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

Abstract

An azeotrope-like composition containing vinylidene fluoride and tetrafluoroethylene, wherein the content of vinylidene fluoride is 60.0 mol% or more and less than 100 mol% relative to the total amount of the azeotrope-like composition, and the content of tetrafluoroethylene is more than 0 mol% and 40.0 mol% or less relative to the total amount of the azeotrope-like composition, and use thereof.

Description

Technical Field

[0001] This disclosure relates to azeotropic compositions, methods for manufacturing high-concentration vinylidene fluoride, containers containing azeotropic compositions, and methods for filling azeotropic compositions. Background Technology

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

[0003] For example, Patent Document 1 describes a method for manufacturing an olefin, 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 an alkaline earth metal with a haloalkane, wherein vinylidene fluoride is described as the olefin.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-107341 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In the manufacture of vinylidene fluoride, tetrafluoroethylene is sometimes mixed into the resulting vinylidene fluoride. Depending on the composition ratio of vinylidene fluoride to tetrafluoroethylene, it becomes a non-azeotropic composition. During transfer filling, when gas and liquid phases coexist, compositional changes occur.

[0009] One objective of this disclosure is to provide a novel azeotropic composition capable of suppressing compositional variations.

[0010] Another objective of this 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.

[0011] In other embodiments of this disclosure, the objective is to provide a container for holding an azeotropic composition filled with the aforementioned azeotropic composition.

[0012] Another objective of this disclosure is to provide a method for filling the aforementioned azeotropic composition.

[0013] Solution for solving the problem

[0014] This disclosure includes the following methods.

[0015] <1>

[0016] An azeotropic composition containing vinylidene fluoride and tetrafluoroethylene,

[0017] The content of vinylidene fluoride relative to the total amount of the azeotropic composition is 60.0 mol% or more and less than 100 mol%.

[0018] The content of tetrafluoroethylene is greater than 0 mol% and less than 40.0 mol% relative to the total amount of the azeotropic composition.

[0019] <2>

[0020] according to <1> The aforementioned azeotropic composition, wherein the content of vinylidene fluoride relative to the total amount of the azeotropic composition is 70.0 mol% or more and less than 100 mol%.

[0021] The content of tetrafluoroethylene is greater than 0 mol% and less than 30.0 mol% relative to the total amount of the azeotropic composition.

[0022] <3>

[0023] according to <1> The aforementioned azeotropic composition, wherein the content of vinylidene fluoride relative to the total amount of the azeotropic composition is 99.0 mol% or more and less than 100 mol%.

[0024] The content of tetrafluoroethylene relative to the total amount of the azeotropic composition is more than 0 mol% and less than 1.0 mol%.

[0025] <4>

[0026] according to <1> ~ <3> The azeotropic composition according to any one of the following methods, wherein the total content of vinylidene fluoride and tetrafluoroethylene is 90.0 mol% or more relative to the total amount of the azeotropic composition.

[0027] <5>

[0028] according to <1> ~ <4> The azeotropic composition described in any one of the above examples further comprises trifluoromethane.

[0029] <6>

[0030] according to <5> The azeotropic composition further comprises at least one element selected from the group consisting of methane, ethylene, hexafluoropropylene, and trifluoroethylene.

[0031] <7>

[0032] A method for producing high-concentration vinylidene fluoride includes: a step of distilling a distillation composition containing vinylidene fluoride and tetrafluoroethylene to obtain a first distillate.

[0033] In the first distillate, the content of vinylidene fluoride relative to the total content of vinylidene fluoride and tetrafluoroethylene is higher than the content of vinylidene fluoride relative to the total content of vinylidene fluoride and tetrafluoroethylene in the distillation composition.

[0034] In the first distillate, the content of vinylidene fluoride is greater than 60.0 mol% and less than 100 mol% relative to the total amount of the first distillate, and the content of tetrafluoroethylene is greater than 0 mol% and less than 40.0 mol% relative to the total amount of the first distillate.

