Purification method of non-aqueous solvent and management method of non-aqueous solvent

Abstract

To provide a purification method of a non-aqueous solvent capable of reducing content of at least one of a boron compound and a silicon compound in a non-aqueous solvent containing at least one of the boron compound and the silicon compound as impurities, the boron compound and the silicon compound being difficult to be removed by distillation.SOLUTION: In a purification method of a non-aqueous solvent, non-aqueous solvent containing at least one of a silicon compound and a boron compound is purified so as to reduce a content of at least one of the silicon compound and the boron compound in the non-aqueous solvent. The method includes a purification step of passing the non-aqueous solvent through an ion exchanger in a clean room.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for purifying a non-aqueous solvent, which removes impurities that are difficult to remove by distillation from the non-aqueous solvent, and a method for managing the non-aqueous solvent using the non-aqueous solvent purified by the purification method. [Background technology]

[0002] To reduce the amount of impurities contained in a solvent, techniques such as adsorption using ion exchange resins, activated carbon, or zeolites, distillation, or membrane separation are commonly used. However, in the trace range of ppb order or less, applicable techniques are limited due to issues with contamination and impurity removal performance. Distillation (precision distillation and non-boiling distillation) is a common method for purifying high-purity chemicals, but some impurities cannot be removed by distillation. For example, when purifying an organic solvent by distillation, the difference in boiling point between the organic solvent and water can be utilized to separate and purify ionic impurities with high affinity for water from the easily volatile organic solvent. However, as described in Non-Patent Document 1, boron is difficult to reduce by distillation because it easily volatilizes along with the organic solvent. Similar issues exist for silicon. Patent Document 1 also describes that while fine particles in the air are reduced in clean rooms, contamination by boron compounds is likely to occur. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-322716 [Patent Document 2] Patent application No. 2023-056154 [Non-patent literature]

[0004] [Non-Patent Document 1] "Distillation Separation of Boron," Analytical Chemistry, 1963, Vol. 12, No. 2, pp. 120-125 Summary of the Invention [Problem to be solved by the invention]

[0005] ICP and ICP-MS are used to analyze trace amounts of impurities, but because almost all reagents contain boron as an impurity (see Non-Patent Document 1), analyzing such trace amounts of boron and silicon is not easy, and there are problems such as limitations on the measurable concentration range. Thus, there is currently a need for a method for reducing the content of boron and silicon in a solvent, and in particular for the development of a method for purifying a solvent with a further reduced content of boron and silicon that can be suitably used for analytical purposes.

[0006] The present invention aims to provide a method for purifying a non-aqueous solvent, which can reduce the content of at least one of a boron compound and a silicon compound in a non-aqueous solvent containing at least one of the boron compound and the silicon compound as an impurity that is difficult to remove by distillation. Another object of the present invention is to provide a method for managing a target non-aqueous solvent using the non-aqueous solvent obtained by the above purification method. [Means for solving the problem]

[0007] The present invention provides a method for purifying a non-aqueous solvent containing at least one of a silicon compound and a boron compound, thereby reducing the content of at least one of the silicon compound and the boron compound in the non-aqueous solvent, the method comprising a purification step of passing the non-aqueous solvent through an ion exchanger in a clean room.

[0008] The present invention also provides a method for managing a non-aqueous solvent, characterized in that the purified non-aqueous solvent obtained by the above-mentioned purification method is used as a blank solution when measuring the concentration of at least one of a silicon compound and a boron compound in the target non-aqueous solvent, thereby performing quality control of the target non-aqueous solvent. [Effects of the Invention]

[0009] According to the present invention, it is possible to reduce the content of at least one of boron compounds and silicon compounds in a non-aqueous solvent containing at least one of the boron compounds and silicon compounds as impurities that are difficult to remove by distillation. Furthermore, the purified non-aqueous solvent obtained by the present invention is a non-aqueous solvent having an extremely low content of at least one of the boron compounds and silicon compounds. Therefore, by using the non-aqueous solvent as a blank solution when measuring the concentration of the boron compounds and / or silicon compounds in a target non-aqueous solvent, highly accurate analysis can be performed. As a result, stable analysis of the impurity concentration in the target non-aqueous solvent becomes possible, and the quality control of the target non-aqueous solvent can be performed appropriately. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a solvent purification unit according to a first embodiment used in one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a solvent purification unit according to a second embodiment used in one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Method for purifying non-aqueous solvent> The method for purifying a nonaqueous solvent according to the present invention purifies a nonaqueous solvent containing at least one of a silicon compound and a boron compound as an impurity, thereby reducing the content of at least one of the silicon compound and the boron compound in the nonaqueous solvent. Furthermore, the method for purifying a nonaqueous solvent according to the present invention includes a purification step of passing the nonaqueous solvent through an ion exchanger in a clean room. As described above, impurities such as silicon compounds and boron compounds contained in the solvent are difficult to remove by distillation. Furthermore, it is known that boron compounds are subject to environmental contamination in clean rooms. However, according to the present invention, by purifying the nonaqueous solvent using an ion exchanger in a clean room, the amount of at least one of the silicon compounds and the boron compounds in the nonaqueous solvent can be reduced to a level on the order of ppb or less while suppressing environmental contamination. The inventors believe that the reason why environmental contamination can be suppressed in the present invention is as follows. This is because the ion exchanger used for purification is isolated from the outside air, there is little contamination from storage containers, etc., and the ion exchanger itself has the ability to adsorb silicon compounds and boron compounds.

[0012] [Non-aqueous solvent] The nonaqueous solvent is an organic solvent, and is not particularly limited as long as it contains at least one of a silicon compound and a boron compound as an impurity. Examples of organic solvents include methanol, ethanol, isopropyl alcohol (IPA), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), N-methylpyrrolidone, methyl ethyl ketone, methyl isobutyl ketone, ethyl lactate (EL), butyl lactate (NBL), γ-butyrolactone (GBL), and isobutyl propionate (IBP). One organic solvent may be used alone, or two or more organic solvents may be used in combination, such as a mixed solvent of PGME and PGMEA. The nonaqueous solvent may be a mixed solvent of an organic solvent and water. While the present invention relates to a method for purifying a nonaqueous solvent, the method for purifying a nonaqueous solvent according to the present invention can also be applied to water. In the following description, the term "nonaqueous solvent" may also be simply referred to as "solvent."

