Method for dissolving and precipitating polymer compound, method for recovering good solvent phase and poor solvent phase, and method for purifying polymer compound

Abstract

Provided are: a method for dissolving and precipitating a polymer compound; a method for recovering a good solvent phase and a poor solvent phase using the method for dissolving and precipitating a polymer compound; and a method for purifying a polymer compound. The method for dissolving and precipitating a polymer compound includes: a step for separating a phase 1 and a phase 2 in a phase-separated state by setting a mixed solvent, which is composed of a component A, a component B that is immiscible with the component A, and a component C that is miscible with both the component A and the component B, and which exhibits a temperature-dependent phase change behavior, to a temperature that is lower than the phase change temperature; a step for obtaining a solution that contains a polymer compound by dissolving the polymer compound in either the phase 1 or the phase 2, which is a good solvent of the polymer compound; and a step for precipitating the polymer compound by adding either the phase 1 or the phase 2, which is a poor solvent of the polymer compound, to the solution and setting the resultant material to a temperature that exceeds the phase change temperature.

Description

Method for Dissolving and Precipitating Polymer Compound, Method for Recovering Good Solvent Phase and Poor Solvent Phase, and Method for Purifying Polymer Compound

[0001] The present disclosure relates to a method for dissolving and precipitating a polymer compound, a method for recovering a good solvent phase and a poor solvent phase, and a method for purifying a polymer compound.

[0002] In recent years, due to the reduction of environmental impact and the like, the reuse of components has been demanded, and various techniques for separating components have been studied.

[0003] For example, Patent Document 1 discloses "for a one-phase mixed component αβ containing component A and component B, adding component C, and at a temperature T1 of the mixed component αβγ containing component A, component B, and component C, a first separation unit that separates a separation component αγ mainly containing component A and component C and a separation component β mainly containing component B, and changing the temperature of the separation component αγ to temperature T2, and a second separation unit that separates a separation component α mainly containing component A and a separation component γ mainly containing component C, and the component C shows a miscible behavior with respect to component A at the temperature T1 of the mixed component αβγ, shows a separation behavior with respect to component B at the temperature T1 of the mixed component αβγ, and shows a separation behavior with respect to component A at the temperature T2 of the separation component αγ, a component separation system."

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2024 - 110910

[0005] Patent Document 1 describes a method for dissolving and precipitating polymers using a xylene-ethylene carbonate system, which is a solvent system exhibiting UCST (Upper Critical Solution Temperature) type phase change behavior. This method eliminates the need for solvent separation by distillation, which consumes a lot of energy, after dissolution and precipitation of the polymer, and allows for solvent reuse through a simple liquid-liquid separation operation. On the other hand, the only polymer compounds to which this technology can be applied are polyolefins, where the xylene phase, a nonpolar solvent, acts as a good solvent and the ethylene carbonate phase, an aprotic polar solvent, acts as a poor solvent. It is difficult to apply this technology to polymer compounds that require a combination of a protic solvent and a nonpolar solvent for the good and poor solvent roles. Furthermore, this technology requires the use of ethylene carbonate, but ethylene carbonate has a melting point of 34°C to 37°C, and it is necessary to maintain a temperature above its melting point to prevent clogging of the processing container.

[0006] Therefore, the object of this disclosure is to provide a method for dissolving and precipitating polymer compounds that can perform dissolution and precipitation treatment on various polymer compounds. Another object of this disclosure is to provide a method for recovering a good solvent phase and a poor solvent phase using the above-mentioned method for dissolving and precipitating polymer compounds, as well as a method for purifying polymer compounds.

