JP5887279B2 - Method for producing tetraalkylammonium salt and method for producing tetraalkylammonium hydroxide using the same as raw material - Google Patents

Description

  The present invention relates to a novel method for producing a tetraalkylammonium salt using a cation exchange resin and a method for producing a tetraalkylammonium hydroxide using the same as a raw material.

Tetraalkylammonium hydroxide (hereinafter abbreviated as TAAH) is a useful compound as a standard solution for bases in non-aqueous solution titration and organic alkaline agents in organic synthesis, including phase transfer catalysts. In addition, it is used as a processing agent for cleaning a semiconductor substrate, etching, developing a photoresist, etc. in the manufacture of integrated circuits and large scale integrated circuits.
In particular, in semiconductor applications, high purity TAAH containing as little impurities as possible is required because the semiconductor substrate is contaminated.

  On the other hand, the waste liquid used for developing the photoresist as described above contains metal ions and TAAH in addition to the photoresist. In order to reduce the environmental load, TAAH is recovered from the waste liquid and reused. Technology has become important (hereinafter, waste liquid containing photoresist and TAAH may be referred to as “photoresist development waste liquid”). Conventionally, methods for treating photoresist developing waste liquid have mainly been concentrated by evaporation or reverse osmosis membrane method and disposed of (incinerated or collected by a contractor), and biodegraded by activated sludge and discharged. . However, as described above, many attempts have been proposed to recover TAAH from the waste liquid and reuse it for environmental consideration.

  Specifically, there is known a method for recovering TAAH by concentrating waste liquid or developing waste liquid that originally has a high TAAH concentration to neutralize it and remove the photoresist component, followed by electrodialysis or electrolysis. (For example, see Patent Documents 1 to 3). However, when processing waste liquid with a low TAAH concentration, it is necessary to concentrate the TAAH waste liquid to a concentration condition for electrodialysis or electrolysis, so electrodialysis or electrolysis is not performed for these methods. A method for recovering TAAH from a photoresist developing waste solution (see Patent Document 4) has been proposed. As a specific method, first, tetraalkylammonium ions (TAA ions) are adsorbed on the cation exchange resin by bringing the photoresist developing waste solution into contact with the cation exchange resin. Next, hydrochloric acid is passed through the cation exchange resin to collect the TAA salt, and perchloric acid is added to the resulting solution to obtain a tetraalkylammonium perchlorate (TAA perchlorate). Thereafter, TAA perchlorate is purified by crystallization, and then the obtained perchlorate is contacted with an anion exchange resin to recover TAAH.

  Further, a technique for producing TAAH by adsorbing TAA ions to an ion exchange resin, recovering a TAA salt from a dilute developing waste solution, and electrolyzing it is disclosed (Patent Documents 5 and 6). However, since the conditions for eluting the TAA salt from the ion exchange resin are not controlled, metal ions are mixed in the obtained TAA salt solution, and as a result, the metal ions are relatively contained in the TAAH solution after electrolysis. There was a problem of mixing in a high concentration.

Japanese Patent Laid-Open No. 04-228587 Japanese Patent Laid-Open No. 05-106074 Japanese Patent No. 3216998 JP 2004-66102 A Japanese Patent No. 2688809 Japanese translation of PCT publication No. 2002-509029

  According to the former method, TAA ions can be recovered with a high yield, but according to the study by the present inventors, it has been found that there is room for improvement in the following points. In the above method, when collecting TAA ions, the concentration of TAA ions is measured, and since recovery is performed until the concentration of TAA ions is as low as 2000 ppm, the TAA ions are adsorbed on the cation exchange resin. Most TAA ions can be recovered. However, at the time of recovery, the concentration of TAA ions decreases and at the same time, a large amount of hydrochloric acid used for recovery is mixed, and metal ions adsorbed on the resin are also mixed. Therefore, the obtained TAA salt has a large amount of impurities. There was a problem of being included.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive studies. As a result, the TAA salt obtained when the TAA ion is adsorbed by bringing the photoresist developing waste solution into contact with the cation exchange resin and then the hydrochloric acid is passed through the cation exchange resin to recover the TAA salt. It has been found that a solution having a low metal ion concentration can be obtained by stopping the recovery before the pH of the solution falls below a prescribed value and / or before the rate of change in electrical conductivity rises above a prescribed value. It came to be completed.

  That is, in the present invention, a solution containing metal ions and tetraalkylammonium hydroxide (TAAH) is passed through an adsorption tower packed with a cation exchange resin, and the tetraalkylammonium ions are adsorbed on the cation exchange resin. In the method for producing a tetraalkylammonium salt by passing an acid solution through the adsorption tower and collecting the recovered liquid flowing out from the adsorption tower, the pH and / or electric conductivity of the recovered liquid flowing out is adjusted. A method for producing a tetraalkylammonium (TAA) salt, characterized in that a recovery amount of a recovered liquid is determined by measurement.

