Method for purifying hydrolyzable organic solvents and method for producing resins for purifying hydrolyzable organic solvents

Abstract

Provided is a method for purifying a hydrolyzable organic solvent, the method making it possible to reduce the metal impurity concentration in the hydrolyzable organic solvent while suppressing the generation of acids. There is used a method for purifying a hydrolyzable organic solvent, the method being characterized by having a purification step for bringing a hydrolyzable organic solvent into contact with a cation exchange resin with which a chelate resin is mixed in a discretionary manner and purifying the hydrolyzable organic solvent, and moreover being characterized in that the volumetric ratio of the cation exchange resin relative to the total amount of the cation exchange resin and the discretionary chelate resin is 10-100%.

Description

[Technical field]

[0001] The present invention relates to a method for purifying a hydrolyzable organic solvent and a method for producing a resin for purifying a hydrolyzable organic solvent. [Background technology]

[0002] Semiconductors are manufactured through hundreds of complex processes. The line width of a semiconductor is determined by the photoresist process. The photoresist process includes a process of applying resist to a silicon wafer, an exposure process in which short-wavelength light is irradiated from a light source through a mask, a process of developing the photomask, a process of etching the parts without resist, and a process of stripping the resist. The resist applied to the wafer is a solvent in which an acid generator, a resin solution, and additives are dissolved in an organic solvent, and the organic solvent used is an ester-based organic solvent containing, as the main component, PGMEA (propylene glycol monomethyl ether acetate), ethyl lactate, or PGME (propylene glycol monomethyl ether), cyclohexanone, or the like.

[0003] In recent years, the requirements for semiconductor line width processing dimensions have become finer year by year. Refining the semiconductor line width promotes the miniaturization and high performance technology of IT devices. As the semiconductor line width becomes finer, the light source used in the exposure process has increased from g-line and i-line levels to short-wavelength ArF, EUV, and X-rays, and the amount of impurities in the organic solvent used around the resist coating is also set low. Among the impurities contained in the organic solvent, if there are a lot of metal elements remaining, the metal elements will adhere to the wafer and lead to a decrease in semiconductor performance. Therefore, metal elements are always listed as an item to be reduced.

[0004] On the other hand, it is known that ester-based organic solvents such as PGMEA used in semiconductor manufacturing undergo hydrolysis and generate acids when they come into contact with moisture, acid, or alkali. Therefore, in the purification of ester-based organic solvents, methods such as distillation and the use of chelating resins have been proposed as methods for removing metal impurities without generating acids.

[0005] Patent Document 1 describes a method for reducing metal ions in a photoresist composition by washing a chelating resin with deionized water, a mineral acid solution, and optionally an ammonium hydroxide solution, washing the resin with an organic solvent, mixing the resin with a photoresist composition, and heating and filtering the mixture. However, this method is insufficient in terms of removing Fe in particular.

[0006] In Patent Document 2, a resin solution for forming a photoresist film is passed through a filter substrate in which an ion exchange group and / or a chelating group is fixed to a polyolefin nonwoven fabric, and the flow rate (SV value) is kept at 10 h. -1 However, in Patent Document 2, only the Na concentration is described as the impurity concentration, and the inventors' investigation revealed that the removal of heavy metals such as Fe and Cr is inferior to the case where a chelating resin is used.

[0007] Patent Document 3 describes a method for removing metal impurities from a liquid to be treated such as PGMEA by using a chelating resin in which the amount of metal impurities contained therein has been reduced by a mineral acid solution. However, further investigation by the present inventors revealed that, depending on the liquid to be purified, heavy metals such as Fe and Cr may not be sufficiently removed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2000-501201 [Patent Document 2] JP 2013-061426 A [Patent Document 3] JP 2019-141800 A Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, an object of the present invention is to provide a method for producing a resin for purifying a hydrolyzable organic solvent, which is capable of reducing the concentration of metal impurities in a hydrolyzable organic solvent while suppressing the generation of acid, and a method for purifying a hydrolyzable organic solvent using the resin. [Means for solving the problem]

[0010] In view of the above problems, the present inventors conducted extensive research and found that by using a cation exchange resin optionally mixed with a chelating resin, it is possible to reduce metals that cannot be removed by the chelating resin alone while suppressing acid generation from a hydrolyzable organic solvent, and thus completed the present invention.

