GB2061974A - Absorbent products, processes and compositions - Google Patents
Absorbent products, processes and compositions Download PDFInfo
- Publication number
- GB2061974A GB2061974A GB8034643A GB8034643A GB2061974A GB 2061974 A GB2061974 A GB 2061974A GB 8034643 A GB8034643 A GB 8034643A GB 8034643 A GB8034643 A GB 8034643A GB 2061974 A GB2061974 A GB 2061974A
- Authority
- GB
- United Kingdom
- Prior art keywords
- polymer
- absorbent
- product
- thermoplastic
- matrix
- 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.)
- Granted
Links
- 239000002250 absorbent Substances 0.000 title claims abstract description 175
- 230000002745 absorbent Effects 0.000 title claims abstract description 173
- 239000000203 mixture Substances 0.000 title claims description 70
- 238000000034 method Methods 0.000 title claims description 36
- 239000011159 matrix material Substances 0.000 claims abstract description 65
- 229920001169 thermoplastic Polymers 0.000 claims abstract description 29
- 229920000620 organic polymer Polymers 0.000 claims abstract description 10
- 230000008961 swelling Effects 0.000 claims abstract description 6
- 229920000642 polymer Polymers 0.000 claims description 110
- 239000000047 product Substances 0.000 claims description 94
- 229920001400 block copolymer Polymers 0.000 claims description 47
- 229920000058 polyacrylate Polymers 0.000 claims description 37
- -1 aliphatic diene Chemical class 0.000 claims description 34
- 229920000728 polyester Polymers 0.000 claims description 32
- 229920002472 Starch Polymers 0.000 claims description 24
- 239000008107 starch Substances 0.000 claims description 24
- 235000019698 starch Nutrition 0.000 claims description 24
- 239000002245 particle Substances 0.000 claims description 22
- 239000004416 thermosoftening plastic Substances 0.000 claims description 21
- 239000001913 cellulose Substances 0.000 claims description 14
- 229920001282 polysaccharide Polymers 0.000 claims description 14
- 239000005017 polysaccharide Substances 0.000 claims description 14
- 229920002678 cellulose Polymers 0.000 claims description 13
- 150000004676 glycans Chemical class 0.000 claims description 11
- 229920002785 Croscarmellose sodium Polymers 0.000 claims description 9
- 239000007788 liquid Substances 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 7
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 5
- 238000005266 casting Methods 0.000 claims description 5
- 229920002725 thermoplastic elastomer Polymers 0.000 claims description 5
- PUPZLCDOIYMWBV-UHFFFAOYSA-N (+/-)-1,3-Butanediol Chemical compound CC(O)CCO PUPZLCDOIYMWBV-UHFFFAOYSA-N 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 239000003960 organic solvent Substances 0.000 claims description 4
- 229920006344 thermoplastic copolyester Polymers 0.000 claims description 3
- 229920005613 synthetic organic polymer Polymers 0.000 claims description 2
- 125000004067 aliphatic alkene group Chemical group 0.000 claims 5
- 239000007859 condensation product Substances 0.000 claims 3
- 125000004185 ester group Chemical group 0.000 claims 3
- 238000001125 extrusion Methods 0.000 abstract description 17
- 238000000807 solvent casting Methods 0.000 abstract description 6
- 239000010408 film Substances 0.000 description 92
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 28
- 229920001971 elastomer Polymers 0.000 description 19
- 239000000463 material Substances 0.000 description 19
- 239000005060 rubber Substances 0.000 description 16
- 229920002633 Kraton (polymer) Polymers 0.000 description 15
- 150000002148 esters Chemical class 0.000 description 13
- 239000012530 fluid Substances 0.000 description 13
- NIXOWILDQLNWCW-UHFFFAOYSA-M acrylate group Chemical group C(C=C)(=O)[O-] NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 12
- 150000002009 diols Chemical class 0.000 description 12
- VSKJLJHPAFKHBX-UHFFFAOYSA-N 2-methylbuta-1,3-diene;styrene Chemical compound CC(=C)C=C.C=CC1=CC=CC=C1.C=CC1=CC=CC=C1 VSKJLJHPAFKHBX-UHFFFAOYSA-N 0.000 description 11
- 238000004132 cross linking Methods 0.000 description 11
- 239000000178 monomer Substances 0.000 description 11
- 239000000843 powder Substances 0.000 description 11
- 239000002904 solvent Substances 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 10
- 238000000576 coating method Methods 0.000 description 10
- 239000005977 Ethylene Substances 0.000 description 9
- 239000002253 acid Substances 0.000 description 9
- 238000002360 preparation method Methods 0.000 description 9
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 8
- RRHGJUQNOFWUDK-UHFFFAOYSA-N Isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 description 8
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 8
- 239000000853 adhesive Substances 0.000 description 8
- 230000001070 adhesive effect Effects 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 239000000758 substrate Substances 0.000 description 8
- BOXSVZNGTQTENJ-UHFFFAOYSA-L zinc dibutyldithiocarbamate Chemical compound [Zn+2].CCCCN(C([S-])=S)CCCC.CCCCN(C([S-])=S)CCCC BOXSVZNGTQTENJ-UHFFFAOYSA-L 0.000 description 8
- JZODKRWQWUWGCD-UHFFFAOYSA-N 2,5-di-tert-butylbenzene-1,4-diol Chemical compound CC(C)(C)C1=CC(O)=C(C(C)(C)C)C=C1O JZODKRWQWUWGCD-UHFFFAOYSA-N 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000003963 antioxidant agent Substances 0.000 description 7
- 239000003054 catalyst Substances 0.000 description 7
- 239000011347 resin Substances 0.000 description 7
- 229920005989 resin Polymers 0.000 description 7
- KAKZBPTYRLMSJV-UHFFFAOYSA-N vinyl-ethylene Natural products C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 7
- 229920013623 Solprene Polymers 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 238000009472 formulation Methods 0.000 description 6
- 238000012986 modification Methods 0.000 description 6
- 230000004048 modification Effects 0.000 description 6
- 230000036961 partial effect Effects 0.000 description 6
- 230000000379 polymerizing effect Effects 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 5
- 239000004820 Pressure-sensitive adhesive Substances 0.000 description 5
- 229910052783 alkali metal Inorganic materials 0.000 description 5
- 239000004744 fabric Substances 0.000 description 5
- 229920000578 graft copolymer Polymers 0.000 description 5
- 229920000233 poly(alkylene oxides) Polymers 0.000 description 5
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 150000007513 acids Chemical class 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- FACXGONDLDSNOE-UHFFFAOYSA-N buta-1,3-diene;styrene Chemical compound C=CC=C.C=CC1=CC=CC=C1.C=CC1=CC=CC=C1 FACXGONDLDSNOE-UHFFFAOYSA-N 0.000 description 4
- 229920001577 copolymer Polymers 0.000 description 4
- 238000007334 copolymerization reaction Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 4
- 229920000468 styrene butadiene styrene block copolymer Polymers 0.000 description 4
- 239000010409 thin film Substances 0.000 description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 3
- ROGIWVXWXZRRMZ-UHFFFAOYSA-N 2-methylbuta-1,3-diene;styrene Chemical compound CC(=C)C=C.C=CC1=CC=CC=C1 ROGIWVXWXZRRMZ-UHFFFAOYSA-N 0.000 description 3
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 3
- 229920001634 Copolyester Polymers 0.000 description 3
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- 150000001252 acrylic acid derivatives Chemical class 0.000 description 3
- 150000001408 amides Chemical class 0.000 description 3
- 239000012736 aqueous medium Substances 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 239000001768 carboxy methyl cellulose Substances 0.000 description 3
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 3
- 150000007942 carboxylates Chemical group 0.000 description 3
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 150000001991 dicarboxylic acids Chemical class 0.000 description 3
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 239000000806 elastomer Substances 0.000 description 3
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 230000003301 hydrolyzing effect Effects 0.000 description 3
- ZIUHHBKFKCYYJD-UHFFFAOYSA-N n,n'-methylenebisacrylamide Chemical compound C=CC(=O)NCNC(=O)C=C ZIUHHBKFKCYYJD-UHFFFAOYSA-N 0.000 description 3
- 229920001296 polysiloxane Polymers 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 229920001059 synthetic polymer Polymers 0.000 description 3
- PMJHHCWVYXUKFD-SNAWJCMRSA-N (E)-1,3-pentadiene Chemical compound C\C=C\C=C PMJHHCWVYXUKFD-SNAWJCMRSA-N 0.000 description 2
- MYRTYDVEIRVNKP-UHFFFAOYSA-N 1,2-Divinylbenzene Chemical compound C=CC1=CC=CC=C1C=C MYRTYDVEIRVNKP-UHFFFAOYSA-N 0.000 description 2
- SDJHPPZKZZWAKF-UHFFFAOYSA-N 2,3-dimethylbuta-1,3-diene Chemical compound CC(=C)C(C)=C SDJHPPZKZZWAKF-UHFFFAOYSA-N 0.000 description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 229920000742 Cotton Polymers 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 206010021639 Incontinence Diseases 0.000 description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 2
- 229920000881 Modified starch Polymers 0.000 description 2
- 239000004368 Modified starch Substances 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 239000005062 Polybutadiene Substances 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 150000001336 alkenes Chemical class 0.000 description 2
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- WERYXYBDKMZEQL-UHFFFAOYSA-N butane-1,4-diol Chemical compound OCCCCO WERYXYBDKMZEQL-UHFFFAOYSA-N 0.000 description 2
- 150000003857 carboxamides Chemical class 0.000 description 2
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 description 2
- XMPZTFVPEKAKFH-UHFFFAOYSA-P ceric ammonium nitrate Chemical compound [NH4+].[NH4+].[Ce+4].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O XMPZTFVPEKAKFH-UHFFFAOYSA-P 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
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- 229910052739 hydrogen Inorganic materials 0.000 description 2
