JP7383395B2 - magnetic fluid - Google Patents
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- JP7383395B2 JP7383395B2 JP2019086437A JP2019086437A JP7383395B2 JP 7383395 B2 JP7383395 B2 JP 7383395B2 JP 2019086437 A JP2019086437 A JP 2019086437A JP 2019086437 A JP2019086437 A JP 2019086437A JP 7383395 B2 JP7383395 B2 JP 7383395B2
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- 239000011553 magnetic fluid Substances 0.000 title claims description 42
- 239000006249 magnetic particle Substances 0.000 claims description 60
- 229920002545 silicone oil Polymers 0.000 claims description 44
- 239000004094 surface-active agent Substances 0.000 claims description 33
- -1 polysiloxane Polymers 0.000 claims description 13
- 229920001296 polysiloxane Polymers 0.000 claims description 10
- 125000000962 organic group Chemical group 0.000 claims description 9
- 239000003208 petroleum Substances 0.000 claims description 7
- 125000000217 alkyl group Chemical group 0.000 claims description 6
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 4
- 230000005415 magnetization Effects 0.000 claims description 4
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 2
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 2
- 239000002245 particle Substances 0.000 description 13
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 8
- 239000006185 dispersion Substances 0.000 description 7
- 230000004043 responsiveness Effects 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 230000001747 exhibiting effect Effects 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 229910018557 Si O Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000005303 antiferromagnetism Effects 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 239000004205 dimethyl polysiloxane Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 230000005307 ferromagnetism Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910001337 iron nitride Inorganic materials 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 230000005408 paramagnetism Effects 0.000 description 1
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Inorganic materials [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
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Description
本発明は、シリコーンオイル中に磁性粒子群を分散させてなる磁性流体に関する。 The present invention relates to a magnetic fluid made by dispersing magnetic particles in silicone oil.
近年、温度による粘性変化を抑えた磁性流体としてシリコーンオイルを基材として採用することが行われている（特許文献１参照）。この磁性流体では、磁性粒子との親和性を有する第１界面活性剤およびシリコーンオイルとの親和性を有する第２界面活性剤という２種類の界面活性剤で覆うことにより、磁性粒子のシリコーンオイル中での分散性を持たせている。 In recent years, silicone oil has been used as a base material for magnetic fluids that suppress changes in viscosity due to temperature (see Patent Document 1). In this magnetic fluid, magnetic particles are coated with two types of surfactants: a first surfactant that has an affinity for magnetic particles and a second surfactant that has an affinity for silicone oil. It has a dispersion property.
しかし、上記磁性流体では、シリコーンオイルに分散させる磁性粒子の数に応じて界面活性剤の占める領域も大きくなりやすいため、磁性流体としての粘度が高くなりやすい。磁性流体は、磁場勾配の影響を受ける環境で使用されるものであり、磁場の変化を受けて磁性粒子が偏在してしまうことのないよう、より多くの磁性粒子を分散させておくことが望ましい一方で、磁性流体としての応答性という点では粘度が不必要に高くなることは望ましくない。粘度に応じてシリコーンオイル中で磁性流体が受ける抵抗も大きくなり、磁場の変化に対する応答が安定しなくなるなど磁場環境下の分散性が低下するためである。 However, in the magnetic fluid described above, the area occupied by the surfactant tends to increase depending on the number of magnetic particles dispersed in silicone oil, so the viscosity of the magnetic fluid tends to increase. Magnetic fluids are used in environments where they are affected by magnetic field gradients, and it is desirable to have as many magnetic particles dispersed in order to prevent magnetic particles from becoming unevenly distributed due to changes in the magnetic field. On the other hand, in terms of responsiveness as a magnetic fluid, it is undesirable for the viscosity to become unnecessarily high. This is because the resistance that the magnetic fluid receives in silicone oil increases depending on the viscosity, and the dispersibility in a magnetic field environment decreases, such as the response to changes in the magnetic field becoming unstable.
そのため、上記のように２つの界面活性剤で磁性粒子を覆う磁性流体では、磁性粒子の数に応じて粘度が高くなりやすいという点で、磁性粒子を増やしにくく、使用環境に求められる粘度と応答性を両立できない場合がある。このことは、磁性流体としての使用環境が限定されることを意味している。 Therefore, in a magnetic fluid in which magnetic particles are covered with two surfactants as described above, the viscosity tends to increase depending on the number of magnetic particles, so it is difficult to increase the number of magnetic particles, and it is difficult to increase the viscosity and response required for the usage environment. Sometimes it is not possible to balance gender. This means that the environment in which it can be used as a magnetic fluid is limited.