[0013] The purified nonaqueous solvent obtained by the method of the present invention (also referred to as "purified nonaqueous solvent" or "purified solvent") contains an extremely low content of at least one of silicon compounds and boron compounds, making it particularly suitable as a blank solution used when measuring the content of these impurities in a target nonaqueous solvent. Therefore, any solvent that can be used as a blank solution can be used as the nonaqueous solvent in the present invention. The blank solution is, for example, a calibration curve blank solution having the same composition as a calibration curve standard solution used to prepare a calibration curve when performing elemental analysis by inductively coupled plasma mass spectrometry (ICP-MS). That is, when measuring the metal concentration in a target solvent using ICP-MS, a standard solution to which a known concentration of metal has been added is diluted in several stages with a blank solution that is the same type of solvent as the target solvent to prepare a calibration curve. The metal concentration in the target solvent is set so that it falls within the calibration curve concentration range. This method is called the absolute calibration curve method, and it is important that the blank solution does not contain the target metal. This is because a high concentration of the target metal in the blank solution increases the background concentration, thereby raising the lower limit of quantitation. For these reasons, the metal impurity content in blank solutions used in trace metal analysis of solvents by ICP-MS must be at a level of the order of ppb or less.

[0014] [impurities] The silicon compounds and boron compounds contained as impurities in the non-aqueous solvent are not particularly limited. The silicon compounds may be any silicon-containing compounds, and may be either organic silicon compounds or inorganic silicon compounds. The boron compounds may be any boron-containing compounds. The non-aqueous solvent may contain any impurities other than the silicon compounds and boron compounds.

[0015] [Clean room] The higher the cleanliness class of the clean room, the better from the viewpoint of suppressing contamination from the environment. The clean room used in the present invention is preferably a clean room having a cleanliness of Class 8 or higher (equivalent to Class 100,000 of the US Federal Standard) as defined by the international standard ISO14644-1:2015 established by the International Organization for Standardization. The cleanliness of the clean room as defined by the international standard represents the number of suspended particles of 0.1 μm or more present in a volume space of 1 cubic meter. For example, Class 8 means that the upper limit of the number of particles is 10 8 pieces / m 3 This means that

[0016] [Ion exchanger] In the present invention, purification of the non-aqueous solvent does not require distillation, but is carried out by passing the non-aqueous solvent through an ion exchanger. The ion exchanger is not limited as long as it has ion exchange groups. The ion exchanger can be one or more selected from the group consisting of cation exchangers and anion exchangers. Specifically, the ion exchanger can be one or more selected from the group consisting of granular ion exchange resins, monolithic ion exchangers, pulverized molded products of granular ion exchange resins, ion exchange fibers, and ion adsorption membranes. The cation exchanger may be a strongly acidic cation exchanger having strongly acidic cation exchange groups, a weakly acidic cation exchanger having weakly acidic cation exchange groups, or a chelate-type exchanger having chelate groups. The anion exchanger may be a strongly basic anion exchanger having strongly basic anion exchange groups, a weakly basic anion exchanger having weakly basic anion exchange groups, or a chelate-type exchanger having chelate groups. However, from the viewpoint of further reducing the amount of at least one of the impurities of silicon compounds and boron compounds, the ion exchanger preferably contains an ion exchanger having at least an anion exchange group, more preferably an ion exchanger having a strongly basic anion exchange group, and from the viewpoint of versatility, the ion exchanger is preferably a granular ion exchange resin.

[0017] From the perspective of impurity removal efficiency and contamination suppression, the ion exchanger used in the purification process preferably contains 0.2 mg / L or less of metal impurities and elutes 3 mg / L or less of total metal impurities when a 25-volume volume of hydrochloric acid with a concentration of 5% by mass or less is passed through it. Boron elution from common reagents and resins (plastics, filters, ion exchangers) is also a problem. However, using a sufficiently purified ion exchanger like this can suppress boron elution from the ion exchanger. Note that "25-volume volume" hydrochloric acid means passing a volume of hydrochloric acid 25 times the volume of the ion exchanger. The unit " / LR" means "per 1 L of volume of ion exchanger in a wet state." The wet state refers to the state in which the ion exchanger is immersed in water. The wet state volume can be determined by measuring the volume of the ion exchanger immersed in water using a measuring instrument such as a graduated cylinder. Here, the ion exchanger in a wet state is obtained by contacting the ion exchanger with the atmosphere at 25° C. and a relative humidity of 100% for 15 minutes or more.

[0018] An ion exchanger containing 0.2 mg / L or less of metal impurities and eluting 3 mg / L or less of total metal impurities when 25 volumes of hydrochloric acid with a concentration of 5% by mass or less are passed through the ion exchanger can be prepared by any method using a mineral acid solution. Examples of mineral acid solutions include aqueous solutions of hydrochloric acid, sulfuric acid, and nitric acid. Commercially available ion exchangers containing 0.2 mg / L or less of metal impurities and eluting 3 mg / L or less of total metal impurities when 25 volumes of hydrochloric acid with a concentration of 5% by mass or less are passed through the ion exchanger. Examples of commercially available ion exchangers include granular ion exchange resins in the Allite DS series (trade name, manufactured by Organo Corporation).

[0019] (Granular ion exchange resin) Granular ion exchange resins (hereinafter also referred to simply as "ion exchange resins") include cation exchange resins and anion exchange resins. The ion exchange resin may be a chelate resin. The ion exchange resin preferably contains at least an anion exchange resin, more preferably a strongly basic anion exchange resin. One type of ion exchange resin may be used alone, or two or more types may be used in combination. A cation exchange resin and an anion exchange resin may also be used in combination. When a cation exchange resin and an anion exchange resin are used in combination, the cation exchange resin and the anion exchange resin may be packed as a mixed bed in one packing device, or may be packed as single beds in separate packing devices. Furthermore, a cation exchange resin and / or anion exchange resin may be used in combination with a chelate resin.

