JPH04211104A - Magnetic fluid composition and production thereof - Google Patents
Magnetic fluid composition and production thereofInfo
- Publication number
- JPH04211104A JPH04211104A JP3023262A JP2326291A JPH04211104A JP H04211104 A JPH04211104 A JP H04211104A JP 3023262 A JP3023262 A JP 3023262A JP 2326291 A JP2326291 A JP 2326291A JP H04211104 A JPH04211104 A JP H04211104A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic fluid
- organic solvent
- low
- fluid composition
- fine particles
- 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
- 239000011553 magnetic fluid Substances 0.000 title claims abstract description 103
- 239000000203 mixture Substances 0.000 title claims abstract description 80
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- 239000002270 dispersing agent Substances 0.000 claims abstract description 62
- 239000010419 fine particle Substances 0.000 claims abstract description 61
- 239000000654 additive Substances 0.000 claims abstract description 60
- 230000005294 ferromagnetic effect Effects 0.000 claims abstract description 59
- 239000003960 organic solvent Substances 0.000 claims abstract description 54
- 230000000996 additive effect Effects 0.000 claims abstract description 48
- 238000000034 method Methods 0.000 claims abstract description 22
- 229920000642 polymer Polymers 0.000 claims abstract description 19
- 239000002612 dispersion medium Substances 0.000 claims abstract description 10
- 238000009835 boiling Methods 0.000 claims description 48
- 239000002609 medium Substances 0.000 claims description 29
- 239000002245 particle Substances 0.000 claims description 26
- 239000003495 polar organic solvent Substances 0.000 claims description 20
- -1 polyethylene Polymers 0.000 claims description 19
- 229920001083 polybutene Polymers 0.000 claims description 18
- 238000005406 washing Methods 0.000 claims description 11
- 150000002430 hydrocarbons Chemical class 0.000 claims description 8
- 239000002904 solvent Substances 0.000 claims description 8
- 125000004432 carbon atom Chemical group C* 0.000 claims description 6
- 239000000178 monomer Substances 0.000 claims description 5
- 229920001577 copolymer Polymers 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 229930195733 hydrocarbon Natural products 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 229920000625 Poly(1-decene) Polymers 0.000 claims description 3
- 239000005062 Polybutadiene Substances 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 3
- 239000004743 Polypropylene Substances 0.000 claims description 3
- 239000004793 Polystyrene Substances 0.000 claims description 3
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 3
- 229920002857 polybutadiene Polymers 0.000 claims description 3
- 229920000573 polyethylene Polymers 0.000 claims description 3
- 229920001155 polypropylene Polymers 0.000 claims description 3
- 229920002223 polystyrene Polymers 0.000 claims description 3
- 125000001174 sulfone group Chemical group 0.000 claims description 3
- 239000011248 coating agent Substances 0.000 claims description 2
- 238000000576 coating method Methods 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims description 2
- 125000001183 hydrocarbyl group Chemical group 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 45
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 39
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 24
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 description 19
- 239000006249 magnetic particle Substances 0.000 description 14
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- 239000007788 liquid Substances 0.000 description 9
- 238000007711 solidification Methods 0.000 description 9
- 230000008023 solidification Effects 0.000 description 9
- 239000001384 succinic acid Substances 0.000 description 9
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 8
- 239000002253 acid Substances 0.000 description 8
- 239000007822 coupling agent Substances 0.000 description 8
- 239000004094 surface-active agent Substances 0.000 description 8
- 230000008569 process Effects 0.000 description 7
- 150000003839 salts Chemical class 0.000 description 7
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 6
- 239000011554 ferrofluid Substances 0.000 description 6
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 5
- 239000006087 Silane Coupling Agent Substances 0.000 description 5
- USIUVYZYUHIAEV-UHFFFAOYSA-N diphenyl ether Natural products C=1C=CC=CC=1OC1=CC=CC=C1 USIUVYZYUHIAEV-UHFFFAOYSA-N 0.000 description 5
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 4
- 238000005054 agglomeration Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 239000000084 colloidal system Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 239000012530 fluid Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 229920013639 polyalphaolefin Polymers 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 4
- 239000006228 supernatant Substances 0.000 description 4
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 4
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- VQTUBCCKSQIDNK-UHFFFAOYSA-N Isobutene Chemical compound CC(C)=C VQTUBCCKSQIDNK-UHFFFAOYSA-N 0.000 description 3
- 229920002367 Polyisobutene Polymers 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- IAQRGUVFOMOMEM-UHFFFAOYSA-N butene Natural products CC=CC IAQRGUVFOMOMEM-UHFFFAOYSA-N 0.000 description 3
- 238000005119 centrifugation Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000499 gel Substances 0.000 description 3
- 239000000693 micelle Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- ZHGIKBCGOGBDFG-UHFFFAOYSA-N 1-icosylnaphthalene Chemical compound C1=CC=C2C(CCCCCCCCCCCCCCCCCCCC)=CC=CC2=C1 ZHGIKBCGOGBDFG-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 2
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 description 2
- 150000001336 alkenes Chemical class 0.000 description 2
- 125000003545 alkoxy group Chemical group 0.000 description 2
- 125000000129 anionic group Chemical group 0.000 description 2
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 2
- 125000002091 cationic group Chemical group 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- ZQPPMHVWECSIRJ-MDZDMXLPSA-N elaidic acid Chemical compound CCCCCCCC\C=C\CCCCCCCC(O)=O ZQPPMHVWECSIRJ-MDZDMXLPSA-N 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 150000002170 ethers Chemical class 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 description 2
- 239000002480 mineral oil Substances 0.000 description 2
- 235000010446 mineral oil Nutrition 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- KDYFGRWQOYBRFD-UHFFFAOYSA-L succinate(2-) Chemical compound [O-]C(=O)CCC([O-])=O KDYFGRWQOYBRFD-UHFFFAOYSA-L 0.000 description 2
- 239000013638 trimer Substances 0.000 description 2
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 description 1
- ZNQVEEAIQZEUHB-UHFFFAOYSA-N 2-ethoxyethanol Chemical compound CCOCCO ZNQVEEAIQZEUHB-UHFFFAOYSA-N 0.000 description 1
- SVONRAPFKPVNKG-UHFFFAOYSA-N 2-ethoxyethyl acetate Chemical compound CCOCCOC(C)=O SVONRAPFKPVNKG-UHFFFAOYSA-N 0.000 description 1
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 description 1
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 description 1
- DPUOLQHDNGRHBS-UHFFFAOYSA-N Brassidinsaeure Natural products CCCCCCCCC=CCCCCCCCCCCCC(O)=O DPUOLQHDNGRHBS-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- URXZXNYJPAJJOQ-UHFFFAOYSA-N Erucic acid Natural products CCCCCCC=CCCCCCCCCCCCC(O)=O URXZXNYJPAJJOQ-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 239000005642 Oleic acid Substances 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical group OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 239000002280 amphoteric surfactant Substances 0.000 description 1
- 239000003945 anionic surfactant Substances 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 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
- 150000007942 carboxylates Chemical group 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- XNMQEEKYCVKGBD-UHFFFAOYSA-N dimethylacetylene Natural products CC#CC XNMQEEKYCVKGBD-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 125000003700 epoxy group Chemical group 0.000 description 1
- DPUOLQHDNGRHBS-KTKRTIGZSA-N erucic acid Chemical compound CCCCCCCC\C=C/CCCCCCCCCCCC(O)=O DPUOLQHDNGRHBS-KTKRTIGZSA-N 0.000 description 1
- FWDBOZPQNFPOLF-UHFFFAOYSA-N ethenyl(triethoxy)silane Chemical compound CCO[Si](OCC)(OCC)C=C FWDBOZPQNFPOLF-UHFFFAOYSA-N 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 239000011790 ferrous sulphate Substances 0.000 description 1
- 235000003891 ferrous sulphate Nutrition 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 229920001580 isotactic polymer Polymers 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 230000005291 magnetic effect Effects 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 125000000956 methoxy group Chemical group [H]C([H])([H])O* 0.000 description 1
- 239000011859 microparticle Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000002736 nonionic surfactant Substances 0.000 description 1
- SLYCYWCVSGPDFR-UHFFFAOYSA-N octadecyltrimethoxysilane Chemical compound CCCCCCCCCCCCCCCCCC[Si](OC)(OC)OC SLYCYWCVSGPDFR-UHFFFAOYSA-N 0.000 description 1
- AJCDFVKYMIUXCR-UHFFFAOYSA-N oxobarium;oxo(oxoferriooxy)iron Chemical compound [Ba]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O AJCDFVKYMIUXCR-UHFFFAOYSA-N 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical group 0.000 description 1
- 229920000738 poly(p-divinylbenzene) polymer Polymers 0.000 description 1
