KR102073255B1 - Magnetorheological Fluid - Google Patents

Abstract

In the present invention, by including a mixture of branched hydrocarbon-based oils and linear hydrocarbon-based oils as carrier oils together with magnetic particles, a magnetic rheological fluid is provided that exhibits significantly improved storage stability.

Description

Magnetic rheological fluid

The present invention relates to a magnetorheological fluid having excellent storage stability.

When magnetic field is applied to magnetic particles dispersed in a solvent, magnetic particles are polarized according to the applied magnetic field to generate attraction between magnetic dipoles, and form a chain-like structure in the direction of the applied magnetic field. As a result, the formed chain structures exhibit a resistance to the flow of fluid and external shear forces, thereby increasing the rheological viscosity and yield stress.

Magnetorheological Fluid is a substance that changes from a quasi-liquid state to a quasi-solid state due to a magnetic rheological phenomenon when a magnetic field is applied, and is mainly used for dampers or shock absorbers for vehicles. It is applied to shock absorbers, clutches, brakes, building dustproof designs, and vibration prevention of robots.

Magnetic rheology fluid is usually prepared by dispersing magnetic particles in carrier oil, in which case the magnetic stress is uniformly dispersed in the carrier oil so that the shear stress characteristics of the magnetic rheology fluid are well represented. If the magnetic particles do not disperse well, the magnetic particles aggregate to greatly increase the viscosity of the magnetic rheological fluid, and the shear stress is reduced.

According to the general particle magnetic dipole mechanism, soft magnetic materials such as high-purity iron with high polarization tendency and high magnetic properties should be used as magnetic particles, but most of these materials have high density and unstable surface properties. There is this. In particular, high density is a major obstacle to the presence of magnetic rheological fluid as a normally stable fluid, and also causes a problem that redispersion is difficult when the magnetic field is lowered or removed.

In addition, since the magnetic rheological fluid must have stable dispersion fluid characteristics in a state where a magnetic field is not applied, stable dispersion of magnetic particles in the magnetic rheological fluid is important. However, due to the large density difference between the carrier oil and the magnetic particles, there is a problem in that the stability is low, such as forming a gel (gel) that does not loosen even when shearing (shear) by the magnetic particles settled in the liquid phase.

Accordingly, the present invention is to solve the problems of the prior art, to provide a magnetic rheological fluid showing excellent storage stability.

In order to solve the above problems, according to an embodiment of the present invention, the magnetic particles and the carrier oil, the carrier oil provides a magnetic rheology fluid comprising a branched hydrocarbon-based oil and a linear hydrocarbon-based oil. .

The magnetorheological fluid according to the present invention exhibits significantly improved storage stability while maintaining excellent viscosity characteristics and dispersibility, thereby controlling vehicle damper systems, shock absorbers, engine mounts, brakes, and the like. It can have a particularly advantageous effect when applied to the system, the flow control valve system and positioning, and the construction damping design device and the anti-vibration device of the robot.

Figure 1 is a graph of the redispersion energy after storage of the magnetic rheology liquid of Example 1 and Comparative Example 1 for 60 days, respectively.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. As used herein, the terms "comprise", "comprise" or "have" are intended to indicate that there is a feature, step, component, or combination thereof that is practiced, and that one or more other features or steps, It should be understood that it does not exclude in advance the possibility of the presence or addition of components, or combinations thereof.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to the specific form disclosed, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

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

Magnetic rheology fluid according to an embodiment of the present invention,

Magnetic particles; And

Includes carrier oil,

The carrier oil includes a branched hydrocarbon oil and a linear hydrocarbon oil.

In the present invention, the linear hydrocarbon oil refers to a form in which the carbon-to-carbon bonds forming the central skeleton of the oil are linear or pseudo-linear. In addition, the branched hydrocarbon-based oil is called a branched structure having one or more chain branches formed by branching a carbon chain from a linear central skeleton.

