JPS59193289A - Preparation of high-purity quaternary ammonium hydroxide - Google Patents

Abstract

PURPOSE:To obtain a high-purity quaternary ammonium hydroxide in which an extremely small amount of impurities such as alkali (alkline earth) metals is incorporated, by electrodialyzing an aqueous quaternary ammonium hydroxide solution obtd. by the electrolysis of an aqueous quaternary ammonium salt solution by an ion-exchange membrane method. CONSTITUTION:A quaternary ammonium salt (e.g. tetramethyl ammonium chloride) as an aqueous solution is supplied to the anodic chamber of an electrolytic cell having a diaphragm (e.g. a cation-exchange membrane) or a composite membrane. The temp. of a liquid in the electrolytic cell is held below 50 deg.C, and DC voltage is impressed under the condition of current density of 1-100A/dm<2> to obtain an aqueous quaternary ammonium hydroxide solution from a cathodic chamber. Then, said aqueous solution is electrodialyzed using an electrodialysis cell having three or more chambers for dialysis each divided from the other with cation- and anion-exchange membranes in a manner such that the chambers at both ends are handled as cathodic and anodic chambers, respectively. As a result, a high-purity quaternary ammonium hydroxide in which the amounts of impurities such as alkali (alkaline earth) metals derived from a raw material are extremely reduced is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing high purity quaternary ammonium hydroxide from quaternary ammonium salts.

Quaternary ammonium hydroxide is useful as a strong basic organic compound that does not contain metal ions, and is used for analysis as a base standard solution for non-aqueous titration of weak acids, as an additive to paint vehicles, as a silica sol, It is widely used as an additive to binders such as alkali silicate, and also as a special cleaning agent and developer in the manufacture of I'C substrates in the electronic industry. The demand for developing solutions is increasing, but in this case, it is not possible to fully achieve the purpose by using highly pure products.However, conventional manufacturing methods that simply electrolytically treat quaternary ammonium salt aqueous solutions For example, impurities such as alkali metals, alkaline earth metals, and anions derived from raw materials are mixed into the product quaternary ammonium hydroxide, and if this product is used as a developer or remover for positive-type photosensitive resins, for example, , dissociated metal ions, which are impurities, significantly impair the electrical characteristics of semiconductor devices.

As a result of intensive research into a method for obtaining high-purity quaternary ammonium hydroxide containing no impurities, the present inventor noticed that alkali metal ions, alkaline earth metal ions, etc. have high electrical mobility. The present invention was completed based on the idea that the quaternary ammonium hydroxide aqueous solution obtained by electrolysis should be further subjected to electrodialysis treatment.

That is, the present invention is characterized in that an aqueous solution of a quaternary ammonium salt is electrolyzed in an electrolytic cell having a diaphragm or a composite membrane to obtain an aqueous solution of a quaternary ammonium hydroxide, and then this is subjected to ion exchange desorption electrodialysis. shall be.

The electrolytic cell used in the method of the present invention may be of a conventional type in which an anode and a cathode are provided on each opposing surface of a diaphragm, and any type of diaphragm may be used as long as it is porous.

Examples include porous plastic diaphragms such as cation exchange membranes, unglazed magnetic diaphragms, asbestos fiber diaphragms, sintered glass diaphragms, polymerized vinyl compound membranes, and fluororesin membranes.

As for the material constituting the electrode, the anode is preferably a stable material that is durable against halogens, oxygen, etc. generated by electrolysis of quaternary ammonium salts, and materials such as lead, lead alloys, and various metals coated with platinum group metals. It is appropriate to use electrodes. Further, in the case of the anode, the material for the cathode is not required to have chemical stability, and for example, iron, nickel, carbonate, carbon, and alloys thereof are sufficient. Of course, the platinum group coated electrode mentioned for the anode may also be used.

In the present invention, electrolysis can be carried out using an electrolytic cell divided into an anode chamber and a cathode chamber by a composite membrane acting as an electrode on one or both sides of a cation exchange membrane in place of the diaphragm and electrode described above.

Such a composite membrane is produced by: (1) impregnating a cation exchange membrane with a reducing agent such as NaBI (4, hydrazine, ethylenediamine, sodium hypophosphite, etc.), and then impregnating it with Pt, Rh, Ru, Pa,
A method of depositing the metal or its oxide on both sides of the membrane by immersing it in an aqueous solution of a water-soluble metal salt such as Ni or Cu, preferably a chloride, or (2) depositing the metal or its oxide on one side via a cation exchange membrane. It can be prepared by preparing an aqueous solution of various metal salts on the other side, and depositing the metal or its oxide on the surface of the membrane on the metal salt aqueous solution side by permeation of the reducing agent from the back side of the membrane.

This composite membrane uses a metal salt or metal oxide layer formed on the membrane as an electrode to carry out an electrolytic reaction within an ion exchange membrane, and is characterized by a low electrolytic voltage, making it particularly suitable for industrial mass production. ing.

The quaternary ammonium salt supplied as an aqueous solution to the anode chamber of the electrolytic cell has the general formula represents an alkyl group, an alkoxyalkyl group having 2 to 10 carbon atoms, an aryl group or a hydroxyaryl group, and X represents an acid group.

As specific examples, R1-R4 in the formula are methyl, ethyl,
Propyl, methyl, means methyl, hexyl, heptyl, octyl, nonyl, decyl groups and their hydroxy derivatives; methyl, ethyl, propyl, methyl or R-methyl groups substituted with methoxy, ethoxy, propoxy or butoxy groups; phenyl, benzyl , represents a phenethyl group and a group in which the benzene ring in these groups is substituted with a hydroxy group, and the acid group (anion)
O3-.