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- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
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- TWNIBLMWSKIRAT-VFUOTHLCSA-N levoglucosan Chemical group O[C@@H]1[C@@H](O)[C@H](O)[C@H]2CO[C@@H]1O2 TWNIBLMWSKIRAT-VFUOTHLCSA-N 0.000 description 2
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- BDJRBEYXGGNYIS-UHFFFAOYSA-N nonanedioic acid Chemical compound OC(=O)CCCCCCCC(O)=O BDJRBEYXGGNYIS-UHFFFAOYSA-N 0.000 description 2
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- YPFDHNVEDLHUCE-UHFFFAOYSA-N propane-1,3-diol Chemical compound OCCCO YPFDHNVEDLHUCE-UHFFFAOYSA-N 0.000 description 2
- 150000003839 salts Chemical group 0.000 description 2
- CXMXRPHRNRROMY-UHFFFAOYSA-N sebacic acid Chemical compound OC(=O)CCCCCCCCC(O)=O CXMXRPHRNRROMY-UHFFFAOYSA-N 0.000 description 2
- TYFQFVWCELRYAO-UHFFFAOYSA-N suberic acid Chemical compound OC(=O)CCCCCCC(O)=O TYFQFVWCELRYAO-UHFFFAOYSA-N 0.000 description 2
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- WEERVPDNCOGWJF-UHFFFAOYSA-N 1,4-bis(ethenyl)benzene Chemical compound C=CC1=CC=C(C=C)C=C1 WEERVPDNCOGWJF-UHFFFAOYSA-N 0.000 description 1
- VDNSZPNSUQRUMS-UHFFFAOYSA-N 1-cyclohexyl-4-ethenylbenzene Chemical compound C1=CC(C=C)=CC=C1C1CCCCC1 VDNSZPNSUQRUMS-UHFFFAOYSA-N 0.000 description 1
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- HGJDNBZIDQOMEU-UHFFFAOYSA-N 2-methyl-n,n-bis(prop-2-enyl)prop-2-enamide Chemical compound CC(=C)C(=O)N(CC=C)CC=C HGJDNBZIDQOMEU-UHFFFAOYSA-N 0.000 description 1
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- 239000001361 adipic acid Substances 0.000 description 1
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- 229910001413 alkali metal ion Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- XYLMUPLGERFSHI-UHFFFAOYSA-N alpha-Methylstyrene Chemical compound CC(=C)C1=CC=CC=C1 XYLMUPLGERFSHI-UHFFFAOYSA-N 0.000 description 1
- 125000003368 amide group Chemical group 0.000 description 1
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 1
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- JFCQEDHGNNZCLN-UHFFFAOYSA-N anhydrous glutaric acid Natural products OC(=O)CCCC(O)=O JFCQEDHGNNZCLN-UHFFFAOYSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- 230000001588 bifunctional effect Effects 0.000 description 1
- 210000001124 body fluid Anatomy 0.000 description 1
- 239000010839 body fluid Substances 0.000 description 1
- KDYFGRWQOYBRFD-NUQCWPJISA-N butanedioic acid Chemical compound O[14C](=O)CC[14C](O)=O KDYFGRWQOYBRFD-NUQCWPJISA-N 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 229920006184 cellulose methylcellulose Polymers 0.000 description 1
- 238000010382 chemical cross-linking Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- JAWGVVJVYSANRY-UHFFFAOYSA-N cobalt(3+) Chemical compound [Co+3] JAWGVVJVYSANRY-UHFFFAOYSA-N 0.000 description 1
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- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 150000001990 dicarboxylic acid derivatives Chemical class 0.000 description 1
- SZXQTJUDPRGNJN-UHFFFAOYSA-N dipropylene glycol Chemical compound OCCCOCCCO SZXQTJUDPRGNJN-UHFFFAOYSA-N 0.000 description 1
- 239000012990 dithiocarbamate Substances 0.000 description 1
- 238000010981 drying operation Methods 0.000 description 1
- 239000003995 emulsifying agent Substances 0.000 description 1
- 230000032050 esterification Effects 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- 238000007765 extrusion coating Methods 0.000 description 1
- IMBKASBLAKCLEM-UHFFFAOYSA-L ferrous ammonium sulfate (anhydrous) Chemical compound [NH4+].[NH4+].[Fe+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O IMBKASBLAKCLEM-UHFFFAOYSA-L 0.000 description 1
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- 239000006260 foam Substances 0.000 description 1
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000007863 gel particle Substances 0.000 description 1
- 229920000159 gelatin Polymers 0.000 description 1
- 239000008273 gelatin Substances 0.000 description 1
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- 239000011976 maleic acid Substances 0.000 description 1
- FQPSGWSUVKBHSU-UHFFFAOYSA-N methacrylamide Chemical compound CC(=C)C(N)=O FQPSGWSUVKBHSU-UHFFFAOYSA-N 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- DYUWTXWIYMHBQS-UHFFFAOYSA-N n-prop-2-enylprop-2-en-1-amine Chemical compound C=CCNCC=C DYUWTXWIYMHBQS-UHFFFAOYSA-N 0.000 description 1
- 229920003052 natural elastomer Polymers 0.000 description 1
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- PNJWIWWMYCMZRO-UHFFFAOYSA-N pent‐4‐en‐2‐one Natural products CC(=O)CC=C PNJWIWWMYCMZRO-UHFFFAOYSA-N 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
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- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
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- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
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- 229940116351 sebacate Drugs 0.000 description 1
- CXMXRPHRNRROMY-UHFFFAOYSA-L sebacate(2-) Chemical compound [O-]C(=O)CCCCCCCCC([O-])=O CXMXRPHRNRROMY-UHFFFAOYSA-L 0.000 description 1
- 210000002966 serum Anatomy 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 1
- 238000006277 sulfonation reaction Methods 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 239000005061 synthetic rubber Substances 0.000 description 1
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
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- 150000003672 ureas Chemical group 0.000 description 1
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- 150000003751 zinc Chemical class 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
-
- 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
- A61L15/24—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
- C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/22—Mixtures comprising a continuous polymer matrix in which are dispersed crosslinked particles of another polymer
Abstract
A flexible non-disintegrative absorbent product comprising a water- insoluble substantially non-swelling matrix of an thermoplastic-elastomeric or thermoplastic polymer bearing a uniformly dispersed particulate water- insoluble water-swellable organic polymer absorbent may be prepared by extrusion or solvent casting.
Description
SPECIFICATION
Absorbent products, processes & compositions
The present invention relates in general to non-disintegrative aqueous-fluid-absorbent products, processes
and compositions.
Background of the invention
Retention and or removal of water or aqueous liquids, particularly body fluids, are frequently accomplished by use of absorbent bearing materials and articles manufactured therefrom. Representative
articles include diapers, incontinence pads, sanitary napkins, bibs, wound dressings and the like. Generally, absorption is achieved by use of celiulosic and modified cellulose materials. Where the intended use
contemplates absorption of relatively large volumes of liquids such as diapers, sanitary napkins and the like,
the cellulosic materials are in the form of fluff or batting. For these uses especially, there are teachings in the literature for distributing particulate materials, sometimes referred to in the art as superabsorbents, throughout the batting or in certain areas thereof.The settling and bunching of the powder or particulate
matter encountered during shipping and storage have rendered these modifications qf little value in actual ;practice. Also found in the art are teachings for modifying the fibers in the batting to greatly increase their
absorbency. These modifications have not avoided the need for a batting which are inherently bulky. Free
films of absorbent polymers have been described but they are generally stiff, non-flexible and frequently frangible. Some films have been reported which are flexible but methods for the production of these films
employ aqueous medium either during or prior to extrusion with subsequent removal of water and do not
constitute convenient or practical manufacturing operations where time-consuming drying operations
necessary for removal of water are sought to be avoided.Absorbents have been distributed in latex but these films are also subject to similar manufacturing drawbacks. Very thin films of absorbent have been
coated onto cellulosicfibrous backings which while operable when contained such as in a diaper with topsheet and backsheet are subject to disintegration when not contained. Additionally, absorbents have
been incorporated in a foam matrix which may be useful for some applications but are not applicable for thin films or filaments. Although some suggestion has been made of water-insoluble polymeric sheet material
broadly as support for absorbent, no actual product is reported or known to be available.
Summary ofthe Invention
According to the present invention, there has been devised an aqueous-fluid-absorbent non-disintegrative
product which comprises a water-insoluble substantially non-swelling matrix of a elastomeric or thermoplastic polymer having at least partially imbedded therein, particulate water-insoluble but water-swellable organic polymer absorbent. By "water" as herein employed is meant aqueous fluids or
liquids and is intended to include such fluids as saline, serum, blood, mucous as well as other aqueous solutions or dispersions. The matrix, preferably of thermoplastic-elastomeric polymer or of thermoplastic polymer as subsequently defined, is insoluble and substantially non-swellable in aqueous systems and resistant to disintegration when wet.The absorbent is selected from organic polymers which are insoluble in water but which are swellable and which absorb many times their own weight of water or aqueous fluid. The organic polymer absorbents may be completely synthetic or may be selected from modified natural molecules, especially modified polysaccharide as hereinafter more fully described.
