JP2011157540A - Base oil for cooling device, device-cooling oil containing the base oil, device to be cooled by the cooling oil, and device cooling method using the cooling oil - Google Patents

Abstract

An apparatus cooling base oil having excellent electrical insulation and thermal conductivity, an apparatus cooling oil blended with the base oil, an apparatus cooled by the cooling oil, and an apparatus cooling method using the cooling oil are provided. .
A base oil for equipment cooling contains 30% by mass or more of at least one of an aliphatic monoester and an aliphatic monoether, and the base oil in the main chain of the aliphatic monoester and the aliphatic monoether. The total number of terminal methyl groups, methylene groups and ether groups is 18 or more, the total number of methyl branches and ethyl branches in the aliphatic monoester and aliphatic monoether is 2 or less, and 40 ° C. of the base oil for equipment cooling The kinematic viscosity is 4 mm ² / s or more and 30 mm ² / s or less. The equipment cooling oil blended with the base oil is suitable for cooling motors, batteries, inverters, engines, batteries, and the like of electric cars and hybrid cars because of excellent electrical insulation and thermal conductivity.
[Selection figure] None

Description

  The present invention relates to an equipment cooling base oil, equipment cooling oil obtained by blending the base oil, equipment cooled by the cooling oil, and equipment cooling method using the cooling oil.

Due to the high performance of electric and hybrid vehicles, the output density of motors has increased and the amount of heat generated has also increased. For this reason, various designs have been made in the motor design, such as not only improving the heat resistance of coils and magnets, but also reducing the amount of heat generated by increasing the efficiency of the motor.
Motor cooling methods can be broadly divided into air cooling, water cooling and oil cooling. Among these, the air cooling method is excellent in that it is not necessary to prepare a cooling medium, but it is difficult to ensure a large cooling capacity. The water-cooling method is excellent in cooling because of the high thermal conductivity of water, but because of the conductivity, the motor coil cannot be directly cooled, and the necessity to stretch the cooling pipes arises, so the cooling device becomes large There is.
In contrast to these cooling systems, the oil cooling system has excellent cooling efficiency and low electrical conductivity, so that the motor can be directly cooled and a compact design can be achieved. Therefore, if it is necessary to lubricate the rotating member at the same time, the motor cooling oil can be used as the dual-purpose oil by forming the same package. For example, in a hybrid vehicle, a mechanism for circulating a transmission oil and simultaneously cooling a motor has been put into practical use. In addition, the wheel drive motor of an electric vehicle has been devised in a design that serves as both lubrication of a planetary gear and motor coil cooling by circulating lubricating oil.

As the dual-purpose oil that simultaneously performs lubrication of the transmission and the motor cooling as described above, for example, (A) a hydrocarbon group-containing zinc dithiophosphate, (B) a triaryl phosphate, and ( C) A lubricating oil composition comprising at least one of triarylthiophosphates has been proposed (see Patent Document 1). The heat transfer coefficient using a lubricating base oil having a urea adduct value of 4% by mass or less, a kinematic viscosity at 40 ° C. of 25 mm ² / s or less, and a viscosity index of 100 or more is 720 W / m ^2. A lubricating oil composition (see Patent Document 2) having a temperature of ℃ or higher or an ester-based synthetic oil in an amount of 10% by mass to 100% by mass based on the total amount of the base oil, a kinematic viscosity at 40 ° C of less than 15 mm ² / s, a viscosity The same applies to a lubricating oil composition (see Patent Document 3) having a heat transfer coefficient of 780 W / m ² · ° C. or higher using a lubricating base oil having an index of 120 or higher and a density of 0.85 g / cm ³ or higher at 15 ° C. It has been proposed as a combined oil. In each of the above-mentioned documents, it is described that the proposed lubricating oil composition is excellent in electric insulation, cooling and lubricity, and can be suitably used for an electric motor-equipped vehicle such as an electric vehicle or a hybrid vehicle. is there.

