Method for producing halogenated oxygen acids and apparatus for producing them

Abstract

Provided are a method and a device for efficiently producing a halogen oxyacid solution that has good quality and is industrially superior. Specifically, provided are a method and a device for producing halogen oxyacid, the method comprising a step for continuously supplying an organic alkali solution and a halogen from one end to the other end of a reaction tube, causing a liquid phase part and a gas phase part to alternately and repeatedly exist in a transfer passage of the reaction tube, and causing gas-liquid mixing to occur to the halogen and the organic alkali solution in the liquid phase part and / or the gas phase part.

Description

Technical Field

[0001] The present invention relates to a method for producing an industrially excellent halogen oxyacid solution by simultaneously supplying an organic alkali solution and a halogen into a reaction tube, gas-liquid mixing and dissolving them in the tube.

Background Art

[0002] Conventionally, various forms have been tried as methods for achieving a target treatment by mixing a gas that is soluble in a target liquid. For example, there is a method (Patent Document 1) of obtaining a liquid with a predetermined concentration by circulating a liquid in a tank and absorbing a gas. For the purpose of performing this more efficiently, it is also known that a tubular form is taken without using a tank as an apparatus. For example, generation of ozone water by blowing ozone into flowing water (Patent Document 2), or neutralization treatment by blowing carbon dioxide into alkaline wastewater (Patent Document 3), etc. can be mentioned.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] The gas dissolution methods described above are acceptable as long as the amount of gas used is within the range that can be completely dissolved in the liquid. However, all of these methods have drawbacks when dissolving large volumes of gas in a liquid. Specifically, if a gas with low solubility in the target liquid is used, undissolved gas leaks out of the system, resulting in the waste of more gas than necessary. If gases with a high environmental impact, such as ozone or halogens, leak out of the system, measures must be taken to prevent leakage and neutralize the harmful effects. For example, one method is to increase the contact time and frequency between the gas and the liquid in order to improve the solubility of the gas in the liquid. However, this requires increasing the volume of the equipment or installing a line mixer for stirring during the process. All of these methods result in larger and more complex equipment, which in turn increases costs and impacts quality.

[0005] Therefore, the present invention focuses on the solubility of halogens in organic alkaline solutions and has achieved a method of dissolving them by gas-liquid mixing in a tube without using a line mixer. This invention allows for a simpler and more efficient apparatus with less unreacted halogen, and provides an industrially superior method and apparatus for producing halogenated oxygen acid solutions. [Means for solving the problem]

[0006] As a result of extensive research to achieve the above objective, the inventors have discovered a method and apparatus for industrially producing halogenated oxygen acids more stably and efficiently by continuously supplying an organic alkaline solution and a halogen from one end of a reaction tube to the other, and by repeatedly alternating between a liquid phase and a gas phase within the transfer passage of the reaction tube, thereby mixing the organic alkaline solution and the halogen in the liquid and / or gas phases. This has led to the completion of the present invention.

[0007] In other words, the configuration of the present invention is as follows. Item 1 A method for producing halogenated oxygen acid, comprising the steps of continuously supplying an organic alkaline solution and a halogen from one end of a reaction tube to the other, repeatedly alternating between a liquid phase and a gas phase within the transfer passage of the reaction tube, and mixing the organic alkaline solution and the halogen in the liquid phase and / or gas phase. Item 2: The method for producing halogenated oxygen acid according to Item 1, wherein the ratio of the volume flow rate of halogen to the volume flow rate of organic alkaline solution supplied to the reaction tube is 1 to 50. Item 3 The method for producing halogen oxygen acid according to Item 1 or 2, wherein the reaction tube extends axially while rotating around an axis in the direction in which it extends from one end to the other. Item 4 A method for producing a halogenated oxygen acid according to any one of items 1 to 3, wherein the reaction tube is arranged to extend substantially horizontally. Item 5 The method for producing halogenated oxygen acid according to any one of Items 1 to 4, wherein the reaction tube is a reaction tube formed in a spiral shape with the axis extending from one end to the other as the helical axis. Item 6: A method for producing a halogenated oxygen acid according to any one of items 1 to 5, wherein the reaction tube is a reaction tube containing a fluororesin. Item 7: A method for producing halogenated oxygen acid according to any one of items 1 to 6, wherein the average inner diameter of the reaction tube is 5 mm or more. Item 8 A apparatus for producing halogenated oxygen acids, comprising a reaction tube that extends axially while rotating around an axis in which it extends from one end to the other, wherein the reaction tube is arranged such that the axis extends substantially horizontally, and an organic alkaline solution and a halogen are continuously supplied from one end to the other, and a liquid phase and a gas phase are repeatedly and alternately present in the transfer passage of the reaction tube, and the organic alkaline solution and the halogen are mixed in a gas-liquid mixture in the liquid phase and / or gas phase. Item 9 The apparatus for producing halogenated oxygen acid according to Item 8, further comprising means for supplying an organic alkaline solution and a halogen to the reaction tube in a ratio such that the ratio of the volume flow rate of the halogen to the volume flow rate of the organic alkaline solution is 1 to 50. Item 10 The apparatus for producing halogenated oxygen acids according to item 8 or 9, wherein the reaction tube is a spirally formed reaction tube, and the spiral axis of the reaction tube is arranged to extend substantially horizontally. Item 11 The apparatus for producing halogenated oxygen acids according to any one of items 8 to 10, wherein the reaction tube is a reaction tube containing fluororesin. Item 12 The apparatus for producing halogenated oxygen acids according to any one of items 8 to 11, wherein the average inner diameter of the reaction tube is 5 mm or more. Item 13 The apparatus for producing halogenated oxygen acids according to any one of items 8 to 12, wherein the reaction tube is configured such that the liquid residence time of the organic alkaline solution is from 5 seconds to 30 minutes. [Effects of the Invention]

[0008] An organic alkaline solution and halogen are continuously supplied from one end of the reaction tube, while the reaction solution containing the generated halogen oxyacid is continuously withdrawn from the other end. Frequent gas-liquid mixing occurs in the mixture within the reaction tube, maintaining a constant concentration and pH of the organic alkaline solution and the generated halogen oxyacid in a steady state. This suppresses side reactions, resulting in a reaction solution with good storage stability, and reduces waste of raw materials by minimizing unreacted halogen. Furthermore, the time required to obtain a reaction solution with a stable composition from the start of the reaction is shortened, reducing wastewater generation and enabling efficient and stable production of halogen oxyacid. The continuous supply of raw materials and continuous withdrawal of reaction products also enable large-scale industrial production. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing one embodiment of a manufacturing apparatus according to an embodiment of the present invention. [Figure 2] This figure shows the relationship between operating time and effective chlorine concentration when using the manufacturing method according to the embodiments and comparative examples of the present invention. [Figure 3]This is a schematic diagram showing the state of the gas phase and liquid phase within a reaction tube. (a) shows a state in which the liquid phase and gas phase alternate within the reaction tube, and (b) shows a state in which the liquid phase and gas phase do not alternate within the reaction tube. [Modes for carrying out the invention]

[0010] <Method for producing halogenated oxygen acids> (Reaction format, reaction tube) Next, one of the features of this embodiment is the use of a system in which an organic alkaline solution and halogen are continuously supplied, and the reaction solution containing the generated halogen oxyacid is continuously withdrawn. It is preferable that the continuous withdrawal of the reaction solution containing the halogen oxyacid is carried out in an amount corresponding to the amount of organic alkaline solution and halogen continuously supplied. "Corresponding amount" means an amount equal to or proportional to the total amount of organic alkaline solution and halogen supplied (total amount of organic alkali and halogen > amount withdrawn: both in volume). The same applies to the manufacturing apparatus described later.

