Fluorine-based solvent composition

Abstract

The purpose of the present invention is to provide a novel composition that can be used in a wide range of applications. Provided is an azeotropic composition or azeotropic-like composition comprising perfluoroheptene and chloroform.

Description

Fluorine-based solvent compositions

[0001] This invention relates to an azeotropic composition or azeotropic-like composition comprising perfluoroheptene and chloroform. It also relates to a method for efficiently removing chloroform contained in perfluoroheptene by utilizing the properties of forming an azeotropic composition or azeotropic-like composition.

[0002] In many industries, fluorinated solvents, including halogenated hydrocarbons such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs), have been used in a wide range of applications, including aerosol propellants, refrigerants, solvents, cleaning agents, foaming agents for thermoplastics and thermosetting foams, heat transfer fluids, gaseous dielectrics, fire extinguishing and suppressing agents, power cycle working fluids, polymerization media, particulate removal fluids, carrier fluids, buffing abrasives, and displacement drying agents.

[0003] However, CFCs and HCFCs are known as ozone-depleting substances, and HCFCs, in particular, represented by HCFC-225, have been widely used due to their excellent non-flammability, polymer compatibility, and stability. However, because HCFCs have an ozone depletion potential (ODP) and a high global warming potential, they were phased out completely in 2019. On the other hand, while HFCs do not pose a risk of ozone depletion, they contribute to global warming as greenhouse gases, so there is a demand for alternatives with a lower environmental impact, that is, those with an ODP of 0 and a very low global warming potential.

[0004] Perfluoroheptene (PFH), which is one of the non-cyclic perfluoroolefins, is expected to be a next-generation solvent due to its environmental characteristics of having an ozone depletion potential (ODP) of 0 and a global warming potential (GWP) of less than 5. PFH is used in various applications such as various cleaning, heat transfer media, dilution / dispersion solvents, etc. In addition, it is known to be used as one of the components constituting a gas separation membrane made of a polymer (Patent Document 1), or as one of the components constituting an elastomer (Patent Document 2), etc. However, since its boiling point is somewhat high at 71 °C, it is not suitable for applications such as boiling immersion cooling, for example, and it cannot necessarily be used in all applications. Also, it is known that its ability to clean general greases is not high. On the other hand, chloroform has a boiling point of 62 °C, is suitable for applications of boiling immersion cooling, and is excellent in cleaning general greases. However, it is known to have a problem that it cannot be used in many products containing polymers as a cleaning agent because of its strong polymer attack property (causing polymer cloudiness, cracking, dissolution, etc.). Also, it is known to be highly toxic (for example, Non-Patent Document 1).

[0005] Also, when used as a cleaning agent or the like, an azeotropic composition having a constant boiling point characteristic of not being fractionated during use or during distillation at the time of recovery, that is, not being fractionated during boiling / evaporation, is known to be useful (for example, Patent Documents 3, Patent Documents 4, Patent Documents 5). However, as also described in Patent Document 6, it is impossible to theoretically predict whether an azeotropic composition will be formed, and the search for new azeotropic compositions having excellent characteristics continues for various combinations.

[0006] Japanese Patent Application Laid-Open No. 60-099326 Japanese Patent Application Laid-Open No. 1-266119 Japanese Patent Application Laid-Open No. 6-501949 Japanese Patent Application Laid-Open No. 201-514444 Japanese Patent Application Laid-Open No. 2012-528922 Japanese Patent Application Laid-Open No. 2017-110035

[0007] https: / / www.cerij.or.jp / evaluation_document / yugai / 67_66_3.pdf (CERI Hazardousness Evaluation Report)

[0008] The present invention aims to provide a novel azeotropic composition or azeotropic-like composition that can be used in a wide range of industrial applications and solves the above-mentioned problems.

[0009] The inventors have discovered that a composition containing PFH, which has an ODP of 0 and a low global warming potential, and chloroform, which has excellent oil removal properties, is a composition that is highly safe, environmentally friendly, and has excellent polymer compatibility (suppressed polymer attack), and that it forms an azeotropic composition or azeotropic-like composition that behaves similarly to a single compound, thus completing the present invention. The present invention also relates to a method for efficiently removing chloroform contained in PFH by utilizing the formation of an azeotropic composition or azeotropic-like composition.