[0011] That is, the present invention is a method for purifying a hydrolyzable organic solvent, ,tree The method includes a purification step of purifying the hydrolyzable organic solvent by contacting the hydrolyzable organic solvent with a cation exchange resin mixed with a cation exchange resin, Before The volume ratio of the cation exchange resin to the total amount of the chelating resin is 10 to 10%. 50 % The hydrolyzable organic solvent is an ester-based organic solvent or a mixed solvent containing an ester-based organic solvent. The method for purifying a hydrolyzable organic solvent is characterized by:

[0012] The present invention also relates to a method for producing a resin for purifying a hydrolyzable organic solvent, comprising the steps of: Niki The method includes a step of mixing the cation exchange resin and the rate resin. Before The volume ratio of the cation exchange resin to the total amount of the chelating resin is 10 to 10%. 50 % The hydrolyzable organic solvent is an ester-based organic solvent or a mixed solvent containing an ester-based organic solvent. The present invention relates to a method for producing a resin for use in purifying a hydrolyzable organic solvent, the method being characterized by comprising the steps of: Effect of the Invention

[0013] According to the present invention, it is possible to provide a method for producing a resin for purifying a hydrolyzable organic solvent, which is capable of reducing the concentration of metal impurities in a hydrolyzable organic solvent while suppressing the generation of acid, and a method for purifying a hydrolyzable organic solvent using the resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The method for producing a resin for purifying a hydrolyzable organic solvent according to the present invention includes a step of mixing a chelating resin with a cation exchange resin. When a chelating resin is not used and only a cation exchange resin is used, the step can also be said to be a step of preparing a cation exchange resin. The method for purifying a hydrolyzable organic solvent according to the present invention includes a purification step of contacting a hydrolyzable organic solvent with a cation exchange resin optionally mixed with a chelating resin to purify the hydrolyzable organic solvent. The volume ratio of the cation exchange resin to the total amount of the cation exchange resin and the optional chelating resin is 10 to 100%.

[0015] (Hydrolyzable organic solvent) The hydrolyzable organic solvent, which is the liquid to be purified in the present invention, is an ester-based organic solvent that generates an acid by hydrolysis. The liquid to be purified in the present invention may be a mixed solvent of two or more organic solvents including at least an ester-based organic solvent. The liquid to be purified is not particularly limited, but includes ester-based organic solvents such as PGMEA (propylene glycol monomethyl ether acetate), ethylene glycol monoethyl ether acetate, ethyl-3-ethoxypropyl acetate, ethyl lactate, butyl lactate, butyl acetate, isopentyl acetate, and mixed solvents of these ester-based organic solvents with PGME (propylene glycol monomethyl ether), cyclohexanone, and the like. Among these, PGMEA or a mixed solvent of PGMEA / PGME is preferred. The ratio of PGMEA in the mixed solvent of PGMEA / PGME is not particularly limited, and can be appropriately adjusted according to the purpose.

[0016] The water concentration of the hydrolyzable organic solvent (before purification) used in the present invention is preferably 20 to 10,000 mg / L from the viewpoint of suppressing hydrolysis and stabilizing metal purification performance. The upper limit of the water concentration is preferably lower, more preferably 5,000 mg / L, and even more preferably 1,000 mg / L. The water concentration can be measured by the Karl Fischer method using, for example, a Karl Fischer volumetric moisture meter (product name: Aquacounter AQ-2200, manufactured by Hiranuma Sangyo Co., Ltd.).