本発明は、上記課題を解決するためになされたものであり、使用環境に求められる粘度と応答性を両立できる磁性流体を提供することである。 The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a magnetic fluid that can achieve both the viscosity and responsiveness required by the usage environment.
上記課題を解決するための第１局面は、無機質のシロキサン結合に有機基の側鎖を有するポリシロキサンからなるシリコーンオイルと、前記シリコーンオイル中に分散された複数の磁性粒子からなる磁性粒子群と、前記磁性粒子それぞれの表面を覆う石油系の界面活性剤と、からなり、前記シリコーンオイルには、ポリシロキサンの有機基としてアルキル基、芳香族基、またはそれらを組み合わせた官能基が採用されている磁性流体である。 A first aspect of solving the above problem is to use a silicone oil made of polysiloxane having an organic group side chain in an inorganic siloxane bond, and a magnetic particle group made of a plurality of magnetic particles dispersed in the silicone oil. , a petroleum-based surfactant that covers the surface of each of the magnetic particles, and the silicone oil includes an alkyl group, an aromatic group, or a functional group combining them as an organic group of the polysiloxane. It is a magnetic fluid.
この局面では、以下に示す第２局面のようにしてもよい。
第２局面において、前記シリコーンオイルには、ポリシロキサンの有機基としてエチル基が採用されている。
In this aspect, the second aspect shown below may be adopted.
In a second aspect, the silicone oil employs an ethyl group as an organic group of polysiloxane.
本願出願人は、ポリシロキサンの有機基を適切に選択したシリコーンオイルを用いることで、このシリコーンオイルと石油系の界面活性剤で覆われた磁性粒子との親和性により、シリコーンオイル中での磁性粒子の分散性（均一に分散して偏りにくい性能）を持たせられることを見出している。 By using silicone oil in which the organic groups of polysiloxane are appropriately selected, the applicant has discovered that magnetic particles in the silicone oil can be generated due to the affinity between this silicone oil and magnetic particles covered with a petroleum-based surfactant. It has been discovered that particles can be made to have good dispersibility (uniformly dispersed performance that is less likely to be biased).
そのため、上記各局面の磁性流体であれば、１種類の界面活性剤のみであっても磁性粒子のシリコーンオイル中での分散性を持たせることができ、２種類の界面活性剤を使用する場合と比べて、磁性粒子の数が同数であれば、磁性粒子の数に応じて界面活性剤の占める領域が大きくなりにくく、磁性流体としての粘度も高くなりにくい。 Therefore, if the magnetic fluid meets each of the above aspects, it is possible to make the magnetic particles dispersible in silicone oil even if only one type of surfactant is used, and when two types of surfactants are used. In comparison, if the number of magnetic particles is the same, the area occupied by the surfactant is less likely to increase in proportion to the number of magnetic particles, and the viscosity of the magnetic fluid is less likely to increase.
このように、上記各局面の磁性流体では、シリコーンオイルに分散させる磁性粒子を増やしても粘度が高くなりにくいため、使用環境に求められる粘度と応答性を両立することが可能となる結果、使用環境の選択肢を増やすことができる。 In this way, with the magnetic fluids in each of the above aspects, the viscosity does not easily increase even if the number of magnetic particles dispersed in silicone oil is increased, so it is possible to achieve both the viscosity and responsiveness required for the usage environment, and as a result, the use You can increase your environmental options.
また、上記局面の磁性流体は、以下に示す第３局面のようにしてもよい。
第３局面においては、前記磁性粒子群は、単位体積あたりに分散された磁性粒子の粒子量に応じた飽和磁化が１０ｍＴ以上となる量だけ前記シリコーンオイル中に分散されている。
Further, the magnetic fluid according to the above aspect may be configured as in the third aspect described below.
In a third aspect, the magnetic particles are dispersed in the silicone oil in an amount such that the saturation magnetization according to the amount of magnetic particles dispersed per unit volume is 10 mT or more.
この局面の磁性流体では、磁性粒子群の分散量を１０ｍＴ以上に増やしたとしても、磁性流体としての粘度を１０００ｍＰａ．ｓを超えない範囲とすることができる。 In the magnetic fluid of this aspect, even if the amount of dispersion of the magnetic particle group is increased to 10 mT or more, the viscosity of the magnetic fluid is 1000 mPa. It can be set within a range not exceeding s.