[0020] The base of the cation exchange resin is preferably a styrene-divinylbenzene copolymer. The base of the cation exchange resin may have any of a gel, macroporous, and porous structure. The ionic form of the cation exchange resin is preferably the H-type from the viewpoint of impurity removal. The cation exchange resin may be a strongly acidic cation exchange resin or a weakly acidic cation exchange resin. However, since strongly acidic cation exchange resins may decompose some ester-based organic solvents, it is preferable to reduce the amount of ion exchange resin used depending on the type of solvent to be purified, or to use a cation exchange resin that does not decompose the solvent to be purified. For example, when purifying a solvent containing TMAH or an amine, using an amine-type or TMA-type cation exchange resin can suppress changes in the ionic composition of the solvent to be purified.

[0021] The ion exchange capacity of the H-form strongly acidic cation exchange resin in a wet state is preferably 0.5 eq / LR or more, more preferably 1.0 eq / LR or more. The higher the ion exchange capacity of the H-form strongly acidic cation exchange resin in a wet state, the better, and the capacity may be selected appropriately. The average particle size (harmonic mean diameter) of the H-form strongly acidic cation exchange resin is preferably 200 to 900 μm, more preferably 300 to 700 μm. The average particle size is a value measured using a laser diffraction particle size analyzer.

[0022] Examples of strongly acidic cation exchange resins include Amberlite IR120B, IR124, 200CT, HPR1200, and HPR1006NNC (all trade names), and Amberjet 1020, 1024, 1060, and 1220 (all trade names) manufactured by DuPont de Nemours; and Diaion SK104, SK1B, SK110, SK112, PK208, PK212L, PK216, and PK222 (all trade names) manufactured by Mitsubishi Chemical Corporation. 218, PK220, PK228, UBK08, UBK10, and UBK12 (all trade names); Allite DS-1, DS-4 (all trade names), and Amberlyst 15JS-HG·DRY (trade name) manufactured by Organo Corporation; C100, C100E, C120E, C100x10, C100x12MB, C150, C160, and SGC650 (all trade names) manufactured by Purolite Corporation; and Lewatit Monoplus S108H, Monoplus SP112, and S1668 (all trade names) manufactured by Lanxess AG, but are not limited thereto. Examples of weakly acidic cation exchange resins include, but are not limited to, Amberlite FPC3500 and IRC76 (all trade names) manufactured by DuPont de Nemours; Diaion WK10, WK11, WK100, and WK40L (all trade names) manufactured by Mitsubishi Chemical Corporation; C104, C106, C107E, C115E, and SSTC104 (all trade names) manufactured by Purolite Co., Ltd.; and Lewatit CNP80WS (trade name) manufactured by Lanxess AG.

[0023] The base material of the anion exchange resin is preferably a styrene-divinylbenzene copolymer. The base material of the anion exchange resin may have any of a gel, macroporous, and porous structure. Examples of the ionic form of the anion exchange resin include OH, Cl, F, organic acid, carbonate, bicarbonate, and mineral acid forms. From the viewpoint of impurity removal, the OH form is preferred. The anion exchange resin may be a strongly basic anion exchange resin or a weakly basic anion exchange resin. However, for solvents in which decomposition or chemical reaction occurs when using an OH-form strongly basic anion exchange resin, it is preferable to use a carbonate or bicarbonate anion exchange resin, or to use a carbonate or bicarbonate anion exchange resin in combination with an OH-form strongly basic anion exchange resin. By using an OH-form strongly basic anion exchange resin in combination with a carbonate or bicarbonate anion exchange resin, the amount of the OH-form strongly basic anion exchange resin used can be reduced, and the contact time between the OH-form strongly basic anion exchange resin and the solvent can be shortened. When a strongly basic anion exchange resin in the OH form is used to purify a hydrolyzable solvent such as PGMEA, the contact time between the resin and the solvent may be shortened to suppress the progression of hydrolysis, for example by setting the solvent flow rate through the resin to SV10 L / L-resin-hour or more.

[0024] The anion exchange resin preferably has an ion exchange capacity in a wet state of 0.5 to 2.0 eq / LR, more preferably 0.9 to 2.0 eq / LR, and has an average particle size (harmonic mean diameter) of 200 to 900 μm, more preferably 300 to 800 μm.

[0025] Examples of anion exchange resins include Amberlite IRA900, IRA402, IRA96SB, IRA98, and IRA743 (all trade names) manufactured by DuPont de Nemours; Amberjet 4400, 4002, and 4010 (all trade names); AmberSep IRA743 (trade name); and Diaion UBA120, PA306S, PA308, PA312, PA316, PA318L, and WA2 (trade names) manufactured by Mitsubishi Chemical Corporation. 1J, and WA30 (all trade names); Allite DS-2, DS-5, DS-6, and A-P5100 (all trade names) manufactured by Organo Corporation; Amberlyst B20-HG·DRY (trade name); A400, A600, SGA550, A500, A501P, A502PS, A503, A100, A103S, A110, A111S, and A133S (all trade names) manufactured by Purolite Co., Ltd.; and Lewatit Monoplus M500, Monoplus M800, MP62WS, and Monoplus MP64 (all trade names) manufactured by Lanxess AG, but are not limited to these.

[0026] When a cation exchange resin and anion exchange resin are used as a mixed bed, commercially available mixed bed resins can be used, including, but not limited to, Orlite DS-3 and DS-7 (trade names) and Amberlyst MSPS2-1 DRY (trade name) manufactured by Organo Corporation.

[0027] The functional group of the chelating resin is not particularly limited as long as it can coordinate with a metal ion to form a chelate, and examples thereof include functional groups having an amino group, such as an iminodiacetic acid group, an aminomethylphosphate group, or an iminopropionic acid group, and a thiol group. Examples of the chelating resin matrix include a styrene-divinylbenzene copolymer. The chelating resin matrix may have any of a gel type, a macroporous type, and a porous type structure. The ionic form of the chelating resin is preferably the H type. The exchange capacity of the H type chelating resin is preferably 0.5 to 2.5 eq / LR, more preferably 1.0 to 2.5 eq / LR. The average particle size (harmonic mean diameter) of the H type chelating resin is not particularly limited, but is preferably 300 to 1000 μm, more preferably 500 to 800 μm.

