Method for Obtaining Dispersions and Dispersions

Abstract

To provide a dispersion element obtained by dispersing sodium into a solvent having a boiling point lower than a melting point of the sodium, and a method for obtaining the same.SOLUTION: A method for obtaining a dispersion element has a step of at least partially replacing mineral oil of a first dispersion element obtained by dispersing sodium into the mineral oil with a non-polar solvent having a boiling point of 97°C or lower to obtain a second dispersion element in which the sodium is dispersed into a dispersion solvent containing the non-polar solvent. As unit operations, the method includes: a centrifugal separation operation of subjecting a sample to centrifugal separation; a removal operation of at least partially removing an upper layer from the sample after the centrifugal separation operation; and an addition operation of adding the dispersion solvent to the sample after the removal operation. The method includes a step of executing the centrifugal separation operation, the removal operation and the addition operation plural times using the first dispersion element as a starting sample and using the non-polar solvent as the dispersion solvent in the addition operation to thereby obtain the second dispersion element.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for obtaining a dispersion in which sodium is dispersed in a dispersion solvent, and to the dispersion. [Background technology]

[0002] Conventionally, metallic sodium has been useful as a metal exchange reagent, a nucleophile, a strong base, and the like, but must be handled with care because it reacts violently with water, oxygen, etc. Dispersions in which metallic sodium is dispersed in organic solvents have conventionally been used as a form in which metallic sodium can be used favorably.

[0003] For example, Japanese Patent Laid-Open No. 10-110205 (Patent Document 1) discloses a metallic sodium dispersion in which sodium is dispersed in transformer oil, and Japanese Patent Laid-Open No. 2001-234208 (Patent Document 2) discloses a sodium dispersion in which sodium is dispersed in oil such as transformer oil or liquid paraffin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-110205 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-234208 Summary of the Invention [Problem to be solved by the invention]

[0005] In the techniques of Patent Documents 1 and 2, the dispersion solvent for dispersing sodium was essentially limited to solvents (such as transformer oil and liquid paraffin) that had a boiling point higher than the melting point of sodium (97.72°C) and a relatively high viscosity. This is related to the fact that when micronizing and dispersing sodium, a process of applying mechanical shear force at a temperature higher than the melting point of sodium is commonly used. In other words, it is advantageous to use as the dispersion solvent a solvent that is liquid under the temperature conditions of the above process and has a relatively high viscosity that can apply shear force to the sodium droplets, and the above-mentioned examples of transformer oil and liquid paraffin are preferably used as solvents that meet this condition.

[0006] However, depending on the application of the sodium dispersion, it may be required to supply the sodium in a form in which the sodium is dispersed in a dispersion solvent other than the solvents exemplified above. In particular, there is a need for a dispersion in which sodium is dispersed in a solvent having a boiling point lower than the melting point of sodium, and a method for obtaining the same. [Means for solving the problem]

[0007] The method according to the present invention is a method for at least partially replacing the mineral oil of a first dispersion in which sodium is dispersed in mineral oil with a non-polar solvent having a boiling point of 97°C or less, to obtain a second dispersion in which sodium is dispersed in a dispersion solvent containing the non-polar solvent, the method comprising, as unit operations, a centrifugation operation of subjecting a sample to centrifugation, a removal operation of at least partially removing an upper layer from the sample after the centrifugation operation, and an addition operation of adding a dispersion solvent to the sample after the removal operation, and comprising using the first dispersion as a starting sample and performing the centrifugation operation, the removal operation, and the addition operation multiple times to obtain the second dispersion. In the first centrifugation operation, the product of the centrifugal acceleration (unit: G) and the duration (unit: minutes) is set to 25,000 G·min or more and 84,000 G·min or less. It is characterized by:

[0008] According to this configuration, a dispersion (second dispersion) in which sodium is dispersed in a nonpolar solvent having a boiling point of 97°C or less can be obtained using a conventional dispersion (first dispersion) in which sodium is dispersed in mineral oil as a starting material. Although centrifuging a sodium dispersion has not been common in the past, the inventors' extensive research has revealed that the dispersion solvent can be easily replaced by using centrifugation. Furthermore, since the dispersion solvent is replaced by repeating unit operations including centrifugation, removal, and addition, a dispersion (second dispersion) is obtained in which a certain amount of mineral oil, the dispersion solvent in the starting material (first dispersion), remains. This makes it possible to obtain a dispersion (second dispersion) in which a stable dispersion state of sodium is maintained, even though the main dispersion solvent is a nonpolar solvent having a boiling point of 97°C or less, which has a lower boiling point and viscosity than the dispersion solvent used in conventional sodium dispersions. In particular, by setting the product of the centrifugal acceleration (unit: G) and the duration (unit: minutes) in the first centrifugation operation to between 25,000 G·min and 84,000 G·min, the mineral oil and sodium are easily separated, and excessive heating of the sample due to centrifugation and aggregation of the sodium dispersed in the mineral oil can be suppressed.