  Furthermore, in the present invention, a TAAH solution having a high purity can be obtained by bringing the TAA salt thus obtained into contact with an anion exchange resin that has been previously made OH type or by performing electrolysis.

  The tetraalkylammonium hydroxide (TAAH) produced by the method of the present invention can be suitably used as a developer for producing a liquid crystal display.

  According to the method of the present invention, since the recovered amount of the TAA salt solution recovered by a simple method such as pH measurement and / or electrical conductivity measurement is determined, a highly pure TAA salt can be obtained efficiently. Therefore, it is not necessary to provide a metal removal step using a chelate resin or the like in the previous and subsequent steps, the configuration of the apparatus is simplified, and the cost is reduced.

  Furthermore, a TAAH solution with high purity can be obtained by bringing the TAA salt into contact with an anion exchange resin or by performing electrolysis.

It is a schematic diagram which shows one embodiment of the manufacturing equipment concerning the manufacturing method of the tetraalkylammonium salt of this invention. It is a graph regarding the Example of this invention. It is a graph regarding the Example of this invention. It is a graph regarding the Example of this invention. It is a graph regarding the Example of this invention.

The present invention relates to a method for producing a tetraalkylammonium salt (TAA salt) from a solution containing metal ions and a tetraalkylammonium hydroxide (TAAH), wherein the TAAH solution is contacted with a cation exchange resin, and TAA After the ions are adsorbed on the cation exchange resin, the acid solution is passed through the adsorption tower and the pH and / or electrical conductivity of the recovered liquid flowing out from the adsorption tower is measured to stop recovery of the recovered liquid. This is a method for determining the timing and obtaining the TAA salt.
(Solution containing metal ions and tetraalkylammonium hydroxide)
In the present invention, the solution containing metal ions and tetraalkylammonium hydroxide is not particularly limited as long as it contains these components (hereinafter also referred to as “raw material solution”). Since these components are contained and a large amount is generated in a semiconductor manufacturing process, a liquid crystal display manufacturing process, etc., a photoresist developing waste liquid discharged from the process is preferable. These waste liquids are waste liquids that are discharged when developing the exposed photoresist with an alkaline developer, and mainly contain photoresist, TAAH, and metal ions.

  Photoresist development waste liquid usually exhibits alkalinity with a pH of 10 to 14, and in the alkaline development waste liquid, acid groups such as carboxyl groups and phenolic hydroxyl groups are dissolved by acid dissociation. . Examples of the main photoresist include indenecarboxylic acid produced by photolysis of a photosensitizing agent o-diazonaphthoquinone and phenols derived from a novolac resin. In addition, in this invention, the thing containing the said photoresist component and what remove | eliminated a part or all of the said photoresist component previously can also be made into object.

  Here, typical waste liquid discharged from the development process in semiconductor manufacturing and liquid crystal display manufacturing will be described in detail. In the developing process, a single-wafer type automatic developing apparatus is usually used. In this apparatus, a process using a developer containing TAAH and a subsequent rinse (substrate cleaning) with pure water are performed in the same tank. In this case, in the rinsing step, 5 to 1000 times as much pure water as the developer is used. Therefore, the developer used in the development step is usually a waste solution diluted 5 to 10 times. As a result, the composition of the waste liquid discharged in this development step is such that TAAH is about 0.001 to 1% by mass, the resist is about 10 to 100 ppm, and the surfactant is about 0 to several tens ppm. Become. In addition, waste liquids from other processes may be mixed, and the TAAH concentration may be further lowered within the above range. Specifically, it may be 0.05 mass% or less (about 0.001-0.05 mass%). In particular, the photoresist developing waste liquid discharged from the liquid crystal display manufacturing process often has a TAAH concentration of 0.001 to 0.5% by mass, and the method of the present invention can be applied to such a photoresist developing waste liquid from the TAA salt. It can employ | adopt especially suitably for manufacturing.

  The photoresist development waste liquid contains a plurality of metal ions. For example, monovalent ions such as sodium and potassium, divalent ions such as calcium and zinc, and other polyvalent ions such as aluminum, nickel, copper, chromium and iron in the photoresist developing waste liquid. It is a metal that is typically contained in large quantities.

