Azeotrope-like composition, method for producing high-concentration vinylidene fluoride, container containing azeotrope-like composition, and method for filling azeotrope-like composition

Abstract

Provided are: an azeotrope-like composition containing vinylidene fluoride and tetrafluoroethylene, wherein the vinylidene fluoride content is 60.0 mol% to less than 100 mol% with respect to the total amount of the azeotrope-like composition, and the tetrafluoroethylene content is more than 0 mol% to 40.0 mol% with respect to the total amount of the azeotrope-like composition; and a use therefor.

Description

Azeotrope-like composition, method for producing high-concentration vinylidene fluoride, container containing azeotrope-like composition, and method for filling azeotrope-like composition

[0001] The present disclosure relates to an azeotrope-like composition, a method for producing a high concentration vinylidene fluoride, a container containing an azeotrope-like composition, and a method for filling an azeotrope-like composition.

[0002] Vinylidene fluoride is useful as a monomer for fluororesins.

[0003] For example, Patent Document 1 describes a method for producing an alkene, which includes a step of contacting a solution containing an alcohol having three or more carbon atoms and a hydroxide of an alkali metal and / or alkaline earth metal with a halogenated alkane, and describes vinylidene fluoride as the alkene.

[0004] Japanese Patent Application Laid-Open No. 2021-107341

[0005] In the production of vinylidene fluoride, tetrafluoroethylene may be mixed into the resulting vinylidene fluoride. Depending on the composition ratio of vinylidene fluoride and tetrafluoroethylene, a non-azeotropic composition may result, and composition fluctuations may occur when a gas phase and a liquid phase coexist during transfer and filling, for example.

[0006] An object of one embodiment of the present disclosure is to provide a new azeotrope-like composition that can suppress composition fluctuations.An object of another embodiment of the present disclosure is to provide a method for producing high-concentration vinylidene fluoride that can efficiently obtain high-concentration vinylidene fluoride from a distillation composition containing vinylidene fluoride and tetrafluoroethylene.An object of another embodiment of the present disclosure is to provide a container containing the azeotrope-like composition that is filled with the azeotrope-like composition.An object of another embodiment of the present disclosure is to provide a method for filling the azeotrope-like composition.

[0007] The present disclosure includes the following aspects: <1> An azeotrope-like composition containing vinylidene fluoride and tetrafluoroethylene, wherein the vinylidene fluoride content is 60.0 mol% or more and less than 100 mol%, based on the total amount of the azeotrope-like composition, and the tetrafluoroethylene content is more than 0 mol% and not more than 40.0 mol%, based on the total amount of the azeotrope-like composition. <2> The azeotrope-like composition according to <1>, wherein the vinylidene fluoride content is 70.0 mol% or more and less than 100 mol%, based on the total amount of the azeotrope-like composition, and the tetrafluoroethylene content is more than 0 mol% and not more than 30.0 mol%, based on the total amount of the azeotrope-like composition. <3> The azeotrope-like composition according to <1>, wherein the vinylidene fluoride content is 99.0 mol% or more and less than 100 mol%, based on the total amount of the azeotrope-like composition, and the tetrafluoroethylene content is more than 0 mol% and not more than 1.0 mol%, based on the total amount of the azeotrope-like composition. <4> The azeotrope-like composition according to any one of <1> to <3>, wherein the total content of vinylidene fluoride and tetrafluoroethylene is 90.0 mol % or more based on the total amount of the azeotrope-like composition. <5> The azeotrope-like composition according to any one of <1> to <4>, further comprising trifluoromethane. <6> The azeotrope-like composition according to <5>, further comprising at least one member selected from the group consisting of methane, ethylene, hexafluoropropene, and trifluoroethylene. <7> A method for producing high-concentration vinylidene fluoride, comprising the step of distilling a composition for distillation containing vinylidene fluoride and tetrafluoroethylene to obtain a first distillate having a vinylidene fluoride content relative to the total content of vinylidene fluoride and tetrafluoroethylene that is higher than the vinylidene fluoride content relative to the total content of vinylidene fluoride and tetrafluoroethylene in the composition for distillation, wherein the vinylidene fluoride content in the first distillate is 60.0 mol % or more and less than 100 mol %, relative to the total amount of the first distillate, and the tetrafluoroethylene content is more than 0 mol % and 40.0 mol % or less, relative to the total amount of the first distillate. <8> A container containing an azeotrope-like composition according to any one of <1> to <6>, filled with the azeotrope-like composition in a gas-liquid state in which a gas phase and a liquid phase coexist.<9> A method for filling an azeotrope-like composition, comprising transferring and filling the azeotrope-like composition according to any one of <1> to <6> from a container containing the azeotrope-like composition according to <8> to a destination container.