[0009] The dispersion according to the present invention is The method comprises, as unit operations, a centrifugation operation of centrifuging a sample, a removal operation of at least partially removing an upper layer from the sample after the centrifugation operation, and an addition operation of adding a dispersion solvent to the sample after the removal operation, wherein a first dispersion in which sodium is dispersed in mineral oil is used as a starting sample, and a non-polar solvent having a boiling point of 97°C or less is used as the dispersion solvent in the addition operation, and the centrifugation operation, the removal operation, and the addition operation are carried out multiple times to obtain a dispersion in which sodium is dispersed in a dispersion solvent containing the non-polar solvent, and the method is produced by a method in which the product of the centrifugal acceleration (unit: G) and the duration (unit: minute) in the first centrifugation operation is 25,000 G·min or more and 84,000 G·min or less. A dispersion in which sodium is dispersed in a dispersion solvent, characterized in that the dispersion solvent contains a mineral oil and a non-polar solvent having a boiling point of 97°C or less, and the content of the mineral oil is 1% by mass or more and 50% by mass or less.

[0010] This configuration makes it possible to realize a dispersion in which sodium is maintained in a stable dispersed state while using a non-polar solvent with a boiling point of 97°C or less as the main dispersion solvent, which has a lower boiling point and viscosity than the dispersion solvents used in conventional sodium dispersions.

[0011] Preferred embodiments of the present invention will be described below, but the scope of the present invention is not limited to the preferred embodiments described below.

[0012] In one embodiment of the method of the present invention, the product of the centrifugal acceleration (unit: G) and the duration (unit: min) in the second or subsequent centrifugation operation is preferably smaller than the product of the centrifugal acceleration (unit: G) and the duration (unit: min) in the first centrifugation operation.

[0013] According to this configuration, since the viscosity of the dispersion solvent differs between the first centrifugation operation and the second and subsequent centrifugation operations, the mineral oil can be efficiently separated while applying centrifugation conditions suitable for each centrifugation operation. In the first centrifugation operation, since the dispersion solvent is a mineral oil with a relatively high viscosity, the product of centrifugal acceleration and duration is set relatively large. In contrast, in the second and subsequent centrifugation operations, since the viscosity of the dispersion solvent is lower than that of the mineral oil, centrifugation is performed under milder conditions than the first centrifugation operation, i.e., conditions with a smaller product of centrifugal acceleration and duration.

[0016] In one aspect of the method according to the present invention, it is preferable that the product of the centrifugal acceleration (unit: G) and the duration (unit: minute) in the second or subsequent centrifugation operation is 1200 G·min or more and 25000 G·min or less.

[0017] This configuration facilitates sufficient separation of the mineral oil and sodium, and can prevent excessive temperature rise of the sample due to centrifugation and aggregation of sodium dispersed in the mineral oil.

[0018] According to the above configuration, the conditions of the duration and angular velocity of the centrifugal separation operation that will sufficiently separate the mineral oil and the sodium can be clearly specified.

[0019] In one embodiment, the method according to the present invention preferably further comprises specifying the proportions of sodium, the mineral oil, and the non-polar solvent contained in the second dispersion.

[0020] According to this configuration, the composition of the obtained second dispersion can be specified, and the composition can be taken into consideration when using the second dispersion. Furthermore, the composition of the second dispersion can be adjusted based on the specified composition. DETAILED DESCRIPTION OF THE INVENTION

[0021] The method and dispersion according to the present invention will be described with reference to the drawings. In the following, an example will be described in which the method according to the present invention is applied to a method for at least partially replacing the mineral oil of a first dispersion in which sodium is dispersed in mineral oil with hexane (an example of a non-polar solvent having a boiling point of 97°C or less) to obtain a second dispersion in which sodium is dispersed in a dispersion solvent containing hexane.

[0022] [Configuration of Dispersion Body] A dispersion in which sodium is dispersed in a dispersion solvent (hereinafter referred to as SD (Sodium Dispersion)) is one in which sodium is dispersed as fine particles (i.e., solid) in a dispersion solvent, or one in which sodium is dispersed as fine droplets (i.e., liquid) in a dispersion solvent. Here, the sodium may be pure metallic sodium or an alloy containing metallic sodium. In the following, the first dispersion will be referred to as the first SD, and the second dispersion will be referred to as the second SD.

[0023] The average particle size of sodium (fine particles or droplets) in SD is preferably less than 100 μm, more preferably less than 50 μm, even more preferably less than 30 μm, even more preferably less than 10 μm, and particularly preferably less than 5 μm. The average particle size is expressed as the diameter (equivalent diameter) of a sphere having the same projected area as the projected area obtained by image analysis of a micrograph.

[0024] The sodium content in SD is preferably 10% by mass or more and 30% by mass or more, and more preferably 15% by mass or more and 25% by mass or more. The sodium content may be calculated from the mass ratio of sodium to the dispersion solvent used in producing the SD, or may be determined by a method in which the obtained SD is added to an excess amount of water to form an aqueous sodium hydroxide solution, and the amount of sodium in the SD is determined based on the concentration of the aqueous sodium hydroxide solution determined by neutralization titration.