[0017] (cation exchange resin) The ion exchange resin is obtained by introducing functional groups into a copolymer having a three-dimensional network structure obtained by copolymerizing, for example, styrene and divinylbenzene (DVB) in the presence of a catalyst and a dispersant. Examples of the cation exchange resin used in the present invention include a strongly acidic cation exchange resin having a sulfonic acid group (-SO3H) and a weakly acidic cation exchange resin having a carboxylic acid group (-COOH). The cation exchange resin may be either a transparent gel type having a small pore diameter, or a macrolitericular type (MR type) or a macroporous type (also called a porous type or high-porous type) having macropores having a large pore diameter. In the present invention, from the viewpoint of removing metals, a strongly acidic cation exchange resin is preferably used. Among them, from the viewpoint of the balance between the inhibition of acid generation and the metal removal performance, an MR type strongly acidic cation exchange resin is preferable. From the viewpoint of more effectively inhibiting acid generation, a highly crosslinked gel type strongly acidic cation exchange resin is preferable. The highly cross-linked gel-type strongly acidic cation exchange resin specifically refers to a gel-type strongly acidic cation exchange resin having a cross-linking degree of 16% to 24%.

[0018] The volume ratio of the cation exchange resin to the total amount of the cation exchange resin and any chelating resin described later is 10 to 100%, preferably 20 to 100%. Here, the ratio of 100% means that only the cation exchange resin is used. According to the purification method of the present invention, even when only the cation exchange resin is used, it is possible to reduce metal impurities in the purification target liquid while suppressing acid generation. From the viewpoint of more effectively suppressing acid generation, it is preferable to use the cation exchange resin and the chelating resin in a mixed bed or multiple beds. In that case, the volume ratio of the cation exchange resin to the total amount of the cation exchange resin and the chelating resin is preferably 10% to 50%, more preferably 10% to 33%.

[0019] Examples of the cation exchange resin used in the present invention include, but are not limited to, AMBERLITE (registered trademark) IRN99H (gel-type strongly acidic cation exchange resin, trade name, manufactured by DuPont), AMBERLITE (registered trademark) CR99 K / 350, TAPTEC (registered trademark) HCRS Na (all gel-type strongly acidic cation exchange resins, trade names, manufactured by DuPont), AMBERJET (registered trademark) 1060H (gel-type strongly acidic cation exchange resin, trade name, manufactured by Organo Corporation), ORLITE (registered trademark) DS-1 (gel-type strongly acidic cation exchange resin, trade name, manufactured by Organo Corporation), ORLITE (registered trademark) DS-4 (MR-type strongly acidic cation exchange resin, trade name, manufactured by Organo Corporation), etc. As the ion form of the cation exchange resin, from the viewpoint of metal removal, the hydrogen ion form (H form) is preferable. When using a resin in another ion form (for example, sodium ion form, potassium ion form, etc.), it is preferable to convert it to the H form in advance by a known method.

[0020] (chelating resin) In the present invention, the cation exchange resin can be mixed with a chelating resin as desired. When a chelating resin is mixed, the cation exchange resin and the chelating resin may be mixed or multiple beds. In either case, the effect of the present invention can be obtained. The chelating resin is a resin having a functional group (chelating group) capable of forming a chelate (complex) with a metal ion. The functional group is not particularly limited as long as it is a functional group capable of forming a chelate (complex) with a metal ion. Examples of the functional group include an aminomethyl phosphate group, an iminodiacetic acid group, a thiol group, and a polyamine group. From the viewpoint of selectivity for a plurality of metal species, the chelating resin preferably has an aminomethyl phosphate group or an iminodiacetic acid group as a functional group.

[0021] The ionic form of the chelating resin is preferably H-type. Examples of the chelating resin include, but are not limited to, AMBERSEP (registered trademark) IRC747UPS (trade name, manufactured by DuPont, chelating group: aminomethyl phosphate group), AMBERSEP (registered trademark) IRC748 (trade name, manufactured by DuPont, chelating group: iminodiacetic acid group), ORLITE (registered trademark) DS-21 (trade name, manufactured by Organo Corporation, chelating group: aminomethyl phosphate group), ORLITE (registered trademark) DS-22 (trade name, manufactured by Organo Corporation, chelating group: iminodiacetic acid group), DIAION (registered trademark) CR11 (trade name, manufactured by Mitsubishi Chemical Corporation, chelating group: iminodiacetic acid group), S930 (trade name, manufactured by Purolite Corporation, chelating group: iminodiacetic acid group), and S950 (trade name, manufactured by Purolite Corporation, chelating group: aminophosphoric acid group). When the ion form of the resin is the sodium ion form (Na form), the ion form can be converted from the Na form to the H form by a known method before use.