[0011] In the present invention, it is preferable to keep the amount of organic alkaline solution and the amount of halogenated oxygen acid produced, which are components in the reaction tube under steady state, and the pH of the reaction solution taken out of the reaction tube constant, and it is preferable to precisely adjust the supply amount. In conventional semi-batch reaction methods, halogens are added to an organic alkaline solution in the reactor. As a result, the pH of the reaction solution tends to be high in the initial stages of the reaction, and decomposition of halogen oxyacids is more likely to occur at high pH levels. Furthermore, in halogen oxyacids generated in the high pH range, decomposition products are produced, posing a challenge to storage stability. On the other hand, by continuously supplying the organic alkaline solution and halogens, and continuously withdrawing the reaction solution, the reaction solution in the reaction tube reaches a steady state after a certain period of time, and the pH is maintained at a constant level. Therefore, decomposition of halogen oxyacids is suppressed once the system has stabilized.

[0012] According to the manufacturing method according to an embodiment of the present invention, it is possible to prevent the pH of the reaction solution from remaining high. In the present invention, the pH is the value at 25°C unless otherwise specified. Thus, by adopting a format in which an organic alkali solution and a halogen are continuously supplied and the reaction solution containing the generated halogen oxyacid is continuously taken out, it is possible to reduce the residence time at high pH that causes the largest side reaction of this reaction. As an example of the halogen used, when chlorine gas or chlorine is used, as a result, the chlorine yield can be maintained high. The chlorine yield here can be obtained from the ratio (%) of the number of moles of hypochlorite ions generated to the number of moles of chlorine molecules supplied into the organic alkali solution. When all the chlorine added to the organic alkali solution has reacted (no decomposition has occurred), the chlorine yield is 100%. When hypochlorite ions decompose during the reaction, the chlorine yield decreases. In the present invention, the reaction tube means a device in which a chemical reaction occurs during the manufacturing process of a chemical substance. It is preferable that the continuous supply of the organic alkali solution and the halogen into the reaction tube is performed at a constant ratio. Supplying at a constant ratio means that the supply rate is constant. Also, the continuous withdrawal of the reaction solution does not have to start simultaneously with the start of the implementation of the manufacturing method according to the embodiment of the present invention, and it may be performed after the pH of the reaction solution withdrawn from the reaction tube becomes constant.

[0013] In addition, it is a preferred embodiment to make the components in the reaction tube and the pH of the reaction solution uniform. In the reaction tube, it is preferable that the pH of the reaction solution of the supplied organic alkali solution and halogen is 10.5 to 14.5. More preferably, the pH of the reaction solution of the organic alkali solution and the halogen is 10.5 to 13.8. Even more preferably, the pH of the reaction solution of the organic alkali solution and the halogen is 12.0 to 13.8. Also, the pH of the reaction solution taken out from the reaction tube is preferably 12.0 to 13.8.

[0014] In order to mix an organic alkali solution and a halogen in a reaction tube, it is preferable to alternately and repeatedly have a liquid phase part and a gas phase part in a transfer passage in the transfer direction. Thereby, the liquid can be uniformly stirred and mixed without installing a line mixer for the mixing operation in the tube. Usually, as a stirring method for making the fluid passing through the tube uniform, a line mixer (stirring mixer) is adopted. The line mixer mainly includes those that drive a stirring blade installed in the space inside the tube to mix the fluid, or an in-line mixer (static mixing stirrer) without a driving part that performs mixing when the fluid passes through an element fixed in the space inside the tube. These line mixers are used to efficiently perform fluid mixing. However, when it is necessary to generate a high-purity liquid that does not prefer contamination such as particles and metal components like a semiconductor chemical solution, contamination from the liquid contact part greatly affects the quality, so it may be difficult to install a line mixer in the tube. In a reaction tube without a line mixer installed, since the gas-liquid miscibility drops, a reaction liquid with non-uniform concentration and a short path in the gas phase part will occur in the tube, which is disadvantageous as an industrial manufacturing method.

[0015] In the transfer passage of the reaction tube, a state where the liquid phase part and the gas phase part do not alternately and repeatedly exist in the transfer direction leads to a decrease in the number and frequency of gas-liquid contacts, resulting in deterioration of the gas-liquid mixing state in the tube. In this case, in order to stabilize the liquid composition, it is necessary to add a process to improve the gas-liquid mixing state. When a line mixer is not installed in the tube, the length of the reaction tube must be extended. Increasing the length of the reaction tube leads to an increase in equipment costs and an increase in the amount of waste liquid generated when replacing the inside of the reaction tube, which is disadvantageous in terms of both equipment and raw materials costs. Making the liquid phase part and the gas phase part alternately and repeatedly exist in the transfer passage of the reaction tube as in the present invention leads to subdividing the number and frequency of gas-liquid contacts in the reaction tube, creating a state close to a pseudo plug flow in the reaction tube, and making it possible to continuously obtain a reaction liquid with the same concentration. Thereby, the organic alkali solution and the halogen are uniformly mixed in the reaction tube, and the installation of a line mixer can be made unnecessary. These effects make the present invention particularly characterized by the fact that a stable liquid composition can be continuously obtained by replacing the reaction solution within the reaction tube only once. In other words, the volume required for the state of the tube to be replaced from the organic alkaline solution before the reaction to the liquid after the reaction is determined by the length of the reaction tube from the inlet to the outlet. This optimizes the replacement operation within the tube by the reaction solution and minimizes the amount of waste liquid that is unnecessary from the start of the reaction until the liquid composition stabilizes, thus having an industrially advantageous effect.

[0016] The simplest method for alternating liquid and gas phases within a reaction tube is to make the diameter of the supply pipes that supply the gas and liquid phases the same as or less than the diameter of the reaction tube. This makes it possible to alternately create gas and liquid phases of the same diameter as the reaction tube at the inlet side of the reaction tube where the gas and liquid come into contact. However, if the liquid-gas ratio (the value obtained by dividing the volume flow rate of the gas phase supplied to the reaction tube per unit time by the volume flow rate of the liquid phase supplied to the reaction tube per unit time) is 1 or more, the halogen present in the gas phase will not dissolve sufficiently in the liquid phase and will be discharged from the outlet side of the reaction tube as undissolved halogen. As a countermeasure, one method is to extend the length of the reaction tube to increase the time it takes for the halogen to dissolve, but as a simpler method to promote the dissolution of halogen in the reaction tube, it is preferable to extend the tube while rotating it with respect to the axial direction in which the reaction tube extends. That is, it is preferable to extend the reaction tube axially while rotating it around an axis that is the direction in which the reaction tube extends from one end to the other. The axial direction mentioned here is preferably horizontal rather than vertical, but this does not limit the axis to the horizontal direction. The direction of the extending axis may have some inclination, and among inclined axial directions, it is more preferable to extend the reaction tube in a substantially horizontal direction.

