JP2008214509A - Pressure medium oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure medium oil which does not solidify under an ultra-high pressure, especially ≥2.7 GPa at room temperature, free from dissolution trouble of a conductive paste, having low pour point and highly compatible with the material of experimental specimens and an experimental apparatus. <P>SOLUTION: The pressure medium oil contains at least one kind of silicon-containing organic compound having a kinematic viscosity of 2-30 mm<SP>2</SP>/s at 40°C, a viscosity index of ≥100 and a pour point of ≤-50°C, and has a solidification pressure of ≥2.7 GPa at room temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pressure medium oil used when an ultra-high pressure is applied to a substance.

Research that applies ultra-high pressure to materials and discovers new functions of the materials is widely conducted worldwide.
For example, in the study of organic conductors, the organic superconductor (TMTSF) ₂ PF ₆ was discovered based on a study of the metal-nonmetal transition pressure dependence, and β- (BEDT-TTF) ₂ I ₃ 8K These superconductors were discovered as a result of research on the pressure dependence of the substance (for example, see Non-Patent Document 1 and Non-Patent Document 2). The new superconductivity of these materials showed superconducting properties at 1 GPa or less. However, the superconductivity of β '-(BEDT-TTF) ₂ ICl ₂ that appeared after that was discovered at a pressure an order of magnitude higher than 8 GPa. The organic conductor showed the highest transition temperature of 14K. For this reason, a pressure medium that can withstand this high pressure measurement is required (for example, see Non-Patent Document 3).
In this way, the development of new materials has been pursued by pursuing and elucidating changes in physical properties due to changes in pressure, as well as temperature (very low temperature) and magnetic fields, for solid materials such as organic superconductors and oxide conductors. Has been done.

In such a case, a pressure medium, particularly a liquid pressure medium, is usually used as means for applying an ultrahigh pressure to the substance, and the target substance is applied via this pressure medium. This is because it is necessary to apply a hydrostatic pressure, that is, a gentle and uniform pressure to the application target substance.
Therefore, the pressure medium is required to be liquid over a wide pressure range. This is because if it is solidified in an actual application state, it becomes uniaxial compression and uniform compression cannot be performed. That is, the pressure medium is first required to have a high solidification pressure at room temperature. Secondly, in the case of measuring electric conductivity under pressure, a conductive paste is often used for the electrode, and it is required that the medium does not dissolve the paste. Third, even if the pressure medium is liquid during pressurization, it solidifies when the temperature is lowered to room temperature or lower. If there is a large pressure change during this solidification, the fragile sample will be destroyed. In addition to that, it is of course necessary to be compatible with the materials used in the experiment and the materials of the experimental apparatus.

  By the way, normal pressure liquids for ultra-high pressure include conventional petroleum fractions (such as naphthenic mineral oil), hydrocarbons such as isopentane and poly-alpha olefins, a mixture of methanol and ethanol, and a mixture of water and glycerin. Alcohols such as are known. Moreover, in what is marketed as a pressure medium oil, there exists Fluorinert 70/77 (made by Sumitomo 3M).

Journal of physical letter, vol40, L-385 (1979) Journal of physical society jpn, vol54, (1985) 2084 Journal of Physical Society Japan, vol72, (2003) 468.

However, Fluorinert 70/77 (manufactured by Sumitomo 3M Co.) has a solidification pressure at room temperature as low as 1 GPa, and a solidification pressure in a mixed solution of water and glycerin is even lower. The solidification pressure of the poly α olefin is 2.2 GPa or more and less than 2.7 GPa, but a medium having a solidification pressure higher than this has been demanded.
On the other hand, with isopentane, the pressure change at the solidification temperature at the time of temperature drop was severe, and fragile samples were frequently destroyed. Moreover, although the solidification pressure of the mixed solution of methanol and ethanol is much higher as 10 GPa, there is a problem that the conductive paste of the electrode material is dissolved.
Accordingly, there has been a demand for the development of a pressure medium oil that has a high solidification pressure at room temperature and can be adapted to the materials used in the experiment and the experimental apparatus.

  It is an object of the present invention to be a sample or an experimental apparatus that does not solidify at room temperature, even under an ultrahigh pressure of 2.7 GPa or higher, does not dissolve the conductive paste, has a low pour point, and is used for experiments. It is to provide a pressure medium oil excellent in compatibility with the material.

In order to solve the above problems, the present invention provides the following pressure medium oil.
(1) A pressure medium oil comprising a silicon-containing organic compound having a kinematic viscosity at 40 ° C. of ² to 30 mm ² / s, a viscosity index of 100 or more, and a pour point of −50 ° C. or less.

