Heat medium

Abstract

Provided is an incombustible heat medium having a small environmental load and high insulation properties. The heat medium according to the present invention comprises a compound (A) represented by formula (1).　(1): RA-O-R1-O-RB In formula (1), RA is a perfluoroalkenyl group having 2 to 4 carbon atoms, RB is a fluoroalkyl group having 2 to 4 carbon atoms or a fluoroalkenyl group having 2 to 4 carbon atoms, and R1 is an alkylene group having 1 to 4 carbon atoms.

Description

heat medium

[0001] The present invention relates to a heat transfer medium using a hydrofluoroether olefin (HFEO).

[0002] Heat transfer media are used in a variety of heat transfer means, such as for controlling the temperature of wafers in semiconductor manufacturing, for cooling and heating semiconductor elements and electronic components, for cooling servers, and for controlling the temperature of heat pumps, heat pipes, and thermostatic baths.

[0003] Conventionally, perfluorocarbons (PFCs) have been widely used as heat transfer media because they are non-flammable and have low ozone depletion potential (ODP), etc. However, PFCs have the problem of having a high global warming potential (GWP) and a large impact on the environment due to the greenhouse effect.

[0004] For this reason, the use of HFEs (hydrofluoroethers), which have low ODP and GWP and have a smaller impact on the environment, has been investigated as a heat transfer medium to replace PFCs (see, for example, Patent Document 1).

[0005] Special Publication No. 2007-524737

[0006] For example, in a dry etching process using plasma in semiconductor manufacturing, a heat transfer medium may be used under harsh conditions of a high electric field and a high temperature environment. For this reason, the heat transfer medium is required to have not only thermal conductivity but also excellent electrical properties such as high insulation. In addition, a heat transfer medium with a smaller environmental impact than conventional HFEs is also desired.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a non-flammable heat transfer medium that has a small environmental impact and high insulating properties.

[0008] The present invention is based on the discovery that HFEO, which has a structure in which hydrogen fluoride is desorbed from HFE, can be used as a heat transfer medium that has a small environmental impact and high insulating properties.

[0009] The present invention provides the following means: [1] A heat transfer medium containing a compound (A) represented by the following formula (1): R Ａ -O-R １ -O-R Ｂ(1) In formula (1), R Ａ is a perfluoroalkenyl group having 2 to 4 carbon atoms, and R Ｂ is a fluoroalkyl group having 2 to 4 carbon atoms or a fluoroalkenyl group having 2 to 4 carbon atoms, and R １ is an alkylene group having 1 to 4 carbon atoms. [2] R Ａ The heat medium according to [1], wherein the perfluoroalkenyl group is one of the carbon atoms constituting the carbon-carbon double bond and the adjacent oxygen atom. [3] R Ｂ The heat medium according to [1] or [2], wherein the fluoroalkenyl group is one of the carbon atoms constituting the carbon-carbon double bond and bonded to an adjacent oxygen atom. [4] R Ｂ is a fluoroalkyl group having one hydrogen atom and having 2 to 4 carbon atoms. [5] The heat medium of [1], wherein compound (A) is 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene, 1,2,3,3,3-pentafluoro-1-[3-(1,1,2,3,3,3-hexafluoropropoxy)propoxy]-1-propene, or 1,2,3,3,4,4,4-heptafluoro-1-[2-(1,1,2,3,3,4,4,4-octafluorobutoxy)ethoxy]-1-butene. [6] The heat medium of any of [1] to [5], wherein the content of compound (A) is 50 mass% or more. [7] A heat transfer medium according to any one of [1] to [6], used for cooling or heating components in semiconductor manufacturing equipment.

[0010] According to the present invention, it is possible to provide a non-flammable heat transfer medium that has a small environmental impact and high insulating properties.

[0011] The heat transfer medium according to an embodiment of the present invention (hereinafter also referred to as the present embodiment) contains a compound (A) represented by the following formula (1): Ａ -O-R １ -O-R Ｂ (1)

[0012] In formula (1), R Ａ is a perfluoroalkenyl group having 2 to 4 carbon atoms, and R Ｂis a fluoroalkyl group having 2 to 4 carbon atoms or a fluoroalkenyl group having 2 to 4 carbon atoms, and R １ is an alkylene group having 1 to 4 carbon atoms.