[0007] Means for solving the above problems include the following embodiments: <1> A method for dissolving and precipitating a polymer compound, comprising the steps of: separating phase 1 and phase 2 in a phase-separated state by heating a mixed solvent consisting of component A, component B which is immiscible with respect to component A, and component C which is miscible with respect to both component A and component B, and exhibiting temperature-dependent phase change behavior, to a temperature below the phase change temperature; dissolving a polymer compound in either phase 1 or phase 2 which is a good solvent for the polymer compound to obtain a solution containing the polymer compound; and adding either phase 1 or phase 2 which is a poor solvent for the polymer compound to the solution, and precipitating the polymer compound by heating to a temperature above the phase change temperature. <2> The method for dissolving and precipitating a polymer compound according to <1>, wherein component A is an aromatic hydrocarbon and component B is a molecule having two or more OH groups in its molecule. <3> The method for dissolving and precipitating a polymer compound according to <1>, wherein component C is at least one selected from the group consisting of monohydric alcohols having 3 or less carbon atoms, ketones, cyclic carbonates having 2 or more carbon atoms without an acyclic alkyl group, and cyclic ethers having 2 or more carbon atoms without an acyclic alkyl group. <4> The method for dissolving and precipitating a polymer compound according to <1>, wherein the temperature-dependent phase change behavior exhibits an upper limit critical eutectic temperature, and the critical temperature at 1 atmosphere is in the range of 10°C to 140°C. <5> The method for dissolving and precipitating a polymer compound according to <1>, wherein component A contains xylene, component B contains at least one selected from the group consisting of water, ethylene glycol, and 1,2-propanediol, and component C contains at least one selected from the group consisting of methanol, ethanol, 2-propanol, acetone, propylene carbonate, and 1,4-dioxane. <6> The method for dissolving and precipitating a polymer compound according to <1>, wherein the polymer compound is a polyolefin, a polyacrylate, or a polyamide. <7> The method for dissolving and precipitating a polymer compound according to <1>, wherein the mass ratio of component B to component A is 0.1 or more and 2.0 or less. <8> The method for dissolving and precipitating a polymer compound according to <1>, wherein the mass ratio of component C to component A is 0.1 or more and 2.0 or less.<9> A method for recovering a good solvent phase and a poor solvent phase, comprising the steps of separating the polymer compound from the solvent after the precipitation step in the dissolution-precipitation method of a polymer compound according to any one of <1> to <8>, and cooling the solvent to below the phase change temperature to separate the liquid and recover the good solvent phase and the poor solvent phase, respectively. <10> A method for purifying a polymer compound, comprising the steps of separating the polymer compound from the solvent after the precipitation step in the dissolution-precipitation method of a polymer compound according to any one of <1> to <8>, dissolving the separated polymer compound in a solvent other than the solvent and removing the liberated impurities, and precipitating the polymer compound from the dissolved solution from which the impurities have been removed.

[0008] This disclosure provides a method for dissolving and precipitating polymer compounds that can perform dissolution and precipitation treatments on various polymer compounds. Furthermore, this disclosure provides a method for recovering a good solvent phase and a poor solvent phase using the above polymer compound dissolution and precipitation method, as well as a method for purifying polymer compounds.

[0009] This figure shows the phase change behavior of the UCST type. This figure shows the relationship between the miscibility behavior of each component A to C. This is an example diagram showing the relationship between the composition and miscibility of components A, B and C. This is a block diagram showing an example of a dissolution-precipitation method for polymer compounds according to this disclosure. This is a block diagram showing an example of a purification method for polymer compounds according to this disclosure. This figure shows the heating weight change of each recovered product in Example 2. This figure shows the heating weight change of each recovered product in Example 3.

[0010] The following describes an example embodiment of this disclosure. These descriptions and examples are illustrative and do not limit the scope of the invention. In numerical ranges described stepwise in this specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Also, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the value shown in the example.

[0011] In this specification, each component may contain multiple types of the corresponding substance. Furthermore, when referring to the amount of each component in a composition, if multiple types of the substance corresponding to that component are present in the composition, unless otherwise specified, it refers to the total amount of those multiple types of substances present in the composition. Also, "room temperature" means 25°C, and "normal pressure" means 1 atmosphere.

[0012] <Method for dissolving and precipitating polymer compounds> The method for dissolving and precipitating polymer compounds according to the present disclosure includes the steps of: separating phase 1 and phase 2 in a phase-separated state by heating a mixed solvent consisting of component A, component B which is immiscible with component A, and component C which is miscible with both component A and component B, and exhibiting temperature-dependent phase change behavior, to a temperature below the phase change temperature; dissolving a polymer compound in either phase 1 or phase 2, which is a good solvent for the polymer compound, to obtain a solution containing the polymer compound; and adding either phase 1 or phase 2, which is a poor solvent for the polymer compound, to the solution and precipitating the polymer compound by heating to a temperature above the phase change temperature.

