Hydrofluoroether composition

Abstract

Provided is a hydrofluoroether (HFE) composition containing 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane (HFE-77-12) as the primary component. This HFE composition is configured such that degradation, etc., of HFE-12 under high-temperature environments is suppressed. This HFE composition contains HFE-77-12 and a stabilizer. The stabilizer is at least one type of compound selected from the group consisting of phenols, ethers, epoxides, amines, alcohols, and hydrocarbons.

Description

Hydrofluoroether composition

[0001] The present invention relates to a hydrofluoroether (HFE) composition useful as a heat transfer medium or the like.

[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, but PFCs have a problem in that they have a high global warming potential (GWP) and have a large impact on the environment due to the greenhouse effect.

[0004] For this reason, the use of HFEs, which have a smaller impact on the environment, has been studied as an alternative heat transfer medium to PFCs (see, for example, Patent Document 1). One known example of an HFE is 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane (hereinafter, sometimes abbreviated as HFE-77-12).

[0005] Special Publication No. 2007-524737

[0006] The above-mentioned fluorine-based heat transfer media such as PFCs and HFEs may be used with the addition of a stabilizer to inhibit decomposition, alteration, and deterioration (hereinafter also referred to as deterioration, etc.).

[0007] However, HFEs have lower thermal stability than PFCs, and are more susceptible to degradation when used continuously as a heat transfer medium in a high-temperature environment, for example, at 200°C. It was not clear what stabilizers would be effective in suppressing the degradation of HFEs in such cases. The type of effective stabilizer varies depending on the type of HFE used, the environment in which it is used, and the conditions of use, and no studies have been conducted to date on stabilizers that can be suitably applied when HFE-77-12 is used as a heat transfer medium.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an HFE composition containing HFE-77-12 as a main component, in which degradation of HFE-77-12 is suppressed even in a high-temperature environment.

[0009] The present invention is based on the discovery of a stabilizer that can suppress the deterioration of HFE-77-12 even in a high-temperature environment.

[0010] The present invention provides the following means. [1] A hydrofluoroether composition comprising 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane and a stabilizer, wherein the stabilizer is at least one compound selected from the group consisting of phenols, ethers, epoxides, amines, alcohols, and hydrocarbons. [2] The hydrofluoroether composition of [1], in which the content of the stabilizer is 0.0001 to 10% by mass. [3] The hydrofluoroether composition of [1] or [2], in which the content of 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane is 70% by mass or more. [4] The hydrofluoroether composition of any of [1] to [3], wherein the stabilizer comprises at least one compound selected from methanol, ethanol, isopropanol, 1,2-butylene oxide, tetrahydrofuran, 1,4-dioxane, 2-methyl-2-butene, 2-methyl-2-pentene, 3-methyl-2-pentene, 2,3-dimethyl-2-butene, 2,4,4-trimethyl-2-pentene, n-heptane, n-butylamine, diisopropylamine, N-methylmorpholine, N-methylpyrrole, 2,6-di-t-butyl-4-methylphenol, and 4-methoxyphenol. [5] The hydrofluoroether composition of any of [1] to [4], wherein the stabilizer has a boiling point of 70 to 280°C. [6] A heat transfer medium which is the hydrofluoroether composition of any of [1] to [5]. [7] The heat transfer medium of [6], which is used for cooling or heating components in semiconductor manufacturing equipment.

[0011] The HFE composition of the present invention can suppress deterioration of the main component HFE-77-12 even in a high-temperature environment, and therefore can be suitably used as a heat transfer medium.

[0012] The HFE composition of an embodiment of the present invention (hereinafter also referred to as this embodiment) contains 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane (hereinafter abbreviated as HFE-77-12) and a stabilizer, wherein the stabilizer is at least one compound selected from the group consisting of phenols, ethers, epoxides, amines, alcohols, and hydrocarbons.

[0013] HFE-77-12 has the chemical formula CF ３ CHFCF ２ OCH ２ CH ２ OCF ２ CHFCF ３ HFE-77-12 has a high boiling point of 164°C, but a freezing point below -100°C, and is liquid over a wide temperature range, making it an excellent heat transfer medium.

[0014] The HFE composition of the present embodiment, which contains HFE-77-12 and the stabilizer, suppresses deterioration of HFE-77-12 even after storage at a high temperature of 200°C for 7 days. That is, the stabilizer is a compound that is effective in suppressing decomposition, alteration, and deterioration accompanied by the generation of fluoride ions from HFE-77-12. Therefore, when used as a heat transfer medium, the HFE composition of the present embodiment can suppress corrosion of metal members and the like of a heat transfer medium circulating device caused by fluoride ions derived from the HFE.