[0013] Compound (A) is HFEO. HFEO has a carbon-carbon double bond that is easily decomposed by active oxygen such as hydroxyl radicals in the atmosphere, and therefore has a short atmospheric lifetime, a low GWP, and a small impact on the global environment. Compound (A) is a fluorine compound, and like HFE, it has no flash point and is non-flammable. Furthermore, compound (A) has higher insulating properties than the commonly used HFE. Therefore, the heat transfer medium of this embodiment has a small environmental load, high insulating properties, and is non-flammable.

[0014] The GWP is an estimated value obtained by integrating the intensity of the greenhouse effect (radiant energy given to the Earth) per concentration when a target substance is released into the atmosphere over 100 years, with carbon dioxide as the reference value of 1. The GWP of the compound represented by formula (1) can be estimated based on the chemical structure from the GWP values ​​of known fluorine-based heat transfer media. The ODP is a numerical value that represents the relative value of the amount of destruction that a target substance will cause to the ozone layer when released into the atmosphere, with the amount of ozone destruction per kg of CFC-11 (trichlorofluoromethane) as the reference value of 1.0. HFEO does not contain any halogens other than fluorine, and therefore, like HFEs, its ODP is 0.

[0015] From the viewpoint of stable use in a high electric field environment, the heat transfer medium preferably has a breakdown voltage (when the electrode gap is 2.5 mm) of 20 kV or more, more preferably 30 kV or more, and even more preferably 40 kV or more.

[0016] From the viewpoint of efficient heat transfer, the heat medium has a heat capacity per unit volume (25°C) of preferably 1.5 kJ / (L K) or more, more preferably 1.6 kJ / (L K) or more, and even more preferably 1.7 kJ / (L K) or more. Also, from the viewpoint of efficient heat transfer, the heat medium has a thermal conductivity (25°C) of preferably 50 mW / (m K) or more, more preferably 60 mW / (m K) or more, and even more preferably 70 mW / (m K) or more.

[0017] The content of compound (A) in the heat transfer medium of this embodiment is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 95% by mass or more, and even more preferably 99% by mass or more, from the viewpoint of obtaining a stable heat transfer medium in which the properties of the compound are fully exhibited. The heat transfer medium of this embodiment may contain compound (A) and an inactive compound, for example, another compound that functions as a heat transfer medium, an additive that improves fluidity, etc., and may also contain impurities, but from the viewpoint of stable temperature control, it is particularly preferable that the content of compound (A) is 100% by mass.

[0018] R Ａ The perfluoroalkenyl group in R has 2 to 4 carbon atoms, preferably 3 or 4 carbon atoms, from the viewpoints of fluidity as a heat transfer medium and ease of production. The carbon chain of the perfluoroalkenyl group may be linear or branched, and is preferably linear. Ａ In terms of fluidity as a heat transfer medium, ease of production, and the like, it is preferable that either one of the carbon atoms constituting the carbon-carbon double bond of the perfluoroalkenyl group be bonded to the adjacent oxygen atom.

[0019] R Ｂ is a fluoroalkyl group having 2 to 4 carbon atoms or a fluoroalkenyl group having 2 to 4 carbon atoms, and is preferably a fluoroalkyl group having 2 to 4 carbon atoms and one hydrogen atom.

[0020] R Ｂ When R is a fluoroalkyl group, it has 2 to 4 carbon atoms, preferably 3 or 4 carbon atoms, from the viewpoints of fluidity as a heat transfer medium and ease of production. The carbon chain of the fluoroalkyl group may be linear or branched, and is preferably linear. Ｂ The fluoroalkyl group preferably has one hydrogen atom, and this hydrogen atom may be bonded to any carbon atom. Ｂ is preferably a hydrogen atom (β hydrogen) bonded to the second carbon atom from the oxygen atom (etheric oxygen atom) adjacent to the

[0021] R ＢWhen R is a fluoroalkenyl group, it has 2 to 4 carbon atoms, preferably 3 or 4 carbon atoms, from the viewpoints of fluidity as a heat transfer medium and ease of production. The carbon chain of the fluoroalkenyl group may be linear or branched, and is preferably linear. Ｂ In terms of fluidity as a heat transfer medium, ease of production, etc., it is preferable that one of the carbon atoms constituting the carbon-carbon double bond of the fluoroalkenyl group R be bonded to the adjacent oxygen atom. Ｂ The fluoroalkenyl group may have a hydrogen atom, but is preferably a perfluoroalkenyl group, and R Ａ A perfluoroalkenyl group identical to the above is preferred.