- 229920001748 polybutylene Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000000565 sealant Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 125000005372 silanol group Chemical group 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- 150000003871 sulfonates Chemical group 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 125000003396 thiol group Chemical group [H]S* 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 238000001238 wet grinding Methods 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/44—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids
- H01F1/445—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids the magnetic component being a compound, e.g. Fe3O4
Abstract
Description
［０００１１ [00011
【産業上の利用分野］この発明は、真空装置、コンピュ
ータハードディスク駆動装置等の軸シールに好適に利用
できる、耐熱性、耐水性に優れ、そして低粘度な磁性流
体組成物及びその製造方法に関するものである。
［０００２］
【従来の技術】従来から明らかなように、磁性流体組成
物は、強磁性体微粒子、キャリア（分散媒）、及び分散
剤とから本質的に構成され、磁性粒子に分散剤が吸着（
結合）することにより、キャリア中に磁性粒子を均一に
分散させているものである。
［０００３］ ところで、このような磁性流体を高温、
高湿の条件下におくと、分散剤が磁性粒子から脱着した
り、さらに、キャリア内に侵入した水分子が磁性粒子表
面に吸着して分散剤と置換したりすることにより、磁性
粒子から分散剤が不可逆的に脱着する。このような状態
が生ずると磁性粒子同士の凝着が進行して、磁性流体が
ゲル化して、粘度が高くなるなど初期の性質が失われる
ことになる。特に、低トルク特性が要求されるシール用
磁性流体では大きな問題となる。
［０００４］そこで、従来から磁性流体の耐熱性及び耐
水性を向上するために、磁性流体に種々の改良を施した
従来例が存在する。このような従来例として、ポリブテ
ンコハク酸を分散剤として用いた磁性流体組成物が存在
する（米国特許第３７００５９号）。
［０００５］[Industrial Application Field] This invention relates to a magnetic fluid composition with excellent heat resistance, water resistance, and low viscosity, which can be suitably used for shaft seals of vacuum devices, computer hard disk drives, etc., and a method for producing the same. It is. [0002] As is known from the past, a magnetic fluid composition essentially consists of ferromagnetic fine particles, a carrier (dispersion medium), and a dispersant, and the dispersant is adsorbed to the magnetic particles. (
The magnetic particles are uniformly dispersed in the carrier by bonding (bonding). [0003] By the way, when such a magnetic fluid is heated to a high temperature,
When placed under high humidity conditions, the dispersant desorbs from the magnetic particles, and water molecules that have entered the carrier are adsorbed to the surface of the magnetic particles and replace the dispersant, causing them to be dispersed from the magnetic particles. The agent is irreversibly desorbed. When such a state occurs, the adhesion of magnetic particles progresses, and the magnetic fluid gels, resulting in loss of initial properties such as increased viscosity. This is particularly a big problem in magnetic fluids for seals that require low torque characteristics. [0004] Therefore, there have been conventional examples in which various improvements have been made to magnetic fluids in order to improve the heat resistance and water resistance of magnetic fluids. As such a conventional example, there is a magnetic fluid composition using polybutenesuccinic acid as a dispersant (US Pat. No. 370,059). [0005]
【発明が解決しようとする課題】しかしながら、この従
来例において、磁性流体組成物の耐熱性、耐水性を向上
するために使用される分散剤は、分子量が大きいオリゴ
マ又はポリマであるため、磁性粒子を分散させるのに必
要な景だけ分散剤を使用すると、磁性流体の粘度が高く
なるのを避けることができない。この結果、分子量が大
きいオリゴマ又はポリマである分散剤を低トルクである
ことが要求されるシール用磁性流体に使用することは不
適当であった。
［０００６］即ち、従来の磁性流体では、耐熱性、耐水
性を向上しようとすると粘度が高くなり、逆に、粘度を
低くしようとすると耐熱性、耐水性が低下するという課
題があった。
［０００７］そこで、この発明は、このような課題を解
決するために、耐熱性、耐水性に優れ、且つ、低粘度で
もある磁性流体組成物及びその製造方法を提供すること
を目的とする。
［０００８］[Problems to be Solved by the Invention] However, in this conventional example, the dispersant used to improve the heat resistance and water resistance of the magnetic fluid composition is an oligomer or polymer with a large molecular weight. If only enough dispersant is used to disperse the magnetic fluid, it is impossible to avoid increasing the viscosity of the magnetic fluid. As a result, it has been inappropriate to use dispersants that are oligomers or polymers with large molecular weights in sealing magnetic fluids that require low torque. [0006] That is, in conventional magnetic fluids, when trying to improve heat resistance and water resistance, the viscosity increases, and conversely, when trying to lower the viscosity, the heat resistance and water resistance decrease. [0007] Therefore, in order to solve such problems, it is an object of the present invention to provide a magnetic fluid composition that has excellent heat resistance, water resistance, and low viscosity, and a method for producing the same. [0008]
【課題を解決するための手段】この目的を達成すること
により前記課題を解決できる本発明は、低揮発性有機溶
媒からなる分散媒と、該有機溶媒と親和性のある親油基
及び極性基を有する低分子量の分散剤と、該分散剤で表
面が被覆され前記有機溶媒中に分散された強磁性体微粒
子と、高分子鎖の親油基及び極性基を有し、前記分散媒
中に加えられる添加剤と、から本質的になることを特徴
とする磁性流体組成物に係るものである。
［０００９］ この添加剤の高分子鎖は、炭素数が２５
〜１５００の炭化水素からなることが好ましい。そして
、このような添加剤の炭化水素鎖として、ポリエチレン
。
ポリプロピレン、ポリブテン、ポリブタジェン、ポリ（
１−デセン）、ポリスチレンの少なくとも一つ及びそれ
ぞれのモノマによるコポリマを挙げることができる。
さらに、添加剤の極性基として、カルボキシル基及び／
又はスルホン基を挙げることができる。
［００１０１前記添加剤の分子量は、５００〜２０００
０であることが望ましい。また、添加剤の含有量は０゜
５〜３０重量％であることが望ましい。そして、本発明
はまた、強磁性体微粒子に対して、低沸点無極性有機溶
媒と、これと親和性のある親油基を有する分散剤とを加
えて、該分散剤で強磁性体微粒子の表面に結合させ、そ
の後前記低沸点無極性有機溶媒を除去して前記分散剤で
表面が被覆された強磁性体微粒子を得る工程と、この強
磁性体微粒子を低沸点極性有機溶媒を用いて洗浄する工
程と、該洗浄後の強磁性体微粒子に低揮発性有機溶媒と
高分子鎖の親油基及び極性基を有する添加剤とを加えて
混合する工程と、を有することを特徴とする磁性流体組
成物の製造方法、ないしは、強磁性体微粒子に対して、
低沸点無極性有機溶媒と、これと親和性のある親油基を
有して強磁性体微粒子の表面を被覆する分散剤とを加え
ることにより、該分散剤で表面を被覆された強磁性体微
粒子が前記低沸点無極性有機溶媒中に均一に分散された
中間媒体を得る工程と、該中間媒体を低沸点極性有機溶
媒で洗浄する工程と、該洗浄前又は洗浄後の中間媒体中
の分散性の悪い前記強磁性体微粒子を分離する工程と、
当該分離後中間媒体に低揮発性有機溶媒を加えて混合物
とする工程と、該混合物を加熱して前記低沸点有機溶媒
を蒸発分離せしめて磁性流体を得る工程と、該磁性流体
に高分子鎖の親油基及び極性基を有する添加剤を加える
工程と、を有することを特徴とする磁性流体組成物の製
造方法に関するものである。
［００１１］前記添加剤の添加は前記低揮発性有機溶媒
を加えて混合物とする工程で行う、ことも可能である。
［００１２］[Means for Solving the Problems] The present invention, which can solve the above problems by achieving this object, provides a dispersion medium made of a low-volatile organic solvent, and a lipophilic group and a polar group having an affinity for the organic solvent. ferromagnetic fine particles whose surfaces are coated with the dispersant and are dispersed in the organic solvent; and ferromagnetic fine particles having a lipophilic group and a polar group in the polymer chain, and which have a lipophilic group and a polar group in the dispersion medium. 1. A magnetic fluid composition consisting essentially of: an additive; [0009] The polymer chain of this additive has 25 carbon atoms.
Preferably it consists of ~1500 hydrocarbons. And polyethylene, as a hydrocarbon chain of such additives. Polypropylene, polybutene, polybutadiene, poly(
1-decene), polystyrene and copolymers of the respective monomers. Furthermore, as polar groups of the additive, carboxyl groups and/or
Alternatively, a sulfone group can be mentioned. [00101 The molecular weight of the additive is 500 to 2000
It is desirable that it be 0. Further, the content of the additive is preferably 0.5 to 30% by weight. The present invention also provides a method of adding a low-boiling point nonpolar organic solvent and a dispersant having a lipophilic group with affinity to the ferromagnetic fine particles, and using the dispersant to form the ferromagnetic fine particles. bonding to the surface and then removing the low-boiling nonpolar organic solvent to obtain ferromagnetic fine particles whose surfaces are coated with the dispersant, and washing the ferromagnetic fine particles using the low-boiling polar organic solvent. and a step of adding and mixing a low-volatile organic solvent and an additive having a lipophilic group and a polar group in a polymer chain to the washed ferromagnetic fine particles. Method for producing fluid composition or ferromagnetic fine particles,
A ferromagnetic material whose surface is coated with the dispersant is obtained by adding a low-boiling nonpolar organic solvent and a dispersant that has a lipophilic group that has affinity with the solvent and coats the surface of the ferromagnetic fine particles. A step of obtaining an intermediate medium in which fine particles are uniformly dispersed in the low boiling point non-polar organic solvent, a step of washing the intermediate medium with a low boiling point polar organic solvent, and dispersion in the intermediate medium before or after the washing. a step of separating the ferromagnetic fine particles having poor properties;
A step of adding a low-volatile organic solvent to the intermediate medium after the separation to form a mixture, a step of heating the mixture to evaporate and separate the low-boiling point organic solvent to obtain a magnetic fluid, and adding a polymer chain to the magnetic fluid. Adding an additive having a lipophilic group and a polar group. [0011] It is also possible to add the additive in a step of adding the low-volatile organic solvent to form a mixture. [0012]
【作用】本発明者が鋭意検討したところ、高分子鎖から
なる親油基及び極性基を有する界面活性剤を磁性流体に
分散剤としてではなく、キャリア中に添加される添加剤
として加えると、磁性流体組成物の耐熱性、耐水性を向
上でき、且つ、粘度の増大がなく低粘度を維持できる磁
性流体組成物を得ることができる、という知見を得た。
［００１３］磁性流体組成物の粘度の増大を防ぐために
は、分散剤に低分子量のものが使用されるが、このよう
な磁性流体組成物は高温、高湿の環境下で分散剤が磁性
粒子から脱着する。この場合、分散剤はキャリア中に侵
入した水分に吸着するか分散剤同士が吸着してミセル等
を形成して、分散剤が強磁性体微粒子の会合部分に再度
吸着することが困難となる。このような分散剤の脱着が
発生すると、前記のよう磁性粒子同士の凝集が発生する
。
［００１４］ このような状態において、本発明のよう
な添加剤が磁性流体に添加されていると、添加剤が磁性
粒子の分散剤脱着部分に優先して吸着することにより、
磁性粒子同士の凝集を防止する。本発明に係る添加剤は
、高分子鎖からなる親油基を有するために水との親和性
が相対的に低くなり、この結果、水とのミセルを発生す
ることもなく磁性粒子に優先して吸着することができる
。
従って、磁性流体の耐熱性、耐水性が向上する。
［００１５］高分子の界面活性剤を分散剤として使用す
ると、磁性粒子の分散性を充分確保する観点から、その
含有量は通常３０重量％以上必要となる。しかし、これ
だけ高分子の分散剤を添加すると、耐熱性、耐水性は向
上するが粘度の増大を避けることができない。
［００１６］Ｌかしながら、本発明のように分散剤とし
ては低分子量の界面活性剤を使用し、高分子の親油基を
有する界面活性剤を添加剤として用いると、その添加量
を少なく抑えることが可能となる。従って、磁性流体の
粘度の増大を防止し、低粘度を維持することができる。
しかも、係る添加剤を加えることにより、前記のように
この添加剤は磁性流体の分散剤脱着部分に優先して吸着
することから、分散剤を低分子量化することができるた
め、この点からしても磁性流体の粘度の増大を防止する
ことが可能となる。
［００１７］また、この添加剤自体は疎水性が強いため
、キャリア中に添加されてもキャリア自体の吸水性が高
くなることもない。つまり親水性が低くキャリア中での
ミセル形成能も低いため、強磁性流体微粒子に未吸着な
状態でも水を取り込み難い。この結果、この点からも磁
性流体組成物の耐水性を阻害しない。
［００１８１本発明に係る添加剤の親油基は高分子鎖か
らなり、係る高分子鎖の例として脂肪族炭化水素系のも
の、芳香族炭化水素系のものが挙げられる。脂肪族炭化
水素系のものとして、例えば、ポリエチレン、ポリプロ
ピレン、ポリブテン、ポリブタジェン、ポリ（１−デセ
ン）の少なくとも一つ及びそれぞれのモノマによるコポ
リマ（コオリゴマ）等が挙げられる。ここで、ポリブテ
ンには、イソブチン（＝イソブチレン）とノルマルブテ
ン（１−ブテン、２−ブテン）混合物の重合体である狭
義のポリブテン、イソブチンのホモポリマであるポリイ
ソブチン、それにブテン−１のアイソタクチックポリマ
であるポリブテン１がある。
［００１９］芳香族炭化水素系のものとしては、例えば