[0013] As mentioned above, the invention described in Patent Document 1 is only applicable to polyolefins in which the xylene phase, a nonpolar solvent, acts as a good solvent and the ethylene carbonate phase, a nonprotic polar solvent, acts as a poor solvent. This presents a problem in that it is difficult to apply to polymer compounds that require a combination of a protic solvent and a nonpolar solvent for the good and poor solvent roles. The dissolution-precipitation method for polymer compounds according to this disclosure utilizes the fact that temperature-dependent phase change behavior occurs by adjusting the composition by combining two specific solvents and a miscible solvent with both, and, as with the prior art, solvent reuse without distillation is possible in the polymer dissolution-precipitation process. Furthermore, the dissolution-precipitation method for polymer compounds according to this disclosure can be applied to the dissolution-precipitation of polymer compounds other than polyolefins, such as polyacrylates and polyamides, by selecting a nonpolar solvent and a protic solvent as constituent components, and unwanted solvent solidification can be avoided by selecting a low-melting-point solvent as a constituent component.

[0014] This disclosure describes a technique for dissolving and precipitating polymer compounds using a solvent system that exhibits UCST-type phase transition behavior as shown in Figure 1. A solvent system exhibiting UCST-type phase transition behavior separates into two phases at temperatures below the phase transition temperature and becomes a miscible single phase at temperatures above the phase transition temperature. Examples of solvent systems exhibiting such behavior include mixed systems of two components, such as the xylene-ethylene carbonate system. In the polymer compound dissolution and precipitation method according to this disclosure, UCST-type phase transition behavior is induced in a solvent system combining three components A, B, and C, and this is utilized for the dissolution and precipitation of polymer compounds. Figure 2 shows the relationship between each component. Component A and Component B are immiscible with each other, while Component C is miscible with both Component A and Component B. As the proportion of component B increases, the separation properties improve, and conversely, as the proportion of component C increases, the miscibility improves. By utilizing this property and adjusting the composition of components A, B, and C, it is possible to create a system that exhibits a UCST-type phase change behavior, which is intermediate between miscibility and miscibility. An example of the relationship between the composition of components A, B, and C and their miscibility is shown in Figure 3. In the figure, A to C represent components A to C, respectively, Bration represents the mass ratio of component B to component A, and Critio represents the mass ratio of component C to component A.

[0015] Next, Figure 4 shows the dissolution-precipitation flow of a polymer compound using a mixed system of components A, B, and C. First, the mixed system of components A, B, and C is subjected to liquid-liquid separation below the phase change temperature, and the polymer compound is added to the separated phase, which acts as a good solvent for the polymer compound, and dissolved. The processing temperature at this time is arbitrary, and the optimal value varies depending on the type of polymer compound and the composition of the separated phase. By adding the separated phase, which acts as a poor solvent for the polymer compound, to the obtained polymer compound solution and adjusting it to above the phase change temperature, the solvent system becomes miscible, the solubility of the polymer compound decreases, and the polymer compound precipitates. The precipitated polymer compound is subjected to solid-liquid separation, and the remaining solvent system is adjusted to below the phase change temperature and subjected to liquid-liquid separation again, making the solvent reusable. Other solid-liquid separation operations include filtration, centrifugation, and decantation.

[0016] Next, Figure 5 shows the purification flow of a polymer compound using a mixed system of components A, B, and C. By dissolving the polymer compound containing impurities in the same manner as in Figure 4, removing the liberated impurities, and then precipitating the polymer compound again in the same manner as in Figure 4, the polymer compound can be purified. Methods for removing impurities may include using adsorbents, filtration, centrifugation, or decantation.

