JP2018041807A - Temperature sensitive magnetic fluid and magnetic fluid driving device using the same - Google Patents
Temperature sensitive magnetic fluid and magnetic fluid driving device using the same Download PDFInfo
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Abstract
Description
本発明は、感温性磁性流体、及び該感温性磁性流体を用いた磁性流体駆動装置に係り、更に詳細には、磁場勾配を形成し温度勾配を与えることで流動する感温性磁性流体、及びそれを用いた磁性流体駆動装置に関する。 The present invention relates to a temperature-sensitive magnetic fluid and a magnetic fluid driving apparatus using the temperature-sensitive magnetic fluid, and more specifically, a temperature-sensitive magnetic fluid that flows by forming a magnetic field gradient and applying a temperature gradient. And a magnetic fluid driving apparatus using the same.
従来、ヒートパイプ等の自己循環型の熱輸送装置が電子機器の冷却に用いられている。
しかし、電子機器の小型化・高性能化により、電子機器に搭載される半導体素子が高密度化され、発熱密度が高くなっているため、高効率の自己循環型の熱輸送システムが要望される。
Conventionally, self-circulating heat transport devices such as heat pipes are used for cooling electronic devices.
However, due to the downsizing and high performance of electronic equipment, the density of semiconductor elements mounted on electronic equipment has increased and the heat generation density has increased, so a highly efficient self-circulating heat transport system is required. .
特許文献１の特開２０１４−１３４３３５号公報には、感温性磁性流体を循環流路中に封入し、該循環流路内の磁性流体を加熱すると共に磁場を印加して、上記感温性磁性流体を循環させることで、熱を輸送できる磁性流体駆動装置が開示されている。
Japanese Patent Application Laid-Open No. 2014-134335 of
上記感温性磁性流体は、キュリー温度の低い磁性微粒子を分散媒中に安定分散させた流体であり、常温域において磁場と熱に感応するものであって、外部から上記感温性磁性流体に磁場および熱を入力することで、磁化の空間的な非平衡状態に起因して流体が自己駆動するものである。 The temperature-sensitive magnetic fluid is a fluid in which magnetic fine particles having a low Curie temperature are stably dispersed in a dispersion medium, and is sensitive to a magnetic field and heat in a room temperature range. By inputting a magnetic field and heat, the fluid is self-driven due to a spatial non-equilibrium state of magnetization.
したがって、上記感温性磁性流体は、ポンプなどの機械的要素を用いずに電力フリーで熱輸送することができる。 Therefore, the temperature-sensitive magnetic fluid can be transported by heat without using a mechanical element such as a pump.
さらに、上記磁性流体駆動装置は、磁気体積力を利用するものであって、その駆動に重力を必要としないため、加熱により気化した熱媒体が凝縮し流下することで循環するヒートパイプでは困難であった水平重力方向や微小重力環境下においても熱輸送が可能である。 Furthermore, the magnetic fluid driving device uses a magnetic body force and does not require gravity to drive the magnetic fluid driving device. Therefore, it is difficult for a heat pipe that circulates as the heat medium vaporized by heating condenses and flows down. Heat transport is possible even in the horizontal gravity direction and microgravity environment.
上記磁性流体駆動装置に用いられる感温性磁性流体は、高温に曝されるものであり、万一漏れが生じると火災の危険性があるため消防法上の非危険物であることが望ましい。 The temperature-sensitive magnetic fluid used in the magnetic fluid driving device is exposed to a high temperature, and if it leaks, there is a risk of fire.
特許文献２の特公平７−３８３２８号公報には、水ベースの感温性磁性流体が開示されている。上記感温性磁性流体は、温度の変化に対する磁化の変化が鋭敏な特定組成の強磁性金属酸化物微粒子を用いたものであり、上記強磁性金属酸化物微粒子の表面を界面活性物質で被覆して水中に分散させたものである。
Japanese Patent Publication No. 7-38328 of
しかしながら、特許文献２の感温性磁性流体は、強磁性金属酸化物微粒子の表面にオレイン酸を吸着させた後に、ドデシルベンゼンスルホン酸ナトリウムによって上記強磁性金属酸化物微粒子を水中に分散するものであり、感温性磁性流体の粘度が高いため、上記粘度に対する充分な駆動力を得ることが困難で高効率な熱輸送が困難である。
However, the temperature-sensitive magnetic fluid of
すなわち、特許文献２の感温性磁性流体における強磁性金属酸化物微粒子は、表面に形成される１層目のオレイン酸の吸着層の上に２層目のドデシルベンゼンスルホン酸ナトリウムが吸着することにより、吸着層自体が厚くなることに加えて、過剰のドデシルベンゼンスルホン酸ナトリウムによりさらに粘度が高くなるため、自己駆動性の向上が困難である。
That is, the ferromagnetic metal oxide fine particles in the temperature-sensitive magnetic fluid of
そして、感温性磁性流体中の強磁性金属酸化物微粒子濃度を低くすることで、感温性磁性流体の粘度を下げることは可能であるが、感温性磁性流体の飽和磁化が低下して駆動力も低下するため、自己駆動性を向上させることはできない。
また、上記２層目のドデシルベンゼンスルホン酸ナトリウムは、単なる物理吸着によって、オレイン酸を介して感温性磁性粒子に付着したものであるため、強磁場下での分散安定性が充分でない。
It is possible to reduce the viscosity of the temperature-sensitive magnetic fluid by reducing the concentration of the ferromagnetic metal oxide fine particles in the temperature-sensitive magnetic fluid, but the saturation magnetization of the temperature-sensitive magnetic fluid decreases. Since driving force also decreases, self-driving cannot be improved.
In addition, since the second layer of sodium dodecylbenzenesulfonate is attached to the temperature-sensitive magnetic particles via oleic acid by simple physical adsorption, the dispersion stability under a strong magnetic field is not sufficient.