[0022] The chelating resin used in the present invention is preferably in the hydrogen ion form, and the amount of total metal impurities eluted when 25 volumes of hydrochloric acid having a concentration of 3% by mass are passed through the chelating resin is preferably 5 μg / mL-R or less. Such a commercially available product can also be used as the chelating resin. Here, "25 volumes" means that 25 volumes of hydrochloric acid are passed through the chelating resin. The unit " / mL-R" means "per mL of the volume of the chelating resin in the saturated equilibrium state." The saturated equilibrium state refers to a state in which the chelating resin is saturated by contacting it with the atmosphere at 25° C. and 100% relative humidity for 30 minutes or more. "Passing through hydrochloric acid" includes not only passing hydrochloric acid through the chelating resin, but also immersing the chelating resin in hydrochloric acid. The total amount of metal impurities per mL of chelating resin (μg / mL-R) can be calculated from the amount of each eluted metal impurity (μg / L), the volume of the eluent used for elution (L), and the volume of the chelating resin (mL) using the following formula. Total amount of metal impurities (μg / mL-R) = (amount of each metal impurity (μg / L) × volume of eluent (L)) / volume of chelating resin (mL)

[0023] The chelating resin having a total metal impurity content of 5 μg / mL-R or less can be obtained, for example, by the method described in Patent Document 3. That is, the method is a purification method in which a mineral acid solution containing 1 mg / L or less of metal impurities and having a concentration of 5 mass% or more is brought into contact with the chelating resin. This can reduce the total amount of metal impurities (particularly the amount of metals eluted such as Na, Ca, Mg, and Fe) eluted when 25 times the volume of hydrochloric acid having a concentration of 3 mass% is passed through the chelating resin to 5 μg / mL-R or less. By purifying a hydrolyzable organic solvent using such a chelating resin having a reduced amount of metal impurities, a high-purity hydrolyzable organic solvent containing less metal impurities can be obtained. As the mineral acid solution, hydrochloric acid, sulfuric acid, nitric acid, etc. can be used. When the above purification is performed using a Na-type chelating resin, the ion form is converted to the H-type by performing the above purification.

[0024] (anion exchange resin) As described above, in the present invention, a cation exchange resin and an optional chelating resin are mixed and used, but an anion exchange resin can also be used in combination. By using an anion exchange resin, acid generation can be reliably suppressed. Therefore, even when only a cation exchange resin is used or when other acid generation is a concern, it is possible to purify with more suppressed acid generation by using an anion exchange resin in combination. When an anion exchange resin is used, the amount of the anion exchange resin used can be, for example, 0.1 to 100% by volume with respect to the total amount of the cation exchange resin and the optional chelating resin.

[0025] Examples of anion exchange resins include strongly basic anion exchange resins having quaternary ammonium bases and weakly basic anion exchange resins having primary to tertiary amino groups. Examples of anion exchange resins include, but are not limited to, ORLITE (registered trademark) DS-2 (gel-type strongly basic anion exchange resin, trade name, manufactured by Organo Corporation), DS-5 (MR-type strongly basic anion exchange resin, trade name, manufactured by Organo Corporation), and DS-6 (MR-type weakly basic anion exchange resin, trade name, manufactured by Organo Corporation). Among these, MR-type anion exchange resins are preferred.

[0026] The cation exchange resin, any chelating resin, and any anion exchange resin (hereinafter, these are also collectively referred to as "ion exchange resins") may be pretreated, as necessary, before being used in the purification of the hydrolyzable organic solvent. That is, the purification method according to the present invention may have, before the purification step, a pretreatment step in which the cation exchange resin, any chelating resin, and any anion exchange resin are pretreated to suppress the elution of water from the resin.

