JPH0333792B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel production method for obtaining highly pure quaternary ammonium hydroxide from a quaternary ammonium salt.

[Prior art and problems] Quaternary ammonium hydroxide aqueous solution is used as an organic alkaline agent that does not contain metal ions, for example.
The use of cleaning agents for semiconductor substrates, resist removers, etc. in the manufacture of semiconductor devices such as ICs and LSIs is expanding. A highly purified quaternary ammonium hydroxide aqueous solution containing extremely few substances is required.

On the other hand, as a method for producing quaternary ammonium hydroxide, an aqueous solution of quaternary ammonium salts such as quaternary ammonium chloride and quaternary ammonium sulfate is charged into the anode chamber using an electrolytic cell using a cation exchange membrane as a diaphragm. It was known to supply quaternary ammonium hydroxide in the cathode chamber by electrolysis.

However, in the production method using such a diaphragm electrolytic cell, the anions of the quaternary ammonium salt, which is the raw material supplied to the cathode chamber, permeate the diaphragm and diffuse into the cathode chamber. The amount of impurity ions in the resulting quaternary ammonium hydroxide aqueous solution increases, and the number of anionic impurities in the resulting quaternary ammonium hydroxide aqueous solution increases.
The concentration is ppm or higher.

On the other hand, as another method for producing quaternary ammonium hydroxide, there is a method in which an aqueous quaternary ammonium salt solution is directly brought into contact with an OH type ion exchange resin layer. However, when attempting to obtain highly pure quaternary ammonium hydroxide by such an ion exchange method, it is necessary to increase the flow-through exchange capacity, and a large amount of ion exchange resin must be used. In addition, large amounts of high-purity caustic soda and water are required to regenerate the ion exchange resin.
Recycling such a large amount of ion exchange resin is extremely disadvantageous industrially.

[Means for Solving the Problem] As a result of repeated research in order to solve the above problem, the present inventors electrolyzed a quaternary ammonium salt aqueous solution to obtain a quaternary ammonium hydroxide aqueous solution. It has been discovered that by bringing this into contact with an OH type anion exchange resin, the impurity ions can be removed extremely efficiently and highly pure quaternary ammonium hydroxide can be obtained, leading to the completion of the present invention.

In the present invention, a quaternary ammonium salt aqueous solution is electrolyzed in a diaphragm electrolytic cell to obtain a quaternary ammonium hydroxide aqueous solution, and then the aqueous solution is converted into a quaternary ammonium salt aqueous solution containing 10 ppm or less of anions other than hydroxide ions. Following the treatment with caustic alkali, the anion is removed by washing with pure water with a specific resistance of 10 MΩ-cm or more until the metal ions in the washing water become 0.01 ppm or less and contacting it with a purified OH-type anion exchange resin. This is a method for producing an aqueous quaternary ammonium hydroxide solution, characterized in that the ionic impurity concentration is 0.2 ppm or less.

The quaternary ammonium salt used as a raw material in the present invention has the general formula (However, R ₁ to _{R 4} are an alkyl group or a derivative thereof, or an aromatic group or a derivative thereof,
Each R may be the same or different.) A salt having R may be used without particular restriction. Specific examples of R ₁ to _{R 4} include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl, and methoxymethyl. groups, alkoxyalkyl groups such as methoxyethyl groups and methoxypropyl groups, phenyl groups, tolyl groups,
Aromatic groups such as xylyl group, benzyl group, phenethyl group, styryl group and derivatives thereof are mentioned. Further, X may be a halogen ion such as a chloride ion or a bromide ion, or an acid group such as a sulfate ion, a nitrate ion, or a phosphate ion. The method of the present invention is particularly effective because the amount of permeation is large.

The diaphragm electrolytic cell and electrolytic method used in the present invention may be any known cell and method without particular limitation. That is, using a diaphragm electrolytic cell in which a diaphragm is provided between the negative and anode to form an anode chamber and a cathode chamber, a quaternary ammonium salt aqueous solution as a raw material is supplied to the anode chamber, and water or hydroxide is supplied to the cathode chamber. A quaternary ammonium aqueous solution is supplied to perform electrolysis of the quaternary ammonium salt. It is particularly preferable to use a cation exchange membrane as the diaphragm of such a diaphragm electrolytic cell in order to control the amount of anions produced from the quaternary ammonium salt in the anode chamber dialyzed into the cathode chamber. Furthermore, in the above electrolytic cell, an intermediate chamber partitioned by a diaphragm is formed between the cathode chamber and the anode chamber, and a quaternary ammonium hydroxide aqueous solution is supplied to the intermediate chamber for electrolysis. This is a preferred embodiment because the permeation of anions from the anode chamber into the resulting quaternary ammonium hydroxide aqueous solution is further reduced, and the throughput per unit of the OH type anion exchange resin can be increased. In addition, the concentration of the quaternary ammonium salt aqueous solution supplied to the anode chamber is generally
0.1 to 50% by weight, especially 1 to 10% by weight are preferred.