[0010] In other words, the present invention is characterized by the following: [1] an azeotropic composition or azeotropic-like composition comprising perfluoroheptene and chloroform. [2] the azeotropic composition or azeotropic-like composition according to [1], wherein the perfluoroheptene is 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoro-3-heptene and / or 1,1,1,2,3,4,4,5,5,6,6,7,7,7-tetradecafluoro-2-heptene. [3] the azeotropic composition or azeotropic-like composition according to [1] or [2], comprising 15 to 85% by mass of perfluoroheptene and 85 to 15% by mass of chloroform. [4] A method for removing chloroform from a composition containing perfluoroheptene and chloroform by azeotropic distillation, comprising: allowing the composition containing perfluoroheptene and chloroform to stand at a low temperature to separate it into two phases; recovering the perfluoroheptene phase; and distilling the perfluoroheptene phase. [5] The removal method according to [4], wherein the low temperature is -30 to 20°C.

[0011] According to the present invention, it is possible to provide a composition with an ODP of 0 and a very low global warming potential. The azeotropic composition or azeotropic-like composition of the present invention is a composition containing PFH and chloroform, which has excellent oil removal properties, and is a composition that is highly safe, environmentally friendly, and has excellent polymer compatibility (suppressed polymer attack). The present invention also provides an azeotropic composition or azeotropic-like composition that behaves similarly to a single compound and has the advantage of being non-flammable.

[0012] The boiling curve of the PFH and chloroform composition is shown. The purification results of PFH by distillation of the PFH phase recovered after standing and storing the PFH and chloroform composition (3% by mass: 97% by mass) overnight at 20°C are shown. A schematic diagram of a Soxhlet extraction apparatus is shown.

[0013] The present invention will now be described in detail. The azeotropic composition or azeotropic-like composition of the present invention consists of PFH and chloroform.

[0014] The PFH used in the azeotropic composition or azeotropic-like composition of the present invention is not particularly limited in terms of its structural isomers or stereoisomers, and may be a single isomer or a mixture thereof. Preferred examples of PFH include 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoro-3-heptene (perfluoro-3-heptene), 1,1,1,2,3,4,4,5,5,6,6,7,7,7-tetradecafluoro-2-heptene (perfluoro-2-heptene), and at least one selected from their isomers. More preferably, cis-perfluoro-3-heptene, trans-perfluoro-3-heptene, or a mixture containing these.

[0015] There are no particular restrictions on the chloroform, which is the other component of the azeotropic composition or azeotropic-like composition of the present invention; commercially available chloroform can be used.

[0016] As recognized in the art, an azeotropic composition is a mixture of two or more different components that, when in liquid form under a given pressure, boils at a substantially constant temperature, which is either higher or lower than the boiling point of the individual components, and provides a vapor composition that is essentially identical to the overall liquid composition in boiling (see, for example, M.F. Doherty and M.F. Malone, *Conceptual Design of Distillation Systems*, McGraw-Hill (New York), 2001, pp. 185-186, 351-359).

[0017] At this time, when the composition of the mixed liquid is varied in various ways and the constant-pressure gas-liquid equilibrium relationship is measured, it is known that the boiling point is either maximum or minimum at the composition that forms an azeotropic composition.

[0018] Therefore, the essential characteristics of an azeotropic composition are that, at a given pressure, the boiling point of the liquid composition is fixed, and the composition of the gas phase of the boiling composition is essentially the same as the composition of the liquid phase of the boiling composition (i.e., no fractional distillation of the components of the liquid composition occurs). It is also recognized in the art that when an azeotropic composition is subjected to boiling at different pressures, both the boiling point and the mass percentage of each component of the azeotropic composition may change. Therefore, an azeotropic composition may be defined in terms of the specific relationships that exist between the components, the compositional range of the components, or the precise mass percentage of each component of the composition characterized by its fixed boiling point at a specified pressure.

