JP6467908B2 - Substrate for heat medium - Google Patents

Description

  The present invention relates to a heat medium substrate, and more particularly to a heat medium substrate made of a specific ionic liquid.

Conventionally, glycols such as ethylene glycol and propylene glycol have been widely used as a base material for a heat medium such as a coolant or an antifreeze for an internal combustion engine or a fuel cell.
However, since ethylene glycol and propylene glycol are suspected of being harmful, they are designated as the first type designated chemical substances in the PRTR method.

Further, water is used as a heat medium (working medium) of the heat pipe device, but usually a water-soluble polymer and glycols are added to prevent freezing.
However, in addition to the above-mentioned harmful problems, the additive itself has a vapor pressure, which may adversely affect the boiling condensation performance of the heat pipe. There is a problem that it is limited to below the temperature.

From the above points, a heat medium excellent in safety that can be substituted for them is required, and an ionic liquid has been proposed as one such heat medium.
For example, Patent Document 1 discloses a technique of using a composition containing an imidazolium-based ionic liquid such as 1-butyl-3-methylimidazolium chloride and a rust inhibitor as a coolant for an internal combustion engine, a fuel cell, or the like. Patent Document 2 discloses a technique of using an aqueous solution of an imidazolium-based ionic liquid such as 1-butyl-3-methylimidazolium tetrafluoroborate as a working medium of a heat pipe. However, these ionic liquids have a melting point There is room for improvement in terms of fluidity and moisture content.

JP 2010-235889 A JP 2009-145038 A

  This invention is made | formed in view of such a situation, and it aims at providing the novel and useful base material for thermal media which consists of an ionic liquid.

  As a result of intensive studies in order to achieve the above object, the present inventors have obtained an ionic liquid having a predetermined pyrrolidinium cation having a low viscosity and a low melting point and good thermal stability. The present invention was completed by finding it suitable as a base material for a heat medium.

（式中、Ｒ¹は、炭素数１〜３のアルキル基を表し、Ｒ²は、メチル基またはエチル基を表し、ｎは、１または２を表し、Ｘ^-は、１価のアニオンを表す。）
２． 前記Ｘ^-が、ＢＦ₄ ^-、ＰＦ₆ ^-、ＣＦ₃ＳＯ₃ ^-、ＣＦ₃ＣＯ₂ ^-、（ＣＦ₃ＳＯ₂）₂Ｎ^-または（ＦＳＯ₂）₂Ｎ^-である１の熱媒体用基材、
３． 前記Ｘ^-が、（ＦＳＯ₂）₂Ｎ^-である２の熱媒体用基材、
４． 前記Ｒ¹が、メチル基またはエチル基を表す１〜３のいずれかの熱媒体用基材、
５． 前記Ｒ¹およびＲ²が、共にメチル基である１〜４のいずれかの熱媒体用基材、
６． 前記Ｒ¹およびＲ²が、共にメチル基であり、前記ｎが１または２である３の熱媒体用基材、
７． 前記Ｒ¹およびＲ²が、共にメチル基であり、前記ｎが１である３の熱媒体用基材、
８． １〜７のいずれかの熱媒体用基材を含む熱媒体、
９． １〜７のいずれかの熱媒体用基材のみからなる熱媒体、
１０． 前記ｎが２である６の熱媒体用基材を含むヒートパイプ装置の作動媒体、
１１． ７の熱媒体用基材を含む冷却液
を提供する。 That is, the present invention
1. A substrate for a heat medium comprising the ionic liquid represented by the formula (1),

Wherein R ¹ represents an alkyl group having 1 to 3 carbon atoms, R ² represents a methyl group or an ethyl group, n represents 1 or 2, and X ⁻ represents a monovalent anion. .)
2. 1 heat transfer group wherein X ⁻ is BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ CO ₂ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ or (FSO ₂ ) ₂ N ^−. Material,
3. 2 a substrate for a heat medium, wherein X ⁻ is (FSO ₂ ) ₂ N ⁻ ,
4). The heat medium substrate according to any one of 1 to 3, wherein R ¹ represents a methyl group or an ethyl group,
5. The heat medium substrate according to any one of 1 to 4, wherein R ¹ and R ² are both methyl groups;
6). 3 of the heat medium substrate, wherein R ¹ and R ² are both methyl groups, and n is 1 or 2,
7). 3 of the heat medium substrate, wherein R ¹ and R ² are both methyl groups and n is 1;
8). A heating medium comprising the heating medium substrate according to any one of 1 to 7,
9. A heat medium comprising only the heat medium substrate of any one of 1 to 7,
10. A working medium of a heat pipe device comprising a heat medium base material of 6 wherein n is 2;
11. A cooling liquid comprising 7 heat medium substrates is provided.

