Magnetic fluid composition

Abstract

Provided is a magnetic fluid composition which can achieve a high braking force and is not susceptible to the influence of the ambient temperature of the surroundings. The magnetic fluid composition includes metal magnetic particles, non-magnetic particles, and an ionic liquid, in which the ionic liquid includes one or more cationic groups selected from the group consisting of quaternary ammonium ions, imidazolium ions, pyridinium ions, and phosphonium ions, and one or more anionic groups selected from the group consisting of quaternary ammonium ions, imidazolium ions, pyridinium ions, and phosphonium ions. The anionic group is at least one type selected from the group consisting of tetrafluoroboric acid ions, hexafluorophosphoric acid ions, tri-pentafluoroethyl trifluorophosphoric acid ions, and bis (trifluoromethylsulfonyl) amide ions, and the nonmagnetic particles have a volume average particle diameter of more than 10 nm and 800 nm or less.

Description

Technical Field

[0001] The present invention relates to a magnetic fluid composition. Background Art

[0002] Magnetorheological fluid (also known as MR fluid) is a fluid made by dispersing metal magnetic particles in a dispersion medium such as mineral oil or silicone oil. When a magnetic field is applied to the MR fluid, the metal magnetic particles become magnetized and align along the field, forming chain-like clusters, which changes the fluid's viscosity. The strength of these chain-like clusters depends on the magnitude of the applied magnetic field, and by varying the magnetic field, the viscosity can be altered.

[0003] Furthermore, when the magnetic field is removed, the magnetization of the metal magnetic particles is released, and the chain-like clusters return to their original unoriented state, returning the viscosity to their original state. Magnetorheological fluids can adjust their viscosity by repeatedly applying and removing the magnetic field or varying the intensity of the field. Consequently, magnetorheological fluids are being studied for use in a variety of applications, including control devices such as linear and rotary dampers, and braking devices such as brakes and clutches.

[0004] Magnetorheological fluids used in brake systems require high braking force. Furthermore, the temperature range in which they are used is assumed to be between tens of degrees and hundreds of degrees Celsius, requiring them to maintain their physical properties not only at room temperature but also at low and high temperatures.

[0005] For example, Patent Document 1 assumes that a magnetorheological fluid is used at a high temperature of 200° C. and discloses a method of using an ionic liquid in a dispersion medium as a solution for suppressing evaporation of the magnetorheological fluid.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2010-504635.

[0009] As the scope of application of magnetorheological fluids expands, magnetorheological fluids that have a high braking force and are less susceptible to the influence of ambient temperature are sought. Summary of the Invention

[0010] Technical problem to be solved by the invention

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magnetic fluid composition that can achieve a high braking force and is less susceptible to the influence of the surrounding ambient temperature.

[0012] Technical solutions to solve problems

[0013] That is, the present invention includes the following technical solutions.

[0014] [1] A magnetic fluid composition comprising metal magnetic particles, non-magnetic particles, and an ionic liquid, wherein the ionic liquid comprises a cationic group and an anionic group, the cationic group being one or more selected from the group consisting of a quaternary ammonium ion, an imidazolium ion, a pyridinium ion, and a phosphonium ion, and the anionic group being one or more selected from the group consisting of a tetrafluoroborate ion, a hexafluorophosphate ion, a tris-pentafluoroethyl trifluorophosphate ion, and a bis(trifluoromethanesulfonyl)amide ion.

[0015] The non-magnetic particles have a volume average particle size of greater than 10 nm and 800 nm or less.

[0016] [2] The magnetic fluid composition according to [1], wherein the non-magnetic particles are made of an inorganic material.

[0017] [3] The magnetic fluid composition according to [1] or [2], wherein the content ratio of the non-magnetic particles relative to the total amount of the magnetic fluid composition is 0.01 mass % or more and 5 mass % or less.

[0018] [4] The magnetic fluid composition according to any one of [1] to [3], wherein the yield stress of the magnetic fluid composition is 15 kPa or more when a magnetic field of 0.6 Tesla is applied.

[0019] [5] The magnetic fluid composition according to any one of [1] to [4], wherein the boiling point of the magnetic fluid composition is 250°C or higher and the freezing point is 0°C or lower.