[0028] The H-type chelating resin can be prepared by contacting a metal ion-type chelating resin with a mineral acid such as hydrochloric acid. The method for contacting the mineral acid is not particularly limited, and the contacting method, contact temperature, contact time, etc. are appropriately selected. Examples of metal ion chelating resins include Amberlite IRC747UPS, IRC748, GT74, M4195, and M4196UPS (all trade names) manufactured by DuPont de Nemours; CR-10 and CR-11 (all trade names) manufactured by Mitsubishi Chemical Corporation; Duolite C-467 (trade name) manufactured by Sumika Chemtex Co., Ltd.; MC-700 (trade name) manufactured by Sumitomo Chemical Co., Ltd.; Lewatit TP207, Lewatit TP208, and Lewatit TP260 (all trade names) manufactured by Lanxess AG; S930 and S950 (all trade names) manufactured by Purolite Co., Ltd.; and Allite DS-21 and DS-22 (all trade names) manufactured by Organo Corporation.

[0029] (Monolithic ion exchanger) Monolithic ion exchangers (organic porous ion exchangers) include organic porous cation exchangers with cation-exchange groups, organic porous anion exchangers with anion-exchange groups, and organic porous chelate exchangers with chelating functional groups. The exchange capacity of organic porous cation exchangers is preferably 1 to 3 mg equivalents (eq) / mL (dry state), more preferably 1.5 to 3 mg equivalents / mL (dry state). The exchange capacity of organic porous anion exchangers is preferably 1 to 6 mg equivalents / mL (dry state), more preferably 2 to 5 mg equivalents / mL (dry state). The exchange capacity of H-type organic porous chelate exchangers is preferably 0.3 to 2 mg equivalents / mL (wet state), more preferably 1 to 2 mg equivalents / mL (wet state).

[0030] (Molded product made by crushing granular ion exchange resin) A molded product made by crushing granular ion exchange resin refers to a product made by mixing crushed ion exchange resin with a support such as polyethylene and molding it into a block. The shape may be such that it can be packed into a column or resin tower, or such that the solvent flows from the outside to the inside, like a filter. If the required flow rate of solvent can be processed at a given pressure or less, the crushed ion exchange resin may be placed in a container or the like without a support and molded. Commercially available examples of such molded products include the 3M Metal Ion Removal Filter MIP series, SCP series, and APP series (all trade names, manufactured by 3M).

[0031] (ion exchange fiber) Examples of ion-exchange fibers include cation-exchange fibers and anion-exchange fibers, which have a structure in which functional groups (ion-exchange groups) are introduced into a fiber substrate. The substrate for the ion-exchange fiber can be appropriately selected from the viewpoints of physical strength and chemical resistance. Specifically, polyester, polyethylene, polypropylene, polyolefin, polyacrylonitrile, polyamide, polyimide, or fluororesin is preferred. Known ion-exchange fibers can be appropriately selected and used.

[0032] (ion adsorption membrane) Examples of ion adsorption membranes include those having a porous membrane material (base material) with cation exchange groups or anion exchange groups introduced onto the surface of the membrane material, and those made by processing fibers having cation exchange groups or anion exchange groups into a membrane. Examples of base materials constituting the ion adsorption membrane include one or more selected from polyethylene, polypropylene, cellulose, nylon, polystyrene, fluororesin, polytetrafluoroethylene, polyethersulfone, polyamide, polyimide, etc. Known ion adsorption membranes can be appropriately selected and used.

[0033] The purification step of passing a non-aqueous solvent through an ion exchanger can be carried out by a known method. For example, the non-aqueous solvent to be purified is passed through an ion exchanger packed in an ion exchanger-packed container (purification device). The passage rate (SV) of the non-aqueous solvent when passing it through is not particularly limited, but can be, for example, 0.1 to 50 L / L-resin-hour. The temperature of the non-aqueous solvent when passing it through the ion exchanger is not particularly limited, but is usually 0 to 50°C. The non-aqueous solvent to be purified may be filled in a solvent storage tank in advance, and then transferred from the solvent storage tank to the ion exchanger-packed container using a pressure-transfer device such as a pump.

[0034] The purification step of passing the non-aqueous solvent through the ion exchanger is preferably carried out in a sealed apparatus provided in a clean room from the viewpoint of preventing contamination from the environment. That is, the purification step is preferably carried out using a sealed apparatus including a purification device having an ion exchanger for purifying the non-aqueous solvent and a solvent storage tank for storing the non-aqueous solvent, the purification device and the solvent storage tank being connected by a connecting member such as a tube. This prevents the non-aqueous solvent and the ion exchanger before and after purification from coming into contact with the atmosphere during the purification of the non-aqueous solvent.

[0035] (Solvent purification unit) The sealed device may be a solvent purification unit including the purification device, the solvent storage tank, and a housing that houses the purification device and the solvent storage tank. The solvent purification unit will be described below with reference to the drawings. For the solvent purification unit, the description of the liquid purification unit described in Patent Document 2 may be referred to as appropriate.

[0036] First Embodiment FIG. 1 shows a schematic configuration of a solvent purification unit 1A according to a first embodiment. In FIG. 1, the flow of the solvent in the step of passing the solvent through an ion exchanger (purification step) is indicated by a thick solid line, and the flow of the pressurized gas is indicated by a thick dashed line. As shown in FIG. 1, the solvent purification unit 1A includes a purification device 3 having an ion exchanger and purifying the solvent, and a solvent storage tank 2 for storing the solvent to be supplied to the purification device 3. The purification device 3 may include an ion exchanger-packed device 4 having an ion exchanger, and a filter device 5 upstream and / or downstream thereof. In FIG. 1, the ion exchanger-packed device 4 and the filter device 5 are arranged in series on the first solvent supply pipe L1. Although not shown, multiple ion exchanger-packed devices 4 and / or multiple filter devices 5 may be arranged in parallel. The filter device 5 includes, for example, a microfiltration membrane or an ultrafiltration membrane. A filter having ion exchange groups may be used as the filter device 5. The solvent storage tank 2 is disposed upstream of the purification device 3, and the purification device 3 and the solvent storage tank 2 are connected by a first solvent supply pipe L1. The first solvent supply pipe L1 supplies the solvent in the solvent storage tank 2 to the purification device 3. The solvent purified by the purification device 3 is discharged to the outside of the housing 6 through a purified solvent discharge pipe L5 that passes through the housing 6.

