TWI549753B - Tetraalkylammonium salt solution - Google Patents

Description

Method for producing tetraalkylammonium salt solution

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

Tetraalkylammonium hydroxide (hereinafter abbreviated as TAAH) is generally an effective compound as a labeling solution for a base in a nonaqueous solution titration or an organic alkalizing agent in an organic synthesis, mainly including an interphase transfer catalyst. Further, it is used as a treatment agent for cleaning, etching, or photoresist development of a semiconductor substrate in the production of an integrated circuit or a large-scale integrated circuit. In particular, in the use of semiconductors, since the semiconductor substrate is contaminated, high-purity TAAH which does not contain impurities as much as possible is required.

On the other hand, the waste liquid used in the above-mentioned photoresist development includes metal ion impurities and TAAH in addition to the photoresist, and the technology for recovering and reusing TAAH from the waste liquid becomes important because environmental load is to be reduced. (The following waste liquid containing photoresist and TAAH is also called "photoresist developing waste liquid"). Conventionally, a method for treating a photoresist development waste liquid is a method in which it is concentrated by an evaporation method or a reverse osmosis membrane method, and is disposed of (incinerated or removed by a manufacturer), and discharged by a biological decomposition treatment of activated sludge. Mainstream. However, as described above, from the viewpoint of environmental concerns, attempts have been made to recover and reuse TAAH from the waste liquid.

Specifically, it is known for concentrated waste liquid or original TAAH A method in which the developing waste liquid having a high concentration is subjected to neutralization treatment to remove the photoresist component, and then subjected to electrodialysis or electrolysis to recover TAAH (for example, refer to Patent Documents 1 to 3). However, when treating a waste liquid having a low TAAH concentration, it is necessary to concentrate the TAAH waste liquid in order to achieve the concentration conditions required for electrodialysis or electrolysis. Therefore, it is proposed that these methods are not subjected to electrodialysis or electrolysis from the photoresist development waste liquid. A method of recovering TAAH (refer to Patent Document 4). Specifically, the photoresist developing waste liquid is first contacted with the cation exchange resin to adsorb tetraalkylammonium ions (TAA ions) to the cation exchange resin. Thereafter, hydrochloric acid was introduced into the cation exchange resin to recover a TAA salt, and perchloric acid was added to the resulting solution to form a tetraalkylammonium perchlorate (TAA perchlorate). Thereafter, after the TAA perchlorate is crystallized and purified, the obtained perchlorate is brought into contact with an anion exchange resin to recover TAAH. However, the steps in this case become complicated, and the use of perchlorate which is in danger of explosion is difficult to manufacture in the industry.

Further, a TAA ion-adsorbing ion exchange resin, a technique of recovering TAA salt from a thin developing waste liquid, and electrolyzing it to produce TAAH has been disclosed (Patent Documents 5 and 6). However, since the conditions for dissolving the TAA salt from the ion exchange resin cannot be controlled, the obtained TAA salt solution is mixed with metal ion impurities, and as a result, a high concentration of metal ion impurities is mixed in the TAAH solution after electrolysis. Further, Patent Document 5 discloses a technique in which a weak acid is used in the case of dissolving from an ion exchange resin, but the eluted TAA salt solution tends to be thin, and particularly when carbonic acid is used, this tendency is remarkable. In the case of using carbonic acid, bubbles may occur in the liquid, which may cause an obstacle to continuous operation.

Further, Patent Document 7 discloses a technique for producing TAAH using a metal hydroxide when an ion exchange resin that adsorbs TAA ions dissolves TAA ions. However, this method has an organic substance such as a resist contained in the developing waste liquid. The problem in TAAH.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Publication No. 04-228587

Patent Document 2: Japanese Patent Publication No. 05-106074

Patent Document 3: Patent No. 3216998

Patent Document 4: JP-A-2004-66102

Patent Document 5: Patent No. 2688009

Patent Document 6: Japanese Patent Publication No. 2002-509029

Patent Document 7: Japanese Patent Publication No. 2004-512315

As described above, TAA ions can be recovered from the developing waste liquid in a high yield by using the cation exchange resin, but in this method, the removal of the resist component is insufficient, and only a problem of a rare TAA salt solution in which metal ion impurities are mixed can be obtained.

The present inventors reviewed the above problems in order to solve the above problems. As a result, it was found that TAA ions were adsorbed to the cation exchange resin by contact of the photoresist developing waste liquid with the cation exchange resin, and then a salt solution was introduced into the cation exchange resin to recover the TAA salt, and the obtained TAA salt solution was obtained. The metal ion concentration in the medium is stopped before the specific concentration is reached, and the TAA salt having a low metal ion impurity concentration can be obtained. This is electrolytically treated to effectively decompose and remove the resist component, thereby producing TAAH containing no resist component, to completion. this invention.