[0008] According to one embodiment of the present disclosure, a new azeotrope-like composition capable of suppressing composition fluctuations is provided. According to another embodiment of the present disclosure, a method for producing high-concentration vinylidene fluoride capable of efficiently obtaining high-concentration vinylidene fluoride from a distillation composition containing vinylidene fluoride and tetrafluoroethylene is provided. According to another embodiment of the present disclosure, a container containing the azeotrope-like composition is provided, the container being filled with the azeotrope-like composition. According to another embodiment of the present disclosure, a method for filling the azeotrope-like composition is provided.

[0009] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, when there are multiple substances corresponding to each component, the amount of each component means the total amount of multiple substances, unless otherwise specified.

[0010] [Azeotrope-Like Composition] The azeotrope-like composition of the present disclosure is an azeotrope-like composition containing vinylidene fluoride (hereinafter also referred to as "VdF") and tetrafluoroethylene (hereinafter also referred to as "TFE"), and from the viewpoint of enabling the relative volatility to approach 1, the VdF content is 60.0 mol % or more and less than 100 mol %, based on the total amount of the azeotrope-like composition, and the TFE content is more than 0 mol % and 40.0 mol % or less, based on the total amount of the azeotrope-like composition.

[0011] The azeotropic composition does not undergo any change in composition when repeatedly evaporated and condensed.Therefore, when transferring and filling, etc., when gas phase and liquid phase coexist, there is an advantage that there is little compositional change.The azeotropic composition has a relative volatility of 1.00, as shown in the following formula: relative volatility = (mol% of VdF in the gas phase / mol% of TFE in the gas phase) / (mol% of VdF in the liquid phase / mol% of TFE in the liquid phase)

[0012] The azeotrope-like composition of the present disclosure exhibits little compositional fluctuation when subjected to repeated evaporation and condensation. In this disclosure, an azeotrope-like composition refers to a composition having a relative volatility in the range of 1.00±0.05. The azeotrope-like composition of the present disclosure can be handled in a manner similar to an azeotropic composition, and has the advantage of little compositional fluctuation when a gas phase and a liquid phase coexist, such as during transfer and filling. In this disclosure, the azeotrope-like composition includes an azeotropic composition. Furthermore, in this disclosure, the azeotrope-like composition satisfies the above relative volatility at a pressure of 2.2 MPa.

[0013] The present inventors have found that a composition containing VdF and TFE in a predetermined molar ratio forms an azeotrope-like composition. Conventionally, no azeotrope-like composition containing VdF and TFE has been known. Since a composition containing VdF and TFE in a predetermined molar ratio forms an azeotrope-like composition, there is little compositional fluctuation when a gas phase and a liquid phase coexist, such as during transfer and filling. Furthermore, when TFE is in excess in a composition containing VdF and TFE, the azeotrope-like composition can be separated by distillation. That is, a composition with a high VdF content can be obtained by distillation.

[0014] From the viewpoint of bringing the relative volatility closer to 1 and obtaining a copolymer having a varied polymerization ratio of VdF and TFE, the VdF content is preferably 70.0 mol% or more and less than 100 mol% relative to the total amount of the azeotrope-like composition, and the TFE content is preferably more than 0 mol% and less than 30.0 mol% relative to the total amount of the azeotrope-like composition. Furthermore, the VdF content is more preferably 80.0 mol% or more and less than 100 mol% relative to the total amount of the azeotrope-like composition, and the TFE content is more than 0 mol% and less than 20.0 mol% relative to the total amount of the azeotrope-like composition.