、ポリスチレン、ポリ（ｐ−ジビニルベンゼン）及びそ
れぞれのモノマとエチレンなどの脂肪続炭化水素系のモ
ノマとコポリマ（オリゴマ）等が挙げられる。
［００２０１添加剤の高分子鎖の炭素数としては、２５
〜１５００であることが好ましい。ここで、炭素数が２
５未満であると添加剤の疎水性が充分でないため、磁性
粒子の分散剤脱着部分に優先して吸着することができず
組成物の耐熱性、耐水性の向上が充分でない。一方、炭
素数が１５００を越えると、たとえ添加剤として加えて
も粘度の増大を避けることができないおそれがある。よ
って、炭化水素鎖の炭素数を２５〜１５００にすること
が望ましい。
［００２１１添加剤の含有量は磁性流体組成物に対して
０．５〜３０重量％であることが好ましい。０．５重量
％未満であると、磁性流体組成物の耐熱性、耐水性の向
上が充分でないおそれがある。また、３０重量％を越え
ると、磁性流体の粘度が増大して低トルク性を発揮でき
ないおそれがある。
［００２２］そして、添加剤の分子量は５００〜２００
００であることが好ましい。分子量が５００未満である
と、添加物の疎水性が充分でないため磁性流体の耐熱性
、耐水性が低下するおそれがある。また、２００００を
越えると粘度が増大するおそれがある。
［００２３］また、添加剤の親水基としては、カルボン
酸塩、硫酸エステル塩、リン酸塩、スルホン酸塩、ホス
ホン酸塩、アミン塩等の従来から存在するカチオン型。
アニオン型の極性基を広く使用することが可能である。
そして、極性基が高分子鎖に複数結合しているものでも
良い。
［００２４］かかる添加剤の好適な具体例として、ポリ
ブテンコハク酸塩、ポリイソブチレンコハク酸塩、ポリ
ブテンスルホン酸塩、ポリα−オレフィンスルホン酸塩
ＣＲＣＨ＝ＣＨ（ＣＨ２） ＳＯ３ＮａＲ；ＣＨ２
１〕が挙げられる。このような添加剤の使用により低粘
度（５０〜１５０ｃｐ、４０℃）の磁性流体組成物を得
ることができる。
［００２５〕本発明の強磁性体微粒子の分散媒となる低
揮発性有機溶媒として（キャリア）としては、蒸気圧が
１×１０−１０〜１×１Ｏ−３Ｔｏｒｒ（２０℃）にあ
る鉱油をはじめとする種々の炭化水素５合成油類及びエ
ーテル類又はエステル類或いはシリコン油等の低揮発性
の有機溶媒が、磁性流体の用途に応じて適宜用いられる
。例えば、磁気ディスク用シーリング剤としての用途で
あれば、ポリアルファ（α）オレフィン油とか、アルキ
ルナフタレン油、ヘキサデシルジフェニルエーテル、ヘ
キサデシルジフェニルエーテルとオクタデシルジフェニ
ルエーテルとの混合物、エイコシルナフタレン、トリー
２エチルへキシルトリメリテート等が好適である。
［００２６１本発明の強磁性流体粒子としては、周知の
湿式法により得られるマグネタイトコロイドを用い得る
。また、水もしくは有機溶媒中でマグネタイト粉末をボ
ールミルで粉砕するいわゆる湿式粉砕法で得られるもの
でも良い。
［００２７〕湿式粉砕法を利用する場合、研削液として
水以外に例えば、ヘキサン等の有機溶媒を用いるときに
は、強磁性体粉末とのその粒子表面に単分子層を形成で
きる量の後述する分散媒を加えたうえでボールミル中で
数時間以上粉砕しても良い。
［００２８］また、マグネタイト以外のマンガンフェラ
イト、コバルトフェライト、もしくはこれらと亜鉛、ニ
ッケルとの複合フェライトやバリウムフェライト等の強
磁性酸化物、又は鉄、コバルト、希土類などの強磁性金
属を用いることもできる。
［００２９］更にまた、強磁性体微粒子として前記湿式
法或いは湿式粉砕法によるもののほか、乾式法で得たも
のを用いることもできる。本発明の強磁性体微粒子の含
有量は、従来一般的に用いられている体積比で１〜２０
％の範囲は勿論のこと、必要に応じて７０％程度の極め
て高濃度のものであっても良い。すなわち、本発明によ
れば、後述するように強磁性体微粒子が低沸点有機溶媒
中に分散された中間媒体を利用することで、強磁性体微
粒子濃度を７０％にも達する高濃度に調整することがで
きる。これにより、磁化量の極めて高い磁性流体が得ら
れるものである。[Function] The present inventor has made extensive studies and found that if a surfactant having a lipophilic group and a polar group consisting of a polymer chain is added to the magnetic fluid not as a dispersant but as an additive added to the carrier. It has been found that it is possible to obtain a magnetic fluid composition that can improve the heat resistance and water resistance of the magnetic fluid composition, and can maintain a low viscosity without increasing viscosity. [0013] In order to prevent the viscosity of the magnetic fluid composition from increasing, a dispersant having a low molecular weight is used. Remove from. In this case, the dispersant adsorbs the moisture that has entered the carrier or the dispersants adsorb to each other to form micelles, making it difficult for the dispersant to adsorb again to the association portion of the ferromagnetic fine particles. When such desorption of the dispersant occurs, agglomeration of magnetic particles occurs as described above. [0014] In such a state, when the additive of the present invention is added to the magnetic fluid, the additive is preferentially adsorbed to the dispersant-desorbing portion of the magnetic particles, so that
Prevents agglomeration of magnetic particles. Since the additive according to the present invention has a lipophilic group consisting of a polymer chain, its affinity with water is relatively low, and as a result, it does not generate micelles with water and has priority over magnetic particles. can be adsorbed. Therefore, the heat resistance and water resistance of the magnetic fluid are improved. [0015] When a polymeric surfactant is used as a dispersant, its content usually needs to be 30% by weight or more from the viewpoint of ensuring sufficient dispersibility of the magnetic particles. However, when such a large amount of polymeric dispersant is added, although heat resistance and water resistance are improved, an increase in viscosity cannot be avoided. [0016] However, if a low molecular weight surfactant is used as a dispersant as in the present invention and a surfactant having a polymeric lipophilic group is used as an additive, the amount added can be reduced. It is possible to suppress it. Therefore, it is possible to prevent an increase in the viscosity of the magnetic fluid and maintain a low viscosity. Moreover, by adding such an additive, as mentioned above, this additive preferentially adsorbs to the dispersant-desorbing portion of the magnetic fluid, so it is possible to reduce the molecular weight of the dispersant. However, it is possible to prevent the viscosity of the magnetic fluid from increasing. [0017] Furthermore, since this additive itself has strong hydrophobicity, even if it is added to the carrier, the water absorbency of the carrier itself will not increase. In other words, it has low hydrophilicity and low ability to form micelles in the carrier, so it is difficult to take in water even when it is not adsorbed to the ferromagnetic fluid particles. As a result, from this point of view as well, the water resistance of the magnetic fluid composition is not impaired. [00181] The lipophilic group of the additive according to the present invention consists of a polymer chain, and examples of such polymer chains include aliphatic hydrocarbon-based ones and aromatic hydrocarbon-based ones. Examples of aliphatic hydrocarbons include at least one of polyethylene, polypropylene, polybutene, polybutadiene, and poly(1-decene), and copolymers (cooligomers) of each monomer. Here, polybutene includes polybutene in the narrow sense, which is a polymer of a mixture of isobutene (=isobutylene) and normal butene (1-butene, 2-butene), polyisobutene, which is a homopolymer of isobutyne, and isotactic polymer of butene-1. There is polybutene 1 which is [0019] Examples of aromatic hydrocarbons include polystyrene, poly(p-divinylbenzene), and copolymers (oligomers) of their respective monomers and aliphatic hydrocarbon monomers such as ethylene. [00201 The number of carbon atoms in the polymer chain of the additive is 25
It is preferable that it is 1500-1500. Here, the number of carbon atoms is 2
If it is less than 5, the hydrophobicity of the additive is insufficient, so that it cannot be adsorbed preferentially to the dispersant-desorbing portion of the magnetic particles, and the heat resistance and water resistance of the composition cannot be sufficiently improved. On the other hand, if the number of carbon atoms exceeds 1,500, there is a possibility that an increase in viscosity cannot be avoided even if it is added as an additive. Therefore, it is desirable that the number of carbon atoms in the hydrocarbon chain is 25 to 1,500. [00211 The content of the additive is preferably 0.5 to 30% by weight based on the magnetic fluid composition. If it is less than 0.5% by weight, the heat resistance and water resistance of the magnetic fluid composition may not be sufficiently improved. Moreover, if it exceeds 30% by weight, the viscosity of the magnetic fluid increases and there is a possibility that low torque performance cannot be achieved. [0022] And the molecular weight of the additive is 500 to 200
Preferably it is 00. When the molecular weight is less than 500, the hydrophobicity of the additive is insufficient, so that the heat resistance and water resistance of the magnetic fluid may be reduced. Moreover, if it exceeds 20,000, the viscosity may increase. [0023] Further, as the hydrophilic group of the additive, conventionally existing cationic groups such as carboxylates, sulfate ester salts, phosphates, sulfonates, phosphonates, and amine salts are used. It is possible to widely use polar groups of the anionic type. Further, it may be one in which a plurality of polar groups are bonded to a polymer chain. [0024] Preferred specific examples of such additives include polybutene succinate, polyisobutylene succinate, polybutene sulfonate, poly alpha-olefin sulfonate CRCH=CH(CH2) SO3NaR;CH2
1]. The use of such additives makes it possible to obtain magnetic fluid compositions with low viscosities (50-150 cp, 40°C). [0025] Examples of the low-volatility organic solvent (carrier) serving as a dispersion medium for the ferromagnetic fine particles of the present invention include mineral oil having a vapor pressure of 1 x 10-10 to 1 x 1 O-3 Torr (20°C). Various hydrocarbon 5 synthetic oils and ethers or esters, or low-volatility organic solvents such as silicone oil are used as appropriate depending on the use of the magnetic fluid. For example, for use as a sealant for magnetic disks, polyalpha (α) olefin oil, alkylnaphthalene oil, hexadecyl diphenyl ether, a mixture of hexadecyl diphenyl ether and octadecyl diphenyl ether, eicosylnaphthalene, tri-2-ethylhexyl Trimelitate and the like are preferred. [00261 As the ferrofluid particles of the present invention, magnetite colloids obtained by a well-known wet method may be used. Alternatively, it may be obtained by a so-called wet pulverization method in which magnetite powder is pulverized with a ball mill in water or an organic solvent. [0027] When using the wet grinding method, when using an organic solvent such as hexane in addition to water as the grinding fluid, an amount of the dispersion medium described below that can form a monomolecular layer on the particle surface of the ferromagnetic powder is added. may be added and then ground in a ball mill for several hours or more. [0028] In addition, ferromagnetic oxides other than magnetite such as manganese ferrite, cobalt ferrite, composite ferrite of these with zinc and nickel, barium ferrite, or ferromagnetic metals such as iron, cobalt, and rare earths can also be used. . [0029]Furthermore, in addition to the ferromagnetic fine particles obtained by the above-mentioned wet method or wet pulverization method, those obtained by a dry method can also be used. The content of the ferromagnetic fine particles of the present invention is 1 to 20% by volume, which is conventionally generally used.