[0025] Generally, any known solvent can be used as the dispersion solvent in SD, as long as it can disperse sodium (fine particles or droplets). Examples of such solvents include paraffinic solvents (normal paraffinic solvents, cycloparaffinic solvents), aromatic solvents, and heterocyclic solvents. Examples of normal paraffinic solvents include, but are not limited to, normal pentane, normal hexane, normal heptane, normal octane, normal nonane, and normal decane. Examples of cycloparaffinic solvents include, but are not limited to, cyclopentane. Examples of ether solvents include, but are not limited to, tetrahydrofuran, cyclopentyl methyl ether, and 2-methyltetrahydropyrene. Examples of aromatic solvents include, but are not limited to, benzene, toluene, and xylene. Examples of amine solvents include, but are not limited to, ethylenediamine. Examples of heterocyclic solvents include, but are not limited to, tetrahydrothiophene. These solvents may be used alone or in the form of a mixed solvent of two or more kinds. A typical mixed solvent is mineral oil.

[0026] [Method for producing dispersion] As a specific method for producing SD, known methods can be adopted. For example, JP 2007-197787 A discloses a method in which metallic sodium (liquid) heated to a temperature equal to or higher than the melting point and a paraffinic solvent are mixed sequentially in a primary dispersion device and a secondary dispersion device.

[0027] The primary dispersion device can be, for example, a stirrer equipped with paddle blades or disk turbine blades, and the stirrer is provided with a jacket through which synthetic heat transfer oil can be circulated. The stirrer is operated with synthetic heat transfer oil at 105 to 140°C circulating through the jacket, to obtain a primary dispersion in which sodium is dispersed in a paraffin-based solvent. The average particle size of sodium in the primary dispersion is, for example, 20 μm or less.

[0028] The secondary dispersion device may be, for example, a device having a rotor and a stator. Both the rotor and the stator are provided with blades, and as the rotor rotates, a shear force is generated between the rotor blades and the stator blades, which is applied to the object to be treated. When the primary dispersion is supplied to the secondary dispersion device and the secondary dispersion device is operated, a secondary dispersion in which the dispersed particle size of sodium is smaller than that of the primary dispersion is obtained. This secondary dispersion is used as the SD.

[0029] In conventional methods for producing SD, as seen in the above example, temperatures higher than the melting point of sodium (97.72°C) may be used. This is because sodium microparticles can be obtained by mixing sodium heated above its melting point with a dispersion solvent. In other words, from the perspective of ensuring stable existence as SD, there are no limitations on the dispersion solvent as long as it is a solvent that can disperse sodium. However, from the perspective of facilitating the production of SD, it is preferable to use a solvent with a boiling point higher than the melting point of sodium as the dispersion solvent. Conversely, it has traditionally been difficult to produce SD using a dispersion solvent with a boiling point lower than the melting point of sodium.

[0030] [Method for Obtaining Second Dispersion] The following describes a method for obtaining a second SD from a first SD obtained using a mineral oil as a dispersion solvent in a known method such as those described above. The method according to this embodiment includes, as unit operations, a centrifugation operation, a removal operation, and an addition operation, and these unit operations are repeated multiple times to obtain a second dispersion.

[0031] (1) Centrifugal separation Centrifugation is a procedure in which a sample is centrifuged. The sample used in the first centrifugation is the first SD, and in the second and subsequent centrifugation procedures, it is SD in which sodium is dispersed in a mixed solvent of mineral oil and hexane (SD obtained after the addition procedure described below). When the SD is centrifuged, an upper layer consisting mainly of the dispersion solvent and a lower layer consisting mainly of sodium are formed.

[0032] In the first centrifugation operation, the centrifugal acceleration is preferably 1200 G or more and 2500 G or less. By setting the centrifugal acceleration to 1200 G or more, sufficient separation of the mineral oil and sodium is likely to be achieved. Furthermore, by setting the centrifugal acceleration to 2500 G or less, excessive temperature rise of the SD due to centrifugation and aggregation of sodium dispersed in the mineral oil can be suppressed. The centrifugal acceleration in the first centrifugation operation is more preferably 1300 G or more, and even more preferably 1400 G or more. Furthermore, the centrifugal acceleration is more preferably 1900 G or less, and even more preferably 1800 G or less.

[0033] The duration of the first centrifugation operation is preferably 5 minutes or more and 60 minutes or less. By setting the duration to 5 minutes or more, sufficient separation of the mineral oil and sodium is likely to be achieved. Furthermore, by setting the duration to 60 minutes or less, excessive temperature rise of the SD due to centrifugation and aggregation of sodium dispersed in the mineral oil can be suppressed. The duration of the first centrifugation operation is more preferably 20 minutes or more, and even more preferably 25 minutes or more. Furthermore, the duration is more preferably 40 minutes or less, and even more preferably 35 minutes or less.