[0035] <8>

[0036] A container for containing an azeotropic composition, wherein the composition is filled in a gas-liquid state in which gas and liquid phases coexist. <1> ~ <6> The azeotropic composition described in any one of the above.

[0037] <9>

[0038] A method for filling an azeotropic composition, which will... <1> ~ <6> The azeotropic composition described in any one of the above statements is from <8> The container containing the azeotropic composition is transferred and filled to the target supply container.

[0039] The effects of the invention

[0040] According to one embodiment of this disclosure, a novel azeotropic composition capable of suppressing compositional variations is provided.

[0041] According to another embodiment of this disclosure, a method for manufacturing high-concentration vinylidene fluoride is provided, which can efficiently obtain high-concentration vinylidene fluoride from a distillation composition containing vinylidene fluoride and tetrafluoroethylene.

[0042] According to another embodiment of the present disclosure, a container for containing an azeotropic composition is provided, which is filled with the above-described azeotropic composition.

[0043] According to another embodiment of this disclosure, a method for filling the above-described azeotropic composition is provided. Detailed Implementation

[0044] In this disclosure, the numerical range represented by "~" refers to the range in which the values ​​recorded before and after "~" are respectively the minimum and maximum values.

[0045] In the numerical ranges described in this disclosure, the upper or lower limit value recorded in a certain numerical range can be replaced by the upper or lower limit value of other numerical ranges described in different stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value recorded in a certain numerical range can also be replaced by the value shown in the embodiments.

[0046] In this disclosure, a combination of two or more preferred methods is a more preferred method.

[0047] In this disclosure, where there are multiple substances equivalent to each component, unless otherwise specified, the amount of each component refers to the total amount of the multiple substances.

[0048] [Azeotropic-like composition]

[0049] The azeotropic composition disclosed herein is an azeotropic composition containing vinylidene fluoride (hereinafter also referred to as "VdF") and tetrafluoroethylene (hereinafter also referred to as "TFE"). From the viewpoint of being able to make the relative volatility close to 1, the content of VdF relative to the total amount of the azeotropic composition is 60.0 mol% or more and less than 100 mol%, and the content of TFE relative to the total amount of the azeotropic composition is more than 0 mol% and less than 40.0 mol%.

[0050] The azeotropic composition exhibits no compositional change when repeatedly evaporated and condensed. Therefore, it has the advantage of minimal compositional variation during processes such as transfer filling where both gas and liquid phases coexist. It should be noted that the relative volatility of the azeotropic composition, as shown in the following formula, is 1.00.

[0051] Relative volatility = (molar percentage of VdF in the gas phase / molar percentage of TFE in the gas phase) / (molar percentage of VdF in the liquid phase / molar percentage of TFE in the liquid phase)

[0052] The composition of the azeotropic composition disclosed herein changes little during repeated evaporation and condensation.

[0053] In this disclosure, azeotropic-like compositions refer to compositions with a relative volatility in the range of 1.00 ± 0.05. The azeotropic-like compositions of this disclosure can be operated substantially equivalently to azeotropic compositions and have the advantage of minimal compositional variation when gas and liquid phases coexist during transfer filling.

[0054] In this disclosure, the azeotropic-like composition comprises an azeotropic composition.

[0055] Furthermore, in this disclosure, the azeotropic composition satisfies the aforementioned relative volatility at a pressure of 2.2 MPa.

[0056] The inventors have discovered that a composition containing VdF and TFE in a predetermined molar ratio forms an azeotropic-like composition. Previously, azeotropic-like compositions containing VdF and TFE were unknown. Because the composition containing VdF and TFE in a predetermined molar ratio forms an azeotropic-like composition, the composition changes little even when gas and liquid phases coexist, such as during transfer filling. Furthermore, when TFE is in excess in the composition containing VdF and TFE, the azeotropic-like composition can be separated by distillation. That is, by distillation, a composition with a high proportion of VdF can be obtained.