Of course, the concentration range may be within the range of 70%, but the concentration may be as high as 70% if necessary. That is, according to the present invention, the concentration of ferromagnetic particles can be adjusted to a high concentration of up to 70% by using an intermediate medium in which ferromagnetic particles are dispersed in a low boiling point organic solvent, as described later. be able to. As a result, a magnetic fluid with extremely high magnetization can be obtained.
【００３０】本発明に用いられる強磁性体微粒子の分散
剤は、先に述べたキャリアとなる低揮発性有機溶媒との
親和性が良好な低分子ｉ！（５５０以下）のものが好ま
しい。例えば、オレイン酸又はその塩２石油スルホン酸
又はその塩５合成スルホン酸またはその塩、エイコシル
ナフタレンスルホン酸またはその塩、ポリブテンコハク
酸またはその塩、エライジン酸またはその塩、エルカ酸
またはその塩等の如く、カルボキシル基、ヒドロキシル
基、スルホン基等の極性基を有する炭化水素化合物であ
る陰イオン性界面活性剤とか、或いはまたポリオキシエ
チレンノニルフェニルエーテル等の如き非イオン性界面
活性剤とか、更にはアルキルジアミノエチルグリジンの
如く分子構造式に陽イオン部分と陰イオン部分とを伴に
持つ両性界面活性剤等から適宜選択して用いられる。The dispersant for the ferromagnetic fine particles used in the present invention is a low molecular weight i! that has good affinity with the low-volatile organic solvent that serves as the carrier mentioned above. (550 or less) is preferred. For example, oleic acid or its salt 2 Petroleum sulfonic acid or its salt 5 Synthetic sulfonic acid or its salt, eicosylnaphthalene sulfonic acid or its salt, polybutenesuccinic acid or its salt, elaidic acid or its salt, erucic acid or its salt, etc. Anionic surfactants which are hydrocarbon compounds having polar groups such as carboxyl group, hydroxyl group, sulfone group, etc., or nonionic surfactants such as polyoxyethylene nonylphenyl ether, etc. is appropriately selected from amphoteric surfactants having both a cationic moiety and an anionic moiety in their molecular structure, such as alkyldiaminoethylglydine.
【００３１】本発明の分散剤として、いわゆるカップリ
ング剤を用いることもできる。このカップリング剤とし
ては、例えば一般式Ｙｌ）Ｒ４−ＳｉＸ （Ｐは１以
上の整数、ｎは１〜３の整数）又はＲ４−ＳｉＸ （
ｎは１〜３の整数）で表すことができるシランカップリ
ング剤がある。ここに、式中のＹはビニル基、エポキシ
基、アミノ基、メルカプト基その他の有機官能基であり
、Ｒは例えばアルキル基の如き炭化水素基である。Ｘは
加水分解性の基であり、例えばメトキシ基（ＣＨ３０）
やエトキシ基（Ｃ２Ｈ５０）等のアルコキシ基（ＲＯ−
）である。
［００３２］ このシランカップリング剤のアルコシル
基は、水溶液中、空気中の水分又は無機物表面に吸着さ
れた水分により加水分解して、シラノール基（−８ｉ−
０Ｈ）を生成する。一方、強磁性体微粒子はその表面に
ＯＨ基を有しており（Ｍ−ＯＨ）、両者の間に脱水縮合
反応が生じてメタシロキサン結合（Ｓ ｉ−０−Ｍ）に
より化学的に結合するものと考えられる。
［００３３］一般式ＹｐＲ４−ＳｉＸ で表わされる
シランカップリング剤は例えばビニルトリエトキシシラ
ンであり、一般式Ｒ４−ＳｉＸ で表わせられるシラ
ンカップリング剤は例えばオクタデシルトリメトキシシ
ランである。
［００３４］前期のシランカップリング剤以外のカップ
リング剤としては、例えば、非水系に対して特に好適な
アセトアルコキシアルミニウムジイソプロピレートから
なるアルミニウム系カップリング剤や、チタネート系カ
ップリング剤、クロム系カップリング剤等が使用できる
。これらのものもその分子構造中に、−ＯＨ基と結合す
るアルコキシ基と有機物に親和する部分（例えば、アル
コキシアセト酢酸基）とを持っており、親水性固体であ
る強磁性体微粒子表面の一〇Ｈ基と化学結合して強固な
親油性皮膜を形成する機能を有する。
［００３５］カツプリング剤の添加量は、強磁性体微粒
子表面を単分子膜で完全に被覆する量が最適であるが、
強磁性体微粒子の比表面、水分含有量、シランの加水分
解性、膜形成状態の違い等を考慮して定められる。
［００３６］本発明の磁性流体組成物を製造するにあた
り、強磁性流体粒子中の分散性の悪い粒子を効率よく除
去して安定性の高い磁性流体を得ようとするならば、或
いはまたキャリア中に分散させる強磁性体微粒子の濃度
を高くして高磁化力を持つ磁性流体を得ようとするなら
ば、本出願人が先に提案した磁性流体の製造方法（特開
昭５８−１７４４９５号）によると効率的である。
［００３７］すなわち、強磁性体微粒子と分散剤とを、
まず沸点が８５℃以下のヘキサン、ベンゼン、シクロヘ
キサン、四塩化炭素、クロロホルム等の低沸点無極性有
機溶媒に加える。これにより表面を分散剤で被覆した強
磁性体微粒子が無極性低沸点有機溶媒中に分散された中
間媒体を得る。
［００３８］ この時、湿式法で得られる強磁性体微粒
子を用いるのであれば、強磁性体微粒子の懸濁液に所要
最の分散剤を加えて被覆相を形成し、いったん洗浄し、
乾燥して疎水性強磁性体微粒子を得た後、低沸点無極性
有機溶媒を加えても良い。
［００３９］いずれの工程を用いるかは、製品の種類。
使用目的、要求性能等に応じて選択される。次いで、強
磁性体微粒子表面に単分子吸着している分散剤以外の分
散剤（二相吸着している分散剤、低沸点無極性有機溶媒
中に溶解している分散剤）を除去するために、前期中間
媒体を洗浄する。強磁性体微粒子に分散剤が二相吸着す
ると、該粒子が親水性となり、粒子同士の凝集が生じる
。キャリア中に侵入した水分と親和性が高くなり、強磁
性体微粒子から分散剤が脱着する等おそれがある。また
、低沸点無極性有機溶媒中に磁性粒子に吸着していない
分散剤が存在すると、キャリアとなるべき低揮発性有機
溶媒（後述）中に分散剤が混入し、キャリアの水に対す
る親和性が高くなって磁性流体組成物の耐水性を低下さ
せる。そこで、これらの問題を解決することを意図して
、前期中間媒体を洗浄するのである。
［００４０１この洗浄液としては、低沸点（沸点が８５
℃以下）の極性有機溶媒である例えば、アルコール類（
メタノール、エタノール等）、ケトン類（アセトン。
エチルメチルケトン等）が使用できる。低沸点極性有機
溶媒で前期中間媒体を洗浄すると、磁性粒子に二相吸着
している分散剤、低沸点極性有機溶媒中に溶解している
分散剤を当該低沸点極性有機溶媒中に転溶して除去する
ことができる。
［００４１］ この場合、低沸点無極性有機溶媒と低沸
点極性有機溶媒の量の比率によって、混合後二相に分離
するものと均一に溶解するものがある。二相に分離する
ものは、低沸点極性有機溶媒を多く含む相を分離除去し
て、以下の工程を行うことができる。それに対して、均
一に溶解するものは、それによって洗浄された磁性流体
微粒子が凝集沈澱するのでろ過で回収後、乾燥し低沸点
無極性有機溶媒に再分散させてから以下の工程を行うこ
とができる。
［００４２１次に洗浄後の中間媒体中の分散性の悪い強
磁性体微粒子を５０００〜８０００Ｇの遠心力で遠心分
離して除く。低沸点無極性有機溶媒からなる中間媒体は
その粘度が極めて低いから、遠心分離を効率良く行うこ
とができる。
［００４３］尚、この遠心分離を前記中間媒体の洗浄前
に行うことも可能である。その後に、キャリアとしての
前記低揮発性有機溶媒を加えて混合し、その混合物を大
気中または減圧中で加熱して低沸点有機溶媒（前記低沸
点無極性有機溶媒及び洗浄の工程で混入した低沸点極性
有機溶媒）を蒸発する。尚、中間媒体を一旦加熱して低
沸点有機溶媒を蒸発させてから、強磁性体微粒子に低揮
発性有機溶媒を加え、必要に応じて更に低沸点有機溶媒
を蒸発させることもできる。かくして、極めて安定した
磁性流体の溶液とするものである。
［００４４］またこの場合、得られた磁性流体に、必要
に応じて更に前記中間媒体を加えては加熱することを繰
り返すことで、強磁性体微粒子が非常に高濃度でしかも
安定に分散された磁性流体を得ることも可能である。
［００４５１本発明の磁性流体組成物の製造法における
添加剤は、磁性流体の製造工程における途中の、中間媒
体を得る工程以降のどこで加えても良く、最後に得られ
た磁性流体に対して加えても良い。また、添加剤は直接
加えても良く、あるいは溶剤に予め溶解させたものを磁
性流体と混合し、その後該溶剤を蒸発除去するようにし
てもよい。この場合の溶剤としては、例えば以下のよう
なものが使用できる。
［００４６］ケロシン等の鉱油、ベンゼン、トルエン、
キシレン、アルコール、セロソルブ、エチルアセテート
、セロソルブアセテート、ＭＥＫ （メチルエチルケト
ン）、ＭＩＢＫ（メチルイソブチルケトン）、１，１゜
１−トリクロロエタン、クロロホルム、四塩化炭素、Ｄ
ＭＦ （ジメチルホルムアルデヒド）、酢酸エチル等。
［００４７］なお、添加剤を中間媒体工程において加え
る場合に、ヘキサンなどの中間媒体用の溶剤に溶解させ
たものを加えても良い。或いはまた、前記溶媒以外に、
先に述べた磁性流体のキャリア、すなわち種々の炭化水
素２合成油類及びエーテル類またはエステル類等の有機
溶媒と混合した添加剤を加えても良い。
［００４８］尚、本発明に係わる磁性流体組成物の製造
方法において、前記中間媒体を経ないことも可能である
。この場合は、強磁性体微粒子に対して、低沸点無極性
有機溶媒とこれと親和性のある親油性基を有する分散剤
とを加えて、該分散剤を強磁性体微粒子の表面に結合さ
せ、その後前記低沸点無極性有機溶媒を除去して前記分
散剤で表面が被覆された強磁性体微粒子を得て、該強磁
性体微粒子を低沸点極性有機溶媒を用いて洗浄して乾燥
させ、この磁性流体微粒子にキャリアとなる低揮発性有
機溶媒及び前記添加剤を加えて本発明に係わる磁性流体
組成物を製造することができる。
［００４９］A so-called coupling agent can also be used as a dispersant in the present invention. As this coupling agent, for example, the general formula Yl) R4-SiX (P is an integer of 1 or more, n is an integer of 1 to 3) or R4-SiX (
There are silane coupling agents that can be represented by (n is an integer of 1 to 3). Here, Y in the formula is a vinyl group, epoxy group, amino group, mercapto group or other organic functional group, and R is a hydrocarbon group such as an alkyl group. X is a hydrolyzable group, for example, a methoxy group (CH30)
Alkoxy groups (RO-
). [0032] The alkosyl group of this silane coupling agent is hydrolyzed by moisture in an aqueous solution, in the air, or moisture adsorbed on the surface of an inorganic substance to form a silanol group (-8i-
0H). On the other hand, ferromagnetic fine particles have OH groups on their surfaces (M-OH), and a dehydration condensation reaction occurs between the two, resulting in chemical bonding through metasiloxane bonds (S i-0-M). considered to be a thing. [0033] The silane coupling agent represented by the general formula YpR4-SiX is, for example, vinyltriethoxysilane, and the silane coupling agent represented by the general formula R4-SiX is, for example, octadecyltrimethoxysilane. [0034] Coupling agents other than the above-mentioned silane coupling agents include, for example, aluminum-based coupling agents made of acetalkoxyaluminum diisopropylate, which are particularly suitable for non-aqueous systems, titanate-based coupling agents, and chromium-based coupling agents. Coupling agents etc. can be used. These substances also have an alkoxy group that binds to an -OH group and a moiety that has an affinity for organic substances (for example, an alkoxyacetoacetic acid group) in their molecular structure, and a portion of the surface of the ferromagnetic fine particles, which is a hydrophilic solid, is present. 〇Has the function of chemically bonding with H groups to form a strong lipophilic film. [0035] The optimum amount of the coupling agent to be added is such that the surface of the ferromagnetic fine particles is completely covered with a monomolecular film.