[0020] [6] The magnetic fluid composition according to any one of [1] to [5], wherein the cationic group is any one of the following cations (A)-1, (A)-2, (B)-1, (C)-1, and (D)-1.

[0021] [Chemical Formula 1]

[0022]

[0023] [In the above formula, R 21 is an alkyl group having 4 to 6 carbon atoms, R 31 It is an alkyl group having 4 to 8 carbon atoms.]

[0024] Effects of the Invention

[0025] According to the present invention, it is possible to provide a magnetorheological fluid that can achieve a high braking force and is less susceptible to the influence of the ambient temperature. DETAILED DESCRIPTION

[0026] Magnetic fluid composition

[0027] The present invention is a magnetic fluid composition comprising metal magnetic particles, non-magnetic particles and ionic liquid.

[0028] Hereinafter, each component will be described.

[0029] Metal magnetic particles

[0030] The metal magnetic particles herein are particles formed from a paramagnetic metal material. The metal magnetic particles are paramagnetic throughout. The material forming the magnetic particles contains a metal element, preferably at least one metal element selected from the group consisting of Fe, Ni, and Co.

[0031] The above-mentioned metal elements may be contained in the magnetic metal particles as magnetic alloys, magnetic metal oxides, magnetic metal nitrides, or magnetic metal carbides.

[0032] The material constituting the metal magnetic particles may also contain elements other than Fe, Ni and Co. Specific examples include Al, Si, S, Sc, Ti, V, Cu, Y, Mo, Rh, Pd, Ag, Sn, Sb, Te, Ba, Ta, W, Re, Au, Bi, La, Ce, Pr, Nd, P, Zn, Sr, Zr, Mn, Cr, Nb, Pb, Ca, B, C, and N.

[0033] Specific examples of the material constituting the metal magnetic particles include Fe-Co alloys (preferably Permalloy), Fe-Ni alloys (preferably Permalloy), Fe-Zr alloys, Fe-Mn alloys, Fe-Si alloys, Fe-Al alloys, Ni-Mo alloys (preferably superconducting magnetic alloys), Fe-Ni-Co alloys, Fe-Si-Cr alloys, Fe-Si-B alloys, Fe-Si-Al alloys (preferably Sendust soft magnetic alloys), Fe-Si-BC alloys, Fe-Si-B-Cr alloys, Fe-Si-B-Cr-C alloys, Fe-Co-Si-B alloys, Fe-Si-B-Nb alloys, Fe nanocrystalline alloys, Fe-based amorphous alloys and Co-based amorphous alloys, as well as ferrites such as spinel ferrites (preferably Ni-Zn ferrites or Mn-Zn ferrites) and hexagonal ferrites (preferably barium ferrites).

[0034] The above alloys may also be amorphous alloys.

[0035] Among them, amorphous alloys are preferred, and Fe-Si-B-Cr-C alloys, Fe-based amorphous alloys, Fe-Si-Cr alloys, Fe nanocrystalline alloys, Fe-Ni-Co alloys, Co-based amorphous alloys, and Ni-Mo alloys are more preferred.

[0036] The materials constituting the metal magnetic particles may be used alone or in combination of two or more.

[0037] The content ratio of the metal magnetic particles in the magnetic fluid composition is, for example, 10 mass % to 99 mass % or more, or 20 mass % to 90 mass % or less, relative to the total mass of the magnetic fluid composition.

[0038] When two or more types of metal magnetic particles are included, the above-mentioned content ratio refers to the total content ratio of the two or more types of metal composite particles.

[0039] Non-magnetic particles

[0040] A typical magnetic fluid composition comprises metal magnetic particles dispersed in a dispersion medium such as mineral oil or silicone oil.

[0041] Due to the significant difference in specific gravity between common dispersion media such as mineral oil or silicone oil and the metal magnetic particles in the magnetic fluid composition, the metal magnetic particles tend to settle. The settled metal magnetic particles tend to aggregate, separating them from the dispersion medium. When the metal magnetic particles settle and separate, the required yield stress cannot be achieved, resulting in reduced braking force.