That is, the present invention is a method for producing a tetraalkylammonium salt solution containing a solution of a tetraalkylammonium salt having a reduced metal ion content ratio from a solution containing a metal ion and a tetraalkylammonium hydroxide, characterized in that it comprises The following steps (1) and (2) are formed: (1) in a adsorption tower filled with a hydrogen ion type cation exchange resin, a solution containing a metal ion and a tetraalkylammonium hydroxide is introduced to make a solution in the solution The adsorption step of adsorbing the alkylammonium ion on the cation exchange resin; (2) in the adsorption step, filling the adsorption tower of the cation exchange resin adsorbing the tetraalkylammonium ion, and introducing a solution of the alkali metal salt to adsorb the resin a tetraalkylammonium ion is formed by dissolving the salt described above, and recovering the effluent from the adsorption tower to a recovery step of the storage tank; and in the recovering step, measuring the concentration of the alkali metal ion in the effluent flowing out of the adsorption tower, A method for producing a tetraalkylammonium salt solution for recovering the effluent of the storage tank before the alkali metal ion concentration is rapidly increased.

Another invention includes the steps of (1) the adsorption step and (2) the recovery step, and in the recovery step, measuring the alkali metal ion concentration in the effluent of the adsorption tower, and setting the alkali metal ion concentration A method for producing a tetraalkylammonium salt solution for recovering the effluent of the storage tank at a specific concentration of between 0.5 and 10 mg/L.

Further, according to the present invention, the thus obtained TAA salt is subjected to electrolysis to obtain a TAAH solution having a high purity.

According to the method of the present invention, the amount of metal ions in the recovered TAA salt solution can be reduced, so that metal ion impurities can be efficiently obtained from the photoresist waste liquid. Low quality TAA salt. Therefore, it is possible to reduce the load of the metal removal step by the chelating resin or the like before and/or after the step, thereby reducing the cost.

Further, by performing electrolysis of the TAA salt, a highly pure TAAH solution containing no metal component and a resist component can be obtained.

Fig. 1 is a schematic view showing an embodiment of a manufacturing apparatus relating to a method for producing a tetraalkylammonium salt of the present invention.

Fig. 2 is a flow chart showing a preferred aspect of the recovery of a tetraalkylammonium salt (TAA salt) from a photoresist developing waste liquid and the production of tetraalkylammonium hydroxide (TAAH) from the TAA salt.

The present invention is a method for producing a tetraalkylammonium salt (TAA salt) solution having a reduced metal ion content ratio from a solution containing a metal ion and a tetraalkylammonium hydroxide (TAAH), and contacting the TAAH solution with a cation exchange resin. After the TAA ions were adsorbed to the cation exchange resin, a salt solution was passed through the adsorption column, and the concentration of metal ions in the recovered liquid flowing out of the adsorption tower was measured, and the time at which the recovery of the recovered liquid was stopped was determined to obtain a TAA salt. The "reduced metal element content ratio" indicates a decrease in the relative amount of TAA ions.

(solution containing metal ion impurities and tetraalkylammonium hydroxide)

In the present invention, the solution containing a metal ion and a tetraalkylammonium hydroxide is not particularly limited, but is preferably a photoresist development waste liquid which is produced in a semiconductor manufacturing process, a liquid crystal display manufacturing process, or the like. These waste liquids are the waste liquid discharged when the exposed photoresist is developed with an alkaline developing solution, mainly containing a photoresist, TAAH. And metal ions. These waste liquids are usually aqueous solutions.

The photoresist developing waste liquid usually exhibits an alkalinity of pH 10 to 14, and the photoresist in the alkaline developing waste liquid is decomposed and dissolved by an acid group such as a carboxyl group or a phenolic hydroxyl group. The main photoresist, such as the sensitizer o-diazonaphthoquinone, is formed by photodegradation of indene carboxylic acid or phenol from novolac resin.

Here, a representative waste liquid discharged from a developing step in semiconductor manufacturing and liquid crystal display manufacturing will be described in detail. The development step usually uses an automatic developing device of a single wafer process, in which the step of using a developer containing TAAH and then the step of moistening with pure water (substrate cleaning) are performed in the same tank, at this time in the wetting step. Use 5 to 10 times the amount of pure water of the developer. Therefore, the developer used in the development step is usually a waste liquid which is diluted 5 to 10 times. As a result, the composition of the waste liquid discharged in this developing step has a TAAH of about 0.001 to 1% by mass, a resist of about 10 to 100 ppm, and a surfactant of from zero to about several tens of ppm. There are also cases where waste liquid is mixed in other steps, and the TAAH concentration also becomes lower than the above range. Specifically, it may be 0.05% by mass or less (about 0.001 to 0.05% by mass). In particular, in the case of the photoresist development waste liquid discharged from the liquid crystal display manufacturing step, the TAAH concentration is often 0.001 to 0.5% by mass, and the method of the present invention is particularly suitable for the production of TAA salt from such photoresist development waste liquid.