[0022] R １ is an alkylene group having 1 to 4 carbon atoms, preferably 2 to 4 carbon atoms, and more preferably 2 to 3 carbon atoms. The carbon chain may be linear or branched, and is preferably linear.

[0023] Specific examples of the compound represented by formula (1) include 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene (CF ３ CF = CFOCH ２ CH ２ OCF ２ CHFCF ３ ), 1,2,3,3,3-pentafluoro-1-[3-(1,1,2,3,3,3-hexafluoropropoxy)propoxy]-1-propene (CF ３ CF = CFOCH ２ CH ２ CH ２ OCF ２ CHFCF ３ ), 1,2,3,3,4,4,4-heptafluoro-1-[2-(1,1,2,3,3,4,4,4-octafluorobutoxy)ethoxy]-1-butene (CF ３ CF ２ CF = CFOCH ２ CH ２ OCF ２ CHFCF ２ CF ３Among these, 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene is preferred in view of its excellent insulating properties and ease of production.

[0024] The method for producing the compound (A) is not particularly limited, and the compound (A) can be produced by a known method. For example, the compound (A) can be produced by a known synthesis method, such as a method in which a fluoroolefin and a diol are subjected to an addition reaction in the presence of an alkali catalyst such as potassium carbonate, and then a hydrogen fluoride elimination reaction is carried out in the presence of a strong base such as an alkali metal alkoxide.

[0025] The heat transfer medium of this embodiment can be used, for example, for controlling the temperature of wafers in semiconductor manufacturing, for cooling and heating semiconductor elements and electronic components, for cooling servers, for heat pumps, heat pipes, thermostatic baths, etc. Compound (A) has good insulating properties and is therefore suitable for cooling or heating components in semiconductor manufacturing equipment, and can particularly withstand harsh conditions of high electric field and high temperature environments, such as a dry etching process using plasma in semiconductor manufacturing.

[0026] The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

[0027] The reaction products were identified by proton nuclear magnetic resonance ( １ H NMR) spectrum, fluorine-19 nuclear magnetic resonance ( １９ F NMR) spectrum and gas chromatography mass spectrometry (GC-MS (column used: "DB-1301", length 60 m, inner diameter 250 μm, thickness 1 μm; manufactured by Agilent Technologies, Inc.)).

[0028] [Example 1] Production of Compound 1 223 g of potassium carbonate (manufactured by Junsei Chemical Co., Ltd.), 200 g of ethylene glycol (manufactured by Junsei Chemical Co., Ltd.), and 400 g of anhydrous acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a stainless steel autoclave (internal volume 2.1 liters) equipped with a stirrer, and the autoclave was sealed and maintained at 20°C. The contents of the autoclave were stirred, and 966 g of hexafluoropropene (manufactured by AGC Inc.) was added in a gaseous state over 6 hours. After maintaining the mixture at 20°C for 1 hour to allow the reaction, the crude reaction liquid in the autoclave was recovered by filtration. The recovered crude reaction liquid contained 45% by mass of 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane (HFE (1a)). Next, 1000 g of the reaction crude liquid was placed in a Hastelloy (registered trademark) autoclave (internal volume: 2.1 liters), and 100 g of anhydrous hydrogen fluoride (manufactured by AGC Inc.) was added and stirred for 1 hour. The resulting reaction crude liquid was phase-separated, washed with water, dried over molecular sieve 3A (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and then purified by distillation to obtain HFE (1a).

[0029] Next, 117 g of tert-butyl alcohol (manufactured by Kanto Chemical Co., Inc.) and 75 g of HFE (1a) were placed in a glass reactor (internal volume 0.5 liters) equipped with a stirrer, heated to 40°C with stirring, and 100 g of potassium tert-butoxide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added intermittently over 5 hours. After maintaining the temperature at 40°C for 2 hours to allow the reaction, the reaction crude liquid was neutralized with hydrochloric acid at a concentration of 1 mol / L and washed with water. The organic layer was recovered and purified by distillation to obtain 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene (CF ３ CF = CFOCH ２ CH ２ OCF ２ CHFCF ３ Compound 1) was obtained.

[0030] [Example 2] Preparation of Compound 2 In Example 1, ethylene glycol, a raw material for synthesizing HFE (1a), was changed to propylene glycol, and the rest was the same as in Example 1 to prepare 1,2,3,3,3-pentafluoro-1-[3-(1,1,2,3,3,3-hexafluoropropoxy)propoxy]-1-propene (CF ３ CF = CFOCH ２ CH ２ CH ２ OCF ２ CHFCF ３ Compound 2) was prepared.