[0037] The refining device 3 and the solvent storage tank 2 are housed in a housing 6. The refining device 3 and the solvent storage tank 2 contain an organic solvent, which is a flammable solvent. Therefore, the housing 6 is preferably made of a material that is strong, chemical-resistant, and explosion-proof. Specifically, the housing 6 is preferably made of metal or plastic, but may be made of other materials as long as they have sufficient strength, chemical resistance, and explosion-proof properties. An exhaust opening 6A is provided at the top of the housing 6. Note that the piping and parts described below are also housed in the housing 6 unless otherwise specified.

[0038] A first drain pipe L6 branches off from the first solvent supply pipe L1 and extends outside the housing 6. A second vent pipe L7 branches off from the first solvent supply pipe L1 between the ion exchanger packing device 4 and the filter device 5 and merges with the first drain pipe L6. The second vent pipe L7 is provided to exhaust air from the ion exchanger packing device 4 when refilling the ion exchanger packing device 4 with solvent after emptying it for maintenance or other purposes. The second vent pipe L7 can also be used to exhaust wastewater generated during initial cleaning, which is performed to remove air and particulate impurities from the ion exchangers. A three-way valve V4 is installed at the branch point of the second vent pipe L7 of the first solvent supply pipe L1 to switch between the process of exhausting air from the ion exchanger packing device 4 and the purification process.

[0039] A solvent supply unit 7 is provided outside the housing 6, and the solvent supply unit 7 is connected to the solvent storage tank 2 by a second solvent supply pipe L4 that passes through the housing 6. The second solvent supply pipe L4 supplies the solvent to the solvent storage tank 2. Note that by installing a pump (not shown) between the solvent supply unit 7 and the housing 6, the solvent can be sent from the solvent supply unit 7 to the solvent storage tank 2. The solvent is processed in batches, and a valve V1 provided on the second solvent supply pipe L4 remains closed until a certain amount of solvent stored in the solvent storage tank 2 has been processed in the purification device 3. The valve V1 is a manual valve, and an operating unit such as a handle (not shown) is provided outside the housing 6.

[0040] A pressurized gas supply unit 8 such as a cylinder is provided outside the housing 6, and the pressurized gas supply unit 8 is connected to the solvent storage tank 2 by a pressurized gas supply pipe L3 that penetrates the housing 6. The pressurized gas supply pipe L3 supplies pressurized gas to the solvent storage tank 2. The pressurized gas is used to pressurize the solvent in the solvent storage tank 2 and send it to the purification device 3. As the pressurized gas, an inert gas such as nitrogen gas or air is used. A valve V2 for controlling the supply of pressurized gas is provided in the pressurized gas supply pipe L3. An operation unit (not shown) for the valve V2 is provided outside the housing 6. The flow rate of the solvent supplied to the purification device 3 can be controlled by adjusting the supply pressure of the pressurized gas using the pressurized gas supply unit 8 or the valve V2.

[0041] The solvent storage tank 2 is provided with a first vent pipe L2 that communicates with the interior of the solvent storage tank 2 and extends upward from the solvent storage tank 2. The first vent pipe L2 is provided to exhaust air from the solvent storage tank 2 when refilling the solvent storage tank 2 with solvent (hereinafter also referred to as the "solvent refilling process"), but is also used to supply pressurized gas to the solvent storage tank 2 in the purification process. That is, in the purification process, pressurized gas is supplied to the solvent storage tank 2 through the pressurized gas supply pipe L3 and the first vent pipe L2. In addition, a three-way valve V3 is provided at the junction of the pressurized gas supply pipe L3 and the first vent pipe L2 to switch between the purification process and the solvent refilling process. The first vent pipe L2 is connected to a first drain pipe L6 (see *A in FIG. 1).

[0042] A drain pan 9 is installed at the bottom of the housing 6. A second drain pipe L8 connected to the drain pan 9 penetrates the housing 6 and extends outside the housing 6. The drain pan 9 is provided to collect and retain leaked solvent in the unlikely event of a solvent leak within the housing 6. The solvent leak location is not limited, and the drain pan 9 can leak from any container, device, or pipe containing the solvent. Therefore, the drain pan 9 is preferably installed so as to cover the entire bottom surface of the housing 6 so that it can be installed not only below the solvent storage tank 2, the ion exchanger packing device 4, and the filter device 5, but also below the pipe through which the solvent flows. The capacity of the drain pan 9 is preferably larger than the volume of the flammable solvent present within the housing 6. A waste tank (not shown) may be installed at the end of the second drain pipe L8 outside the housing 6, and the solvent accumulated in the drain pan 9 may be automatically or manually discharged into the waste tank.

[0043] The inner surfaces of the first solvent supply pipe L1, the second solvent supply pipe L4, and the purified solvent discharge pipe L5 are each made of fluororesin. Similarly, the inner surfaces of the solvent storage tank 2, the casing of the ion exchanger packing device 4, and the casing of the filter device 5 are also made of fluororesin. Because the raw solvent or purified solvent passes through these pipes, tanks, and casings, forming at least the solvent-contacting parts from fluororesin, which has excellent chemical resistance and is resistant to contamination, enables higher-purity purification, reducing impurity concentrations to ppb-order levels or below. Examples of fluororesin include perfluoroalkoxyalkane (PFA) and polytetrafluoroethylene (PTFE). Because no solvent flows through the pressurized gas supply pipe L3, the inner surfaces do not need to be made of fluororesin. The drain pan 9 and the first and second drain pipes L6 and L8 have solvent-contacting parts. However, if the discharged solvent is to be recovered and purified, it is preferable to form at least the solvent-contacting parts from fluororesin.