The photoresist developing waste liquid contains a plurality of metal ions. For example, monovalent ions are sodium, potassium, etc., divalent ions are calcium, zinc, etc., and other multivalent ions are aluminum, nickel copper, chromium, iron, etc., which are representatively rich metals in photoresist development waste liquid. These metals usually contain about 0.1 to 100 ppb in the photoresist development waste liquid.

TAAH in photoresist development waste liquid is used for various electronic components. A base used in a photoresist developing solution for isochronous production. Specific examples of TAAH may, for example, tetramethylammonium hydroxide (hereinafter abbreviated as TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, and hydroxide. Trimethylethylammonium, dimethyldiethylammonium hydroxide, trimethyl(2-hydroxyethyl)ammonium hydroxide, triethyl(2-hydroxyethyl)ammonium hydroxide, dimethyl hydroxide Bis(2-hydroxyethyl)ammonium, diethylbis(2-hydroxyethyl)ammonium hydroxide, methyltris(2-hydroxyethyl)ammonium hydroxide, ethyltris(2-hydroxyethyl) hydroxide Ammonium, tetrakis(2-hydroxyethyl)ammonium hydroxide, and the like. Among these, TMAH is the most widely used.

(Step of adsorbing tetraalkylammonium ions to a cation exchange resin)

In the present invention, a solution containing a metal ion and a tetraalkylammonium hydroxide as described above is introduced into an adsorption column of a cation exchange resin filled with a hydrogen ion type (hereinafter referred to as "H type") to adsorb TAA ions to the cation exchange. Resin.

That is, the TAA ion is a cation, and is ion-exchanged with the hydrogen ion of the cation exchange resin by contact with the H-type cation exchange resin to be adsorbed to the resin. Therefore, TAA ions can be recovered from the waste liquid more efficiently. In particular, TAA ions can be recovered at low cost in a waste liquid having a low TAAH concentration.

Here, in general, the metal ion impurity is also a cation, and is adsorbed to the cation exchange resin by passing through the liquid as described above. In the present invention, the metal ion impurities adsorbed to such a cation exchange resin are more efficiently separated from the TAA ions by the method described later. Further, even if there is a metal ion impurity, a chemical equilibrium reaction such as formation of a complex in the developing waste liquid, when the ion species contained in the metal itself is an anion, is difficult to adsorb to the cation exchange resin and is discharged from the adsorption tower.

On the other hand, the organic component from the photoresist which is dissolved as described above is usually in an anionic form, so that it is difficult to adsorb to the cation exchange resin and most of it is removed, and only a part of it is adsorbed to the ion exchange resin, so the recovery step of the TAA salt is continued. The TAA salt solution is mixed in (the removal of the organic component described herein will be described later).

(cation exchange resin)

In the present invention, the cation exchange resin that adsorbs the above TAA ions is not particularly limited, and a known one can be used. Specifically, any of the strongly acidic cation exchange resins in which the ion exchange group is a sulfonic acid group and the weakly acidic cation exchange resin in which the ion exchange group is a carboxylic acid can be used. Among these, a weakly acidic cation exchange resin is preferably used from the viewpoint that the ion exchange capacity is large and the amount of the resin to be used is lowered. Further, in the case of a weakly acidic cation exchange resin, elution of TAA ions to be described later is also easy.

Further, the structure of the resin may be a gel type or a MR type (microporous type). The shape of the resin may be any of powder, granule, film, and fiber. From the viewpoints of processing efficiency, workability, economy, and the like, it is preferred to use a cation exchange resin such as styrene or propylene.

The counter ion of the cation exchange resin is usually sold as hydrogen ion (H type) or sodium ion (Na type), but in order to prevent the finally obtained TAAH solution from mixing sodium ions and increasing the adsorption efficiency of the TAA ion, the counter ion is Hydrogen ion type H type. In the case of using a commercially available cation exchange resin of the Na type, an acid such as hydrochloric acid or sulfuric acid is introduced into the cation exchange resin in advance, and the mixture is sufficiently washed with ultrapure water to use the counter ion as a hydrogen ion. Further, according to the method described later, after the TAA ions are dissolved, the same alkali metal type such as Na can be formed. Operation, and then generate H type and use.