WO2002 / 097017 JP 2009-161604 A JP 2009-242547 A

  However, Patent Document 1 only mentions that the viscosity of the lubricating oil composition is low, and does not disclose any data regarding the cooling performance. Further, neopentyl glycol 2-ethylhexanoic acid diester and alkylbenzene described as base oils in the examples cannot be said to have low heat conductivity and good cooling properties. Patent Document 2 describes in paragraph [0020] of the specification that “as a urea adduct, a component that deteriorates thermal conductivity is collected accurately and reliably”. . That is, although the urea adduct component is mentioned as a component that deteriorates the thermal conductivity, it is the opposite from the actual thermal conductivity side, and “a component with a long paraffin main chain has poor thermal conductivity”. This view seems to be wrong. Therefore, it remains doubtful whether Patent Document 2 discloses a lubricating oil composition having excellent cooling performance. Further, ester compounds specifically disclosed in Patent Document 3 are azelaic acid di-2-ethylhexyl, neopentyl glycol 2-ethylhexanoic acid diester, and oleic acid 2-ethylhexyl, which are not preferable because of low thermal conductivity. .

  Therefore, an object of the present invention is to provide a base oil for equipment cooling excellent in electrical insulation and thermal conductivity, equipment cooling oil blended with the base oil, equipment cooled by the cooling oil, and equipment using the cooling oil It is to provide a cooling method.

There is a “heat transfer coefficient (unit area, unit temperature, amount of heat transfer per unit time)” as a scale indicating the cooling performance by the fluid, and the larger this value, the better the cooling performance. However, since the heat transfer coefficient is not a physical property value but a value that changes depending on conditions such as a flow velocity and a material, a design device has been devised to increase this value.
On the other hand, in order to increase the heat transfer coefficient with a device on the fluid side, the Nusselt number, Reynolds number, and Prandtl number are related, so the physical properties of the fluid are kinematic viscosity, thermal conductivity, specific heat, and density. Affect. Specifically, the smaller the kinematic viscosity, the greater the thermal conductivity, specific heat, and density, and the better the cooling performance as a fluid. Therefore, conventionally, it has been studied to improve the cooling performance by reducing the viscosity of the fluid (lubricating oil or the like). However, in the case of lubricating oil, the cooling performance improves when the viscosity is lowered, but a sufficient oil film thickness cannot be secured, resulting in poor lubrication. Therefore, the necessary minimum limit viscosity is determined by the condition of the lubrication part such as a transmission. Therefore, even with the same kinematic viscosity, a lubricating oil with higher thermal conductivity, specific heat, and density has better cooling performance. For example, the heat transfer coefficient due to forced convection of a plate with uniform temperature is proportional to the thermal conductivity of 2/3, specific heat of 1/3, and density of 1/3. Is the largest.

Therefore, a base oil with high thermal conductivity is desired as a cooling oil used in equipment such as motors. However, there have been no studies or knowledge on the correlation between the molecular structure of the base oil and the thermal conductivity. It was. Basic low molecular weight compounds are listed in the chemical handbook, that is, are known to have high thermal conductivity of alcohols such as glycerin, ethylene glycol, and methanol. However, polar compounds such as alcohol have a low volume resistivity (poor electrical insulation) and cannot be used as a cooling oil for directly cooling devices such as motors. Also, lubricity as a lubricating oil cannot be expected.
On the other hand, the present inventor has intensively studied from the viewpoint of molecular design, and found that a compound having a predetermined molecular structure is excellent in cooling property, electrical insulation property and lubricity.
That is, the present invention provides the following equipment cooling base oil, equipment cooling oil obtained by blending the base oil, equipment cooled by the cooling oil, and equipment cooling method using the cooling oil. .

