Method and device for producing halogen oxyacid

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

Method for producing halogen oxyacid and production apparatus thereof

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

[0002] Various methods have been attempted to achieve the desired treatment by mixing a gas that is soluble in the target liquid. For example, a method is known in which a gas is absorbed while circulating the liquid in a tank to obtain a liquid of a predetermined concentration (Patent Document 1). To achieve this more efficiently, a tubular device is also known, without using a tank. Examples include the production of ozonated water by injecting ozone into flowing water (Patent Document 2), and the neutralization treatment of alkaline wastewater by injecting carbon dioxide gas into the water (Patent Document 3).

[0003] JP 2005-21798 A JP 2010-221180 A JP 53-118278 A

[0004] While the above-mentioned gas dissolution methods are not problematic when used within the range of gas amounts that allow complete dissolution in the liquid, each method has drawbacks when used to dissolve large amounts of gas into a liquid. Specifically, when using a gas with low solubility in the target liquid, undissolved gas leaks out of the system, resulting in the waste of more gas than necessary. If environmentally hazardous gases such as ozone or halogens leak out of the system, leakage control measures must be implemented to render them harmless. For example, increasing the solubility of the gas in the liquid can be achieved by increasing the time and frequency of contact between the gas and the liquid. However, this requires increasing the volume of the equipment or installing a line mixer for mixing during the process. Both of these methods require large equipment and complex structures, which significantly impact costs and quality.

[0005] Therefore, the present invention focuses on the solubility of halogens in organic alkaline solutions, and has arrived at dissolving them by gas-liquid mixing in a pipe without using a line mixer. The present invention eliminates the need for a large-sized apparatus and a complex structure. Furthermore, the present invention provides an industrially superior method and apparatus for producing a halogen oxyacid solution that is efficient, high-quality, and produces little unreacted halogen.

[0006] As a result of extensive research to achieve the above object, the present inventors have found a method and an apparatus for industrially producing a halogen oxyacid more stably and efficiently, in which an organic alkali solution and a halogen are continuously supplied from one end of a reaction tube to the other, and a liquid phase and a gas phase are alternately and repeatedly present in a transfer passage of the reaction tube, thereby causing gas-liquid mixing of the organic alkali solution and the halogen in the liquid phase and / or the gas phase, and have completed the present invention.

[0007] That is, the present invention is configured as follows. Item 1. A method for producing a halogen oxyacid, comprising the steps of continuously supplying an organic alkali solution and a halogen from one end to the other end of a reaction tube, alternately and repeatedly presenting a liquid phase and a gas phase in a transfer passage of the reaction tube, and performing gas-liquid mixing of the organic alkali solution and the halogen in the liquid phase and / or the gas phase. Item 2. The method for producing a halogen oxyacid according to Item 1, wherein a ratio of a volumetric flow rate of the halogen to a volumetric flow rate of the organic alkali solution supplied to the reaction tube is 1 to 50. Item 3. The method for producing a halogen oxyacid according to Item 1 or 2, wherein the reaction tube is extended in an axial direction while rotating around an axis extending from one end to the other end. Item 4. The method for producing a halogen oxyacid according to any one of Items 1 to 3, wherein the reaction tube is disposed so as to extend in a substantially horizontal direction. Item 5. The method for producing a halogen oxyacid according to any one of Items 1 to 4, wherein the reaction tube is formed in a spiral shape with an axis extending from one end to the other end as an axis. Item 6. The method for producing a halogen oxyacid according to any one of Items 1 to 5, wherein the reaction tube comprises a fluororesin. Item 7. The method for producing a halogen oxyacid according to any one of Items 1 to 6, wherein the reaction tube has an average inner diameter of 5 mm or more. Item 8. An apparatus for producing a halogen oxyacid, comprising: a reaction tube extending in an axial direction while rotating around an axis extending from one end to the other end, the reaction tube being arranged so that the axis extends substantially horizontally, an organic alkali solution and a halogen are continuously supplied from one end to the other end, a liquid phase and a gas phase are alternately present in a transfer passage of the reaction tube, and the organic alkali solution and the halogen are mixed in a gas-liquid state in the liquid phase and / or the gas phase. Item 9. The apparatus for producing a halogen oxyacid according to Item 8, further comprising means for supplying the organic alkali solution and the halogen to the reaction tube at a ratio of a volumetric flow rate of the halogen to a volumetric flow rate of the organic alkali solution of 1 to 50. Item 10. The apparatus for producing a halogen oxyacid according to Item 8 or 9, wherein the reaction tube is a reaction tube formed in a spiral shape and is disposed so that a spiral axis of the reaction tube extends in a substantially horizontal direction. Item 11. The apparatus for producing a halogen oxyacid according to any one of Items 8 to 10, wherein the reaction tube is a reaction tube containing a fluororesin.Item 12. The apparatus for producing a halogen oxyacid according to any one of Items 8 to 11, wherein the reaction tube has an average inner diameter of 5 mm or more. Item 13. The apparatus for producing a halogen oxyacid according to any one of Items 8 to 12, wherein the reaction tube is configured so that the organic alkaline solution has a residence time of 5 seconds to 30 minutes.