[0057] From the viewpoint of achieving a relative volatility closer to 1 and obtaining a copolymer with altered polymerization ratios of VdF and TFE, it is preferable that the VdF content relative to the total amount of the azeotropic composition is 70.0 mol% or more and less than 100 mol%, and the TFE content relative to the total amount of the azeotropic composition is more than 0 mol% and less than 30.0 mol%. More preferably, the VdF content relative to the total amount of the azeotropic composition is 80.0 mol% or more and less than 100 mol%, and the TFE content relative to the total amount of the azeotropic composition is more than 0 mol% and less than 20.0 mol%.

[0058] Furthermore, from the viewpoint of obtaining polyvinylidene fluoride (PVDF) with a relative volatility closer to 1, it is preferable that the VdF content relative to the total amount of the azeotropic composition is 99.0 mol% or more and less than 100 mol%, and the TFE content relative to the total amount of the azeotropic composition is more than 0 mol% and less than 1.0 mol%. Additionally, it is preferable that the VdF content relative to the total amount of the azeotropic composition is 99.0 to 99.9 mol%, and the TFE content relative to the total amount of the azeotropic composition is 0.1 to 1.0 mol%.

[0059] From the viewpoint of increasing the proportion of fluorine atoms in the polymer obtained using the azeotropic composition, the total content of VdF and TFE relative to the total amount of the azeotropic composition is preferably 90.0 mol% or more, more preferably 95.0 mol% or more, and even more preferably 99.0 mol% or more. The total content of VdF and TFE can be 100 mol%.

[0060] The azeotropic compositions disclosed herein may contain other components besides VdF and TFE.

[0061] Other components include byproducts of VdF production, such as trifluoromethane (R23), methane, ethylene, hexafluoropropylene, trifluoroethylene, and octafluorocyclobutane (C318).

[0062] The azeotropic composition disclosed herein may further include R23. R23 has a boiling point of -82.1°C, VdF has a boiling point of -84°C, and TFE has a boiling point of -76.5°C. Since the boiling point of R23 is close to that of VdF and TFE, compositional changes involving R23 are less likely to occur during transfer filling when both gas and liquid phases coexist.

[0063] The azeotropic compositions disclosed herein may further comprise at least one element selected from the group consisting of methane, ethylene, hexafluoropropylene, and trifluoroethylene. The azeotropic compositions disclosed herein may comprise all of methane, ethylene, hexafluoropropylene, and trifluoroethylene.

[0064] The VdF contained in the azeotropic composition disclosed herein is, for example, produced using 1,1,2,2-tetrafluorocyclobutane (C354). In the reaction process, the temperature inside the reactor is, for example, 600°C or higher. The contact time of C354 inside the reactor is, for example, 1 second or more. The pressure inside the reactor is, for example, 0.6 MPaG or less.

[0065] Although TFE is produced as a byproduct in the method for manufacturing VdF using C354, the azeotropic composition disclosed herein can be manufactured without removing the byproduct TFE. It should be noted that conventional VdF manufacturing methods other than those described above do not produce TFE as a byproduct; therefore, azeotropic compositions containing both VdF and TFE have not been previously studied.

[0066] The azeotropic composition disclosed herein can be manufactured by mixing VdF, which is produced by the method for producing VdF, with TFE.

[0067] The azeotropic compositions disclosed herein are useful as raw materials for polymers.

[0068] In one approach, the azeotropic composition disclosed herein can be polymerized to produce a fluorinated copolymer comprising structural units derived from VdF and structural units derived from TFE.

[0069] Alternatively, other polymerizable monomers can be added to the azeotropic composition disclosed herein to produce fluorinated copolymers.

[0070] Other polymerizable monomers can be either fluorinated or non-fluorinated.

[0071] That is, the fluorinated copolymers mentioned above may contain structural units derived from other polymerizable monomers besides those derived from VdF and TFE.