[0017] Component A is a liquid component. If component A is solid at room temperature, it may be liquefied by heating before use. Examples of component A include aromatic hydrocarbons, alcohols, esters, carbonates, ethers, ketones, halogenated hydrocarbons, etc. Among these, component A is preferably an aromatic hydrocarbon from the viewpoint of dissolving various polymer compounds. Examples of aromatic hydrocarbons include benzene, ethylbenzene, toluene, xylene, mesitylene, cymene, cumene, pseudocumene, etc. Examples of alcohols include aliphatic alcohols with 4 or more carbon atoms (butanol, hexanol, etc.) and aromatic alcohols (benzyl alcohol, etc.). Examples of esters include aliphatic carboxylic acid esters (methyl acetate, ethyl acetate, butyl acetate, vinyl acetate, ethyl propionate, ethyl butyrate, etc.). Examples of carbonates include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, etc. Examples of ethers include diethyl ether, ethyl propyl ether, and ethyl isopropyl ether. Examples of ketones include methyl ethyl ketone, pentanone, hexanone, heptanone, and cyclohexanone. Examples of halogenated hydrocarbons include dichloroethane and trichloromethane. Component A preferably contains xylene, mesitylene, cymene, cumene, or pseudocumene, and more preferably xylene, from the viewpoint of dissolving or precipitating various polymer compounds.

[0018] Component B can be either a liquid or a solid. If component B is a solid at room temperature, it may be liquefied by heating before use. Preferably, component B is a molecule having two or more OH groups in its molecule. Examples of molecules having two or more OH groups in their molecule include water and polyhydric alcohols. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, butanediol, diethylene glycol, dipropylene glycol, and glycerin. In particular, from the viewpoint of dissolving or precipitating various polymer compounds, component B preferably contains at least one selected from the group consisting of water, dihydric alcohols, and glycerin, more preferably contains at least one selected from the group consisting of water, ethylene glycol, and 1,2-propanediol, and especially preferably contains 1,2-propanediol.

[0019] Component C is a liquid component. If component C is solid at room temperature, it may be liquefied by heating before use. Component C is preferably at least one selected from the group consisting of monohydric alcohols with 3 or fewer carbon atoms, ketones, cyclic carbonates with 2 or more carbon atoms that do not have an acyclic alkyl group, and cyclic ethers with 2 or more carbon atoms that do not have an acyclic alkyl group. Examples of monohydric alcohols with 3 or fewer carbon atoms include methanol, ethanol, 1-propanol, and 2-propanol. Examples of ketones include acetone, 2-butanone, and cyclohexanone. Examples of cyclic carbonates with 2 or more carbon atoms that do not have an acyclic alkyl group include propylene carbonate, ethylene carbonate, and vinylene carbonate. Examples of cyclic ethers with 2 or more carbon atoms that do not have an acyclic alkyl group include 1,4-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, and tetrahydropyran. In particular, from the viewpoint of dissolving or precipitating various polymer compounds, component C preferably contains at least one selected from the group consisting of methanol, ethanol, 2-propanol, acetone, ethylene carbonate, propylene carbonate, and 1,4-dioxane, and more preferably contains at least one selected from the group consisting of methanol, ethanol, 2-propanol, acetone, propylene carbonate, and 1,4-dioxane.

[0020] Components A, B, and C do not necessarily have to be single substances; they may contain multiple substances within the range that satisfies the relationship shown in Figure 2. Furthermore, the phase change temperature of the mixed system of components A, B, and C can be adjusted according to the composition, but from the viewpoint of use in the dissolution and precipitation of polymer compounds, the phase change temperature is preferably in the range of 10°C to 140°C at 1 atm. If the phase change temperature is 0°C or higher, the cooling energy during the liquid-liquid separation operation is small, and if it is 140°C or lower, the heating energy during the precipitation operation is small. Moreover, the composition of components A, B, and C is preferably such that the ratio of component B to component A (amount of component B / amount of component A) is 0.1 to 2.0, and the ratio of component C to component A (amount of component C / amount of component A) is also preferably 0.1 to 2.0. Within the above ranges, the imbalance in the proportion of each separated phase during liquid-liquid separation is suppressed, and both good solvent phases and poor solvent phases are obtained in appropriate proportions, making it suitable for use in the dissolution and precipitation of polymer compounds.