以下に本発明の実施形態を図面と共に説明する。
（１）全体構成
磁性流体は、ポリシロキサンからなるシリコーンオイルと、シリコーンオイル中に分散された複数の磁性粒子からなる磁性粒子群と、磁性粒子それぞれの表面を覆う界面活性剤と、からなる。
Embodiments of the present invention will be described below with reference to the drawings.
(1) Overall configuration The magnetic fluid consists of silicone oil made of polysiloxane, a magnetic particle group made of a plurality of magnetic particles dispersed in the silicone oil, and a surfactant that covers the surface of each magnetic particle.
シリコーンオイルは、無機質のシロキサン結合に有機基の側鎖を有するポリシロキサンからなり、この有機基としては、エチル基、プロピル基、ブチル基といった直鎖型・分岐型の標準的なアルキル基、フェニル基などの芳香族基、それらを組み合わせた官能基を採用することができる。シリコーンオイルの典型的な化学式は、以下のとおりである。なお、下記化学式におけるＲはアルキル基またはフェニル基である。 Silicone oil is made of polysiloxane that has organic group side chains attached to inorganic siloxane bonds, and these organic groups include standard linear and branched alkyl groups such as ethyl, propyl, and butyl groups, and phenyl groups. Aromatic groups such as groups, and functional groups that are a combination of these groups can be employed. A typical chemical formula for silicone oil is as follows: In addition, R in the following chemical formula is an alkyl group or a phenyl group.
ここで、有機基としてエチル基を採用したポリジエチルシロキサンとしては、シロキサンの重合度合いに応じた動粘度のものを用いることができる。具体的には、米国Ｇｅｌｅｓｔ社製のポリジエチルシロキサン（製品コードＤＥＳ－Ｔ１１、ＤＥＳ－Ｔ１２、ＤＥＳ－Ｔ１５；シロキサンの重合度合いに応じた動粘度５５ｃＳｔ以下のもの）を用いることが考えられる。 Here, as the polydiethylsiloxane employing an ethyl group as an organic group, one having a kinematic viscosity depending on the degree of polymerization of the siloxane can be used. Specifically, it is conceivable to use polydiethylsiloxane (product code DES-T11, DES-T12, DES-T15; kinematic viscosity of 55 cSt or less depending on the degree of polymerization of the siloxane) manufactured by Gelest, USA.
磁性粒子群は、磁性粒子として酸化鉄系の粒子が用いられているが、その他、フェロ磁性を示す粒子、反フェロ磁性を示す粒子、常磁性または超常磁性を示す粒子のうちの１種類以上の粒子からなるもの、より具体的には、例えば、鉄、ニッケル、コバルト、カルボニル鉄、鉄合金、酸化鉄、窒化鉄、炭化鉄、低炭素鋼、希土類、これらの混合物、または、これら１種類以上の合金を材料とするものを用いることもできる。 In the magnetic particle group, iron oxide particles are used as magnetic particles, but in addition, one or more of the following particles are used: particles exhibiting ferromagnetism, particles exhibiting antiferromagnetism, particles exhibiting paramagnetism or superparamagnetism. Particles, more specifically, for example, iron, nickel, cobalt, carbonyl iron, iron alloys, iron oxide, iron nitride, iron carbide, low carbon steel, rare earths, mixtures thereof, or one or more of these. It is also possible to use a material made of an alloy of.
界面活性剤は、石油系の界面活性剤であり、少なくとも一つの極性基を有する炭化水素系のものとして、例えば、直鎖型炭化水素系や芳香族炭化水素系などが挙げられる。
本願出願人は、シリコーンオイルおよび界面活性剤の極性に着目したうえで、本発明の磁性流体に適用可能な界面活性剤を選定した。具体的には、シリコーンオイルのポリシロキサンがＳｉ－Ｏの結合に含まれる酸素により電子の偏りによる“極性”を有する一方、一般的なアルキル基やフェニル基には、分子中に酸素原子を含有していないなどといった要因から大きな電子の偏りがなく、”極性”を有していない（つまり非極性である）。そのため、このアルキル基やフェニル基との親和性を高める観点で、同じく非極性である石油系や脂肪酸などの界面活性剤の中から上記の界面活性剤を選定している。
The surfactant is a petroleum-based surfactant, and examples of hydrocarbon-based surfactants having at least one polar group include linear hydrocarbon-based and aromatic hydrocarbon-based.