[0034] In the second or subsequent centrifugation operations, the centrifugal acceleration is preferably set to 1200 G or more and 2500 G or less. By setting the centrifugal acceleration to 1200 G or more, sufficient separation of the dispersion solvent and sodium is easily achieved. Furthermore, by setting the centrifugal acceleration to 2500 G or less, excessive temperature rise of the SD due to centrifugation and aggregation of sodium dispersed in the dispersion solvent can be suppressed. The centrifugal acceleration in the second centrifugation operation is more preferably set to 1300 G or more, and even more preferably set to 1400 G or more. Furthermore, the centrifugal acceleration is more preferably set to 1900 G or less, and even more preferably set to 1800 G or less.

[0035] The duration of the second or subsequent centrifugation operation is preferably 1 minute or more and 10 minutes or less. By setting the duration to 1 minute or more, sufficient separation of the dispersion solvent and sodium is likely to be achieved. Furthermore, by setting the duration to 10 minutes or less, excessive temperature rise of the SD due to centrifugation and aggregation of sodium dispersed in the dispersion solvent can be suppressed. The duration of the second centrifugation operation is more preferably 2 minutes or more, and even more preferably 3 minutes or more. Furthermore, the duration is more preferably 8 minutes or less, and even more preferably 7 minutes or less.

[0036] In the second and subsequent centrifugation operations, part of the dispersion solvent is replaced with hexane from mineral oil, so the boiling point of the dispersion solvent is lower than the boiling point of the dispersion solvent (mineral oil) in the first centrifugation operation. Therefore, in the second and subsequent centrifugation operations, it is necessary to further suppress the temperature rise. In view of this, the upper limit of the suitable duration for the second and subsequent centrifugation operations is smaller than the upper limit of the suitable duration for the first centrifugation operation.

[0037] Furthermore, in the centrifugation operation, it is preferable that the centrifugation is carried out under conditions where the settling time T (unit: minutes) and the angular velocity ω (unit: radians / second) satisfy the formula (1) within a predetermined range of particle diameter d.

number

[0038] In formula (1), R max is the maximum radius of rotation of the sample subjected to centrifugation (unit: m), and R min is the minimum radius of rotation of the sample (in m). More specifically, R max is determined by the diameter of the rotor of the centrifuge used in the centrifugation operation. minis determined by the diameter of the rotor of the centrifuge used in the centrifugation operation, the dimensions of the sample tube used in the centrifugation operation, and the liquid level of the sample in the sample tube. Note that information on the dimensions of the device to be used, such as the diameter of the rotor of the centrifuge and the dimensions of the sample tube, can usually be easily obtained from the instruction manual of the centrifuge.

[0039] Also, S is the Spedberg unit (seconds) expressed by equation (2).

number

[0040] The predetermined particle diameter d varies depending on the number of centrifugation operations. For the first centrifugation operation, the predetermined particle diameter d may be 1.6 μm or more and 4.3 μm or less. For the second centrifugation operation, the predetermined particle diameter d may be 1.25 μm or more and 3.30 μm or less. For the third and subsequent centrifugation operations, the predetermined particle diameter d may be 0.32 μm or more and 0.90 μm or less. This is because, in the method according to this embodiment, the proportion of hexane in the dispersion solvent increases with each centrifugation operation, causing the viscosity of the dispersion solvent to decrease. Therefore, the predetermined particle diameter d that should be considered when determining the centrifugation conditions varies depending on the number of centrifugation operations. For the first centrifugation operation, the predetermined particle diameter d is more preferably 1.8 μm or more and 3.0 μm or less. For the second centrifugation operation, the predetermined particle diameter d is more preferably 2.0 μm or more and 2.5 μm or less. For the third and subsequent centrifugation operations, the predetermined particle diameter d is more preferably 0.5 μm or more and 0.8 μm or less. By substituting the values ​​in the above particle size range into equation (2) to determine the value of the Spedberg unit S, and then performing centrifugation for the settling time T calculated using equation (1) using that value of the Spedberg unit S, it is possible to efficiently separate the sodium particles and the dispersion medium. If the centrifugation is performed for the settling time T calculated using a value greater than the upper limit of the above particle size range, the sodium particles may remain in the liquid portion, making efficient separation impossible. Furthermore, if the centrifugation is performed for the settling time T calculated using a value smaller than the lower limit of the above particle size range, the sodium particles may aggregate and form clumps, making separation impossible.

[0041] A simpler method for specifying the preferable centrifugation conditions that satisfy the above formulas (1) and (2) may be to use a method that uses the product of the centrifugal acceleration (unit: G) and the sedimentation time (unit: minutes) as an index. C is given by the following equation (3).

number

[0042] In formula (3), R maxis the maximum radius of rotation of the sample subjected to centrifugation (unit: m), ω is the angular velocity (unit: radians / second), and g is the gravitational acceleration (unit: m / second). 2 In equation (3), R max As is clear from the above, the centrifugal acceleration in question here is, more accurately, the centrifugal acceleration at the point where the maximum radius of rotation of the sample is the largest, that is, the centrifugal acceleration at the bottom of the sample tube used during the centrifugation operation.