[0031] Example 3: Preparation of Compound 3 In Example 1, hexafluoropropene, a raw material for synthesizing HFE (1a), was changed to octafluorobutene, and the same procedure as in Example 1 was repeated to prepare 1,2,3,3,4,4,4-heptafluoro-1-[2-(1,1,2,3,3,4,4,4-octafluorobutoxy)ethoxy]-1-butene (CF ３ CF ２ CF = CFOCH ２ CH ２ OCF ２ CHFCF ２ CF ３ Compound 3) was prepared.

[0032] [Evaluation of Physical Properties] The GWP, ODP, flash point, and breakdown voltage of Compounds 1 to 3 are shown in Table 1. For comparison and reference, Compound 4 was prepared using a commercially available HFE, Novec-7500 ("Novec (registered trademark) 7500", manufactured by 3M Co.; 3-ethoxy-2-(trifluoromethyl)-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluorohexane (CF ３ CF ２ CF ２ CF (OCH ２ CH ３ )CF(CF ３ ) ２ The physical properties (catalog values) of the above-mentioned compound are also shown as Example 4 in Table 1.

[0033] The GWP indicates the estimated value described above. As described above, the ODP is 0 in all cases. The presence or absence of a flash point was determined by the tag sealing method (JIS K 2265-1:2007). If there is no flash point, it can be said that the material is non-flammable. The breakdown voltage was measured in accordance with JIS C 2101:2100 using a dielectric breakdown tester ("YST-243AT-B100", manufactured by Yamayo Test Instruments Co., Ltd.; electrode gap 2.5 mm).

[0034] Furthermore, the heat capacity and thermal conductivity of Compounds 1 to 4 were measured to evaluate their heat transfer performance. The results are also shown in Table 1. The heat capacity was measured at 25°C using a differential scanning calorimetry (DSC) device ("DSC 8500", manufactured by PerkinElmer). The thermal conductivity was measured at 25°C by a transient hot wire heating method using a transient hot wire measuring device with a platinum wire having a wire diameter of 10 μm and a length of 80 mm.

[0035]

[0036] As shown in Table 1, the HFEOs of compounds 1 to 3, like the HFE of compound 4, have an ODP of 0 and no flash point. Furthermore, they have a smaller GWP and a higher breakdown voltage than compound 4. From this, it can be said that compounds 1 to 3 have a small environmental impact, are non-flammable, and have better insulating properties than compound 4, a conventional heat transfer medium. Furthermore, the HFEOs of compounds 1 to 3 have a larger heat capacity and higher thermal conductivity than the HFE of compound 4, and can be said to be heat transfer mediums with excellent heat transfer performance.

Claims

1. A heat transfer medium comprising a compound (A) represented by the following formula (1): Ａ -O-R １ -O-R Ｂ (1) In formula (1), R Ａ is a perfluoroalkenyl group having 2 to 4 carbon atoms; R Ｂ is a fluoroalkyl group having 2 to 4 carbon atoms or a fluoroalkenyl group having 2 to 4 carbon atoms; R １ is an alkylene group having 1 to 4 carbon atoms.

2. R Ａ 2. The heat transfer medium according to claim 1, wherein in the perfluoroalkenyl group, one of the carbon atoms constituting the carbon-carbon double bond is bonded to an adjacent oxygen atom.

3. R Ｂ 2. The heat transfer medium according to claim 1, wherein the fluoroalkenyl group has one of the carbon atoms constituting a carbon-carbon double bond bonded to an adjacent oxygen atom.

4. R Ｂ The heat transfer medium according to claim 1, wherein is a fluoroalkyl group having one hydrogen atom and having 2 to 4 carbon atoms.

5. The heat transfer medium according to claim 1, wherein compound (A) is 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene, 1,2,3,3,3-pentafluoro-1-[3-(1,1,2,3,3,3-hexafluoropropoxy)propoxy]-1-propene, or 1,2,3,3,4,4,4-heptafluoro-1-[2-(1,1,2,3,3,4,4,4-octafluorobutoxy)ethoxy]-1-butene.

6. The heat transfer medium according to claim 1, wherein the content of compound (A) is 50 mass% or more.

7. The heat transfer medium according to any one of claims 1 to 6, which is used for cooling or heating components in semiconductor manufacturing equipment.

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