  TAAH in the photoresist developing waste liquid is an alkali used in a photoresist developing solution used in the production of various electronic components. Specific examples of TAAH include tetramethylammonium hydroxide (hereinafter abbreviated as TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, trimethylethylammonium hydroxide, water Dimethyldiethylammonium oxide, trimethyl (2-hydroxyethyl) ammonium hydroxide, triethyl (2-hydroxyethyl) ammonium hydroxide, dimethyldi (2-hydroxyethyl) ammonium hydroxide, diethyldi (2-hydroxyethyl) ammonium hydroxide, water Examples include methyl tri (2-hydroxyethyl) ammonium oxide, ethyl tri (2-hydroxyethyl) ammonium hydroxide, and tetra (2-hydroxyethyl) ammonium hydroxide. Rukoto can. Among these, TMAH is most widely used.

(Step of adsorbing tetraalkylammonium ions to cation exchange resin)
In the present invention, the raw material solution as described above is passed through an adsorption tower packed with a cation exchange resin of hydrogen ion type (hereinafter also referred to as “H type”) to adsorb TAA to the cation exchange resin. .

  That is, since TAA ions are cations, they are adsorbed on the resin by causing ion exchange with hydrogen ions of the cation exchange resin by contacting with the H-type cation exchange resin. Therefore, TAA ions can be efficiently recovered from the waste liquid. In particular, TAA ions can be recovered at a low cost even in a waste liquid when the concentration of TAAH is low.

  Here, since the normal metal ion is also a cation, it will be adsorbed by the cation exchange resin by this liquid flow. In the present invention, by adopting a method to be described later, metal ions and TAA ions that have been adsorbed on such a cation exchange resin are efficiently separated. Even metal ions are difficult to be adsorbed by cation exchange resins when the ion species containing the metal itself is an anion due to a chemical equilibrium reaction such as complex formation in the raw material solution. Discharged from the tower.

  On the other hand, when the raw material solution is a photoresist waste solution, since the dissolved organic component derived from the photoresist is usually in the form of an anion, it is hardly adsorbed by the cation exchange resin and is largely removed. Even when nonionic components are present, most of the components can be removed because they are discharged (outflow) without being adsorbed by the cation exchange resin in this step. After that, the resist remaining slightly on the cation exchange resin may be washed by flowing it with ultrapure water or a highly pure TAAH solution.

(Cation exchange resin)
In the present invention, the cation exchange resin is not particularly limited, and known ones can be used. Specifically, either a strongly acidic cation exchange resin whose ion exchange group is a sulfonic acid group or a weakly acidic cation exchange resin whose ion exchange group is a carboxyl group can be used. Among them, it is preferable to use a weakly acidic cation exchange resin because many of them have a large ion exchange capacity and can reduce the amount of resin used. Further, in the case of a weakly acidic cation exchange resin, elution of TAA ions described later is easy.

  The resin structure may be a gel type or an MR type (macroporous type). The shape of the resin may be any of powder, granule, film, fiber and the like. In view of processing efficiency, operability, economy and the like, it is preferable to use granular styrene-based or acrylic-based cation exchange resins.

  The counter ion of the cation exchange resin is usually marketed as a hydrogen ion (H type) or sodium ion (Na type), but it prevents the final mixing of the TAAH solution with sodium ions, and TAA In order to improve the adsorption efficiency of ions, the H type in which counter ions are hydrogen ions is preferable. When using a cation exchange resin that is commercially available in Na type, pre-flow an acid such as hydrochloric acid or sulfuric acid through the cation exchange resin and thoroughly wash with ultrapure water before use. Are used as hydrogen ions.

  Specific examples of strongly acidic cation exchange resins include Amberlite IR120B and Amberlite IR124 manufactured by Rohm and Haas, Diaion SK1B and Diaion PK228 manufactured by Mitsubishi Chemical, Duolite C255LFH manufactured by Sumika Chemtex, and LANXESS Examples include Lebatit Monoplus S100, Purolite Purolite C160, and the like. Specific examples of the weakly acidic cation exchange resin include Amberlite IRC76 manufactured by Rohm and Haas, Diaion WK40L manufactured by Mitsubishi Chemical, Duolite C433LF and Duolite C476 manufactured by Sumika Chemtex, and Lexit CNP80WS manufactured by LANXESS. And Purolite Purolite C104.

(Method of passing the solution through an adsorption tower packed with cation exchange resin)
In the present invention, the TAA ions are adsorbed on the cation exchange resin by passing the raw material solution through the adsorption tower packed with the H-type cation exchange resin and bringing it into contact with the cation exchange resin.