The product is flexible and if of thermoplastic-elastomeric or elastomeric polymer as matrix, also elastic, is
resistant to disintegration when wet, is manufactured in the absence of water, can be made very thin while still being highly absorbent, can be self-supporting or be a coating, can be made in many forms and/or shapes. The forms include film, monofilament, sheet, rope, tubing, etc. and as coating on a substrate, i.e., a supported film.
. The product may be prepared by the several procedures which are used in the manufacture of films, filaments and the like. The matrix polymer and the polymer absorbent comprise novel compositions suitable in certain of the methods of preparation and these compositions as well as the use of these compositions in preparing the products constitute an aspect of the present invention.
The absorbent product has numerous applications and is adaptable for use in protective coverings, sanitary napkins, wound dressings, diapers, bed pads, incontinence pads, packaging materials, agricultural blankets and the like. Certain articles which may be prepared employing the novel absorbent bearing polymer products also constitute an aspect of the present invention.
Brief description of the drawings
Figure I is a perspective view of an absorbent product in the form of a film and having absorbent dispersed throughout.
Figure 2 is a partial perspective view of an absorbent product in the form of a film with absorbent on one surface of the film.
Figure 3 is a partial sectional elevation taken along 3-3 in Figure 1.
Figure 4 is a partial sectional elevation taken along 4-4 in Figure 2.
Figure 5 is an enlarged partial sectional view showing an embodiment of the invention when the absorbent product is in the form of a monofilament.
Figure 6 is a partial sectional view showing an elongated core coated with the absorbent product.
Figure 7 is a perspective view of a diaper employing the absorbent product.
Figure 8 is a view of a tampon made of the absorbent product.
Description of the preferred embodiments
The absorbent product of the present invention has particulate water-insoluble but water-swellable organic polymer absorbent dispersed on the surface or throughout a water-insoluble substantially non-swelling matrix. In the preferred embodiments, the particles are dispersed in a manner such that the absorbent is partially imbedded in the matrix. By "partially imbedded" is meant that most of the particles of the organic polymer absorbent have a portion of the particle surface exposed or protruding above at least one surface of the matrix. Although some individual particles may be completely imbedded, they are generally in a contiguous relationship to particles which are exposed to a surface.In one embodiment of the
present invention the particles are dispersed throughout the matrix so that the particles are distributed within the matrix and are exposed to all surfaces of the matrix; in another embodiment, the particles are distributed on one surface of the matrix.
The foregoing may be better understood by reference to the drawings. Figures 1 and 3 show a product in the form of a film 11 in which the absorbent particles 13 is dispersed throughout the matrix 12. It can be seen from the area "X" in Figure 1, representing the underside of the film, that there is absorbent exposed on the
underside as well as on the top surface. Figures 2 and 4 show a product in the form of a film 11 a in which the absorbent 13 is on one surface of matrix 12. The area "Yin Figure 2 shows no absorbent exposed on the underside surface. Figure 5 illustrates absorbent dispersed throughout the matrix when the product is a monofilament 15 or a single strand rope. Figure 6 illustrates a coated article 16 with product in the form of a coating on a core substrate 17.
The particulate absorbent materials are non-fibrous substances in the form of fine, discrete particles which cannot be formed into a fabric web. The particles can have various shapes such as spherical, rounded,
angular, acicular, irregular, fragmented and the like. They range in size from about 1 micron to as much as 2 x
104 microns in diameter or cross-section (largest dimension when not spherical), and are selected from those materials which are generally considered powders and those which are non-pulverous particulate
matter. The expression, "powder" is employed to designate particles which are particle size of from about 1 to about 103 microns.
When the particulate materials are dispersed throughout and imbedded in the matrix they are preferably
in the form of a powder. When employed in the form of powder and dispersed throughout, the presence of the particles is not always readily apparent; the film or filament oftentimes appears as a smooth film of the
matrix polymer. In the embodiment in which the absorbent is borne on one surface of the film, the particles are preferably non-pulverous. The approximate shape and geometry of the particles are retained when the
material swells to provide for the binding of the fluid therein.
The matrix is of an elastomeric or thermoplastic polymer and preferably assumes a shape achievable by extrusion or in the case of an elastomeric polymer also be solvent casting. Thus, it may be in the form of a film, sheet, filament, wire, rope, tube and the like. Since one of the advantages of the present invention is the
rendering available of a very thin material of high absorption capacity which is highly flexible, and in the case of a thermoplastic-elastomeric matrix, also highly elastic, the preferred embodiments of the present
invention contemplate use of thin film or fine monofilamentas matrix. The matrix may have a thickness
ranging from about 1 mil to about 60 mils. The thickness of the film is contemplated generally to be less than about 10 mils. Usually, it will be more than 1 mil, preferably in the range of about 2.5 to 5 mils.When the
product is in the form of a filament or rope, the cross-sectional dimension may be from about 5 to about 60
mils. The expression "filament" or "monofilament" as herein employed is also meant a monofilament wire or rope without regard to the cross-sectional dimensions. It is intended to connote a single strand which is
not twisted or braided. When the product is in the form of a coating on a substrate, the dimensions may be similar to those of unsupported film but generally will be thinner.
The product has a capacity to absorb water or aqueous fluid in an amount of at least 3 times, preferably from about 15 to 40 times or more of the weight of the absorbent in the product. Since the absorptive capacity of the product is dependent on the amount of absorbent in the product, the absorptive capacity of the product depends on the density or on the weight of the absorbent incorporated into a given volume of the matrix. The particulate absorbent material is used in the product in the range of from about 5 to 200 parts, preferably from about 50 to 100 parts, for every 100 parts by weight of the matrix polymer. The product efficiently absorbs water and aqueous fluids while retaining flexibility or elasticity and flexibility, depending on the matrix polymer and is resistant to loss of water when subject two pressure.
The particulate absorbent materials to be dispersed in the matrix are organic polymers which may be wholly synthetic organic polymers or which may be modified polysaccharides. In these absorbent polymers, hydrophilic groups constitute at least 25 percent and up to about 72 percent of their molecular structure and the polymeric network has been lightly cross-linked to introduce a limited water-insolubility into the molecule. Suitable water-insoluble materials have a minimum average molecular weight per cross-linkage of about 13,000 and a maximum molecular weight per cross-linkage of about 276,000. These materials are frequently spoken of in the art as "hydrogels" or "hydrocolloid polymers," and further as "superabsor bents." The preferred polymers have an acrylate group in their molecular structure.They may be completely synthetic acrylate polymers or acrylate modified polysaccharides, e.g., acrylate modified starch or acrylate modified cellulose. "Acrylate polymers" or "polyacrylate" as herein employed embrace not only acrylate salts but also those in which a portion of the hydrophilic group is acrylamide, acrylic acid or acrylate ester.
Alternatively, the hydrophilicity may be supplied by a different type of hydrophilic group such as sulfonate, oxide, etc., or by a different type of polymer as hereinafter detailed. Carboxymethylcellulose after cross-linking is also within a scope of suitable absorbents. The absorbent is typically a cross-linked natural or synthetic polymer which without the cross-linking would be water-soluble but which has been lightly cross-linked in ways known in polymer syntheses. The preferred absorbents are cross-linked polymers belonging to one of the following: completely synthetic acrylate polymer, acrylate modified starch, acrylate modified cellulose, and cross-linked carboxymethylcellulose.
Considering first Considering first the preparation of the completely synthetic absorbents, it is immaterial in the present invention whether the polymers here to be employed be prepared by supplying appropriate monomer or monomers and thereafter polymerizing, or by polymerizing and thereafter modifying a part of the resulting polymer with recurring moieties. Thus, the polymers may be prepared by cross-linking a preformed water-soluble straight chain polymer, by polymerizing an appropriate monomer or monomer and co-monomer and effecting both polymerization and cross-linking, or by incorporating an appropriate group in the polymer structure after completion of the polymerization. An example of the latter is sulfonation after polymerization to obtain polymers bearing sulfonic moieties.Moreover, where it is desired to have the salt form of the carboxylic or sulfonic group, the polymer may be first prepared as an acid, ester, amide or nitrile and the product hydrolyzed in whole or in part.
The preferred of the synthetic absorbents are the acrylate type absorbent which includes not only the acrylate salts and acids but also those which have been represented in the literature, e.g., U.S. 3,686,024, by the following formula:
where A is an alkali metal ion such as sodium or potassium, or hydrogen, n is 0.5 to about 0.9, 1-n defines the
extent of hydrolysis, and z is the number of mer units between cross-links.
The latter type of acrylate absorbent may be prepared by polymerizing an about 2 to 20 weight percent
aqueous solution of acrylamide with from about 0.005 to 0.5 mole percent (based on acrylamide) of a
difunctional organic cross-linker such as N, N'-methylenebisacrylamide soluble in the aqueous monomer system in the presence of free radical catalysts to obtain a water-swellable cross-linked polyacrylamide, and thereafter partially hydrolyzing in aqueous alkali to obtain a cross-linked polymer having both carboxamide and alkali metal carboxylate groups as more fully described in U.S. patent 3,247,171. Alternatively, a linear
polyacrylamide may be cross-linked with a cross-linking compound such as N, N'-methylenebisacrylamide, 1,4-divinylbenzene, diallylamine, N,N-diallyl-methacrylamide and the like, and thereafter hydrolyzing.