[0008] An organic alkaline solution and a halogen are continuously supplied to one end of the reaction tube, and a reaction liquid containing the halogen oxygen acid produced is continuously withdrawn from the other end of the reaction tube. Frequent gas-liquid mixing occurs in the reaction tube mixture, maintaining constant component concentrations and pH of the organic alkaline solution (raw material) and the halogen oxygen acid produced in a steady state. This suppresses side reactions and other problems, resulting in a reaction liquid with good storage stability. Furthermore, the reduction in unreacted halogen reduces waste of raw materials. This also shortens the time from the start of the reaction to obtaining a reaction liquid with a stable composition, thereby reducing the amount of waste liquid generated and enabling efficient and stable production of the halogen oxygen acid. Furthermore, the continuous supply of raw materials and continuous withdrawal of the reaction product enable industrial mass production.

[0009] 1 is a schematic diagram showing one aspect of a production apparatus according to an embodiment of the present invention; 2 is a diagram showing the relationship between operation time and effective chlorine concentration when using a production method according to an embodiment of the present invention and a comparative example; 3 is a schematic diagram showing the state of a gas phase and a liquid phase in a reaction tube, where (a) shows a state in which a liquid phase and a gas phase alternate in the reaction tube, and (b) shows a state in which a liquid phase and a gas phase do not alternate in the reaction tube.

[0010] <Method for Producing Halogen Oxygen Acid> (Reaction Type, Reaction Tube) Next, one of the features of this embodiment is that an organic alkaline solution and a halogen are continuously supplied, and a reaction solution containing the generated halogen oxyacid is continuously withdrawn. Preferably, the reaction solution containing the halogen oxyacid is continuously withdrawn in an amount corresponding to the amounts of the organic alkaline solution and halogen continuously supplied. "A corresponding amount" means an amount that is the same as or proportional to the total amount of the organic alkaline solution and halogen supplied (total amount of organic alkaline solution and halogen > amount withdrawn: both by volume). The same applies to the production apparatus described below.

[0011] In the present invention, it is preferable to maintain constant the amounts of the organic alkaline solution and the halogen oxyacid produced, which are components in the reaction tube at a steady state, and the pH of the reaction solution removed from the reaction tube, and it is a preferred embodiment to precisely adjust the supply amounts. In conventional semi-batch reaction systems, the process involves adding halogen to an organic alkaline solution charged in a reactor, so the pH of the reaction solution tends to be high at the beginning of the reaction, and decomposition of the halogen oxyacid is likely to occur at high pH. Furthermore, in the halogen oxyacid produced in a high pH range, decomposition products are generated by the decomposition of the halogen oxyacid, posing a storage stability issue. On the other hand, if the organic alkaline solution and halogen are continuously supplied and the reaction solution is continuously removed, the reaction solution in the reaction tube reaches a steady state after a certain period of time, maintaining a constant pH, and therefore decomposition of the halogen oxyacid after the stable state is achieved is suppressed.