[0027] Examples of the pretreatment method include contacting the hydrolyzable organic solvent to be purified with an ion exchange resin, or contacting the ion exchange resin with a pretreatment organic solvent having a higher dielectric constant at 25° C. than the hydrolyzable organic solvent to be purified. Specifically, a method of passing the hydrolyzable organic solvent to be purified through a column packed with an ion exchange resin before use in purification and continuing the passage until the water concentration in the solvent at the inlet and outlet of the column becomes approximately the same can be mentioned. In addition, a method of passing a pretreatment organic solvent having a higher dielectric constant at 25° C. than the hydrolyzable organic solvent to be purified through a column packed with an ion exchange resin before use in purification and continuing the passage until the water concentration in the solvent at the inlet and outlet of the column becomes approximately the same can be mentioned. In this case, after passing the pretreatment organic solvent, the hydrolyzable organic solvent to be purified may be passed through the column until the water concentration in the solvent at the inlet and outlet of the column becomes approximately the same. As the pretreatment organic solvent, an alcohol such as methanol or ethanol having a dielectric constant of 20 or more at 25° C. is preferably used.

[0028] Another pretreatment method for suppressing water elution from the resin is to place a heat-resistant container filled with ion exchange resin inside a dryer and heat (dry) for several hours. The drying conditions can be set to an appropriate temperature and time from 50°C to 120°C for 1 hour to 24 hours depending on the type of ion exchange resin. By carrying out this treatment, the water content in the ion exchange resin can be reduced to 10 mass% or less. The drying method can be any of normal pressure, reduced pressure, and vacuum drying, but reduced pressure or vacuum drying is preferred because of the short drying time and high efficiency. The water content of the ion exchange resin can be calculated using the following formula. Moisture content (mass%) = ((mass (g) of resin heated using a dryer - mass (g) of resin completely dried using a heat drying type moisture meter) / mass (g) of resin heated using a dryer) x 100

[0029] Here, in the above formula, the resin heated by the dryer is obtained by heating the resin as described above (water content is 10% by mass or less). The resin heated by the dryer is then stored or moved so as to avoid moisture from the air being mixed in until it is measured by the heat-drying moisture meter. The resin is then placed on a heat-drying moisture meter and completely dried at 105°C for several minutes to several tens of minutes to obtain a resin completely dried by the heat-drying moisture meter. As the heat-drying moisture meter, for example, MX-50 (trade name) manufactured by A&D Co., Ltd. can be used. In order to increase the accuracy of the measurement, 5 g or more of the resin before drying is sampled and measured.

[0030] The method for contacting the hydrolyzable organic solvent with the ion exchange resin is not particularly limited, and examples thereof include a batch treatment method and a continuous liquid passing treatment method using a column. Of these, the continuous liquid passing treatment method is preferred from the viewpoints of operability and efficiency.

[0031] In the continuous liquid passing treatment method, the ion exchange resin is packed in a purification tower such as a column. The height of the resin packed bed in the purification tower is not particularly limited and can be, for example, 100 to 1500 mm. Next, the hydrolyzable organic solvent is added to the purification tower at a rate of, for example, SV (space velocity, h -1 The hydrolyzable organic solvent is passed through the ion exchange resin at a bed volume of 2 to 20, and 2 to 100 BV is passed through the ion exchange resin. From the viewpoint of removing metals, the hydrolyzable organic solvent is preferably passed through the ion exchange resin at a bed volume of 2 to 20, and more preferably at a bed volume of 5 to 10. The direction of the passage of the hydrolyzable organic solvent may be either downward or upward. By passing the hydrolyzable organic solvent through the ion exchange resin in this manner, metal impurities in the hydrolyzable organic solvent are adsorbed by the ion exchange resin and removed.

[0032] Next, the batch processing method will be described. First, the ion exchange resin is filled in a reaction tank equipped with a stirrer. Next, the hydrolyzable organic solvent is filled in the reaction tank. The volume ratio is not particularly limited, but a volume of 1 resin to 2 to 200 organic solvent is suitable. Then, the mixture is left for, for example, 0.5 to 24 hours. After leaving the mixture, the stirrer is operated to mix the resin and the organic solvent uniformly. The stirring speed and stirring time may be appropriately determined depending on the size of the reaction tank, the amount of processing, etc. After the stirring is completed, filtration or the like is performed to separate the resin and the hydrolyzable organic solvent, thereby removing metal impurities and obtaining a purified hydrolyzable organic solvent.