Specific examples of the strongly acidic cation exchange resin are, for example, Amberlite IR120B manufactured by Rohm and Haas Co., Ltd., Amberlite IR124; DIAION SK1B manufactured by Mitsubishi Chemical Corporation, DIAION PK228; Duolite C255LFH manufactured by Chem Chemex; manufactured by LANXESS LEWATIT Monoplus S100, Purolite C160 manufactured by Purolite. Specific examples of the weakly acidic cation exchange resin are, for example, Amberlite IRC76 manufactured by Rohm and Haas Co., Ltd., DIAION WK40L manufactured by Mitsubishi Chemical Corporation, Duolite C433LF manufactured by Sumitomo Chemtex Co., Ltd., Duolite C476, and LEWATIT CNP80WS manufactured by LANXESS Co., Ltd. , Purolite C104 manufactured by Purolite Co., Ltd., and the like.

(Method of introducing a cation exchange resin adsorption column into a solution)

In the present invention, a solution containing a metal ion and TAAH is introduced into an adsorption column packed with the above-mentioned H-type cation exchange resin, and TAA ions are adsorbed to the cation exchange resin by contact with a cation exchange resin.

For the method of passing the solution into an adsorption column packed with a cation exchange resin, a conventional method can be suitably employed depending on the type or shape of the cation exchange resin. Specifically, for example, a column in which a cation exchange resin is packed in a column and the solution is continuously passed is preferred. In the case of the column method, the performance of the cation exchange resin may be appropriately determined, but in order to adsorb TAA ions more efficiently, if the content of TAAH is 0.001 to 1% by mass, the height (L) of the column and the column The ratio (L/D) of the diameter (D) is 0.5 or more, and the space velocity (SV) of the waste liquid is preferably 1 (1/hour) or more and 200 (1/hour) or less.

The amount of solution passing through the solution is not more than the cation exchange filled in the adsorption tower It is preferable to change the amount of the resin, but to manufacture the TAA salt more efficiently.

Further, a solution containing a cation or more of a cation exchange resin having a cation exchange amount or more is allowed to flow out (leakage) of TAA ions without adsorption, and TAA in the liquid flowing out through the adsorption tower can be analyzed by ion chromatography. Confirmed by ion concentration. More simply, the height of the cation exchange resin in the adsorption column can be determined. When the counter ion of the cation exchange resin is changed from a hydrogen ion to a TAA ion, the volume is swollen to about 2 times depending on the type of the cation exchange resin. The adsorption of TAA ions can be confirmed by measuring the volume of the cation exchange resin.

Further, in the case where the pH of the solution is 10 or more, when the TAA ions pass through the adsorption tower without being adsorbed, the pH of the liquid to be passed becomes alkaline, and it can be confirmed by a pH pH meter. Further, in the case where the liquid in the adsorption tower contains TAA ions, since the conductivity of the liquid rises, it can also be confirmed by the conductivity.

(Step of recovering tetraalkylammonium salt from a cation exchange resin adsorbing tetraalkylammonium ions)

In the present invention, after the TAA ions are adsorbed to the cation exchange resin by the above method, a solution of an alkali metal salt is introduced into the adsorption column filled with the cation exchange resin, and the recovered liquid flowing out from the adsorption column is recovered to produce a tetraalkylammonium salt.

That is, the solution of the alkali metal salt is introduced into the adsorption tower from one end of the adsorption tower, and the liquid flows out at the other end to carry out liquid introduction, and the excess alkali metal ions contained in the salt solution are exchanged with TAA ions, and used as TAA ions. The salt of the salt flows out of the adsorption column.

The alkali metal is preferably from the viewpoint of solubility or easy availability. Sodium or potassium, especially sodium.

In the present invention, the above alkali metal salt may be a mineral acid salt or an organic acid salt. It may also be a salt of a weak acid or a salt of a strong acid. The weak acid is an acid having a dissociation constant K of 10 to ³ or less at 25 °C.

The TAA salt produced by the method of the present invention provides an electrolysis step to be described later, and the alkali metal salt is preferably a mineral acid salt from the viewpoint that it is difficult to cause adverse effects such as the incorporation of an organic component when converted to TAAH. The inorganic acid is, for example, carbonic acid, nitrous acid, hydrofluoric acid, hypochlorous acid or the like. The organic acid is a carboxylic acid such as acetic acid, oxalic acid, formic acid or benzoic acid, or a phenol or a cresol.

Among the inorganic acid salts, carbonates are preferred from the viewpoints of toxicity, stability, ease of electrolysis in the formation of TAAH, and the like. The alkali metal carbonate of the dibasic acid is a carbonate (M ₂ CO ₃ : M alkali metal) and a hydrogencarbonate (MHCO ₃ ), but from the viewpoint of further increasing the concentration of TAA ions in the recovered liquid, carbonic acid is preferred. salt. Particularly suitable alkali metal salts in the present invention are, for example, sodium carbonate, sodium hydrogencarbonate, potassium carbonate and potassium hydrogencarbonate, among which sodium carbonate is most preferred.