It is determined by considering the specific surface of the ferromagnetic particles, water content, hydrolyzability of silane, differences in film formation state, etc. [0036] In producing the magnetic fluid composition of the present invention, if particles with poor dispersibility in the ferrofluid particles are to be efficiently removed to obtain a highly stable magnetic fluid, or if particles in the carrier are In order to obtain a magnetic fluid with a high magnetizing force by increasing the concentration of ferromagnetic fine particles dispersed in the ferromagnetic particles, the method for producing a magnetic fluid previously proposed by the present applicant (Japanese Patent Laid-Open No. 174495/1982) According to efficient. [0037] That is, the ferromagnetic fine particles and the dispersant,
First, it is added to a low-boiling nonpolar organic solvent such as hexane, benzene, cyclohexane, carbon tetrachloride, or chloroform, which has a boiling point of 85° C. or less. As a result, an intermediate medium is obtained in which fine ferromagnetic particles whose surfaces are coated with a dispersant are dispersed in a nonpolar, low-boiling organic solvent. [0038] At this time, if ferromagnetic fine particles obtained by a wet method are used, a required amount of dispersant is added to a suspension of ferromagnetic fine particles to form a coating phase, and once washed,
After drying to obtain hydrophobic ferromagnetic fine particles, a low-boiling nonpolar organic solvent may be added. [0039] Which process is used depends on the type of product. It is selected depending on the purpose of use, required performance, etc. Next, in order to remove dispersants other than the dispersant monomolecule adsorbed on the surface of the ferromagnetic fine particles (dispersant adsorbed in two phases, dispersant dissolved in a low-boiling nonpolar organic solvent). , wash the intermediate medium. When the dispersant is two-phase adsorbed onto the ferromagnetic fine particles, the particles become hydrophilic and agglomeration of the particles occurs. The dispersant may have a high affinity with the moisture that has entered the carrier, and the dispersant may be desorbed from the ferromagnetic fine particles. In addition, if a dispersant that is not adsorbed to the magnetic particles is present in the low-boiling nonpolar organic solvent, the dispersant will be mixed into the low-volatile organic solvent (described later) that should serve as the carrier, and the affinity of the carrier for water will be reduced. This increases the water resistance of the ferrofluid composition. Therefore, the intermediate medium is cleaned with the intention of solving these problems. [00401 This cleaning liquid has a low boiling point (boiling point of 85
For example, alcohols (
methanol, ethanol, etc.), ketones (acetone, ethyl methyl ketone, etc.) can be used. When the intermediate medium is washed with a low-boiling polar organic solvent, the dispersant adsorbed on the magnetic particles in two phases and the dispersant dissolved in the low-boiling polar organic solvent are transferred and dissolved into the low-boiling polar organic solvent. It can be removed by [0041] In this case, depending on the ratio of the amounts of the low-boiling nonpolar organic solvent and the low-boiling polar organic solvent, some of them separate into two phases after mixing, while others dissolve uniformly. For those that separate into two phases, the phase containing a large amount of low-boiling polar organic solvent can be separated and removed, and the following steps can be carried out. On the other hand, if the magnetic fluid particles are uniformly dissolved, the washed magnetic fluid particles will coagulate and precipitate, so after collecting them by filtration, drying and redispersing them in a low-boiling non-polar organic solvent, the following steps can be carried out. can. [00421] Next, the ferromagnetic fine particles with poor dispersibility in the intermediate medium after washing are removed by centrifugation at a centrifugal force of 5000 to 8000 G. Since the intermediate medium made of a low-boiling nonpolar organic solvent has an extremely low viscosity, centrifugation can be performed efficiently. [0043] Note that it is also possible to perform this centrifugation before washing the intermediate medium. After that, the low-volatile organic solvent as a carrier is added and mixed, and the mixture is heated in the air or under reduced pressure to remove the low-boiling organic solvent (the low-boiling non-polar organic solvent and the (boiling point polar organic solvent) is evaporated. It is also possible to heat the intermediate medium once to evaporate the low-boiling point organic solvent, then add the low-volatile organic solvent to the ferromagnetic fine particles, and further evaporate the low-boiling point organic solvent if necessary. This results in an extremely stable magnetic fluid solution. [0044] In this case, the ferromagnetic fine particles were stably dispersed at a very high concentration by repeating adding and heating the intermediate medium as necessary to the obtained magnetic fluid. It is also possible to obtain magnetic fluids. [00451 The additives in the method for producing a magnetic fluid composition of the present invention may be added at any point after the step of obtaining an intermediate medium during the manufacturing process of the magnetic fluid, and may be added to the magnetic fluid finally obtained. It's okay. Further, the additive may be added directly, or it may be dissolved in a solvent beforehand and mixed with the magnetic fluid, and then the solvent may be removed by evaporation. As the solvent in this case, for example, the following can be used. [0046] Mineral oil such as kerosene, benzene, toluene,
Xylene, alcohol, cellosolve, ethyl acetate, cellosolve acetate, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), 1,1゜1-trichloroethane, chloroform, carbon tetrachloride, D
MF (dimethyl formaldehyde), ethyl acetate, etc. [0047] When adding additives in the intermediate medium step, additives dissolved in a solvent for intermediate medium such as hexane may be added. Alternatively, in addition to the solvent,
Additives mixed with the magnetic fluid carriers mentioned above, ie various hydrocarbon 2 synthetic oils and organic solvents such as ethers or esters, may also be added. [0048] In the method for producing a magnetic fluid composition according to the present invention, it is also possible to omit the intermediate medium. In this case, a low-boiling nonpolar organic solvent and a dispersant having a lipophilic group with affinity for the solvent are added to the ferromagnetic particles, and the dispersant is bonded to the surface of the ferromagnetic particles. , then removing the low-boiling non-polar organic solvent to obtain ferromagnetic fine particles whose surfaces are coated with the dispersant, washing and drying the ferromagnetic fine particles using a low-boiling polar organic solvent, The magnetic fluid composition according to the present invention can be produced by adding a low-volatile organic solvent serving as a carrier and the above-mentioned additives to the magnetic fluid fine particles. [0049]
添加剤を工程の最後で加える磁性流体の製造の実施例：
まず、硫酸第１鉄と硫酸第２鉄とをそれぞれ０． ３ｍ
。
ｌづつ含む水溶液１１に、６ＮのＮａ０ＨａｑをｐＨが
１１以上になるまで加える。その後、その混合液を６０
℃で３０分間熟成してマグネタイトコロイドの水懸濁液
を得た。次いで室温下で水洗し、このスラリー中の電解
質を除去する。以上は湿式法によるマグネタイトコロイ
ドを製造する工程である。
［００５０１このようにして得たマグネタイトコロイド
液に、３ＮのＨＣｌａｑを加えてそのｐＨを３に調整し
た後、これに界面活性剤として合成スルホン酸ナトリウ
ムを４０ｇ添加し、６０℃で３０分間攪拌することによ
り、マグネタイト微粒子の表面に界面活性剤を吸着させ
た。その後静置して、液中のマグネタイト微粒子を凝集