[0033] In addition, when the ion exchange resin is subjected to the above-mentioned pretreatment for suppressing water elution from the resin before being used for purification of the hydrolyzable organic solvent, the step of purifying the hydrolyzable organic solvent by contacting the ion exchange resin with the hydrolyzable organic solvent can be carried out using the container such as a column used for the pretreatment as it is.

[0034] The purification method according to the present invention is mainly to purify the hydrolyzable organic solvent by continuous operation, that is, in the purification step, after the purification (passing) of the hydrolyzable organic solvent to be purified is started, the passing of the liquid is continuously performed without stopping midway until the purification is completed. However, the purification of the hydrolyzable organic solvent can also be performed by intermittent operation. When the purification of the hydrolyzable organic solvent is performed by intermittent operation, the hydrolysis of the organic solvent may proceed due to moisture from the outside or functional groups from the resin inside the test system, and moisture or acid may be generated. Therefore, when performing the purification by intermittent operation, it is preferable that the purification method according to the present invention has a blowing step in which the hydrolyzable organic solvent eluted from the outlet of the purification column filled with a cation exchange resin, an optional chelating resin, and an optional anion exchange resin is discharged outside a storage tank for storing the hydrolyzable organic solvent after purification for a certain period of time after the start of the purification step. For example, when the passage of the hydrolyzable organic solvent is stopped for 30 minutes or more after the start of the purification step, the hydrolyzable organic solvent eluted from the outlet of the purification tower is discharged outside the storage tank at 0.5 BV or more relative to the amount of ion exchange resin (cation exchange resin, any chelating resin, and any anion exchange resin) as a blowing step, and then the purification step is resumed. By providing the blowing step, it is possible to reduce the moisture and acid generated during the operation stop. The blow amount in the blowing step (the amount of the hydrolyzable organic solvent discharged outside the system) can be set in advance based on the operation stop time, the moisture amount in the hydrolyzable organic solvent at the outlet of the purification tower, the acid concentration, and the resistivity value. Alternatively, it is possible to set by online monitoring that automatically stops the blowing step and switches to the purification step when the resistivity value reaches a preset value. Note that even when the purification of the hydrolyzable organic solvent is performed by continuous operation, the above blowing step can be performed as necessary.

[0035] According to the purification method of the present invention, since the generation of acid from the hydrolyzable organic solvent is suppressed, the pH of the hydrolyzable organic solvent after the purification step can be kept near neutral. Specifically, the pH of the hydrolyzable organic solvent after the purification step can be set to 5 to 7. However, depending on the type of hydrolyzable organic solvent, the pH may be, for example, 4 or less.

[0036] According to the purification method of the present invention, the concentration of each metal in the hydrolyzable organic solvent can be reduced by 70% by mass or more, preferably 80% by mass or more in the purification step. Examples of metal impurities contained in the hydrolyzable organic solvent include Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Ag, Cd, Sn, Ba, and Pb.

[0037] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. It should be noted that "Example 5" should be read as "Reference Example 5." EXAMPLES

[0038] The methods for measuring the metal concentration, acetic acid concentration and water concentration are as follows.

[0039] (metal concentration) Metal concentrations (ng / L) were measured using an Agilent 8900 triple quadrupole ICP-MS (trade name, manufactured by Agilent Technologies, Inc.).

[0040] (Acetic acid concentration) The acetic acid concentration (ppm by mass) was measured using a capillary electrophoresis system (product name: Agilent 7100, manufactured by Otsuka Electronics Co., Ltd.).

[0041] (moisture concentration) The water concentration was measured by the Karl Fischer method using a Karl Fischer volumetric moisture meter (product name: Aquacounter AQ-2200, manufactured by Hiranuma Sangyo Co., Ltd.).