[0042] Small particles in a liquid diffuse in a dispersion medium through random Brownian motion. Furthermore, although small particles in a dispersion medium settle due to gravity, the diffusion effect of Brownian motion is greater than the sedimentation velocity of the particles, so that the small particles do not settle and can remain diffused.

[0043] Non-magnetic particles with a volume average particle size greater than 10 nm and less than 800 nm are less likely to settle in the dispersion medium due to Brownian motion and tend to remain dispersed. The diffused non-magnetic particles hinder the settling of the metal magnetic particles, allowing the metal magnetic particles to remain dispersed.

[0044] The volume average particle size of the non-magnetic particles is preferably 12 nm or more and 600 nm or less, and more preferably 14 nm or more and 550 nm or less.

[0045] When the volume average particle size of the non-magnetic particles is equal to or smaller than the upper limit, the diffusion effect of the Brownian motion is made greater than the sedimentation velocity of the particles, and the diffusion state of the non-magnetic particles is maintained.

[0046] When the volume average particle size of the non-magnetic particles is equal to or larger than the above lower limit, the sedimentation of the metal magnetic particles is easily inhibited.

[0047] The sedimentation suppression effect of the metal magnetic particles by the non-magnetic particles is exerted according to the volume average particle size. Therefore, the material is not particularly limited, but non-magnetic inorganic materials, thermoplastic resins, and thermosetting resins can be used.

[0048] Examples of the non-magnetic inorganic material include non-magnetic metals (e.g., gold, silver, copper, palladium, platinum), ceramics (e.g., metal oxides, metal nitrides, metal carbides, metal carbonates, metal halides, metal phosphates, metal sulfates), carbon black, and graphite.

[0049] Examples of metal oxides include aluminum oxide, silicon dioxide, titanium oxide, zinc oxide, calcium oxide, magnesium oxide, tin dioxide, silicon dioxide, non-magnetic chromium oxide, cerium oxide, and non-magnetic iron oxide. Examples of metal carbides include silicon carbide, molybdenum carbide, boron carbide, tungsten carbide, and titanium carbide. Examples of metal carbonates include magnesium carbonate and calcium carbonate.

[0050] Examples of the metal nitride include boron nitride and silicon nitride.

[0051] Examples of the metal halide include calcium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, and lithium chloride.

[0052] Examples of the metal sulfate include barium sulfate and calcium sulfate.

[0053] Examples of the thermoplastic resin include polyester resins, vinyl resins (acrylic resins, polystyrene resins, polyvinyl acetate resins, polyvinyl chloride resins, and the like), ABS resins, and AS resins.

[0054] Examples of the thermosetting resin include phenol resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, and alkyd resins.

[0055] The content of the non-magnetic particles relative to the total amount of the magnetic fluid composition is preferably 0.01 mass % to 5 mass %, more preferably 0.1 mass % to 3 mass %, and even more preferably 0.5 mass % to 2 mass %.

[0056] When the content ratio of the non-magnetic particles is equal to or greater than the above lower limit, the sedimentation of the metal magnetic particles is likely to be inhibited.

[0057] When the content ratio of the non-magnetic particles is equal to or less than the above lower limit, the dispersed state of the non-magnetic particles can be easily maintained.

[0058] Ionic liquids

[0059] The magnetic fluid composition contains an ionic liquid as a dispersion medium.

[0060] Ionic liquids contain cationic groups and anionic groups.

[0061] The cationic group is one or more selected from the group consisting of a quaternary ammonium ion, an imidazolium ion, a pyridinium ion, and a phosphonium ion.

[0062] The anion group is one or more selected from the group consisting of tetrafluoroborate ion, hexafluorophosphate ion, tris-pentafluoroethyltrifluorophosphate ion, and bis(trifluoromethanesulfonyl)amide ion.

[0063] It was found that the ionic liquid having the above-mentioned combination of cationic groups and anionic groups does not evaporate even at 250°C or higher and remains in a liquid state even at 0°C or lower.

[0064] In addition, ionic liquids have a higher affinity for metal magnetic particles than mineral oils, and by using ionic liquids as dispersion media, the magnetic fluid composition is less likely to separate.