  In addition, as a method for passing the raw material solution through an adsorption tower filled with a cation exchange resin, a conventionally known method can be appropriately employed depending on the type and shape of the cation exchange resin. Specifically, for example, a cylindrical adsorption tower having an inflow hole in the upper part and an outflow hole in the lower end part is used. The adsorption tower is filled with a cation exchange resin, and the raw material solution is continuously applied using gravity. The method of letting it pass is preferable. When this method is adopted, the size of the adsorption tower may be appropriately determined according to the performance of the cation exchange resin. In order to efficiently adsorb TAA ions, if the photoresist waste liquid has a TAAH content of 0.001 to 1% by mass, the ratio of the height (L) to the diameter (D) of the adsorption tower (L / D) is preferably 0.5 to 30, and the space velocity (SV) of the waste liquid is preferably 1 (1 / hour) to 150 (1 / hour).

  In addition, it is preferable that the amount of the raw material liquid to be passed is an amount that does not allow the cation exchange resin packed in the adsorption tower to break through, so that the TAA salt can be produced efficiently.

  Note that whether or not TAA ions flow out (breakthrough) without being adsorbed by passing a raw material solution containing an amount of cation more than the exchange capacity of the cation exchange resin. This can be confirmed by analyzing the TAA ion concentration in the liquid flowing out through the ion chromatography method. More simply, the height occupied by the cation exchange resin in the adsorption tower may be measured. When the counter ion of the cation exchange resin is changed from a hydrogen ion to a TAA ion, the volume swells to about 2 times depending on the kind of the cation exchange resin. Therefore, the adsorption of TAA ions can be confirmed by measuring the volume of the cation exchange resin.

  In addition, when the pH of the raw material solution is 10 or more, if the TAA ions pass through the adsorption tower without being adsorbed, the pH of the liquid that has passed through becomes alkaline, so it can also be confirmed by a pH meter. . In general, when TAA ions are contained in the liquid that has flowed out through the adsorption tower, the electric conductivity of the liquid is increased, so that it can also be confirmed by the electric conductivity.

(Step of recovering tetraalkylammonium salt from cation exchange resin adsorbed with tetraalkylammonium ion)
In the present invention, after the TAA ions are adsorbed on the cation exchange resin by the above method, the acid solution is passed through the adsorption tower filled with the cation exchange resin, and the recovered liquid flowing out from the adsorption tower is recovered. To produce a tetraalkylammonium salt.

  That is, by introducing the acid solution from one end of the adsorption tower to the adsorption tower and allowing the liquid to flow out from the other end, a large excess of hydrogen ions contained in the acid solution are sequentially replaced with TAA ions. The TAA ions flow out from the adsorption tower as acid acid salts used.

  The acid solution is preferably an aqueous solution in consideration of cost and the like.

  Specific examples of the acid that can be used include hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, acetic acid, and the like, but strong acid such as hydrochloric acid, sulfuric acid, Nitric acid is preferred. Among these, hydrochloric acid is most preferable in that it is easy to remove excess acid by concentration under reduced pressure, and has a low oxidizing power and is not easily damaged.

  The concentration of the acid solution can be appropriately selected in the range of 0.1N to 10N, but the range of 0.5N to 4N is easy in that the high-concentration TAA salt flows out and metal impurities are easily prevented from being mixed. Particularly preferred.

  Further, the flow rate of the acid solution can be appropriately set according to the size of the adsorption tower, the type and amount of the cation exchange resin, the concentration of the acid solution, etc., but preferably the acid space velocity is 1 or more and 50. It is as follows. If it is smaller than this, processing takes time.

(Recovery of effluent)
By passing the acid solution described above, TAA ions flow out (elute) from one end of the adsorption tower as a TAA salt using an acid radical (for example, Cl 2 ⁻ ) corresponding to the acid used as a counter ion. Is recovered in a storage tank, and the recovered liquid is subjected to electrolysis described later.

  The feature of the present invention is that the pH and / or electrical conductivity of the effluent is measured, and the recovery to the storage tank is stopped when a predetermined measurement value is reached.

  That is, the cation exchange resin in the adsorption tower adsorbs metal ions in addition to TAA ions as described above, but the time point when the pH of the effluent reaches a predetermined value and / or the electrical conductivity is specified. By stopping recovery before the width changes, the amount of mixed metal ions can be kept low.

  In addition, at the time after the time when the pH and / or electric conductivity of the effluent becomes the predetermined value, the effluent from the adsorption tower may be stopped, but the flow path such as a switching valve may be changed. It is preferable that a means is provided, and when the predetermined value is reached, it is recovered to a storage tank or the like different from the storage tank.

  A known means for measuring pH and / or electrical conductivity can be used without particular limitation.