The solvent constituting the weak acid salt solution of the alkali metal used in the present invention is a liquid capable of dissolving the alkali metal salt, and is not particularly limited. However, the ease of dissolution of the alkali metal salt, the cost, and the electrolysis for the production of TAAH are not The viewpoint of generating a negative influence is preferably water. As the water, ion-exchanged water, pure water, ultrapure water or the like can be used.

In the present invention, the concentration of the alkali metal salt solution can be appropriately selected in the range of 0.1 N to 10 N, but it is preferably in the range of 0.5 N to 4 N from the viewpoint of flowing out a high concentration of TAA salt and easily preventing the incorporation of metal ions. .

The flow rate of the alkali metal salt solution depends on the volume and yang of the adsorption tower. The type and amount of the ion exchange resin, the concentration of the salt solution, and the like can be appropriately set. However, the space velocity (SV) of the alkali metal salt solution is preferably 1 (1/hour) or more and 50 (1/hour) or less. When it is smaller than this range, the processing time will be prolonged.

The method of contacting the alkali metal salt solution with the TAA ion and the cation exchange resin having a counter ion is preferably a column method in which the cation exchange resin is filled in a column to continuously pass the alkali metal salt solution. In the case of the column method, from the viewpoint of effective operation, it is preferred to use the same column, and the cation exchange resin filled in the column adsorbs TAA ions, and then the alkali metal salt solution is preferably passed.

(recycling of effluent)

The TAA ion at one end of the adsorption column is passed through the alkali metal salt solution, and the anion of the salt to be used (for example, CO ₃ ^2- if carbonate is used) is a counter ion, and a TAA salt is eluted (dissolved), and the effluent is formed. The liquid is recovered in the storage tank.

One of the features of the present invention is that the concentration of the alkali metal ions in the effluent is measured, and the point at which the recovery of the storage tank is stopped before the increase in the concentration of the alkali metal ions is rapidly increased.

That is, the cation exchange resin in the adsorption tower adsorbs metal ions in addition to the TAA ions as described above, but by passing the alkali metal salt solution into the adsorption tower, the TAA ions are exchanged with the alkali metal ions, preferentially flowing out (dissolution). . On the other hand, other metal ions are maintained in the original state of the ion exchange resin. Further, when the alkali metal salt solution is continuously supplied, the metal ions originally coexisting in the TAA solution start to dissolve with the alkali metal ions constituting the alkali metal salt solution introduced into the adsorption column. Since the original concentration of the metal ion originally coexisting in the TAA solution is relatively thin, it is difficult to directly detect the start of the outflow. Here, according to the present inventors, etc. In the review, the elution behavior of these metal ions shows the same tendency as the elution behavior of the alkali metal ions introduced into the adsorption column at a high concentration, and the elution is started before and after, so that the dissolution behavior of the alkali metal ions is measured to make the alkali metal ions have a high concentration. The effluent is not mixed with the recovery liquid containing TAA ions which hardly contain metal ions, and a recovery liquid containing a high concentration of TAA ions and having a large concentration of each metal ion can be obtained.

More specifically, in the adsorption tower filled with the cation exchange resin adsorbing TAA ions, even if the alkali metal salt solution is introduced, the concentration of the alkali metal ions in the initial effluent is extremely low (usually less than 0.1 ppm) and stabilized. However, when the TAA ion exchanges with the alkali metal ion, the alkali metal ion concentration starts to rise sharply, far exceeding 1 ppm, reaching tens to hundreds of ppm. At this time, only the portion immediately before the rise is recovered in the storage tank, and the subsequent effluent is separately separated, whereby a TAA salt having high recovery and high purity can be obtained.

The criterion for determining whether or not the alkali metal ion concentration starts to rise sharply is that when the measurement unit of the alkali metal ion concentration is extremely sensitive, it is 10 to 10,000 times, preferably 10 to 5,000, which is set to a stable value. Before any concentration (specific value) of the double point, it is preferred to stop the recovery of the storage tank just before reaching any concentration.

On the other hand, when a measurement unit having a low sensitivity such as an ion electrode is used, the initial stability value may be less than the measurement lower limit value. In this case, the recovery of the storage tank can be stopped before the alkali metal ion concentration is set to any concentration (specific value) between 0.5 and 10 mg/L. For example, when the measurement limit of a general alkali metal ion electrode is usually 1 mg/L, it is recovered in the storage tank below the lower limit of the measurement, and the effluent after the value of 1 mg/L is stopped and stored. groove.

The method of stopping the recovery of the effluent from the storage tank before reaching the concentration of the alkali metal ions of the above specific value is not particularly limited, and for example, as shown in Fig. 1, below the apparatus (metal ion electrode) for measuring the concentration of the alkali metal ions The flow path switching valve is provided, and the method of switching the flow path of the valve and the like while the alkali metal ion concentration rises to a specific value in the metal ion electrode induced effluent.