Linear hydrocarbon oils have the advantage of improving flowability of magnetic rheological fluids due to their lower viscosity due to alignment due to shearing forces. However, the structure is easy to pack and prevents sedimentation when magnetic particles settle. It does not provide stability, and when included alone as a carrier oil in the magnetorheological fluid, there is a concern that the storage stability may be increased by increasing the redispersion energy of the magnetorheological fluid. On the other hand, in the case of branched hydrocarbon-based oils, the redispersion energy of the magnetic rheology fluid may be reduced, and the bulky structure may provide stability to sedimentation of the magnetic particles by steric stabilization, but when used alone. There exists a possibility that a viscosity may rise or it may impair flowability.

Accordingly, the magnetorheological fluid according to an embodiment of the present invention includes a mixture of heterogeneous hydrocarbon oils having different structures as carrier oils, thereby reducing redispersion energy of the magnetorheological fluid while maintaining excellent viscosity characteristics. It can exhibit excellent storage stability.

Furthermore, by optimizing the content of the branched hydrocarbon-based oil and linear hydrocarbon-based oil, it is possible to further improve the storage stability. Specifically, the magnetorheological fluid according to an embodiment of the present invention may include a branched hydrocarbon oil and a linear hydrocarbon oil in a weight ratio of 99: 1 to 25:75, and more specifically, a branched hydrocarbon oil. Magnetic particles when the base oil is contained in a larger amount than linear hydrocarbon-based oil, specifically, in a weight ratio of 99: 1 to 60:40, or 90:10 to 60:40, or 90:10 to 75:25. In addition to improving the stability of sedimentation, the effect of reducing the redispersion energy of the magnetorheological fluid and thus improving the storage stability may be more significant.

 In the present invention, the redispersion energy of the magnetorheological fluid is a parameter representing the storage stability of the magnetorheological fluid, and after the magnetorheological fluid is stored for a period of time, a 5 mm x 5 mm square proof is introduced at a speed of 1 mm / s through a texture analyzer. While measuring the force taken, the power is converted into energy. The greater the redispersion energy, the more the particles aggregate and increase the resistive force, and the greater the redispersion energy, the poor the storage stability.

In addition, in the branched and linear hydrocarbon oils, the storage stability and characteristics of the magnetorheological fluid may be further improved by controlling the type, molecular weight, molecular weight, distribution, or number of side chains in addition to the structure.

Specifically, the branched hydrocarbon-based oil may be a branched poly-alpha olefin, more specifically 1-decene, 1-dodecene, 1- tetradecene, 1- hexadecene, 1-octadecene and the like It may be a branched polymer of 6 to 30 alphaolefins, of which poly (1-decene) may be used.

These branched poly-alphaolefins can exhibit low viscosity at low temperatures to improve the storage stability at low temperatures of magnetic rheology fluids.

In addition, the branched hydrocarbon-based oil may be a CH content of the branched chain, that is, the side chain of 5 to 15% by weight based on the total weight of the branched hydrocarbon-based oil. When the CH content of the side chain is too high, the length of the branch may be short, so that the sedimentation stability may not be expressed, or the molecular weight may be large, resulting in high viscosity, which may lower the fluidity or flowability. Due to the structure, the stability of the magnetic particles against sedimentation can be improved. Considering the remarkable effect of the improvement effect according to the CH content control of the side chain in the branched hydrocarbon-based oil, the CH content of the side chain in the branched hydrocarbon-based oil may be 7 to 11% by weight.

In addition, the branched hydrocarbon-based oil may have a weight average molecular weight (Mw) of more than 500 g / mol and 1500 g / mol or less, more specifically, under the conditions that meet the above-described CH content of the side chain, the weight average molecular weight of 600 To 1400 g / mol, more specifically, 650 to 1300 g / mol. When the branched hydrocarbon oil has a weight average molecular weight in the above range, the more controlled structure can improve the stability to sedimentation of the magnetic particles, and furthermore, in addition to the CH content of the side chain, When having a weight average molecular weight, it is possible to further reduce the redispersion energy of the magnetorheological fluid.