[0065] The cationic group and the anionic group are explained below.

[0066] Quaternary ammonium ions

[0067] Examples of the quaternary ammonium ion include cations represented by the following formula (A).

[0068] [Chemical Formula 2]

[0069]

[0070] [In formula (A), R 11 ~R 14 Each of R is independently a linear or branched alkyl group having 1 to 20 carbon atoms. 11 ~R 14 They may also be bonded to each other to form a ring.]

[0071] As R 11 ~R 14 Examples of the linear alkyl group include alkyl groups having 1 to 20 carbon atoms. Specifically, the linear alkyl group includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl.

[0072] As R 11 ~R 14Examples of the branched alkyl group include alkyl groups having 3 to 20 carbon atoms. Specifically, 1-methylethyl, 1-methylpropyl, 2-methylpropyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, and 4-methylpentyl can be mentioned.

[0073] In R 11 ~R 14 When they are bonded to each other to form a ring, examples of the formed ring include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, and cyclododecyl.

[0074] Specific examples of the quaternary ammonium ion include tetraethylammonium, tetramethylammonium, tetrapropylammonium, tetrabutylammonium, and tetrapentylammonium.

[0075] As the quaternary ammonium ion, a cation represented by the following (A)-1 or (A)-2 is more preferable.

[0076] [Chemical Formula 3]

[0077]

[0078] Imidazolium ion

[0079] Examples of the imidazolium ion include cations represented by the following formula (B).

[0080] [Chemical Formula 4]

[0081]

[0082] [In formula (B), R 20 It is a linear or branched alkyl group having 1 to 20 carbon atoms.]

[0083] Regarding R in formula (B) 20 The description of the linear or branched alkyl group having 1 to 20 carbon atoms is the same as that of R in the above formula (A). 11 ~R 14 The same applies to the description of the linear or branched alkyl group having 1 to 20 carbon atoms.

[0084] As R 20 , preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 2 to 8 carbon atoms.

[0085] As the imidazolium ion, a cation represented by the following formula (B)-1 is more preferred.

[0086] [Chemical Formula 5]

[0087]

[0088] [In formula (B)-1, R 21 It is an alkyl group having 4 to 8 carbon atoms.]

[0089] R 21 Examples thereof include n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, and octyl.

[0090] Pyridinium ion

[0091] Examples of the pyridinium ion include cations represented by the following formula (C).

[0092] [Chemical Formula 6]

[0093]

[0094] [In formula (C), R 30 It is a linear or branched alkyl group having 1 to 20 carbon atoms.]

[0095] Regarding R in formula (C) 30 The description of the linear or branched alkyl group having 1 to 20 carbon atoms is the same as that of R in the above formula (A). 11 ~R 14 The same applies to the description of the linear or branched alkyl group having 1 to 20 carbon atoms.

[0096] As R 30 , preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 2 to 8 carbon atoms.

[0097] As the pyridinium ion, a cation represented by the following formula (C)-1 is preferable.

[0098] [Chemical Formula 7]

[0099]

[0100] [In formula (C)-1, R 31 It is an alkyl group having 4 to 6 carbon atoms.]

[0101] R 31 Examples thereof include n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl and hexyl.

[0102] Phosphonium ion

[0103] Examples of the phosphonium ion include cations represented by the following formula (D).

[0104] [Chemical Formula 8]

[0105]

[0106] [In formula (D), R 41 ~R 44 Each of R is independently a linear or branched alkyl group having 1 to 20 carbon atoms. 41 ~R 44 They may also be bonded to each other to form a ring.]

[0107] Regarding R in formula (D) 41 ~R 44 The description of the linear or branched alkyl group having 1 to 20 carbon atoms is the same as that of R in the above formula (A). 11 ~R 14 The same applies to the description of the linear or branched alkyl group having 1 to 20 carbon atoms.

[0108] R 41 ~R 44 An alkyl group having 2 to 18 carbon atoms is preferred, and an alkyl group having 4 to 16 carbon atoms is more preferred.