[0012] According to the production method of the present invention, it is possible to prevent the pH of the reaction solution from remaining high for a long time. The pH in the present invention is a value at 25°C unless otherwise specified. By continuously supplying an organic alkaline solution and a halogen and continuously withdrawing the reaction solution containing the generated halogen oxyacid, the residence time of the high pH, ​​which causes the greatest side reaction in this reaction, can be reduced. When chlorine gas or chlorine is used as an example of the halogen, a high chlorine yield can be maintained as a result. The chlorine yield here can be calculated from the ratio (%) of the number of moles of hypochlorite ions generated to the number of moles of chlorine molecules supplied to the organic alkaline solution. When all of the chlorine added to the organic alkaline solution reacts (no decomposition occurs), the chlorine yield is 100%. When hypochlorite ions decompose during the reaction, the chlorine yield decreases. In the present invention, the reaction tube refers to a device in which a chemical reaction takes place during the production of a chemical substance. It is preferable that the organic alkaline solution and halogen are continuously supplied to the reaction tube at a constant rate. Supplying at a constant rate means that the supply rate is constant. Furthermore, continuous removal of the reaction solution does not have to start simultaneously with the start of the production method according to an embodiment of the present invention, and may be started after the pH of the reaction solution removed from the reaction tube has become constant.

[0013] In addition, it is a preferred embodiment to make the pH of the components and reaction solution in the reaction tube uniform. The pH of the reaction solution of the organic alkaline solution and halogen supplied to the reaction tube is preferably 10.5 to 14.5. It is more preferable that the pH of the reaction solution of the organic alkaline solution and halogen is 10.5 to 13.8. It is even more preferable that the pH of the reaction solution of the organic alkaline solution and halogen is 12.0 to 13.8. It is also preferable that the pH of the reaction solution withdrawn from the reaction tube is 12.0 to 13.8.

[0014] To mix the organic alkaline solution and halogen in the reaction tube, it is preferable to alternately separate liquid and gas phases in the transfer passageway in the direction of transfer. This allows for uniform mixing of the liquids without the need for a line mixer installed in the tube. Line mixers (agitators) are typically used to achieve uniform mixing of the fluids passing through the tube. Line mixers typically include those that mix the fluids by driving impellers installed in the tube's internal space, or in-line mixers (static mixers) that mix the fluids by passing them through elements fixed in the tube's internal space. While these line mixers are used for efficient fluid mixing, in applications requiring high-purity liquids that are unsuitable for contamination by particles, metal components, etc., such as semiconductor chemicals, installation of a line mixer within the tube can be difficult because contamination from liquid contact points significantly affects quality. Without a line mixer, the gas-liquid mixing ability in a reaction tube is reduced, resulting in non-uniform reaction liquid concentrations and short-path gas phases within the tube, making this a disadvantageous industrial production method.

[0015] When liquid and gas phases do not alternate in the transfer path of the reaction tube, the number and frequency of gas-liquid contacts decreases, resulting in a poor gas-liquid mixing state within the tube. In this case, an additional process to improve the gas-liquid mixing state is required to stabilize the liquid composition. If a line mixer is not installed in the tube, the length of the reaction tube must be extended. Lengthening the reaction tube not only increases equipment costs but also increases the amount of waste liquid generated during the replacement of the reaction tube, resulting in cost disadvantages in terms of both equipment and raw materials. The alternating liquid and gas phases in the transfer path of the reaction tube, as in the present invention, subdivides the number and frequency of gas-liquid contacts within the reaction tube, creating a condition similar to a pseudo-plug flow within the reaction tube, enabling the continuous production of a reaction solution with a uniform concentration. This allows the organic alkali solution and halogen to be uniformly mixed within the reaction tube, eliminating the need for a line mixer. Due to these effects, the present invention is also characterized by the fact that a liquid with a stable composition can be continuously obtained by replacing the reaction solution in the reaction tube only once. In other words, the volume required to replace the state inside the tube from the organic alkaline solution before the reaction to the liquid after the reaction is determined by the length from the inlet to the outlet of the reaction tube. This allows the operation of replacing the inside of the tube with the reaction liquid to be optimized, and the amount of waste liquid that is unnecessary from the start of the reaction until the liquid composition stabilizes can be minimized, which is industrially advantageous.

