阅读说明：本技术 磁粘性流体组合物 (Magnetic viscous fluid composition ) 是由 石崎裕久 落合明 于 2020-03-17 设计创作，主要内容包括：本发明提供一种磁性粒子的分散稳定性及流动性出色的磁粘性流体组合物。该磁粘性流体组合物包含磁性粒子、分散媒、粘度调整剂、中空粒子。所述中空粒子的平均一次粒径优选为5～500nm。所述中空粒子优选为从由碳粒子、二氧化硅、交联苯乙烯-丙烯酸所形成的群中选择的至少1种。所述粘度调整剂优选为从由蓖麻油、脂肪酸酰胺、聚烯烃、(甲基)丙烯酸酯所形成的群中选择的至少1种。(The invention provides a magnetic viscous fluid composition with excellent dispersion stability and fluidity of magnetic particles. The magnetic viscous fluid composition comprises magnetic particles, a dispersion medium, a viscosity modifier and hollow particles. The average primary particle diameter of the hollow particles is preferably 5 to 500 nm. The hollow particles are preferably at least 1 selected from the group consisting of carbon particles, silica, and crosslinked styrene-acrylic acid. The viscosity modifier is preferably at least 1 selected from the group consisting of castor oil, fatty acid amides, polyolefins, and (meth) acrylates.)

1. A magnetic viscous fluid composition comprising (A) magnetic particles, (B) a dispersion medium, (C) a viscosity modifier, and (D) hollow particles.

2. The magnetically viscous fluid composition of claim 1 wherein the hollow particles have an average primary particle size in the range of 5 to 500 nm.

3. The magnetically viscous fluid composition of claim 1 or 2 wherein the hollow particles are at least 1 selected from the group consisting of carbon particles, silica, crosslinked styrene-acrylic acid.

4. A magnetically viscous fluid composition according to any of claims 1 to 3 wherein (C) is at least 1 selected from the group consisting of castor oil, fatty acid amides, polyolefins, (meth) acrylates.

Technical Field

The invention relates to a magnetic viscous fluid composition. More particularly, the present invention relates to a magnetic viscous fluid composition for controlling frictional force between various mechanical devices such as a brake, a clutch, a vibration preventing device, and a damper of a vibration control device.

Background

Generally, a magnetic viscous fluid is prepared by dispersing magnetizable metal particles such as magnetic particles in a dispersion medium. The magnetic viscous fluid functions as a fluid when no magnetic field is applied. On the other hand, when a magnetic field is applied, the magnetic particles are agglomerated and thickened, and have a property of increasing internal stress.

Since the difference in specific gravity between the magnetic particles in the magnetic viscous fluid and the dispersion medium is large, the magnetic particles are likely to be precipitated. And the generation of hard sludge-like precipitates is easily caused by the cohesive force of the magnetic particles.

In this case, since the internal stress is reduced when the magnetic field is applied, it is required to improve the dispersion stability of the magnetic particles to suppress the precipitation of the magnetic particles. In addition, fluidity as a fluid must be satisfied.

As an example of improvement of such problems, patent documents 1 to 2 are known, for example. Patent document 1 is an example of using a clay mineral such as organobentonite or organolithium bentonite (hectorite). Patent document 2 is an example of using Neuburg silica (Neuburg silica).

Organobentonite, organolithium bentonite, and Neuburg silica (Neuburg silica) used in patent documents 1 and 2 are added as a thickener. However, satisfactory results in terms of dispersion stability and fluidity have not yet been obtained.

Disclosure of Invention

Problems to be solved by the invention

In view of the above-described situation, an object of the present invention is to provide a magnetic viscous fluid composition having excellent dispersion stability and fluidity of magnetic particles.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that the above problems can be solved by including a viscosity modifier and hollow particles in a magnetic viscous fluid comprising magnetic particles and a dispersion medium, and have completed the present invention.

That is, the magnetic viscous fluid composition of the present invention is characterized by containing (a) magnetic particles, (B) a dispersion medium, (C) a viscosity adjusting agent, and (D) hollow particles.

The average primary particle diameter of the hollow particles is preferably in the range of 5 to 500 nm. The hollow particles are preferably at least 1 selected from the group consisting of hollow carbon particles, hollow silica particles, and hollow crosslinked styrene-acrylic acid particles.

The viscosity modifier is preferably at least 1 selected from the group consisting of castor oil, fatty acid amides, polyolefins, and (meth) acrylates.

Effects of the invention

The present invention provides a magnetic viscous fluid composition having excellent dispersion stability and fluidity of magnetic particles.