The applicant of the present application focused on the polarity of the silicone oil and the surfactant and selected a surfactant that can be applied to the magnetic fluid of the present invention. Specifically, while the polysiloxane of silicone oil has "polarity" due to electron bias due to the oxygen contained in the Si-O bond, general alkyl groups and phenyl groups contain oxygen atoms in the molecule. There is no large electron bias due to factors such as non-polarity, and it does not have "polarity" (in other words, it is non-polar). Therefore, from the viewpoint of increasing the affinity with the alkyl group and phenyl group, the above-mentioned surfactant is selected from petroleum-based surfactants, fatty acids, and other surfactants that are also nonpolar.
こうして、シリコーンオイルと石油系の界面活性剤で覆われた磁性粒子との親和性を高めることにより、シリコーンオイル中で磁性粒子を均一に分散させて偏りにくくすることができる。 In this way, by increasing the affinity between the silicone oil and the magnetic particles covered with a petroleum-based surfactant, it is possible to uniformly disperse the magnetic particles in the silicone oil and make them less likely to be biased.
以上、本発明の実施の形態について説明したが、本発明は、上記実施形態に何ら限定されることはなく、本発明の技術的範囲に属する限り種々の形態をとり得ることはいうまでもない。
（２）評価
本願出願人は、本発明の磁性流体を評価すべく、比較対象となる磁性流体を用意し、それの粘度を試験している。
Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and can take various forms as long as they fall within the technical scope of the present invention. .
(2) Evaluation In order to evaluate the magnetic fluid of the present invention, the applicant has prepared a magnetic fluid for comparison and tested its viscosity.
まず、比較対象となる磁性流体として、ポリジメチルシロキサンからなる４種類（動粘度が異なる）のシリコーンオイルを用意し、それぞれに酸化鉄からなる標準的な粒径分布（平均粒径１０ｎｍ）の磁性粒子からなる磁性粒子群を分散させたものを作製した。磁性粒子は、それぞれに、特許文献１に記載された少なくとも一つの極性基を有する炭化水素系の第１界面活性剤と、シリコーンオイル担体に可溶性を有するシリコーン系の第２界面活性剤とをコーティングして用いている。
First, we prepared four types of silicone oil (with different kinematic viscosities) made of polydimethylsiloxane as magnetic fluids to be compared, and each of them had a magnetic fluid with a standard particle size distribution (
磁性流体としては、単位体積（立方センチ）あたりに分散された磁性粒子の粒子量（重量ｇまたは単位体積）に応じた飽和磁化が１０ｍＴ（ミリテスラ）以上となる量だけシリコーンオイル中に磁性粒子群を分散させている。 As the magnetic fluid, magnetic particles are mixed in silicone oil in an amount such that the saturation magnetization is 10 mT (millitesla) or more according to the amount of magnetic particles dispersed per unit volume (cubic centimeter) (weight g or unit volume). are dispersed.
本試験に際しては、シリコーンオイルの種類ごとに、磁性粒子群の分散量を１０ｍＴ以上で異ならせた複数の磁性流体を作製したうえで、各シリコーンオイルの粘度を試験した。粘度は、ＪＩＳ Ｚ８８０３「円錐平板形回転粘度計による粘度測定方法」に従い、Ｅ型粘度計を使用して測定した。Ｅ型粘度計としては、東機産業株式会社製のＲ８５形粘度計を用いた。 In this test, a plurality of magnetic fluids were prepared for each type of silicone oil in which the amount of dispersed magnetic particles was varied by 10 mT or more, and then the viscosity of each silicone oil was tested. The viscosity was measured using an E-type viscometer according to JIS Z8803 "Viscosity measurement method using a cone-plate rotational viscometer." As the E-type viscometer, an R85 type viscometer manufactured by Toki Sangyo Co., Ltd. was used.
この試験における、シリコーンオイルそれぞれの磁性粒子群の分子量と粘度との関係をみると、図１に示すように、磁性粒子群の粒子量１７ｍＴを超えた領域では、いずれのシリコーンオイルを用いた磁性流体においても、粘度が１０００ｍＰａ．ｓを超えていることが確認された。 Looking at the relationship between the molecular weight and viscosity of the magnetic particle group of each silicone oil in this test, as shown in Figure 1, in the region where the particle amount of the magnetic particle group exceeds 17 mT, the magnetic Even in fluids, the viscosity is 1000mPa. It was confirmed that it exceeds s.