[0016] The simplest method for alternately arranging liquid and gas phases within the reaction tube is to set the diameter of the supply pipes supplying the gas and liquid phases to be equal to or smaller than the diameter of the reaction tube. This allows alternately creating gas and liquid phases with 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 volumetric flow rate per hour of the gas phase supplied to the reaction tube divided by the volumetric flow rate per hour of the liquid phase supplied to the reaction tube) is 1 or greater, the halogen present in the gas phase does not dissolve sufficiently in the liquid phase, and is discharged as undissolved halogen from the outlet side of the reaction tube. One possible solution is to extend the time until the halogen dissolves by extending the length of the reaction tube. However, a more convenient method for promoting the dissolution of the halogen in the reaction tube is to extend the reaction tube while rotating the reaction tube in the axial direction. That is, a preferred configuration is to extend the reaction tube in the axial direction while rotating the reaction tube around the axis extending from one end to the other end of the reaction tube. 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 stretching axis may be inclined in some way, and among the inclined axial directions, it is more preferable to stretch the reaction tube in a substantially horizontal direction.

[0017] The diameter of the rotation required for swirling in the axial direction can be determined depending on the length of the reaction tube and the strength of the material used, and can be, for example, 30 mm or more and 3,000 mm or less, preferably 60 mm or more and 600 mm or less. By forming a swirling motion of the reaction tube at least once, the effect of improving the gas-liquid mixing efficiency can be obtained. In the reaction tube, the gas phase basically rises due to buoyancy generated according to the volume of the gas, and the liquid phase descends due to gravity. However, by swirling the reaction tube, the gas phase always comes into contact with the liquid phase accumulated in the lower vertical position at least once. Therefore, the higher the number of revolutions of the reaction tube, the more advantageous it is for gas-liquid mixing and the more effective it is for preventing short-passing of the gas phase. The gas phase may not be present in the lower vertical position of the reaction tube. Furthermore, the lengths of the gas phase and the liquid phase present in the reaction tube in the transport direction may be uneven. Although there is no upper limit to the number of revolutions of the rotating reaction tube, it is preferably formed by 2 or more revolutions, more preferably 5 or more revolutions, and even more preferably 10 or more revolutions. On the other hand, the upper limit of the number of revolutions is usually 50 or less. Furthermore, 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. Regarding the appearance of the apparatus satisfying these apparatus configurations, it is most preferable that the reaction tube is formed in a spiral shape along the axial direction, but the shape of the reaction tube is not limited thereto. It is also preferable that the reaction tube is alternately bent along the axial direction or processed into a wavy line shape along the axial direction. The inner diameter and length of the reaction tube affect the volume of the reaction solution and are therefore important factors for industrial mass production of the reaction solution. The industrial mass production referred to here means efficient and continuous production of the target reaction solution while reducing the amount of waste liquid generated, and the production amount per hour is preferably at least equal to the volume of liquid occupying the tube, more preferably at least 5 times, and even more preferably at least 100 times.