(1) A base oil for equipment cooling containing 30% by mass or more of at least one of an aliphatic monoester and an aliphatic monoether, in the main chain of the aliphatic monoester and the aliphatic monoether. The total number of terminal methyl groups, methylene groups and ether groups is 18 or more, the total number of methyl branches and ethyl branches in the aliphatic monoester and aliphatic monoether is 2 or less, and 40 ° C. of the base oil for equipment cooling A base oil for equipment cooling having a kinematic viscosity of 4 mm ² / s or more and 30 mm ² / s or less.
(2) A base oil for equipment cooling according to the above (1), wherein at least one of an aliphatic monoester and an aliphatic monoether has a chain structure.
(3) The equipment cooling base oil according to (1) or (2), wherein the equipment has a thermal conductivity of 0.142 W / (m · K) or more at 25 ° C. oil.
(4) In the equipment cooling base oil as described in any one of (1) to (3) above, the equipment has a volume resistivity at 25 ° C. of 10 ¹⁰ Ω · cm or more. Base oil for use.
(5) An equipment cooling oil comprising the equipment cooling base oil according to any one of (1) to (4) above.
(6) A device that is cooled by the device cooling oil described in (5) above.
(7) The device described in (6) above is for an electric vehicle or a hybrid vehicle.
(8) The device according to (6) or (7) above, wherein the device is at least one of a motor, a battery, an inverter, an engine, and a battery.
(9) A device cooling method using the device cooling oil described in (5) above.

  The equipment cooling oil obtained by blending the equipment cooling base oil of the present invention is excellent in electrical insulation and thermal conductivity, so that motors, batteries, inverters, engines, batteries, etc. mounted on electric cars, hybrid cars, etc. Suitable for cooling.

The base oil for equipment cooling of the present invention (hereinafter also simply referred to as “base oil”) has at least one of an aliphatic monoester and an aliphatic monoether as a basic component. The total number of terminal methyl groups, methylene groups and ether groups in the main chain in the monoester and the monoether is 18 or more, and the total number of methyl branches and ethyl branches in the monoester molecule and the monoether molecule. Are both 2 or less. Here, the main chain refers to the longest chain structure in the molecule.
The present invention is described in detail below.

  In order to improve the thermal conductivity of liquid molecules, it is important to improve the transfer of thermal vibration energy due to collision between molecules and to design the molecule so that the vibration energy does not diffuse within the molecule. In order to increase the collision frequency between molecules, it is effective to lengthen the main chain of the molecule and widen the movable range of the molecule end by the rotational motion between carbon-carbon bonds. Specifically, short methyl branches and ethyl branches that diffuse vibrational energy are reduced so that vibrational energy is not diffused in the molecule and remains concentrated in the molecular main chain. The methyl group and ethyl group are also disadvantageous for collision (energy transfer) with adjacent molecules because of their small movable range. As a molecule having such a structure, an ester or ether having a long chain structure is advantageous.

  Therefore, in the present invention, an aliphatic monoester and an aliphatic monoether are used as main components of the base oil. Further, from the viewpoint of improving cooling performance, the total number of terminal methyl groups, methylene groups and ether groups in the main chain in the above-mentioned ester or ether is 18 or more. Furthermore, the total number of methyl branches and ethyl branches in the above-described ester or ether molecules is 2 or less from the viewpoint of improving the cooling performance. Further, from the viewpoint of improving cooling performance, the number of methylene groups in the above-mentioned ester or ether is preferably 17 or more. From the viewpoint of cooling properties, the above-described ester or ether is preferably a chain structure, and more preferably a linear structure that does not include a branch.

  Such an ester can be obtained by a generally known ester production method, and is not particularly limited. Examples thereof include a dehydration condensation reaction between a carboxylic acid and an alcohol, a condensation reaction between a carboxylic acid halide and an alcohol, or a transesterification reaction. For example, using a raw material with a long linear alkyl chain, the total number of terminal methyl groups, methylene groups, and ether groups in the main chain, which is the longest chain part of the molecule, is 18 or more, and short alkyl side chains (methyl) It is preferable to synthesize by reacting so that the total number of branches and ethyl branches is 2 or less.

  Examples of the raw material carboxylic acid include n-hexanoic acid, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, n-dodecanoic acid, n-tridecanoic acid, n-tetradecanoic acid, oleic acid, and ethylhexane. Examples thereof include monocarboxylic acids such as acid, butyloctanoic acid, pentylnonanoic acid, hexyldecanoic acid, heptylundecanoic acid, octyldodecanoic acid, methylheptadecanoic acid, and benzoic acid. Moreover, as raw materials for ester production, carboxylic acid esters and carboxylic acid chlorides which are derivatives of these carboxylic acids can also be used.

