydrin, N,N'-Methylenebisacrylamide, alkylenebisacrylamides, ethylene glycol diglycidyl ether, diepoxyalkanes, diglycidyl ethers, glyoxal, dialdehydes, activated polyethylene glycols and mixtures thereof.
17. The process as defined in claim 16, wherein the cross-linking agent is being selected from the group consisting of sodium trimetaphosphate, sodium tripolyphosphate and phosphoryl oxychloride.
18. The process as defined in claim 17, wherein the cross-linking agent is sodium trimetaphosphate.
19. The process as defined in claim 14, wherein the alkali is being selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, beryllium hydroxide, ammonium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium acetate, potassium acetate, sodium phosphate, sodium hydrogenophosphate, potassium phosphate, potassium hydrogenophosphate and mixtures thereof.
20. The process, as defined in claim 19, wherein the alkali is sodium hydroxide.
21. The process as defined in claims 11 and 12, wherein the extrudate has a temperature of at least 130°C when exiting the extruder.
22. A process as defined in claim 21 wherein the extrudate is aged at least 48 hours at a temperature of at least 50°C.
23. The process as defined in claims 11 and 12, wherein the grinding produces particles ranging in size from 89 µm to 589 µm.
24. An absorbent mixture comprising:
a) a particulate absorbent material as defined in claim 1;
and b) a co-absorbent material.
a) a particulate absorbent material as defined in claim 1;
and b) a co-absorbent material.
25. The absorbent mixture as defined in claim 24, wherein the co-absorbent material is selected from the group consisting of synthetic superabsorbent polymers, mannose containing polysaccharides, ionic polysaccharides, fibers and mixtures thereof.
26. The absorbent mixture as defined in claim 25, wherein the synthetic superabsorbent polymers are obtained by polymerization of monomers selected from the group consisting of acrylic acid, acrylate salts, acrylic ester, acrylic anhydride, methacrylic acid, methacrylate salts, methacrylic esters, methacrylic anhydride, maleic anhydride, maleic salts, maleate esters, acrylamide, acrylonitrile, vinyl alcohol, vinyl pyrrolidone, vinyl acetate, vinyl guanidine, aspartic acid, aspartic salts and mixtures thereof.
27. The absorbent mixture as defined in claim 25, wherein the mannose containing polysaccharides are selected from the group consisting of guar gum, tara gum, locust bean gum, konjac, mesquite gum, psyllium extracts, fenugreek extracts and mixtures thereof.
28. The absorbent mixture as defined in claim 25, wherein the ionic polysaccharides comprise anionic and cationic polysaccharides.
29. The absorbent mixture as defined in claim 28, wherein the anionic polysaccharides are selected from the group consisting of carboxyalkyl polysaccharides, oxidized polysaccharides, sulphated polysaccharides, polysaccharides half-esters, carboxymethyl cellulose, carboxymethyl starch, xanthan, carrageenans, pectin and mixtures thereof.
30. The absorbent mixture as defined in claim 25, wherein the fibers are selected from the group consisting of cellulose, viscose, rayon, cellulose acetate, Nylon TM, polyalkylenes, polyethylene, polypropylene, bi-component fibers, polyesters, polylactides, polypropanediols, Lyocell.TM.
sphagnum and mixtures thereof.
sphagnum and mixtures thereof.
31. An absorbent product comprising the absorbent mixture of claim 24 for absorbing liquids selected from the group consisting of aqueous solutions, water, physiological solutions and saline solutions.
32. The absorbent product as defined in claim 31, wherein the absorbent product is selected from the group consisting of diapers, incontinence articles, sanitary napkins, water-storing materials, absorbent paper products, surgical absorbents, pet litter, bandages, wound dressings and food absorbent pads.
33. An absorbent product comprising the particulate absorbent material of claim 1 for absorbing liquids selected from the group consisting of aqueous solutions, water, physiological solutions and saline solutions.
34. The absorbent product as defined in claim 33, wherein the absorbent product is selected from the group consisting of diapers, incontinence articles, sanitary napkins, water-storing materials, absorbent paper products, surgical absorbents, pet litter, bandages, wound dressings and food absorbent pads.
35. The particulate absorbent material of claim 1, wherein the starch extrudate comprises non-degraded starch.
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