[0043] By transforming equation (3), we obtain the following equation (3-1).

number

[0044] Substituting equation (3-1) into equation (1) and rearranging it, we obtain the following equation (1-1).

number

[0045] In equation (1-1), the right-hand side is a function of variables dependent on the specifications of the centrifuge, variables dependent on the type of dispersion solvent, and the particle size of sodium. The specifications of the centrifuge are determined when the centrifuge to be used is selected, and the type of dispersion solvent is determined according to the requirements of the final dispersion to be obtained, so the variables dependent on these have essentially no flexibility. Therefore, a correlation is observed between the value of the left-hand side (the product of centrifugal acceleration and sedimentation time) and the particle size range of the sedimenting particles.

[0046] After extensive research, the inventors discovered that the product of centrifugal acceleration and duration (when setting centrifugation conditions, the sedimentation time T in Equation (1) and other formulas is understood as "duration") in the first centrifugation operation is preferably 25,000 G·min or more and 84,000 G·min or less. When this product is within the above range, sodium in the sample precipitates and sodium redispersion is easy. It is more preferable that this product is 36,000 G·min or more. Furthermore, it is more preferable that this product is 72,000 G·min or less. When setting a combination of centrifugal acceleration and duration that satisfies the above range, a duration of 60 minutes or less is economically advantageous because the time required for the centrifugation operation is relatively short. Furthermore, a centrifugal acceleration of 5,400 G or less is easily achieved using commonly available centrifuge equipment.

[0047] The inventors also discovered that for the second or subsequent centrifugation operation, the product of centrifugal acceleration and duration is preferably 1200 G·min or more and 25000 G·min or less. When this product is within this range, sodium in the sample precipitates and sodium redispersion is easy. With each centrifugation operation, the proportion of hexane in the dispersion solvent increases, the viscosity of the dispersion solvent decreases, and particles tend to settle. Therefore, the preferred product value for the second or subsequent centrifugation operation becomes smaller than that for the first centrifugation operation. It is more preferable that this product be 7000 G·min or more. When determining a combination of centrifugal acceleration and duration that satisfies the above range, a duration of 10 minutes or less is economically advantageous because the time required for centrifugation is relatively short. Furthermore, a centrifugal acceleration of 5400 G or less is easily achieved using commonly available centrifuges.

[0048] By setting the centrifugation conditions so that the product of the centrifugal acceleration and the duration falls within the range specified above in each of the first and second and subsequent centrifugation operations, it becomes possible to easily separate the sodium particles from the dispersion solvent while preventing aggregation of the sodium particles and heat generation due to centrifugation.

[0049] (2) Removal operation The removal operation is an operation for at least partially removing the upper layer from the sample after centrifugation. As described above, the upper layer of the sample after centrifugation is a liquid phase mainly consisting of the dispersion solvent, and therefore, the upper layer can be selectively removed by, for example, suction or decantation. However, if an attempt is made to remove the upper layer near the interface between the upper and lower layers, there is a risk that part of the lower layer will be removed along with the upper layer, which is undesirable because it will result in a loss of sodium. Therefore, it is preferable to terminate the removal operation to the extent that only the upper layer can be removed without the lower layer. At this time, it is acceptable for part of the upper layer to remain.

[0050] (3) Addition operation The adding operation is an operation of adding a dispersion solvent to the sample after the removing operation. The dispersion solvent added here is not limited as long as it is a non-polar solvent with a boiling point of 97°C or less. In particular, since the method according to this embodiment does not include a step of heating the sample, even a non-polar solvent with a boiling point of 97°C or less (i.e., a solvent with a boiling point lower than the melting point of sodium) can be used as the dispersion solvent to be subjected to the adding operation.

[0051] Here, the non-polar solvent is the dispersion term (δ d )(J 1 / 2 / cm 3 / 2 ), polarity term (δ p )(J 1 / 2 / cm 3 / 2 ) and hydrogen bond term (δ h )(J 1 / 2 / cm 3 / 2 ) calculated from the Hansen solubility parameter δ (=(δ d 2 +δ p 2 +δ h 2 ) 1 / 2 )(J 1 / 2 / cm 3 / 2 )) in which δ d 2 / δ 2The non-polar solvent has a boiling point of 97°C or less and does not have a functional group that reacts directly with metallic sodium. Examples of non-polar solvents with a boiling point of 97°C or less include pentane, hexane, cyclohexane, heptane, and benzene. In this embodiment, hexane is used as the dispersion solvent.

[0052] The lower limit of the boiling point of the dispersion solvent used here is not particularly limited, but is, for example, 50°C or higher. Using a solvent with a boiling point of 50°C or higher can suppress the evaporation of the solvent when the sample temperature rises during centrifugation, thereby preventing an excessive increase in the internal pressure of the container during centrifugation. The boiling point of the dispersion solvent is preferably 55°C or higher, and more preferably 60°C or higher.

[0053] The dispersion solvent used here is preferably a dehydrated solvent. More specifically, it is preferable to use a solvent with a water content of 100 ppm or less. However, this does not exclude the selection of a solvent other than a dehydrated solvent.