[0015] In this embodiment, when the fluoride ion concentration in the HFE composition after storage at 200° C. for 7 days is less than 10 ppm by mass, it is determined that the deterioration of the HFE composition is sufficiently suppressed, and when the fluoride ion concentration is less than 1 ppm by mass, it is determined that the effect of suppressing deterioration is even greater. Specifically, the fluoride ion concentration is measured by the method described in the Examples.

[0016] The content of the stabilizer in the HFE composition of the present embodiment is 0.0001 to 10% by mass, preferably 0.0001 to 1% by mass, more preferably 0.0005 to 1% by mass, and particularly preferably 0.001 to 0.1% by mass, from the viewpoint of good high-temperature stability of the HFE composition.

[0017] The stabilizer used in the HFE composition of this embodiment is at least one compound selected from the group consisting of phenols, ethers, epoxides, amines, alcohols, and hydrocarbons. It is believed that the stabilizing effect of these compounds on HFE-77-12 varies depending on the type. For example, phenols, alcohols, and hydrocarbons are believed to have the effect of inhibiting the elimination of hydrogen fluoride from HFE-77-12. Epoxides are believed to capture acids and fluoride ions generated by the decomposition of HFE-77-12, while amines are believed to have the effect of neutralizing the generated acids and inhibiting acid-induced degradation. Therefore, these compounds may be used alone, or two or more may be used in combination in consideration of the synergistic effect of the different stabilizing effects of the various compounds. Two or more compounds with similar stabilizing effects may also be used in combination. It is preferable that the stabilizer be soluble in HFE-77-12 from the viewpoint of obtaining an HFE composition with a uniform liquid phase.

[0018] In this embodiment, phenols refer to aromatic hydroxy compounds having one or more hydroxy groups on an aromatic hydrocarbon nucleus. A benzene nucleus is preferred as the aromatic hydrocarbon nucleus. One or more hydrogen atoms bonded to the aromatic hydrocarbon nucleus may be substituted with a halogen atom. The aromatic hydrocarbon nucleus may have one or more substituents bonded thereto in addition to the hydrogen atoms. Examples of the substituent include hydrocarbon groups, alkoxy groups, acyl groups, and carbonyl groups. Examples of the hydrocarbon group include alkyl groups, alkenyl groups, aromatic hydrocarbon groups, and aralkyl groups. Preferred are alkyl groups and alkenyl groups, and more preferably alkyl groups. Of the substituents, alkyl groups, alkenyl groups, alkoxy groups, acyl groups, and carbonyl groups preferably have 6 or fewer carbon atoms, and aromatic hydrocarbon groups and aralkyl groups preferably have 10 or fewer carbon atoms. Furthermore, phenols preferably have an alkyl or alkoxy group at at least one of the ortho and para positions relative to the hydroxy group of the aromatic hydrocarbon nucleus. In this case, a branched alkyl group such as a t-butyl group is preferred as the alkyl group. The aromatic hydrocarbon nucleus may have alkyl groups bonded to both of the two ortho positions relative to the hydroxy group.

[0019] Specific examples of phenols include phenol, 1,2-benzenediol, 1,3-benzenediol, 1,4-benzenediol, 1,3,5-benzenetriol, 2,6-di-t-butyl-4-methylphenol, 2,4,6-tri-t-butylphenol, 2-t-butylphenol, 3-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2,6-di-t-butylphenol, 4,6-di-t-butylphenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, methylphenol, 2,6-dimethylphenol, 2,3,6-trimethylphenol, 2,4,6-trimethylphenol, 2,5,6-trimethylphenol, 3-isopropylphenol, 2-isopropyl-5-methylphenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2-ethoxyphenol, 3-ethoxyphenol, 4-ethoxyphenol, 2-propoxyphenol, 3-propoxyphenol, 4-propoxyphenol, α-tocopherol, β-tocopherol, γ-tocopherol, 4-t-butylcatechol, etc. Of these, phenol, 1,2-benzenediol, 2,6-di-t-butyl-4-methylphenol, m-cresol, 2-isopropyl-5-methylphenol, α-tocopherol, and 4-methoxyphenol are preferred.