[0017] The diameter of rotation required for axial rotation can be determined according to the length of the reaction tube and the strength of the material used. For example, it can be between 30 mm and 3000 mm, and preferably between 60 mm and 600 mm. By forming a rotation of one or more revolutions in the reaction tube, the mixing efficiency of the gas and liquid is improved. In the reaction tube, the gas phase rises due to buoyancy generated according to the volume of the gas, and the liquid phase descends due to gravity. However, by rotating the reaction tube, the gas phase is guaranteed to come into contact with the liquid phase accumulated at the bottom in the vertical direction at least once. Therefore, the more revolutions the reaction tube rotates, the more advantageous it is for mixing the gas and liquid, and the less likely the gas phase is to short-circuit. Note that the gas phase may not be present at the bottom in the vertical direction of the reaction tube. Also, the lengths of the gas phase and liquid phase in the direction of transport within the reaction tube may be uneven. There is no upper limit to the number of rotations of the swirling reaction tube, but formation by 2 rotations or more is preferable, more preferably 5 rotations or more, and even more preferably 10 rotations or more. On the other hand, the upper limit to the number of rotations is usually 50 rotations or less. Also, there is no upper limit to the range of the average inner diameter of the reaction tube, but it is preferably 5 mm or more, more preferably 5 mm to 500 mm, and even more preferably 10 mm to 100 mm. The appearance of the apparatus that satisfies these configurations is most preferably such that the reaction tube is formed in a spiral shape along the axial direction, but the shape of the reaction tube is not limited to this, and it is also preferable that the reaction tube is bent alternately along the axial direction, or that it is processed in a wavy shape along the axial direction. The inner diameter and length of the reaction tube affect the volume of the reaction solution, making them important factors for the large-scale industrial production of the reaction solution. The large-scale industrial production referred to here means efficiently and continuously producing the target reaction solution while reducing the amount of waste liquid generated. Preferably, the production volume is equal to or greater than the volume of liquid occupying the tube volume per hour, more preferably five times or more, and even more preferably 100 times or more.

[0018] In addition to the organic alkaline solution and halogen continuously supplied into the reaction tube, an inert gas may also be supplied to the reaction tube. The supply of an inert gas creates alternating periods of liquid and gas phases within the reaction tube and is also useful in preventing backflow between the liquid and gas phases within the system. An inert gas refers to a stable gas unrelated to the reaction, such as air, nitrogen, argon, or helium, and air is preferred from a cost standpoint. However, since carbon dioxide contained in the air can dissolve in the reaction solution, causing a decrease in pH, or react and generate impurities, it is more preferable to use a highly purified inert gas, and among these, nitrogen is preferred from a cost standpoint. The volume inside the reaction tube can be changed according to the supply rate of the organic alkaline solution used. If the liquid residence time is defined as the value obtained by dividing the volume inside the reaction tube by the volume of organic alkaline solution supplied to the reaction tube per unit time, then a volume inside the reaction tube that results in a liquid residence time of 5 seconds to 30 minutes is preferable, and more preferably 10 seconds to 5 minutes. In this invention, a liquid with a stable composition can be continuously obtained by replacing the reaction solution inside the reaction tube only once. This means that the time required to obtain a stable liquid composition is directly related to the liquid residence time. If the mixing state inside the tube is insufficient at the start of the reaction, at least three times the liquid residence time is required to obtain a liquid with a stable composition. Furthermore, the supply rate of the halogen is preferably 1 to 50, more preferably 10 to 30, in terms of the ratio of the volume flow rate of halogen to the volume flow rate of the organic alkaline solution supplied to the reaction tube. Within this range, even if the shape of the reaction tube is not the one described above, in which the tube is extended while spiraling with respect to the axial direction in which the reaction tube extends, it can contribute to realizing a configuration in which gas phase and liquid phase alternately exist in the direction of transfer within the reaction tube. The volumetric flow rate of the halogen supplied to the reaction tube is calculated at 0°C and 1 atm when the halogen is a gas. By dissolving the halogen supplied into the reaction tube in the organic alkaline solution, dissolved gases in the solution can be degassed. Specifically, the halogen generates heat of dissolution in the reaction tube, raising the solution temperature, and the dissolved gases that can no longer dissolve in the solution move out of the solution, resulting in degassing. As the liquid-gas ratio increases, the heat of dissolution increases in proportion to the amount of halogen supplied, making it easier to obtain the degassing effect. Dissolved gases include nitrogen, oxygen, and carbon dioxide, but the dissolved gases to be degassed are not limited to these. Furthermore, while there are also cylindrical reaction tubes, this refers to a state where only one opening of the reaction tube is closed. Cylindrical reaction tubes are structurally unsuitable for obtaining a liquid with a stable composition in a short time, which is the effect of the present invention. In other words, the reaction tube must have separate sections for the flow of liquid, and liquid displacement within the reaction tube is difficult, making it difficult to stabilize the liquid composition. Therefore, the liquid must be discarded until it stabilizes, and the present invention, which achieves stability with a single liquid displacement, is economically advantageous because it also reduces the amount of waste liquid generated.

[0019] (Organic alkaline solution) The organic alkali solution supplied to the reaction tube may be either an aqueous solution in which the organic alkali is dissolved in water or a solution in which the organic alkali is dissolved in a non-aqueous solvent. The organic alkali solution can be obtained by dissolving the organic alkali in water or a non-aqueous solvent, or by diluting a commercially available organic alkali solution to a desired concentration. Among these water and non-aqueous solvents, water is preferred because it is readily available industrially and allows for the acquisition of a high-purity organic alkali solution. Examples of non-aqueous solvents include known organic solvents that can dissolve organic alkalis. Specifically, alcohols and glycols are examples, with methanol and propylene glycol being particularly preferred. The concentration of the organic alkali solution is not particularly limited, but if the concentration of the organic alkali becomes high, salts will precipitate and become solid. Therefore, the concentration of the organic alkali in the organic alkali solution is preferably 0.01 to 30% by mass, more preferably 0.05 to 27.5% by mass, and even more preferably 0.1 to 25% by mass.

[0020] As a solvent for organic alkaline solutions, an aqueous solution using only water may be used, or it may be mixed with an organic solvent to form a non-aqueous solution, or an aqueous solution may be mixed with an organic solvent. The solvent should be appropriately changed depending on the application of the solution containing halogenated oxygen acids. For example, when the object to be cleaned is ruthenium, sufficient cleaning can be achieved with water alone, so an organic alkaline aqueous solution can be used. In this embodiment, the organic alkali solution is preferably a solution of onium hydroxide. Examples of onium hydroxide include one or more selected from the group consisting of ammonium hydroxide, phosphonium hydroxide, sulfonium hydroxide, iminium hydroxide containing multiple bonds, and diazonium hydroxide. Among these, a solution of ammonium hydroxide, which contains many relatively stable compounds, is more preferable. Furthermore, the above-mentioned solution of onium hydroxide is preferably an aqueous solution of onium hydroxide. Furthermore, the above-mentioned solution of ammonium hydroxide is preferably a solution of quaternary alkylammonium hydroxide.