[0054] The amount of hexane added in the addition step is preferably approximately the same as the amount of mineral oil removed in the removal step, which makes the sodium concentration in the SD approximately the same before and after steps (1) to (3), thereby suppressing changes in the handleability of the SD before and after the steps.

[0055] Furthermore, after adding hexane to the sample, the entire sample is stirred. This results in a SD in which sodium is uniformly dispersed again. The SD obtained at this time contains the mineral oil that was not removed in the removal operation and the hexane that was added in the addition operation as the dispersion solvent. In other words, an SD in which sodium is dispersed in a mixed solvent of mineral oil and hexane is formed.

[0056] (4) Repeating and terminating unit operations Each time the above steps (1) to (3) are repeated, the concentration of mineral oil in the sample decreases and the concentration of hexane increases. The repetition of the steps is terminated after an arbitrary number of cycles, and the resulting SD is designated the second SD. Note that mineral oil derived from the first SD remains in the second SD. In other words, the second SD is a dispersion in which sodium is dispersed in a dispersion solvent containing mineral oil and hexane. The remaining mineral oil in the second SD covers the sodium particles, thereby preventing aggregation of the sodium particles.

[0057] (5) Identification of the composition of the second SD The solution obtained by collecting the upper layer removed in each removal operation mainly consists of mineral oil and hexane. By removing hexane from the solution, the amount of mineral oil removed from the sample through this series of operations can be quantified. If the amount of the first SD used in the series of operations and the amount of mineral oil contained therein are known, the amount of mineral oil remaining in the second SD can be quantified. Note that hexane can be removed, for example, by evaporating the hexane using a rotary evaporator.

[0058] Alternatively, the second SD may be directly analyzed to quantify sodium, mineral oil, and hexane. Sodium can be quantified using the above-mentioned method using neutralization titration, etc. Mineral oil and hexane can be quantified using known methods such as gas chromatography and liquid chromatography. Through these quantitative procedures, the proportions (e.g., mass ratios) of sodium, mineral oil, and hexane contained in the second SD can be identified. Note that the second SD may be subjected to appropriate pretreatment depending on the quantitative procedure to be performed.

[0059] The above quantitative operation does not necessarily have to be performed every time. For example, if the relationship between the number of revolutions of the operations (1) to (3) and the proportions of sodium, mineral oil, and hexane in the SD obtained after each revolution is clarified in advance through a preliminary experiment, the number of revolutions required to obtain the desired second SD can be specified. In this case, the number of quantitative operations can be omitted in the regular production of second SD.

[0060] Additionally, if the sodium concentration of the second SD is higher than the desired concentration, hexane may be added to the second SD to prepare a third SD adjusted to the desired sodium concentration. Furthermore, if an optional solvent other than mineral oil and hexane is desired to be added, the desired amount of the solvent may be added to prepare the third SD. That is, the method according to this embodiment may include adding an optional solvent to the second dispersion to obtain a third dispersion in which sodium is dispersed in a dispersion solvent of the desired composition. For example, the amount of hexane added to the second SD may be adjusted so that the mineral oil content in the third SD is 1% by mass or more and 10% by mass or less. The third SD prepared in this manner is one embodiment of a dispersion according to the present invention.

[0061] [Composition of the Second SD] The second SD is a dispersion in which sodium is dispersed in a dispersion solvent containing mineral oil and hexane, and is one embodiment of the dispersion according to the present invention. In the second SD, the mineral oil content can be 1% by mass or more and 10% by mass or less. The mineral oil content is defined as the mass of the mineral oil contained in the dispersion divided by the total mass of the dispersion (i.e., the sum of the mass of the sodium particles, the mass of the mineral oil, and the mass of the dispersion solvent (hexane in this case)), expressed as a percentage.

[0062] Conventionally, SDs using a relatively low-viscosity solvent such as hexane as a dispersion solvent have the problem of sodium easily settling. On the other hand, in the second SD according to this embodiment, the mineral oil content is 1% by mass or more, which can suppress the settling and aggregation of sodium. The mineral oil content in the second SD is preferably 2% by mass or more, and more preferably 3% by mass or more.

[0063] Furthermore, the second SD according to this embodiment can be used to obtain a mixture of sodium and other substances by removing hexane after mixing the second SD with other substances, and the amount of mineral oil remaining in the mixture of sodium and other substances can be reduced by having a mineral oil content of 10% by mass or less. The mineral oil content in the second SD is preferably 8% by mass or less, and more preferably 5% by mass or less.

[0064] Other Embodiments Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention. [Example]

[0065] The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

[0066] [Raw material conditions] The first SD was an SD in which sodium was dispersed in mineral oil. The average particle size of the sodium in the first SD was 5 μm (5 × 10 -6 The density of the mineral oil was 850 kg / m 3 and the viscosity is 1.0×10 -2 The density of sodium is 968 kg / m 3 is.

[0067] Hexane was used as the dispersion solvent for redispersing sodium. The density of hexane is 655 kg / m 3 and the viscosity is 3.0 × 10 -4 Pa seconds.