[0020] In this embodiment, ethers are linear ethers in which two hydrocarbon groups are bonded to an oxygen atom, or cyclic ethers having an oxygen atom as a ring-constituting atom (excluding epoxides, which are three-membered cyclic ethers). The linear ethers and cyclic ethers may have one or more etheric oxygen atoms. The number of carbon atoms in ethers is preferably 12 or less. Furthermore, the hydrogen atoms of the hydrocarbon groups in the ethers may be substituted with substituents such as halogen atoms or hydroxy groups. However, ethers having an epoxy group are considered to be epoxides.

[0021] Specific examples of ethers include dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, dipentyl ether, diisopentyl ether, diallyl ether, ethyl methyl ether, ethyl propyl ether, ethyl isopropyl ether, ethyl isobutyl ether, ethyl isopentyl ether, ethyl vinyl ether, allyl ethyl ether, ethyl phenyl ether, ethyl naphthyl ether, ethyl propargyl ether, 1,4-dioxane, 1,3-dioxane, 1,3,5-trioxane, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol diphenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol methyl ether, anisole, anethole, trimethoxyethane, triethoxyethane, furan, 2-methylfuran, and tetrahydrofuran. As the ethers, cyclic ethers having 4 to 6 membered rings are preferred, and among these, 1,4-dioxane, 1,3-dioxane, 1,3,5-trioxane, 2-methylfuran, and tetrahydrofuran are preferred.

[0022] In this embodiment, epoxides are compounds having one or more epoxy groups. The number of epoxy groups in the epoxides may be one or more. The number of carbon atoms in the epoxides is preferably 12 or less. The epoxides may also have a substituent such as a halogen atom, an etheric oxygen atom, or a hydroxy group.

[0023] Specific examples of epoxides include 1,2-propylene oxide, 1,2-butylene oxide, 1,2-epoxy-3-phenoxypropane, butyl glycidyl ether, methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, vinyl glycidyl ether, allyl glycidyl ether, diethylene glycol diglycidyl ether, epichlorohydrin, limonene oxide, etc. Of these, 1,2-propylene oxide, 1,2-butylene oxide, and butyl glycidyl ether are preferred.

[0024] In this embodiment, amines are compounds (primary to tertiary amines) having one or more substituted or unsubstituted amino groups. The amines are acyclic amines or cyclic amines in which the nitrogen atom of the amino group is a ring-constituting atom. The group bonded to the nitrogen atom of the secondary amine or tertiary amine is preferably an alkyl group having 6 or less carbon atoms or a hydroxyalkyl group having 6 or less carbon atoms. The number of carbon atoms in the amines is preferably 16 or less, more preferably 10 or less. Examples of acyclic amines include aliphatic amines and aromatic amines. Examples of aromatic amines include benzene nucleus-containing compounds having one or more substituted or unsubstituted amino groups. Examples of cyclic amines include 4- to 6-membered ring compounds having 1 to 3 ring-constituting nitrogen atoms.

[0025] Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, isopropylamine, diisopropylamine, n-butylamine, dibutylamine, tributylamine, isobutylamine, diisobutylamine, sec-butylamine, t-butylamine, pentylamine, dipentylamine, tripentylamine, hexylamine, 2-ethylhexylamine, allylamine, diallylamine, triallylamine, aniline, N-methylaniline, N,N-dimethylaniline, N,N-diethylamine, N,N-diethylamine, N-methylaniline, N,N-dimethylaniline, N,N-diethylamine, N-methylaniline, N,N-dimethylaniline, N-methyl ... Examples of suitable amines include ethylaniline, pyridine, picoline, morpholine, N-methylmorpholine, benzylamine, dibenzylamine, α-methylbenzylamine, propylenediamine, diethylhydroxyamine, pyrrole, N-methylpyrrole, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, ethanolamine, diethanolamine, triethanolamine, propanolamine, dipropanolamine, isopropanolamine, diisopropanolamine, N-methylethanolamine, N,N-dimethylethanolamine, N-ethylmorpholine, diphenylamine, ethylenediamine, etc. Preferred amines are alkylamines and cyclic amines, and among these, preferred are pyrrole, N-methylpyrrole, 2-methylpyridine, n-propylamine, diisopropylamine, n-butylamine, N-methylmorpholine, and N-ethylmorpholine.

[0026] The alcohols in this embodiment are compounds in which one or more hydroxy groups are bonded to a hydrocarbon having a chain or cyclic structure, preferably one hydroxy group.