本発明は、このような従来技術の有する課題に鑑みてなされたものであり、その目的とするところは、粘度が低く高い自己駆動性を有する水系の感温性磁性流体、及び、それを用いた磁性流体駆動装置を提供することにある。 The present invention has been made in view of such problems of the prior art, and an object of the present invention is to use an aqueous temperature-sensitive magnetic fluid having a low viscosity and high self-driving properties, and using the same. An object of the present invention is to provide a magnetic fluid driving apparatus.
本発明者は、上記目的を達成すべく鋭意検討を重ねた結果、強磁性金属酸化物微粒子の表面にメルカプト基を含有する吸着剤が直接付着した感温性磁性粒子を水系分散媒中に分散することにより、上記目的が達成できることを見出し、本発明を完成するに至った。 As a result of intensive studies to achieve the above object, the present inventor dispersed temperature-sensitive magnetic particles having adsorbents containing mercapto groups directly on the surface of the ferromagnetic metal oxide fine particles in an aqueous dispersion medium. As a result, the inventors have found that the above object can be achieved and have completed the present invention.
上記課題は、本発明の下記（１）〜（６）の感温性磁性流体によって解決される。
（１）感温性磁性粒子と水系分散媒とを、含有する感温性磁性流体であって、
上記感温性磁性粒子が、強磁性金属酸化物微粒子の表面にメルカプト酢酸、メルカプトプロピオン酸、メルカプトエタノールから選ばれる少なくとも一つのメルカプト基を含有する吸着剤が直接付着したものであることを特徴とする感温性磁性流体。
（２）粘度（２５℃）が、５０（ｍＰａ・ｓ）以下であることを特徴とする（１）記載の感温性磁性流体。
（３）飽和磁化（２５℃）が １０〜１００（ｍＴ）であることを特徴とする（１）又は（２）に記載の感温性磁性流体。
（４）上記感温性磁性粒子の含有量が、１０質量％以上６０質量％以下であることを特徴とする（１）〜（３）のいずれか１つの項に記載の感温性磁性流体。
（５）ｐＨが８．０〜１４．０であることを特徴とする（１）〜（４）のいずれか１つの項に記載の感温性磁性流体。
（６）上記強磁性金属酸化物微粒子が、マンガン亜鉛フェライト粒子であることを特徴とする（１）〜（５）のいずれか１つの項に記載の感温性磁性流体。
The above problems are solved by the following thermosensitive magnetic fluids (1) to (6) of the present invention.
(1) A temperature-sensitive magnetic fluid containing a temperature-sensitive magnetic particle and an aqueous dispersion medium,
The temperature-sensitive magnetic particles are characterized in that an adsorbent containing at least one mercapto group selected from mercaptoacetic acid, mercaptopropionic acid, and mercaptoethanol is directly attached to the surface of the ferromagnetic metal oxide fine particles. A temperature-sensitive magnetic fluid.
(2) The temperature-sensitive magnetic fluid according to (1), wherein the viscosity (25 ° C.) is 50 (mPa · s) or less.
(3) The temperature-sensitive magnetic fluid according to (1) or (2), wherein the saturation magnetization (25 ° C.) is 10 to 100 (mT).
(4) The temperature-sensitive magnetic fluid according to any one of (1) to (3), wherein the content of the temperature-sensitive magnetic particles is 10% by mass or more and 60% by mass or less. .
(5) The temperature-sensitive magnetic fluid according to any one of (1) to (4), wherein the pH is 8.0 to 14.0.
(6) The temperature-sensitive magnetic fluid according to any one of (1) to (5), wherein the ferromagnetic metal oxide fine particles are manganese zinc ferrite particles.
また、上記課題は、本発明の下記（７）の磁性流体駆動装置によって解決される。
（７）感温性磁性流体を循環させる循環流路と、該循環流路内の感温性磁性流体に磁場を印加する磁場印加部と、該磁場印加部の一部を加熱して磁場印加部の感温性磁性流体に温度勾配を与える加熱部とを備える磁性流体駆動装置であって、
上記感温性磁性流体が、上記（１）〜（６）のいずれか１つの項に記載の感温性磁性流体であることを特徴とする磁性流体駆動装置。
Further, the above-described problem is solved by the magnetic fluid driving device of the following (7) of the present invention.
(7) A circulation channel for circulating the temperature-sensitive magnetic fluid, a magnetic field application unit for applying a magnetic field to the temperature-sensitive magnetic fluid in the circulation channel, and applying a magnetic field by heating a part of the magnetic field application unit A magnetic fluid driving device comprising a heating unit that gives a temperature gradient to a part of the temperature-sensitive magnetic fluid,
The temperature-sensitive magnetic fluid is the temperature-sensitive magnetic fluid according to any one of (1) to (6) above.
本発明によれば、強磁性金属酸化物微粒子の表面にメルカプト基を含有する吸着剤を直接付着させた感温性磁性粒子を水系分散媒中に分散することとしたため、自己駆動性の高い水系の感温性磁性流体を提供することができる。 According to the present invention, the temperature-sensitive magnetic particles in which the adsorbent containing a mercapto group is directly attached to the surface of the ferromagnetic metal oxide fine particles are dispersed in the aqueous dispersion medium. Temperature-sensitive magnetic fluid can be provided.
本発明の感温性磁性流体について詳細に説明する。
上記感温性磁性流体は、感温性磁性粒子を水系分散媒に分散させたものであり、必要に応じてｐＨ調整剤等の他の添加剤を含有して成る。
そして、上記感温性磁性粒子が、強磁性金属酸化物微粒子の表面にメルカプト基を含有する吸着剤が直接付着したものである。
The temperature-sensitive magnetic fluid of the present invention will be described in detail.
The temperature-sensitive magnetic fluid is obtained by dispersing temperature-sensitive magnetic particles in an aqueous dispersion medium, and contains other additives such as a pH adjuster as necessary.
The temperature-sensitive magnetic particles are those in which an adsorbent containing a mercapto group is directly attached to the surface of the ferromagnetic metal oxide fine particles.