For example, the branched hydrocarbon-based oil may be obtained commercially available products that meet all the above conditions, such as INEOS Durasyn ^TM 164 or 0 Sigma-Aldrich ^TM 462349.

In addition, in this invention, a weight average molecular weight (Mw) is polystyrene conversion molecular weight analyzed by gel permeation chromatography (GPC).

In addition, the linear hydrocarbon-based oil may be a CH content of the branched chain, that is, the side chain with respect to the total weight of the linear hydrocarbon-based oil is less than 5% by weight. By having the CH content of the side chains less than 5% by weight, linear or pseudo-linear, the redispersion energy of the magnetorheological fluid can be reduced when used in combination with the branched hydrocarbon-based oils described above. Considering the remarkable effect of the improvement effect according to the CH content control of the side chain in the linear hydrocarbon-based oil, the CH content of the side chain in the linear hydrocarbon-based oil may be 3% by weight or less or 1% by weight or less.

In addition, the linear hydrocarbon oil may have a weight average molecular weight (Mw) of 500 g / mol or less, and more specifically, 100 to 500 g / mol, more specifically, under conditions that satisfy the above-described CH content condition of the side chain. May be from 300 to 500 g / mol. When the linear hydrocarbon oil has a weight average molecular weight in the above-described range along with the CH content condition of the side chain, it can have a more controlled viscosity to further reduce the redispersion energy of the magnetorheological fluid.

Specifically, the linear hydrocarbon oil may be a mineral oil that is a mixture of a hydrocarbon-based compound in a liquid state derived from petroleum, and more specifically, a paraffinic oil having 20 to 40 carbon atoms satisfying the above-described CH content condition of the side chain. It may be to include. For example, as the linear hydrocarbon-based oil, a product satisfying all the above conditions, such as Sigma-Aldrich 330779 ^™ , may be commercially available.

On the other hand, in the present invention, the CH content of the side chain in the branched and linear hydrocarbon-based oil can be analyzed using conventional methods using GPC column analysis and NMR analysis, in the present invention using a CDCl ₃ solvent After melting and sampling, it can be measured by HSQC and 13C NMR.

In addition, in the magnetic rheological fluid according to an embodiment of the present invention, the magnetic particles are iron powder, carbonyl iron powder, ferrite powder (for example, MnZn or NiZn ferrite, etc.), gas atomized iron powder (gas-atomized) iron powder, and water-atomized iron powder.

In particular, the carbonyl iron powder (CIP) has a Fe purity of 97% or more, more specifically 99% or more and a high saturation magnetic flux density. It may exhibit a high shear stress, and because it is excellent in chemical stability, it is resistant to oxidation in the air and may be more preferable because there is no concern about corrosion during the manufacturing process and consequent deterioration of magnetic properties.

In addition, the magnetic particles may have various shapes such as spherical shape, rod shape, or scale shape, but may be more preferable since the magnetic particles may exhibit even rheological properties due to less variation in magnetic properties due to changes in particle shape.

In addition, in the magnetic particles, the particle size affects the rheology of the magnetic rheological fluid. Usually, the larger the particle size, the higher the yield stress. However, if the size of the particles is too large, precipitation is likely to occur, and as a result, the stability of the fluid may be degraded. Thus, in the present invention, the magnetic particles may be spherical particles having an average particle size (D ₅₀ ) of 1 μm to 50 μm. When having a particle size in the above range, the magnetic flow characteristics (magnetorheological properties) is excellent, and the stability of the magnetic rheological fluid can be maintained. More specifically, the magnetic particles may be spherical particles having an average particle size (D ₅₀ ) of 2 ㎛ to 30 ㎛.

In the present invention, the average particle size (D ₅₀ ) may be defined as the particle diameter at 50% of the particle diameter distribution, and may be measured by a conventional particle size measuring method such as a laser diffraction method. have.