[0072] In addition, as another method, VdF can be extracted from the azeotropic composition disclosed herein and then polymerized to produce PVDF. It should be noted that PVDF can also be produced by directly carrying out the polymerization reaction without extracting VdF from the azeotropic composition disclosed herein.

[0073] Methods for manufacturing the aforementioned fluorinated copolymers and PVDF include, for example, suspension polymerization, emulsion polymerization, and solution polymerization using a polymerization initiator. Among these, suspension polymerization or emulsion polymerization is preferred from the perspective of ease of post-processing.

[0074] In polymerization, commonly known substances can be used as polymerization initiators, surfactants, chain transfer agents, and solvents. In suspension polymerization, fluorinated solvents can be used in addition to water.

[0075] There is no particular limitation on the polymerization temperature, for example, 0℃ to 100℃. The pressure in the polymerization reaction is usually 0 to 9.8 MPaG.

[0076] The weight-average molecular weight of the above-mentioned fluorinated copolymer and PVDF is preferably 50,000 to 2,000,000. More preferably, it is 80,000 to 1,700,000, and even more preferably, it is 100,000 to 150,000. The weight-average molecular weight is determined using gel permeation chromatography (GPC).

[0077] The aforementioned fluorinated copolymers and PVDF are useful as binders for secondary batteries, especially for lithium-ion secondary batteries.

[0078] Using at least one of the above-mentioned fluorinated copolymers and PVDF as a binder, an electrode binder can be prepared by mixing it with an electrode active material and an organic solvent.

[0079] The electrode mixture can be any type of positive electrode mixture or negative electrode mixture.

[0080] Examples of active electrode materials include positive electrode active materials and negative electrode active materials.

[0081] When the electrode mixture contains a positive electrode active material, it becomes a positive electrode mixture; when the electrode mixture contains a negative electrode active material, it becomes a negative electrode mixture.

[0082] Organic solvents include, for example, N-methyl-2-pyrrolidone, dimethylformamide, N,N-dimethylacetamide, N,N-dimethyl sulfoxide, hexamethylphosphoramide, 1,4-dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, and trimethyl phosphate.

[0083] In the manufacture of lithium-ion secondary batteries, the positive electrode active material can be any material capable of absorbing and releasing lithium ions. Known positive electrode active materials for lithium-ion secondary batteries can be used as positive electrode active materials. Examples of positive electrode active materials include lithium-containing transition metal oxides, lithium-containing transition metal composite oxides using one or more transition metals, transition metal oxides, transition metal sulfides, metal oxides, and olivine-type lithium metal salts.

[0084] In the manufacture of lithium-ion secondary batteries, known negative electrode active materials for lithium-ion secondary batteries can be used as the negative electrode active material. Examples of negative electrode active materials include at least one selected from the group consisting of lithium metal, lithium alloys, and carbon materials capable of absorbing and releasing lithium ions.

[0085] [Manufacturing method for high-concentration VdF]

[0086] The method for producing high-concentration VdF disclosed herein includes a step of distilling a distillation composition containing VdF and TFE to obtain a first distillate, wherein the VdF content in the first distillate is higher than the VdF content in the distillation composition relative to the total content of VdF and TFE, and wherein the VdF 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 TFE content is more than 0 mol% and less than 40.0 mol% relative to the total amount of the first distillate.

[0087] In this disclosure, "high concentration VdF" refers to VdF obtained by distillation with a concentration higher than that of VdF before distillation.

[0088] The distillation composition only needs to contain VdF and TFE, but may also contain other components besides VdF and TFE. Other components can include byproducts produced during the manufacture of VdF, specifically trifluoromethane (R23), methane, ethylene, hexafluoropropylene, trifluoroethylene, octafluorocyclobutane (C318), etc.

[0089] The total content of VdF and TFE relative to the total amount of the distillation composition is preferably 90.0 mol% or more, more preferably 95.0 mol% or more, and even more preferably 99.0 mol% or more. The total content of VdF and TFE may be 100 mol%.