[0042] (Ion exchange resin) Details of each ion exchange resin used in the following examples are as follows. ORLITE (registered trademark) DS-21 (trade name, manufactured by Organo Corporation): chelating resin, chelating group: aminomethyl phosphate group ORLITE (registered trademark) DS-4 (trade name, manufactured by Organo Corporation): MR type strong acid cation exchange resin, ion exchange group: sulfonic acid group ORLITE (registered trademark) DS-1 (trade name, manufactured by Organo Corporation): gel-type strong acid cation exchange resin, ion exchange group: sulfonic acid group, cross-linking degree: standard AMBERLITE® CR99 K / 350 (trade name, manufactured by DuPont): gel-type strong acid cation exchange resin, low cross-linking degree AMBERLITE® IRN99H (trade name, manufactured by DuPont): gel-type strong acid cation exchange resin, high degree of cross-linking ORLITE (registered trademark) DS-6 (trade name, manufactured by Organo Corporation): MR type weakly basic anion exchange resin

[0043] [Comparative Example 1, Examples 1 to 5: Comparison of Mixed Bed Ratios] (Purification of PGMEA) A PFA resin column (inner diameter: 16 mm, height: 300 mm) was filled with chelating resin ORLITE (registered trademark) DS-21 and MR type strong acid cation exchange resin ORLITE (registered trademark) DS-4, with the mixed bed ratio (volume ratio) of the cation exchange resins shown in Table 1, so that the total volume was 36 mL. It was confirmed that the total amount of metal impurities eluted when 3% by mass of hydrochloric acid was passed through the chelating resin at a volume ratio of 25 times was 5 μg / mL-R or less. As a pretreatment, PGMEA (trade name: PM Thinner, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was passed through the column with SV5 until the water concentration in the PGMEA at the column inlet and the column outlet reached the same level, thereby removing the water in the resin. It was also confirmed that the water in the resin can be removed by passing, instead of PGMEA, methanol, which has a higher relative dielectric constant at 25 ° C. than PGMEA, in the pretreatment. Next, 20 BV of PGMEA was passed through the pretreated resin at SV5 to carry out the purification process. The PGMEA before purification (stock solution) and the PGMEA at the column outlet after purification were collected, and the Cr concentration, acetic acid concentration, and water concentration were measured. The results are shown in Table 1. Regarding the generated acetic acid, up to 5 mg / L (absolute value) was within the measurement error range, meaning that it can be considered that there was almost no generation of acetic acid. Also, the Cr and acetic acid concentrations in the stock solution differ in each example, but this is due to differences in the lots of the stock solution.

[0044] [Table 1]

[0045] As shown in Table 1, in Examples 1 to 5 in which the mixed bed ratio of the cation exchange resin was 10% to 100%, the Cr concentration in the purified PGMEA was less than 15 ng / L, and metal removal was efficiently performed while suppressing the generation of acetic acid. In particular, in Examples 1 to 4 in which a mixed bed of a chelating resin and a cation exchange resin was used, the generation of acetic acid was almost completely suppressed. On the other hand, in Comparative Example 1 in which the mixed bed ratio of the cation exchange resin was 0%, i.e., only a chelating resin was used, the Cr removal rate in the purified PGMEA was 55%, indicating that metal removal was not sufficient.

[0046] [Examples 6-7: Comparison of Cr removal performance depending on the type of strongly acidic cation exchange resin] PGMEA was purified in the same manner as in Example 3, except that ORLITE (registered trademark) DS-1 (gel-type strongly acidic cation exchange resin, degree of crosslinking: standard) and AMBERLITE (registered trademark) CR99 K / 350 (gel-type strongly acidic cation exchange resin, degree of crosslinking: low, K-form converted to H-form) were used as the strongly acidic cation exchange resin (mixed bed ratio: 25% by volume) to be mixed with the chelating resin. PGMEA (raw solution) before purification and PGMEA at the column outlet after purification were collected, and the Cr concentration and water concentration were measured. The results are shown in Table 2 together with those of Example 3.

[0047] [Table 2]

[0048] As shown in Table 2, it was found that DS-4, an MR-type strongly acidic cation exchange resin, had particularly superior metal removal performance compared to DS-1, a gel-type strongly acidic cation exchange resin, and CR99 K / 350, a gel-type small-particle strongly acidic cation exchange resin.