A polymer having both carboxamide and carboxylate group also may be made by copolymerizing acrylamide and acrylic acid alkali metal salt in the presence of cross-linking monomer such as
N,N-methylenebisacrylamide in the presence of catalyst system as equal parts of ammonium persulfate and ss-dimethylaminopropionitrile, also described in the aforesaid patent. Theformertype may be prepared by subjecting a mixture of a monovalent cation salt of acrylic acid in water to the influence of high energy ionizing radiation cross-linking as more particularly described in U.S. patent 3,229,769, or subjecting it to chemical cross-linking as described in British 719,330.A number of suitable acrylate absorbents are available commercially, such as PERMASORB (National Starch and Chemical), SANWET (Sanyo), "5388" designation (Goodrich), AQUA-KEEP (Mitsubishi), and is also obtainable from The Dow Chemical Company.
Another type of completely synthetic absorbent is a cross-linked poly(alkylene oxide) of molecular weight of at least 100,000 which may be prepared by contacting poly(alkylene oxide) with a suitable cross-linking 'agent in the presence of a free radical catalyst in a liquid medium containing solvent-nonsolvent mixture for poly(alkylene oxide) wherein the nonsolvent portion constitutes at least 35 percent by weight of the liquid medium at a temperature sufficiently high to effect cross-linking as more fully described in U.S. patent 3,956,224. Alternatively, poly(alkylene oxide) may be cross-linked by ionizing irradiation as described in U.S.
patent 3,264,202, or co-cross-linked with at least one other water-soluble polymer by exposing aqueous systems of the polymers to high energy irradiation to produce cross-linked water-insoluble absorbent polymers as more fully described in U.S. patent 3,957,605 and 3,898,143.
Still another type of completely synthetic polymer absorbent is cross-linked polystyrene sulfonates prepared by known procedures, e.g., by copolymerizing styrene with a non-conjugated divinyl compound such as divinylbenzene in the presence of a polymerization catalyst such as benzoyl peroxide, preferably in the presence of a suspension stabilizer such as gelatin or polyvinyl alcohol, to produce a polymer which is then sulfonated by heating in the presence of concentrated sulfuric acid at a temperature of about 100"C.
Other suitable completely synthetic polymer absorbents include the poly(N-vinylpyrrolidone) type described in U.S. 3,669,103, polyurethane hydrogels described in U.S. 3,939,105 and 3,939,123. Still other suitable absorbents are represented by those named in U.S. 3,669,103,3,966,679 and 4,102,340.
Another type of particulate absorbent material suitable for the present purposes is of polysaccharides modified by having grafted thereon hydrophilic chains. By "hydrophilic chains" is meant a polymer chain obtained from monomers which have a water-soluble group or which become water-soluble on hydrolysis, e.g., carboxyl, sulfonic hydroxyl, amide, amino, quaternary ammonium and hydrolysis products. Representatives of such modified polysaccharides are described in U.S. 4,076,663. Preferred polysaccharide have hydrophilic chains containing a carboxylate group alone or together with a carboxylic or carbamide group attached to starch or cellulose backbone. The modified polysaccharides are sometimes referred to in the literature as starch or cellulose graft copolymers; the preferred modified graft copolymers are polysaccharide acrylates, or starch or cellulose acrylates.In these polysaccharide acrylates, the hydrophilic chain is attached to the backbone of the cellulose or starch molecule through a carbon linkage. Thus, a modified cellulose may be represented by the formula
wherein L represents a hydrophilic chain of the general formula
wherein
represents acid, ester, alkali metal or ammonium salt, or amide groups, each R independently is hydrogen or lower alkyl, r is an integer of 0 to about 5000 and s is an integer of from 0 to about 5000, and r plus s is at least 500. A starch graft copolymer would be similar but would have a starch backbone.These polysaccharide acrylates may be prepared, for example by polymerizing an appropriate polysaccharide with acrylonitrile or methacrylonitrile, with methyl or ethyl acrylate, with acrylic or methacrylic acid, or with acrylamide or methacrylamide, and thereafter hydrolyzing the resulting polymer in whole or in part with aqueous alkali.
Alternatively, the polymer containing the carboxylate group may be prepared by polymerizing the alkali metal salt of acrylic or methacrylic acid. The procedures for carrying out graft-copolymerization of olefinically unsaturated chains onto cellulose and starch are well known in the art. Thus, grafting of the hydrophilic material onto a starch or cellulose backbone can be accomplished simultaneously with the formation of the hydrophilic polymeric material in an aqueous medium, because the peroxide catalyst used to copolymerize the various monomers forms a redox catalyst system in the combination with a reducing agent and the like and thus also serves to effect chain transfer onto the starch or cellulose backbone. Suitable reducing agents for this purpdse are ceric ion, ferrous ion, cobaltic ion, (NH4)2S208,cuprous ion, and the like.
The desired ions can be supplied in the form of salts such as ceric ammonium nitrate, ferrous ammonium sulfate, and the like. Graft copolymerization of olefinically-unsaturated chains can also be effected by irradiation (ultraviolet-, gamma, or X-radiation) or by heating in an aqueous medium in the presence of an emulsifier.
Powdered starch or cellulose fibers or pulp can be slurried in water containing a graft copolymerization catalyst system and the monomer or monomers added to the slurry and polymerized in situ at ambient temperature or above depending on the catalyst employed. In this manner a portion of the formed hydrophilic polymer may also be physically entrapped into the polysaccharide backbone material during the polymerization process. The preparation of suitable starting materials for practicing the present invention is also illustrated in U.S. Patent Nos. 2,922,768, 3,256,372,3,661,815, 3,935,099,4,028,290, 4,076,663 and 4,105,033. Suitable starch polyacrylates are available commercially such as SGP 502S (General Mills or
Henkel) and STASORB (A.E.Staley).
Suitable polysaccharides acrylates are those in which the hydrophilic chain loading on the backbone is within the range of about 10 percent by weight to about 90 percent by weight, preferably about 40 to about 80 percent by weight of the graft co-polymer. The polymers produced are dried at atmosphere pressure to drive off the water to produce a relatively stiff and brittle material which may be comminuted into powder of particle size of at least 1 micron. Preferably, the particles are no less than about 50 microns and no greater than about 1000 microns. Most preferably they are in the range of about 70 to about 325 microns.
A fourth type of absorbent suitable in the present invention is cross-linked carboxymethylcellulose (CMC).
Suitable cross-linked carboxymethylcellulosa are those which may be prepared by heat treatment or wet
cross-linking of the sodium salt of carboxymethylcellulose having from about 0.5 to about 1 carboxymethyl
group for each anhydroglucose unit. In wet cross-linking, reagents bifunctional with respect to cellulose such
as epichlorohydrin may be employed.
A representative method for the preparation of absorbent of the class cross-linked carboxymethylcellulose
is heating finely divided particulate form of water-soluble alkali metal salt of carboxymethylcellulose having
from about 0.5 to about 1 carboxymethyl group for each anhydroglucose unit to a temperature between
about 1300C and about 210 C, generally from a few minutes to several hours to obtain products which retain
their physical appearance when dry but when suspended in water show reduced solubility and a new
capacity of absorbing water to form swollen gel particles as more fully described in U.S. 2,639,239. The particle, if not of desired size, may be-comminuted to powder of particle size preferably in the range of
about 50 microns to 1000 microns.Suitable cross-linked carboxymethylcellulose are available as
AOUASORB from Hercules.
The matrix in the absorbent product of the present invention comprises an elastomer or a thermoplastic
polymer. The elastomer is preferably a thermoplastic-elastomeric block copolymer but also may be natural
rubber, synthetic rubbers such as styrene-butadiene rubber, and the like which are elastic and which have glass transition temperature below about -10"C. The thermoplastic polymer preferably is a co-polyester but
also may be polypropylene, polyethylene, etc. The matrix also may be of an alloy of certain elastomers and
thermoplastic polymers as subsequently described.
The thermoplastic-elastomeric block copolymers are those-having a thermoplastic block conventionally
designated as A blocks and rubbery blocks conventionally designated as B blocks. One suitable group of
block copolymer include those having thermoplastic endblocks and rubbery midblocks and designated as
A-B-A block copolymers. The expression "A-B-A" block copolymer is intended to embrace all variations of
block copolymers with rubbery midblocks and thermoplastic endblocks. Thus, it is intended to embrace
copolymers sometimes designated A-B-C block copolymer in which C is also a thermoplastic endblock but of
a different polymer than A. It is also intended to embrace linear, branched and radial block copolymers.The
radial block copolymers may be designated (A-BinX wherein X is a polyfunctional atom or molecule and in
which each (A-B) radiates from X in a way that A is an endblock. Another suitable group of block copolymers
include those in which B forms one endblock rather than a midblock and which are sometimes referred to as
"A-B" or "simple" block copolymers. The expression "block copolymer" without qualification is intended to
embrace both A-B-A and A-B type of copolymers.
The thermoplastic "A" block is generally a polymer of alkenylarenes, preferably of styrene or styrene
homologs and analogs such as a-methylstyrene, 5-tertiary-butyl-styrene, 4-methylstyrene, 3,5- diethylstyrene, 3,5-di-n-butylstyrene, 4-(4-phenyl-n-butyl)styrene, 2-ethyl-4-benzylstyrene, 4- cyclohexylstyrene, 4-n-propylstyrene vinyltoluene and the like.
The rubbery "B" block is a polymer of a conjugated lower aliphatic diene of from 4 to about 6 carbon
atoms or of a lower alkene of from 2 to about 6 carbon atoms. Suitable conjugated dienes include butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethylbutadiene and the like. The preferred dienes are
butadiene and isoprene. Suitable alkenes include ethylene, butylene, propylene and the like.
In the radial block copolymer, (A-B+nX, X may be an organic or inorganic polyfunctional atom or molecule
and n is an integer having the same value as the functional group originally present in X. It is usually at least
3 and is frequently 4 or 5 but is not limited thereto. In addition, it embraces a more complex radial block
copolymer system disclosed in the article, "New Rubber is Backed by Stars," appearing in Chemical Week,
June 11,1975, page 35.