Drawings

Fig. 1 is an electron microscope image of (a) magnetic particles (carbonyl iron) taken by a scanning electron microscope, at a magnification of 45,000.

FIG. 2 is an electron microscope image taken by a scanning electron microscope at a magnification of 20,000 times after removing a dispersion medium from the magnetically viscous fluid composition of comparative example 1.

FIG. 3 is an electron microscope image taken by a scanning electron microscope at a magnification of 100,000 times after removing the dispersion medium from the magnetically viscous fluid composition of example 1.

Detailed Description

Hereinafter, the magnetic viscous fluid composition of the present invention will be described in detail.

In the present specification, the term "to" indicating a numerical range means a range including numerical values respectively describing the upper limit value and the lower limit value thereof. In the numerical range, when only the upper limit value is expressed in the unit, the lower limit value and the upper limit value are expressed in the same unit.

In the numerical ranges recited in the present specification, the upper limit or the lower limit of a certain numerical range may be replaced with the upper limit or the lower limit of another numerical range recited in a stepwise manner.

In the numerical ranges described in the present specification, the upper limit or the lower limit described in a certain numerical range may be replaced with the numerical values shown in the examples.

In the present specification, the content or the content of each component in the composition means the content or the content of the total of a plurality of substances present in the composition when the plurality of substances corresponding to each component are present in the composition, unless otherwise specified.

(magnetic viscous fluid composition)

The magnetic viscous fluid composition of the present invention contains (a) magnetic particles, (B) a dispersion medium, (C) a viscosity adjusting agent, and (D) hollow particles.

Generally, the term "colloidal fluid" refers to a fluid in which magnetic particles are dispersed in a dispersion medium.

The magnetic viscous fluid composition of the present invention contains (a) magnetic particles, (B) a dispersion medium, (C) a viscosity adjusting agent, and (D) hollow particles, and thus can suppress precipitation of the magnetic particles and has excellent fluidity.

The reason is not clear, but is presumed as follows.

As is clear from a comparison between fig. 2 and fig. 3, the hollow particles are less visible even when the magnification of fig. 3 is as high as 5 times. Therefore, it is presumed that this is because the magnetic particles integrated with the hollow particles are coated with the viscosity modifier. Therefore, detachment of the hollow particles from the magnetic particles is suppressed. It is therefore presumed that, as a result, precipitation of the magnetic particles is suppressed to improve dispersion stability and fluidity.

Hereinafter, each component contained in the magnetic viscous fluid composition will be described.

(A) Magnetic particles

The magnetic viscous fluid composition of the present invention contains magnetic particles. The permeability can be selected according to the purpose. Examples include: magnetite, carbonyl iron, gamma-iron oxide, manganese ferrite (mangannese ferrite), cobalt ferrite, or a strongly magnetic oxide thereof on which zinc or nickel is imprinted, such as a ferrichloride or barium ferrite; strong magnetic metals such as iron, cobalt, rare earth and the like; nitriding a metal; and various alloys such as Sendust (registered trademark), Permalloy (registered trademark), and Supermalloy (registered trademark). Among these, carbonyl iron is preferable from the viewpoint of small coercive force, large magnetic permeability, and soft magnetic material.

The magnetic particles can be used alone in 1 kind, or in combination with more than 2 kinds.

In the magnetic viscous fluid composition of the present invention, when a magnetic field is applied from the outside, the dispersed magnetic particles are aligned in the direction of the magnetic field and aggregated into a mass, thereby thickening the mass, and changing the flow characteristics and yield stress of the mass. In order to show this, the average particle diameter of the magnetic particles may be set. Specifically, the thickness is preferably in the range of 0.1 to 100. mu.m. More preferably 1 to 60 μm. Particularly preferably 5 to 50 μm. The shape of the magnetic particles is preferably spherical or nearly spherical in view of easy dispersion.

The average particle size of the magnetic particles is an average primary particle size measured by a laser diffraction/scattering particle size distribution measuring apparatus.

The content ratio of the magnetic particles is preferably in the range of 30 to 90% by mass with respect to the total amount of the magnetic viscous fluid composition of the present invention. More preferably 40 to 80 mass%. By setting the content ratio of the magnetic particles to the total amount of the magnetic viscous fluid composition of the present invention to a range of 30 to 90 mass%, the magnetic viscous fluid composition can exert a function as a fluid in addition to obtaining a necessary shear stress when a magnetic field is applied.