[0049] [Examples 8 to 10: Comparison of acetic acid generation due to differences in crosslinking degree] PGMEA was purified in the same manner as in Example 3, except that AMBERLITE® IRN99H (high cross-linking degree), ORLITE® DS-1 (standard cross-linking degree), and AMBERLITE® CR99 K / 350 (low cross-linking degree, K-form converted to H-form) were used as gel-type strongly acidic cation exchange resins (mixed bed ratio: 25% by volume) to be mixed with the chelating resin. PGMEA before purification (raw solution) and PGMEA at the column outlet after purification were collected, and the acetic acid concentration and water concentration were measured. The results are shown in Table 3.

[0050] [Table 3]

[0051] As shown in Table 3, it was found that, among gel-type strongly acidic cation exchange resins, when a highly cross-linked resin was used, the generation of acetic acid was reliably suppressed.

[0052] [Reference Example 1: Reduction of acetic acid using anion exchange resin] PGMEA was purified in the same manner as in Example 3, except that only ORLITE (registered trademark) DS-6, an MR type weakly basic anion exchange resin, was used as the resin. PGMEA before purification (stock solution) and PGMEA at the column outlet after purification were collected, and the acetic acid concentration was measured. The results are shown in Table 4.

[0053] [Table 4]

[0054] As shown in Table 4, it was found that the acetic acid contained in the raw solution can be removed by using an anion exchange resin. Therefore, it was revealed that the hydrolyzable organic solvent can be purified while reliably suppressing the generation of acetic acid by using an anion exchange resin in combination with the cation exchange resin and any chelating resin according to the present invention.

Claims

1. A method for purifying a hydrolyzable organic solvent, comprising a purification step of purifying the hydrolyzable organic solvent by contacting the hydrolyzable organic solvent with a cation exchange resin mixed with a chelating resin, wherein the volume ratio of the cation exchange resin to the total amount of the cation exchange resin and the chelating resin is 10 to 50%, and the hydrolyzable organic solvent is an ester-based organic solvent or a mixed solvent containing an ester-based organic solvent.

2. 2. The method according to claim 1, wherein the water concentration in the hydrolyzable organic solvent before purification is 20 to 10,000 mg / L.

3. 3. The purification method according to claim 1, further comprising a pretreatment step of performing a pretreatment on the cation exchange resin and the chelating resin before the purification step to suppress water elution from the resin, the pretreatment being a method of contacting the cation exchange resin and the chelating resin with a pretreatment organic solvent having a higher relative dielectric constant at 25°C than that of the hydrolyzable organic solvent, or a method of reducing the water content of the cation exchange resin and the chelating resin to 10 mass% or less using a dryer.

4. The purification method according to any one of claims 1 to 3, wherein an anion exchange resin is further used in combination with the cation exchange resin and the chelating resin.

5. The purification method according to any one of claims 1 to 4, wherein the cation exchange resin is a strongly acidic cation exchange resin.

6. 6. The purification method according to claim 5, wherein the strongly acidic cation exchange resin is an MR type strongly acidic cation exchange resin.

7. The purification method according to claim 5, wherein the strongly acidic cation exchange resin is a gel-type strongly acidic cation exchange resin having a cross-linking degree of 16% to 24%.

8. The purification method according to any one of claims 1 to 7, wherein in the purification step, the concentration of each metal in the hydrolyzable organic solvent is reduced by 80 mass% or more.

9. The purification method according to any one of claims 1 to 8, further comprising a blowing step of discharging, after initiation of the purification step, the hydrolyzable organic solvent eluted from an outlet of a purification column packed with the cation exchange resin, the chelating resin and any anion exchange resin, outside a storage tank for storing the purified hydrolyzable organic solvent for a certain period of time.

10. A method for producing a resin for purifying a hydrolyzable organic solvent, comprising the step of mixing a chelating resin with a cation exchange resin, wherein a volume ratio of the cation exchange resin to a total amount of the cation exchange resin and the chelating resin is 10 to 50%, and the hydrolyzable organic solvent is an ester-based organic solvent or a mixed solvent containing an ester-based organic solvent.

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