[0021] The quaternary alkylammonium hydroxide solution is preferably a solution of a quaternary alkylammonium hydroxide in which each alkyl group has 1 to 10 carbon atoms, and more preferably a solution of a quaternary alkylammonium hydroxide in which each alkyl group has 1 to 5 carbon atoms. Specific examples of quaternary alkylammonium hydroxides include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and choline. These quaternary alkylammonium hydroxides may be used individually or in combination of two or more. Furthermore, the four alkyl groups contained in the quaternary alkylammonium hydroxide may have the same number of carbon atoms or may have different numbers of carbon atoms. Furthermore, the various conditions described above and below, such as the concentration range of the organic alkali in the organic alkali solution supplied to the reactor, the pH range of the organic alkali solution, and the concentration range of the organic alkali in the reaction solution, are applicable regardless of which of the above specific examples of organic alkali is used.

[0022] The organic alkali solution may contain chemical species other than organic alkalis. Examples of such chemical species include halides and organic substances containing halogens, and more specifically, tetraalkylammonium halides such as tetramethylammonium bromide, but are not limited to these. Furthermore, the organic alkali solution may be obtained by first reacting with a halogen and then using the reaction solution again, and the same halogen or a different halogen may be supplied to the solution.

[0023] (A process of mixing an organic alkaline solution with a halogen in a gas-liquid mixture to produce a reaction solution containing a halogen oxygen acid.) In the process of producing a reaction solution containing halogenated oxygen acid by mixing an organic alkaline solution and a halogen in a gas-liquid mixture and reacting them, the pH of the reaction solution containing the halogenated oxygen acid produced in the reaction tube tends to decrease. In this embodiment, the lower limit of the pH of the raw material organic alkaline solution is 10.5 or higher, preferably 11.0 or higher, more preferably 11.5 or higher, and particularly preferably above 12.0. The upper limit of the pH of the organic alkaline solution is determined by the concentration of the organic alkali. An example of the upper limit of the pH of the organic alkaline solution is 14.5 or lower. Furthermore, the organic alkali solution used in this embodiment preferably contains 0.01 ppb to 20 ppb of each metal, specifically sodium, potassium, aluminum, magnesium, iron, nickel, copper, silver, cadmium, and lead. Of course, the metal content in the organic alkali solution used may be less than 0.01 ppb, but obtaining such an organic alkali solution is difficult. Therefore, by using an organic alkaline solution in which the content of the above metal satisfies the above range, it becomes easy to obtain the solution itself, and it becomes easy to remove or reduce the metal impurities during and after the production of the reaction solution containing the halogenated oxygen acid. Furthermore, since the above-mentioned metals dissolve from the areas in contact with the organic alkaline solution within the reaction tube, it is preferable to use a reaction tube with a small wetted surface area. In other words, a reaction tube with a small volume is an important factor in reducing impurities and is very effective from the standpoint of quality control. There is no upper limit to the wetted surface area of ​​the reaction tube, but a suitable wetted surface area is 0.01 m². 2 More than 10m 2 The following, and more preferably 0.1m 2 Above 1.0m 2 The following applies:

[0024] The organic alkaline solutions described above can be commercially available. In particular, organic alkaline solutions used as photoresist developers for semiconductor devices, which have been purified by electrolysis and / or contact with ion exchange resins, etc., are preferably used. Furthermore, these commercially available solutions can be diluted with a solvent that does not contain metal impurities, such as ultrapure water, before use. In the manufacturing method according to the embodiment of the present invention, the supply rate of the organic alkaline solution used is preferably 33 mL / min to 12 L / min, and more preferably 0.2 L / min to 6 L / min, when the volume of the reaction tube is 1 L.

[0025] (A reaction that occurs when an organic alkaline solution is brought into contact with a halogen.) For example, when using quaternary alkylammonium hydroxide as an organic alkali, contacting and reacting its solution with a halogen causes the hydroxide ions of the quaternary alkylammonium hydroxide to be replaced by hypochlorite ions generated by the halogen, thereby producing a quaternary alkylammonium hypohalite solution. In this embodiment, the halogen used is not particularly limited and commercially available halogens can be used. Specific examples of halogens include chlorine, bromine, iodine, hypochlorous acid, hypobromous acid, hypoiodic acid, chlorous acid, bromous acid, iodic acid, chloric acid, bromate, or iodic acid. When using chlorine or bromine, their gases can be used. Among these, chlorine gas is preferred. Next, in this embodiment, a method of contacting a quaternary alkylammonium hydroxide solution as the organic alkali solution and chlorine gas as the halogen will be described as an example of an embodiment of the present invention. In the following description, unless otherwise specified, it may be assumed that a quaternary alkylammonium hydroxide solution is used as the organic alkali solution and chlorine gas is used as the halogen, but this is merely an example.

[0026] (pH of the liquid phase during the reaction) In this embodiment, the pH of the liquid phase during the reaction is preferably 10.5 or higher. In this embodiment, the liquid phase refers to the portion occupied by the reaction solution produced by mixing the quaternary alkylammonium hydroxide solution and chlorine gas during the reaction. There is no particular upper limit to the pH of the liquid phase, but if the pH during the reaction is excessively high, the hypochlorite ions may decompose and the effective chlorine concentration may decrease if the solution is stored at the same pH for a long period after the reaction is complete. Therefore, the pH of the liquid phase during the reaction is preferably 10.5 to 14.5, more preferably 10.5 to 13.8, and even more preferably 12 to 13.8. If the pH is within the above range, the decomposition of hypochlorite ions is suppressed during storage of the resulting quaternary alkylammonium hypochlorite solution, and the storage stability is improved.

[0027] (Reaction temperature) In the manufacturing method of this embodiment, the reaction temperature range is preferably -35°C to 45°C, more preferably -15°C to 40°C, and even more preferably -5°C to 35°C. When the reaction temperature is within the above range, the hydroxide organic alkali solution and halogen react sufficiently, and halogen oxygen acid can be obtained in high yield. If the reaction temperature is below -35°C, the organic alkali begins to solidify, and the reaction with halogen becomes insufficient. On the other hand, if the reaction temperature exceeds 45°C, the halogen oxygen acid ions generated in the halogen oxygen acid solution decompose due to heat. In particular, when the pH during the reaction is 13.8 or higher, the decomposition of halogen oxygen acid becomes more pronounced as the reaction temperature increases. The yield of halogen oxygen acid can be evaluated by the chlorine yield. As described above, according to the manufacturing method of this embodiment, halogen oxygen acid with excellent storage stability can be produced, for example, one that can maintain sufficient cleaning and removal power even after 10 days have passed since production. As is clear from this, the halogen oxygen acid obtained by the manufacturing method of this embodiment has excellent storage stability and can be suitably used in the manufacturing process of semiconductor devices.