沈降させ、その上澄み液を捨てる。更に新たな水を加え
て攪拌してから静置し、上澄み液を捨てる。この水洗を
数回繰り返して水溶液中の電解質を除去した後、濾過。
脱水、乾燥を行い、表面が界面活性剤で被覆された粉末
状のマグネタイト微粒子とした。
［００５１１次に、このマグネタイト粉末に低沸点無極
性有機溶媒としてヘキサンを加えて十分に振とつするこ
とにより、マグネタイト粒子がヘキサン中に分散した中
間媒体が得られた。
［００５２］得られたコロイド液に低沸点極性有機とし
てメタノールを加え、−度粒子を凝集沈澱させて、上澄
液を捨てる。これにより、微粒子に単分子吸着した分散
剤以外の余分な分散剤が除去される。
［００５３］その後、沈澱した微粒子を再皮ヘキサン中
に再分散させて中間媒体を得る。この中間媒体を遠心分
離機にかけて８０００Ｇの遠心力下で３０分間遠心分離
し、マグネタイト分散粒子のうちの比較的大きな分散性
の悪い粒子を沈降せしめて除去する。ついで、沈降せず
に残ったマグネタイト微粒子が分散している上澄み液を
ロータリエバポレータに移し、９０℃に保って低沸点有
機溶媒成分すなわちヘキサンを蒸発除去して、親油性の
マグネタイト微粒子を得た。
［００５４］ このマグネタイト微粒子を５ｇ採取し、
ヘキサン中に再分散させた後、これにキャリアとなるポ
リ−α−オレフィン（平均重合度：３量体）４ｇを加え
て混合する。この混合液をロータリエバポレータに移し
、９０℃に保って低沸点有機溶媒成分すなわちヘキサン
を蒸発除去した。その結果、マグネタイト微粒子はキャ
リア中に分散する。これを更に遠心分離機にかけ、８０
００Ｇの遠心力下に３０分間処理した。この操作により
非分散固形物は取り除かれ、極めて安定な磁性流体が得
られた。
［００５５１次いで、この磁性流体に添加剤としてポリ
ブテン（狭義）コハク酸（平均分子量１１００） ０．
５ｇを加えて、液温を６０℃にし、よく攪拌する。こ
のようにして本発明に係わる磁性流体組成物を得ること
ができた。
初期粘度の測定
次いで、このようにして得られた磁性流体組成物につい
ての初期粘度を測定したところ粘度は７０ｃｐ（４０℃
）であった。この粘度は、ポリブテンコハク酸を分散剤
とする磁性流体組成物（ポリブテンコハク酸を４５重量
％含有する、これ以外の強磁性体微粒子の種類及び含有
量、キャリアの種類は得られた磁性流体組成物と同じ）
の粘度（８００ｃｐ（４０℃）〕と比較して充分低粘度
であることが分かる。
耐水性の試験
次いで、５０ｍ１のビー力に、この実施例に係る磁性流
体組成物１０ｍ１を取り、温度８０℃、相対湿度７０％
の雰囲気に１００時間放置した。放置後の粘度を測定し
て粘度増加値を求めたところ１．５ｃｐ （４０℃）の
極めて僅かな値であった。これに対して、前記ポリブテ
ンコハク酸を添加しない磁性流体組成物（それ以外の成
分及び含有量は全て同一とする。）は、同様の条件下で
粘度増加値は２５ｃｐ（４０℃）であった。尚、耐水性
が悪いと強磁性体微粒子が凝集してゲル化することによ
り粘度が増加値が大きくなるものである。
［００５６］ ここにおける結果は、本発明に係る磁性
流体組成物中で、マグネタイト微粒子の凝集が生じてい
ないことを示している。従って、得られた磁性流体組成
物の耐水性が良好であることが分かる。
耐熱性の試験
複数個（１０〜２０個）の内径φ２０のシャーレに前記
得られた磁性流体組成物を０．８ｍｌずつ取り、１７０
℃の乾熱炉に放置した。−時間毎に一つずつのシャーレ
を取り出した。取り出したシャーレはしばらくの間（約
２時間）室温（約２０℃）下に放置した後、傾けて磁性
流体組成物の流動性の有無を確認した。流動性がなくな
るまでの加熱時間を、その試料磁性流体組成物の１７０
℃における固化時間として耐熱性評価の尺度とした。磁
性流体組成物の耐熱性が悪いと、強磁性体微粒子の凝集
が生じてゲル化し固化時間が短くなる。尚、比較のため
、前記ポリブテンコハク酸を添加しない磁性流体組成物
（それ以外の成分及び含有量はすべて同一とする）につ
いても同様の試験を行い固化時間を求めた。
［００５７］ この試験の結果、前記得られた磁性流体
組成物についての固化時間として２５時間を得た。これ
に対して、比較のための磁性流体組成物の同化時間とし
て９時間を得た。両者の固化時間を比較すると明らかな
ように 本発明に係わる磁性流体組成物の耐熱性が大き
く向上していることが分かる。
〔実施例２〕
工程の途中で添加剤を添加する実施例：実施例１と同様
の工程を経て、低沸点極性有機溶媒を用いて余分な活性
剤を除去した親油性のマグネタイト微粒子を得た。この
マグネタイト微粒子を５ｇ採取し、ヘキサン中に再分散
させ、再び中間媒体とした後、キャリアとなるポリ−α
−オレフィン（平均重合度＝３量体）４ｇを加えた。同
時にポリブテン（狭義）コハク酸（平均分子量１１００
）０．５ｇを加え混合する。この混合液をロータリエバ
ポレータに移し、９０℃に保って低沸点有機溶媒すなわ
ちヘキサンを蒸発除去した。その結果、マグネタイト微
粒子はキャリア中に分散する。これを更に遠心分離機に
かけ、８０００Ｇの遠心力下に３０分間処理した。この
処理により非分散固形物が除去され、マグネタイト微粒
子が安定して分散した磁性流体組成物を得ることができ
る。
（００５８１次いで、前記実施例１と同様の手法により
、初期粘度を測定し、併せて前記実施例１と同様の手法
により耐水性の試験、耐熱性の試験を行った。この結果
、初期粘度の値として７０ｃｐ（４０℃）を得、耐水性
の試験に関する粘度増加値として１． ５ｃｐ （４０
℃）を得、さらに耐熱性の試験に関する固化時間として
２５時間を得た。これらの値は、この実施例によっても
耐熱・耐水性に優れ、且つ低粘度な磁性流体組成物が得
られることを示している。そして、添加剤は製造工程の
途中で添加しても、工程の最後で添加したと同様の効果
が得られることを示している。
〔実施例３〕
添加剤の含有量と初期粘度・耐水性との関係：前記実施
例１の工程において、最後に加えられる添加剤（ポリブ
テンコハク酸）の添加濃度のみを変えて得られた磁性流
体組成物の初期粘度を測定し、同時に前記耐水性の試験
を行い、耐水性とポリブテンコハク酸との含有量との関
係について試験を行った。第１図にこの試験によって得
られた特性図を示す。
［００５９］第１図において、粘度変化率Ｐ （％）と
は、初期粘度＝Ｐｏ、耐水性試験後の粘度＝Ｐ＋ とじ
た時に、
Ｐ ＝ 〔（Ｐ＋ Ｐｏ ）／Ｐｏ Ｘ１００：］
を言う。
［００６０］初期粘度が低い程低トルク性に優れ、そし
て、粘度変化率が小さい程耐水性に優れていることにな
る。第１図から明らかなように、添加濃度が０．５〜３
０重量％において、初期粘度が低く、且つ粘度変化率が
小さい磁性流体組成物を得ることができる。
〔実施例４〕
添加剤の含有量と耐熱性との関係：
ポリブテンコハク酸の含有量を種々変える以外は前記実
施例１と同様の組成物を作成し、前記実施例１で述べた
耐熱性試験と同様の手法によりポリブテン（狭義）コハ
ク酸の含有量と固化時間との関係について試験を行った
。第２図にこの試験によって得られた特性図を示す。
［００６１１第２図から明らかなように、ポリブテンコ
ハク酸（添加剤）を加えることにより、ポリブテンコハ
ク酸を含有しない磁性流体組成物に対して固化時間が大
きく向上することが分かる。
〔実施例５〕
キャリアとしてポリ−α−オレフィンからオクタデシル
ジフェニルエーテルにした他は前記実施例２と同様にし
て磁性流体組成物を作成した。
（００６２］ この磁性流体組成物について初期粘度の
測定、前記実施例１で説明した耐水性試験、耐熱性試験
を行った。この結果、初期粘度の値として６５ｃｐ（４
０℃）を得、粘度増加値として１．Ｏｃｐ （４０℃）
を得、同化時間として４０時間得た。これらはいずれも
作成された磁性流体組成物の耐熱性・耐水性が良好で、
且つ低トルク性に優れていることを明らかにするもので
ある。
〔実施例６〕
前記実施例１と同様にしてマグネタイト粒子がヘキサン
中に分散した中間媒体を得た。次にこの中間媒体をロー
タリエバポレータに移し、９０℃に保って低沸点無極性
有機溶媒成分即ちヘキサンを蒸発除去した後、それに低
沸点極性有機溶媒としてメタノールを加えて余分な界面
活性剤を洗浄除去した。そのあと、洗浄されたマグネタ
イト微粒子をろ過して回収後、８０℃で３時間減圧乾燥
した。
［００６３］ このマグネタイト微粒子を１０ｇ採取し
、これにキャリアとしてオクタデシルジフェニルエーテ
ルを５ｇ、さらに添加剤としてポリブテン（狭義）スル
ホン酸ナトリウム（平均分子量５００）を０．５ｇを加
えた後、ボールミルで３時間粉砕処理を行った。これを
遠心分離機にかけ、８０００Ｇの遠心力下で５０分間処
理した。この操作により非分散固形物は取り除かれ、−
８０３Ｎａ基を含むポリブテン誘導体を含んだ極めて安
定な磁性流体が得られた。
［００６４］ この実施例によって得られた磁性流体組
成物について初期粘度の測定、前記実施例１で説明した
耐水性試験、耐熱性試験を行った。この結果、初期粘度
の値として６２ｃｐ（４０℃）を得、粘度増加値として
３、Ｏｃｐ （４０℃）を得、同化時間として２１時間
を得た。これらはいずれも作成された磁性流体組成物の
耐熱性・耐水性が良好で、且つ低トルク性に優れている
ことを実証するものである。
〔実施例７〕
キャリアをポリ−α−オレフィン、添加剤をポリイソブ
チレンコハク酸（平均分子量２０００）とした以外は、
前記実施例６と同様にして磁性流体組成物を作成した。
［００６５］ この実施例によって得られた磁性流体組
成物について初期粘度の測定、前記実施例１で説明した
耐水性試験、耐熱性試験を行った。この結果、初期粘度
の値として１００ｃｐ（４０℃）を得、粘度増加値とし
て１、Ｏｃｐ （４０℃）を得、固化時間として３０時
間を得た。これらはいずれも作成された磁性流体組成物
の耐熱性・耐水性が良好で、且つ低トルク性に優れてい
ることを実証するものである。
［００６６］尚、本発明に係わる磁性流体組成物に、導
電性等の所望の特性を付与するために、各種の特性剤を
適宜含有させることが可能である。
［００６７］Example of manufacturing a ferrofluid where additives are added at the end of the process:
First, ferrous sulfate and ferric sulfate were added at 0.00% each. 3m
. 6N Na0Haq is added to the aqueous solution 11 containing 1 liter each until the pH becomes 11 or higher. Then, add the mixture to 60
Aqueous suspension of magnetite colloid was obtained by aging at ℃ for 30 minutes. Next, the slurry is washed with water at room temperature to remove the electrolyte in this slurry. The above is a process for producing magnetite colloid by a wet method. [00501 3N HClaq was added to the magnetite colloid solution obtained in this way to adjust the pH to 3, and then 40 g of synthetic sodium sulfonate was added as a surfactant, and the mixture was stirred at 60°C for 30 minutes. As a result, the surfactant was adsorbed onto the surface of the magnetite fine particles. Thereafter, the liquid is left to stand still to allow the fine magnetite particles in the liquid to coagulate and settle, and the supernatant liquid is discarded. Add more water, stir, let stand, and discard the supernatant liquid. After repeating this water washing several times to remove the electrolyte in the aqueous solution, it is filtered. Dehydration and drying were performed to obtain powdery magnetite fine particles whose surfaces were coated with a surfactant. [00511] Next, by adding hexane as a low-boiling nonpolar organic solvent to this magnetite powder and thoroughly shaking it, an intermediate medium in which magnetite particles were dispersed in hexane was obtained. [0052] Methanol is added to the obtained colloidal liquid as a low-boiling polar organic to coagulate and precipitate the particles, and the supernatant liquid is discarded. As a result, excess dispersant other than the dispersant monomolecularly adsorbed on the fine particles is removed. [0053] Thereafter, the precipitated microparticles are redispersed in reskinned hexane to obtain an intermediate medium. This intermediate medium is centrifuged for 30 minutes under a centrifugal force of 8000 G to sediment and remove relatively large particles with poor dispersibility among the magnetite dispersed particles. Next, the supernatant liquid in which the magnetite fine particles that remained without sedimentation were dispersed was transferred to a rotary evaporator and kept at 90° C. to evaporate and remove the low-boiling organic solvent component, that is, hexane, to obtain lipophilic magnetite fine particles. [0054] 5 g of this magnetite fine particles were collected,
After redispersing in hexane, 4 g of poly-α-olefin (average degree of polymerization: trimer) serving as a carrier is added and mixed. This mixed solution was transferred to a rotary evaporator and maintained at 90° C. to evaporate and remove the low-boiling organic solvent component, ie, hexane. As a result, the magnetite fine particles are dispersed in the carrier. This was further centrifuged and
It was treated under centrifugal force of 00G for 30 minutes. This operation removed non-dispersed solids and yielded an extremely stable magnetic fluid. [00551 Next, polybutene (in a narrow sense) succinic acid (average molecular weight 1100) was added to this magnetic fluid as an additive.