Suitable thermoplastic rubber block copolymers are prepared by stepwise solution polymerization of the
components. The preparations and properties of block copolymers are amply described in the literature such
as, for example, "Thermoplastic Rubber (A-B-A block Copolymers) in Adhesives" by J.T. Harlan et al., in
',Handbook of Adhesives" edited by Irving Skeist, Van Nostrand Reinhold Co., New York, Second Edition
(1977), pages 304-330; "Rubber-Related Polymers, I. Thermoplastic Elastomers" by W. R. Hendricks et al, in
"Rubber Technology" edited by Maurice Morton, Van Nostrand Reinhold Co., New York (1973), pages
515-533; and U.S. Patents 3,321,635; 3,519,585; 3,787,531; and 3,281,383; andforA-B blockcopolymers, U.S. Patents 3,519,585 and 3,787,531.
In the suitable block copolymers, the individual "A" block portion has a number average molecular weight
of at least 6,000, preferably in the range of from about 8,000 to 30,000, and the "B" block portion has a
number average molecular weight preferably in the range of from about 45,000 to about 180,000. The "A" blocks constitute from about 5 to about 50 percent, preferably about 10 to about 30 perent by weight of the
block copolymer. The number average molecular weight of the block copolymer is preferably in the range of
about 75,000 to 200,000 for linear copolymers and preferably in the range of about 125,000 to 400,000 for
radial copolymers.
When the "A" block is polystyrene and the "B" block is a polymer of butadiene, the polymer may be
referred to as an S-B-S or S-B polymer, and when the "A" block is a styrene polymer and the "B" block is an
isoprene polymer, the polymer may be referred to as an S-I-S or S-l polymer. Many of the block copolymers
are obtainable commercially under trade names such as Kraton 1102 and 1107 (both linear Shell Chemical Co.), Solprene 418 and 420 (both radial), and Solprene 311X and 1205 (both simple; Phillips Petroleum Co.).
Embraced within the scope of thermoplastic elastomericA-B-A or A-B block copolymers are certain alloys of A-B-A or A-B block copolymers as above defined and co-polyesters, as hereinafter defined. The alloys intended to be included within the scope of the thermoplastic-elastomeric A-B-A or A-B block copolymer designation are those having essentially elastic properties and in which the A-B-A or A-B block copolymer is at least about 55 percent by weight and the co-polyester is correspondingly no greater than about 45 percent by weight.
The thermoplastic co-polyester is essentially a polymer of at least two identifiable ester units which may be represented by the formulas
wherein X and X' are nuclei of dicarboxylic acids and Y andY' are nuclei of aliphatic diols. The different ester units may arise from the condensation of (a) two different acids with the same diol, (b) two different diols with the same acid, or, (c) two different acids and two different diols. By "co-polyesters" is meant to include
random and segmented co-polyesters as well as copolyester with alternating units formed by copolymerization. By "random" is meant that the ester units are not usually in a definite pattern. By "segmented" is meant there is a polymer block of a given ester unit joined to a polymer block of another ester unit through an ester linkage.Generally, one ester unit of the co-polyester is highly crystalline and one substantially less crystalline or even non-crystalline.
Among the aromatic and aliphatic dicarboxylic acids suitable in co-polyester are terephthalic acid, isophthalic acid, oxalic acid, maleic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid and the like.
Aiiphatic diols used in the polyesters include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butylene glycol, tetramethylene glycol, trimethylene glycol, and the like. Preferred aliphatic diols are straight chain alkylene diols having from 2 to 4 carbon atoms.
As representative co-polyesters may be mentioned the following: Poly(ethylene terephthalate-co-ethylene azelate), poly(ethylene terephthalate-co-butylene adipate), poly(ethylene terephthalate-co-1 ,2-propylene terephthalate), poly(butylene terephthalate-co-butylene isophthalate), poly(ethylene terephthalate-coethylene sebacate), poly(ethylene terephthalate-co-tetramethylene terephthalate), poly(ethylene terephtha
late-co-ethylene adipate), poly(ethylene terephthalate-co-trimethylene terephthalate), and the like, including polyesters described on pages 77-80 of "Encyclopedia of Polymers, Science and Technology," Vol. Xl, John Wiley & Sons (1977). Random co-polyesters frequently may be identified by the relative amounts of component diols and acids as in U.S. patent 3,699,189.Such polyesters are also within the scope of suitable matrix polymer.
The co-polyesters normally possess a thermal softening temperature below about 225"C (437"F). The preferred co-polyesters have an extrusion temperature within the range from about 325" to about 425"F.
Suitable co-polyesters may be -characterized by a torque property which can be measured by working in a recording torque dynamometer (Plasti-Corderw EPL-V750 manufactured by C. W. Brabender Co., Hackensack, N. J.). When worked at 75 r.p.m. at 420"F using a REE 6 mixing head, suitable co-polyesters will exhibit a torque value of less than about 1000 meter grams, preferably in the range of from about 200 to about 700 meter grams at this temperature. These values may be converted to poises by employing the following formula
torque x 388 = poise r.p.m.
Thus, when expressed in poises, the esters should show torque properties of less than about 5200 poises, preferably about 1000 to 3600 poises. Generally the co-polyesters having the foregoing suitable properties are in the number average molecular weight range of about 20,000 to 200,000, preferably about 30,000 to 75,000.
Co-polyesters may be made by conventional condensation polymerization procedures such as esterification of dicarboxylic acids or acid derivatives, e.g., esters or acid halides with diols, usually with temperatures in the range of from about 1 500C to 250"C, but sometimes as high as 280"C with the formation of a co-polyester polymer. The reaction is usually carried out in the presence of excess diol to compensate for the loss of diol during co-distillation with liberated water of reaction; it may be carried out in the presence of catalysts.
Another method for carrying out the reaction is ester interchange employing diols with dicarboxylic acid
diesters or employing dicarboxylic acids with diol diesters. These and other methods may be found in the art
including "Encyclopedia of Polymer Science and Technology," of Polymer Science and Technology," Vol. II,
pages 88-113.
Segmented co-polyesters useful as matrix materials also may be prepared employing similar procedures
applied in a step-wise manner. In one representative procedure, a low molecular weight alkyl diester of one
or more dicarboxylic acid is heated with an appropriate long chain and excess short chain diol in the
presence of catalyst at about 1500 to 2000 with the distillation of the low molecular weight alcohol formed in
the, interchange. Heating is continued until the alcohol evolution is complete to obtain a very low m.olecular weight prepolymer which can be converted to high molecular weight segmented co-polyester by heating
the prepolymer with a long chain diol and distilling off excess short chain diol preferably at reduced
pressures and elevated temperatures in the presence of antioxidants.Representative preparations may be
found in U.S. patents 3,832,314 and 3,932,326. Suitable polymers are also available commercially underVPE
designations from Goodyear Tire & Rubber Company, under KODARs designations from Eastman Chemical
Company and DYVAX designations from El. du Pont de Nemours & Co. Inc.
Embraced within the scope of co-polyesters are certain alloys of co-polyester and A-B-A or A-B block
polymer. In such alloys being those having essentially plastic film forming properties block copolymer is in
the range of about 75,000 to 200,000 for linear copolymers and 125,000 to 400,000 for radial copolymers. The
alloys intended to be within the scope of copolyester are those in which the co-polyester component is the
major component of from 55 to 95 percent by weight and the block copolymer component is the minor
component of from 45 to 5 percent by weight.
The absorbent product of the present invention may be prepared by several methods none of which
necessitate the use of an aqueous environment, thus eliminating the need for extended drying procedures.
The preferred method may depend of the particular absorbent employed or whether it is desired to have the
absorbent on one surface only.
When the absorbent is stable to the extrusion temperature of the matrix polymer and/or when the
particulate absorbent is to be dispersed throughout the matrix, rather than on one surface, the product may
be prepared by extrusion. Some of the absorbents which are extrudable are polyacrylate as previously
defined, sulfonated polystyrene, poly(alkylene oxide), and the like.
In employing the extrusion method, the matrix polymer and the absorbent polymer are thoroughly
blended together and extruded. Preblending is highly desirable if there is to be a high loading of the
absorbent. If the level of absorbent to be dispersed is low, i.e., about 5 to 15 parts by weight per 100 parts by
weight of matrix polymer, the components may be fed directly into the extruder without preblending.
However, it is preferred that the absorbent polymer and the matrix polymer be preblended with heating to a
uniform dispersion of the particulate absorbent in the molten matrix polymer, and the resulting uniform
blend after cooling be pelletized, crushed, flaked or otherwise reduced to a size suitable for feeding into an
extruder or the molten blend be fed directly into the extruder and the extrusion carried out to obtain a
non-disintegrative absorbent product comprising a water-insoluble substantially non-swelling matrix of a
thermoplastic or a thermoplastic-elastomeric polymer having dispersed throughout, particulate, water
insoluble but water-swellable organic polymer absorbent in the form of a film, filament, tubing or other
extrudable shape. In this method, the absorbent is preferably in the form of a powder, i.e., particle size of 103
microns in diameter or less.The preblending preferably may be carried out in the temperature range of from
about 150"C to 275"F. When the matrix polymer is thermoplastic, the range is about 225 to 275"F. The
extrusion is preferably carried out in the temperature range of from about 300"F to about 450"F. When the
extrusion is of a thermoplastic polymer, it has been found that although not essential, the addition of a minor
amount, e.g., from about 5 to about 10 parts by weight per 100 parts be weight of thermoplastic matrix
polymer, of an A-B-A block polymer is desirable to facilitate extrusion. The extrusion method is particularly
suitable for obtaining non-disintegrative absorbent product in the form of very thin films and monofila
ments.The product will have absorbent dispersed throughout as seen in Figures 1,3 and 5 of the drawings.