[0015] From the viewpoint of bringing the relative volatility closer to 1 and obtaining polyvinylidene fluoride (PVDF), it is preferable that the VdF content be 99.0 mol % or more and less than 100 mol % based on the total amount of the azeotrope-like composition, and that the TFE content be more than 0 mol % and 1.0 mol % or less based on the total amount of the azeotrope-like composition. It is also preferable that the VdF content be 99.0 to 99.9 mol % based on the total amount of the azeotrope-like composition, and that the TFE content be 0.1 to 1.0 mol % based on the total amount of the azeotrope-like composition.

[0016] From the viewpoint of increasing the proportion of fluorine atoms in the polymer obtained using the azeotrope-like composition, the total content of VdF and TFE is preferably 90.0 mol% or more, more preferably 95.0 mol% or more, and even more preferably 99.0 mol% or more, based on the total amount of the azeotrope-like composition. The total content of VdF and TFE may be 100 mol%.

[0017] The azeotrope-like composition of the present disclosure may contain components other than VdF and TFE. Examples of other components include by-products produced during the production of VdF, such as trifluoromethane (R23), methane, ethylene, hexafluoropropene, trifluoroethylene, and octafluorocyclobutane (C318).

[0018] The azeotrope-like composition of the present disclosure may further contain R23. The boiling point of R23 is −82.1° C., the boiling point of VdF is −84° C., and the boiling point of TFE is −76.5° C. Since the boiling point of R23 is close to the boiling points of VdF and TFE, composition fluctuations including R23 are unlikely to occur when a gas phase and a liquid phase coexist, for example, during transfer and filling.

[0019] The azeotrope-like compositions of the present disclosure may further comprise at least one selected from the group consisting of methane, ethylene, hexafluoropropene, and trifluoroethylene. The azeotrope-like compositions of the present disclosure may comprise all of methane, ethylene, hexafluoropropene, and trifluoroethylene.

[0020] The VdF contained in the azeotrope-like composition of the present disclosure is produced, for example, using 1,1,2,2-tetrafluorocyclobutane (C354). In the reaction step, the temperature in the reactor is, for example, 600°C or higher. The contact time of C354 in the reactor is, for example, 1 second or longer. The pressure in the reactor is, for example, 0.6 MPaG or lower. In the method of producing VdF using C354, TFE is by-produced, but the azeotrope-like composition of the present disclosure can be produced without removing the by-produced TFE. Note that, since TFE is not by-produced in general VdF production methods other than the above production method, obtaining an azeotrope-like composition containing VdF and TFE has not been considered in the past.

[0021] The azeotrope-like compositions of the present disclosure may be produced by mixing VdF produced by a method for producing VdF with TFE.

[0022] The azeotrope-like composition of the present disclosure is useful as a raw material for polymers. In one embodiment, the azeotrope-like composition of the present disclosure can be polymerized to produce a fluorine-containing copolymer containing a structural unit derived from VdF and a structural unit derived from TFE. Furthermore, other polymerizable monomers may be further added to the azeotrope-like composition of the present disclosure to produce a fluorine-containing copolymer. The other polymerizable monomers may be fluorine-containing or non-fluorine-containing monomers.

[0023] That is, the above-mentioned fluorine-containing copolymer may contain a constituent unit derived from a polymerizable monomer other than the constituent unit derived from VdF and the constituent unit derived from TFE.

[0024] In another embodiment, PVDF may be produced by extracting VdF from the azeotrope-like composition of the present disclosure and then polymerizing the VdF. Alternatively, PVDF may be produced by directly polymerizing the azeotrope-like composition of the present disclosure without extracting VdF.