[0027] Specific examples of alcohols include methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 1-ethyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, 1 Examples of alcohols include α-nonanol, 3,5,5-trimethyl-1-hexanol, 1-decanol, 1-undecanol, 1-dodecanol, allyl alcohol, benzyl alcohol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, α-terpineol, 2,6-dimethyl-4-heptanol, nonyl alcohol, tetradecyl alcohol, and 2-propyn-1-ol. Preferred alcohols are linear or branched chain alcohols having 1 to 3 carbon atoms, and among these, methanol, ethanol, isopropanol, and 2-propyn-1-ol are preferred.

[0028] In this embodiment, hydrocarbons are compounds having carbon atoms and hydrogen atoms in a chain or cyclic structure. The hydrocarbons may be saturated hydrocarbons or unsaturated hydrocarbons in which at least one carbon-carbon bond is unsaturated. The hydrocarbons preferably have 5 to 9 carbon atoms.

[0029] Specific examples of saturated hydrocarbons include n-pentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, n-heptane, 2-methylhexane, 3-methylhexane, 2,4-dimethylpentane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2,2-dimethylhexane, 2,5-dimethylhexane, 3,3-dimethylhexane, 2-methyl-3-ethylpentane, 3-methyl-3-ethylpentane, 2,3,3-trimethylpentane, 2,3,4-trimethylpentane, 2,2,3-trimethylpentane, 2-methylheptane, 2,2,4-trimethylpentane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, etc. Of these, n-pentane, cyclopentane, n-hexane, cyclohexane, and n-heptane are preferred.

[0030] Specific examples of unsaturated hydrocarbons include pentene isomers such as 1-pentene, 2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, and 2-methyl-2-butene, 1-hexene, 2-hexene, 3-hexene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-butene, 3-ethyl-1-butene, 3-ethyl-2-butene, and 2-methyl-2-butene. Hexene isomers such as pentene, 3-methyl-2-pentene, 4-methyl-2-pentene, and 2,3-dimethyl-2-butene, heptene isomers such as 1-heptene, 2-heptene, 3-heptene, 4-heptene, and 3-ethyl-2-pentene, octene isomers such as 1-octene, 2,4,4-trimethyl-1-pentene, and 2,4,4-trimethyl-2-pentene, and nonene isomers such as 1-nonene. Further examples include diene compounds such as butadiene, isoprene, hexadiene, heptadiene, and octadiene; and unsaturated cyclic hydrocarbons such as cyclohexene, cyclohexadiene, cycloheptene, cycloheptadiene, cyclooctene, and cyclooctadiene. Of these, 2-methyl-2-butene, 2-methyl-1-pentene, 2-methyl-2-pentene, 3-methyl-2-pentene, 3-ethyl-2-butene, 2,3-dimethyl-2-butene, 2,4,4-trimethyl-1-pentene, and 2,4,4-trimethyl-2-pentene are preferred.

[0031] In this embodiment, the stabilizer is preferably one that easily coexists with HFE-77-12 in the liquid phase, from the viewpoint of good stability when the HFE composition is used as a liquid medium for various applications. Furthermore, from the viewpoint of low volatility, at least one compound preferably has a boiling point of 70 to 280°C, more preferably 75 to 270°C, and even more preferably 80 to 265°C. The boiling point referred to in this specification is the boiling point at 0.101 MPa (1 atm).

[0032] In view of the stability of the HFE composition at 200°C, preferred stabilizers in the present embodiment include methanol, ethanol, isopropanol, 1,2-butylene oxide, tetrahydrofuran, 1,4-dioxane, 2-methyl-2-butene, 2-methyl-2-pentene, 3-methyl-2-pentene, 2,3-dimethyl-2-butene, 2,4,4-trimethyl-2-pentene, n-heptane, n-butylamine, diisopropylamine, N-methylmorpholine, N-methylpyrrole, 2,6-di-t-butyl-4-methylphenol, and 4-methoxyphenol. Among these, from the viewpoint of the boiling point of the compound, ethanol, isopropanol, 1,4-dioxane, 3-methyl-2-pentene, 2,4,4-trimethyl-2-pentene, n-heptane, n-butylamine, diisopropylamine, N-methylmorpholine, N-methylpyrrole, 2,6-di-t-butyl-4-methylphenol, and 4-methoxyphenol are more preferred. These may be used alone or in combination of two or more.

[0033] When two or more compounds are used in combination as stabilizers, taking into consideration the synergistic effect of compounds with different stabilizing actions as described above, examples of the combination include unsaturated hydrocarbons and alcohols, unsaturated hydrocarbons, alcohols and amines, unsaturated hydrocarbons, alcohols and phenols, etc. Two or more compounds with similar stabilizing actions may be used in combination.