（式中、Ｘはアルキル基、ｎは２〜２４の整数である。）
（３）前記オルガノポリシロキサンは、ポリジエチルシロキサン、ポリジメチルシロキサンから選ばれる少なくとも１種であることを特徴とした上記（２）に記載の圧力媒体油。
（４）前記オルガノポリシロキサンは、４０℃における動粘度が３〜１５ｍｍ^２／ｓ、かつ、粘度指数が１２０以上であることを特徴とした上記（２）または（３）に記載の圧力媒体油。 (2) The pressure medium oil according to (1), wherein the silicon-containing organic compound is an organopolysiloxane represented by the following general formula (1).

(In the formula, X is an alkyl group, and n is an integer of 2 to 24.)
(3) The pressure medium oil as described in (2) above, wherein the organopolysiloxane is at least one selected from polydiethylsiloxane and polydimethylsiloxane.
(4) The pressure medium oil according to (2) or (3) above, wherein the organopolysiloxane has a kinematic viscosity at 40 ° C. of 3 to 15 mm ² / s and a viscosity index of 120 or more. .

（式中、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４は炭素数２〜１２の直鎖アルキル基である。）
（６）前記テトラアルキルシランは、ジエチルオクチルシラン、ジエチルジヘキシルシラン、ジエチルジデシルシラン、トリエチルデシルシラントリヘキシルエチルシラン、トリヘキシルブチルシラン、テトラヘキシルシラン、トリヘキシルオクチルシランから選ばれる少なくとも１種であることを特徴とした上記（５）に記載の圧力媒体油。
（７）前記テトラアルキルシランは、４０℃における動粘度が３〜１５ｍｍ^２／ｓ、かつ、粘度指数が１００以上であることを特徴とした上記（５）または（６）に記載の圧力媒体油。 (5) The pressure medium oil according to (1), wherein the silicon-containing organic compound is a tetraalkylsilane represented by the following general formula (2).

(In the formula, R ₁ , R ₂ , R ₃ and R ₄ are linear alkyl groups having 2 to 12 carbon atoms.)
(6) The tetraalkylsilane is at least one selected from diethyloctylsilane, diethyldihexylsilane, diethyldidecylsilane, triethyldecylsilanetrihexylethylsilane, trihexylbutylsilane, tetrahexylsilane, and trihexyloctylsilane. The pressure medium oil as described in (5) above, wherein
(7) The pressure medium oil according to (5) or (6) above, wherein the tetraalkylsilane has a kinematic viscosity at 40 ° C. of 3 to 15 mm ² / s and a viscosity index of 100 or more. .

(8) The pressure medium oil according to any one of (1) to (7) above, wherein the solidification pressure at room temperature (25 ° C.) is 2.7 GPa or more.

  According to the pressure medium oil of the present invention, the solidification pressure is high and the pour point is low. Pressure can be applied. In addition, since the silicon-containing organic compound has good compatibility with the sample used in the experiment and the material of the experimental apparatus, the conventional experimental sample and the experimental apparatus can be used as they are.

The pressure medium oil of the present invention comprises at least one silicon-containing organic compound and satisfies the following conditions.
The silicon-containing organic compound has a kinematic viscosity at 40 ° C. of ² to 30 mm ² / s, more preferably 3 to 15 mm ² / s. If the kinematic viscosity at 40 ° C. is less than 2 mm ² / s, there is a risk of loss due to evaporation of the pressure medium oil or ignition, which is inappropriate, and if it exceeds 30 mm ² / s, the solidification pressure of the pressure medium oil decreases. There is.
The viscosity index of the silicon-containing organic compound is 100 or more, more preferably 110 or more. When the viscosity index is less than 100, the solidification pressure may decrease, which is not preferable.
Furthermore, the pour point of the silicon-containing organic compound needs to be −50 ° C. or lower. When the pour point exceeds −50 ° C., the solidification pressure decreases, and the experimental operation in the low temperature experiment becomes difficult.

As the silicon-containing organic compound contained in the pressure medium oil of the present invention, an organopolysiloxane represented by the following general formula (1) can be used. Organopolysiloxane further satisfies the following conditions.
The organopolysiloxane has a kinematic viscosity at 40 ° C. of 3 to 15 mm ² / s, more preferably 4 to 15 mm ² / s. If the kinematic viscosity at 40 ° C. is less than 3 mm ² / s, there is a risk of loss due to evaporation of pressure medium oil or ignition, which is inappropriate. If it exceeds 15 mm ² / s, the solidification pressure of the pressure medium oil decreases. There is.