[0025] Examples of methods for producing the fluorine-containing copolymer and PVDF include methods of carrying out suspension polymerization, emulsion polymerization, solution polymerization, etc. using a polymerization initiator. Among these, suspension polymerization or emulsion polymerization is preferred from the standpoint of ease of post-treatment, etc. In the polymerization, commonly known polymerization initiators, surfactants, chain transfer agents, and solvents can be used. In the suspension polymerization, a fluorine-based solvent may be used in addition to water.

[0026] The polymerization temperature is not particularly limited and is, for example, 0 to 100° C. The pressure in the polymerization reaction is usually 0 to 9.8 MPaG.

[0027] The weight average molecular weight of the fluorine-containing copolymer and PVDF is preferably from 50,000 to 2,000,000, more preferably from 80,000 to 1,700,000, and even more preferably from 100,000 to 150,000. The weight average molecular weight is measured using gel permeation chromatography (GPC).

[0028] The above-mentioned fluorine-containing copolymer and PVDF are useful as binders for secondary batteries, and are particularly useful as binders for lithium ion secondary batteries.

[0029] At least one of the above-mentioned fluorine-containing copolymer and PVDF is used as a binder, and mixed with an electrode active material and an organic solvent to prepare an electrode mixture.

[0030] The electrode mixture may be either a positive electrode mixture or a negative electrode mixture.

[0031] Examples of the electrode active material include a positive electrode active material and a negative electrode active material. When the electrode mixture contains a positive electrode active material, it becomes a positive electrode mixture, and when the electrode mixture contains a negative electrode active material, it becomes a negative electrode mixture.

[0032] Examples of organic solvents include N-methyl-2-pyrrolidone, dimethylformamide, N,N-dimethylacetamide, N,N-dimethylsulfoxide, hexamethylphosphoamide, 1,4-dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, and trimethyl phosphate.

[0033] When manufacturing a lithium ion secondary battery, the positive electrode active material may be any material capable of absorbing and releasing lithium ions. Known positive electrode active materials for lithium ion secondary batteries can be used as the positive electrode active material. Examples of the positive electrode active material include lithium-containing transition metal oxides, lithium-containing transition metal composite oxides containing one or more transition metals, transition metal oxides, transition metal sulfides, metal oxides, and olivine-type metal lithium salts.

[0034] When manufacturing a lithium ion secondary battery, a known negative electrode active material for lithium ion secondary batteries can be used as the negative electrode active material, for example, at least one selected from the group consisting of lithium metal, lithium alloys, and carbon materials capable of absorbing and releasing lithium ions.

[0035] [Method for producing high-concentration VdF] The method for producing high-concentration VdF of the present disclosure includes a step of distilling a distillation composition containing VdF and TFE to obtain a first distillate in which the content of VdF relative to the total content of VdF and TFE is higher than the content of VdF relative to the total content of VdF and TFE in the distillation composition, and the VdF content in the first distillate is 60.0 mol% or more and less than 100 mol%, based on the total amount of the first distillate, and the TFE content is more than 0 mol% and 40.0 mol% or less, based on the total amount of the first distillate.

[0036] In the present disclosure, "high-concentration VdF" refers to VdF obtained by distillation, which has a higher concentration than the concentration of VdF before distillation.

[0037] The distillation composition may contain VdF and TFE, and may also contain other components besides VdF and TFE. Examples of other components include by-products produced during the production of VdF, such as trifluoromethane (R23), methane, ethylene, hexafluoropropene, trifluoroethylene, and octafluorocyclobutane (C318).

[0038] The total content of VdF and TFE is preferably 90.0 mol% or more, more preferably 95.0 mol% or more, and even more preferably 99.0 mol% or more, based on the total amount of the distillation composition. The total content of VdF and TFE may be 100 mol%.

[0039] The distillation composition is preferably not an azeotrope-like composition, and is preferably a composition having a relative volatility not in the range of 1.00±0.05. Specifically, the VdF content is preferably less than 60.0 mol% based on the total amount of the distillation composition, and the TFE content is preferably more than 40.0 mol% based on the total amount of the distillation composition.