[0021] As the polymer compound, various polymer compounds that can be dissolved in the mixed solvent system of components A, B, and C can be used without particular limitation. Among these, polyolefins, polyacrylates, or polyamides are preferred as the polymer compound from the viewpoint of ease of purification.

[0022] The details of the dissolution-precipitation method for polymer compounds related to this disclosure will be further explained below.

[0023] <Separation Step> The dissolution-precipitation method of a polymer compound according to the present disclosure includes a step of separating phase 1 and phase 2 in a phase-separated state by setting a mixed solvent, which consists of component A, component B which is immiscible with component A, and component C which is miscible with both component A and component B and exhibits temperature-dependent phase change behavior, to a temperature below the phase change temperature.

[0024] The mixing ratio of components A, B, and C in the mixed solvent is not particularly limited, as long as it is possible to exhibit temperature-dependent phase change behavior. The amount of component B relative to component A (amount of component B / amount of component A) is preferably 0.05 to 4 by mass ratio, more preferably 0.1 to 3, even more preferably 0.1 to 2.0, and particularly preferably 0.10 to 1.00, from the viewpoint of ease of purification and the production ratio of each phase. The amount of component C relative to component A (amount of component C / amount of component A) is preferably 0.05 to 4 by mass ratio, more preferably 0.1 to 3, even more preferably 0.1 to 2.0, and particularly preferably 0.10 to 1.00, from the viewpoint of ease of purification and the production ratio of each phase. The total amount of components B and C relative to component A (total amount of components B and C / amount of component A) is preferably 0.1 to 5, more preferably 0.2 to 4, even more preferably 1.0 to 3.5, and particularly preferably 1.00 to 2.00, in terms of mass ratio, from the viewpoint of ease of purification and the production ratio of each phase.

[0025] There are no particular restrictions on the phase change temperature of the mixed solvent, but from the viewpoint of energy efficiency and ease of handling, it is preferably 0°C to 150°C, more preferably 20°C to 120°C, and particularly preferably 40°C to 90°C.

[0026] Phase 1 and Phase 2 may be either good or poor solvents for the polymer compound. The volume ratio of Phase 1 to Phase 2 (Phase 1 / Phase 2) in the phase-separated state is preferably 0.1 to 10, and more preferably 0.2 to 5. In the separation step, it is not necessary to completely separate Phase 1 and Phase 2; the portion near the interface between Phase 1 and Phase 2 may be removed or recovered and reused. There are no particular restrictions on the separation method in the separation step; well-known methods such as using a separatory funnel or decantation can be employed. There are no particular restrictions on temperature control in the separation step; it can be appropriately performed using known methods.

[0027] <Step to obtain a dissolution solution> The dissolution-precipitation method for a polymer compound according to this disclosure includes the step of dissolving the polymer compound in either phase 1 or phase 2, which is a good solvent for the polymer compound, to obtain a dissolution solution containing the polymer compound. The step of obtaining the dissolution solution is preferably carried out at a temperature below the phase change temperature in the separation step. There are no particular restrictions on the amount of phase 1 or phase 2 used in the step of obtaining the dissolution solution; any amount sufficient to sufficiently dissolve the polymer compound used is acceptable. From the viewpoint of purification, it is preferable to use a larger amount of phase 1 or phase 2, but from the viewpoint of the amount of polymer compound recovered, it is preferable to use a smaller amount that is sufficient to dissolve the entire amount of polymer compound.

[0028] If the aforementioned dissolution solution contains insoluble matter other than the polymer compound, the dissolution-precipitation method of the polymer compound according to this disclosure preferably further includes a step of removing the insoluble matter other than the polymer compound. There are no particular limitations on the method of removing the insoluble matter, and well-known methods such as using adsorbents, filtration, centrifugation, and decantation can be employed.