(Predetermined pH value and its measurement method)
The predetermined pH value varies depending on the type of acid used. For example, when hydrochloric acid, which is a strong acid, is used as the acid, TAA chloride (hereinafter referred to as “TAAC”), which is an outflowing salt, is neutral, so that outflow occurs in a state where TAA ions are sufficiently present in the adsorption tower. The liquid is almost neutral (in the case of a strong acid cation exchange resin) or weakly basic to neutral (in the case of a weak acid cation exchange resin), but gradually begins to exhibit acidity as TAA ions decrease.

  In the equilibrium state, even if the effluent is weakly acidic, TAA ions (TAAC) are contained in the effluent, but it gradually decreases. On the other hand, as the acid flowing through the adsorption tower becomes more acidic. The elution amount of metal ions that are strongly adsorbed on the cation exchange resin gradually increases.

  Therefore, if the acid solution is kept flowing, TAA ions are hardly contained in the effluent, but metal ions are contained in a large amount. Therefore, when the recovery rate of TAA is emphasized, the predetermined pH value is set low, and when the reduction of the mixed amount of metal ions is emphasized, it is set high.

  When a strong acid such as hydrochloric acid is used as the acid, the pH of the recovered liquid flowing out from the adsorption tower is measured, and the recovery is stopped when the pH reaches a predetermined value in the range of 3 to 8. A liquid having a low concentration of metal ions contained in the prepared TAA salt solution can be obtained. In order to further lower the metal ion concentration, the predetermined value is preferably set to pH 5 or more. Moreover, it is possible to collect the TAA salt at a high recovery rate by setting the predetermined value to a pH of 7 or less. The strong acid means an acid dissociation constant pKa at 25 ° C. of 3 or less.

  On the other hand, when the acid to be used is a weak acid such as acetic acid or carbonic acid, the resulting TAA salt solution exhibits weak alkalinity, and therefore the preferable pH range for reducing the amount of metal ion contamination is 4-9. The weak acid means an acid dissociation constant pKa at 25 ° C. higher than 3.

  As a method for measuring pH, a conventionally known method can be appropriately employed. Specifically, for example, a certain amount of the effluent flowing out from the adsorption tower is sampled and the pH is measured using a pH test paper or an electrode-type pH meter, or in-line in the middle of the piping that leads the effluent to storage or the like. There is a method of measuring by installing a type pH meter. If an in-line type pH meter is used, the recovery can be stopped at the moment when the pH is out of the specified value without taking out the liquid halfway, and the loss of the recovered liquid can be suppressed, which is preferable.

  Although it depends on the pH measurement means, measuring the pH of the fluid in-line using a general glass electrode type pH meter, due to its characteristics and non-uniformity of the resin packed state in the adsorption tower, etc. Depending on the factor, blurring often occurs at about ± 0.2. In the present invention, in such a case, the pH value indicated by the pH meter is statistically processed, and recovery of the effluent into the storage tank may be stopped when the statistical value reaches a predetermined value.

  As the statistical processing method, a known processing method may be adopted as appropriate. For example, a value is obtained every predetermined time (for example, 0.1 seconds), and an arithmetic average of the predetermined time (for example, 2 seconds) is obtained. Alternatively, if the geometric average value is a predetermined value, a predetermined pH value may be used. Some commercially available pH meters are equipped with such statistical processing means and have a function of displaying the pH after statistical processing. In the present invention, such a pH meter can be used as it is.

  In addition, it is necessary to change the time interval which performs a statistical process mainly with the flow volume (flow velocity) of an effluent. When the solution is flowed at a high flow rate, the pH of the effluent changes rapidly, so that it is necessary to shorten the measurement interval in order to obtain a liquid having a desired property (metal ion concentration).

(Change rate of electrical conductivity and its measurement method)
The rate of change in electrical conductivity varies depending on the type of acid used as well as pH, and also varies depending on the concentration of acid flowing through the adsorption tower. That is, the TAA salt concentration contained in the effluent from the adsorption tower is high when the acid concentration is high, and thin when it is thin. When sufficient TAA ions are present in the adsorption tower, the concentration state is maintained (if the outflow rate is kept constant) and the outflow is performed (hereinafter also referred to as “concentration maintenance state”).

  If the TAA ions are sufficiently eluted from the cation exchange resin while the acid solution continues to flow through the adsorption tower, the TAA salt concentration contained in the effluent gradually decreases and the free acid and metal salt concentrations increase. At this time, since the electrical conductivity of the TAA salt solution is usually different from that of the free acid and metal salt solution, the timing at which the free acid and metal salt start to be mixed is detected by measuring the electrical conductivity. It becomes possible.

  Specifically, when tetramethylammonium (TMA) ions are used as TAA ions, 2N hydrochloric acid is used as the acid, and the flow rate (SV) is 1, the liquid flowing out from the column is tetramethylammonium chloride containing no hydrochloric acid. In the case of (TMAC), it is about 80 mS / cm, and rises up to about 500 mS / cm (2N hydrochloric acid) with mixing of hydrochloric acid.