  The viscosity index of the organopolysiloxane is 120 or more, more preferably 130 or more, and still more preferably 150 or more. If the viscosity index is less than 120, the solidification pressure may decrease, which is not preferable.

  In the formula, X is an alkyl group having 1 to 2 carbon atoms, and X may be the same or different alkyl group. N is an integer of 2 to 24, preferably 4 to 10. Typical examples of the organopolysiloxane represented by the general formula (1) include polydiethylsiloxane and polydimethylsiloxane.

Further, the silicon-containing organic compound contained in the pressure medium oil of the present invention may be a tetraalkylsilane represented by the following general formula (2), and the tetraalkylsilane further satisfies the following conditions. is there.
The tetraalkylsilane has a kinematic viscosity at 40 ° C. of 3 to 15 mm ² / s, more preferably 4 to 15 mm ² / s. If the kinematic viscosity at 40 ° C. is less than 3 mm ² / s, there is a risk of loss due to evaporation of pressure medium oil or ignition, which is inappropriate. If it exceeds 15 mm ² / s, the solidification pressure of the pressure medium oil decreases. There is.
Further, the viscosity index of tetraalkylsilane is 100 or more, more preferably 110 or more. If the viscosity index is less than 100, the solidification pressure may decrease, which is not preferable.

In the formula, the monovalent hydrocarbon group having 2 to 12 carbon atoms represented by R ₁ , R ₂ , R ₃ and R ₄ is preferably a linear alkyl group having 2 to 12 carbon atoms.

  Representative examples of the tetraalkylsilane represented by the general formula (2) include diethyldioctylsilane, diethyldihexylsilane, diethyldidecylsilane, triethyldecylsilanetrihexylethylsilane, trihexylbutylsilane, tetrahexylsilane, and trihexyl. Examples include octylsilane.

  A pressure medium oil composed of a silicon-containing organic compound having such characteristics has a solidification pressure at room temperature of 2.7 GPa or more, more preferably 3.0 GPa or more, and further preferably 3.5 GPa or more. When the solidification pressure is less than 2.7 GPa, when an ultra-high pressure of 2.7 GPa or more is applied, the pressure medium oil is solidified, and the target substance cannot be uniformly applied with pressure. Therefore, the pressure medium oil of the present invention exists as a liquid even at an ultrahigh pressure, particularly at an ultrahigh pressure of 2.7 GPa or more, and can fully exert its role as a pressure medium.

In the present invention, the aforementioned silicon-containing organic compound may be used alone or in combination of two or more. The mixing ratio when two or more kinds are mixed can be arbitrarily selected.
The pressure medium oil of the present invention can be blended with known additives within the scope of the object of the present invention.

  For example, detergent dispersants such as succinimide and boron succinimide, antioxidants such as phenols and amines, corrosion inhibitors such as benzotriazoles and thiazoles, metal sulfonates and succinates Examples include rust inhibitors, antifoaming agents such as silicon and fluorinated silicon, and viscosity index improvers such as polymethacrylates and olefin copolymers.

  Examples of amine-based antioxidants include monoalkyldiphenylamines such as monooctyldiphenylamine and monononyldiphenylamine, 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, 4,4′-dihexyldiphenylamine, 4, 4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, dialkyldiphenylamines such as 4,4'-dinonyldiphenylamine, polyalkyldiphenylamines such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine , Α-naphthylamine, phenyl-α-naphthylamine, butylphenyl-α-naphthylamine, pentylphenyl-α-naphthylamine , Hexylphenyl -α- naphthylamine, heptylphenyl -α- naphthylamine, octylphenyl -α- naphthylamine, there may be mentioned naphthylamine such as nonylphenyl -α- naphthylamine, among others those of the dialkyl diphenylamine is preferred.

Examples of the phenol-based antioxidant include monophenols such as 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butyl-4-ethylphenol, 4,4′- Examples include diphenols such as methylene bis (2,6-di-tert-butylphenol) and 2,2′-methylene bis (4-ethyl-6-tert-butylphenol).
These antioxidants may be used individually by 1 type, and may be used in combination of 2 or more type.

  Moreover, what is necessary is just to select the compounding quantity of these additives suitably according to the objective, However, It is preferable that the sum total of these additives is 10 mass% or less normally on a composition basis.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not restrict | limited at all to the content of description of these Examples.
Samples comprising the compounds listed in Examples 1 and 2 and Comparative Examples 1 and 2 were prepared, and various properties were evaluated by the methods described below. In addition, the additive etc. are not added at all to the sample.