Add 5 g, raise the liquid temperature to 60°C, and stir well. In this way, a magnetic fluid composition according to the present invention could be obtained. Measurement of Initial Viscosity Next, the initial viscosity of the thus obtained magnetic fluid composition was measured and found to be 70 cp (at 40°C).
)Met. This viscosity is determined by the magnetic fluid composition using polybutene succinic acid as a dispersant (containing 45% by weight of polybutene succinic acid, the type and content of other ferromagnetic fine particles, and the type of carrier). (same as thing)
It can be seen that the viscosity is sufficiently low compared to the viscosity of (800 cp (40 °C))].Water resistance test Next, 10 ml of the magnetic fluid composition according to this example was placed in a bead of 50 ml, and the temperature was 80 °C. , relative humidity 70%
It was left in the atmosphere for 100 hours. When the viscosity after standing was measured and the viscosity increase value was determined, it was an extremely small value of 1.5 cp (40° C.). In contrast, the magnetic fluid composition without the addition of polybutenesuccinic acid (all other components and contents are the same) had a viscosity increase of 25 cp (40°C) under similar conditions. . Note that if the water resistance is poor, the ferromagnetic fine particles aggregate and gel, resulting in a large increase in viscosity. [0056] The results herein demonstrate that no agglomeration of magnetite particulates occurs in the magnetic fluid compositions of the present invention. Therefore, it can be seen that the obtained magnetic fluid composition has good water resistance. Heat resistance test 0.8 ml of the obtained magnetic fluid composition was placed in multiple (10 to 20) Petri dishes with an inner diameter of φ20, and
It was left in a dry heat oven at ℃. - One petri dish was taken out every hour. The Petri dish taken out was left at room temperature (about 20° C.) for a while (about 2 hours) and then tilted to check whether the magnetic fluid composition had fluidity. The heating time until the sample magnetic fluid composition loses its fluidity is 170%.
The solidification time at °C was used as a measure of heat resistance evaluation. If the heat resistance of the magnetic fluid composition is poor, the ferromagnetic fine particles will aggregate and gel, resulting in a short solidification time. For comparison, a similar test was also conducted on a magnetic fluid composition to which the polybutenesuccinic acid was not added (all other components and contents were the same), and the solidification time was determined. [0057] This test resulted in a solidification time of 25 hours for the resulting magnetic fluid composition. In contrast, an assimilation time of 9 hours was obtained for the comparative ferrofluid composition. As is clear from comparing the solidification times of the two, it can be seen that the heat resistance of the magnetic fluid composition according to the present invention is greatly improved. [Example 2] Example of adding additives during the process: Through the same process as in Example 1, lipophilic magnetite fine particles were obtained from which excess activator was removed using a low-boiling polar organic solvent. . 5g of these magnetite fine particles were collected, redispersed in hexane, used as an intermediate medium again, and then poly-α used as a carrier.
- 4 g of olefin (average degree of polymerization = trimer) was added. At the same time, polybutene (narrowly defined) succinic acid (average molecular weight 1100
) Add 0.5g and mix. This mixed solution was transferred to a rotary evaporator and kept at 90° C. to evaporate and remove the low boiling point organic solvent, ie, hexane. As a result, the magnetite fine particles are dispersed in the carrier. This was further centrifuged and processed under a centrifugal force of 8000G for 30 minutes. This treatment removes non-dispersed solids and provides a magnetic fluid composition in which fine magnetite particles are stably dispersed. (00581) Next, the initial viscosity was measured using the same method as in Example 1, and a water resistance test and a heat resistance test were also conducted using the same method as in Example 1. As a result, the initial viscosity A value of 70 cp (at 40 °C) was obtained and a viscosity increase value of 1.5 cp (40
°C) and a solidification time of 25 hours for the heat resistance test. These values indicate that a magnetic fluid composition having excellent heat resistance and water resistance and low viscosity can be obtained also in this example. This shows that even if the additive is added in the middle of the manufacturing process, the same effect can be obtained as if it were added at the end of the process. [Example 3] Relationship between additive content and initial viscosity/water resistance: Magnetism obtained by changing only the concentration of the additive (polybutene succinic acid) added last in the process of Example 1 The initial viscosity of the fluid composition was measured, and at the same time the water resistance test was conducted to examine the relationship between water resistance and the polybutene succinic acid content. Figure 1 shows a characteristic diagram obtained through this test. [0059] In Fig. 1, the viscosity change rate P (%) means that initial viscosity = Po, viscosity after water resistance test = P+, and when closed, P = [(P+ Po )/Po X100:]
say. [0060] The lower the initial viscosity, the better the low torque property, and the lower the viscosity change rate, the better the water resistance. As is clear from Figure 1, the additive concentration is 0.5 to 3.
At 0% by weight, a magnetic fluid composition with a low initial viscosity and a small rate of viscosity change can be obtained. [Example 4] Relationship between additive content and heat resistance: The same composition as in Example 1 was prepared except that the content of polybutenesuccinic acid was varied, and the heat resistance as described in Example 1 was obtained. A test was conducted on the relationship between the content of polybutene (narrowly defined) succinic acid and solidification time using the same method as in the test. Figure 2 shows a characteristic diagram obtained through this test. [00611 As can be seen from FIG. 2, the addition of polybutene succinic acid (additive) significantly improves the setting time relative to the magnetic fluid composition that does not contain polybutene succinic acid. [Example 5] A magnetic fluid composition was prepared in the same manner as in Example 2 except that octadecyl diphenyl ether was used as the carrier instead of poly-α-olefin. (0062) This magnetic fluid composition was subjected to measurement of initial viscosity, water resistance test, and heat resistance test as explained in Example 1. As a result, the initial viscosity value was 65 cp (4
0°C), and the viscosity increase value was 1. Ocp (40℃)
was obtained, and the assimilation time was 40 hours. All of these have good heat resistance and water resistance of the magnetic fluid compositions created.
It also reveals that it has excellent low torque performance. [Example 6] An intermediate medium in which magnetite particles were dispersed in hexane was obtained in the same manner as in Example 1 above. Next, this intermediate medium was transferred to a rotary evaporator and kept at 90°C to evaporate and remove the low-boiling non-polar organic solvent component, i.e., hexane, and then methanol was added as a low-boiling polar organic solvent to wash off the excess surfactant. did. Thereafter, the washed magnetite fine particles were collected by filtration, and then dried under reduced pressure at 80° C. for 3 hours. [0063] 10 g of these magnetite fine particles were collected, 5 g of octadecyl diphenyl ether was added as a carrier, and 0.5 g of sodium polybutene (narrowly defined) sulfonate (average molecular weight 500) was added as an additive, and then pulverized in a ball mill for 3 hours. processed. This was centrifuged and processed under a centrifugal force of 8000G for 50 minutes. This operation removes undispersed solids and -
An extremely stable magnetic fluid containing a polybutene derivative containing 803Na groups was obtained. [0064] The magnetic fluid composition obtained in this example was subjected to measurement of initial viscosity, water resistance test, and heat resistance test as explained in Example 1 above. As a result, the initial viscosity value was 62 cp (40°C), the viscosity increase value was 3.Ocp (40°C), and the assimilation time was 21 hours. All of these demonstrate that the prepared magnetic fluid composition has good heat resistance and water resistance, and is excellent in low torque performance. [Example 7] Except that the carrier was poly-α-olefin and the additive was polyisobutylene succinic acid (average molecular weight 2000),
A magnetic fluid composition was prepared in the same manner as in Example 6 above. [0065] The magnetic fluid composition obtained in this example was subjected to measurement of initial viscosity, water resistance test, and heat resistance test as explained in Example 1 above. As a result, the initial viscosity value was 100 cp (40°C), the viscosity increase value was 1.0 cp (40°C), and the solidification time was 30 hours. All of these demonstrate that the prepared magnetic fluid composition has good heat resistance and water resistance, and is excellent in low torque performance. [0066] In order to impart desired properties such as electrical conductivity to the magnetic fluid composition according to the present invention, it is possible to appropriately contain various properties agents. [0067]
【発明の効果】以上説明したように本発明に係わる磁性
流体組成物は、低揮発性有機溶媒からなる分散媒と、該
有機溶媒と親和性のある親油基及び極性基を有する低分
子景の分散剤と、該分散剤で表面を被覆され前記有機溶
媒中に分散された強磁性体微粒子と、高分子鎖の親油基
及び極性基を有し、前記分散媒中に加えられる添加剤と
、から本質的になる構成とした。従って、耐熱性、耐水
性に優れ、且つ、低粘度でもある磁性流体組成物を提供
することができる、という効果を奏する。
［００６８］そして、本発明に係わる磁性流体組成物の
製造方法によれば、単分子吸着する分散剤以外の分散剤
を洗浄除去し、分散剤で表面が被覆された強磁性体微粒
子に対して、直接に、又は該強磁性流体微粒子が低沸点
有機溶媒に分散された中間媒体を介して、低揮発性有機
溶媒を混合する工程に、前記添加剤を加える工程を付加
したものであるから、前記添加剤を分散剤としてではな
くキャリア中に添加剤として含有させることができ、そ
の結果、耐熱性、耐水性に優れ、且つ、低粘度でもある
磁性流体組成物を特別の製造設備投資を必要とすること
なく、既存の設備で安価に製造することができる、とい
う効果を奏する。Effects of the Invention As explained above, the magnetic fluid composition according to the present invention comprises a dispersion medium made of a low-volatility organic solvent, and a low molecular weight group having a lipophilic group and a polar group having an affinity for the organic solvent. a dispersant, ferromagnetic fine particles whose surfaces are coated with the dispersant and dispersed in the organic solvent, and an additive having a lipophilic group and a polar group in a polymer chain and added to the dispersion medium. The structure consists essentially of this. Therefore, it is possible to provide a magnetic fluid composition that has excellent heat resistance and water resistance, and also has low viscosity. [0068] According to the method for producing a magnetic fluid composition according to the present invention, the dispersant other than the dispersant adsorbing single molecules is washed and removed, and the ferromagnetic fine particles whose surfaces are coated with the dispersant are , the step of adding the additive is added to the step of mixing a low-volatile organic solvent directly or through an intermediate medium in which the ferrofluid fine particles are dispersed in a low-boiling point organic solvent, The additives can be contained as additives in the carrier rather than as dispersants, and as a result, magnetic fluid compositions with excellent heat resistance, water resistance, and low viscosity require special manufacturing equipment investment. This has the effect that it can be manufactured at low cost using existing equipment without having to do so.