[0028] (Material for the inner surface of the reaction tube) In this embodiment, a halogenated oxygen acid is produced by contacting the above-mentioned organic alkaline solution with the above-mentioned chlorine gas in a reaction tube. At this time, first, a predetermined amount of the organic alkaline solution is introduced into the reaction tube, and then the chlorine gas is introduced so as to come into contact with the organic alkaline solution. In this embodiment, the surface of the reaction tube that comes into contact with the organic alkaline solution (hereinafter sometimes simply referred to as the "inner surface of the reaction tube") is formed from general-purpose borosilicate glass or an organic polymer material. According to the inventors' studies, when a reaction tube made of general-purpose borosilicate glass (hereinafter referred to as "glass") is used as the reaction tube, metal components contained in the glass, such as sodium, potassium, and aluminum, dissolve slightly in the organic alkaline solution. This is thought to be due to the fact that the organic alkaline solution used as a raw material is alkaline. Therefore, more preferably, by forming the inner surface of the reaction tube with an organic polymer material, the inclusion of impurities containing the above-mentioned metals (metallic impurities) can be further reduced.

[0029] Furthermore, the reaction is preferably carried out in a light-shielded environment, and specifically, the reaction tube is preferably light-shielded inside. The chlorine gas present in the reaction tube may be excited by light and generate chlorine radicals. When chlorine radicals are generated, they may affect the organic alkaline solution and the halogenated oxygen acid produced in the reaction that are present in the reaction tube, causing decomposition. In addition, the halogenated oxygen acid itself may decompose when exposed to light, so it is preferable to shield the reaction tube, attached piping, etc. from light.

[0030] In this embodiment, when an organic solvent is used, it is preferable to make the reaction apparatus explosion-proof. Therefore, in order to have a simple apparatus configuration, it is preferable to use water as the solvent for the organic alkaline solution. In this embodiment, the organic polymer material used for the inner surface of the reaction tube can be vinyl chloride resin (flexible or rigid vinyl chloride resin), nylon resin, silicone resin, polyolefin resin (polyethylene, polypropylene), fluororesin, etc. Among these, fluororesin is preferred considering ease of molding, solvent resistance, and low elution of impurities. The fluororesin is not particularly limited as long as it is a resin (polymer) containing fluorine atoms, and known fluororesins can be used. Examples include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, chlorotrifluoroethylene-ethylene copolymer, and cyclized polymers of perfluoro(butenyl vinyl ether). Among these, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is preferred considering the ease of obtaining the reaction tube itself and productivity.

[0031] In this embodiment, methods for forming the inner surface of the reaction tube with an organic polymer material include forming the entire reaction tube with an organic polymer material, and covering only the inner surface of a glass or stainless steel reaction tube with an organic polymer material. Furthermore, the organic polymer material can be washed before use to prevent metal components from leaching out. Specifically, it is preferable to thoroughly wash it with an acid such as high-purity nitric acid or hydrochloric acid (for example, by immersing it in a solution with an acid concentration of 1 mol / L for 12 hours), and then wash it further with ultrapure water or the like. In addition, in order to ensure a stable reaction, it is preferable to wash the inner surface of the reactor formed from the organic polymer material using the above method before reacting the organic alkaline solution with chlorine gas.

[0032] In this embodiment, if the surface in the reaction tube that comes into contact with the organic alkaline solution is formed of an organic polymer material, the other parts may be glass, stainless steel, or passivated stainless steel. In this embodiment, the organic alkaline solution and chlorine gas are brought into contact in a reaction tube, and the reaction temperature range is not particularly limited, but it is preferable to use the same temperature as described above. Furthermore, if carbon dioxide is present in the reaction system, the pH of the resulting halogenated oxygen acid solution tends to decrease. Therefore, considering stable production, it is preferable to keep carbon dioxide out of the reaction system. Specifically, it is preferable to use an organic alkaline solution, chlorine gas, etc., with reduced carbon dioxide content. It is also preferable to carry out the reaction in the presence of an inert gas with reduced carbon dioxide content (for example, in the presence of nitrogen gas). By reacting under these conditions, the decrease in pH of the resulting halogenated oxygen acid solution can be suppressed, thereby improving storage stability.

[0033] <Equipment for producing halogenated oxygen acids> Next, an embodiment of the apparatus for producing halogenated oxygen acids will be described. The above production method can be carried out using the production apparatus of this embodiment. As an example of the production apparatus according to this embodiment, a case in which a quaternary alkylammonium hydroxide solution is used as the organic alkali and chlorine gas is used as the halogen is given. The conditions such as the type and concentration of the organic alkali and halogen supplied as raw materials can be the same as those described in the above-described method for producing halogenated oxygen acids. The manufacturing apparatus of this embodiment includes a reaction tube that extends axially while rotating around an axis that extends from one end to the other, the reaction tube being arranged so that the axis extends substantially horizontally, and an organic alkaline solution and a halogen are continuously supplied from one end to the other, and a liquid phase and a gas phase are repeatedly and alternately present in the transfer passage of the reaction tube, and the organic alkaline solution and halogen are mixed in a gas-liquid mixture in the liquid phase and / or gas phase. Figure 1 shows a schematic diagram of the manufacturing apparatus according to this embodiment. The manufacturing apparatus described in Figure 1 comprises a reaction tube 1, a supply pipe 2 for a quaternary alkylammonium hydroxide solution as a means of supplying organic alkali to the reaction tube, a pipe valve 5 for operating the liquid supply and stopping operations, a chlorine gas supply pipe 3 as a means of supplying halogen, a pipe valve 6 for operating the chlorine gas supply and stopping operations, and a reaction liquid extraction pipe 8 as a means of extracting the reaction liquid from the reaction tube to the outside. In reaction tube 1, the quaternary alkylammonium hydroxide solution to be supplied is supplied from the quaternary alkylammonium hydroxide solution supply pipe 2, and the chlorine gas to be supplied is supplied from the chlorine gas supply pipe 3, both of which are supplied continuously. The supply and cessation of chlorine gas are performed using the pipe valve 6. The resulting reaction solution is continuously removed from the reaction solution removal pipe 8. For the parts in contact with the quaternary alkylammonium hydroxide solution that flow through them, the conditions described in the above manufacturing method can be used as is. The inner surface of reaction tube 1 is preferably made of an organic polymer material. Specifically, the reaction tube is preferably a reaction tube containing fluororesin, and it is preferable that all or at least the inner surface of reaction tube 1 is made of fluororesin. The fluororesin may be any of the materials exemplified in "Material for the inner surface of the reaction tube" above.

[0034] As a means of supplying chlorine gas, it is preferable that the diameters of the chlorine supply pipe 3 and the reaction pipe 1 be the same. However, in order to facilitate the dispersion of chlorine gas into the liquid phase, the diameter of the chlorine gas supply pipe 3 may be smaller than the diameter of the reaction pipe 1. The chlorine gas blowing velocity is preferably 0.1 m / sec to 10 m / sec at 0°C and 1 atm. The volume inside the reaction tube can be varied according to the supply rate of the quaternary alkylammonium hydroxide solution used. If the liquid residence time is defined as the volume of the reaction tube divided by the volume of the quaternary alkylammonium hydroxide solution supplied to the reaction tube per unit time, then a volume of the reaction tube that results in a liquid residence time of quaternary alkylammonium hydroxide solution of preferably 5 seconds to 30 minutes is preferred, and more preferably 10 seconds to 5 minutes. Furthermore, the supply rate of the halogen supplied is preferably 1 to 50, and more preferably 10 to 30, in terms of the ratio of the volume flow rate of halogen to the volume flow rate of organic alkali solution supplied to the reaction tube.