[Kinematic viscosity]
The measurement was performed according to “JIS K 2283”.

[Viscosity index]
The measurement was performed according to “JIS K 2283”.

[density]
The measurement was performed according to “JIS K 2249”.

[Pour point]
The measurement was performed according to “JIS K 2269”.

[Solidification pressure]
A strain gauge was placed in a pressurized container formed in a cubic shape and filled with pressure medium oil. In order to apply an ultra-high pressure, pressure was applied from six directions of the pressurized container, and the resistance value of the strain gauge at this time was measured. The relationship between the pressure and the resistance value was graphed, and the point at which the curve of the resistance value against pressure was bent discontinuously was specified as the solidification pressure point.

  The strain gauge is a plate-like measuring element, and the resistance value decreases as it is compressed. When the pressure medium oil is a liquid, the entire element is compressed evenly and contracts, but when the pressure medium oil is solidified and pressurized, the compression of the pressure medium oil is also detected and the strain gauge compressibility increases. The resistance value suddenly decreases at the solidification pressure point. For this reason, the point where the curve of the resistance value with respect to the pressure bends appears on the graph.

[Dissolution of conductive paste]
The presence or absence of dissolution of the conductive paste was confirmed visually.

[Pressure change during solidification]
The pressure when the pressure medium oil solidified when the temperature was lowered to room temperature or lower was measured, and the degree of change was shown.

The compounds used in Examples 1 and 2 and Comparative Examples 1 and 2 are shown below.
[Example 1]
Diethyldioctylsilane

[Example 2]
Polydiethylsiloxane

[Comparative Example 1]
Polymethylphenylsiloxane

[Comparative Example 2]
Table 1 shows the measurement results of poly-α-olefin.

  As Table 1 shows, in Example 1 and Example 2, the result of a very high room temperature solidification point of 3.7 GPa was obtained. That is, the pressure medium oil of Example 1 and Example 2 can exist in a liquid state up to 3.7 GPa, and can be used as a pressure medium oil even under ultra high pressure. Moreover, there was no dissolution of the conductive paste, and the pressure change when solidifying when the temperature was lowered to room temperature or lower was also gradual.

  On the other hand, in Comparative Example 1, polymethylphenylsiloxane, which is a silicon-containing organic compound, is used. However, since the kinematic viscosity at 40 ° C. is off, the room temperature solidification point is low. Moreover, in the comparative example 2, since the poly alpha olefin which is not a silicon-containing organic compound is used, the room temperature solidification point is low and the objective of this invention is not achieved.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used as a pressure medium oil used in an ultrahigh pressure application system, particularly an ultrahigh pressure application system that applies an ultrahigh pressure of 2.7 GPa or more.

Claims (8)

A kinematic viscosity at 40 ° C. of ² to 30 mm ² / s, and
A viscosity index of 100 or more, and
A pressure medium oil comprising a silicon-containing organic compound having a pour point of -50 ° C or lower. The pressure medium oil according to claim 1,
The pressure medium oil, wherein the silicon-containing organic compound is an organopolysiloxane represented by the following general formula (1).

(In the formula, X is an alkyl group, and n is an integer of 2 to 24.) The pressure medium oil according to claim 2,
The pressure medium oil according to claim 1, wherein the organopolysiloxane is at least one selected from polydiethylsiloxane and polydimethylsiloxane. In the pressure medium oil according to claim 2 or 3,
The above-mentioned organopolysiloxane has a kinematic viscosity at 40 ° C. of 3 to 15 mm ² / s and a viscosity index of 120 or more. The pressure medium oil according to claim 1,
The pressure medium oil, wherein the silicon-containing organic compound is a tetraalkylsilane represented by the following general formula (2).

(In the formula, R ₁ , R ₂ , R ₃ and R ₄ are linear alkyl groups having 2 to 12 carbon atoms.) In the pressure medium oil according to claim 5,
The tetraalkylsilane is at least one selected from diethyloctylsilane, diethyldihexylsilane, diethyldidecylsilane, triethyldecylsilane, trihexylethylsilane, trihexylbutylsilane, tetrahexylsilane, and trihexyloctylsilane. Feature pressure medium oil. In the pressure medium oil according to claim 5 or 6,
The tetraalkylsilane is a pressure medium oil having a kinematic viscosity at 40 ° C. of 3 to 15 mm ² / s and a viscosity index of 100 or more. In the pressure medium oil in any one of Claims 1-7,
A pressure medium oil having a solidification pressure of 2.7 GPa or more at room temperature (25 ° C.).