  In addition, since the electric conductivity in the state of maintaining the concentration changes depending on the type and concentration of the acid, the type of cation exchange resin, the shape of the column, the flow rate, etc., it is necessary to check the operating conditions of the apparatus. .

  Taking into account variations in measured values of electrical conductivity due to measurement accuracy (less than ± 1% of full scale) of commonly used electrical conductivity meters, column shape, non-uniformity of ion exchange resin packing, etc. The fluctuation range of the electrical conductivity in the state where the concentration is maintained is less than ± 5%. Therefore, when an increase in conductivity exceeding this fluctuation range is observed, it can be determined that hydrochloric acid has started to be mixed into the flowing liquid.

  In the present invention, in such a case, the electrical conductivity indicated by the electrical conductivity meter is statistically processed, and when the statistical value becomes 5% or more larger than the electrical conductivity in the concentration maintaining state, What is necessary is just to stop collection | recovery to the storage tank of a liquid.

  As the statistical processing method, a known processing method may be adopted as appropriate. For example, a value is obtained every predetermined time (for example, 0.1 seconds), and an arithmetic average of the predetermined time (for example, 2 seconds) is obtained. Alternatively, the geometric average value may be used as electric conductivity. Some commercially available electric conductivity meters are equipped with such statistical processing means and have a function of displaying the electric conductivity after statistical processing. In the present invention, such an electric conductivity meter is used as it is. Is also possible.

  In addition, it is necessary to change the time interval which performs a statistical process mainly with the flow volume (flow velocity) of an effluent. When the solution is flowed at a high flow rate, the electrical conductivity of the effluent changes rapidly, so that it is necessary to shorten the measurement interval in order to obtain a liquid having a desired property (metal ion concentration).

(Method for producing tetraalkylammonium hydroxide from tetraalkylammonium salt)
In the present invention, TAAH can be produced by subjecting the TAA salt contained in the solution recovered from the waste liquid to electrolysis or contact with an anion exchange resin having hydroxide ions as a counter ion by the above method. .

(Production of TAAH: TAA salt electrolysis process)
The electrolysis step of electrolyzing the obtained TAA salt to make TAAH is not particularly limited, and a known method can be used. Among them, the anode, cathode, and cation exchange described in Japanese Patent No. 2059769 It is preferable to produce by electrolysis using a membrane.

(Production of TAAH: contact process between TAA salt and anion exchange resin)
As a method for producing TAAH by bringing a TAA salt contained in a solution recovered from a waste solution into contact with an anion exchange resin, methods described in JP-A-52-003009 and Japanese Patent Application No. 2009-197778 are employed. The This method is a method for producing TAAH from TAAC by contacting an anion exchange resin (OH type anion exchange resin) having a hydroxide ion as a counter ion with a TAA salt. In this method, high-purity TAAH can be easily produced from TAAC without electrodialysis or electrolysis.

  As described above, according to the present invention, a highly pure TAA salt can be obtained. Further, compared to the conventional method, a metal ion removing step such as a chelate resin is not necessary, so that the total cost for processing can be reduced. Further, when the TAA salt is recovered from the photoresist developing waste liquid, the amount of metal impurities can be reduced to 1/10 or less of the original amount. Further, when TAAH is produced by the above method using this, the obtained TAAH can be suitably used as a developer for a liquid crystal display.

  In order to describe the present invention more specifically, examples and comparative examples will be described below, but the present invention is not limited to these examples.

(Regeneration treatment of cation exchange resin (H-type cation exchange resin))
In use, the used cation exchange resin was filled in a glass tower, and ultrapure water, 1N-HCl (hydrochloric acid), and ultrapure water were passed in this order to make the counter ion a hydrogen ion. Each liquid was passed at a space velocity of SV 5 (l / hour), and the amount of liquid used was 10 L / L-resin.

(Concentration measurement)
Tetramethylammonium hydroxide (TMAH), tetramethylammonium chloride (TMAC) concentration, and chloride ions were analyzed by ion chromatography.

  Specifically, ICS2000 manufactured by Dionex Corporation is used, the column is ION-pac CS12A for cation analysis, ION-pac AS15 is used for anion analysis, and the eluent is methanesulfonic acid for cation analysis. Anion analysis was performed using potassium hydroxide.

  The metal ion concentration contained in the solution was determined by the high frequency inductively coupled plasma mass spectrometry (ICP-MS) method (measuring device: HP-4500 (manufactured by Agilent)) and the high frequency inductively coupled plasma emission analysis (ICP-OES) method ( Measuring apparatus: Measured with iCAP 6500 DUO (manufactured by Thermo Electron Ltd.).