The ionic liquid used in the present invention has a relatively low melting point, a low viscosity, and excellent thermal stability.
Since the heat medium of the present invention using such an ionic liquid is not easily altered or decomposed even at a relatively high temperature, and is not easily frozen even when exposed to a temperature below freezing, it can be used in a wide temperature range from below freezing to a high temperature. .
The heat medium of the present invention is a coolant or antifreeze for devices used at high temperatures such as internal combustion engines, fuel cells, heat pipes, motors, etc .; roads, runways, glass, circulating temporary toilets, residential facilities (entrances, doors) , Toilets, drain traps, etc.) and can be suitably used as a snow melting agent.

FIG. 3 is a diagram showing a TG-DTA measurement result of MEMP • TFSA obtained in Example 1. 4 is a ¹ H-NMR spectrum diagram of MMMP · FSA obtained in Example 2. FIG. 6 is a diagram showing DSC measurement results of MMMP · FSA obtained in Example 2. FIG.

Hereinafter, the present invention will be described in more detail.
The base material for a heat medium according to the present invention is made of an ionic liquid represented by the formula (1).

R ¹ represents an alkyl group having 1 to 3 carbon atoms, and specific examples thereof may be linear, branched or cyclic, for example, methyl, ethyl, n-propyl, i-propyl, c-propyl group A linear alkyl group is preferable, and a methyl group and an ethyl group are more preferable, and a methyl group is still more preferable.
R ² represents a methyl group or an ethyl group, and is preferably a methyl group.
n represents 1 or 2.

  Among these, as the cationic structure, the following structure (A) is preferable from the viewpoint of more excellent thermal stability, and the following structure (B) is preferable from the viewpoint of lower viscosity.

X ⁻ is a monovalent anion and is not particularly limited as long as it is an anion capable of forming an ionic liquid, but in the present invention, BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ CO ₂ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ or (FSO ₂ ) ₂ N ⁻ is preferable, and BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ or (FSO _{2). 2} N ⁻ is more preferred.
In particular, (CF ₃ SO ₂ ) ₂ N ⁻ and (FSO ₂ ) ₂ N ⁻ are preferable from the viewpoint of providing an ionic liquid having a low viscosity and excellent fluidity suitable for a substrate for a heat medium. (CF ₃ SO ₂ ) ₂ N ⁻ is preferable because it gives an ionic liquid with a high decomposition point suitable as a heat medium for heat pipes used in the process, and gives an ionic liquid with a low melting point suitable as a coolant. Therefore, (FSO ₂ ) ₂ N ⁻ is more preferable.

  The ionic liquid used in the present invention can be produced by the method described in International Publication No. 2002/076924 or the specification of Chinese Patent Application No. 10147243, for example, N-alkoxyalkyl-N produced according to a conventional method. -An alkylpyrrolidinium halide (for example, chloride, bromide, etc.) and an alkali metal (for example, sodium, potassium, etc.) salt of a desired anion can be obtained by anion exchange reaction in an aqueous solvent.

  Examples of the ionic liquid that can be suitably used in the present invention include, but are not limited to, the following.

Among these, the following MEMP · TFSA, MMMP · TFSA, MEMP · FSA, and MMMP · FSA are preferable from the viewpoint of low viscosity.
In particular, as shown in the examples described later, MMMP · FSA has a very low melting point of −33 ° C. and does not freeze even below freezing, so it is suitable as a coolant, and MEMP · TFSA has a high decomposition point, so Suitable for medium.

The heat medium of the present invention may be composed only of the heat medium substrate made of the ionic liquid, or may include the heat medium substrate and another solvent.
The other solvent is appropriately selected depending on the application location and use conditions of the heat medium. For example, water; alcohol solvents such as methanol and isopropanol; ketone solvents such as acetone and methyl ethyl ketone; esters such as ethyl acetate Solvents; ether solvents such as tetrahydrofuran and diisopropyl ether; amide solvents such as N, N-dimethylformamide; aromatic solvents such as toluene; ethylene glycol, polyethylene glycol, vegetable oils, animal oils, mineral oils And synthetic oils.

  In addition, since the said ionic liquid used by this invention has comparatively low viscosity itself, when using another solvent, the usage-amount is preferably 50 mass% or less in the liquid component which comprises a heat medium, and 25 mass%. The following is more preferable, and 10% by mass or less is even more preferable, and it is optimal not to use at all (the liquid component is only an ionic liquid).