＜吸着剤＞
上記吸着剤は、強磁性金属酸化物微粒子に付着して強磁性金属酸化物微粒子の表面を被覆し、強磁場の中においても上記強磁性金属酸化物微粒子を水系分散媒中に安定して分散させるものである。
<Adsorbent>
The adsorbent adheres to the ferromagnetic metal oxide fine particles to cover the surface of the ferromagnetic metal oxide fine particles, and the ferromagnetic metal oxide fine particles are stably dispersed in the aqueous dispersion medium even in a strong magnetic field. It is something to be made.
上記メルカプト基を含有する吸着剤としては、メルカプトカルボン酸類やメルカプトアルコール類を用いることができる。 As the adsorbent containing the mercapto group, mercaptocarboxylic acids and mercapto alcohols can be used.
上記メルカプトカルボン酸類としては、例えば、メルカプト酢酸、メルカプトプロピオン酸等を挙げることでき、また、上記メルカプトアルコール類としては、メルカプトエタノールを挙げることができる。
これらは、１種又は２種以上混合して用いることができ、中でも、メルカプトプロピオン酸は強磁性金属酸化物微粒子に付着し易く、好ましく使用できる。
Examples of the mercaptocarboxylic acids include mercaptoacetic acid and mercaptopropionic acid, and examples of the mercaptoalcohols include mercaptoethanol.
These can be used alone or in combination of two or more. Among them, mercaptopropionic acid can be preferably used because it easily adheres to the ferromagnetic metal oxide fine particles.
＜強磁性金属酸化物微粒子＞
上記強磁性金属酸化物微粒子としては、強磁性金属酸化物微粒子群全体として超常磁性を示すフェライト粒子を使用することができ、粒径が３ｎｍ〜５０ｎｍであるものを使用できる。
上記超常磁性とは、磁場をかけることで粒子の磁化が磁場方向に揃い、零磁場では熱擾乱によって磁化が粒子内で固定されずランダムに回転し、全体として磁化がゼロになる性質をいう。
<Ferromagnetic metal oxide fine particles>
As the ferromagnetic metal oxide fine particles, ferrite particles exhibiting superparamagnetism as a whole of the ferromagnetic metal oxide fine particle group can be used, and those having a particle diameter of 3 nm to 50 nm can be used.
Superparamagnetism refers to the property that when a magnetic field is applied, the magnetization of the particles is aligned in the direction of the magnetic field, and in a zero magnetic field, the magnetization is not fixed within the particle but rotated randomly due to thermal disturbance, and the magnetization becomes zero as a whole.
上記フェライト粒子としては、マグネタイト（ＦｅＯ・Ｆｅ２Ｏ３）粒子、マンガン亜鉛フェライト（ＭｎｘＺｎ１−ｘ・Ｆｅ２Ｏ４）粒子、（ＭｎＯ）ｘ・（ＣａＯ）ｙ・（ＺｎＯ）ｚ・Ｆｅ２Ｏ３粒子等を挙げることができ、中でも、マンガン亜鉛フェライト粒子は磁化が高く好ましく使用できる。 Examples of the ferrite particles include magnetite (FeO · Fe 2 O 3 ) particles, manganese zinc ferrite (Mn x Zn 1-x · Fe 2 O 4 ) particles, (MnO) x · (CaO) y · (ZnO) z ·. Examples thereof include Fe 2 O 3 particles. Among these, manganese zinc ferrite particles have high magnetization and can be preferably used.
特に、下記組成式（１）で表されるマンガン亜鉛フェライト粒子は、０℃〜１００℃の常温域において、温度上昇に伴う磁化の減少が大きく、高い駆動力が得られるものである。 In particular, the manganese zinc ferrite particles represented by the following composition formula (1) have a large decrease in magnetization accompanying a temperature rise in a normal temperature range of 0 ° C. to 100 ° C., and a high driving force can be obtained.
（ＭｎＯ）Ｘ・（ＺｎＯ）Ｙ・（Ｆｅ２Ｏ３）Ｚ・・・組成式（１）
但し、組成式（１）中、Ｘ、Ｙ、及びＺは、０．２３≦Ｘ≦０．３５、０．１２≦Ｙ≦０．２４、０．４８≦Ｚ≦０．５８、Ｘ＋Ｙ＋Ｚ＝１を満たす。
(MnO) X · (ZnO) Y · (Fe 2 O 3) Z ··· composition formula (1)
However, in the composition formula (1), X, Y, and Z are 0.23 ≦ X ≦ 0.35, 0.12 ≦ Y ≦ 0.24, 0.48 ≦ Z ≦ 0.58, and X + Y + Z = 1. Meet.
上記強磁性金属酸化物微粒子は、液相法により作製することができる。具体的には、フェライト粒子を構成する金属の金属塩水溶液にアルカリを添加して中和し、共沈物を生成させ、該共沈物を加熱・反応させることで作製できる。 The ferromagnetic metal oxide fine particles can be produced by a liquid phase method. Specifically, it can be prepared by adding an alkali to the metal salt aqueous solution of the metal constituting the ferrite particles to neutralize it, generating a coprecipitate, and heating and reacting the coprecipitate.
＜感温性磁性粒子＞
感温性磁性粒子は、上記強磁性金属酸化物微粒子の水性懸濁液と上記メルカプト基を含有する吸着剤とを混合し、強磁性金属酸化物微粒子の表面にメルカプト基を含有する吸着剤を直接付着させることで作製できる。
<Temperature-sensitive magnetic particles>
The temperature-sensitive magnetic particles are prepared by mixing an aqueous suspension of the ferromagnetic metal oxide fine particles and the adsorbent containing the mercapto group, and adding an adsorbent containing a mercapto group on the surface of the ferromagnetic metal oxide fine particles. It can be produced by direct attachment.