Examples of the starting alcohol include n hexanol, n heptanol, n octanol, n nonanol, n decanol, n undecanol, n dodecanol, n tridecanol, n tetradecanol, oleyl alcohol, ethyl hexanol, butyl octanol, pentyl nonanol, Hexyl decanol, heptyl undecanol, octyl dodecanol, methyl heptadecanol, benzyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, Diethylene glycol monopropyl ether, diethylene glycol Monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, and include monools such as triethylene glycol monobutyl ether.
As the esterification catalyst, a catalyst such as titanium tetraisopropoxide may be used, or no catalyst may be used.
The ether described above may be produced by a general ether production method such as a usual Williamson ether synthesis method, and is not particularly limited.

  The base oil of the present invention contains 30% by mass or more of the above ester or ether, but the content as the base oil is preferably 50% or more, more preferably 60% by mass or more, and 70% by mass. More preferably, it is more preferably 80% by mass or more. If a base oil having an ester or ether content of less than 30% by mass is used, the cooling performance may not be sufficiently exhibited. Of course, you may use the base oil of this invention independently (100 mass%) as a base oil for apparatus cooling.

The base oil of the present invention has a kinematic viscosity at 40 ° C. of 4 mm ² / s or more and 30 mm ² / s or less, preferably 4 mm ² / s or more and 20 mm ² / s or less. When the 40 ° C. kinematic viscosity is less than 4 mm ² / s, for example, when used as a combined oil for a motor and a transmission, the lubricity may be insufficient. On the other hand, if the 40 ° C. kinematic viscosity exceeds 30 mm ² / s, the cooling performance may be insufficient, and there may be a problem in the system circulation as cooling oil for motors and the like.

The base oil of the present invention preferably has a thermal conductivity at 25 ° C. of 0.142 W / (m · K) or more from the viewpoint of cooling properties, and more preferably 0.144 W / (m · K) or more. is there.
The base oil of the present invention preferably has a volume resistivity at 25 ° C. of 10 ¹⁰ Ω · cm or more, more preferably 10 ¹¹ Ω · cm or more, more preferably 10 ¹² Ω from the viewpoint of electrical insulation. More preferably, it is cm or more, and particularly preferably 10 ¹³ Ω · cm or more.

As a base oil of this invention, another component (base oil) can also be mixed and used for the above-mentioned compound. In that case, there are no particular limitations on the types of other components, but components that do not impair the above-described viscosity range and that do not impair the cooling performance, insulating properties, and lubricity are mixed to such an extent that the effects of the present invention are not impaired. There is a need.
Preferred examples of such other components include mineral oil and synthetic oil. Examples of the mineral oil include naphthenic mineral oil, paraffinic mineral oil, GTL mineral oil, WAX isomerized mineral oil, and the like. Specific examples include light neutral oil, medium neutral oil, heavy neutral oil, bright stock and the like by solvent refining or hydrogenation refining.
On the other hand, synthetic oils include polybutene or its hydride, poly α-olefin (1-octene oligomer, 1-decene oligomer, etc.) or its hydride, α-olefin copolymer, alkylbenzene, polyol ester, dibasic acid ester, poly Examples thereof include oxyalkylene glycol, polyoxyalkylene glycol ester, polyoxyalkylene glycol ether, hindered ester, and silicone oil.

The above-described equipment cooling oil comprising the base oil of the present invention can be suitably used for cooling motors, batteries, inverters, engines, batteries, and the like of electric vehicles and hybrid vehicles. Further, since the 40 ° C. viscosity of the base oil is also in a predetermined range, it is excellent in lubricity and is preferable as a dual-purpose oil that also lubricates planetary gears, transmissions, and the like.
In addition, various additives can be mix | blended with the apparatus cooling oil of this invention in the range which does not inhibit the objective of this invention. For example, viscosity index improvers, antioxidants, detergent dispersants, friction modifiers (oiliness agents, extreme pressure agents), antiwear agents, metal deactivators, pour point depressants, and antifoaming agents are required It can be blended accordingly. However, when equipment cooling oil is used as a dual-purpose oil, care should be taken so as to have a blended formulation that exhibits lubricating performance without impairing electrical insulation. Therefore, as equipment cooling oil, the thermal conductivity at 25 ° C. is 0.142 W / (m · K) or more, the volume resistivity at 25 ° C. is 10 ¹⁰ Ω · cm or more, and the kinematic viscosity at 40 ° C. It is desirable that the formulation is determined so that it is 4 mm ² / s or more and 30 mm ² / s or less.