[0044] In FIG. 1, the opening 6A provided for exhaust is open, but from the viewpoint of further suppressing contamination from the environment, the opening 6A can be closed by any method during the purification process. Alternatively, the purification process can be performed while circulating an inert gas using the opening 6A. Furthermore, the purification process can be performed by creating a positive pressure inside the housing 6 by any method. The solvent storage tank 2, the purification device 3, the ion exchanger filling device 4, and the filter device 5 inside the housing 6 are connected to each other by various pipes, forming an entirely sealed structure.

[0045] The solvent purification unit 1A configured as described above operates as follows. In the purification step, pressurized gas is supplied from the pressurized gas supply unit 8 to the solvent storage tank 2 through the pressurized gas supply pipe L3 and the first vent pipe L2. The solvent stored in the solvent storage tank 2 is pressurized by the pressurized gas and sent to the purification device 3 (the ion exchanger packing device 4 and the filter device 5) through the first solvent supply pipe L1. The solvent is then purified in the purification device 3 by removing ionic substances and particulates, including at least one of boron compounds and silicon compounds. The purified solvent is discharged to the outside of the housing 6 through the purified solvent discharge pipe L5. The above purification step may be repeated two or more times.

[0046] When the solvent storage tank 2 is nearly empty, a solvent replenishment step is performed to replenish the solvent storage tank 2 with solvent for the next batch processing. Specifically, valve V2 is closed, valve V1 is opened, and solvent is supplied from the solvent supply unit 7 through the second solvent supply pipe L4 to the solvent storage tank 2. Air in the solvent storage tank 2 is purged through the first vent pipe L2 and replaced with solvent.

[0047] Second Embodiment Figure 2 shows a schematic configuration of a solvent purification unit 1B according to the second embodiment. In Figure 2, the flow of the solvent in the purification step (circulation operation) is indicated by a thick solid line, and the flow of the pressurized gas is indicated by a thick dashed line. Here, differences from the solvent purification unit 1A according to the first embodiment will be mainly described. Configurations and effects that are not described are the same as those of the first embodiment.

[0048] The solvent purification unit 1B connects the purification device 3 and the solvent storage tank 2 and includes a return pipe L9 that returns the purified solvent purified by the purification device 3 to the solvent storage tank 2. In other words, in the solvent purification unit 1B according to this embodiment, the solvent is purified while circulating along a circulation path consisting of the first solvent supply pipe L1 and the return pipe L9. To circulate the solvent, the solvent purification unit 1B includes a diaphragm pump 10. The diaphragm pump 10 is provided in the first solvent supply pipe L1 and delivers the solvent to the purification device 3. The diaphragm pump 10 is a type of positive displacement pump that discharges the solvent by moving a diaphragm using a pressurized gas, such as an inert gas such as nitrogen or air. Similar to the diaphragm pump, an air-operated valve that operates using pressurized gas may also be used. The pressurized gas is supplied to the diaphragm pump 10 from outside the housing 6 through the working fluid supply pipe L10. The diaphragm pump 10 is preferably a non-energized, air-driven pump. When pressurized gas such as an inert gas such as nitrogen or air is supplied, the diaphragm moves due to the pressure of the pressurized gas, reducing the volume of the pump chamber. When the supply of pressurized gas is stopped, the diaphragm retracts to expand the volume of the pump chamber. The liquid-contacting parts of the diaphragm pump 10, like the piping and casing, are preferably made of fluororesin. The solvent purification unit 1B has a control unit 11 for controlling the supply of the working fluid, and the control unit 11 is provided outside the housing 6. This eliminates the need for an electrical power supply inside the housing 6. The flow rate of the solvent supplied to the purification device 3 can be controlled by adjusting the supply pressure and supply timing of the working fluid in the control unit 11.

[0049] The solvent purification unit 1B configured as described above operates as follows. In the purification step, the working fluid is supplied to the diaphragm pump 10 through the working fluid supply pipe L10. The solvent is then purified while circulating along the circulation path (L1 and L9). After a predetermined time has passed, the supply of the working fluid is stopped, and a valve (not shown) is operated to switch the return pipe L9 to the purified solvent discharge pipe L5, and the purified solvent is discharged outside the housing 6. Thereafter, a solvent refilling step is performed to replenish the solvent storage tank 2 with solvent for the next batch processing. Specifically, the valve V1 is opened, and the solvent is supplied from the solvent supply unit 7 to the solvent storage tank 2 via the second solvent supply pipe L4.

[0050] As described above, the solvent purified using the solvent purification unit is discharged to the outside of the housing 6 through the purified solvent discharge pipe L5. From the viewpoint of preventing contamination of the purified solvent from the environment, it is preferable to minimize the time the purified solvent is exposed to the air before being transferred to a storage container. Furthermore, when various analyses are performed on the purified solvent, it is preferable to perform them in an environment where contamination can be prevented, such as in a clean room or under conditions where the solvent is not exposed to the air.

[0051] As described above, the purification method using an ion exchanger according to the present invention, unlike purification by distillation, can reduce the content of silicon compounds, such as organic silicon compounds and inorganic silicon compounds, and boron compounds, in a non-aqueous solvent. Purification using an ion exchanger is advantageous in that it can be completed in a shorter time than distillation and can be prepared immediately before use. Furthermore, ion exchangers are less susceptible to contamination from storage containers and the atmosphere, and can reduce the content of boron-containing impurities to the ppb order even in a clean room. Purifying a non-aqueous solvent using a solvent purification unit within a housing can further prevent the incorporation of fine particles, such as silicon compounds, and boron compounds into the non-aqueous solvent.