上記感温性磁性粒子は、１層の吸着剤により水系分散媒中に安定して分散するため、吸着層を薄くできる上に、従来過剰に使用されていた２層目の活性剤による感温性磁性流体の増粘を抑制でき、感温性磁性流体中の感温性磁性粒子濃度を高くすることができるため、自己駆動性が向上する。 Since the temperature-sensitive magnetic particles are stably dispersed in the aqueous dispersion medium by one layer of the adsorbent, the adsorption layer can be made thin and the temperature sensitivity by the second layer activator that has been used excessively in the past. Since the viscosity of the magnetic fluid can be suppressed and the concentration of the temperature-sensitive magnetic particles in the temperature-sensitive magnetic fluid can be increased, the self-driving property is improved.
上記メルカプト基を含有する吸着剤の使用量は、使用する吸着剤にもよるが、強磁性金属酸化物微粒子１質量部に対し、１０質量％以上１００質量％以下であることが好ましい。
上記範囲の吸着剤を使用することで安定性を向上させる効果が得られ易い。
なお、上記メルカプトカルボン酸は二量化し易い性質を有し、使用した吸着剤のすべてが感温性磁性粒子の分散安定性に寄与するわけではないため、過剰に使用することが好ましい。
The amount of the adsorbent containing the mercapto group is preferably 10% by mass or more and 100% by mass or less with respect to 1 part by mass of the ferromagnetic metal oxide fine particles, although it depends on the adsorbent used.
By using an adsorbent in the above range, the effect of improving the stability is easily obtained.
The mercaptocarboxylic acid has the property of being easily dimerized, and not all of the adsorbent used contributes to the dispersion stability of the temperature-sensitive magnetic particles, so that it is preferably used in excess.
＜水系分散媒＞
上記水系媒体としては、水、グリコール等の多価アルコール類を使用することができるが、燃性及び粘度の観点から水であることが好ましい。
本発明の感温性磁性流体は、水系分散媒を用いるものであるため、油性の分散媒を用いた感温性磁性流体に比して比熱及び熱伝導率が大きく、顕熱による熱輸送効率が向上する。また、水系分散媒は油系分散媒に比して蒸発潜熱が大きく、潜熱による熱輸送効率も向上する。
<Aqueous dispersion medium>
As the aqueous medium, polyhydric alcohols such as water and glycol can be used, but water is preferable from the viewpoints of flammability and viscosity.
Since the temperature-sensitive magnetic fluid of the present invention uses an aqueous dispersion medium, the specific heat and thermal conductivity are larger than the temperature-sensitive magnetic fluid using an oil-based dispersion medium, and the heat transport efficiency by sensible heat is high. Will improve. Further, the aqueous dispersion medium has a larger latent heat of evaporation than the oil-based dispersion medium, and the heat transport efficiency by the latent heat is improved.
＜ｐＨ調整剤＞
ｐＨ調整剤は、感温性磁性流体のｐＨを調整するものであり、感温性磁性流体のｐＨを８〜１４、好ましくは８〜１３、より好ましくは８〜１２に調整することで、感温性磁性粒子を水系分散媒中に安定して分散させることができる。
<PH adjuster>
The pH adjuster adjusts the pH of the temperature-sensitive magnetic fluid. By adjusting the pH of the temperature-sensitive magnetic fluid to 8 to 14, preferably 8 to 13, more preferably 8 to 12, Warm magnetic particles can be stably dispersed in an aqueous dispersion medium.
上記ｐＨ調整剤としては、例えば、水酸化ナトリウム、水酸化カリウム、水酸化カルシウム等のアルカリ金属や、アルカリ土類金属の水酸化物を挙げることができる。 Examples of the pH adjuster include alkali metals such as sodium hydroxide, potassium hydroxide, and calcium hydroxide, and hydroxides of alkaline earth metals.
＜感温性磁性流体の製造＞
上記感温性磁性流体は、予めｐＨを調整した水系媒体中に上記感温性磁性粒子を加え、分散させることで作製できる。
<Manufacture of temperature-sensitive magnetic fluid>
The temperature-sensitive magnetic fluid can be produced by adding and dispersing the temperature-sensitive magnetic particles in an aqueous medium whose pH has been adjusted in advance.
上記感温性磁性流体中の上記感温性磁性粒子の含有量は、１０質量％以上６０質量％以下であることが好ましい。より好ましくは２５質量％以上６０質量％以下である。
感温性磁性粒子の含有量が上記範囲内であることで、粘度に対する充分な駆動力を得ることができ、自己駆動性を向上させることができる。
The content of the temperature-sensitive magnetic particles in the temperature-sensitive magnetic fluid is preferably 10% by mass or more and 60% by mass or less. More preferably, it is 25 mass% or more and 60 mass% or less.
When the content of the temperature-sensitive magnetic particles is within the above range, a sufficient driving force for the viscosity can be obtained, and the self-driving property can be improved.
また、上記感温性磁性流体の粘度（２５℃）は、３０（ｍＰａ・ｓ）以下であることが好ましく、１５（ｍＰａ・ｓ）以下であることがより好ましい。
感温性磁性流体の粘度は、例えば、東機産業（株）製のＴＰＥ−１００Ｌ形粘度計等を用い、ＪＩＳ Ｚ８８０３に準拠して測定できる。
The viscosity (25 ° C.) of the thermosensitive magnetic fluid is preferably 30 (mPa · s) or less, and more preferably 15 (mPa · s) or less.
The viscosity of the temperature-sensitive magnetic fluid can be measured according to JIS Z8803 using, for example, a TPE-100L viscometer manufactured by Toki Sangyo Co., Ltd.
さらに、上記感温性磁性流体の飽和磁化（２５℃）は、 １０〜１００（ｍＴ）であることが好ましく、２５ｍＴ〜８０ｍＴであることがより好ましい。
感温性磁性流体の飽和磁化は、例えば、理研電子（株）製の磁化測定装置ＢＨＶ−５０等を用いて、感温性磁性流体をセルに充填して磁界を１０ｋＯｅまで掃引した際の履歴曲線から求めることができる。
Furthermore, the saturation magnetization (25 ° C.) of the temperature-sensitive magnetic fluid is preferably 10 to 100 (mT), and more preferably 25 mT to 80 mT.