When the metal ion concentration of the effluent reaches a specific value, the liquid can be stopped from flowing out of the adsorption tower by itself. However, in order to regenerate the cation exchange resin and reuse it, it is preferable to change the flow path of the switching valve or the like. The unit recovers the effluent flowing to another storage tank or the like in the storage tank.

A method of measuring the metal ion concentration can be suitably carried out by a conventional method. Specifically, for example, a method of measuring a certain amount of the effluent flowing out of the adsorption tower, measuring a metal ion using a metal ion electrode or the like, or measuring an inline type metal ion electrode in a line for introducing the effluent into the storage tank is used. Method, etc. If an inline type metal ion electrode is used, the liquid can be stopped at the moment when the metal ion concentration reaches a specific value without being taken out in the middle, and the loss of the recovered liquid can be suppressed.

It is mainly based on the measured time interval and must be changed according to the flow rate (flow rate) of the effluent. In the case where the solution is flowed at a high flow rate, the change in the concentration of the metal ions of the effluent occurs rapidly, and therefore, in order to obtain a liquid of a desired property (concentration of metal ion impurities), the interval of measurement must be shortened.

(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 electrodialysis, electrolysis or the like in the above method.

Moreover, the purification or concentration of the resulting TAA salt can be carried out prior to electrodialysis or electrolysis. The method for purifying the TAA salt solution, for example, a method in which the TAA salt solution is contacted with a cation exchange resin (but a counter ion is replaced with a TAA ion in advance) and/or a chelate resin, and a metal ion component in the TAA salt is removed, or a TAA salt is used. A method of removing an organic substance such as a photoresist by contact with an adsorbent such as activated carbon or an anion exchange resin.

The method of concentrating the TAA salt is specifically, for example, a method of concentrating by electrodialysis, an evaporation can, a reverse osmosis membrane, or the like.

(Manufacture of TAAH: Electrolysis step of TAA salt)

The electrolysis step of electrolyzing the obtained TAA salt to form TAAH is not particularly limited, and a known method can be used depending on the type of the TAA salt to be recovered (corresponding to the acid component constituting the alkali metal salt to be used). For example, in the case where the recovered TAA salt is a carbonate, it is preferred to use an anode, a cathode, or a cation exchange membrane as described in Japanese Patent No. 3109525 (dielectric chamber: raw material supplied to the anode chamber), and it is preferred that the TAA salt form TAAH.

Example

In order to explain the present invention more specifically, the following examples and comparative examples are described, but the present invention is not limited thereto.

(Regeneration treatment of cation exchange resin (H-type cation exchange resin))

The cation exchange resin used is filled in a glass column at the time of use, and ultrapure water, 1N HCl (hydrochloric acid) and ultrapure water are sequentially introduced, and the counter ion is a hydrogen ion. Each liquid was passed at a space velocity SV = 5 (1/hour), and the liquid amount of each liquid was 10 L/L-resin.

(concentration determination)

The concentration of tetramethylammonium hydroxide (TMAH) and tetramethylammonium salt (TMA salt) was analyzed by ion chromatography.

Specifically, using ICS2000 manufactured by DIONEX, in the cation analysis, the column uses ION-pac CS12A, in the anion analysis, the column uses ION-pac AS15, the cation analysis uses the methane sulfonic acid in the solution, and the anion analysis in the solution Analysis was carried out using potassium hydroxide.

The concentration of the metal ions contained in the solution is determined by an ion electrode (portable water quality) method (model: IM-32P (manufactured by East Asia DKK)), high frequency induced combined plasma mass spectrometry (ICP-MS) method (measurement device: HP-4500 (manufactured by Agilent Co., Ltd.) and high-cycle induced plasma-infrared spectroscopy (ICP-OES) method (measurement apparatus: iCAP 6500 DUO (manufactured by THERMO ELECTRON)). If not limited, each concentration is a quality basis.

Example 1

(TMA ion waste liquid adsorption step)

1000 ml of a weakly acidic cation exchange resin DIAION WK40L (manufactured by Mitsubishi Chemical Corporation) was packed in a column having a diameter of 50 mm, and the resin height was 510 mm.

In the above column, 0.045 mass% of TMAH waste liquid (photoresist developing waste liquid was introduced at SV (space velocity) = 100 (1/hour), the photoresist content was 10 ppm in terms of COD, and the metal ion concentration: Na: 2.5 Ppb, K: 5.4 ppb, Ca: 4.1 ppb, Al: 3.2 ppb, Ni: 2.0 ppb, Cu: 2.0 ppb, Cr: 2.5 ppb, Fe: 5.3 ppb) 1000 L, for adsorption of TMA ions.