  The pH of the solution was measured by a pH electrode method (measuring device: HM-30R, manufactured by Toa DKK Corporation). The electrical conductivity was measured using an SC meter (model number: SC72-21JAA) manufactured by Yokogawa Electric.

Example 1
100 ml of weakly acidic cation exchange resin Diaion WK40L (manufactured by Mitsubishi Chemical Corporation) was packed in a glass column having a diameter of 22 mm × 750 mm, and the above regeneration treatment was performed.

(TAA ion adsorption process)
In this column, 8000 ml of 0.5 mass% TMAH waste solution (photoresist development waste solution, photoresist content, COD conversion 42 ppm, metal ion concentration Na: 9.0 ppb, Al: 4.4 ppb, K: 1.1 ppb, Ca: 12.2. 9 ppb, Cr: 5.5 ppb, Fe: 16.4 ppb, Ni: 1.2 ppb, Cu: 0.14 ppb) were passed at a space velocity SV = 20 (l / hour).

(Washing process)
Next, 100 ml of 0.5 mass% TMAH was passed at a space velocity SV = 1 (l / hour) to wash the resist.

(Contact process with hydrochloric acid / TAAC recovery process)
Next, 800 ml of 1N-HCl was passed as an eluent at a space velocity SV = 1 (l / hour), and the adsorbed TMA ions were eluted as TMAC. The eluate was sequentially collected and fractionated into the following 12 liquids. From 0 to 500 ml, 5 by 100 ml (separation liquids A to E), from 500 to 600 ml, 5 ml by 20 ml (fractionation liquids F-1 to 5), and from 600 to 800 ml, 2 by 100 ml each (fractionation liquid G, H). These fractions were measured for TMAC concentration by ion chromatography, metal ion concentration by ICP mass spectrometry, and pH by a pH meter. The results are shown in Table 1, FIG. 2 and FIG.

  As is clear from the results in Table 1, the metal ion concentration increased from F-3 where the pH was 7 or less. The metal ion concentration of the combined solution from fractions B to F-2 was 10 ppb or less for all metals, the TMAC concentration was 7.8% by mass (0.71 mol / l), and HCl was not contained. The TMAC recovery rate at this time was 90.0%.

Example 2
TMAC was obtained in the same manner as in Example 1 except that 2N hydrochloric acid was used as the acid used for elution and the operation of the contact step with hydrochloric acid was performed under the following conditions. The results are shown in Table 2.

(Contact process with hydrochloric acid / TAAC recovery process)
Next, 600 ml of 2N-HCl was passed as an eluent at a space velocity SV = 1 (l / hour), and the adsorbed TMA ions were eluted as TMAC. The eluate was sequentially collected and fractionated into the following 12 liquids. From 0 to 400 ml, 80 ml each (5 fractions A to E), from 400 to 500 ml 5 ml each (separation fluids F-1 to 5), from 500 to 600 ml two 50 ml each (separation fluid G, H). These fractions were measured for TMAC concentration by ion chromatography, metal ion concentration by ICP mass spectrometry, and pH by a pH meter. The results are shown in Table 2.

  From Table 2, it can be seen that the metal ion concentration increases when the pH is 7 or less.

Example 3
TMAC was obtained in the same manner as in Example 1 except that 4N hydrochloric acid was used as the acid used for elution and the operation of the contact step with hydrochloric acid was performed under the following conditions. The results are shown in Table 3.

(Contact process with hydrochloric acid / TAAC recovery process)
Next, 600 ml of 4N-HCl was passed as an eluent at a space velocity SV = 1 (l / hour), and the adsorbed TMA ions were eluted as TMAC. The eluate was sequentially collected and fractionated into the following 12 liquids. From 0 to 250 ml, 5 by 50 ml (separation liquids A to E), from 250 to 500 ml, 5 by 50 ml each (fractionation liquids F-1 to 5), from 500 to 600 ml, 2 by 50 ml each (fractionation liquid G, H). These fractions were measured for TMAC concentration by ion chromatography, metal ion concentration by ICP mass spectrometry, and pH by a pH meter. The results are shown in Table 3.

  From Table 3, it can be seen that when the pH is 7 or less, the metal ion concentration increases.

Example 4
The TMAC obtained by the method of Example 1 was evaporated and concentrated to prepare a 27.5% by mass TMAC solution. The obtained concentrated TMAC solution was subjected to the following electrolysis step to produce TAAH.