The saturation magnetization of the temperature-sensitive magnetic fluid is, for example, a history when the cell is filled with the temperature-sensitive magnetic fluid and the magnetic field is swept up to 10 kOe by using a magnetometer BHV-50 manufactured by Riken Denshi Co., Ltd. It can be obtained from a curve.
感温性磁性流体の粘度や飽和磁化が上記範囲内であることで、優れた自己駆動性を得ることができる。 When the viscosity and saturation magnetization of the temperature-sensitive magnetic fluid are within the above ranges, excellent self-driving properties can be obtained.
＜磁性流体駆動装置＞
磁性流体駆動装置は、感温性磁性流体を循環させる循環流路と、感温性磁性流体に磁場を印加する磁場印加部と、該磁場印加部の一部を加熱して上記磁場印加部の感温性磁性流体に温度勾配を与える加熱部とを備える。
上記磁性流体駆動装置は、加熱部での加熱量や、磁場印加部に対する加熱部の位置を調節することで、上記感温性磁性流体の流速や、流れる方向を制御できるものである。
<Magnetic fluid drive device>
The magnetic fluid driving device includes a circulation channel for circulating the temperature-sensitive magnetic fluid, a magnetic field application unit that applies a magnetic field to the temperature-sensitive magnetic fluid, and a part of the magnetic field application unit that heats the magnetic field application unit. And a heating unit that applies a temperature gradient to the temperature-sensitive magnetic fluid.
The magnetic fluid driving device can control the flow rate and the flowing direction of the thermosensitive magnetic fluid by adjusting the heating amount in the heating unit and the position of the heating unit with respect to the magnetic field application unit.
磁性流体駆動装置の加熱部は、図１（ａ）に示すように磁場印加部の一端に設置されている。上記磁場印加部は、図１（ｂ）に示す磁場分布Ｈのように磁場強度の極大点が１個になるように、複数の永久磁石が異極並列に配置されている。 The heating unit of the magnetic fluid driving device is installed at one end of the magnetic field application unit as shown in FIG. In the magnetic field application unit, a plurality of permanent magnets are arranged in parallel with each other so that the maximum point of the magnetic field intensity becomes one as in the magnetic field distribution H shown in FIG.
上記感温性磁性流体は、上記のように超常磁性を示すものであり、磁場印加部の感温性磁性流体は、磁化Ｍを持った流体として振る舞い、温度上昇に伴って磁化Ｍが低下する。
そして、上記磁場印加部の感温性磁性流体には、磁化Ｍと磁場勾配∇Ｈに比例する磁気体積力Ｆ＝Ｍ・∇Ｈが働く。
The temperature-sensitive magnetic fluid exhibits superparamagnetism as described above, and the temperature-sensitive magnetic fluid in the magnetic field application section behaves as a fluid having magnetization M, and the magnetization M decreases as the temperature increases. .
A magnetic volume force F = M · ∇H proportional to the magnetization M and the magnetic field gradient ∇H acts on the temperature-sensitive magnetic fluid of the magnetic field application unit.
加熱前の段階における磁気体積力Ｆは、図１（ｃ）の（ｉ）の曲線のように上記磁場印加部の中心を境界として符号反転する。 The magnetic body force F in the stage before heating is reversed in sign with the center of the magnetic field application unit as a boundary as shown by the curve (i) in FIG.
このとき、感温性磁性流体に作用するトータルの駆動力は、磁気体積力Ｆを示す曲線（ｉ）とｘ軸で囲まれた領域の体積に比例し、正の磁気体積力Ｆ１、Ｆ３及びＦ５の合計と、負の磁気体積力Ｆ２、Ｆ４、及びＦ６の合計とが釣り合う。したがって、感温性磁性流体は流れない。 At this time, the total driving force acting on the thermosensitive magnetic fluid is proportional to the volume surrounded by the curve (i) indicating the magnetic volume force F and the x-axis, and the positive magnetic volume forces F1, F3 and The sum of F5 and the sum of negative magnetic body forces F2, F4, and F6 are balanced. Therefore, the temperature sensitive magnetic fluid does not flow.
そして、上記感温性磁性流体が上記加熱部で加熱されると、温度Ｔの増大に伴い加熱部の磁化Ｍは非加熱部の磁化Ｍ０に対して減少するため、磁気体積力Ｆは、図１（ｃ）の（ｉｉ）の曲線のように変化する。
したがって、加熱部の磁気体積力Ｆ４、Ｆ５、Ｆ６は、非加熱部の磁気体積力Ｆ１、Ｆ２、Ｆ３に比べて小さくなる。
When the temperature-sensitive magnetic fluid is heated by the heating unit, the magnetization M of the heating unit decreases with respect to the magnetization M0 of the non-heating unit as the temperature T increases. It changes like the curve of (ii) of 1 (c).
Therefore, the magnetic volume forces F4, F5, and F6 of the heating unit are smaller than the magnetic volume forces F1, F2, and F3 of the non-heating unit.
このときの加熱部の磁気体積力のうちＦ２は負の向きであるが、Ｆ１と同程度の大きさであることから相殺され、実質的には正方向の磁気体積力Ｆ３が支配的となり、感温性磁性流体はＸ方向に自発的に流れ始める。 Of the magnetic bulk force of the heating unit at this time, F2 is in a negative direction, but is canceled out because it has the same magnitude as F1, and the positive magnetic bulk force F3 becomes substantially dominant, The thermosensitive magnetic fluid starts to flow spontaneously in the X direction.
さらに、感温性磁性流体の温度が上昇して気泡が生じると加熱部における感温性磁性流体の体積が減少して磁化Ｍがさらに減少し、加熱部と非加熱部の磁気体積力の差が増大してＸ方向への駆動力が増大する。 Further, when the temperature of the temperature-sensitive magnetic fluid rises and bubbles are generated, the volume of the temperature-sensitive magnetic fluid in the heating part decreases, the magnetization M further decreases, and the difference in magnetic volume force between the heating part and the non-heating part. Increases and the driving force in the X direction increases.