[0109] Examples of the phosphonium ion include tetrabutylphosphonium, tetrapropylphosphonium, tetraethylphosphonium, tetramethylphosphonium, and hexadecyltributylphosphonium.

[0110] The cation is preferably any one of the following cations (A)-1, (A)-2, (B)-1, (C)-1, and (D)-1.

[0111] [Chemical Formula 9]

[0112]

[0113] [In the above formula, R 21 is an alkyl group having 4 to 6 carbon atoms, R 31 It is an alkyl group having 4 to 8 carbon atoms.]

[0114] The anion group is one or more selected from the group consisting of tetrafluoroborate ion, hexafluorophosphate ion, tris-pentafluoroethyltrifluorophosphate ion, and bis(trifluoromethanesulfonyl)amide ion.

[0115] The above-mentioned cationic groups and anionic groups are both large-volume ions. According to the research of the present inventors, it was found that the ionic liquid composed of the above-mentioned large-volume ions is not easy to evaporate even at high temperatures and is easy to maintain a liquid state even at low temperatures when used as a magnetic fluid composition for the dispersion medium.

[0116] While the dispersion medium is preferably composed of an ionic liquid, the dispersion medium may contain additives other than the ionic liquid within the scope that does not affect the effects of the present invention. Examples of such additives include thixotropic agents, surfactants, viscoplastic media, and water-in-oil emulsions.

[0117] The content ratio of the ionic liquid relative to the total amount of the magnetic fluid composition is preferably 5% by mass or more and 30% by mass or less, and more preferably 10% by mass or more and 20% by mass or less.

[0118] When the content ratio of the ionic liquid is within the above range, the dispersed state of the non-magnetic particles can be easily maintained.

[0119] Physical properties of magnetic fluid compositions

[0120] The yield stress of the magnetic fluid composition is preferably 15 kPa or more, more preferably 20 kPa or more, under an applied magnetic field of 0.6 Tesla. The yield stress of the magnetic fluid composition can be measured by the method described in the Examples.

[0121] The boiling point of the magnetic fluid composition is preferably 250° C. or higher, more preferably 300° C. or higher, and even more preferably 350° C. or higher. The boiling point of the magnetic fluid composition can be measured by the method described in the Examples.

[0122] The freezing point of the magnetic fluid composition is preferably 0° C. or lower, more preferably -10° C. or lower, and further preferably -20° C. or lower. The freezing point of the magnetic fluid composition can be measured by the method described in the Examples.

[0123] Method for producing magnetic fluid composition

[0124] The magnetic fluid composition of the present embodiment can be produced by mixing and stirring metal magnetic particles, non-magnetic particles, and an ionic liquid at a desired ratio.

[0125] Example

[0126] Production of magnetic fluid compositions

[0127] The metal magnetic particles, non-magnetic particles, and ionic liquids shown in Tables 1 to 6 were mixed at the following ratios and stirred under the following conditions to produce magnetic fluid compositions of Examples 1 to 22 and Comparative Examples 1 to 12, respectively.

[0128] Mixing ratio

[0129] Metal magnetic particles: 80% by mass

[0130] Non-magnetic particles: 1% by mass

[0131] Ionic liquid: 19% by mass

[0132] Stirring conditions

[0133] The mixture was stirred at 3000 rpm for 30 minutes using a high shear mixer (Silverson, L5M-A).

[0134] The boiling point, freezing point, and yield stress of the magnetic fluid composition were measured and evaluated by the following methods.

[0135] boiling point

[0136] 2 mL of the magnetic fluid composition was heated on a hot plate, and the temperature at which white smoke was generated was confirmed and evaluated according to the following criteria: In the following criteria, a score of A or B was evaluated as "the boiling point of the magnetic fluid composition is high."

[0137] A: No evaporation until 350℃

[0138] B: No evaporation until 250°C

[0139] C: Evaporation below 250℃

[0140] Freezing point

[0141] 2 mL of the magnetic fluid composition was cooled in a refrigerator, the temperature after solidification was confirmed, and evaluation was performed based on the following criteria: In the following criteria, a score of A or B was evaluated as "the magnetic fluid composition has a low freezing point."