[0019] The "azeotropic composition" of the present invention is preferably a composition that behaves like an azeotropic composition (i.e., has a constant boiling point characteristic or tends not to fractionally distill during boiling or evaporation), meaning that the composition of the liquid phase and the composition of the gas phase are very close, and changes over time are unlikely to occur. Preferably, the temperature difference between the liquid phase temperature and the gas phase temperature under a given pressure in the gas-liquid equilibrium curve is 2°C or less. More preferably, it is 1°C or less, and even more preferably 0.5°C or less. This is in contrast to non-azeotropic compositions, in which the gas-liquid composition changes to a considerable extent during boiling or evaporation.

[0020] The azeotropic composition or azeotropic-like composition of the present invention comprising PFH and chloroform preferably has a boiling point in the range of 49 to 60°C, preferably 49 to 55°C, and more preferably 50 to 53°C under atmospheric pressure.

[0021] In the present invention, the amount of chloroform relative to PFH that forms the azeotropic composition or azeotropic-like composition is preferably PFH:chloroform = 15-85:85-15% by mass, and more preferably 15-50:50-15% by mass. When using an azeotropic composition or azeotropic-like composition for PFH purification, it is preferable that the amount of PFH in the azeotropic composition or azeotropic-like composition be small. If the amount of PFH is less than 15% by mass (i.e., if the amount of chloroform is too large relative to PFH), an increase in polymer attack may occur, but conversely, if the amount of chloroform is less than 15% by mass (i.e., if the amount of chloroform is too small relative to PFH), an azeotropic composition or azeotropic-like composition will not be formed, making it difficult to purify PFH.

[0022] The azeotropic composition or azeotropic-like composition of the present invention may optionally contain one or more nitroalkanes, epoxides, furans, benzotriazoles, phenols, amines, or phosphates as stabilizers, the amount of which is 0.01 to 5.00% by mass, preferably 0.05 to 0.50% by mass, relative to the composition.

[0023] The azeotropic composition or azeotropic-like composition of the present invention may also optionally contain other components such as alcohols, ketones, ethers, esters, hydrocarbons, glycol ethers, and siloxanes, as long as they do not impair the characteristics of the present invention.

[0024] The azeotropic composition or azeotropic-like composition of the present invention has an ozone depletion potential (ODP) of 0 and a global warming potential (GWP) of about 100 or less, preferably 50 or less, and more preferably 10 or less. Here, ODP and GWP in the present invention are defined in the World Meteorological Organization report, "Scientific Assessment of Ozone Depletion, 2002".

[0025] The azeotropic composition or azeotropic-like composition of the present invention can be used in a wide range of applications where halogenated hydrocarbons have conventionally been used, such as aerosol propellants, refrigerants, solvents, cleaning agents, particulate matter removal fluids, foaming agents (foam expanders) for thermoplastics and thermosetting foams, heat transfer fluids, gaseous dielectrics, fire extinguishing and fire suppression agents, power cycle working fluids, polymerization media, carrier fluids, buffing abrasives, and displacement drying agents.

[0026] When using the present invention as a cleaning agent, the objects to be cleaned with the azeotropic composition or azeotropic-like composition of the present invention are not particularly limited, but it can be suitably used for electronic, electrical, and mechanical parts, or small automobile parts, or other items that are to be continuously produced and cleaned. In particular, the azeotropic composition or azeotropic-like composition of the present invention can be suitably used as a cleaning agent for cleaning solid surfaces having organic (oil) or inorganic contaminants on their surface, such as semiconductor surfaces, electronic substrate surfaces, electronic circuits, CMOS (Complementary Metal Oxide Semiconductor), MEMS (Micro Electro Mechanical Systems), hard disk surfaces, and other surfaces having microstructures.

[0027] In particular, the azeotropic composition or azeotropic-like composition of the present invention is highly safe, environmentally friendly, and has excellent polymer compatibility (polymer attack is suppressed). Furthermore, it has high oil removal properties and excellent cleaning properties, and forms an azeotropic composition or azeotropic-like composition that behaves similarly to a single compound, making it suitable for cleaning resin products.

[0028] Furthermore, the azeotropic composition or azeotropic-like composition of the present invention can be suitably used as a refrigerant for cooling. In particular, because it exhibits azeotropic properties, it is also suitable as a refrigerant for use in a cooling method (boiling cooling) that includes a step of condensing the composition of the present invention and a step of evaporating it near the object to be cooled.