[0029] <Precipitation Step> The dissolution-precipitation method for a polymer compound according to this disclosure includes the step of adding either phase 1 or phase 2, which is a poor solvent for the polymer compound, to the dissolution and precipitating the polymer compound at a temperature exceeding the phase change temperature. In the precipitation step, the unused phase 1 or phase 2, opposite to the phase 1 or phase 2 used in the step of obtaining the dissolution, is used as the poor solvent for the polymer compound. There are no particular restrictions on the amount of phase 1 or phase 2 used in the precipitation step, as long as it is enough to precipitate the polymer compound. From the viewpoint of purification, it is preferable to use a larger amount of phase 1 or phase 2, but from the viewpoint of the amount of polymer compound recovered, it is preferable to use a smaller amount. The temperature in the precipitation step should be a temperature exceeding the phase change temperature, but from the viewpoint of energy efficiency, it is preferable to be above the phase change temperature and below the phase change temperature + 50°C, and more preferably above the phase change temperature and below the phase change temperature + 30°C.

[0030] The polymer compound precipitated in the aforementioned precipitation step can be separated by known methods such as filtration, centrifugation, and decantation. The obtained polymer compound may also be washed, dried, or otherwise subjected to known methods.

[0031] (Method for recovering good solvent phase and poor solvent phase) The method for recovering a good solvent phase and a poor solvent phase according to the present disclosure includes, after the precipitation step in the dissolution-precipitation method of a polymer compound according to the present disclosure, a step of separating the polymer compound from the solvent, and a step of cooling the solvent to below the phase change temperature to separate the liquid and recover the good solvent phase and the poor solvent phase, respectively.

[0032] The separation method in the step of separating the polymer compound from the solvent can be a known method, such as filtration, centrifugation, or decantation. Furthermore, it is preferable to carry out the step of separating the polymer compound from the solvent at a temperature exceeding the phase change temperature. There are no particular restrictions on the recovery method in the recovery step, and well-known methods such as using a separatory funnel or decantation can be employed.

[0033] (Method for purifying polymer compounds) The method for purifying polymer compounds according to this disclosure includes, after the precipitation step in the dissolution-precipitation method for polymer compounds according to this disclosure, a step of separating the polymer compound from the solvent, a step of dissolving the separated polymer compound in a solvent other than the solvent and removing the liberated impurities, and a step of precipitating the polymer compound from the solution from which the impurities have been removed. The step of separating the polymer compound from the solvent can be carried out in the same manner as described above. The other solvent in the step of removing impurities is not particularly limited as long as the polymer compound is soluble in it. As the other solvent, phase 1 or phase 2, which are good solvents for the polymer compound, may be used, or other good solvents may be used. There are no particular limitations on the method of removing impurities in the step of removing impurities, and well-known methods such as using adsorbents, filtration, centrifugation, decantation, etc., can be employed. There are no particular limitations on the precipitation method in the step of precipitating the polymer compound from the solution from which the impurities have been removed, and known methods can be used, such as adding a poor solvent or precipitating by changing the temperature. The precipitated polymer compounds can be separated by known methods such as filtration, centrifugation, and decantation. The obtained polymer compounds may also be washed, dried, or otherwise processed using known methods.

[0034] The present disclosure will be further described below with reference to examples, but this disclosure is not limited to these examples. The examples were carried out under normal pressure.

[0035] <Materials Used> ・Glass fiber reinforced polypropylene (R-300G, manufactured by Prime Polymer Co., Ltd.) ・Glass fiber reinforced polyamide (CM1011G-45, manufactured by Toray Industries, Inc.) ・Polyethylene (ultzex ​​20199J, manufactured by Prime Polymer Co., Ltd.) ・Polymethyl methacrylate (M0088, manufactured by Tokyo Chemical Industry Co., Ltd.) ・Xylene (244-00081, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ・Methanol (131-01823, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ・Ethanol (057-00451, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ・2-Propanol (168-24855, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ・Acetone (019-00353, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) • Propylene carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product code 161-25205) • 1,4-Dioxane (manufactured by Tokyo Chemical Industries, Ltd., product code D0860) • Ethylene glycol (manufactured by Tokyo Chemical Industries, Ltd., product code E1015) • 1,2-Propanediol (manufactured by Tokyo Chemical Industries, Ltd., product code P0485) • Distilled water