これに対し、本発明の磁性流体として、米国Ｇｅｌｅｓｔ社製のポリジエチルシロキサンからなる下記３種類のシリコーンオイルを用意し、それぞれに酸化鉄からなる標準的な粒径分布（平均粒径１０ｎｍ）の磁性粒子からなる磁性粒子群を分散させることにより磁性流体を作製した。磁性粒子は、それぞれ炭化水素系の一般的な界面活性剤をコーティングして用いている。
※シリコーンオイルの種類
・製品コードＤＥＳ－Ｔ１１：動粘度６．３～１３．２ｃＳｔ
・製品コードＤＥＳ－Ｔ１２：動粘度１３．５～２２ｃＳｔ
・製品コードＤＥＳ－Ｔ１５：動粘度３６～５５ｃＳｔ
磁性流体としては、単位体積（立方センチ）あたりに分散された磁性粒子の粒子量（重量ｇまたは単位体積）に応じた飽和磁化が１５ｍＴ（ミリテスラ）以上となる量だけシリコーンオイル中に磁性粒子群を分散させている。なお、このように、シリコーンオイル中に、石油系の界面活性剤で覆われた磁性粒子を分散させた磁性流体では、１種類の界面活性剤のみであっても、上記比較対象となる磁性流体と同様に、磁性粒子が均一に分散され偏りにくくなっていることが確認されている。これは、界面活性剤とシリコーンオイルとの親和性に起因するものといえる。
On the other hand, as the magnetic fluid of the present invention, we prepared the following three types of silicone oils made of polydiethylsiloxane manufactured by Gelest, USA, and each of them had a standard particle size distribution (
*Silicone oil type/product code DES-T11: Kinematic viscosity 6.3 to 13.2 cSt
・Product code DES-T12: Kinematic viscosity 13.5-22cSt
・Product code DES-T15: Kinematic viscosity 36-55cSt
The magnetic fluid contains magnetic particles in silicone oil in an amount such that the saturation magnetization is 15 mT (millitesla) or more according to the amount of magnetic particles dispersed per unit volume (cubic centimeter) (weight g or unit volume). are dispersed. In addition, in a magnetic fluid in which magnetic particles covered with a petroleum-based surfactant are dispersed in silicone oil, even if only one type of surfactant is used, the magnetic fluid used for comparison above is Similarly, it has been confirmed that the magnetic particles are uniformly dispersed and are less likely to be biased. This can be said to be due to the affinity between the surfactant and silicone oil.
本試験に際しては、シリコーンオイルの種類ごとに、磁性粒子群の分散量を１５ｍＴ以上で異ならせた複数の磁性流体を作製したうえで、各シリコーンオイルの粘度を試験した。粘度は、上記と同様、Ｅ型粘度計を使用して測定した。 In this test, a plurality of magnetic fluids were prepared for each type of silicone oil in which the amount of dispersed magnetic particles was varied by 15 mT or more, and then the viscosity of each silicone oil was tested. The viscosity was measured using an E-type viscometer in the same manner as above.
この試験による、磁性粒子群の分散量と粘度との関係は、下記表１のとおりであり、この結果をみると、図２に示すように、磁性粒子群の分散量１５ｍＴ～５０ｍＴに対する粘度は、いずれのシリコーンオイルを用いた磁性流体においても、１０００ｍＰａ．ｓを超えない範囲となることが確認された。このように、比較対象の磁性流体よりも磁性粒子群の分散量に応じた粘度の上昇が抑えられていることがわかる。 The relationship between the amount of dispersion of the magnetic particle group and the viscosity according to this test is shown in Table 1 below. Looking at the results, as shown in Figure 2, the viscosity for the amount of dispersion of the magnetic particle group of 15 mT to 50 mT is , 1000 mPa. It was confirmed that the range does not exceed s. In this way, it can be seen that the increase in viscosity depending on the amount of dispersion of the magnetic particle group is suppressed more than in the comparative magnetic fluid.
このように、磁性粒子群の分散量に応じた粘度の上昇が抑えられていることにより、粘度に応じてシリコーンオイル中で磁性流体が受ける抵抗も抑えられるため、磁場の変化に対する応答が安定するなど磁場環境下の分散性が高いものとなっている。
（３）作用，効果
上記磁性流体であれば、１種類の界面活性剤のみであっても磁性粒子のシリコーンオイル中での分散性を持たせることができ、２種類の界面活性剤を使用する場合と比べて、磁性粒子の数が同数であれば、磁性粒子の数に応じて界面活性剤の占める領域が大きくなりにくく、磁性流体としての粘度も高くなりにくい。こうして、シリコーンオイルに分散させる磁性粒子を増やしやすく、使用環境に求められる粘度と応答性を両立することが可能となるため、使用環境の選択肢を増やすことができる。
In this way, by suppressing the increase in viscosity depending on the amount of dispersion of magnetic particles, the resistance that the magnetic fluid receives in silicone oil is also suppressed depending on the viscosity, so the response to changes in the magnetic field is stabilized. It has a high dispersibility in a magnetic field environment.