  Examples of the viscosity index improver include non-dispersed polymethacrylates, dispersed polymethacrylates, olefin copolymers (for example, ethylene-propylene copolymers), dispersed olefin copolymers, styrene copolymers. (For example, styrene-diene hydrogenated copolymer). The mass average molecular weight of these viscosity index improvers is preferably 5,000 or more and 300,000 or less for, for example, dispersed and non-dispersed polymethacrylates. In the case of an olefin copolymer, about 800 or more and 100,000 or less are preferable. These viscosity index improvers can be blended singly or in any combination, but the blending amount is preferably in the range of 0.1% by mass or more and 20% by mass or less based on the total amount of cooling oil. .

  Antioxidants include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, 2,6-di-t-butylphenol, 4,4′-methylenebis (2, 6-di-t-butylphenol), isooctyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, n-octadecyl-3- (3,5-di-t-butyl-4- Phenol-based antioxidants such as hydroxyphenyl) propionate, sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate, phosphorus-based antioxidants such as phosphite, and molybdenum-based antioxidants. . These antioxidants can be contained alone or in any combination of two or more, but usually two or more combinations are preferable, and the blending amount is 0.01% by mass or more based on the total amount of the cooling oil. The mass% or less is preferable.

  Examples of cleaning dispersants include metal detergents such as alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates, alkaline earth metal phosphonates, alkenyl succinimides, benzyl amines, alkyl polyamines, alkenyl succinates. Examples include ashless dispersants such as acid esters. These detergent dispersants may be used alone or in combination of two or more. The blending amount is preferably 0.1% by mass or more and 30% by mass or less based on the total amount of cooling oil.

  Examples of friction modifiers and antiwear agents include sulfur compounds such as sulfurized olefins, dialkyl polysulfides, diarylalkyl polysulfides, diaryl polysulfides, phosphate esters, thiophosphate esters, phosphite esters, alkyl hydrogen phosphites, phosphate esters. Phosphorus compounds such as amine salts and phosphite amine salts, chlorinated oils and fats, chlorinated paraffins, chlorinated fatty acid esters, chlorinated fatty acid and other chlorinated compounds, alkyl or alkenyl maleic acid esters, alkyl or alkenyl succinic acid esters Ester compounds such as alkyl or alkenyl maleic acid, organic acid compounds such as alkyl or alkenyl succinic acid, naphthenate, zinc dithiophosphate (ZnDTP), dithiocarbamic acid Lead (ZnDTC), sulfurized oxymolybdenum organo phosphorodithioate (MoDTP), and an organic metal-based compounds such as sulfurized oxymolybdenum dithiocarbamate (MoDTC). The blending amount is preferably 0.1% by mass or more and 5% by mass or less based on the total amount of cooling oil.

Examples of the metal deactivator include benzotriazole, triazole derivatives, benzotriazole derivatives, thiadiazole derivatives, and the like, and the blending amount is preferably 0.01% by mass or less and 3% by mass or less based on the total amount of the cooling oil.
Examples of the pour point depressant include ethylene-vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene, etc. Methacrylate is preferably used. These blending amounts are preferably 0.01% by mass or more and 5% by mass or less based on the total amount of the cooling oil.
As the antifoaming agent, liquid silicone is suitable, for example, methyl silicone, fluorosilicone, polyacrylate and the like are suitable. A preferable blending amount of these antifoaming agents is 0.0005% by mass or more and 0.01% by mass or less based on the total amount of cooling oil.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Specifically, various base oils as shown in Table 1 were prepared and subjected to various evaluations. The base oil preparation method and evaluation method (physical property measurement method) are as follows.