[0040] According to the method for producing high-concentration VdF of the present disclosure, a first distillate can be obtained in which the VdF content relative to the total content of VdF and TFE is higher than the VdF content relative to the total content of VdF and TFE in the distillation composition. In the first distillate, the VdF content is 60.0 mol% or more and less than 100 mol% relative to the total amount of the first distillate, and the TFE content is more than 0 mol% and less than 40.0 mol% relative to the total amount of the first distillate. That is, the first distillate is an azeotrope-like composition. According to the method for producing high-concentration VdF of the present disclosure, an azeotrope-like composition can be obtained.

[0041] The distillation conditions are not particularly limited as long as a first distillate can be obtained in which the VdF content relative to the total content of VdF and TFE is higher than the VdF content relative to the total content of VdF and TFE in the composition for distillation. The distillation column may be a hollow distillation column or a multi-stage distillation column. The distillation may be a batch type or a continuous type. The pressure condition for the distillation is preferably atmospheric pressure (0.101325 MPa) to 3.0 MPa. As for the temperature condition, the column top temperature is preferably −85 to 25° C.

[0042] When distillation is carried out using a multi-stage distillation column, the distillation composition is usually fed to the middle stage of the distillation column, and a first distillate is obtained as a distillate from the top of the distillation column. A second distillate, in which the VdF content relative to the total content of VdF and TFE in the distillation composition is lower than the VdF content relative to the total content of VdF and TFE in the distillation composition, is obtained as a bottoms product from the column. The second distillate can be further subjected to repeated distillation as necessary to obtain an azeotrope-like composition.

[0043] [Container Filled with Azeotrope-Like Composition] The container filled with the azeotrope-like composition of the present disclosure is filled with the azeotrope-like composition in a gas-liquid state in which a gas phase and a liquid phase coexist.

[0044] The method for filling the azeotrope-like composition into a container is not particularly limited, and any commonly known method can be used. For example, all components contained in the composition may be mixed, and then the mixed azeotrope-like composition may be introduced into a container. Alternatively, each component contained in the azeotrope-like composition may be introduced individually into a container and mixed within the container. Alternatively, only some of the components contained in the azeotrope-like composition may be mixed, and the mixed component and the remaining components may be introduced individually into a container and mixed within the container.

[0045] The container into which the azeotrope-like composition is filled is not particularly limited as long as it is a container that can store the azeotrope-like composition in a gas-liquid state under internal pressure. Examples of the container include pressure-resistant containers such as storage tanks that are fixed storage containers, filling cylinders used for transportation, and secondary filling cylinders.

[0046] The material of the container is not particularly limited, and examples thereof include carbon steel, manganese steel, chromium-molybdenum steel, stainless steel, and aluminum alloy. The inner wall of the container may be lined with resin, glass, or the like.

[0047] [Method for Filling Azeotrope-Like Composition] The method for filling an azeotrope-like composition of the present disclosure involves transferring and filling the azeotrope-like composition from a container containing the azeotrope-like composition to a destination container. According to the method for filling an azeotrope-like composition of the present disclosure, there is little variation in composition when the azeotrope-like composition is transferred from the container containing the azeotrope-like composition to the destination container.

[0048] The type of the supply destination container is not particularly limited, and examples include the same containers as those described above.

[0049] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to these examples.

[0050] [Example 1] VdF and TFE were placed in a 500 mL autoclave equipped with a pressure gauge, and after the pressure inside the autoclave reached 2.2 MPa, the pressure was maintained for a certain period of time to stabilize the composition inside the autoclave. Samples were taken from the gas phase and liquid phase, and VdF and TFE were analyzed by gas chromatography to measure the composition ratio between the two. The relative volatility was calculated from the composition ratio between the two. The results are shown in Table 1. In Table 1, "%" means mol %. Relative volatility = (mol % of VdF in the gas phase / mol % of TFE in the gas phase) / (mol % of VdF in the liquid phase / mol % of TFE in the liquid phase).