In addition, in the magnetic rheological fluid according to an embodiment of the present invention, the magnetic particles, an organic compound such as a silane compound; Inorganic oxide fine particles such as silica (SiO _x , 0 <x ≦ 2) and the like; It may be surface treated with one or more materials such as metals or polymers. As a result of the surface treatment, not only the compatibility between the magnetic particles is increased, but also the density of the magnetic particles is reduced, thereby reducing the density difference between the carrier oil and the magnetic particles, thereby improving dispersibility. In addition, the wettability between the magnetic particles and the carrier oil is improved, so that dispersibility and compatibility are improved, and as a result, high shear stress can be exhibited. Among these, when the surface treatment with silica of SiO ₂ , the wettability is improved in the solvent, and the compatibility is increased, thereby showing excellent dispersion stability.

The surface treatment may be performed by physically and uniformly mixing the magnetic particles and the surface treatment raw material using a mixer such as a roller mixer, a resonance acoustic mixer, or a shaker. In the case of using a ball milling commonly used for surface treatment, deformation such as distortion of magnetic particles may occur.

In the case of surface treatment with silica, the silica is applied to at least a part of the surface of the magnetic particles, more specifically, the entire surface of the magnetic particles in a particulate state to form a surface treatment layer. In this case, the silica particles coated on the magnetic particle surface may have an average particle size (D ₅₀ ) of 100 nm or less, specifically 5 to 100 nm, and more specifically 5 to 20 nm. When the silica has the above-described particle size, it is possible to form the surface treatment layer with a uniform thickness on the surface without deteriorating the properties of the magnetic particles.

In addition, the silica may be applied to the surface of the magnetic particles in an amount of 0.05ppm or more and less than 0.2ppm. At this time, if the silica content to be applied is too small, the addition effect is insignificant, the dispersibility and compatibility is lowered, if the content is too high, there is a fear of aggregation between the magnetic particles. More specifically, it is preferable to apply | coat in the form of a shell with respect to the whole magnetic particle surface in the quantity of 0.1 ppm or more and 0.15 ppm or less, and form a surface treatment layer.

As described above, the silica surface-treated magnetic particles may be included in an amount of 70 wt% or more and less than 100 wt%, specifically 70 to 90 wt%, based on the total weight of the magnetic rheology fluid. When included in the above content range may exhibit excellent shear stress properties with an appropriate viscosity.

In addition, the magnetic rheological fluid according to the embodiment of the present invention may further include a dispersant to improve the dispersibility of the magnetic particles.

As the dispersant, one or more of aliphatic alcohols and aliphatic diols may be used. More specifically, the aliphatic alcohol may be a fatty alcohol having 6 to 10 carbon atoms such as 1-Hexanol, 1-Octanol, and 1-Decanol, and the aliphatic diol may have 6 to 10 carbon atoms such as 1,2-octandiol or 1,2-decandiol. Aliphatic diols. Compared with conventional polyester and alkyd resins, these dispersants are better adsorbed on the surface of the magnetic particles and can improve dispersibility without forming agglomerates (gels) of the magnetic particles even during long-term storage. Properties can be improved.

The dispersant may be included in an amount of 0.01 to 10% by weight, or 0.05 to 5% by weight based on the total weight of the magnetorheological fluid. If the content of the dispersant is too high, there is a possibility that the long-term stability is lowered due to the increase in viscosity, but when included in the above content range, the dispersibility of the magnetic particles is greatly improved, thereby improving the flow characteristics of the magnetic rheological fluid without fear of lowering the long-term stability. It can be further improved.

In addition, in addition to the above materials, the magnetic rheological fluid according to the exemplary embodiment of the present invention may include surfactants, metal salts, inorganic clays, organic clays, water, in order to improve the dispersion stability of the magnetic particles or to prevent friction wear with the parts. Additives such as antioxidants, antiwear agents, preservatives or thickeners may optionally further comprise one or more. These additives may be appropriately added within a range that does not deteriorate the properties of the magnetorheological fluid, and specifically, may be included in an amount of 10% by weight or less based on the total weight of the magnetorheological fluid.

