Hydrofluoroether composition

Abstract

To provide a hydrofluoroether composition capable of suppressing the formation of an acid component even at a high temperature (for example, 90°C or higher). The hydrofluoroether composition contains 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy ]propane and 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy ]-1-propene, and the content of 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy ]-1-propene is from 0.0001 mass% to less than 2.0000 mass%.

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, as heat transfer media to replace PFCs has been studied (see, for example, Patent Document 1). However, HFEs have lower thermal stability than PFCs, and when used continuously as heat transfer media, they decompose and desorb to produce acids such as hydrogen fluoride, which may cause corrosion and deterioration of heat transfer media circulating devices and the like, and ultimately lead to breakdowns.

[0005] As a means for suppressing the decomposition of a fluorine-based heat transfer medium, it is known to add a known stabilizer such as a phenol compound, an aromatic compound containing an unsaturated hydrocarbon group, an aromatic amine compound, an aromatic thiazine compound, a terpene compound, a quinone compound, a nitro compound, an epoxy compound, or an orthoester compound (see, for example, Patent Document 2).

[0006] Patent Publication No. 2007-524737 International Publication No. 2016 / 181910

[0007] However, for example, in a dry etching process using thermal plasma in semiconductor manufacturing, if a heat transfer medium in which a known stabilizer has been added to HFE is used under harsh conditions of a high electric field and a high temperature environment (e.g., 90°C or higher), a part of the heat transfer medium may decompose, and the desired properties (e.g., high insulating properties) may not be fully exhibited.

[0008] For this reason, there has been a demand for a heat transfer medium using an HFE that can suppress the generation of acids from the heat transfer medium over time without using a large amount of conventional stabilizers, and that can be used stably and continuously as a heat transfer medium.

[0009] The present invention has been made in view of the above circumstances, and has as its object to provide an HFE composition that can suppress the generation of acids even at high temperatures, for example, at 90°C or higher.

[0010] The present invention is based on the discovery that by combining a specific HFE with a specific compound, the generation of acid components can be suppressed even after exposure to high temperatures of, for example, 90° C. or higher for several days.

[0011] The present invention provides the following means: [1] A hydrofluoroether composition containing 1,1,1,2,3,3-hexafluoro-3-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]propane and 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene, in which the content of 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene is 0.0001% by mass or more and less than 2.0000% by mass. [2] The hydrofluoroether composition of [1], wherein the content of 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene is 0.0001% by mass or more and 1.0000% by mass or less. [3] A heat transfer medium which is the hydrofluoroether composition of [1] or [2]. [4] The heat transfer medium of [3], which is used for cooling or heating components in semiconductor manufacturing equipment.

[0012] The HFE composition of the present invention can suppress the generation of acids even at high temperatures, for example, at or above 90° C. Therefore, the HFE composition of the present invention can be used stably and continuously as a heat transfer medium.

[0013] 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 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene, and the content of 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene is 0.0001% by mass or more and less than 2.0000% by mass.

[0014] 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.

[0015] 1,2,3,3,3-Pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene has the chemical formula CF ３ CF = CFOCH ２ CH ２ OCF ２ CHFCF ３ and is a compound having a structure in which hydrogen fluoride has been eliminated from a fluoroalkyl group bonded to one etheric oxygen atom of HFE-77-12 (hereinafter referred to as the HF-free compound).

[0016] The HFE composition of the present embodiment, which contains HFE-77-12 and a trace amount of 0.0001 mass % or more and less than 2.0000 mass % (1 mass ppm or more and less than 20,000 mass ppm) of a dehydrogenated product, can suppress the generation of acids even when exposed to high temperatures of 90°C or more, and even 150°C, for several days.