上記磁性流体駆動装置は、上記磁場印加部に、大きな磁気体積力を生み出す永久磁石磁気回路（磁石と継鉄を合わせたもの）を使用することで、外部電源を必要とせず、加熱のみで駆動できる磁性流体駆動装置とすることができる。 The magnetic fluid drive device uses a permanent magnet magnetic circuit (a combination of a magnet and a yoke) that generates a large magnetic volume force for the magnetic field application unit, so that it does not require an external power supply and is driven only by heating. The magnetic fluid drive device can be made.
そして、電子機器に組み込んで半導体素子等の発熱部を加熱部とすることで、上記半導体素子等を冷却する熱輸送装置として利用することができ、設置方向が不定なモバイル電子機器や無重力環境で用いられる電子機器の熱輸送装置に好適に用いることができる。 And it can be used as a heat transport device that cools the semiconductor element etc. by incorporating the heat generating part such as a semiconductor element into a heating part by incorporating it in an electronic device. It can use suitably for the heat transport apparatus of the used electronic device.
以下、本発明を実施例により詳細に説明するが、本発明は下記実施例に限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example.
［実施例１］
＜強磁性金属酸化物微粒子（フェライト粒子）の作製＞
水酸化ナトリウム ３．５モルを４００ｍｌの水に溶解した水酸化ナトリウム水溶液を８０℃に調整した。
また、硫酸マンガン１水塩 ０．３５モル、硫酸亜鉛７水塩 ０．１６モル、含水硫酸第２鉄 ０．３６モルを、それぞれ水に溶解して、５００ｍｌの金属塩混合水溶液を作製し、６０℃に調整した。
[Example 1]
<Preparation of ferromagnetic metal oxide fine particles (ferrite particles)>
A sodium hydroxide aqueous solution in which 3.5 mol of sodium hydroxide was dissolved in 400 ml of water was adjusted to 80 ° C.
Further, manganese sulfate monohydrate 0.35 mol, zinc sulfate heptahydrate 0.16 mol, hydrous ferric sulfate 0.36 mol were dissolved in water, respectively, to prepare a 500 ml metal salt mixed aqueous solution, Adjusted to 60 ° C.
次に、上記水酸化ナトリウム水溶液を撹拌しながら、上記金属塩混合水溶液を添加して反応させてフェライト粒子を生成させ、ｐＨが１１〜１２となるよう水酸化ナトリウム水溶液で調整し、９０℃以上で１時間熟成させてフェライト粒子の懸濁液を得た。 Next, while stirring the sodium hydroxide aqueous solution, the metal salt mixed aqueous solution is added and reacted to form ferrite particles, adjusted with a sodium hydroxide aqueous solution so that the pH becomes 11 to 12, and 90 ° C. or higher For 1 hour to obtain a suspension of ferrite particles.
１時間熟成後のフェライト懸濁液を塩酸で中和を行いｐＨ７に調整した後、磁気沈降による水洗を繰り返し行い、洗浄液に塩化バリウム水溶液を添加しても白濁しなくなるまで水洗を行い、（ＭｎＯ）０．３・（ＺｎＯ）０．１８・（Ｆｅ２Ｏ３）０．５２フェライト粒子を得た。 The ferrite suspension after aging for 1 hour is neutralized with hydrochloric acid and adjusted to pH 7, and then repeatedly washed with magnetic sedimentation until it does not become cloudy even if an aqueous barium chloride solution is added to the washing solution. ) 0.3 · (ZnO) 0.18 · (Fe 2 O 3 ) 0.52 ferrite particles were obtained.
＜感温性磁性粒子の作製＞
水洗後のフェライト懸濁液に水を加えて１．２ｋｇとし、９５℃に調整した。
また、０．２モルの３‐メルカプトプロピオン酸を３００ｍｌの水に溶解し６０℃に調整した。
<Preparation of temperature-sensitive magnetic particles>
Water was added to the ferrite suspension after washing to 1.2 kg and adjusted to 95 ° C.
Further, 0.2 mol of 3-mercaptopropionic acid was dissolved in 300 ml of water and adjusted to 60 ° C.
次に、上記フェライト粒子の懸濁液を撹拌しながら、３‐メルカプトプロピオン酸溶液を加えて、９５℃で１時間吸着反応を行った。
吸着反応終了後、磁気沈降による水洗を繰り返し行い、過剰の３−メルカプトプロピオン酸を除去し、得られた吸着フェライトを固形分濃度９０％程度にまで濃縮乾燥して乾燥感温性磁性粒子６８ｇを得た。
Next, a 3-mercaptopropionic acid solution was added while stirring the suspension of the ferrite particles, and an adsorption reaction was performed at 95 ° C. for 1 hour.
After completion of the adsorption reaction, washing with water by magnetic precipitation is repeated to remove excess 3-mercaptopropionic acid, and the obtained adsorbed ferrite is concentrated and dried to a solid content concentration of about 90% to obtain 68 g of dried thermosensitive magnetic particles. Obtained.
＜水系感温性磁性流体の作製＞
２４％水酸化ナトリウム水溶液１．６ｇを水６２ｇに溶解し、得られた感温性磁性粒子６５ｇを加えて、３０分間高速撹拌して感温性磁性粒子を分散させたのち、エチレングリコール７．２ｇ、エチレングリコールモノメチルエーテル１８ｇを加えて、更に１０分間高速撹拌する。その後、磁気沈降により精製を繰り返し行い、感温性磁性粒子を２８質量％含む感温性磁性流体８１ｇを得た。
<Production of water-based temperature-sensitive magnetic fluid>
After dissolving 1.6 g of a 24% sodium hydroxide aqueous solution in 62 g of water, adding 65 g of the resulting temperature-sensitive magnetic particles and stirring the mixture at high speed for 30 minutes to disperse the temperature-sensitive magnetic particles, ethylene glycol 7. 2 g and 18 g of ethylene glycol monomethyl ether are added, and the mixture is further stirred at high speed for 10 minutes. Thereafter, purification was repeated by magnetic precipitation to obtain 81 g of a thermosensitive magnetic fluid containing 28 mass% of thermosensitive magnetic particles.