[0090] The composition for distillation is preferably not an azeotropic composition, and more preferably a composition whose relative volatility is not in the range of 1.00 ± 0.05.

[0091] Specifically, the preferred content of VdF is less than 60.0 mol% relative to the total amount of the distillation composition, and the content of TFE is more than 40.0 mol% relative to the total amount of the distillation composition.

[0092] According to the method for producing high-concentration VdF according to this disclosure, a first distillate can be obtained, wherein the VdF content in the first distillate relative to the total content of VdF and TFE is higher than the VdF content in the distillation composition relative to the total content of VdF and TFE. In the first distillate, the VdF content relative to the total amount of the first distillate is 60.0 mol% or more and less than 100 mol%, and the TFE content relative to the total amount of the first distillate is more than 0 mol% and less than 40.0 mol%. That is, the first distillate is an azeotropic composition.

[0093] According to the method for producing high-concentration VdF disclosed herein, an azeotropic composition can be obtained.

[0094] There are no particular limitations on the distillation conditions, as long as a first distillate can be obtained, wherein the VdF content relative to the total content of VdF and TFE in the first distillate is higher than the VdF content relative to the total content of VdF and TFE in the distillation composition.

[0095] The distillation column can be a hollow distillation column or a multi-stage distillation column. Distillation can be batch or continuous. The preferred pressure conditions for distillation are atmospheric pressure (0.101325 MPa) to 3.0 MPa. As for temperature conditions, the preferred top temperature is -85℃ to 25℃.

[0096] When distilling using a multi-stage distillation column, the distillation composition is typically supplied from the middle section of the column, and the first distillate is obtained as a distillate from the top of the column.

[0097] Additionally, a second distillate is obtained as the bottom liquid from the column, wherein the VdF content in the second distillate, relative to the total content of VdF and TFE, is lower than the VdF content in the distillation composition relative to the total content of VdF and TFE.

[0098] The second distillate described above can be further distilled repeatedly as needed to obtain an azeotropic composition.

[0099] [Containers containing azeotropic compositions]

[0100] The container of the present disclosure containing the azeotropic composition is filled with the above-mentioned azeotropic composition in a gas-liquid state in which gas and liquid phases coexist.

[0101] There are no particular limitations on the method of filling the container with the azeotropic composition; generally known methods can be used. For example, all the components contained in the composition can be mixed and then the mixed azeotropic composition can be introduced into the container. Alternatively, each component contained in the azeotropic composition can be introduced into the container separately and mixed within the container. Alternatively, only a portion of the components contained in the azeotropic composition can be mixed, and the mixed component and the remaining component can be introduced into the container separately and mixed within the container.

[0102] There are no particular limitations on the container for a filled azeotropic composition, as long as it is capable of preserving the azeotropic composition in a gas-liquid state under internal pressure. Examples of containers include, for instance, storage tanks used as fixed storage containers, filled bottles used for transportation, and pressure-resistant containers such as refilled bottles.

[0103] There are no particular restrictions on the material of the container; examples include carbon steel, manganese steel, chromium-molybdenum steel, stainless steel, and aluminum alloy. Alternatively, the inner wall of the container can be lined with resin, glass, or other materials.

[0104] [Method for filling azeotropic compositions]

[0105] In the filling method of the azeotropic composition disclosed herein, the azeotropic composition is transferred from the container containing the azeotropic composition to the target supply container. According to the filling method of the azeotropic composition disclosed herein, the composition changes are minimal due to the transfer from the container containing the azeotropic composition to the target supply container.

[0106] There is no particular limitation on the type of container supplied to the target; any container similar to the one described above can be used.

[0107] Example

[0108] The present disclosure will be specifically described below through embodiments, but the present disclosure is not limited to these embodiments.