[0068] [Equipment conditions] Centrifugation was performed using a tabletop centrifuge S300T (an example of a centrifugal separator) manufactured by Kubota Shoji Co., Ltd. The sample tube used had a body diameter of φ35 mm and a total length of 105 mm. In all examples described below, R max is 0.135m, and R min was 0.07m.

[0069] [Test 1] ( Examples 1 and 2 and Reference Examples 1 and 2 ) First, 40.0 g of SD was placed in a sample tube and centrifuged at a centrifugal acceleration of 1200 G. At this time, the angular velocity ω was 295 rad / s. The duration of the centrifugal separation was Reference example 1 So let's say it's 5 minutes. Reference example 2 So let's say it's 10 minutes. Example 1 So let's say it's 30 minutes. Example 2 The first SD contained 25% by mass of sodium, so 40.0 g of the first SD subjected to the centrifugation operation contained 10.0 g of sodium.

[0070] ( Examples 3 and 4 and Reference Examples 3 and 4 ) The centrifugal acceleration during centrifugation was changed to 1400G. Examples 1 and 2 and Reference Examples 1 and 2 The test was carried out in the same manner as above. At this time, the angular velocity ω was 319 rad / s. The duration of the centrifugation operation was Reference example 3 So let's say it's 5 minutes. Reference example 4 So let's say it's 10 minutes. Example 3 So let's say it's 30 minutes. Example 4 So we decided on 60 minutes.

[0071] ( Examples 5 and 6 and Reference Examples 5 and 6 ) The centrifugal acceleration during centrifugation was changed to 2500G. Examples 1 and 2 and Reference Examples 1 and 2 The test was carried out in the same manner as above. At this time, the angular velocity ω was 426 rad / s. The duration of the centrifugation operation was Reference example 5 So let's say it's 5 minutes. Example 5 So let's say it's 10 minutes. Example 6 So let's say it's 30 minutes. Reference example 6 So we decided on 60 minutes.

[0072] ( Examples and Reference Examples (rating) Examples 1 to 6 and Reference Examples 1 to 6 For each of the above, the sample after centrifugation was visually observed and the thickness of the cake formed at the bottom of the sample tube was measured.

[0073] The supernatant was then collected using a dropper, and 16.6 g of hexane was added to the cake after removing the supernatant, and the redispersion of sodium was examined by manual shaking. Regarding redispersibility, if a uniform dispersion was obtained, it was rated "A," if a dispersion was obtained after redispersion but visible aggregates were observed, it was rated "B," and if redispersion was not possible, it was rated "C." The weight of the collected supernatant was also measured, and the mineral oil in the supernatant was quantified.

[0074] (result) Examples 1 to 6 and Reference Examples 1 to 6 Table 1 shows the evaluation results of cake thickness and redispersibility for the above samples. When the product of centrifugal acceleration and duration was 25,000 G·min or higher, the cake thickness exceeded 3 mm, and it is believed that the sodium particles had sufficiently settled. Furthermore, since almost all (97-100%) of the supernatant liquid in this range was mineral oil, it was found that the sodium particles had sufficiently settled and only the mineral oil could be removed. Furthermore, when the product of centrifugal acceleration and duration was 84,000 G or lower, sodium redispersibility was possible. It was found that mineral oil separation could be more effectively achieved within the range where these conditions were met.

[0075] Table 1: Results of Study 1 [Table 1]

[0076] [Test 2] (Sample preparation) Example 1Centrifugation was carried out under the same conditions as in the previous test, and the supernatant was collected. After removing the supernatant, 16.6 g of hexane was added to the cake, and the sodium was re-dispersed by manual shaking to obtain a dispersion to be used for centrifugation in Test 2. Since 12 tests were to be conducted in Test 2, 12 samples were prepared using the above procedure.

[0077] Example 1 When centrifugal separation was performed under the same conditions, 21.6 g of the 40.0 g sample was collected as the supernatant. The amount of sodium contained in the supernatant was below the detection limit. Example 1 In this case, it can be said that substantially all (10.0 g) of the sodium was contained in the cake. Since substantially all (10.0 g) of the sodium was contained in the cake and the weight of the cake was 18.4 g (= 40.0 - 21.6), the weight of the mineral oil contained in the cake was 8.4 g (= 18.4 - 10.0). In other words, the dispersion solvent of the dispersion in Test 2 can be said to be a mixed solution of 8.4 g of mineral oil and 16.6 g of hexane. Calculating from this weight ratio and the above-mentioned densities and viscosities of the mineral oil and hexane, the density of the mixed solution was 721 kg / m 3 and the viscosity is 3.57 × 10 -3 Pa seconds.

[0078] (Examples 13 to 16) The redispersed samples were centrifuged at a centrifugal acceleration of 1200 G, with an angular velocity ω of 295 rad / sec. The duration of the centrifugation was 1 minute in Example 13, 3 minutes in Example 14, 5 minutes in Example 15, and 10 minutes in Example 16.

[0079] (Examples 17 to 20) The redispersed samples were centrifuged at a centrifugal acceleration of 1400 G, with an angular velocity ω of 319 rad / sec. The duration of the centrifugation was 1 minute in Example 17, 3 minutes in Example 18, 5 minutes in Example 19, and 10 minutes in Example 20.