[0029] Furthermore, the azeotropic composition or azeotropic-like composition of the present invention can also be suitably used as a heat transfer medium.

[0030] Next, a method for efficiently removing chloroform contained in PFH by utilizing the formation of an azeotropic composition or azeotropic-like composition will be described. For example, chloroform may be introduced during the manufacturing process to obtain an azeotropic composition or azeotropic-like composition containing PFH. However, PFH is a useful solvent with high environmental performance, and from a cost perspective, there is a need to effectively recover PFH.

[0031] A PFH composition containing chloroform separates into two phases upon standing. However, a considerable amount of PFH is dissolved in the chloroform phase, and a considerable amount of chloroform is dissolved in the PFH phase. Therefore, simple phase separation cannot yield PFH with high purity (i.e., PFH with a small amount of dissolved chloroform). Furthermore, it is difficult to obtain high-purity PFH by simply distilling the separated two phases. Moreover, while it is possible to obtain PFH with a certain degree of purity by azeotropic distillation of the PFH phase obtained after separation, it still contains a considerable amount of chloroform.

[0032] As a result of investigating methods to obtain higher purity PFH from PFH containing chloroform, we discovered that by allowing PFH containing chloroform to stand at a low temperature to separate into two phases, recovering the PFH phase, and then distilling it, the azeotropic composition or azeotropic-like composition of chloroform and PFH flows out first, ultimately yielding a very high-purity PFH in the liquid phase, leading to the present invention. The present invention will be described in detail below with reference to examples.

[0033] <Compounds> The compounds used in the examples and comparative examples are as follows: ・PFH: Opteon® SF70 (boiling point 71.5°C), manufactured by Mitsui Chemours Fluoroproducts Co., Ltd. ・Chloroform (CHCl3): Reagent grade (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0034] The boiling point of the mixture consisting of PFH and chloroform was measured by the following method: [Boiling point (equilibrium reflux boiling point)] The boiling point (equilibrium reflux boiling point) was measured in accordance with JIS K 2233, except that the cooling water temperature was set to 5°C and the mixture was heated directly without anything placed between the hot plate and the flask.

[0035] [Example 1] The boiling points were measured using a Soxhlet extractor (B-811, manufactured by Nippon Buch Co., Ltd.) with varying compositions of PFH and chloroform, and the results are shown in Table 1 and Figure 1. Figure 3 is a schematic diagram of the Soxhlet extractor, and the boiling point measurement method is as follows. When the PFH content was 15 to 85% by weight, the boiling point was approximately 50°C, confirming the formation of an azeotropic composition or an azeotropic-like composition.

[0036] [Method for measuring boiling point: Measurement within the concentrated chloroform composition range] Place approximately 100 g of chloroform in a flask and heat until boiling. Inject any desired PFH from the top of the flask using a syringe. After confirming the temperature when the temperature of the liquid phase in the flask and the gas phase at the top of the extraction tube have stabilized, sample the liquid from the sampling lines of the flask and extraction tube. For any desired PFH, add an appropriate amount of PFH after sampling, within the range of chloroform:PFH = 100 to 50:0 to 50% by mass, and sample at each composition. The composition of each sampled liquid was analyzed each time using gas chromatography (Shimadzu Corporation, GC-2014A), and a boiling curve was created using the measured temperature and composition.

[0037] [Method for measuring boiling point: Measurement within the concentrated PFH composition range] Separately, approximately 100 g of PFH is placed in a flask and heated to a boil. An arbitrary amount of chloroform is injected from the top of the flask using a syringe. After confirming the temperature when the temperature of the liquid phase in the flask and the gas phase at the top of the extraction tube have stabilized, the liquid is sampled from the sampling lines of the flask and the extraction tube. For any chloroform, in the range of chloroform:PFH = 0 to 50:100 to 50% by mass, an appropriate amount of chloroform is added after the sample is taken, and samples are taken at each composition. The composition of each sampled liquid was analyzed each time using gas chromatography (Shimadzu Corporation, GC-2014A), and a boiling curve was created using the measured temperature and composition.