この感温性磁性流体のｐＨは９．０、飽和磁化は２５（ｍＴ）、粘度（２５℃）は１．７（ｍＰａ・ｓ）であった。 The temperature-sensitive magnetic fluid had a pH of 9.0, a saturation magnetization of 25 (mT), and a viscosity (25 ° C.) of 1.7 (mPa · s).
［実施例２］
実施例１と同様に、強磁性金属酸化物微粒子（フェライト粒子）の作製工程、感温性磁性粒子の作製工程を経て得られた乾燥感温性磁性粒子を用いて、以下の水系感温性磁性流体の作製を行った。
[Example 2]
In the same manner as in Example 1, using the dry temperature-sensitive magnetic particles obtained through the production process of the ferromagnetic metal oxide fine particles (ferrite particles) and the production process of the temperature-sensitive magnetic particles, the following water-based temperature sensitivity is obtained. Magnetic fluid was prepared.
２４％水酸化ナトリウム水溶液３．８ｇを水３６ｇに溶解し、得られた感温性磁性粒子６０ｇを加えて、３０分間高速撹拌して感温性磁性粒子を分散させたのち、磁気沈降により精製を繰り返し行い、感温性磁性粒子を４９質量％含む感温性磁性流体８５ｇを得た。 Dissolve 3.8 g of 24% aqueous sodium hydroxide in 36 g of water, add 60 g of the resulting thermosensitive magnetic particles, disperse the thermosensitive magnetic particles by stirring at high speed for 30 minutes, and then purify by magnetic precipitation. Was repeated to obtain 85 g of a thermosensitive magnetic fluid containing 49 mass% of thermosensitive magnetic particles.
この感温性磁性流体のｐＨは８．９、飽和磁化は５５（ｍＴ）、粘度（２５℃）は５．２（ｍＰａ・ｓ）であった。 The temperature-sensitive magnetic fluid had a pH of 8.9, a saturation magnetization of 55 (mT), and a viscosity (25 ° C.) of 5.2 (mPa · s).
［比較例１］
水酸化ナトリウム ３．５モルを４００ｍｌの水に溶解した水酸化ナトリウム水溶液を８０℃に調整した。
また、硫酸マンガン１水塩 ０．３５モル、硫酸亜鉛７水塩 ０．１６モル、含水硫酸第２鉄 ０．３６モルを、それぞれ水に溶解して、５００ｍｌの金属塩混合水溶液を作製し、６０℃に調整した。
[Comparative Example 1]
A sodium hydroxide aqueous solution in which 3.5 mol of sodium hydroxide was dissolved in 400 ml of water was adjusted to 80 ° C.
Further, manganese sulfate monohydrate 0.35 mol, zinc sulfate heptahydrate 0.16 mol, hydrous ferric sulfate 0.36 mol were dissolved in water, respectively, to prepare a 500 ml metal salt mixed aqueous solution, Adjusted to 60 ° C.
次に、上記水酸化ナトリウム水溶液を撹拌しながら、上記金属塩混合水溶液を添加して反応させてフェライト粒子を生成させ、ｐＨが１１〜１２となるよう水酸化ナトリウム水溶液で調整し、９０℃以上で１時間熟成させてフェライト粒子の懸濁液を得た。 Next, while stirring the sodium hydroxide aqueous solution, the metal salt mixed aqueous solution is added and reacted to form ferrite particles, adjusted with a sodium hydroxide aqueous solution so that the pH becomes 11 to 12, and 90 ° C. or higher For 1 hour to obtain a suspension of ferrite particles.
１時間熟成後８０℃まで冷却して０．１３モルのオレイン酸ナトリウムを加えて撹拌溶解させ、８０℃で３０分間撹拌してオレイン酸ナトリウムを吸着させた後、加熱を止め、塩酸で中和を行いｐＨ６．５〜７に調整して、オレイン酸吸着フェライトを凝集させて、（ＭｎＯ）０．３１・（ＺｎＯ）０．１９・（Ｆｅ２Ｏ３）０．５０フェライト粒子を得た。 After aging for 1 hour, cool to 80 ° C, add 0.13 mol sodium oleate and dissolve with stirring, stir at 80 ° C for 30 minutes to adsorb sodium oleate, then stop heating and neutralize with hydrochloric acid The pH was adjusted to 6.5-7, and the oleic acid adsorbed ferrite was aggregated to obtain (MnO) 0.31 · (ZnO) 0.19 · (Fe 2 O 3 ) 0.50 ferrite particles.
得られたオレイン酸吸着フェライトは、ろ布に入れて水洗を繰り返し、洗浄液に塩化バリウム水溶液を添加しても白濁しなくなるまで水洗を行なった後、遠心脱水機で脱水を行い、固形分濃度７０％の含水感温性磁性粒子１０５ｇを得た。 The obtained oleic acid-adsorbed ferrite is repeatedly put in a filter cloth and washed with water until it does not become cloudy even when an aqueous barium chloride solution is added to the washing solution, followed by dehydration with a centrifugal dehydrator and a solid content of 70 % Water-containing temperature-sensitive magnetic particles 105 g were obtained.