[Example 1]
In a 500 mL four-necked flask with a Dean-Stark apparatus, 128 g of 16-methylheptadecanoic acid (trade name: isostearic acid EX manufactured by Higher Alcohol Industry Co., Ltd.) and 101 g of 1-dodecyl alcohol (reagent manufactured by Tokyo Chemical Industry Co., Ltd.), 100 ml of mixed xylene (reagent manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.1 g of titanium tetraisopropoxide (reagent manufactured by Tokyo Chemical Industry Co., Ltd.) are added, and the reaction is carried out at 140 ° C. for 2 hours while distilling off water while stirring with a nitrogen stream I let you. Thereafter, washing with a saturated saline solution and washing with a 0.1 N aqueous sodium hydroxide solution were performed three times each, followed by drying over anhydrous magnesium sulfate (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.). After filtering the magnesium sulfate, excess raw material alcohol was distilled off to obtain 182 g of n-dodecyl 16-methylheptadecanoate. Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured. The results are shown in Table 1. The results are also shown in Table 1 for the following examples and comparative examples.

[Example 2]
The same procedure as in Example 1 was carried out except that 128 g of 2-heptylundecanoic acid (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 128 g of 16-methylheptadecanoic acid, to obtain 180 g of n-dodecyl 2-heptylundecanoate. . Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured.

Example 3
16-methylheptadecanoic acid was carried out in the same manner as in Example 1 except that 134 g of 16-methylheptadecyl alcohol (trade name: Isostearyl Alcohol EX manufactured by Higher Alcohol Industry Co., Ltd.) was used instead of 101 g of 1-dodecyl alcohol. 206 g of 16-methylheptadecyl was obtained. Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured.

Example 4
Other than using 128 g of 16-methylheptadecanoic acid and 78 g of n-decanoic acid (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) and 86 g of 1-decyl alcohol (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) instead of 101 g of 1-dodecyl alcohol Was carried out in the same manner as in Example 1 to obtain 132 g of n-decyl n-decanoate. Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured.

Example 5
128 g of 16-methylheptadecanoic acid, 72 g of n-octanoic acid (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) instead of 101 g of 1-dodecyl alcohol, and 119 g of 2-octyldodecanol (Nippon Nippon Chemical Co., Ltd., trade name: NJECOAL 200A) Except that was used, the same procedure as in Example 1 was performed to obtain 132 g of 2-octyldodecyl n-octanoate. Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured.

Example 6
In a 2 L glass flask, 300 g of 2-octyldodecanol (Shin Nippon Rika Co., Ltd., trade name: NJECOAL 200A), 300 g of 1-bromooctane (reagent manufactured by Tokyo Chemical Industry Co., Ltd.), tetrabutylammonium bromide (Tokyo Chemical Industry Co., Ltd.) (Reagent) 30 g and sodium hydroxide aqueous solution 500 g (150 g of sodium hydroxide dissolved in 350 g of water) were added and stirred at 50 ° C. for 20 hours for reaction. After completion of the reaction, the reaction mixture was transferred to a separatory funnel, and the organic phase was washed 5 times with 500 mL of water, and then the organic phase was distilled to obtain 266 g of 2-octyldodecyl n octyl ether. Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured.

Example 7
In place of 128 g of 16-methylheptadecanoic acid and 101 g of 1-dodecyl alcohol, 144 g of n-octanoic acid (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) and 165 g of triethylene glycol monobutyl ether (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) were used. Was performed in the same manner as in Example 1 to obtain 188 g of n-octanoic acid ester of triethylene glycol monobutyl ether. Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured.

[Comparative Example 1]
128 g of 16-methylheptadecanoic acid, 79 g of 3,5,5-trimethylhexanoic acid (reagent manufactured by Tokyo Chemical Industry Co., Ltd.) instead of 101 g of 1-dodecyl alcohol, and 2-octyldodecanol (Shin Nippon Rika Co., Ltd.) Name: NGJEOL 200A) Except for using 119 g, the same procedure as in Example 1 was carried out to obtain 139 g of 2,5,3-trimethylhexanoic acid 2-octyldodecyl. Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured.

[Comparative Example 2]
128 g of 16-methylheptadecanoic acid, 114 g of 2,2,4,8,10,10-hexamethyl-5-undecanoic acid (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) instead of 101 g of 1-dodecyl alcohol, and 3,5 2,2,4,8,10,10-hexamethyl-5-undecanoic acid 3,5, except that 72 g of 5,5-trimethylhexanol (reagent manufactured by Tokyo Chemical Industry Co., Ltd.) was used. , 5-trimethylhexyl 148g was obtained. Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of this compound were measured.