[0080] (Examples 21 to 24) The redispersed samples were centrifuged at a centrifugal acceleration of 2500 G, with an angular velocity ω of 426 rad / sec. The duration of the centrifugation was 1 minute in Example 21, 3 minutes in Example 22, 5 minutes in Example 23, and 10 minutes in Example 24.

[0081] (Evaluation of each example) For each example, the supernatant after centrifugation was visually observed. If the supernatant was transparent, it was rated as "A," and if the supernatant was turbid, it was rated as "B."

[0082] In addition, for some Examples, the supernatant was collected, its weight was measured, and the mineral oil in the supernatant was quantified. The sum of the weight of the mineral oil quantified here and the weight of the mineral oil removed as the supernatant in Test 1 (21.6 g) was defined as the total weight of mineral oil removed in the two centrifugation operations, and the ratio of this total weight to the mineral oil contained in the first SD (30.0 g) was calculated as a percentage as the total mineral oil removal rate. Furthermore, the difference between the mineral oil contained in the first SD and this total weight was determined as the weight of mineral oil remaining in the cake after the second centrifugation operation.

[0083] (result) Table 2 shows the results of observing the supernatant for Examples 13 to 24. In all Examples, centrifugal separation results were obtained at a level that was acceptable for practical use. However, when the product of centrifugal acceleration and duration was in the range of 7000 G·min or more, a clear supernatant was stably obtained. Therefore, it can be said that it is more preferable to set the product of centrifugal acceleration and duration to 7000 G·min or more. When redispersibility was evaluated using the same method as in Test 1, uniform dispersions were obtained in all Examples 13 to 24.

[0084] Furthermore, in each case where the mineral oil contained in the supernatant was quantified, it was found that more than 90% of the mineral oil was removed through two centrifugation procedures. These results demonstrate that by appropriately setting the centrifugation conditions, it is possible to selectively remove only the mineral oil from the first SD, and that by adding hexane to the cake after the mineral oil removal and redispersing it, a dispersion in which part of the dispersion solvent has been replaced with hexane can be obtained. Dispersions in which part of the dispersion solvent has been replaced in this way can be used in processes involving chemical reactions, such as organic synthesis.

[0085] Table 2: Results of Study 2 [Table 2] [Industrial Applicability]

[0086] The present invention can be utilized to obtain a dispersion in which sodium is dispersed in a dispersion solvent containing, for example, hexane.

Claims

1. A method for obtaining a second dispersion in which sodium is dispersed in a dispersion solvent containing the non-polar solvent by at least partially replacing the mineral oil in a first dispersion in which sodium is dispersed in the mineral oil with a non-polar solvent having a boiling point of 97°C or less, the method comprising: The unit operations include a centrifugation operation of centrifuging a sample, a removal operation of at least partially removing an upper layer from the sample after the centrifugation operation, and an addition operation of adding a dispersion solvent to the sample after the removal operation, using the first dispersion as a starting sample, and using the non-polar solvent as a dispersion solvent in the adding operation, by performing the centrifugal separation operation, the removing operation, and the adding operation multiple times to obtain the second dispersion; A method in which the product of the centrifugal acceleration (unit: G) and the duration (unit: minute) in the first centrifugation operation is set to be 25,000 G·min or more and 84,000 G·min or less.

2. 2. The method according to claim 1, wherein the product of the centrifugal acceleration (unit: G) and the duration (unit: minutes) in the second or subsequent centrifugation operations is smaller than the product of the centrifugal acceleration (unit: G) and the duration (unit: minutes) in the first centrifugation operation.

3. 3. The method according to claim 1, wherein the product of the centrifugal acceleration (unit: G) and the duration (unit: min) of the centrifugation operation from the second centrifugation operation onward is 1200 G·min to 25000 G·min.

4. The method of any one of claims 1 to 3, further comprising specifying the proportions of sodium, the mineral oil, and the non-polar solvent contained in the second dispersion.

5. The method includes, as unit operations, a centrifugation operation of centrifuging a sample, a removal operation of at least partially removing an upper layer from the sample after the centrifugation operation, and an addition operation of adding a dispersion solvent to the sample after the removal operation, the method comprises using a first dispersion in which sodium is dispersed in a mineral oil as a starting sample, using a non-polar solvent having a boiling point of 97°C or less as a dispersion solvent in the adding step, and carrying out the centrifugal separation step, the removing step, and the adding step multiple times to obtain a dispersion in which sodium is dispersed in a dispersion solvent containing the non-polar solvent; A dispersion in which sodium is dispersed in a dispersion solvent, the dispersion being produced by a method in which the product of the centrifugal acceleration (unit: G) and the duration (unit: minute) in the first centrifugation operation is 25,000 G min or more and 84,000 G min or less, The dispersion solvent includes a mineral oil and a non-polar solvent having a boiling point of 97°C or less, The dispersion has a mineral oil content of 1% by mass or more and 10% by mass or less.

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