Moreover, you may add a rust preventive agent to the heat medium of this invention. The addition amount is not particularly limited, but is about 0.1 to 10% by mass in the heat medium.
Examples of the rust preventive include borate, silicate, phosphate, nitrite, nitrate, molybdate, aliphatic monobasic acid and salt thereof, aliphatic dibasic acid and salt thereof, and aromatic one. Examples include basic acids and salts thereof, aromatic dibasic acids and salts thereof, triazoles and salts thereof, thiazoles and salts thereof, and the like.

Specific examples of borates include alkali metal borates such as sodium borate.
Specific examples of the silicate include alkali metal silicates such as sodium silicate.
Specific examples of the phosphate include alkali metal phosphates such as sodium phosphate, sodium pyrophosphate, and sodium polyphosphate.
Specific examples of nitrites include alkali metal nitrites such as sodium nitrite.
Specific examples of the nitrate include alkali metal salts such as sodium nitrate.
Specific examples of molybdate include alkali metal molybdate such as sodium molybdate.

Specific examples of aliphatic monobasic acids and salts thereof include pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, oleic acid, linoleic acid, Examples include linolenic acid, ricinoleic acid, stearic acid, and alkali metal salts such as sodium salt and potassium salt of these acids.
Specific examples of the aliphatic dibasic acid and salts thereof include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, piperic acid, suberic acid, azelaic acid, sebacic acid, undecane diacid, dodecane diacid, and brassle Examples include acids, taptic acids, and alkali metal salts such as sodium salts and potassium salts of these acids.

Specific examples of aromatic monobasic acids and salts thereof include benzoic acid, nitrobenzoic acid, hydroxybenzoic acid, p-toluic acid, p-ethylbenzoic acid, p-propylbenzoic acid, p-isopropylbenzoic acid, p- Benzoic acids such as tert-butylbenzoic acid, alkoxybenzoic acids such as methoxybenzoic acid, cinnamic acid, alkyl cinnamic acid, cinnamic acids such as alkoxycinnamic acid, and sodium, potassium and lithium salts of these acids And alkali metal salts.
Specific examples of the aromatic dibasic acid and salts thereof include phthalic acid, isophthalic acid, terephthalic acid, and alkali metal salts such as sodium salt, potassium salt and lithium salt of these acids.

Specific examples of triazole and salts thereof include benzotriazole, tolyltriazole, 4-phenyl-1,2,3-triazole, 2-naphthotriazole, 4-nitrobenzotriazole, and sodium, potassium and lithium salts thereof. And alkali metal salts.
Specific examples of thiazole and salts thereof include benzothiazole, mercaptobenzothiazole, and alkali metal salts such as sodium salt, potassium salt and lithium salt thereof.

EXAMPLES Hereinafter, although a synthesis example and an Example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example.
The analyzers used in the examples are as follows.
[1] ¹ H-NMR spectrum apparatus: AL-400 manufactured by JEOL Ltd.
Solvent: Heavy dimethyl sulfoxide [2] Viscometer device: Programmable rheometer [3] DSC manufactured by BROOK FIELD
Device: DSC6200 manufactured by SII
[4] TG-DTA
Device: TG / DTA6200 made by SII

[Example 1] Synthesis of MEMP • TFSA

Pyrrolidine (manufactured by Wako Pure Chemical Industries, Ltd.) 1.51 parts by mass and 2-methoxyethyl chloride (manufactured by Kanto Chemical Co., Ltd.) 1.00 parts by mass were mixed and reacted for 1 hour while refluxing. After the reaction, the reaction solution was separated into two layers, but the lower layer solidified when allowed to cool for a while. Only the upper layer was recovered by decantation, and purified by distillation under reduced pressure to obtain 0.96 parts by mass of the target product, N-2-methoxyethylpyrrolidine (boiling point 76 ° C./vapor pressure 45 mmHg) (yield 70%).
1.00 parts by mass of the obtained N-2-methoxyethylpyrrolidine and 2 times volume of toluene (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed and placed in an autoclave, and the system is purged with nitrogen did. After making it a closed system, about 1.00 parts by mass of methyl chloride gas (manufactured by Nippon Specialty Chemicals Co., Ltd.) was added with stirring at room temperature. When methyl chloride gas was introduced, the temperature and internal pressure increased. At the maximum, the temperature increased to about 53 ° C., and the internal pressure increased to 5.5 kgf / cm ² (about 5.4 × 10 ⁵ Pa). The reaction was continued without heating, and about 0.75 parts by mass of methyl chloride gas was added after 2 days. After further reaction for 1 day, the pressure was released, and the crystals formed in the system were filtered off under reduced pressure, dried using a vacuum pump, and N-2-methoxyethyl-N-methylpyrrolidinium chloride. 1.29 parts by mass were obtained (yield 92%).
To 1.00 parts by mass of the obtained N-2-methoxyethyl-N-methylpyrrolidinium chloride, an equivalent volume of ion-exchanged water was added and stirred to dissolve. This solution was added with stirring to a solution obtained by dissolving 1.68 parts by mass of lithium bis (trifluoromethanesulfonyl) amide (manufactured by Kanto Chemical Co., Inc.) in an equivalent volume of ion-exchanged water. After reacting at room temperature for 3 hours or more, the reaction solution separated into two layers is separated, and the lower organic layer is washed twice with ion-exchanged water and then dried using a vacuum pump. 1.50 parts by mass of N-2-methoxyethyl-N-methylpyrrolidinium bis (trifluoromethanesulfonyl) amide (MEMMP · TFSA) was obtained (yield 83%).