Examples include those representing BF4- and PF6-, such as tetramethylammonium chloride, tetramethylammonium chloride 9, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium sulfate, trimethylethanolammonium chloride, trimethylmethoxyammonium chloride P, dimethyl Dimethoxyammonium chloride, dimethylgetanolammonium chloride, methyltriethanolammonium chloride, tetraethanolammonium chloride, benzylmethyljetanolammonium chloride, phenyltrimethylammonium chlorite, phenyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyldimethylphenyl Examples include ammonium chloride.

These quaternary ammonium salts are used in aqueous solutions of 10 to 50 weight percent. If it is less than 10% by weight, the current flow rate will be poor, and if it exceeds 50% by weight, crystals of quaternary ammonium salt may precipitate, so it is not preferred.

In addition, in the electrolytic reaction, the liquid temperature should be kept below 50C. If the temperature exceeds 50C, the corrosivity of the anolyte increases, and the target substance decomposes in the catholyte, producing smoke with an ammonia odor, which is not preferable.

In addition, water is supplied to the cathode chamber to start the electrolytic reaction, but in order to increase the current efficiency, a small amount of the target product 4
It is preferable to add ammonium hydroxide in advance. Note that when using a composite membrane with electrode layers on both sides or a composite membrane with only a cathode layer, it is only necessary to supply pure water to the cathode chamber (°C).

During electrolysis, a DC voltage is applied at a current density of 1 to 100 A/dyx", preferably 10 to 50 A/+ai2. Under these electrolytic conditions, the cathode chamber force) also increases
Ammonium hydroxide aqueous solutions can be obtained in product concentrations of 1 to 40% by weight.

The electrodialysis that follows electrolysis is electrodialysis, which has a dialysis tank separated by a cation exchange membrane and an anion exchange membrane, has at least three dialysis chambers, and has a cathode chamber and an anode chamber at both ends. It is carried out using a tank. The materials forming the anode and cathode are the same as those for the electrolytic cell. A plurality of cation exchange membranes and anion exchange membranes can be disposed in the dialysis tank, but in this case, the positive and negative membranes are alternately disposed. The material for forming the exchange membrane is not particularly limited and may be any commonly used material.

The quaternary ammonium hydroxide aqueous solution taken out from the electrolytic tank was added to the above dialysis tank at a liquid temperature of 50C or less and a flow rate of 0.1 to 0.3y.
n/sec, current density 1 to 50 A/dyz
2. If a DC voltage is preferably applied at 1 to 20 A/dm2, impurities will quickly move to the anode chamber and the cathode chamber,
The desired quaternary ammonium hydroxide aqueous solution is obtained with high purity.

According to the production method of the present invention, alkali metals derived from raw materials,
It is possible to obtain highly pure ammonium 47th hydroxide containing extremely small amounts of impurities such as alkaline earth metals and anions.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 A diaphragm (Nafion 315 (fluororesin cation exchange membrane) manufactured by Jison Co., Ltd.) was attached to the electrolytic cell, a platinum-coated electrode was used as the anode, a nickel plate was used as the cathode, and tetramethylammonium was used in the anode chamber. A 40% by weight aqueous solution of chloride and a 3% by weight aqueous solution of tetramethylammonium hydroxide were supplied to the cathode chamber at a temperature of 30°C and a flow rate of 0.2ml/sec, and a DC voltage was applied at 20 A/am20 conditions. A 25% by weight aqueous solution of tetramethylammonium hydroxide was obtained at an electrolysis voltage of 6.5 to 12V and a current efficiency of 81%.

Next, Selemion GMV (styrene-divinylbenzene copolymer membrane manufactured by Asahi Glass Co., Ltd.) was used as the cation exchange membrane, Selemion AMV (styrene-divinyl inzene copolymer membrane manufactured by Asahi Glass Co., Ltd.) was used as the cathode ion exchange membrane, and the anode and The above 25% aqueous solution of tetramethylammonium hydroxide was supplied at a flow rate of Q, 1 m/ip, and a liquid temperature of 30C to an electrodialysis tank having three dialysis chambers using a platinum-coated electrode as a cathode. A DC voltage was applied at a current density of 10 A/di2. The fourth in the electrodialyzed solution obtained
The concentration of tetramethylammonium hydroxide was 18.3% by weight, and the metal content iY was as follows.

Na O,060”?/I K O,040 Ca <o, oi Mg <0.005 Fe <0.01 Cu <0.004 Pb O,001 Z n 0.001 Example 2 Tetramethyl in Example 1 A 23% by weight aqueous solution of tetraethylammonium hydroxide was obtained by electrolytic treatment in the same manner, except that a 40% by weight aqueous solution of tetraethylammonium chloride was used instead of the 40% by weight aqueous solution of ammonium chloride.

This aqueous solution was electrodialyzed under the same conditions as in Example 1 to obtain a 18.2 weight percent aqueous solution of tetraethylammonium hydroxide. The metal content in this treatment solution was as follows.

Na O,0707n9/I K O,040 Ca <0.01 Mg <0.005 Fe <o, o 1 cu <0.004 Pb O,002 Zn o-oo2 Comparative example Same electrolysis as in Example 1 A 25% by weight aqueous solution of tetramethylammonium hydroxide was obtained. The metal content of this product was measured without electrodialysis treatment. The results are as follows: 17 points.

Na O, 243m9/I K, 0.103 Ca O,050 Mg O,005 F e O,030 Cu <0.004 Pb o-oo3 Z　n　　　　　　　　　　　　　O,004 471

Claims (1)

[Claims] A high purity quaternary ammonium salt aqueous solution is electrolyzed using an electrolytic cell having a diaphragm or a composite membrane to obtain an aqueous solution of quaternary ammonium hydroxide, and then this aqueous solution is subjected to ion exchange membrane electrodialysis. A method for producing tetraammonium hydroxide.