[0052] <Method for managing non-aqueous solvents> The nonaqueous solvent control method of the present invention is characterized by performing quality control of a target nonaqueous solvent by using a purified nonaqueous solvent obtained by the nonaqueous solvent purification method of the present invention as a blank solution when measuring the concentration of at least one of a silicon compound and a boron compound in the target nonaqueous solvent. While a blank solution with a concentration of the target element as close to zero as possible is considered preferable, a method for reducing the impurity concentration of silicon compounds and boron compounds in a solvent to ppb-order levels has not been known until now, and analyzing the concentration of silicon compounds and boron compounds in a solvent itself has been problematic. However, since the concentration of at least one of the silicon compounds and boron compounds in the purified nonaqueous solvent is extremely low, at the ppb-order level, using the purified nonaqueous solvent as a blank solution when measuring the concentration of at least one of the silicon compounds and boron compounds in the target nonaqueous solvent enables highly accurate analysis. In other words, the concentration of at least one of the impurities, i.e., silicon compounds and boron compounds, in the target nonaqueous solvent can be stably analyzed, thereby enabling appropriate quality control of a target nonaqueous solvent with reduced content of these impurities. The target nonaqueous solvent is the same type of solvent as the nonaqueous solvent to be purified. The purified nonaqueous solvent obtained by the solvent purification method according to the present invention can also be used as various chemical solutions used in semiconductor manufacturing processes. [Example]

[0053] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The apparatus, reagents, and ion exchangers used in the following examples and comparative examples are as follows.

[0054] <Device> Solvent storage tank 2: PFA pressure vessel (2L) Pump: Q Pump (product name, manufactured by Takumina Corporation) Ion exchanger packing device 4: PFA column (inner diameter 22 mm, capacity 90 mL x 1) Filter device 5: Optimizer D filter (product name, pore size 5 nm, manufactured by Entegris) Distillation apparatus: Non-boiling distillation apparatus (product name: Evapoclean, manufactured by IAS Co., Ltd.) Metal concentration analyzer: Agilent 8900 triple quadrupole (product name, manufactured by Agilent Technologies, Inc.)

[0055] <Reagents> Undiluted solution: IPA SE grade (product name, manufactured by Tokuyama Corporation) Stock solution: PGMEA (propylene glycol monomethyl ether acetate, trade name: PM Thinner, manufactured by Tokyo Ohka Kogyo Co., Ltd.) · Stock solution: Ultrapure water (Organo Corporation, A4 or higher grade as specified in JIS K055:1998) General-purpose mixed standard solution (including silicon compounds and boron compounds, product name: XSTC-8, manufactured by SPEX) Organosilicon compounds: C3H 10 OSi (trimethylsilanol, Fujifilm Wako Pure Chemical Industries, Ltd.)

[0056] <Ion exchanger> OH-type strong basic anion exchange resin (trade name: Orlite DS-2, manufactured by Organo Corporation, anion exchange capacity: 1.0 eq / LR) Carbonate-type strong basic anion exchange resin (trade name: Orlite A-P5100, manufactured by Organo Corporation, anion exchange capacity: 1.0 eq / LR) A mixed-bed resin consisting of an H-type strongly acidic cation exchange resin and an OH-type strongly basic anion exchange resin (trade name: Orlite DS-3, manufactured by Organo Corporation) Chelate resin (product name: Allite DS-21, manufactured by Organo Corporation) In addition, all of the above ion exchangers contain metal impurities in an amount of 0.2 mg / L or less, and when hydrochloric acid with a concentration of 5 mass% or less is passed through them at a volume ratio of 25 times, the total amount of metal impurities eluted is 3 mg / L or less.

[0057] [Examples 1 and 2] IPA simulants were prepared by adding either the general-purpose mixed standard solution (containing silicon and boron compounds) or the organosilicon compounds to IPA. Each IPA simulant was purified using an ion exchanger in the solvent purification unit 1A shown in Figure 1 according to the following procedure, and the silicon and boron concentrations in the simulants before and after purification were analyzed. The purification process and the measurement of impurity concentrations were both carried out in a clean room with a cleanliness level of 100,000 or higher (class 8 or higher as defined by the international standard ISO 14644-1:2015).

[0058] (purification process) In the solvent purification unit 1A, the pump was installed between the solvent supply unit 7 (prepared IPA simulant) and the housing 6, and the IPA simulant was pumped into the solvent storage tank 2. At this time, the gas in the solvent storage tank 2 was discharged to the outside of the system via the route L2 → V3 → *A. Next, the IPA simulant was passed from the solvent storage tank 2 through the ion exchanger packing device 4 filled with Orlite DS-2 and the filter device 5 at a rate of SV3 (3 L / L resin / hour). Compressed air was used as the pressurized gas for passing the simulant. After 20 times the resin volume of the IPA simulant had passed through, the treated solution was sampled and analyzed for silicon and boron concentrations. The blank solution used for the analysis was the above-mentioned IPA (raw solution without the addition of a general-purpose mixed standard solution, etc.), which was purified with resin by the same method as in Example 1. In this example, the purification process was carried out under sealed conditions, including filling the solvent storage tank 2 with the IPA simulant (pressurized delivery of the liquid in a sealed system) and passing the simulant through the ion exchanger packing device 4 and the filter device 5. The treatment liquid was exposed to the atmosphere (in a clean room) during the sampling process. The results are shown in Table 1. In Table 1, the silicon / boron concentrations after purification indicate the silicon / boron concentrations when the silicon / boron concentrations before purification are set at "100." Furthermore, for the silicon / boron concentrations before purification, the numbers in parentheses indicate the actually measured silicon / boron concentrations (ppb).

[0059] [Example 3] Except for using a mixture of Orlite DS-3 and Orlite DS-21 (volume ratio 1:1) as the ion exchanger, the purification process was carried out on the IPA simulant solution containing the general-purpose mixed standard solution in the same manner as in Example 1. The results are shown in Table 1.

[0060] [Comparative Examples 1 and 2] IPA simulants were prepared by adding the above-mentioned general-purpose mixed standard solution or organosilicon compounds to IPA. Each prepared IPA simulant was distilled at 60°C for 20 hours, and the resulting distillate was analyzed. The distillation was carried out under sealed conditions. The IPA simulant was exposed to the atmosphere during the process of transferring the pre-distillation IPA simulant to the distillation vessel and the process of transferring the distillate to an analytical vial. The results are shown in Table 1.