' The extrudable compositions which are preferably formed by pre-blending and comprising (a) thermoplastic-elastomeric matrix polymer or thermoplastic matrix polymer and (b) particulate polymer
absorbent constitute an aspect of the present invention. The composition may include minor amounts of rnatenals generally added to extrudable film forming compositions. Representative of such additives are
antioxidants such as 2,5-ditertiary-amylhydroquinone, zinc salts of alkyl dithiocarbamates; fillers and
pigments such as zinc oxide, titanium dioxide, calcium carbonate, and the like. In addition to the
conventional additives, small amounts of wetting agents may be included which will facilitate initiation of
aqueous fluid uptake by the absorbent. In the compositions in which the matrix polymer component is
thermoplastic (without elastomeric properties), a very small amount, up to about 10 percent, of the
thermoplastic-elastomeric block copolymer (A-B-A or A-B block copolymer) described for the alloy
compositions may be included without significantly altering the properties of the plastic matrix polymer.
Generally, the extrudable compositions comprise from about 5 to about 200 parts of polymer absorbent per
100 parts by weight of matrix polymer.
Preferred extrudable compositions are those which comprise synthetic polyacrylates and a thermoplastic
elastomeric A-B-A or A-B block copolymer matrix polymer or a synthetic polyacrylate and a copolyester
matrix polymer. As previously indicated, the expression "acrylate" includes polymers which have any of acid ester, amide or salt acrylate groups or mixtures thereof. The compositions of polyacrylate and block copolymer comprise from about 5 to about 200 parts of acrylate polymer per 100 parts of A-B-A or A-B block copolymer, preferably from about 20 to 100 parts. The compositions of polyacrylate and co-polyester comprise from 5 to about 500 parts of acrylate polymer, preferably, about 50 to 150 parts, per 100 parts of co-polyester.
The extrudable composition also may be employed in a hot melt casting technique. Thus, instead of cooling the molten blend and pelletizing for extrusion, the molten composition may be cast to produce a free film, or a coating on a substrate.
Another method by which a product may be uniformly dispersed throughout the matrix is particularly suitable for the preparation of elastomeric film. This method contemplates a solvent casting composition in which the rubber or thermoplastic-elastomer, polymer absorbent and antioxidants are dispersed in an organic solvent. The composition is cast onto a suitable surface employing conventional methods, the solvent evaporated to obtain an elastic film having absorbent polymer uniformly dispersed throughout.
Suitable solvents for the casting compositions are generally aromatic or paraffin hydrocarbons especially, toluene, xylene, benzene, heptane and the like. The compositions usually also contain antioxidants.
Conventional antioxidants include zinc dibutyl dithiocarbamate, 2,5-diteriary-butylhydroquinone, 2,5- diteriaryamylhydroquinone and the like.
Absorbent products in which the particulate absorbent is to be supported by the matrix primarily on a surface may be prepared by a process in which the matrix is first formed and the absorbent incorporated thereon. This process is applicable in the preparation of the absorbent product regardless of the chemical nature of absorbent polymer employed.
One modification of this general procedure contemplates incorporation of the absorbent polymer substantially at the time of formation of the matrix. In this method, the matrix polymer is extruded into whatever shape is contemplated, generally, a film or a monofilament, and the absorbent is applied on the surface of the molten curtain or filament. The absorbent on contact becomes partially imbedded in the still molten surface and becomes permanently imbedded on cooling. The operation may be carried out by modification of the extrusion equipment in ways known in the art. For imbedding in a film, the particulate absorbent polymer may be spread or dusted on the film as it leaves the die. For incorporating on the surface of a filament, a similar procedure may be employed using a die adapter.
Another method employs a preformed matrix and the use of a solvent coating composition which has a solvent effect on the surface of the matrix allowing partial imbedding of the absorbent simultaneously with adhesion, and the effect made permanent by the passing of the material through drying ovens. In one of these modifications, a non-pressure sensitive adhesive composition is coated on the surface of an extruded film or filament and the absorbent applied on the surface of the solvent wetted film prior to passage through the ovens In such method, any organic solvent coatable adhesive composition may be employed. In a second modification of this general method, a pressure-sensitive coating adhesive composition is coated on the face of an extruded film or filament, the solvent removed from the coated film or filament and the absorbent applied to the surface.
The absorbent product prepared by any one of the foregoing methods, particularly the products in the shape of films, may be further modified to form a discontinuous planar surface. Such surface may be reticulated or may contain embossed patterns of protrusions and depressions. Reticulated films are of special value for superior rate of fluid uptake. Preparation of absorbent products of films with discontinuous surfaces may be carried out in accordance with procedures well known in the art.
The following examples illustrate the invention but are not to be construed as limiting:
Example I
An extrudable composition of 100 parts by weight of a styrene-isoprene-styrene (S-I-S) block copolymer (Kraton 1107) and 100 parts by weight of polyacrylate powder (Permasorb AG) are thoroughly blended at about 250"F and the resulting molten blend cooled, pelletized and the pellets extruded at about 350"F to form, a film 3 mils in thickness with absorbent dispersed throughout. The film product swells immediately on contact with water.
Example II An extrudable composition of 100 parts by weight of styrene-butadiene-styrene (S-B-S) block copolymer (Kraton 1102) and 40 parts by weight polyacrylate powder (Sanwet) are blended, pelletized and extruded as described in Example I to form a film 10 mils in thickness with the absorbent dispersed throughout. The film products absorbs water rapidly.
Example III An absorbent composition suitable for film formation by solvent casting and of the following formulation:
S-I-S rubber (Kraton 1107) 100 parts by weight
Starch polyacrylate (SPG 5025) 100 parts by weight
Zinc dibutyl dithiocarbamate 5 parts by weight 2,5-Ditertiary-butylhydroquinone 1 part by weight
Solids in toluene 50 percent
is prepared by solvating the rubber and antioxidants in toluene and thereafter stirring in the starch
polyacrylate absorbent. The composition is cast on a silicone liner at a dry coating weight of 2.0 ounces per square yard and the solvent thereafter evaporated to obtain absorbent film product having good absorptive
properties.
Example IV
A composition suitable for solvent casting of the following formulation:
S-I rubber (Solprene 311) 100 parts by weight
Polyacrylate (Permasorb-AG) 30 parts by weight
Zinc dibutyl dithiocarbamate 5 parts by weight
2,5-ditertiary-butylhydroquinone 1 part by weight
Solids in toluene 50 percent
is prepared by solvating the rubber and antioxidants in toluene and thereafter stirring in the polyacrylate
absorbent. The composition is cast on a silicone liner at a dry coating weight of 3.0 ounces per square yard
and the solvent then evaporated to obtain absorbent film product.
Example V
In a mannersimilarto that described in Examples III and IV, an absorbent film product of 3.0 mils is
obtained by casting the following film forming composition:
S-B-S rubber (Kraton 1102) 100 parts by weight
Cross-linked carboxymethylcellulose 20 parts by weight
Zinc dibutyl dithiocarbamate 5 parts by weight
2,5-ditertiary-butylhydroquinone 1 part by weight
Solids in toluene 50 percent
The film rapidly absorbs free water on contact.
Example Vl A 1 mil thermoplastic elastomeric film of S-I-S block copolymer(Kraton 1107) is solvent coated with the following pressure-sensitive adhesive formulation:
S-I-S rubber (Kraton 1107) 50 parts by weight
S-l rubber (Solprene 311) 50 parts by weight
Tackifier resin (Wing-tack 95) 80 parts by weight
Zinc dibutyl dithiocarbamate 2 parts by weight
2,5-ditertiary-butylhydroquinone 1 part by weight
The adhesive composition is applied in amounts sufficient to deposit the pressure-sensitive adhesive on the film at the rate of 1 ounce per square yard and the resulting coated film passed through drying ovens
maintained at 250"F. After the film is thoroughly dried, a cross-linked carboxymethylcellulose absorbent
(Permasorb 10, National Starch) is uniformly applied to the surface of the film to produce a non
disintegrative absorbent product having the absorbent uniformly distributed on one surface thereof. The
absorbent product on contact with an aqueous system shows immediate absorption of aqueous fluid.
(Wing-tack 95 is a predominantly polymerized piperylene-isoprene tackifier resin from Goodyear Tire & BR<
Rubber.)
Example VII
A 1 mil thermoplastic-elastomeric film of S-I-S block copolymer (Kraton 1107) is coated with the following adhesive formulation at 1 ounce per square yard:
S-I-S rubber (Kraton 1107) 100 parts per weight
Resin (Amoco 18-290) 75 parts by weight
Zinc dibutyl dithiocarbamate 2 parts by weight 2,5-ditertiary-butyl hydroquinone 1 part by weight
Solids in toluene 50 percent by weight (Amoco 18-290 is poly(a-methylstyrene) resin offered by Amoco Chemical Co.)
To the surface of the freshly coated film, particulate starch polyacrylate absorbent, (SGP 5025, General
Mills or Henkel), is applied in a substantially monomolecular layer and the resulting film passed through drying ovens (maintained at about 250"F) to remove the toluene solvent and to obtain an absorbent film product bearing absorbent on one major surface thereof. The resulting film shows immediate absorption when contacted with saline solution.