[0142] A: Solidify below -20℃

[0143] B: Solidifies at temperatures above -20°C and below 0°C

[0144] C: Solidifies at temperatures above 0°C and below 10°C

[0145] Yield stress

[0146] The yield stress of the magnetic fluid composition was measured at 250°C under a shear stress of 333 Å / sec and a magnetic field of 0.6 Tesla, and evaluated according to the following criteria. A rating of A or B in the following criteria was considered "high braking force of the magnetic fluid composition."

[0147] A: More than 20kPa

[0148] B: 15kPa or more and less than 20kPa

[0149] C: 10kPa or more and less than 15kPa

[0150] [Table 1]

[0151]

[0152] [Table 2]

[0153]

[0154] [Table 3]

[0155]

[0156] [Table 4]

[0157]

[0158] [Table 5]

[0159]

[0160] [Table 6]

[0161]

[0162] The structures of the cations in Tables 1 to 6 are shown below.

[0163] [Chemical Formula 10]

[0164]

[0165] As shown in the above results, the yield stresses in Examples 1-22 were all A or B, confirming that they could achieve high braking force. Furthermore, the boiling point and freezing point results in Examples 1-22 were all A or B, confirming that they were less likely to evaporate at high temperatures and less likely to solidify at low temperatures. Therefore, it was confirmed that the magnetic fluid compositions of Examples 1-22 were able to achieve high braking force and were not easily affected by the ambient temperature.

[0166] In Comparative Example 1, in which hydrocarbon oil was used as the dispersion medium instead of an ionic liquid, the affinity between the metal magnetic particles and the dispersion medium was insufficient, and it is considered that the yield stress was insufficient due to separation of the magnetic fluid composition.

[0167] Comparative Example 2 containing no non-magnetic particles and Comparative Examples 3 to 5 having non-magnetic particles whose particle sizes did not satisfy the present invention caused the metal magnetic particles to settle, and it is thought that the yield stress was insufficient due to separation of the magnetic fluid composition.

[0168] In Comparative Examples 6 to 8 using polymers with low heat resistance as non-magnetic particles, the polymers melted due to heating during yield stress measurement, causing the metal magnetic particles to precipitate. This is thought to be due to separation of the magnetic fluid composition, resulting in insufficient yield stress.

[0169] In Comparative Examples 9 to 12, in which ionic liquids containing small anionic groups were used, it was confirmed that the freezing points were high and the liquids were easily solidified at low temperatures.

Claims

1. A magnetic fluid composition, characterized in that Contains metal magnetic particles, non-magnetic particles and ionic liquid, The ionic liquid comprises a cationic group and an anionic group, The cationic group is one or more selected from the group consisting of quaternary ammonium ions, imidazolium ions, pyridinium ions and phosphonium ions, The anionic group is one or more selected from the group consisting of tetrafluoroborate ion, hexafluorophosphate ion, tris-pentafluoroethyl trifluorophosphate ion and bis(trifluoromethanesulfonyl)amide ion, The non-magnetic particles have a volume average particle size of greater than 10 nm and 800 nm or less.

2. The magnetic fluid composition according to claim 1, characterized in that The non-magnetic particles are inorganic materials.

3. The magnetic fluid composition according to claim 1 or 2, characterized in that The content ratio of the non-magnetic particles relative to the total amount of the magnetic fluid composition is 0.01 mass % or more and 5 mass % or less.

4. The magnetic fluid composition according to claim 1 or 2, characterized in that The yield stress of the magnetic fluid composition is 15 kPa or more in a state where a magnetic field of 0.6 Tesla is applied.

5. The magnetic fluid composition according to claim 1 or 2, characterized in that The magnetic fluid composition has a boiling point of 250° C. or higher and a freezing point of 0° C. or lower.

6. The magnetic fluid composition according to claim 1 or 2, characterized in that The cationic group is any one of the following cations (A)-1, (A)-2, (B)-1, (C)-1, and (D)-1, In the above formula, R 21 is an alkyl group having 4 to 6 carbon atoms, R 31 It is an alkyl group having 4 to 8 carbon atoms.

Images