[0017] The reason why acid generation is suppressed is not clear, but it is presumed that even if HFE-77-12 decomposes at high temperatures to generate acids such as hydrogen fluoride, the acid is captured by a trace amount of the HF-free product in the HFE composition. When hydrogen fluoride is added to the HF-free product, HFE-77-12 is formed. Therefore, even if the HF-free product captures acids, it does not produce products with significantly different structures that would significantly change the properties of the HFE composition as a heat transfer medium, and is therefore thought to be able to act as a stabilizer for HFE-77-12. Therefore, when used as a heat transfer medium, the HFE composition of the present embodiment can suppress corrosion of metal components, etc., of a heat transfer medium circulating device due to acids derived from the HFE.

[0018] The content of the HF-free product in the HFE composition of this embodiment is from 0.0001% by mass to less than 2.0000% by mass (from 1 ppm by mass to less than 20,000 ppm by mass), preferably from 0.0001% by mass to 1.0000% by mass (from 1 ppm by mass to 10,000 ppm by mass), and more preferably from 0.0010% by mass to 0.1,000% by mass (from 10 ppm by mass to 1,000 ppm by mass).

[0019] By having the HF-free product content of 1 ppm by mass or more, the generation of acids in the HFE composition can be effectively suppressed, but if the HF-free product content is too high, it is undesirable because it may impair the properties of HFE-77-12 itself as a heat transfer medium. In other words, if the HF-free product content is 2.0000% by mass or more, the generation of acids in the HFE composition cannot be sufficiently suppressed. The reason for this is not clear, but it is thought that if the HF-free product content is too high, the acid scavenging capacity is exceeded, and acids may be generated due to decomposition of the HF-free product itself, etc.

[0020] The content of HFE-77-12 in the HFE composition of this embodiment is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and still more preferably 80% by mass or more. When the HFE composition of this embodiment is used as a heat transfer medium, from the viewpoint of enabling HFE-77-12 itself to exhibit good properties as a heat transfer medium, the content of HFE-77-12 in the HFE composition of this embodiment is preferably more than 98.0000% by mass and 99.9999% by mass or less, more preferably 99.0000% by mass or more and 99.9990% by mass or less, and even more preferably 99.9000% by mass or more and 99.9990% by mass or less.

[0021] 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 HF-free product is preferably 99.0000% by mass or more, more preferably 99.5000% by mass or more, and particularly preferably 100% by mass.

[0022] The HFE composition of this embodiment may consist only of HFE-77-12 and the HF-free product, or may contain components other than HFE-77-12 and the HF-free product (for example, a fluorinated solvent) for various purposes such as improving various properties, within a range that does not impair the effects of the present invention. When the HFE composition of this embodiment contains a fluorinated solvent, the content thereof is preferably less than 70% by mass, more preferably less than 50% by mass, even more preferably less than 30% by mass, and still more preferably less than 20% by mass.

[0023] Examples of fluorine-based solvents include Galden (registered trademark) HT90 / 110 / 135 / 150 / 170 / 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 OCH ３ 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 (CF３ 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 Examples of commercially available products include Cerefin (registered trademark) 1233Z (HCFO-1233zd(Z)) / CGS-5E manufactured by Central Glass Co., Ltd.; DAISAVE (registered trademark) SS-54 manufactured by Daikin Industries, Ltd.; and HFE-65-12 manufactured by Chukyoshin Co., Ltd.

[0024] The HFE composition of this embodiment is obtained by mixing HFE-77-12 and the HF-free derivative. The methods for producing HFE-77-12 and the HF-free derivative 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. The HF-free derivative can be synthesized by a method in which HFE-77-12 is reacted in the presence of a strong base such as an alkali metal alkoxide to eliminate hydrogen fluoride. Specifically, HFE-77-12 and the HF-free derivative can be produced by the methods described in the following examples.