[Comparative Example 3]
Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of 1-decanol (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) were measured.

[Comparative Example 4]
Various physical properties (thermal conductivity, volume resistivity, kinematic viscosity, viscosity index, density) of Group II refined mineral oil (Idemitsu Kosan Co., Ltd.) were measured.

[Method of measuring physical properties]
(1) Thermal conductivity Using a thermal characteristic meter KD2pro manufactured by Decagon Co., Ltd., it was measured at room temperature of 25 ° C. with a single needle sensor.

(2) Volume resistivity Measured at room temperature of 25 ° C. in accordance with JIS C 2101 No. 24 (volume resistivity test).
(3) Kinematic viscosity It measured based on the "petroleum product kinematic viscosity test method" prescribed | regulated to JISK2283.
(4) Viscosity index It measured based on the "petroleum product kinematic viscosity test method" prescribed | regulated to JISK2283.
(5) Density Density was measured according to JIS K2249 “Crude oil and petroleum products—Density test method”.
(6) The total number of terminal methyl groups, methylene groups, and ether groups in the main chain, and the total number of methyl branches and ethyl branches in the molecule 6850 type gas chromatograph manufactured by Agilent Technologies and AL-400 type NMR manufactured by JEOL After confirming the formation of, it was obtained from the structural formula.

〔Evaluation results〕
As can be seen from the results in Table 1, all of the base oils (compounds) of the present invention shown in Examples 1 to 7 have a total number of terminal methyl groups, methylene groups and ether groups in the main chain of 18 or more. Since the total number of methyl branches and ethyl branches in the molecule is 2 or less, both thermal conductivity (cooling property) and electrical insulation are excellent. Furthermore, since the kinematic viscosity is within a predetermined range, the lubricating performance is excellent. Therefore, the equipment cooling oil using the base oil of the present invention is used as cooling oil for motors, batteries, inverters, engines and batteries for electric vehicles and hybrid vehicles, and also as lubricating oil for transmissions and the like. It can be understood that is also suitable.
On the other hand, Comparative Example 1 is the same ester of 2-octyldodecanol as Example 5, but is inferior in thermal conductivity because of many methyl branches. Since the ester of Comparative Example 2 has very many methyl branches, the thermal conductivity is extremely poor. Since Comparative Example 3 is an alcohol, its thermal conductivity is good, but its electrical insulation is poor. Although the comparative example 4 is a case where refined mineral oil is used, since it is a mixture of many kinds of isomers and the above-mentioned main chain and various parameters in the molecule are not within a predetermined range, it is inferior in thermal conductivity.

Claims (9)

A base oil for equipment cooling containing 30% by mass or more of at least one of an aliphatic monoester and an aliphatic monoether,
The total number of terminal methyl groups, methylene groups and ether groups in the main chain in the aliphatic monoester and aliphatic monoether is 18 or more;
The total number of methyl and ethyl branches in the aliphatic monoester and aliphatic monoether is 2 or less;
The equipment cooling base oil has a kinematic viscosity at 40 ° C. of 4 mm ² / s or more and 30 mm ² / s or less of the equipment cooling base oil. In the base oil for equipment cooling according to claim 1,
A base oil for equipment cooling, wherein at least one of an aliphatic monoester and an aliphatic monoether has a chain structure. In the base oil for apparatus cooling of Claim 1 or Claim 2,
A base oil for equipment cooling having a thermal conductivity at 25 ° C of 0.142 W / (m · K) or more. In the base oil for apparatus cooling of any one of Claim 1- Claim 3,
The volume resistivity at 25 ° C. is 10 ¹⁰ Ω · cm or more. An equipment cooling oil comprising the equipment cooling base oil according to any one of claims 1 to 4. The equipment is cooled by the equipment cooling oil according to claim 5. The device according to claim 6 is for an electric vehicle or a hybrid vehicle. The device according to claim 6 or 7, wherein the device is at least one of a motor, a battery, an inverter, an engine, and a battery. The equipment cooling oil according to claim 5 is used. The equipment cooling method characterized by things.