[0035] The reaction tube is preferably arranged to extend axially, rotating around an axis that runs from one end to the other. It is also preferable that the reaction tube extends substantially horizontally, and even more preferable that the reaction tube is spirally formed and that its spiral axis extends substantially horizontally. The required rotational diameter (inner diameter of the spiral) can be determined according to the length of the reaction tube and the strength of the material used, for example, between 30 mm and 3000 mm, and preferably between 60 mm and 600 mm. The reaction tube forming one or more rotations improves gas-liquid mixing. Therefore, there is no upper limit to the number of rotations of the spiraling reaction tube, but it is preferable to form the device with at least two rotations, more preferably five or more, and even more preferably ten or more. On the other hand, the upper limit of the rotational number is usually 50 or less. A higher number of rotations of the reaction tube is advantageous for gas-liquid mixing. There is no upper limit to the average inner diameter range of the reaction tube, but it is preferably 5 mm or more, more preferably 5 mm to 500 mm, and even more preferably 10 mm to 100 mm.

[0036] The reaction tube 1 may be equipped with a nitrogen gas supply pipe 4 as a means for supplying nitrogen into the reaction tube 1 in order to adjust the concentration of the gas components supplied to the reaction tube 1. A pipe valve 7 may also be provided for operating the supply and stopping of nitrogen gas. The reaction between the quaternary alkylammonium hydroxide solution and chlorine is an exothermic reaction. In the manufacturing apparatus according to this embodiment, the temperature inside the reaction tube 1 can be measured, for example, using a reaction solution temperature measuring device 9 as a means for measuring the temperature in the reaction tube 1. Furthermore, the manufacturing apparatus according to this embodiment may be equipped with a reaction tube temperature control jacket 10 as a means for controlling the reaction temperature in the reaction tube, specifically as a means for removing heat from the reaction tube. Heat removal can be performed using this reaction tube temperature control jacket 10. The manufacturing storage according to this embodiment may be equipped with light-shielding means to carry out the reaction under light-shielding conditions. In addition, the manufacturing apparatus according to the present embodiment may include a reaction liquid pH measurement device 11 disposed in the reaction liquid extraction pipe 8 as a means for measuring the pH of the reaction liquid. Further, since the measurement liquid used for pH measurement may cause contamination of the reaction liquid, it is more preferable to branch and circulate the line. By using the reaction liquid pH measurement device 11, the pH of the reaction liquid after the reaction can be measured. The manufacturing apparatus according to the present embodiment preferably includes at least one of the reaction temperature measurement means, the reaction temperature control means, and the pH measurement means in the above reactor, more preferably includes two of them, and even more preferably includes all of them.

[0037] After the reaction liquid extraction pipe 8, decontamination means may be provided so that unreacted chlorine or the like is not discharged outside the system. Specifically, a caustic soda decontamination device 13 may be installed. As the configuration of the caustic soda decontamination device 13, for example, in a reaction liquid storage tank 12 that stores the reaction liquid sent through the reaction liquid extraction pipe 8, the gas contained in the reaction liquid generated in the gas phase part of the storage tank is transferred to the caustic soda decontamination device 13 through an exhaust gas pipe 14 connected to the storage tank and made to soak in a solution containing caustic soda. Further, an exhaust gas pipe 15 for discharging the detoxified gas may be provided in the gas phase part of the caustic soda decontamination device 13.

Examples

[0038] Next, the present invention will be described in detail using examples and comparative examples, but the present invention is not limited to the examples.

[0039] <pH measurement method> The pH of an aqueous solution of quaternary alkylammonium hydroxide and 30 mL of an aqueous solution of quaternary alkylammonium hypochlorite was measured using a desktop pH meter (LAQUA F-73, manufactured by Horiba, Ltd.). The pH measurement was carried out after stabilizing at 25°C.

[0040] <Method for calculating available chlorine concentration and hypochlorite ion concentration> Add 0.5 mL of the treatment solution (quaternary ammonium hypochlorite solution), 2 g of potassium iodide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., reagent grade), 8 mL of 10% by mass acetic acid, and 10 mL of ultrapure water to a 100 mL Erlenmeyer flask and stir until the solids dissolve to obtain a brown solution. The prepared brown solution is subjected to redox titration using a 0.02 M sodium thiosulfate solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., for volumetric analysis) until the solution changes color from brown to very pale yellow. Then, starch solution is added to obtain a pale purple solution. To this solution, a 0.02 M sodium thiosulfate solution was added, and the effective chlorine concentration was calculated using the point at which the solution became colorless and transparent as the endpoint. The hypochlorite ion concentration was also calculated from the obtained effective chlorine concentration. For example, if the effective chlorine concentration is 1% by mass, the hypochlorite ion concentration will be 0.73% by mass.

[0041] <Chlorine Yield> The chlorine yield was determined from the ratio (%) of moles of hypochlorite ions produced to moles of chlorine molecules supplied to the organic alkaline solution. If all the chlorine added to the organic alkaline solution reacted (no decomposition occurred), the chlorine yield was 100%. If hypochlorite ions decomposed during the reaction, the chlorine yield decreased.

[0042] <Method for evaluating storage stability> A quaternary alkylammonium hypochlorite solution was transferred to a glove bag. After the carbon dioxide concentration in the glove bag fell to 1 ppm or less, the solution was transferred to a PFA (perfluoroalkoxy fluoropolymer: tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) container and sealed. Next, after storage for 10 days in a light-shielded environment at 23°C, the hypochlorite ion concentration of the quaternary alkylammonium hypochlorite solution in the PFA container was measured. A hypochlorite ion concentration ratio (concentration after 10 days / initial concentration) of 80% to 100% was considered good, 60% to less than 80% was considered somewhat good, and less than 60% was considered poor.

[0043] <Example 1> A spiral reaction tube was formed by rotating a PFA (fluoropolymer) reaction tube (inner diameter 8 mm, length 1 m) six times around a 50 mm diameter axis, with the horizontal axis as the axis of rotation. This reaction tube was installed horizontally. Tetramethylammonium hydroxide solution (concentration 12.0 mass%, pH 14.1, liquid temperature 5°C) was supplied at 370 ml / min and chlorine at 209.8 mmol / min from the inlet side of the reaction tube. The reaction solution obtained from the outlet side of the reaction tube was discarded for 1 minute from the start of operation to replace the contents of the tube, and then continuously sampled for 5 minutes. The liquid residence time was 8 seconds, and gas and liquid phases alternated within the reaction tube in the direction of transfer. The amount of unreacted chlorine, calculated from the effective chlorine concentration in the sodium hydroxide solution (concentration 10 mass%, 1000 ml) prepared downstream of the reaction tube for chlorine leakage prevention, was equivalent to less than 100 mass ppm of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 3.9% by mass, pH 13.4, liquid temperature 17°C) was obtained. The chlorine yield was over 99%, and the storage stability was good. Furthermore, after the above sampling, continuous operation was carried out for 2 hours under the same conditions. The liquid composition of the sample obtained by sampling for 5 minutes 1 hour after the start of operation was an effective chlorine concentration of 3.9% by mass and a pH of 13.4, and the liquid composition of the sample obtained by sampling for 5 minutes 2 hours later was also an effective chlorine concentration of 3.9% by mass and a pH of 13.4. The production volume per hour was 23 L / H.