[0036] (Example 1: Observation of Phase Change Temperatures for Different Compositions of Components A, B, and C) This example shows how UCST-type phase change behavior can be achieved by adjusting the compositions of components A, B, and C. Xylene was used as component A, distilled water, ethylene glycol, and 1,2-propanediol as component B, and methanol, ethanol, 2-propanol, acetone, propylene carbonate, and 1,4-dioxane as component C. Mixed solutions were prepared with mass ratios of components B and C to component A ranging from approximately 0.1 to 2.0. After heating the resulting solutions until mixed, they were stirred while being air-cooled at 20°C, and the change in brightness of the entire solution was observed. When the solution was stirred in a phase-separated state, the entire solution became cloudy and its brightness increased. The solution temperature at which the brightness increased was recorded as the phase change temperature. Table 1 shows the composition and phase change temperature for each level. From these results, it can be confirmed that UCST-type phase change behavior can be achieved by adjusting the compositions of components A, B, and C, and that the phase change temperature can also be controlled.

[0037]

[0038] (Example 2: Purification Treatment of Glass Fiber Reinforced Polypropylene) This example describes the application of the method to the separation and purification of polymer compound components and fiber components in glass fiber reinforced polypropylene. Xylene (25.0 g), methanol (25.0 g), and distilled water (3.5 g) were mixed and separated at 20°C. Glass fiber reinforced polypropylene (0.5 g) was added to the obtained lower layer liquid and stirred at 125°C for 20 minutes. The obtained solution was filtered to separate the free glass fibers. When the filtrate was added to the upper layer liquid and stirred at 75°C, the precipitation of polypropylene was confirmed. This polypropylene precipitate was filtered off, and the remaining filtrate was left to stand at 20°C. The phase-separated filtrate was then separated at 20°C, and glass fiber reinforced polypropylene (0.5 g) was added again to the lower layer liquid and treated in the same manner as the first time. Subsequently, each recovered material was heated at 500°C for 2 hours under atmospheric pressure, and the weight change of each was measured. The yield of each recovered material is shown in Table 2, and the weight change after heating is shown in Figure 6. The weight loss rate of the polypropylene precipitate was over 99%, while the weight loss rate of the glass fibers was less than 20%. Since organic matter gasifies and disappears at 500°C, it is thought that most of the polypropylene precipitate is organic matter. Furthermore, it is thought that only a small amount of organic matter adheres to the glass fibers, and separation of the polymer compound component and the fiber component was confirmed.

[0039]

[0040] (Example 3: Purification Treatment of Glass Fiber Reinforced Polyamide) This example describes the application of the method to the separation and purification of polymer compound components and fiber components in glass fiber reinforced polyamide. Xylene (25.0 g), 1,2-propanediol (25.0 g), and propylene carbonate (2.7 g) were mixed and separated at 20°C. Glass fiber reinforced polyamide (0.5 g) was added to the obtained lower layer and stirred at 160°C for 40 minutes. The obtained solution was filtered to separate the free glass fibers. When the filtrate was added to the upper layer and stirred at 125°C, the precipitation of polyamide was confirmed. This polyamide precipitate was filtered off and the remaining filtrate was left to stand at 20°C. The phase-separated filtrate was then separated at 20°C, and glass fiber reinforced polyamide (0.5 g) was added again to the lower layer and treated in the same manner as the first time. Subsequently, each recovered material was heated at 500°C for 2 hours under air and the weight change of each was measured. The yield of each recovered material is shown in Table 3, and the weight change after heating is shown in Figure 7. The weight loss rate of the polyamide precipitate was 98% or more, while the weight loss rate of the glass fibers was 4% or less. Since organic matter gasifies and disappears at 500°C, it is thought that most of the polyamide precipitate is organic matter. Furthermore, it is thought that only a small amount of organic matter adheres to the glass fibers, and separation of the polymer compound component and the fiber component was confirmed.