[0051]

[0052] It was found that when the VdF / TFE ratio was 60.0 / 40.0 to 99.9 / 0.1, the relative volatility was in the range of 1.00±0.05. It was also found that the higher the VdF content, the closer the relative volatility became to 1.

[0053] [Example 2] Using VdF, TFE, and R23, the relative volatility was calculated in the same manner as in Example 1. The results are shown in Table 2. In Table 2, "%" means mol%.

[0054]

[0055] It was found that when the VdF content was 60.000 to 99.900 mol %, the relative volatility was in the range of 1.00±0.05. It was also found that as the VdF content increased, the relative volatility approached 1.

[0056] A distillation composition was prepared, consisting of VdF and TFE, with a VdF content of 40.0 mol% and a TFE content of 60.0 mol%. This distillation composition was fed at a rate of 300 g / hr to a distillation column having a height of 2 m and an inner diameter of 4.5 cm, and distillation was carried out continuously at an operating pressure of 2.2 MPa and a column top temperature of 7.8°C. A first distillate was extracted from the top of the column, and a second distillate was extracted from the bottom of the column. The compositions of the extracted first distillate and second distillate were analyzed by gas chromatography. The results are shown in Table 3. In Table 3, "%" means mol%.

[0057]

[0058] From Table 3, it was found that the distillation yielded a first distillate in which the content of VdF relative to the total content of VdF and TFE was higher than the content of VdF relative to the total content of VdF and TFE in the composition for distillation, and that the first distillate was an azeotrope-like composition.

[0059] The disclosure of Japanese Patent Application No. 2023-203193, filed on November 30, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. An azeotrope-like composition containing vinylidene fluoride and tetrafluoroethylene, wherein the vinylidene fluoride content is 60.0 mol% or more and less than 100 mol% based on the total amount of the azeotrope-like composition, and the tetrafluoroethylene content is more than 0 mol% and not more than 40.0 mol% based on the total amount of the azeotrope-like composition.

2. The azeotrope-like composition according to claim 1, wherein the vinylidene fluoride content is 70.0 mol% or more and less than 100 mol% based on the total amount of the azeotrope-like composition, and the tetrafluoroethylene content is more than 0 mol% and 30.0 mol% or less based on the total amount of the azeotrope-like composition.

3. The azeotrope-like composition according to claim 1, wherein the vinylidene fluoride content is 99.0 mol% or more and less than 100 mol% based on the total amount of the azeotrope-like composition, and the tetrafluoroethylene content is more than 0 mol% and 1.0 mol% or less based on the total amount of the azeotrope-like composition.

4. An azeotrope-like composition according to any one of claims 1 to 3, wherein the combined content of said vinylidene fluoride and said tetrafluoroethylene is 90.0 mol % or more based on the total amount of said azeotrope-like composition.

5. The azeotrope-like composition according to any one of claims 1 to 3, further comprising trifluoromethane.

6. The azeotrope-like composition of claim 5, further comprising at least one member selected from the group consisting of methane, ethylene, hexafluoropropene, and trifluoroethylene.

7. A method for producing high concentration vinylidene fluoride, comprising the step of distilling a distillation composition containing vinylidene fluoride and tetrafluoroethylene to obtain a first distillate in which the content of vinylidene fluoride relative to the total content of vinylidene fluoride and tetrafluoroethylene in the distillation composition is higher than the content of vinylidene fluoride relative to the total content of vinylidene fluoride and tetrafluoroethylene in the distillation composition, wherein the content of vinylidene fluoride in the first distillate is 60.0 mol% or more and less than 100 mol%, relative to the total amount of the first distillate, and the content of tetrafluoroethylene is more than 0 mol% and 40.0 mol% or less, relative to the total amount of the first distillate.

8. A container containing an azeotrope-like composition according to any one of claims 1 to 3, which is filled in a gas-liquid state in which a gas phase and a liquid phase coexist.

9. A method for filling an azeotrope-like composition, comprising transferring and filling the azeotrope-like composition according to any one of claims 1 to 3 from a container containing the azeotrope-like composition according to claim 8 into a destination container.