Such magnetic rheological fluids can be prepared by dispersing silica surface treated magnetic particles in a carrier oil in the presence of a selective dispersant.

In this case, in order to increase dispersibility of the magnetic particles in the carrier oil, the homogenization process may be selectively performed after the addition of the magnetic particles into the carrier oil, and the homogenization process may be performed using a conventional stirring unit or the like.

Magnetic rheological fluid according to an embodiment of the present invention having the configuration as described above, due to the surface treatment of the magnetic particles to improve the compatibility between dispersing stability and dissimilar powder, excellent in physical properties such as viscosity, storage stability, shear stress Effect.

Specifically, the magnetorheological fluid has a viscosity of 15,000 cP or less, more specifically 7,000 cps or less, more specifically 5,500 cps or less, and a viscosity of 1,500 cps or less, more specifically, at a temperature of 40 ° C. at a speed of 1 rpm. In particular, it exhibits low viscosity at 1,000 cps or less, more specifically 950 cps or less. Thixotropic index (Thixo. Index) is 5 or more, more specifically 5 to 7, even more specifically 5 to 6. The magnetorheological fluid has a redispersion energy of less than 0.3 mJ, more specifically 0.2 mJ or less, and more specifically 0.1 to 0.2 mJ, even after prolonged storage for 60 days at a temperature of 20 ° C to 30 ° C and 1 atmosphere. , Excellent storage stability.

These excellent viscosity properties and significantly improved storage stability make it possible to control dampers, shock absorbers, engine mounts and brakes, valves for flow control and positioning. And, because it can be manufactured by adjusting the shear stress in accordance with the characteristics of the various components that require variable control of the shear stress, such as construction or anti-vibration design device for construction and robot anti-vibration device, its application is very advantageous.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited thereto.

The materials used in the Examples and Comparative Examples below are as follows:

Carbonyl Iron: Spherical, Average Particle Size (D ₅₀ ): 6 μm

Silica Particles: Spherical, Average Particle Size (D ₅₀ ): 12 nm

Branched hydrocarbon oil: Mw 990 g / mol, CH content of the side chain 10% by weight poly (1-decene) (Sigma-Aldrich 462349 ^TM )

Linear hydrocarbon oil (A): Mw 470 g / mol, mineral oil A with 2% by weight of CH content in the side chain (Sigma-Aldrich 330779 ^TM )

Linear hydrocarbon oil (B): Mw 800 g / mol, CH content of the side chain 2% by weight mineral oil B (Sigma-Aldrich 330760 ^TM )

Example 1

10 kg of carbonyl iron and 0.0012 g of silica particles were mixed, and then milled at a speed of 60 rpm using a roll mill for 1 hour. As a result, carbonyl iron surface-treated with silica particles was prepared (average particle size (D ₅₀ ) of silica: 12 nm, surface treatment: 0.12 ppm).

15.7 g of carrier oil was prepared by mixing poly (1-decene) as a branched hydrocarbon oil and mineral oil as a linear hydrocarbon oil (A) in a weight ratio of 75:25. Here, 0.08 g of 1-octanol is used as a dispersant, 0.01 g of zinc dithiophosphate (ZDDP) as an antioxidant, 0.05 g of Hexadecyl trimethyl ammonium bromide as a preservative, and 0.01 g of Molybdenum acetate as a preservative, and 250 rpm using an orbital shaker. After homogeneous mixing for 5 minutes, the surface-treated carbonyl iron 80 g was added and homogeneously mixed at 250 rpm for 3 hours using an orbital shaker. As a result, a magnetorheological fluid was obtained.

Examples 2-6, and Comparative Examples 1-3

A magnetic rheology fluid was prepared by the same method as in Example 1, except that the composition of Table 1 was used.