[0044] <Comparative Example 1> As a comparative example, an experimental example is shown in which the reaction tube in Example 1 is not modified. A reaction tube made of PFA (a fluoropolymer) with an inner diameter of 8 mm and a length of 1 m was extended into a straight tube and installed horizontally. When tetramethylammonium hydroxide solution (concentration 12.0 mass%, pH 14.1, liquid temperature 5°C) and chlorine were supplied from one end of the reaction tube at a rate of 370 ml / min and 209.8 mmol / min respectively, a short-circuit of chlorine gas occurred within the reaction tube, causing unstable liquid supply and a decrease in liquid supply to 140 ml / min. The liquid residence time was 22 seconds, and within the reaction tube, the gas phase and liquid phase were separated into upper and lower layers, and did not alternate in the direction of transfer (see Figure 3(b)). The reaction solution obtained from the outlet side of the reaction tube was continuously sampled for 2 minutes. The unreacted chlorine, calculated from the effective chlorine concentration in the sodium hydroxide solution (concentration 10 mass%, 1000 ml) prepared in the subsequent process to prevent chlorine leakage, corresponded to 50% of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 4.5% by mass, pH 11.0, liquid temperature 18°C) was obtained. The chlorine yield was 90%, and storage stability was poor.

[0045] <Example 2> A spiral reaction tube was formed by rotating a PFA (fluoropolymer) reaction tube (inner diameter 8 mm, length 1 m) three and a half times around a 100 mm diameter axis, with the horizontal axis as the axis of rotation. This reaction tube was then installed horizontally. Tetramethylammonium hydroxide solution (concentration 4.8 mass%, pH 13.7, liquid temperature 5°C) was supplied at 200 ml / min and chlorine at 12.5 mmol / min from the inlet side of the reaction tube. The reaction solution obtained from the outlet side of the reaction tube was discarded for 1 minute from the start of operation to replace the contents of the tube, and then continuously sampled for 5 minutes. The liquid residence time was 15 seconds, and gas and liquid phases alternated within the reaction tube in the direction of transfer. The amount of unreacted chlorine, calculated from the effective chlorine concentration in the sodium hydroxide solution (concentration 10 mass%, 1000 ml) prepared downstream of the reaction tube for chlorine leakage prevention, was equivalent to 500 mass ppm of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 0.4% by mass, pH 13.6, liquid temperature 6°C) was obtained. The chlorine yield was over 99%, and the storage stability was good.

[0046] <Example 3> This example shows an experimental case where the reaction tube in Example 2 was not modified. A reaction tube made of PFA (a fluoropolymer) with an inner diameter of 8 mm and a length of 1 m was extended into a straight tube and installed horizontally. A tetramethylammonium hydroxide solution (concentration 4.8% by mass, pH 13.7, liquid temperature 7°C) was supplied from one end of the reaction tube at a rate of 200 ml / min, and chlorine at a rate of 12.5 mmol / min. The reaction solution obtained from the outlet side of the reaction tube was discarded for 1 minute from the start of operation to replace the contents of the tube, and then continuously sampled for 5 minutes. The liquid residence time was 15 seconds, and gas and liquid phases alternated within the reaction tube in the direction of transfer (see Figure 3(a)). The unreacted chlorine, calculated from the effective chlorine concentration in the sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared downstream of the reaction tube for chlorine leakage prevention, was equivalent to 5% of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 0.4% by mass, pH 13.6, liquid temperature 8°C) was obtained. The chlorine yield was over 99%, and the storage stability was good.

[0047] <Example 4> A spiral reaction tube, identical to that used in Example 1, was installed horizontally. A tetramethylammonium hydroxide solution (concentration 25.0% by mass, pH 14.4, liquid temperature 6°C) was supplied at 75 ml / min, and chlorine at 75.9 mmol / min from the inlet side of the reaction tube. The reaction solution obtained from the outlet side of the reaction tube was discarded for 1 minute from the start of operation to replace the contents of the tube, and then continuously sampled for 5 minutes. The liquid residence time was 40 seconds, and within the reaction tube, gas and liquid phases alternated in the direction of transfer. The unreacted chlorine, calculated from the effective chlorine concentration in the sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared downstream of the reaction tube for chlorine leakage prevention, was equivalent to 0.2% of the total chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 6.7% by mass, pH 13.8, liquid temperature 30°C) was obtained. The chlorine yield was over 99%, and storage stability was good.

[0048] <Example 5> This example shows an experimental case where the reaction tube in Example 4 was not modified. A straight tubular reaction tube, identical to that used in Comparative Example 1, was installed horizontally. A tetramethylammonium hydroxide solution (concentration 25.0% by mass, pH 14.4, liquid temperature 6°C) was supplied from one end of the reaction tube at a rate of 75 ml / min, and chlorine at a rate of 75.9 mmol / min. The reaction solution obtained from the outlet end of the reaction tube was discarded for 1 minute from the start of operation to allow for tube replacement, and then continuously sampled for 5 minutes. The liquid residence time was 40 seconds, and within the reaction tube, gas and liquid phases alternated in the direction of transfer. The unreacted chlorine, calculated from the effective chlorine concentration in a sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared downstream of the reaction tube for chlorine leakage prevention, amounted to 13% of the total supplied chlorine. As a result, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 6.0% by mass, pH 14.0, liquid temperature 27°C) was obtained. The chlorine yield was over 99%, and the storage stability was moderately good.

[0049] <Example 6> A spiral reaction tube was formed by rotating a PTFE (fluoropolymer) reaction tube (11 mm inner diameter, 10 m length) 20 times around a 150 mm diameter axis, with the horizontal axis as the axis of rotation. This reaction tube was placed horizontally in a container filled with cold water to perform the cooling operation. Subsequently, tetramethylammonium hydroxide solution (concentration 25% by mass, pH 14.4, liquid temperature 5°C) was supplied at 50 ml / min and chlorine at 68.3 mmol / min from the inlet side of the reaction tube. The reaction solution obtained from the outlet side of the reaction tube was discarded for 20 minutes from the start of operation to replace the contents of the tube, and then continuously sampled for 5 minutes. The liquid residence time was 19 minutes, and gas and liquid phases alternated within the reaction tube in the direction of transfer. The amount of unreacted chlorine, calculated from the effective chlorine concentration in the sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared downstream of the reaction tube for chlorine leakage prevention, was equivalent to less than 10 ppm of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 8.8% by mass, pH 12.0, liquid temperature 15°C) was obtained. The chlorine yield was over 99%, and the storage stability was good.