(B) Dispersion medium

The magnetically viscous fluid composition of the present invention contains a dispersion medium. The magnetic particles are not particularly limited as long as they are liquid at room temperature (25 ℃) and can be dispersed. Examples include: a hydrocarbon solvent such as an alpha olefin, an isoalkane, an n-alkane, and a halogenated hydrocarbon, an ester solvent, a glycol solvent, and a silicon solvent. As the α -olefin, there may be mentioned: 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, etc. Among them, preferred are alpha-olefins having 10 to 14 carbon atoms such as 1-octene, 1-decene, 1-dodecene and the like. Further, as the glycol-based solvent, there can be mentioned: polyethylene glycol, polypropylene glycol, polybutylene glycol, or an ethylene oxide-propylene oxide copolymer, a propylene oxide-butylene oxide copolymer, and derivatives thereof.

The dispersion medium may be used alone in 1 kind, or 2 or more kinds may be used in combination if the compatibility is good.

The dynamic viscosity of the dispersion medium at 40 ℃ is preferably 2-5000 mm²(ii) a range of/s. More preferably 5 to 2000mm²(ii) a range of/s. Further preferably 5 to 1000mm²(ii) a range of/s. The dynamic viscosity of the dispersion medium at 40 ℃ is set to be 2-5000 mm²The range of/s is capable of increasing the ignition point of the dispersion medium, suppressing evaporation, and facilitating the dispersion of the magnetic particles in the dispersion medium. The kinematic viscosity is measured by JIS K2283: 2000 dynamic viscosity test method.

The content ratio of the dispersion medium is preferably set in the range of 5 to 30% by mass, and more preferably in the range of 9 to 25% by mass, based on the total amount of the magnetic viscous fluid of the present invention.

(C) Viscosity modifier

The magnetic viscous fluid composition of the present invention contains a viscosity modifier. Examples include: castor oil, hydrogenated castor oil, fatty acid amide, beeswax, carnauba wax, benzylidene sorbitol (benzylidene sorbitol), metal soap, oxidized polyethylene, sulfate-based anionic activator, polyolefin, (meth) acrylate, polyisobutylene, ethylene-propylene copolymer, polyalkylstyrene (polyalkylstyrene), and the like.

Among these, castor oil, fatty acid amide, polyolefin, and (meth) acrylate are preferable because they have an excellent effect of suppressing precipitation of magnetic particles and also easily adjust the viscosity of the magnetically viscous fluid composition.

The viscosity modifier can be used alone in 1 kind, can also be combined with more than 2 kinds.

Examples of the fatty acid amide include: octadecanamide, oleic acid amide (oleic amide), erucic acid amide (erucic acid amide), methylene bis octadecanamide (methylene bis octadecanamide), ethylene bis octadecanamide (ethylene bis octadecanamide), and the like. Among them, octadecanamide and oleic acid amide are preferable. The fatty acid amide may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The polyolefin preferably has a number average molecular weight of 2,000 to 7,000. Setting the range is preferable because the precipitation suppression effect of the magnetic particles is excellent and the viscosity of the magnetic viscous fluid composition can be easily adjusted.

The content ratio of the viscosity modifier is preferably set in the range of 0.5 to 10% by mass, and more preferably in the range of 0.7 to 9% by mass, based on the total amount of the magnetic viscous fluid composition of the present invention. The content ratio of the viscosity modifier is set to a range of 0.5 to 10% by mass relative to the total amount of the magnetic viscous fluid composition of the present invention, so that the sedimentation of the magnetic particles can be suppressed and the fluidity can be maintained.

(D) Hollow particles

The magnetic viscous fluid composition of the present invention contains hollow particles. Examples include: hollow carbon particles, hollow silica particles, hollow crosslinked styrene acrylic acid particles, and the like. Among them, hollow carbon particles are preferable. In addition, the hollow particles mean particles having a hollow structure. The hollow structure includes not only a structure in which the inside surrounded by the outer shell is completely hollow but also a porous structure in which a plurality of cavities are formed in grooves in the particle interior.

Examples of the hollow carbon particles include: carbon particles obtained by thermally decomposing Lignin (Lignin) (hereinafter, also referred to as "Lignin black (registered trademark)"), ketjen black (registered trademark) which is hollow carbon black, carbon nanocapsules, nanoporous carbon, and the like.

The wood black is a commercially available product. For example, wood black manufactured by king paper company is exemplified.

Ketjen black (Ketjen black) is commercially available. Examples thereof include ketjen black EC300J and EC600JD manufactured by LION SPECIALTY CHEMICALS.