Weight ratio of branched oil / linear oil Types of Linear Hydrocarbon Oils Surface treatment of magnetic particles Dispersant Example 1 75:25 A U U Example 2 75:25 A U radish Example 3 50:50 A U U Example 4 25:75 A U U Example 5 75:25 B U U Example 6 75:25 A radish U Comparative Example 1 0: 100 A U U Comparative Example 2 0: 100 B U U Comparative Example 3 100: 0 - radish U

Experimental Example

The thixotropic index, viscosity, sedimentation degree and redispersion energy were measured for the magnetic rheological fluids prepared in Examples and Comparative Examples, respectively. The results are shown in Table 2 below.

1) Thixotropic index (Thixo.index): Toki sangyo TV-22, Spindle # 6 was used to measure the viscosity of 1 rpm and 10 rpm at 40 ℃, divided by the viscosity value of 10 rpm by the viscosity value of 1 rpm Defined by value.

2) Viscosity: Toki sangyo TV-22, Spindle # 6 was used to measure the viscosity of 1 rpm and 10 rpm at 40 ℃.

3) Sedimentation degree (%): The magnetic rheological fluid prepared in Examples and Comparative Examples was put into a test tube having a diameter of 10 mm and 150 mm, respectively, and the sinking height of the magnetic powder was measured after 7 days, 20 days and 60 days. The sedimentation rate and dispersibility were evaluated, and the lower the value, the slower the sedimentation rate, and the slower the sedimentation, the higher the dispersibility. Sedimentation degree is calculated according to the following equation (1).

[Equation 1]

Sedimentation intensity = (Ha-Hb) / Ha * 100%

In Equation 1, Ha represents an initial height and Hb represents a sinked height after 7 days, 20 days or 60 days of storage.

4) Redispersion energy (mJ): Resistance in the magnetic powder layer settled after 7 days, 20 days and 60 days after the magnetic rheological fluids prepared in Examples and Comparative Examples were put in a test tube having a diameter of 10 mm and a height of 150 mm, respectively. The energy was measured by inputting a 5 mm x 5 mm square proof with a texture analyzer at a speed of 1 mm / s.

Thixo.index Viscosity (mPs) Sedimentation degree (%) Redispersion energy (mJ) 1 rpm 10 rpm 7 days later After 20 days 60 days later 7 days later After 20 days 60 days later Example 1 5.8 5360 920 8 11 19 0.16 0.17 0.18 Example 2 5.1 4840 950 10 18 22 0.17 0.18 0.20 Example 3 6.4 6040 950 9 13 20 0.18 0.21 0.26 Example 4 6.8 6400 940 12 17 25 0.21 0.26 0.27 Example 5 5.6 5850 1040 7 10 17 0.20 0.22 0.27 Example 6 10.5 13100 1250 6 9 13 0.22 0.24 0.29 Comparative Example 1 1.2 610 500 14 19 27 0.22 0.30 0.35 Comparative Example 2 2.6 2840 1090 12 16 23 0.20 0.27 0.31 Comparative Example 3 9.7 16570 1700 5 7 11 0.23 0.26 0.30

Figure 1 is a graph of the redispersion energy after storage of the magnetic rheological fluid of Example 1 and Comparative Example 1 60 days.

As a result of the experiment, the magnetic rheological fluid of Examples 1 to 6, including a mixture of a branched hydrocarbon oil and a linear hydrocarbon oil, as a carrier oil, was a comparative example using a branched hydrocarbon oil or a linear hydrocarbon oil alone. Comparing with 1 to 3, it can be seen that even after long-term storage for 60 days shows a low redispersion energy of less than 0.3 mJ having improved storage stability.

Examples 1 to 5 in which the magnetic particles were surface-treated, as compared with Example 6 in which the magnetic particles were not surface-treated, had a lower redispersion energy, a viscosity at 1 rpm and a viscosity at 1200 rpm or less at 1200 rpm. Was significantly reduced. From this, it can be seen that the use of magnetic particles surface-treated with a mixture of branched hydrocarbon oil and linear hydrocarbon oil can further improve the viscosity characteristics and storage stability.