[0061] [Table 1]

[0062] As shown in Table 1, the purification according to the examples using an ion exchanger resulted in a higher impurity reduction effect than distillation purification in all simulated solutions. It was found that a high impurity reduction effect could be obtained even when an OH-type strongly basic anion exchange resin was used alone as the ion exchanger (Example 1). In Comparative Example 2, the silicon concentration was higher than before purification, suggesting the possibility that silicon was concentrated as a result of volatilization of volatile components by distillation.

[0063] [Example 4] Except for using a carbonate-type strongly basic anion exchange resin (Orlite A-P5100) as the ion exchanger, the purification process was carried out on the IPA simulant solution containing the general-purpose mixed standard solution in the same manner as in Example 1. The results are shown in Table 2 together with the results of Example 1 and Comparative Example 1.

[0064] [Table 2]

[0065] As shown in Table 2, according to the present invention, even when a carbonate-type strongly basic anion exchange resin is used, the concentrations of silicon compounds and boron compounds can be reduced, similar to the case of an OH-type strongly basic anion exchange resin.

[0066] [Examples 5 and 6] The above-mentioned general-purpose mixed standard solution was added to PGMEA to prepare a PGMEA simulation solution. The PGMEA simulation solution was purified in the same manner as in Example 1, using Orlite DS-2 (OH type) or Orlite A-P5100 (carbonate type) as the ion exchanger. The results are shown in Table 3.

[0067] Comparative Example 3 The PGMEA simulant prepared in Example 5 was distilled at 90-100°C for 20 hours, and the resulting distillate was analyzed. The distillation was carried out under sealed conditions. The PGMEA simulant was exposed to the atmosphere during the process of transferring the pre-distillation PGMEA simulant to a distillation vessel and the process of transferring the distillate to an analytical vial. The results are shown in Table 3.

[0068] [Table 3]

[0069] As shown in Table 3, it was found that the present invention can also be applied to PGMEA, a hydrolyzable solvent. Furthermore, the effect of reducing silicon compounds and boron compounds in the examples purified using an ion exchanger was superior to that in the case of distillation purification.

[0070] [Reference examples 1 and 2] A simulation solution was prepared by adding the above-mentioned general-purpose mixed standard solution to ultrapure water. Using Orlite DS-2 (OH type) or Orlite A-P5100 (carbonate type) as the ion exchanger, the simulation solution containing the above-mentioned general-purpose mixed standard solution was subjected to a purification process similar to that of Example 1. The results are shown in Table 4. As shown in Table 4, when the solvent was water, a certain degree of silicon compound reduction effect was observed using a strongly basic anion exchange resin in the OH type. On the other hand, when a strongly basic anion exchange resin in the carbonate type was used, almost no silicon compound reduction effect was observed.

[0071] [Table 4]

[0072] The present invention includes the following configurations. [Configuration 1] A method for purifying a non-aqueous solvent, comprising purifying a non-aqueous solvent containing at least one of a silicon compound and a boron compound to reduce the content of at least one of the silicon compound and the boron compound in the non-aqueous solvent, comprising: A method for purifying a non-aqueous solvent, comprising a purification step of passing the non-aqueous solvent through an ion exchanger in a clean room. [Configuration 2] 2. The method for purifying a non-aqueous solvent according to claim 1, wherein the purification step is carried out in a sealed device provided in the clean room. [Configuration 3] The sealing device is a purification device having the ion exchanger; a solvent storage tank for storing the non-aqueous solvent to be supplied to the purification device; a housing that houses the purification device and the solvent storage tank; 3. The method for purifying a non-aqueous solvent according to claim 2, wherein the solvent purification unit comprises: [Configuration 4] 4. The method for purifying a non-aqueous solvent according to any one of Aspects 1 to 3, wherein the ion exchanger comprises at least one selected from an OH-type anion exchange resin and a carbonate-type or bicarbonate-type anion exchange resin. [Configuration 5] 5. The method for purifying a non-aqueous solvent according to any one of Configurations 1 to 4, wherein the clean room has a cleanliness level of Class 8 or higher as defined by the international standard ISO14644-1:2015. [Configuration 6] A method for managing a non-aqueous solvent, characterized in that the purified non-aqueous solvent obtained by the purification method according to any one of aspects 1 to 5 is used as a blank solution when measuring the concentration of at least one of a silicon compound and a boron compound in the target non-aqueous solvent, thereby performing quality control of the target non-aqueous solvent. [Explanation of symbols]

[0073] 1 Solvent Purification Unit 2 Solvent storage tanks 3 Purification equipment 4. Ion exchanger filling device 5. Filter device 6. Housing 7 Solvent supply section 8. Pressurized gas supply section

Claims

1. A method for purifying a non-aqueous solvent, comprising purifying a non-aqueous solvent containing at least one of a silicon compound and a boron compound to reduce the content of at least one of the silicon compound and the boron compound in the non-aqueous solvent, comprising: A method for purifying a non-aqueous solvent, comprising a purification step of passing the non-aqueous solvent through an ion exchanger in a clean room.

2. The method for purifying a non-aqueous solvent according to claim 1 , wherein the purification step is carried out in a sealed device provided in the clean room.

3. The sealing device is a purification device having the ion exchanger; a solvent storage tank for storing the non-aqueous solvent to be supplied to the purification device; a housing that houses the purification device and the solvent storage tank; The method for purifying a non-aqueous solvent according to claim 2 , wherein the solvent purification unit comprises:

4. 2. The method for purifying a non-aqueous solvent according to claim 1, wherein the ion exchanger comprises at least one selected from an OH-type anion exchange resin and a carbonate-type or bicarbonate-type anion exchange resin.

5. The method for purifying a non-aqueous solvent according to claim 1, wherein the clean room has a cleanliness of class 8 or higher as defined by international standard ISO 14644-1: 2015.

6. A method for managing a non-aqueous solvent, characterized in that the purified non-aqueous solvent obtained by the purification method according to any one of claims 1 to 5 is used as a blank solution when measuring the concentration of at least one of a silicon compound and a boron compound in the target non-aqueous solvent, thereby performing quality control of the target non-aqueous solvent.

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