[0038]

[0039] [Example 2] A composition containing the same amount of PFH and chloroform (PFH: chloroform = 50% by mass: 50% by mass) was prepared, and its SP value was measured. The results are shown in Table 2. The SP value is a value measured as a solubility parameter. The closer the SP value is to the components of the stain, the higher the solubility. It can be seen that this composition has an SP value close to that of oils and fats and fluxes, and is excellent in stain removal ability. Also, a lower value of this indicates a lower polymer attack. The results of measuring the SP value are shown in Table 2 together with the GWP, boiling point, and the values of PHF and chloroform respectively.

[0040]

[0041] The SP value of the composition of chloroform: PFH = 50% by mass: 50% by mass is 6.2, which is not different from that of PFH, and it was found to have excellent compatibility with most polymers.

[0042] [Example 3] A composition of chloroform: PFH = 50% by mass: 50% by mass was prepared and left standing and stored overnight at 20°C, 2°C, -20°C, and -30°C, and it separated into two phases (chloroform phase and PFH phase). The ratio of PFH in the chloroform phase and the ratio of chloroform in the PFH phase were quantitatively analyzed for components under the following analysis conditions by gas chromatography. The summarized results are shown in Table 3. <Analysis conditions> Column: GC capillary column RTX-1, 105 m, manufactured by Restek Corporation Temperature: 60°C Split ratio: 20

[0043]

[0044] It was confirmed that by standing at low temperature, the separation of chloroform and PFH proceeded, and the amount of chloroform in the PFH phase decreased.

[0045] [Example 4] A composition of chloroform:PFH = 3 mass%:97 mass% was prepared and allowed to stand and stored at 20°C overnight, and it separated into two phases. After that, the lower-phase PFH phase (purity of PFH was 99.5 mass%) was recovered by an appropriate method, and distillation was performed at atmospheric pressure using a Soxhlet extraction apparatus (manufactured by Buchi Japan Co., Ltd., B-811), and component quantitative analysis was performed under the same analysis conditions as above using gas chromatography (manufactured by Shimadzu Corporation, GC-2014A). The results are shown in Table 4. Also, the distillation amount of PFH (mass%; horizontal axis) and the purity of PFH in the PFH phase (liquid phase) (mass%; vertical axis; □ indicates the purity in the liquid phase, and ○ indicates the purity in the gas phase) at that time are shown in Figure 2. The purity of PFH in the PFH phase (liquid phase) at the stage where 6.3 mass% of the PFH phase was distilled was 99.6 mass%, and at the stage where 11.9 mass% was distilled, it was 99.8 mass%, and it was confirmed that distillation could be performed while maintaining a high concentration thereafter.

[0046]

[0047] This is because the azeotropic temperature of the azeotropic composition is 50°C, the boiling point of chloroform is 62°C, and the boiling point of PFH is 71°C. First, by distillation, chloroform remaining in a small amount in the PFH phase forms an azeotropic composition or an azeotrope-like composition with PFH, and due to the difference in boiling points, the azeotropic (like) composition is distilled first, and then chloroform is distilled (however, since the chloroform remaining in the PFH phase is in a small amount, most of it forms an azeotropic composition or an azeotrope-like composition with PFH, so it is presumed that chloroform is hardly distilled alone). As a result, the PFH phase (liquid phase) is purified and a high-purity PFH phase is obtained.

Claims

1. An azeotropic composition or azeotropic-like composition comprising perfluoroheptene and chloroform.

2. The azeotropic composition or azeotropic-like composition according to claim 1, wherein the perfluoroheptene is 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoro-3-heptene and / or 1,1,1,2,3,4,4,5,5,6,6,7,7,7-tetradecafluoro-2-heptene.

3. The azeotropic composition or azeotropic-like composition according to claim 1 or 2, comprising 15 to 85% by mass of perfluoroheptene and 85 to 15% by mass of chloroform.

4. A method for removing chloroform from a composition containing perfluoroheptene and chloroform by azeotropic distillation, comprising: allowing the composition containing perfluoroheptene and chloroform to stand at a low temperature to separate it into two phases; recovering the perfluoroheptene phase; and distilling the perfluoroheptene phase.

5. The removal method according to claim 4, wherein the low temperature is -30 to 20°C.

Images