＜水系感温性磁性流体の作製＞
水８．１ｇ、５０％ドデシルベンゼンスルホン酸ナトリウム１０．６ｇ、エチレングリコール４．８ｇ、エチレングリコールモノメチルエーテル４．８ｇを均一撹拌し、得られた含水感温性磁性粒子４７ｇ加えて、１時間高速撹拌して感温性磁性粒子を分散させたのち、更に水３０ｇを加えて３０分間高速撹拌する。その後、磁気沈降により精製を繰り返し行い、感温性磁性粒子を２１質量％含む感温性磁性流体８５ｇを得た。
<Production of water-based temperature-sensitive magnetic fluid>
8.1 g of water, 10.6 g of 50% sodium dodecylbenzenesulfonate, 4.8 g of ethylene glycol, and 4.8 g of ethylene glycol monomethyl ether were uniformly stirred, and 47 g of the obtained water-containing temperature-sensitive magnetic particles were added, and the speed was increased for 1 hour. Stir to disperse the temperature-sensitive magnetic particles, and then add 30 g of water and stir at high speed for 30 minutes. Thereafter, purification was repeated by magnetic precipitation to obtain 85 g of a thermosensitive magnetic fluid containing 21 mass% of thermosensitive magnetic particles.
この感温性磁性流体のｐＨは７．５、飽和磁化は１７（ｍＴ）、粘度（２５℃）は３．１（ｍＰａ・ｓ）であった。 The temperature-sensitive magnetic fluid had a pH of 7.5, a saturation magnetization of 17 (mT), and a viscosity (25 ° C.) of 3.1 (mPa · s).
（動作試験）
図２に示す構成の磁性流体駆動装置を試作し、供試流体である非共沸混合磁性流体の駆動試験を行った。
磁場印加部としては、図３、図４に示す、流路垂直中心方向に磁化容易軸を持ち、着磁方向が互いに反対である２０×３０×１０ｔｍｍのネオジム磁石２個と４０×３０×５ｔｍｍのヨーク材ＳＳ４００から成る磁気回路を２個同極対向配置させたものを使用した。
この磁気回路の流路進行方向の磁場分布は、図５に示すように磁場強度の極大点が１個になる。
(Operation test)
A magnetic fluid driving device having the configuration shown in FIG. 2 was prototyped and a non-azeotropic mixed magnetic fluid driving test fluid was tested.
As the magnetic field application unit, two 20 × 30 × 10 tmm neodymium magnets having an easy magnetization axis in the direction perpendicular to the flow path and opposite to each other as shown in FIGS. 3 and 4 and 40 × 30 × 5 tmm are used. A magnetic circuit composed of two yoke materials SS400 having the same polarity opposite to each other was used.
As shown in FIG. 5, the magnetic field distribution in the flow path direction of this magnetic circuit has one maximum point of the magnetic field strength.
循環流路は、内径３ｍｍのテフロン（登録商標）チューブ、加熱管として、内径３ｍｍ、長さ４０．０ｍｍの銅管を使用し、全流路長さを、１２００ｍｍとした。 The circulation channel was a Teflon (registered trademark) tube with an inner diameter of 3 mm, a copper tube with an inner diameter of 3 mm and a length of 40.0 mm was used as a heating tube, and the total channel length was 1200 mm.
加熱部は、図４に示すように、上記磁気回路との相対位置を任意に変更可能な銅管で形成し、直流電源に接続した。
上記銅管の温度を赤外線温度計により測定し、その測定値が３０℃〜１００℃になる様に電流・電圧を調整した。
As shown in FIG. 4, the heating unit was formed of a copper tube whose relative position with respect to the magnetic circuit can be arbitrarily changed, and was connected to a DC power source.
The temperature of the said copper pipe was measured with the infrared thermometer, and the electric current and voltage were adjusted so that the measured value might be 30 to 100 degreeC.
上記循環流路に上記感温性磁性流体を封入して磁性流体駆動装置を作製した。
磁性流体駆動装置を用いて、銅管温度（磁性流体印加温度）を変化させて、感温性磁性流体の駆動試験をおこない、各々の温度での流量を測定した。
試験結果のグラフを図６に示す。
The temperature-sensitive magnetic fluid was sealed in the circulation channel to produce a magnetic fluid driving device.
Using a magnetic fluid driving device, the copper tube temperature (magnetic fluid application temperature) was changed to perform a temperature-sensitive magnetic fluid driving test, and the flow rate at each temperature was measured.
A graph of the test results is shown in FIG.
この様に、本発明の水系磁性流体は、消防法上の非危険物であり安全で、電子機器や自動車分野などの熱輸送駆動装置として多岐の用途に適用することが可能になる。
また、熱輸送駆動装置は、従来より流量が飛躍的に大きくすなわち熱輸送効率の高い装置を提供することが可能となる。
As described above, the water-based magnetic fluid of the present invention is a non-hazardous material under the Fire Service Act, is safe, and can be applied to various applications as a heat transport drive device in the field of electronic equipment and automobiles.
In addition, the heat transport drive device can provide a device having a significantly larger flow rate than that of the conventional device, that is, a device having high heat transport efficiency.
Claims (7)
上記感温性磁性粒子が、強磁性金属酸化物微粒子の表面にメルカプト酢酸、メルカプトプロピオン酸、メルカプトエタノールから選ばれる少なくとも一つのメルカプト基を含有する吸着剤が直接付着したものであることを特徴とする感温性磁性流体。 A temperature-sensitive magnetic fluid containing a temperature-sensitive magnetic particle and an aqueous dispersion medium,
The temperature-sensitive magnetic particles are characterized in that an adsorbent containing at least one mercapto group selected from mercaptoacetic acid, mercaptopropionic acid, and mercaptoethanol is directly attached to the surface of the ferromagnetic metal oxide fine particles. A temperature-sensitive magnetic fluid.
上記感温性磁性流体が、上記請求項１〜６のいずれか１つの項に記載の感温性磁性流体であることを特徴とする磁性流体駆動装置。 A circulation channel for circulating the temperature-sensitive magnetic fluid, a magnetic field application unit that applies a magnetic field to the temperature-sensitive magnetic fluid in the circulation channel, and a part of the magnetic field application unit that heats the magnetic field application unit A ferrofluid drive device comprising a heating unit for applying a temperature gradient to the thermophilic ferrofluid,
The temperature-sensitive magnetic fluid is the temperature-sensitive magnetic fluid according to any one of claims 1 to 6, wherein the magnetic fluid driving device is characterized.
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