(Solution step of TMA ions)

Thereafter, 5000 ml of 2N sodium carbonate as a solution was introduced at SV = 4 (1/hour), and the adsorbed TMA ions were dissolved to form TMA carbonate. flow The liquid was separated by 500 ml each time, and 10 liquids were respectively taken out (liquids A to J, respectively). The TMA carbonate concentration and the metal ion concentration of these respective liquids were measured. The results are shown in Table 1.

As is clear from the results in Table 1, the sodium ion concentration is equal to or higher than the lower limit value, and the metal ion concentration is increased. The recovery amount in the respective liquids C to H recovery was 3000 ml, and the concentration of TMA carbonate was 9.7% by mass (0.46 mol/l).

Example 2

(TMA ion adsorption step)

1000 ml of a weakly acidic cation exchange resin LEWATIT CNP80WS (manufactured by LANXESS Co., Ltd.) was packed in a column having a diameter of 50 mm, and the resin height was 510 mm.

In the above column, 0.045 mass% of TMAH waste liquid (photoresist developing waste liquid was introduced at SV (space velocity) = 100 (1/hour), the photoresist content was 10 ppm in terms of COD, and the metal ion concentration: Na: 2.5 Ppb, K: 5.4 ppb, Ca: 4.1 ppb, Al: 3.2 ppb, Ni: 2.0 ppb, Cu: 2.0 ppb, Cr: 2.5 ppb, Fe: 5.3 ppb) 1000 L, for adsorption of TMA ions.

(Solution step of TMA ions)

Thereafter, 5000 ml of 2N potassium carbonate as a solution of the TMA ion dissolving step was introduced at SV = 5 (1/hour), and the adsorbed TMA ions were formed into TMA carbonate to be dissolved. The effluent was sequentially dispensed in 500 ml each time, and 10 liquids (separate liquids A to J) were taken out respectively. The TMA carbonate concentration and the metal ion concentration of these respective liquids were measured. The results are shown in Table 2.

As is clear from the results in Table 2, the potassium ion concentration is equal to or higher than the lower limit value, and the metal ion concentration is increased. The recovery amount in the liquid C to H recovery was 3,000 ml in total, and the concentration of TMA carbonate was 9.1% by mass (0.44 mol/l).

Example 3

(TMA ion adsorption step)

1000 ml of a weakly acidic cation exchange resin Duolite C476 (manufactured by Sumitomo Chemtex Co., Ltd.) was packed in a column having a diameter of 50 mm, and the resin height was 510 mm.

0.045 mass% of TMAH waste liquid (photoresist developing waste liquid, photoresist content in COD) was introduced into the above column at SV (space velocity) = 100 (1/hour) Conversion to 10 ppm, metal ion concentration: Na: 2.5 ppb, K: 5.4 ppb, Ca: 4.1 ppb, Al: 3.2 ppb, Ni: 2.0 ppb, Cu: 2.0 ppb, Cr: 2.5 ppb, Fe: 5.3 ppb) 1000 L, Adsorption of TMA ions.

(Solution step of TMA ions)

Thereafter, 8000 ml of 1 N sodium carbonate as a solution of the TMA ion dissolving step was introduced at SV = 3 (1/hour), and the adsorbed TMA ions were dissolved to form TMA carbonate. The effluent was sequentially dispensed in 500 ml each time, and 16 liquids (liquids A to P, respectively) were taken out. The TMA carbonate concentration and the metal ion concentration of these respective liquids were measured. The results are shown in Table 3.

As is clear from the results in Table 3, the concentration of the metal ion is increased by the N concentration of the sodium ion or more. The recovery amount of the respective liquids C to M was 5,500 ml, and the concentration of TMA carbonate was 6.2% by mass (0.30 mol/l).

Example 4

(purification step)

A 50 mm diameter column (resin height 510 mm) filled with a chelating resin (Duolite C747 manufactured by Rohme and Haas Co., Ltd.) which had been previously contacted with hydrochloric acid or ultrapure water and subjected to regeneration treatment, and a cation exchange resin (Rohme and filled) were prepared. Amberlist 15J manufactured by Haas Co., Ltd. 1000 ml diameter 50 mm column (resin height 510 mm).

The respective liquids C to H of Example 1 were introduced into the above-mentioned chelate resin column to obtain a treatment liquid A. Thereafter, the treatment liquid A is introduced into a cation exchange resin column to obtain a treatment liquid B. Liquid analysis was performed on the treatment liquids A and B, and the results are shown in Table 4.

Example 5

The treatment liquid B obtained in Example 4 was concentrated by an evaporation concentration device to a TMA carbonate concentration of 26.1% by mass. The obtained TMA carbonate was subjected to an electrolysis step to produce TMAH.