[0050] <Example 7> A spiral reaction tube, identical to that used in Example 6, was installed horizontally. Tetramethylammonium hydroxide solution (concentration 10.0% by mass, pH 14.0, liquid temperature 15°C) was supplied at 2.5 L / min and chlorine at 1.12 mol / min from the inlet side of the reaction tube, and the reaction solution obtained from the outlet side of the reaction tube was continuously sampled from the start of chlorine supply. The liquid residence time was 20 seconds, and as shown in Figure 2, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 3.1% by mass, pH 13.3, liquid temperature 25°C) was stably obtained from 1 minute after the start of chlorine supply. In the reaction tube, gas and liquid phases alternated in the direction of transfer. The unreacted chlorine, calculated from the effective chlorine concentration in the sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared in the downstream process of the reaction tube to prevent chlorine leakage, was equivalent to less than 100 ppm by mass of the total amount of chlorine supplied. The chlorine yield was over 99%, and storage stability was good.

[0051] <Example 8> A spiral reaction tube was formed by rotating a PTFE (fluoropolymer) reaction tube (11 mm inner diameter, 3 m length) six times around a 150 mm diameter axis, with the horizontal axis as the axis of rotation. A tetramethylammonium hydroxide solution (concentration 5.0% by mass, pH 13.7, liquid temperature 12°C) and chlorine were supplied at a rate of 110 ml / min and 24.3 mmol / min from the inlet side of the reaction tube, which was positioned horizontally. The reaction solution obtained from the outlet side of the reaction tube was continuously sampled from the start of chlorine supply. The liquid residence time was 2 minutes, and as shown in Figure 2, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 1.5% by mass, pH 13.0, liquid temperature 17°C) was stably obtained from 3 minutes after the start of chlorine supply. Inside the reaction tube, gas and liquid phases alternated in the direction of transfer. The waste liquid generated during the substitution operation until the reaction stabilized was 0.2 L, and the amount of unreacted chlorine was equivalent to less than 100 ppm by mass of the total amount of chlorine supplied.

[0052] <Comparative Example 2> A 150 mm diameter cylindrical reaction tube (made of PTFE) was used, and 1700 mL of tetramethylammonium hydroxide solution (5.0% by mass, pH 13.7, liquid temperature 12°C) was charged. A tetramethylammonium hydroxide solution of the same composition was supplied to the reactor at a rate of 110 mL / min, along with chlorine gas at a rate of 24.3 mmol / min. The resulting tetramethylammonium hypochlorite solution was removed from a liquid outlet located 100 mm above the bottom of the reactor. The liquid residence time was 16 minutes. As shown in Figure 2, a quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 1.5% by mass, pH 13.0, liquid temperature 17°C) was stably obtained 60 minutes after the start of chlorine supply. Inside the reaction tube, the gas phase and liquid phase were separated into upper and lower layers and did not alternate in the direction of transfer. 6.7 L of waste liquid was generated during the displacement operation until the reaction stabilized, and the unreacted chlorine amounted to 2% of the total chlorine supplied.

[0053] <Example 9> A spiral reaction tube, identical to that used in Example 8, was installed horizontally, and tetramethylammonium hydroxide solution (concentration 8.5% by mass, pH 14.0, liquid temperature 10°C) was supplied from the inlet side of the reaction tube at a rate of 1000 ml / min, along with chlorine at a rate of 436 mmol / min. Inside the reaction tube, gas and liquid phases alternated in the direction of transfer. The quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 3.0% by mass, pH 13.0, liquid temperature 20°C) obtained from the outlet side of the reaction tube had a production rate of 62 L / H per hour.

[0054] <Comparative Example 3> A quaternary tetramethylammonium hypochlorite solution (effective chlorine concentration 3.0% by mass, pH 13.0, liquid temperature 5°C) was obtained using the production method described in Example 3 of the prior art (International Publication No. 2019 / 225541). The reaction time using this method was 180 minutes, and the yield per hour was 0.34 L / H. [Table 1] *The "liquid-gas ratio" in the table is the ratio of the volume flow rate of halogen (chlorine gas) to the volume flow rate of organic alkaline solution (tetramethylammonium hydroxide solution). [Explanation of symbols]

[0055] 1 reaction tube 2. Quaternary alkylammonium hydroxide solution supply piping 3. Chlorine gas supply piping 4. Nitrogen gas supply piping 5. Piping valves 6. Piping valves 7. Piping valves 8. Reaction solution extraction piping 9. Reaction solution temperature measuring device 10. Reaction tube temperature control jacket 11. Reaction solution pH measuring device 12 Reaction solution storage tank 13. Caustic soda abatement equipment 14 Exhaust gas piping 15 Exhaust gas piping 16. Gas phase section 17 Liquid phase

Claims

1. A method for producing hypochlorous acid, comprising the steps of continuously supplying an organic alkaline solution and chlorine gas from one end of a reaction tube to the other, repeatedly alternating between a liquid phase and a gas phase within the transfer passage of the reaction tube, and mixing the organic alkaline solution and chlorine gas in the liquid phase and / or gas phase, wherein the pH of the reaction solution of the organic alkaline solution and chlorine gas supplied into the reaction tube is 10.5 to 13.8 at 25°C.

2. The method for producing hypochlorous acid according to claim 1, wherein the ratio of the volume flow rate of chlorine gas to the volume flow rate of the organic alkaline solution supplied to the reaction tube is 1 to 50.

3. The method for producing hypochlorous acid according to claim 1 or 2, wherein the reaction tube extends axially while rotating around an axis in the direction from one end to the other.

4. The method for producing hypochlorous acid according to claim 1 or 2, wherein the reaction tube is arranged to extend substantially horizontally.

5. The method for producing hypochlorous acid according to claim 1 or 2, wherein the reaction tube is a reaction tube formed in a spiral shape with the axis extending from one end to the other as the helical axis.

6. The method for producing hypochlorous acid according to claim 1 or 2, wherein the reaction tube is a reaction tube containing fluororesin.

7. The method for producing hypochlorous acid according to claim 1 or 2, wherein the average inner diameter of the reaction tube is 5 mm or more.

8. A hypochlorous acid production apparatus comprising a reaction tube that extends axially while rotating around an axis that extends from one end to the other, the reaction tube being positioned so that the axis extends substantially horizontally, an organic alkaline solution and chlorine gas being continuously supplied from one end to the other, alternating between a liquid phase and a gas phase within the transfer passage of the reaction tube, and a gas-liquid mixture of the organic alkaline solution and chlorine gas being performed in the liquid phase and / or gas phase. A hypochlorous acid production apparatus wherein the pH of the reaction solution of an organic alkaline solution and chlorine gas supplied into the reaction tube is 10.5 to 13.8 at 25°C.

9. The hypochlorous acid production apparatus according to claim 8, further comprising means for supplying an organic alkaline solution and chlorine gas to the reaction tube in a ratio such that the ratio of the volume flow rate of chlorine gas to the volume flow rate of the organic alkaline solution is 1 to 50.

10. The apparatus for producing hypochlorous acid according to claim 8 or 9, wherein the reaction tube is a spirally formed reaction tube, and the spiral axis of the reaction tube is arranged to extend substantially horizontally.

11. The apparatus for producing hypochlorous acid according to claim 8 or 9, wherein the reaction tube is a reaction tube containing fluororesin.

12. The hypochlorous acid production apparatus according to claim 8 or 9, wherein the average inner diameter of the reaction tube is 5 mm or more.

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