[0041]

[0042] (Example 4: Polyethylene Dissolution-Precipitation Test) An example of application to the dissolution-precipitation of polyethylene is described below. Xylene (10.0 g), methanol (10.0 g), and distilled water (1.5 g) were mixed and separated at 20°C. Polyethylene (0.1 g) was added to the obtained lower layer and heated and stirred at 105°C for 30 minutes. When the obtained solution was added to the upper layer and stirred at 75°C, polyethylene precipitation was confirmed. The yield of polyethylene precipitate after filtration and air drying was 0.1 g.

[0043] (Example 5: Dissolution-Precipitation Test of Methyl Polymethacrylate) An example applied to the dissolution-precipitation of methyl polymethacrylate will be described. Xylene (10.0 g), methanol (20.0 g), and distilled water (3.0 g) were mixed and separated at 10°C. Methyl polymethacrylate (0.1 g) was added to the obtained lower layer liquid and heated at 80°C for 80 minutes. When the obtained solution was added to the upper layer liquid and stirred at 60°C, precipitation of methyl polymethacrylate was confirmed. The yield of the methyl polymethacrylate precipitate separated by filtration and air-dried was 0.1 g.

[0044] From the above, it can be seen that the dissolution-precipitation method of the polymer compound of this example can perform dissolution-precipitation treatments of various polymer compounds.

[0045] The disclosure of Japanese Patent Application No. 2025-011725 filed on January 27, 2025 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference.

Claims

1. A method for dissolving and precipitating a polymer compound, comprising the steps of: separating phase 1 and phase 2 in a phase-separated state by heating a mixed solvent consisting of component A, component B which is immiscible with component A, and component C which is miscible with both component A and component B, and exhibiting temperature-dependent phase change behavior, to a temperature below the phase change temperature; dissolving a polymer compound in either phase 1 or phase 2, which is a good solvent for the polymer compound, to obtain a solution containing the polymer compound; and adding either phase 1 or phase 2, which is a poor solvent for the polymer compound, to the solution and precipitating the polymer compound by heating to a temperature above the phase change temperature.

2. The method for dissolving and precipitating a polymer compound according to claim 1, wherein component A is an aromatic hydrocarbon and component B is a molecule having two or more OH groups in its molecule.

3. The method for dissolving and precipitating a polymer compound according to claim 1, wherein component C is at least one selected from the group consisting of monohydric alcohols having 3 or less carbon atoms, ketones, cyclic carbonates having 2 or more carbon atoms but lacking an acyclic alkyl group, and cyclic ethers having 2 or more carbon atoms but lacking an acyclic alkyl group.

4. The method for dissolving and precipitating a polymer compound according to claim 1, wherein the temperature-dependent phase change behavior exhibits behavior that shows an upper limit critical eutectic temperature, and the critical temperature at 1 atmosphere is in the range of 10°C to 140°C.

5. The method for dissolving and precipitating a polymer compound according to claim 1, wherein component A comprises xylene, component B comprises at least one selected from the group consisting of water, ethylene glycol, and 1,2-propanediol, and component C comprises at least one selected from the group consisting of methanol, ethanol, 2-propanol, acetone, propylene carbonate, and 1,4-dioxane.

6. The method for dissolving and precipitating a polymer compound according to claim 1, wherein the polymer compound is a polyolefin, a polyacrylate, or a polyamide.

7. The method for dissolving and precipitating a polymer compound according to claim 1, wherein the mass ratio of component B to component A is 0.1 or more and 2.0 or less.

8. The method for dissolving and precipitating a polymer compound according to claim 1, wherein the mass ratio of component C to component A is 0.1 or more and 2.0 or less.

9. A method for recovering a good solvent phase and a poor solvent phase, comprising the steps of: separating the polymer compound from the solvent after the precipitation step in the dissolution-precipitation method of a polymer compound according to any one of claims 1 to 8; and cooling the solvent to below the phase change temperature to separate the liquid and recover the good solvent phase and the poor solvent phase, respectively.

10. A method for purifying a polymer compound, comprising the steps of: separating the polymer compound from a solvent after the precipitation step in the dissolution-precipitation method for a polymer compound according to any one of claims 1 to 8; dissolving the separated polymer compound in a solvent other than the solvent and removing the liberated impurities; and precipitating the polymer compound from the dissolved solution from which the impurities have been removed.

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