[0109] [Example 1]

[0110] VdF and TFE were placed in a 500 mL autoclave equipped with a pressure gauge. The pressure inside the autoclave reached 2.2 MPa and was maintained for a certain period to stabilize the composition. Samples were collected from the gas and liquid phases, and VdF and TFE were analyzed by gas chromatography to determine their composition ratio. The relative volatility was calculated from the composition ratio. The results are shown in Table 1. In Table 1, "%" refers to mole%.

[0111] Relative volatility = (molar percentage of VdF in the gas phase / molar percentage of TFE in the gas phase) / (molar percentage of VdF in the liquid phase / molar percentage of TFE in the liquid phase)

[0112] [Table 1]

[0113]

[0114] When the VdF / TFE ratio is 60.0 / 40.0~99.9 / 0.1, the relative volatility is in the range of 1.00±0.05. Furthermore, it can be seen that as the VdF content increases, the relative volatility approaches 1.

[0115] [Example 2]

[0116] The relative volatility was calculated using VdF, TFE, and R23 in the same manner as in Example 1. The results are shown in Table 2. In Table 2, "%" refers to moles.

[0117] [Table 2]

[0118]

[0119] When the VdF content is 60.000~99.900 mol%, the relative volatility is in the range of 1.00±0.05. Furthermore, it is known that as the VdF content increases, the relative volatility approaches 1.

[0120] As a distillation composition, a composition consisting of VdF and TFE, with VdF content of 40.0 mol% and TFE content of 60.0 mol%, was prepared. This distillation composition was fed into a distillation column with a height of 2 m and an inner diameter of 4.5 cm at a rate of 300 g / hr, and distillation was carried out continuously at an operating pressure of 2.2 MPa and a column top temperature of 7.8 °C. The first distillate was extracted from the top of the column, and the second distillate was extracted from the bottom. The composition of the extracted first and second distillates was analyzed by gas chromatography. The results are shown in Table 3. In Table 3, "%" refers to mol%.

[0121] [Table 3]

[0122]

[0123] As shown in Table 3, a first distillate was obtained by distillation. In the first distillate, 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. The first distillate is an azeotropic composition.

[0124] The entire contents of Japanese Patent Application No. 2023-203193, filed on November 30, 2023, are incorporated herein by reference. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as those specifically and separately described herein.

Claims

1. An azeotropic composition comprising vinylidene fluoride and tetrafluoroethylene, The content of the vinylidene fluoride relative to the total amount of the azeotropic composition is 60.0 mol% or more and less than 100 mol%. The content of the tetrafluoroethylene relative to the total amount of the azeotropic composition is more than 0 mol% and less than 40.0 mol%.

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

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

4. The azeotropic composition according to any one of claims 1 to 3, wherein, The combined content of the vinylidene fluoride and the tetrafluoroethylene is 90.0 mol% or more relative to the total amount of the azeotropic composition.

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

6. The azeotropic composition according to claim 5, further comprising at least one selected from the group consisting of methane, ethylene, hexafluoropropylene, and trifluoroethylene.

7. A method for manufacturing high-concentration vinylidene fluoride, comprising: The process of distilling a distillation composition containing vinylidene fluoride and tetrafluoroethylene to obtain the first distillate. In the first distillate, the content of vinylidene fluoride relative to the total content of vinylidene fluoride and tetrafluoroethylene is higher than the content of vinylidene fluoride relative to the total content of vinylidene fluoride and tetrafluoroethylene in the distillation composition. In the first distillate, the content of vinylidene fluoride relative to the total amount of the first distillate is more than 60.0 mol% and less than 100 mol%, and the content of tetrafluoroethylene relative to the total amount of the first distillate is more than 0 mol% and less than 40.0 mol%.

8. A container for containing an azeotropic composition, wherein, An azeotropic composition according to any one of claims 1 to 3 is filled in a gas-liquid state in which gas and liquid phases coexist.

9. A method for filling an azeotropic composition, wherein the azeotropic composition of any one of claims 1 to 3 is transferred from the container containing the azeotropic composition of claim 8 to a target supply container.

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