In the electrolysis step, a three-chamber type electrolytic cell in which one anion exchange membrane and one cation exchange membrane (both Nafion 90209 (manufactured by DuPont)) were arranged in order from the anode was used. The effective membrane area of the ion exchange membrane was ² dm ² , and the Nafion membrane was placed with the surface having a carboxylic acid group facing the cathode side. The anode was a titanium plate plated with platinum, and the cathode was SUS316. 0.5N sulfuric acid was circulated in the anode chamber of the electrolytic cell, the TMA chloride solution was circulated between the anion exchange membrane and the cation exchange membrane on the cathode side, and pure water was circulated in the cathode chamber to obtain a current density of 18A. Electrolysis was continuously performed while maintaining the temperature at 40 ° C./dm ² . During continuous operation, the concentration of tetramethylammonium hydroxide in the cathode chamber was set to 18% by mass. Similarly, pure water was added when the concentration increased, and the components were added when the concentration decreased, so that the concentration of the liquid circulating in each chamber became constant.

  Table 4 shows the analysis results of the TAAH solution obtained after the start of electrolysis, after 12 hours (at the time of stabilization) when the operation state is stable, and at the time of continuous operation for 3 months.

Example 5
TMAH was manufactured by electrolyzing TMAC obtained by the method of Example 2 by the method similar to Example 4. FIG. The results are shown in Table 4.

Example 6
(Regeneration treatment of cation exchange resin (H-type cation exchange resin))
A cation exchange resin (1000 ml) is packed into a vinyl chloride column with a diameter of 50 mm × 2000 mm, and the space velocity SV when passing ultrapure water, 1N-HCl (hydrochloric acid), etc. is 4 (l / hour). A regeneration treatment was performed in the same manner as in Example 1 except that the amount of liquid used was changed to 5 L / L-resin.

(TAA ion adsorption process)
80 l of 0.5% by mass TMAH waste liquid having the same composition as in Example 1 was passed through the column at a space velocity of SV = 20 (l / hour).

(Washing process)
Next, 2 l of 0.5 mass% TMAH was passed at a space velocity SV = 5 (l / hour) to wash the resist.

(Contact process with hydrochloric acid / TAAC recovery process)
Next, 8000 ml of 1N-HCl was passed as an eluent at a space velocity of SV = 5 (l / hour), and the adsorbed TMA ions were eluted as TMAC. The eluate was fractionated sequentially and separated into the following 23 liquids. First, 0 to 1000 ml is fractionated (Fractionation liquid A), from 1000 to 5000 ml, 8 by 500 ml (fractionation liquids BI), and from 5000 to 6000 ml, 10 by 100 ml (fractionation liquids J-1 to J-10). ), From 6000 to 8000 ml, was divided into a total of 23 pieces of 4 (separated liquids K to N) of 500 ml each. These fractions were measured for TMAC concentration by ion chromatography, metal ion concentration by ICP mass spectrometry, and pH by a pH meter. The results are shown in Table 5, FIG. 4 and FIG. Table 6 shows the pH, electrical conductivity, TMAC concentration, and metal ion concentration of the combined liquids of the fractionated liquids B to J-5.

  As is clear from the results in Table 5, the metal ion concentration increased from J-6 where the pH was 7 or less. Moreover, from the result of Table 6, the metal ion density | concentration of the total liquid of fractionation liquid B to J-5 is 3.5 ppb or less in any metal, and TMAC density | concentration is 7.7 mass% (0.71 mol / l). It was confirmed that HCl was not contained. The TMAC recovery rate at this time was 87.8%.

Claims (2)

A method for producing a tetraalkylammonium salt solution, wherein a solution containing a tetraalkylammonium salt is obtained from a solution containing a metal ion and a tetraalkylammonium hydroxide,
(1) A solution containing metal ions and tetraalkylammonium hydroxide is passed through an adsorption tower packed with a hydrogen ion type cation exchange resin, and the tetraalkylammonium ions in the solution are subjected to cation exchange. Adsorption process to adsorb to the resin,
(2) In the adsorption step, an acid solution is passed through an adsorption tower packed with a cation exchange resin adsorbed with tetraalkylammonium ions, and the tetraalkylammonium ions adsorbed on the resin are converted into the acid. A recovery step of eluting as a salt and recovering the effluent flowing out of the adsorption tower in a storage tank;
In the recovery step, the pH of the effluent from the adsorption tower is measured, and when the pH of the effluent becomes 5 to 8 , the effluent to the storage tank A method for producing a tetraalkylammonium salt solution, wherein the recovery is stopped. A method for producing tetraalkylammonium hydroxide, comprising producing a tetraalkylammonium salt by using the obtained tetraalkylammonium salt as a raw material after producing a tetraalkylammonium salt by the method according to claim 1 .

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