The nanoporous carbon can be commercially available. For example, NPC-H, NPC-L, NPC-N, manufactured by Neo-Mond, may be mentioned.

Commercially available hollow silica particles can be used. Examples thereof include SiliNax (registered trade name) having an average primary particle diameter of 100nm, manufactured by Nissan corporation.

Commercially available crosslinked styrene-acrylic acid particles can be used. For example, SX866 and SX868, which are manufactured by JSR, have average primary particle diameters of 300nm and 500nm, respectively.

The hollow particles can be used alone in 1 kind, also can be combined with more than 2 kinds.

The hollow particles preferably have a primary average particle diameter in the range of 5 to 500 nm. The lower limit is more preferably 10nm, and particularly preferably 20 nm. The upper limit is more preferably 300nm, and particularly preferably 100 nm. By setting the primary particle diameter of the hollow particles in the range of 5 to 500nm, precipitation of the magnetic particles is suppressed, and detachment of the hollow particles from the magnetic particles is also suppressed. The average particle diameter of the hollow particles is not particularly limited, and means an average outer diameter.

The content ratio of the hollow particles is set to be preferably in the range of 0.2 to 0.8 mass%, and more preferably in the range of 0.3 to 0.7 mass%, relative to the total amount of the magnetic viscous fluid composition. The content ratio of the hollow particles is set to be in the range of 0.2 to 0.8 mass% relative to the total amount of the magnetic viscous fluid composition, so that the magnetic viscous fluid composition with excellent dispersion stability and fluidity can be obtained.

Other ingredients

In the magnetic viscous fluid composition of the present invention, the above-mentioned components may be added, and various other components may be used in combination according to the purpose of the present invention, as long as the effects of the present invention are not impaired. Examples of the other components include: micro magnetic particles, a dispersant, a pour point depressant, an extreme pressure agent, an antirust agent, an antioxidant, an anticorrosive agent, a metal deactivator, an antifoaming agent, and the like.

The fine magnetic particles may be made of the same material as the magnetic particles, but have an average particle diameter of 5 to 50nm, preferably 7 to 40 nm.

The average particle diameter of the fine magnetic particles is an average primary particle diameter measured by a dynamic light scattering method.

The dispersant is added to improve the dispersibility of the dispersion medium for the magnetic particles. As the dispersant, a known surfactant, a polymer dispersant, or the like can be suitably used. Among them, a surfactant is preferable from the viewpoint of dispersibility.

Examples of the surfactant used as the dispersant include: anionic surfactants of hydrocarbon compounds having polar groups such as a carboxyl group, a hydroxyl group, and a sulfonic group, such as petroleum sulfonic acid or a salt thereof, synthetic sulfonic acid or a salt thereof, eicosyl naphthalene sulfonic acid (eicosyl naphthalene sulfonic acid) or a salt thereof, polybutenyl succinic acid (polybutene succinic acid) or a salt thereof, and sinapic acid or a salt thereof; nonionic surfactants such as polyoxyalkylene lauryl ether (polyoxyalkylenelauryl ether), polyoxyalkylene decyl ether (polyoxyalkylenedecylether), polyoxyalkylene isodecyl ether (polyoxyalkyleneisodecylether), polyoxyalkylene tridecyl ether (polyoxyalkylenetridecyl ether), polyoxyethylene lauryl ether, polyoxyethylene decyl ether (polyoxyalkylenedecylether), polyoxyethylene isodecyl ether (polyoxyalkyleneisodecylether), polyoxyethylene tridecyl ether (polyoxyethylenetridecyl ether), polyoxyethylene alkyl ether (polyoxyethylenealkyl ether), polyoxyethylene nonylphenyl ether (polyoxyethylenenonylphenyl ether), and polyoxyethylene nonylphenyl ether (polyoxyethylenenonylphenyl ether); amphoteric surfactants having both a cationic moiety and an anionic moiety in the molecular structure, such as alkyldiaminoethylglycine (alkyldiaminoethylglycine); and the like.

The surfactant may be used alone in 1 kind, or in combination of 2 or more kinds.

(method for producing magnetic viscous fluid)

The method for producing the magnetic viscous fluid composition of the present invention is not particularly limited. For example, the magnetic particles, the dispersion medium, the viscosity modifier, the hollow particles, and other components added as needed are mixed by a processing machine such as a homogenizer, a bead mill, or a mechanical mixer, which imparts a high shear force. In addition, heating or cooling may be performed as necessary in the production of the magnetic viscous fluid.