Next, in the present invention, the quaternary ammonium hydroxide aqueous solution obtained from the cathode chamber of the electrolytic cell is treated with caustic alkali containing 10 ppm or less of anions other than hydroxide ions, and then the resistivity is reduced to 10 MΩ-
Use pure water of cm or higher to remove metal ions in the wash water.
In order to obtain highly pure quaternary ammonium hydroxide, it is important to contact it with an OH type anion exchange resin that has been purified by washing with water until the concentration is 0.01 ppm or less.

As the OH type anion exchange resin, any known anion exchange resin can be used without particular limitation. For example, a strongly basic anion exchange resin in which a styrene and DVB copolymer is chloromethylated and then aminated with trimethylamine, or a strongly basic anion exchange resin in which dimethylethanolamine is used instead of trimethylamine is suitable. It is.
The shape of the OH type ion exchange resin is not particularly limited either, but it is generally granular, tubular, sheet-like, or the like.

The method of contacting the quaternary ammonium aqueous solution obtained from the cathode chamber with the OH type ion exchange resin may be appropriately determined depending on the shape of the resin and the like. For example, in the case of a granular ion exchange resin, a common method is to fill a packed column with the resin and pass an aqueous quaternary ammonium hydroxide solution through the column. Through this contact treatment, the anions in the quaternary ammonium hydroxide aqueous solution are ion-exchanged with hydroxide ions, and an extremely pure quaternary ammonium hydroxide aqueous solution is obtained.

The purpose of the present invention is that anionic impurities are
The OH type anion exchange resin used to obtain extremely high purity quaternary ammonium hydroxide of 0.2 ppm or less requires extremely high degree of purification.
In the present invention, treatment is performed with a caustic alkali containing 10 ppm or less of anions other than hydroxide ions, such as sodium hydroxide, potassium hydroxide, quaternary ammonium hydroxide, etc., and then the resistivity is reduced to 10 MΩ-
Metal ions in the washing water are removed using pure water of cm or more.
It must be used after being washed and purified to a concentration of 0.01 ppm or less.

In the present invention, the quaternary ammonium hydroxide aqueous solution obtained from the cathode chamber of the electrolytic cell is introduced into the desalination chamber of the electrodialysis cell before or after contacting with the OH type ion exchange resin, and the quaternary ammonium ions are permeated. Conducting electrodialysis with an amount of electricity within a range that does not increase the amount of electricity is a more preferable embodiment, since even trace amounts of metal ions present in the aqueous quaternary ammonium hydroxide solution can be removed. In addition, in the present invention, OH
The quaternary ammonium hydroxide aqueous solution that has been brought into contact with the mold exchange resin may be further electrolyzed. In this case, the amount of impurity ions diffused in the second stage electrolysis is significantly reduced, so that OH type ions This method has the advantage that it is not necessary to use the above-mentioned highly purified regenerant for the exchanged resin.

[Effect] As understood from the above explanation, according to the method of the present invention, in the electrolytic synthesis of a quaternary ammonium hydroxide aqueous solution using a quaternary ammonium salt as a raw material, quaternary It is possible to efficiently remove the anion of the grade ammonium salt and obtain a highly purified aqueous ammonium hydroxide solution in high yield.

[Examples] Examples are shown below to further specifically explain the present invention, but the present invention is not limited thereto.

Example Cation exchange membrane (manufactured by Tokuyama Soda, Neocepta C66)
-10F) is used as a diaphragm in a two-chamber electrolytic cell (anode Ti/
A 5% tetramethylammonium chloride aqueous solution was supplied to the anode chamber of the Pt, cathode SUS316), and 1% tetramethylammonium hydroxide was placed in the cathode chamber, and the concentration in the cathode chamber gradually increased as it passed through at 2A/ ^dm2 . The electrolysis was terminated when about 5% tetramethylammonium hydroxide was obtained. This 5%
When Cl ^- in tetramethylammonium hydroxide was measured, it was approximately 40 ppm.

On the other hand, a type of commercially available anion exchange resin is placed in a packed tower and thoroughly conditioned, followed by high purity 5. It was made into OH form using % NaOH solution.

Next, the regenerant NaOH was extruded and washed with water using ultra-pure resin (specific resistance 10 MΩ-cm or more) produced using a conventional mixed-bed ion exchange resin column until the Na ⁺ ions became 0.01 ppm or less as determined by atomic absorption spectrometry. I went. When the tetramethylammonium hydroxide obtained by the above method was passed through an OH type anion exchange resin column purified by the above method and treated, the Cl ^- ions in the distillate were reduced to about 0.2 ppm. was.

Claims (1)

[Claims] 1. After obtaining a quaternary ammonium hydroxide aqueous solution by electrolyzing a quaternary ammonium salt aqueous solution in a diaphragm electrolytic cell, the aqueous solution is treated with a caustic alkali containing 10 ppm or less of anions other than hydroxide ions. Following the treatment, anionic impurities are removed by contacting purified OH-type anion exchange resin with purified water using pure water with a specific resistance of 10 MΩ-cm or more until the metal ions in the washing water become 0.01 ppm or less. concentration
A method for producing a quaternary ammonium hydroxide aqueous solution, characterized in that the concentration is 0.2 ppm or less.