For the electrolysis step, a two-chamber type electrolytic cell equipped with an anode, a cation exchange membrane (Nafion 90209 (manufactured by DuPont)), and a cathode was used. The ion exchange membrane has an effective membrane area of ² dm ² and the Nafion membrane has a carboxylic acid group facing the cathode side. The anode was made of a platinum plated platinum plate and the cathode was made of SUS 316. The anode chamber of the above electrolytic cell was circulated with TMA carbonate, the cathode chamber was circulated with pure water, the current density was 18 A/dm ² , the temperature was maintained at 40 ° C, and electrolysis was continuously performed at the same time. In the continuous operation, the TMAH concentration of the cathode chamber was 18% by mass. Similarly, the concentration of the liquid circulating in each chamber is maintained constant, and pure water is added when the concentration becomes rich, and the components are added when it is diluted.

After the start of electrolysis, the operation state was stabilized, and after 12 hours (safety) and continuous operation for 3 months, the analysis results of the obtained TMAH are shown in Table 5.

Comparative example 1

The same procedure as in Example 1 was carried out except that the effluent in Example 1 was measured without measuring the metal ion electrode and the conductivity and pH were measured. In the TMA ion dissolving step, the effluent was sequentially dispensed in 500 ml each time, and 10 liquids (respectively liquids A to J) were taken out. The TMA carbonate concentration, metal ion concentration, conductivity, and pH of these respective liquids were measured. The results are shown in Table 6.

From the results of Table 6, it is understood that there is no difference in the rate of change in conductivity or pH between the respective liquids H and I in which sodium ions are mixed. In the case where the alkali metal salt is an eluent, it is difficult to control the incorporation of metal ion impurities in the recovered liquid at the conductivity or the pH.

Claims (6)

A method for producing a tetraalkylammonium salt solution, which is a method for obtaining a tetraalkylammonium salt solution containing a solution of a tetraalkylammonium salt having a reduced ratio of metal ions from a solution containing a metal ion and a tetraalkylammonium hydroxide solution The method comprises the steps of: (1) and (2): (1) introducing a metal ion and a tetraalkylammonium hydroxide into an adsorption tower filled with a hydrogen ion type cation exchange resin; a solution for adsorbing a tetraalkylammonium ion in the solution to a cation exchange resin; (2) in the adsorption step, an alkali metal salt is introduced into an adsorption column of a cation exchange resin that adsorbs tetraalkylammonium ions. a solution in which a tetraalkylammonium ion adsorbed to the resin forms a salt and dissolves, and the effluent from the adsorption tower is recovered to a recovery step of the storage tank; and in the recovery step, the outflow from the adsorption tower is measured The concentration of the alkali metal ions in the liquid stops the recovery of the effluent from the storage tank before the concentration of the alkali metal ions rises sharply. A method for producing a tetraalkylammonium salt solution, which is a method for obtaining a tetraalkylammonium salt solution containing a solution of a tetraalkylammonium salt having a reduced ratio of metal ions from a solution containing a metal ion and a tetraalkylammonium hydroxide solution The method comprises the steps of: (1) and (2): (1) introducing a metal ion and a tetraalkylammonium hydroxide into an adsorption tower filled with a hydrogen ion type cation exchange resin; a solution for adsorbing a tetraalkylammonium ion in the solution to a cation exchange resin; (2) in the adsorption step, filling an adsorption column of a cation exchange resin adsorbing tetraalkylammonium ions, and introducing an alkali metal salt a solution that adsorbs to the resin a tetraalkylammonium ion is formed by dissolving the salt described above, and recovering the effluent from the adsorption tower to a recovery step of the storage tank; and in the recovering step, measuring the concentration of the alkali metal ion in the effluent flowing out of the adsorption tower, When the concentration of the alkali metal ion is set to a specific concentration between 0.5 and 10 mg/L, the recovery of the effluent from the storage tank is stopped. The method for producing a tetraalkylammonium salt solution according to claim 1 or 2, wherein the alkali metal salt is selected from the group consisting of sodium carbonate, sodium hydrogencarbonate, potassium carbonate and potassium hydrogencarbonate. One or two or more. A method for producing a tetraalkylammonium hydroxide, which comprises the method according to any one of claims 1 to 3, after preparing a tetraalkylammonium salt solution, and using the obtained tetraalkylammonium salt as The raw material is used to produce tetraalkylammonium hydroxide. The method for producing a tetraalkylammonium hydroxide according to claim 4, wherein the method for producing a tetraalkylammonium salt solution according to any one of claims 1 to 3, wherein hydrogen is produced The metal ion impurities contained in the tetraalkylammonium salt are removed by the chelating resin and/or the cation exchange resin before the tetraalkylammonium oxide is oxidized. The method for producing a tetraalkylammonium hydroxide according to any one of claims 1 to 3, wherein the method for producing a tetraalkylammonium salt solution is further produced by the method according to any one of claims 1 to 3. A step of concentrating the solution is included.