Example Vlil Radial S-I-S block copolymer is extruded at 350"F as a film and granular starch polyacrylate absorbent
(Stasorb, A. E. Staley Company) is applied on the surface of the molten curtain. The curtain is allowed to cool to obtain a non-disintegrative absorbent product bearing absorbent on one major surface thereof. The product shows good absorptive properties.
Example IX
The composition of Example I is prepared for extrusion and extruded to form a monofilament about 1 mil in diameter. The monofilament on contact with water absorbs water and forms a swollen rope.
Example X
An extrudable composition of 100 parts by weight of a poly(ethylene terephthalate-co-ethylene azelate) co-polyester (VPE 5571) and 40 parts of polyacrylate powder (Permasorb AG) are thoroughly blended at 350"F and the resulting molten blend cooled, pelletized and the pellets fed into the hopper of an extruder simultaneously with a minor amount of commercially available styrene-isoprene (S-I) block copolymer
(Solprene 311, Phillips Petroleum Company) and extruded at a temperature of about 350"F to form a film 5
mils in thickness having the absorbent dispersed throughout The film immediately swells when contacted with water at room temperature.
Example XI
In another operation, 75 parts by weight of VPE 5571,25 parts by weight of Solprene-311 and 50 parts by weight of Permasorb AG are thoroughly blended, pelletized extruded in a similar manner to form a film 3
mils in thickness having the absorbent uniformly dispersed throughout. The film absorbs water rapidly.
Example Xll In a still further similar operation, 100 parts of poly-(ethylene terephthalate-co-1 ,2-propylene terephtha
late) co-polyester (VPE 4709, Goodyear Tire & Rubber Company) and 40 parts of polyacrylate absorbent
(Sanwet, Sanyo Company) are blended together at about 350"F, the molten blend cooled, pelletized and
extruded silultaneously with about 5 parts of styrene-isoprene- styrene (S-I-S) block copolymer (Kraton 1107) to produce a 2 mil film having the polyacrylate absorbent dispersed throughout. The film swells immediately when contacted with aqueous saline solution.
Example Xlil In another similar operation, 100 parts of VPE-5571 and 2 parts of Permasorb AG are blended together with
heating, pelletized and extruded to produce a film bearing bsorbent uniformly dispersed throughout and
suitable for use in small absorbent bandages.
Example XIV
Cotton fabric is solvent coated with the following pressure-sensitive adhesive formulation:
Component Parts by weight
Kraton 1107 50
Solprene 311 50
Tackifier resin (Wingtack 95) 80
Zinc dibutyl dithiocarbamate 2
2,5-ditertiary butylhydroquinone 1 (Wingtack 95 is a predominantly polymerized piperylene and isoprene available from Goodyear Tire & BR<
Rubber)
The adhesive composition is applied in amount sufficient to deposit the pressure-sensitive adhesive on the fabric at the rate of 3 ounces per square yard and the resulting coated film passed through drying ovens maintained at about 300"F. After the coated fabric is thoroughly dried, a cross-linked carboxymethylcellulose absorbent (Aquasorb, Hercules) is uniformly applied to the surface of the film to produce a nondisintegrative absorbent product having the absorbent uniformly distributed on one surface thereof. The absorbent product on contact with an aqueous system shows immediate absorption of aqueous fluid.
Example XV
A 1 mil polyester (VPE 5571) film is coated with the following adhesive formulation:
Component Parts by weight
SIS rubber (Kraton 1107) 100
Resin (Amoco 18-290) 75
Zinc dibutyl dithiocarbamate 2
2,5-ditertiary-butylhydroquinone 1
Solids in toluene 50% (Amoco 18-290 is poly(a-methylstyrene) resin offered by Amoco Chemical Co.)
To the surface of the freshly coated film, particulate starch polyacrylate absorbent, (SGP 5025, General
Mills or Henkel), is applied in a substantially monomolecular layer and the resulting film passed through drying ovens (maintained at about 250"F) to remove the toluene solvent and to obtain an absorbent film product bearing absorbent on one major surface thereof. The resulting film shows immediate absorption when contacted with saline solution.
Example XVI
VPE 5571 is extruded at 350"F with the aid of about 5 percent by weight of Kraton 1107 to a film and granuiar starch polyacrylate absorbent (Stasorb, A. E. Staley Company) is applfed on the surface of the molten curtain. The curtain is allowed to cool to obtain a non-disintegrative absorbent product bearing absorbent on one major surface thereof. The product shows good absorptive properties.
Example XVII
The composition employed in Example I is extruded to form a monofilament of about 1 mil in diameter.
The monofilament on contact with water readily absorbs water to form a swollen rope.
The absorbent products of the present invention are useful in many articles where absorption of aqueous fluid is desired, such as diapers, bandages, pads, blankets, packaging materials, and the like. The products are especially adapted to be employed in the manufacture of certain articles.
The absorbent product in the configuration of a film may be employed as the absorbent layer in a novel thin diaper of less bulk than a fabric diaper but of high absorptive capability. For such use, the absorbent film product may be either one having the absorbent dispersed throughout the film or one having the absorbent dispersed on one surface of the film. When the film product has absorbent dispersed throughout the film, it is desirable that the product be faced with a liquid permeable facing sheet 21 and be backed with a liquid impermeable backing sheet 22 and joined by conventional means to form a diaper 20 seen in Figure 7. The facing sheet may be of a conventional fluid permeable cellulosic material.The backing sheet may be of conventional fluid impermeable material such as polyethylene, or of co-polyester orthermoplasticelastomeric film such as used in the absorbent product, the latter thermoplastic-elastic film also described in
U.S. patent 4,024,312. A diaper having a stretchable absorbent layer and elastic backing layer by use of thermoplastic-elastomeric block copolymer as both matrix and backing film permits the diaper to be thin and dfa surface area sufficient only to provide a snug fit around the wearer. The expansion of the absorbent product which occurs in use would be accompanied by a concurrent expansion of the backing layer, the expansion taking place only in amounts sufficient to accommodate the swollen absorbent product.
'When the film product is one that has absorbent dispersed on one side of the film, the film product may serve the function of both the absorbent layer and the backing layer, the side of the film not bearing the absorbent serving as a backing layer. The absorbent film in the latter embodiment generally would be of a heavier gauge which can be determined readily by the skilled in the art.
A film product having absorbent dispersed throughout the matrix may also be employed as a coating on a substrate. In such application, an extrudable composition or a film forming solvent casting composition previously described is extruded or cast onto a substrate film in a conventional manner. In addition to coated films, coated filament may be produced by extrusion coating wherein a filament or rope substrate bears the absorbent product as a coating as seen in Figure 6.
The absorbent product having absorbent dispersed throughout the matrix may be extruded through a die fitted with a cylindrical orifice to produce a rope or flexible rod. By the use of a cross-head die, a supporting element in the form of a string, monofilament or wire may be coated with a composition such as the one previously described to obtain a coated core substrate which may serve as the basis of a slender tampon 25 such as illustrated in Figure 8. Such tampon may be of a conventional length but have a diameter in the range of about 50 mils to about 400 mils. The advantage of a tampon made of the absorbent product of the present invention is the slender quality of the article to provide for ease in insertion while still having the same or greater absorptive capacity as a tampon of much larger dimensions.
Example XVIII
A composition consisting of a 30 percent solids dispersion in toluene of 100 parts by weight of Kraton 1107 and 100 parts by weight of starch acrylate absorbent (hydrolyzed starch acrylonitrile graft copolymer) is prepared by dispersing Kraton 1107 in toluene and thereafter rapidly stirring in starch acrylate absorbent.
The composition is cast onto silicone paper and the solvent evaporated to obtain a flexible, elastic absorbent film of about 10 mils in thickness which absorbs more than ten times its weight of water becoming a gelatinous rubbery film.
The film is incorporated between a water-permeable diaper facing and water-impermeable diaper backing to produce an absorbent diaper having a thickness approximately 20 to 25 mils compared to a thickness of about 140 milsfora conventional diaper.
Example XIX
The extrudable composition of Example I is extruded intermittently via a cross-head die onto a cotton string forming intermittently coated lengths, each coated length being about 1.7 x 103 mils in length and about 200 mils in diameter. On completion of the extrusion, the string is cut in the uncoated part to form slender tampons.
Example XX
The film product of Example Xis incorporated between a water permeable diaper facing and a water-impermeable diaper backing to produce an absorbent diaper having a thickness approximately 20 to 25 mils compared to a thickness of about 140 mils for a conventional diaper.
Example XXI
The extrudable composition of Example Xis extruded intermittently via a cross-head die onto a cotton string forming intermittently coated lengths, each coated length being about 1.7 x 1 103 and about 200 mils in diameter. On completion of the extrusion, the string is cut in the uncoated part to form slender tampons.
Claims (23)
1. Aflexible non-disintegrative absorbent product comprising a water-insoluble substantially nonswelling matrix of a polymer having thermoplastic properties and selected from (a) a thermoplasticelastomeric block copolymer and (b) a thermoplastic co-polyester polymer, said matrix bearing a uniformly dispersed particulate water-insoluble water-swellable organic polymer absorbent.
2. A product according to Claim 1 in which the absorbent has a particle size of from about 1 micron to about 2 x 104 microns in cross section and comprises from about 5 to about 200 parts per 100 parts by weight of matrix polymer.
3. A product according to Claim 1 in which the product is in the form of a film.
4. A product according to Claim 1 in which the product is in the form of a monofilament or rope.
5. A product according to Claim 1 in which the matrix polymer is a thermoplastic-elastomeric A-B-A or
A-B block copolymer or a mixture thereof in which A represents an alkenylarene polymer block and B represents a polymer block of a conjugated lower aliphatic diene or a lower aliphatic alkene, and in which the polymer absorbent is a synthetic acrylate polymer or a modified polysaccharide.