【図１】 ポリブテンコハク酸（添加剤）の磁性流体に
対する添加濃度と粘度変化率・初期粘度との関係を示す
特性図である。FIG. 1 is a characteristic diagram showing the relationship between the concentration of polybutenesuccinic acid (additive) added to a magnetic fluid and the viscosity change rate/initial viscosity.
【図２】 ポリブテンコハク酸（添加剤）の磁性流体に
対する添加濃度と固化時間との関係を示す特性図である
。
フロントページの続きFIG. 2 is a characteristic diagram showing the relationship between the concentration of polybutenesuccinic acid (additive) added to the magnetic fluid and the solidification time. Continuation of front page
Claims (9)
有機溶媒と親和性のある親油基及び極性基を有する低分
子量の分散剤と、該分散剤で表面が被覆され前記有機溶
媒中に分散された強磁性体微粒子と、高分子鎖の親油基
及び極性基を有し、前記分散媒中に加えられる添加剤と
、から本質的になることを特徴とする磁性流体組成物。1. A dispersion medium consisting of a low-volatile organic solvent, a low molecular weight dispersant having a lipophilic group and a polar group that have affinity with the organic solvent, and a surface coated with the dispersant and the organic solvent. A magnetic fluid composition consisting essentially of ferromagnetic fine particles dispersed therein, and an additive having a lipophilic group and a polar group in a polymer chain and added to the dispersion medium. .
〜１５００の炭化水素からなることを特徴とする請求項
１記載の磁性流体組成物。2. The polymer chain of the additive has 25 carbon atoms.
2. The magnetic fluid composition of claim 1, wherein the magnetic fluid composition is comprised of ˜1500 hydrocarbons.
ン、ポリプロピレン、ポリブテン、ポリブタジェン、ポ
リ（１−デセン）、ポリスチレンの少なくとも一つ及び
それぞれのモノマによるコポリマであることを特徴とす
る請求項２記載の磁性流体組成物。3. The hydrocarbon chain of the additive is a copolymer of at least one of polyethylene, polypropylene, polybutene, polybutadiene, poly(1-decene), and polystyrene and a monomer thereof. The magnetic fluid composition described.
及び／又はスルホン基であることを特徴とする請求項（
１）ないし３のいずれか１項に記載の磁性流体組成物。4. Claim 4, wherein the polar group of the additive is a carboxyl group and/or a sulfone group.
The magnetic fluid composition according to any one of items 1) to 3.
００であることを特徴とする請求項１ないし４のいずれ
か１項に記載の磁性流体組成物。5. The additive has a molecular weight of 500 to 200.
The magnetic fluid composition according to any one of claims 1 to 4, characterized in that the magnetic fluid composition is 00.
％であることを特徴とする請求項１ないし５のいずれか
１項に記載の磁性流体組成物。6. The magnetic fluid composition according to claim 1, wherein the content of the additive is 0.5 to 30% by weight.
有機溶媒と、これと親和性のある親油基を有する分散剤
とを加えて、該分散剤で強磁性体微粒子の表面に結合さ
せ、その後前記低沸点無極性有機溶媒を除去して前記分
散剤で表面が被覆された強磁性体微粒子を得る工程と、
この強磁性体微粒子を低沸点極性有機溶媒を用いて洗浄
する工程と、該洗浄後の強磁性体微粒子に低揮発性有機
溶媒と高分子鎖の親油基及び極性基を有する添加剤とを
加えて混合する工程と、を有することを特徴とする磁性
流体組成物の製造方法。7. A low-boiling nonpolar organic solvent and a dispersant having a lipophilic group with affinity for the organic solvent are added to the ferromagnetic particles, and the surface of the ferromagnetic particles is coated with the dispersant. bonding, and then removing the low-boiling nonpolar organic solvent to obtain ferromagnetic fine particles whose surfaces are coated with the dispersant;
A step of washing the ferromagnetic fine particles using a low-boiling polar organic solvent, and adding a low-volatile organic solvent and an additive having a lipophilic group and a polar group in a polymer chain to the ferromagnetic fine particles after washing. 1. A method for producing a magnetic fluid composition, further comprising the step of mixing.
有機溶媒と、これと親和性のある親油基を有して強磁性
体微粒子の表面を被覆する分散剤とを加えることにより
、該分散剤で表面を被覆された強磁性体微粒子が前記低
沸点無極性有機溶媒中に均一に分散された中間媒体を得
る工程と、該中間媒体を低沸点極性有機溶媒で洗浄する
工程と、該洗浄前又は洗浄後の中間媒体中の分散性の悪
い前記強磁性体微粒子を分離する工程と、当該分離後中
間媒体に低揮発性有機溶媒を加えて混合物とする工程と
、該混合物を加熱して前記低沸点有機溶媒を蒸発分離せ
しめて磁性流体を得る工程と、該磁性流体に高分子鎖の
親油基及び極性基を有する添加剤を加える工程と、を有
することを特徴とする磁性流体組成物の製造方法。[Claim 8] By adding to the ferromagnetic fine particles a low boiling point non-polar organic solvent and a dispersing agent having a lipophilic group having an affinity for the solvent and coating the surface of the ferromagnetic fine particles. , a step of obtaining an intermediate medium in which ferromagnetic fine particles whose surfaces are coated with the dispersant are uniformly dispersed in the low-boiling non-polar organic solvent; and a step of washing the intermediate medium with a low-boiling polar organic solvent. , a step of separating the ferromagnetic fine particles with poor dispersibility in the intermediate medium before or after the washing, a step of adding a low-volatile organic solvent to the intermediate medium after separation to form a mixture, and a step of preparing the mixture. The method is characterized by comprising a step of heating to evaporate and separate the low-boiling point organic solvent to obtain a magnetic fluid, and a step of adding an additive having a lipophilic group and a polar group of a polymer chain to the magnetic fluid. Method for manufacturing a magnetic fluid composition.
媒を加えて混合物とする工程で行う、ことを特徴とする
請求項８記載の磁性流体組成物の製造方法。9. The method for producing a magnetic fluid composition according to claim 8, wherein the additive is added in a step of adding the low-volatility organic solvent to form a mixture.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3023262A JPH079843B2 (en) | 1990-02-20 | 1991-02-18 | Magnetic fluid composition and method for producing the same |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2-38705 | 1990-02-20 | ||
| JP3870590 | 1990-02-20 | ||
| JP3023262A JPH079843B2 (en) | 1990-02-20 | 1991-02-18 | Magnetic fluid composition and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04211104A true JPH04211104A (en) | 1992-08-03 |
| JPH079843B2 JPH079843B2 (en) | 1995-02-01 |
Family
ID=26360578
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3023262A Expired - Fee Related JPH079843B2 (en) | 1990-02-20 | 1991-02-18 | Magnetic fluid composition and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH079843B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003513156A (en) * | 1999-10-28 | 2003-04-08 | 株式会社フェローテック | Improved magnetic fluid composition and manufacturing method |
| JP2004075530A (en) * | 2002-07-31 | 2004-03-11 | General Electric Co <Ge> | Nanoparticle having inorganic core |
| WO2016104534A1 (en) * | 2014-12-26 | 2016-06-30 | ソマール株式会社 | Sealing member and sealing structure |
-
1991
- 1991-02-18 JP JP3023262A patent/JPH079843B2/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003513156A (en) * | 1999-10-28 | 2003-04-08 | 株式会社フェローテック | Improved magnetic fluid composition and manufacturing method |
| JP4869527B2 (en) * | 1999-10-28 | 2012-02-08 | 株式会社フェローテック | Improved magnetic fluid composition and manufacturing method |
| JP2004075530A (en) * | 2002-07-31 | 2004-03-11 | General Electric Co <Ge> | Nanoparticle having inorganic core |
| JP4713067B2 (en) * | 2002-07-31 | 2011-06-29 | ゼネラル・エレクトリック・カンパニイ | Method for forming nanoparticles |
| WO2016104534A1 (en) * | 2014-12-26 | 2016-06-30 | ソマール株式会社 | Sealing member and sealing structure |
| CN107110372A (en) * | 2014-12-26 | 2017-08-29 | 索马龙株式会社 | Containment member and seal construction |
| JPWO2016104534A1 (en) * | 2014-12-26 | 2017-10-05 | ソマール株式会社 | Seal member and seal structure |
| CN107110372B (en) * | 2014-12-26 | 2019-12-27 | 索马龙株式会社 | Sealing member and sealing structure |
| TWI683970B (en) * | 2014-12-26 | 2020-02-01 | 日商索馬龍股份有限公司 | Sealing member and sealed structure |
| US10663065B2 (en) | 2014-12-26 | 2020-05-26 | Somar Corporation | Sealing member and sealing structure |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH079843B2 (en) | 1995-02-01 |
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