In addition, Examples 1 and 2 in which magnetic particles surface-treated with a mixture of branched hydrocarbon oils and linear hydrocarbon oils were used, but branched hydrocarbon oils were used more than linear hydrocarbon oils, had a viscosity at 1 rpm. Is less than 6000 cps, the viscosity is less than 1000 cps at 10 rpm, and shows a significantly reduced redispersion energy of 0.2 mJ or less even after prolonged storage for 60 days. It can be seen that it has more improved viscosity properties and storage stability compared to Examples 3 and 4 with more oil.

In addition, although Example 5 uses more branched hydrocarbon-based oils than linear hydrocarbon-based oils, the viscosity and redispersion energy are somewhat lower than those of Examples 1 and 2 due to the high weight average molecular weight of the linear hydrocarbon-based oils. Increased. However, Examples 3 and 4 showed the same level of viscosity and redispersion energy, and it can be seen that the dispersion is greatly improved in terms of sedimentation degree.

In addition, Example 1, which further includes a dispersant, exhibits lower values in terms of viscosity, sedimentation, and redispersion energy than Example 2, and further inclusion of the dispersant improves viscosity characteristics, dispersibility, and storage stability. can confirm.

Claims (19)

Magnetic particles; And
Contains carrier oil,
The carrier oil comprises a branched hydrocarbon oil and a linear hydrocarbon oil in a weight ratio of 99: 1 to 25:75, magnetic rheology fluid.
delete The method of claim 1,
The carrier oil comprises branched hydrocarbon-based oil and linear hydrocarbon-based oil in a weight ratio of 99: 1 to 60:40.
The method of claim 1,
The branched hydrocarbon-based oil comprises a branched poly-alphaolefin, magnetorheological fluid.
The method of claim 1,
The branched hydrocarbon-based oil has a CH content of 5 to 15% by weight of the side chain relative to the total weight of the branched hydrocarbon-based oil, magnetorheological fluid.
The method of claim 1,
The branched hydrocarbon-based oil has a weight average molecular weight of more than 500 g / mol 1500 g / mol or less, magnetorheological fluid.
The method of claim 1,
Wherein said linear hydrocarbon-based oil has a CH content of the side chain less than 5% by weight relative to the total weight of the linear hydrocarbon-based oil.
The method of claim 1,
The linear hydrocarbon oil has a weight average molecular weight of 500 g / mol or less, magnetorheological fluid.
The method of claim 1,
The linear hydrocarbon-based oil comprises a mineral oil, magnetic rheology fluid.
The method of claim 9,
The mineral oil comprises a paraffinic oil having 20 to 40 carbon atoms, magnetorheological fluid.
The method of claim 1,
The magnetic particles include any one or two or more selected from the group consisting of iron powder, carbonyl iron powder, ferrite powder, gas atomized iron powder, and water atomized iron powder.
The method of claim 1,
Wherein the magnetic particles are spherical particles having an average particle size (D ₅₀ ) of 1 μm to 50 μm.
The method of claim 1,
The magnetic particles are surface-treated with any one or two or more materials selected from the group consisting of organic compounds, inorganic oxide fine particles, metals and polymers.
The method of claim 1,
And the magnetic particles are surface treated with silica.
The method of claim 14,
And the silica has an average particle size (D ₅₀ ) of 5 to 100 nm.
The method of claim 14,
The magnetic rheology fluid of the magnetic particles, the surface of the silica at a content of 0.05ppm or more and less than 0.2ppm.
The method of claim 1,
The magnetic rheology fluid content of the magnetic particles is 70% to 100% by weight based on the total weight of the magnetic rheology fluid.
The method of claim 1,
A magnetorheological fluid further comprising at least one dispersant selected from aliphatic alcohols and aliphatic diols.
The method of claim 1,
Viscosity at a temperature of 40 ° C. at a speed of 1 rpm is 15,000 cps or less, viscosity at a speed of 10 rpm is 1,500 cps or less, a thixotropic index of 5 or more, and for 60 days at a temperature of 20 to 30 ° C. and 1 atmosphere Magnetorheological fluid with a redispersion energy of less than 0.3 mJ after storage.

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