6. A product according to Claim 1 in which the matrix polymer is a thermoplastic co-polyester of at least two different ester units, each unit being a condensation product of a dicarboxylic acid and an aliphatic diol G and in which the polymer absorbent is a synthetic acrylate polymer or a modified polysaccharide.
7. A product according to Claim 1 in which the particulate polymer absorbent is at least partially imbedded in the matrix.
8. A non-aqueous process for preparing a flexible product having a water-insoluble substantially non-swelling matrix of a polymer having thermoplastic properties bearing a uniformly dispersed particulate water-insoluble water-swellable synthetic organic polymer absorbent which comprises
1) intimately mixing the matrix polymer and the polymer absorbent to a substantially homogeneous
blend, and
2) extruding the blend.
9. A process according to Claim 8 in which the polymer having thermoplastic properties is a thermoplastic-elastomeric A-B-A or A-B block copolymer or a mixture thereof in which A represents an alkenylarene polymer block and B represents a polymer block of a conjugated lower aliphatic diene or a lower aliphatic alkene, and in which the polymer absorbent is a synthetic acrylate polymer.
10. A process according to Claim 8 in which the polymer having thermoplastic properties is a co-polyester of at least two different ester units each being a condensation product of a dicarboxylic acid and an aliphatic diol, and in which the polymer absorbent is a synthetic acrylate polymer.
11. A process according to Claim 8 in which the product is a film.
12. A process according to Claim 8 in which the product is a monofilament.
13. A non-aqueous process for preparing absorbent film of elastic and thermoplastic properties and
having a water-insoluble substantiaLly non-swelling matrix of a thermoplastic-elastomeric polymer bearing a
uniformly dispersed particulate water-insoluble water-swellable organic polymer absorbent which com
prises
1) intimately mixing the thermoplastic-elastomeric polymer and the polymer absorbent in an organic
solvent composition, and
2) casting the composition.
14. A process according to Claim 13 in which the thermoplastic-elastomer polymer is an A-B-A or A-B
block copolymer or a mixture thereof in which A represents an alkenylarene polymer block and B represents
a polymer block of a conjugated lower aliphatic diene or a lower aliphatic alkene, and in which the polymer
absorbent is selected from the group consisting of synthetic acrylate polymer, cellulose acrylate polymer,
starch acrylate polymer and cross-linked carboxymethylcellulose.
15. An extrudable composition suitable for preparing an absorbent product having elastic and thermoplastic properties comprising
(a) a thermoplastic-elastomeric polymer comprising an A-B-A or A-B block copolymer or a mixture
thereof in which A represents an alkenylarene polymer block and B represents a polymer block of a
conjugated lower aliphatic diene or a lower aliphatic alkene, and
(b) a synthetic acrylate polymer.
16. An extrudable composition suitable for preparing a thermoplastic absorbent product comprising
(a) a co-polyester of at least two different ester units, each unit being a condensation product of a
dicarboxylic acid and an aliphatic diol; and
(b) a synthetic acrylate polymer.
17. Afilm composition suitable for preparing by casting an absorbentfilm having elastic and
thermoplastic properties comprising
(a) a thermoplastic-elastomeric polymer comprising and A-B-A or A-B block copolymer or a mixture
thereof in which A represents a polymer block of a conjugated lower aliphatic diene or a lower
aliphatic alkene,
(b) a polymer absorbent selected from the group consisting of synthetic acrylate polymer, cellulose
acrylate polymer, starch acrylate polymer and cross-linked carboxymethylcellulose, and
(c) an organic solvent.
18. Athin absorbent article comprising an absorbent product of Claim 5 or 6 faced with a liquid
permeable sheet.
19. An article according to Claim 18 in which the absorbent product is, in addition, backed with a liquid
impermeable sheet.
20. A tampon comprising an absorbent product of Claim 5 or 6.
21. A product according to Claim 1, substantially as described with reference to any Figure of the
accompanying drawing.
22. A process according to Claim 8 or 13, substantially as described in any of the foregoing Examples.
23. A product, or film, prepared by a process according to any of Claims 8 to 14, or Claim 22.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US8888279A | 1979-10-29 | 1979-10-29 | |
US06/088,881 US4318408A (en) | 1979-10-29 | 1979-10-29 | Absorbent products |
Publications (2)
Publication Number | Publication Date |
---|---|
GB2061974A true GB2061974A (en) | 1981-05-20 |
GB2061974B GB2061974B (en) | 1983-05-18 |
Family
ID=26779143
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8034643A Expired GB2061974B (en) | 1979-10-29 | 1980-10-28 | Absorbent products processes and compositions |
Country Status (12)
Country | Link |
---|---|
AU (1) | AU538142B2 (en) |
BR (1) | BR8006965A (en) |
CA (1) | CA1161819A (en) |
DE (1) | DE3040768A1 (en) |
ES (1) | ES8204454A1 (en) |
FR (1) | FR2468405B1 (en) |
GB (1) | GB2061974B (en) |
IT (1) | IT1133046B (en) |
NL (1) | NL8005908A (en) |
NZ (1) | NZ195264A (en) |
PH (2) | PH17545A (en) |
PT (1) | PT71979B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2095266A (en) * | 1981-03-20 | 1982-09-29 | Akzo Nv | Hydrophilic polyester composition |
US4675209A (en) * | 1982-02-02 | 1987-06-23 | Nordson Corporation | Process and device for the application of a high-active absorber on a substrate |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1319414A1 (en) * | 2001-12-11 | 2003-06-18 | The Procter & Gamble Company | Liquid absorbing thermoplastic materials and the utilization thereof in absorbent articles |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3888257A (en) * | 1973-10-01 | 1975-06-10 | Parke Davis & Co | Disposable absorbent articles |
US4124654A (en) * | 1974-06-07 | 1978-11-07 | General Electric Company | Thermoplastic molding compositions of vinyl aromatic compound alpha, beta unsaturated cyclic anhydride copolymers |
US4026849A (en) * | 1975-10-03 | 1977-05-31 | The United States Of America As Represented By The Secretary Of Agriculture | Composite compositions from graft polymerized rigid fillers |
GB1550614A (en) * | 1976-06-28 | 1979-08-15 | Unilever Ltd | Absorbent materials |
DE2736205A1 (en) * | 1977-08-11 | 1979-02-22 | Hoechst Ag | WATER VAPOR ABSORBENT AND WATER VAPOR PERMEABLE AREA MADE OF RUBBER AND A PROCESS FOR ITS MANUFACTURING |
US4156664A (en) * | 1978-01-31 | 1979-05-29 | Henkel Corporation | Film forming SGP |
SE7802305L (en) * | 1978-03-01 | 1979-09-02 | Landstingens Inkopscentral | P Y * LARSSON # OKERUM |
JPS54125896A (en) * | 1978-03-23 | 1979-09-29 | Kuraray Co | Absorbing body that have excellent water absorbing capacity |
JPS5558700U (en) * | 1978-10-12 | 1980-04-21 |
-
1980
- 1980-10-03 AU AU62930/80A patent/AU538142B2/en not_active Expired
- 1980-10-15 NZ NZ195264A patent/NZ195264A/en unknown
- 1980-10-27 IT IT50012/80A patent/IT1133046B/en active
- 1980-10-27 CA CA000363322A patent/CA1161819A/en not_active Expired
- 1980-10-27 PT PT71979A patent/PT71979B/en unknown
- 1980-10-27 FR FR808022925A patent/FR2468405B1/en not_active Expired - Lifetime
- 1980-10-28 GB GB8034643A patent/GB2061974B/en not_active Expired
- 1980-10-28 ES ES496355A patent/ES8204454A1/en not_active Expired
- 1980-10-28 NL NL8005908A patent/NL8005908A/en not_active Application Discontinuation
- 1980-10-28 PH PH24779A patent/PH17545A/en unknown
- 1980-10-29 DE DE19803040768 patent/DE3040768A1/en active Granted
- 1980-10-29 BR BR8006965A patent/BR8006965A/en not_active IP Right Cessation
-
1983
- 1983-10-21 PH PH29755A patent/PH19611A/en unknown
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2095266A (en) * | 1981-03-20 | 1982-09-29 | Akzo Nv | Hydrophilic polyester composition |
US4675209A (en) * | 1982-02-02 | 1987-06-23 | Nordson Corporation | Process and device for the application of a high-active absorber on a substrate |
Also Published As
Publication number | Publication date |
---|---|
CA1161819A (en) | 1984-02-07 |
AU6293080A (en) | 1981-05-07 |
NL8005908A (en) | 1981-06-01 |
GB2061974B (en) | 1983-05-18 |
PT71979B (en) | 1982-04-02 |
ES496355A0 (en) | 1982-05-01 |
NZ195264A (en) | 1982-12-07 |
DE3040768C2 (en) | 1993-02-04 |
FR2468405B1 (en) | 1992-09-18 |
PH17545A (en) | 1984-09-19 |
PH19611A (en) | 1986-05-27 |
PT71979A (en) | 1980-11-01 |
IT1133046B (en) | 1986-07-09 |
BR8006965A (en) | 1981-05-05 |
ES8204454A1 (en) | 1982-05-01 |
DE3040768A1 (en) | 1981-09-24 |
AU538142B2 (en) | 1984-08-02 |
FR2468405A1 (en) | 1981-05-08 |
IT8050012A0 (en) | 1980-10-27 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
PCNP | Patent ceased through non-payment of renewal fee |