[0034] The content of HFE-77-12 in the HFE composition of this embodiment is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more, from the viewpoint of fully exhibiting the properties of HFE-77-12 itself. When the HFE composition of this embodiment is used as a heat transfer medium, the content of HFE-77-12 is preferably 98.0% by mass or more, more preferably 99.0% by mass or more, and even more preferably 99.9% by mass or more, from the viewpoint of allowing HFE-77-12 itself to exhibit its favorable properties as a heat transfer medium.

[0035] When the HFE composition of the present embodiment is used as a heat transfer medium, from the viewpoint of stably exhibiting the properties of HFE-77-12 as a heat transfer medium, the total content of HFE-77-12 and the stabilizer is preferably 99.0% by mass or more, more preferably 99.5% by mass or more, and particularly preferably 100% by mass.

[0036] The HFE composition of this embodiment may consist only of HFE-77-12 and a stabilizer, or may contain components other than HFE-77-12 and the stabilizer (for example, a fluorine-based solvent, etc.) according to various purposes such as improving various properties, within a range that does not impair the effects of the present invention. When the HFE composition contains a fluorine-based solvent, the content thereof is preferably less than 30% by mass, more preferably less than 20% by mass, even more preferably less than 15% by mass, and still more preferably less than 10% by mass.

[0037] Examples of fluorine-based solvents include Galden (registered trademark) HT90 / 110 / 135 / 150 / 200 (all CF ３ - [OCF (CF ３ ) (CF ２ ) ｎ (OCF ２ ) ｍ ]-CF ３ ), ZV90, SVX, ZT-180; FTM-110 / 135 / 150 / 170 / 200 / 230 / 270 manufactured by Sanming Hexafluo Chemicals; Fluorinert (registered trademark) FC-75 (C ８ F ８ ) / 3283 ((C ３ F ７ ) ３ N) / 40 ((C ４ F ９ ) ３ N) / 43 ((C ４ F ９ ) ３ N) / 70 ((C ５ F １１ ) ３ N), FX-3300(C ８ F ８ ), Novec 7100 (CF ３ (CF ２ ) ３ OCH３ and (CF ３ ) ２ CFCF ２ OCH ３ Mixture of CF ３ (CF ２ ) ３ O.C. ２ H ５ and (CF ３ ) ２ CFCF ２ O.C. ２ H ５ Mixture of CF ３ ) ２ CFCF (CF ２ CF ３ ) OCH ３ ) / 7500 (CF ３ CF ２ CF ２ CF (OCH ２ CH ３ )CF(CF ３ )CF ３ ) / 7600 (CF ３ CFHCF ２ OC (CH ３ )CF ２ CFHCF ３ ); Opteon (registered trademark) SF10 / 30 (CF ３ CH=CHCF ３ and CClH = CClH mixture) / 33(CF ３ CH=CHCF ３ ) / 2P50; Asahiklin (registered trademark) AC-2000 (CF ３ CF ２ CF ２ CF ２ CF ２ CF ２ H) / 6000(CF ３ CF ２ CF ２ CF ２ CF ２ CF ２ CH ２ CH ３ ), Amorea (registered trademark) AS-300 (CF ２ HCF = CClH); CELEFIN (registered trademark) 1233Z (CF ３Examples of commercially available products include DAISAVE (registered trademark) SS-54 manufactured by Daikin Industries, Ltd. and HFE-65-12 manufactured by Daikin Technology Co., Ltd.

[0038] The HFE composition of this embodiment is obtained by mixing HFE-77-12 and a stabilizer. The methods for producing HFE-77-12 and the stabilizer are not particularly limited. HFE-77-12 can be synthesized by a known method, such as an addition reaction of hexafluoropropene with ethylene glycol in the presence of an alkali catalyst such as potassium carbonate. Specifically, it can be produced by the method described in the following examples. Commercially available compounds can be used as the stabilizer.

[0039] The HFE composition of this embodiment has a small GWP and can therefore be suitably used in a wide range of applications, such as a cleaning agent, solvent, foaming agent, aerosol, working medium for binary power generation such as heat pipes and factory waste heat recovery, storage liquid for electronic components, and medium for gross leak tests, thermal shock tests, liquid burn-in tests, and voltage resistance tests of electronic components. Specifically, as a cleaning agent, the composition can also be used to remove contaminants (e.g., reaction products such as silicon oxides generated during the etching process) deposited inside the chamber of a dry etching apparatus used in semiconductor manufacturing.