The TG-DTA of MEMP • TFSA obtained above was measured. The result is shown in FIG.
As shown in FIG. 1, the 10% decomposition point is 399.7 ° C., and it can be seen that the heat medium substrate can be used even at a high temperature around 350 ° C.
Further, when the viscosity of MEMP · TFSA at 25 ° C. was measured, it was found to be as low as 50 cP and to have fluidity necessary as a base material for a heat medium.

[Example 2] Synthesis of MMMP FSA

A solution prepared by dissolving 14.4 parts by mass of N-methylpyrrolidine (manufactured by Wako Pure Chemical Industries, Ltd.) in 200 parts by mass of tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) was ice-cooled, and chloromethyl methyl ether was stirred. 17.1 parts by mass (manufactured by Tokyo Chemical Industry Co., Ltd.) was added. After reacting overnight, the precipitated solid was filtered under reduced pressure using a Kiriyama funnel. The obtained white solid was dried using a vacuum pump to obtain 26.7 parts by mass of an intermediate N-methoxymethyl-N-methylpyrrolidinium chloride (yield 96%).
The obtained N-methoxymethyl-N-methylpyrrolidinium chloride 8.58 parts by mass was dissolved in 10 parts by mass of ion-exchanged water. This solution was added with stirring to a solution prepared by dissolving 12.5 parts by mass of potassium bis (fluorosulfonyl) amide (manufactured by Kanto Chemical Co., Ltd.) in 5 parts by mass of ion-exchanged water. After stirring overnight at room temperature, the reaction solution separated into two layers was separated, and the lower organic layer was washed four times with ion-exchanged water and then dried using a vacuum pump. 10.2 parts by mass of -methoxymethyl-N-methylpyrrolidinium bis (fluorosulfonyl) amide (MMMP · FSA) was obtained (yield 63%). The ¹ H-NMR spectrum of MMMP · FSA is shown in FIG.

The DSC of MMMP · FSA obtained above was measured. The result is shown in FIG. As shown in FIG. 3, the melting point is −33 ° C., and it can be seen that this is a base material for heat medium that can be used up to around −30 ° C.
Further, when the viscosity at 25 ° C. of MMMP · FSA was measured, it was 20 cP, and it was found that the viscosity was further low and the fluidity required for the heat medium substrate was obtained.

Claims (11)

A base material for a heat medium comprising the ionic liquid represented by the formula (1).

Wherein R ¹ represents an alkyl group having 1 to 3 carbon atoms, R ² represents a methyl group or an ethyl group, n represents 1 or 2, and X ⁻ represents a monovalent anion. .) _2. The heat according to claim 1, wherein the X ⁻ is BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ CO ₂ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ or (FSO ₂ ) ₂ N ^−. Medium substrate. The heat medium substrate according to claim ₂ , wherein the X ⁻ is (FSO ₂ ) ₂ N ⁻ . The heat medium substrate according to claim 1, wherein R ¹ represents a methyl group or an ethyl group. The heat medium substrate according to any one of claims 1 to 4, wherein both R ¹ and R ² are methyl groups. 4. The substrate for a heat medium according to claim 3, wherein R ¹ and R ² are both methyl groups, and n is 1 or 2. 5. The base material for a heat medium according to claim 3, wherein R ¹ and R ² are both methyl groups and n is 1.   A heat medium comprising the heat medium substrate according to claim 1.   The heat carrier which consists only of the base material for heat carriers of any one of Claims 1-7.   The working medium of a heat pipe device including the base material for a heat medium according to claim 6, wherein the n is 2.   A coolant comprising the heat medium substrate according to claim 7.

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