[0025] Because the HFE composition of this embodiment has a small GWP, it can be suitably used in a wide range of applications, including as a cleaning agent, solvent, foaming agent, aerosol, working fluid for binary power generation such as heat pipes and factory exhaust heat recovery, storage liquid for electronic components, and medium for gross leak testing, thermal shock testing, liquid burn-in testing, and voltage resistance testing of electronic components. Furthermore, as described above, since the HFE composition can suppress acid generation even at high temperatures of 90°C or higher, it can be suitably used as a heat transfer medium. Examples of heat transfer mediums include those used for wafer temperature control in semiconductor manufacturing, cooling and heating of semiconductor elements and electronic components, cooling of servers, heat pumps, heat pipes, and thermostatic baths. 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 high electric fields and high-temperature environments, such as in dry etching processes using thermal plasma in semiconductor manufacturing. Furthermore, as described above, the HFE composition of this embodiment can also be suitably used as a cleaning agent. Specifically, it can also be used to remove contaminants (reaction products such as silicon oxides that are produced during the etching process) that accumulate inside the chamber of a dry etching device used 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. The reaction product was 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.)).

[0027] [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 and 4.5% by mass of the HF-depleted product. 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.

[0028] [Synthesis of HF-free product] 117 g of tert-butyl alcohol (manufactured by Kanto Chemical Co., Inc.) and 75 g of HFE-77-12 were placed in a glass reactor (internal volume: 0.5 liters) equipped with a stirrer, and the mixture was 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. The mixture was maintained at 40°C for 2 hours to allow the reaction to proceed, and the reaction crude liquid was neutralized with a 10% by mass aqueous potassium bicarbonate solution and washed with water. The organic layer was recovered and purified by distillation to obtain a HF-free product.

[0029] Examples 1 to 6 Preparation of HFE Compositions Compositions 1 to 6 were prepared by mixing the HFE-77-12 synthesized above and the HF-free product in the proportions shown in each example in Table 1.

[0030] [High-Temperature Stability Test] Each of the HFE compositions (Compositions 1 to 6) in Examples 1 to 6 was evaluated by the following high-temperature stability test. 100 g of the HFE composition was placed in a polytetrafluoroethylene (PTFE) container containing a general-purpose cold-rolled steel plate (SPCC) test piece (25 mm x 30 mm, 2 mm thick), and the test piece was immersed and stored at 100°C or 150°C for 7 days. After the test, the appearance of the test piece was visually observed, and the high-temperature stability of the HFE composition (presence or absence of acid generation) was evaluated according to the following evaluation criteria. The results are shown in Table 1. <Evaluation Criteria> A: No change B: Loss of surface gloss C: Rust on part of the surface D: Rust on the entire surface In the cases of ratings A and B, no rust was observed on the test piece, and it was considered that acid generation from the HFE composition was suppressed. In the cases of ratings C and D, rust was observed on the test piece, and it was considered that the HFE composition generated acid at high temperatures.

[0031]

[0032] From the results shown in Table 1, when the HFE composition does not contain a HF-free compound and contains 100% HFE-77-12 by mass (Example 1), acids are likely to be generated at high temperatures of 100°C or higher, and it is presumed that in HFE compositions (Examples 2 to 5) in which the HF-free compound content is 0.0001% by mass or higher but less than 2.0000% by mass (1 ppm by mass or higher but less than 20,000 ppm by mass), the acid scavenging effect of the HF-free compound suppresses the generation of acids including hydrogen fluoride. When the HF-free compound content in the HFE composition is 2.0000% by mass (Example 6), it is presumed that at a high temperature of 150°C, the HF-free compound underwent thermal decomposition, exceeding its ability to scavenge acid, causing the HFE composition to generate acids.

[0033] It was confirmed that the HFE composition of Example 4 could be used without any problems even when circulated as a heat transfer medium at a controlled temperature of 100°C for 100 hours in a semiconductor manufacturing apparatus equipped with a mechanism for circulating a heat transfer medium to transfer heat.

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 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene, in which the content of 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene is 0.0001% by mass or more and less than 2.0000% by mass.

2. The hydrofluoroether composition according to claim 1, wherein the content of 1,2,3,3,3-pentafluoro-1-[2-(1,1,2,3,3,3-hexafluoropropoxy)ethoxy]-1-propene is 0.0001% by mass or more and 1.0000% by mass or less.

3. A heat transfer medium which is the hydrofluoroether composition according to claim 1 or 2.

4. The heat transfer medium according to claim 3, which is used for cooling or heating components in semiconductor manufacturing equipment.

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