[0040] Furthermore, as described above, since deterioration is suppressed even at a high temperature of 200°C, the HFE composition can be suitably used as a heat transfer medium. Examples of heat transfer mediums include those used for controlling the temperature of wafers in semiconductor manufacturing, cooling and heating semiconductor elements and electronic components, cooling servers, heat pumps, heat pipes, thermostatic baths, etc. The HFE composition of this embodiment is suitable as a heat transfer medium for cooling or heating components in semiconductor manufacturing equipment, and is also suitable as a heat transfer medium used continuously under harsh conditions of a high electric field and a high-temperature environment, such as in a dry etching process using thermal plasma in semiconductor manufacturing.

[0041] The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples. The reaction product was identified by proton nuclear magnetic resonance ( １H 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.)).

[0042] [Synthesis of HFE-77-12] 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 mixture was kept sealed 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 reaction crude liquid in the autoclave was recovered by filtration. The recovered reaction crude liquid contained 45% by mass of HFE-77-12. 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 crude reaction 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-77-12.

[0043] [Preparation of HFE Compositions] A stabilizer shown in each example in Table 1 was added to the HFE-77-12 synthesized above to give a predetermined concentration to prepare 100 g of each HFE composition. Example 1 is a comparative example in which no stabilizer was added. Examples 2 to 29 are examples in which one type of compound was added as a stabilizer, and Examples 30 to 34 are examples in which two or more types of compounds were added as stabilizers.

[0044] [High-Temperature Stability Test] Each prepared HFE composition was placed in a stainless steel pressure vessel and stored at 200°C for 7 days to conduct a stability test. The fluoride ion concentration in the HFE composition before the start of the test (immediately after preparation) and after the test was measured using an ion chromatograph ("ICS-1000"; an anion analysis column "Dionex (registered trademark) IonPac (registered trademark) AS12A", manufactured by Thermo Fisher Scientific Inc.). The high-temperature stability of the HFE composition was evaluated according to the increase in fluoride ion concentration after the test, using the following evaluation criteria. The evaluation results are shown in Table 1. <Evaluation criteria> A: Less than 1 ppm by mass B: 1 ppm by mass or more and less than 10 ppm by mass C: 10 ppm by mass or more

[0045]

[0046] The results shown in Table 1 confirm that when a stabilizer was added (Examples 2 to 34), the generation of fluoride ions due to the decomposition of HFE-77-12 was suppressed, and the stability at a high temperature of 200° C. was high. Furthermore, a comparison of Examples 3 to 7 and a comparison of Examples 13 to 17 indicates that the stability of the HFE composition is higher when the concentration of the stabilizer in the HFE composition is 0.001 to 0.1 mass %.

Claims

1. A hydrofluoroether composition comprising 1,1,1,2,3,3 - hexafluoro - 3 - [2 - (1,1,2,3,3,3 - hexafluoropropoxy)ethoxy]propane and a stabilizer, wherein the stabilizer is at least one compound selected from the group consisting of phenols, ethers, epoxides, amines, alcohols and hydrocarbons.

2. The hydrofluoroether composition according to claim 1, wherein the content of the stabilizer is 0.0001 to 10% by mass.

3. The hydrofluoroether composition according to claim 1, wherein the content of 1,1,1,2,3,3 - hexafluoro - 3 - [2 - (1,1,2,3,3,3 - hexafluoropropoxy)ethoxy]propane is 70% by mass or more.

4. The hydrofluoroether composition according to claim 1, wherein the stabilizer contains at least one compound selected from methanol, ethanol, isopropanol, 1,2 - butylene oxide, tetrahydrofuran, 1,4 - dioxane, 2 - methyl - 2 - butene, 2 - methyl - 2 - pentene, 3 - methyl - 2 - pentene, 2,3 - dimethyl - 2 - butene, 2,4,4 - trimethyl - 2 - pentene, n - heptane, n - butylamine, diisopropylamine, N - methylmorpholine, N - methylpyrrole, 2,6 - di - t - butyl - 4 - methylphenol, and 4 - methoxyphenol.

5. The hydrofluoroether composition according to claim 1, wherein the boiling point of the stabilizer is 70 to 280°C.

6. A heat transfer medium which is the hydrofluoroether composition according to any one of claims 1 to 5.

7. The heat transfer medium according to claim 6, which is used for cooling or heating components in a semiconductor manufacturing apparatus.

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