(3) Actions and Effects With the above magnetic fluid, it is possible to make the magnetic particles dispersible in silicone oil even if only one type of surfactant is used, and two types of surfactants are used. If the number of magnetic particles is the same, the area occupied by the surfactant is less likely to increase in proportion to the number of magnetic particles, and the viscosity of the magnetic fluid is less likely to increase. In this way, it is easy to increase the number of magnetic particles dispersed in the silicone oil, and it is possible to achieve both the viscosity and responsiveness required for the usage environment, so it is possible to increase the options for the usage environment.
例えば、応答性よりも分散性など別の性能が優先される使用環境が想定される場合には、磁性粒子に分散性を向上させるべく別の界面活性剤を付与したり、シリコーンオイルに酸化防止剤を含有させたりすることにより、その使用環境での使用が実現可能となる。 For example, if a usage environment is envisaged where other performance such as dispersibility takes precedence over responsiveness, it may be necessary to add another surfactant to magnetic particles to improve dispersibility or to prevent oxidation from silicone oil. By incorporating agents, it becomes possible to use the product in the environment in which it is used.
特に、上記磁性流体では、磁性粒子群の分散量を１５ｍＴ以上に増やしたとしても、磁性流体としての粘度を１０００ｍＰａ．ｓを超えない範囲とすることができる。これにより、２種類の界面活性剤を使用する場合と比べて、より多くの磁性粒子群を分散させた分散性の高い磁性粒子を実現することができる。 In particular, in the above magnetic fluid, even if the amount of dispersion of the magnetic particle group is increased to 15 mT or more, the viscosity of the magnetic fluid is 1000 mPa. It can be set within a range not exceeding s. This makes it possible to achieve highly dispersible magnetic particles in which more magnetic particle groups are dispersed than when two types of surfactants are used.
Claims (1)
前記シリコーンオイル中に分散された複数の磁性粒子からなる磁性粒子群と、
前記磁性粒子それぞれの表面を覆う石油系の界面活性剤と、からなり、
前記シリコーンオイルには、ポリシロキサンの有機基として、直鎖型・分岐型のアルキル基であるエチル基、プロピル基、ブチル基が採用されており、
前記磁性粒子群は、単位体積あたりに分散された磁性粒子の粒子量に応じた飽和磁化が１０ｍＴ以上となる量だけ前記シリコーンオイル中に分散されており、
さらに、１種類の界面活性剤のみが用いられている、
磁性流体。 silicone oil made of polysiloxane having an organic group side chain in an inorganic siloxane bond;
a magnetic particle group consisting of a plurality of magnetic particles dispersed in the silicone oil;
a petroleum-based surfactant that covers the surface of each of the magnetic particles,
The silicone oil employs linear/branched alkyl groups such as ethyl, propyl, and butyl groups as the organic groups of polysiloxane .
The magnetic particle group is dispersed in the silicone oil in an amount such that the saturation magnetization according to the amount of magnetic particles dispersed per unit volume is 10 mT or more,
Furthermore, only one type of surfactant is used,
magnetic fluid.
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| 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 |
| JP2006114751A (en) | 2004-10-15 | 2006-04-27 | Toda Kogyo Corp | Magnetic fluid and its manufacturing method |
| JP2014095031A (en) | 2012-11-09 | 2014-05-22 | Cosmo Oil Lubricants Co Ltd | Magnetic viscous fluid composition |
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| JPS63175401A (en) * | 1987-01-14 | 1988-07-19 | Nippon Seiko Kk | Low temperature magnetic fluid |
| JP3768564B2 (en) * | 1995-07-03 | 2006-04-19 | 豊久 藤田 | Silicone oil-based magnetic fluid and process for producing the same |
| US5851416A (en) * | 1997-02-12 | 1998-12-22 | Ferrofluidics Corporation | Stable polysiloxane ferrofluid compositions and method of making same |
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| 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 |
| JP2006114751A (en) | 2004-10-15 | 2006-04-27 | Toda Kogyo Corp | Magnetic fluid and its manufacturing method |
| JP2014095031A (en) | 2012-11-09 | 2014-05-22 | Cosmo Oil Lubricants Co Ltd | Magnetic viscous fluid composition |
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