[0018] In addition to the organic alkaline solution and halogen continuously supplied to the reaction tube, an inert gas may be supplied to the reaction tube. Supplying an inert gas not only creates an alternating liquid phase and a gas phase within the reaction tube, but also prevents backflow of the liquid and gas phases within the system. The inert gas refers to a stable gas unrelated to the reaction, such as air, nitrogen, argon, or helium. Air is preferred from an economical standpoint. However, because carbon dioxide contained in air can dissolve in the reaction solution, causing a decrease in pH, or react to produce impurities, the use of a highly purified inert gas is more preferred, and nitrogen is particularly preferred from an economical standpoint. The volume within the reaction tube can be varied depending on the supply rate of the organic alkaline solution used. If the liquid residence time is defined as the volume within the reaction tube divided by the volume of the organic alkaline solution per hour supplied to the reaction tube, a volume of the reaction tube that allows the liquid residence time of the organic alkaline solution in the reaction tube to be preferably 5 seconds to 30 minutes is a preferred embodiment, and more preferably 10 seconds to 5 minutes. In the present invention, a liquid with a stable composition can be continuously obtained by simply replacing the reaction liquid once in the reaction tube. This means that the time required to obtain a stable liquid composition is directly related to the liquid residence time. If the mixing state in the tube is insufficient at the start of the reaction, a time at least three times longer than the liquid residence time is required to obtain a liquid with a stable composition. Furthermore, the supply rate of the halogen, expressed as a ratio of the volumetric flow rate of the halogen to the volumetric flow rate of the organic alkaline solution supplied to the reaction tube, is preferably 1 to 50, more preferably 10 to 30. Within this range, even if the shape of the reaction tube is not the above-described one in which the tube is extended while rotating around the axial direction of the reaction tube, it can contribute to realizing an embodiment in which a gas phase and a liquid phase alternate in the transport direction within the reaction tube. Note that the volumetric flow rate of the halogen supplied to the reaction tube is calculated based on a pressure of 0°C and 1 atm when the halogen is a gas. The halogen supplied to the reaction tube dissolves in the organic alkaline solution within the tube, thereby degassing the dissolved gas in the solution. That is, the halogen generates heat of dissolution in the reaction tube, causing the temperature of the solution to rise, and the dissolved gas that can no longer be dissolved in the liquid moves out of the liquid, resulting in a degassing effect.As the liquid-gas ratio increases, the heat of dissolution increases in proportion to the amount of halogen supplied, making it easier to achieve the degassing effect. Dissolved gases include, but are not limited to, nitrogen, oxygen, and carbon dioxide. Cylindrical reaction tubes are also available, but this refers to a state in which 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 period of time, which is the effect of the present invention. In other words, the reaction tube must be provided with additional locations necessary for liquid flow, and liquid replacement within the reaction tube is difficult to progress, making it difficult to stabilize the liquid composition. Therefore, the liquid must be discarded until it stabilizes. The present invention, which achieves stability through a single liquid replacement, is economically advantageous because it reduces the amount of waste liquid generated.

[0019] (Organic Alkali Solution) The organic alkali solution supplied to the reaction tube may be either an aqueous solution in which an organic alkali is dissolved in water or a solution in which an organic alkali is dissolved in a non-aqueous solvent. The organic alkali solution can be obtained by dissolving an organic alkali in water or a non-aqueous solvent, or by diluting a commercially available organic alkali solution to the desired concentration. Among these water and non-aqueous solvents, water is preferred because it is easily available industrially and can produce a high-purity organic alkali solution. Examples of non-aqueous solvents include known organic solvents capable of dissolving organic alkalis. Specific examples include alcohols and glycols, with methanol and propylene glycol being particularly preferred. The concentration of the organic alkali solution is not particularly limited, but if the organic alkali concentration becomes high, a salt will precipitate and become a 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] The solvent used for the organic alkaline solution may be an aqueous solution containing only water, a non-aqueous solution obtained by mixing with an organic solvent, or a mixture of an aqueous solution and an organic solvent. The solvent may be appropriately selected depending on the application of the solution containing a halogen oxygen acid. For example, when the object to be cleaned is ruthenium, water alone is sufficient for cleaning, so an organic alkaline aqueous solution may be used. In this embodiment, the organic alkaline solution is preferably an onium hydroxide solution, and examples of the 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, an ammonium hydroxide solution, which contains a large number of relatively stable compounds, is more preferable. Furthermore, the above-mentioned onium hydroxide solution is preferably an aqueous onium hydroxide solution. Furthermore, the above-mentioned ammonium hydroxide solution is preferably a quaternary alkylammonium hydroxide solution.

[0021] The quaternary alkylammonium hydroxide solution is preferably a solution of a quaternary alkylammonium hydroxide in which the alkyl groups independently have 1 to 10 carbon atoms, and more preferably a solution of a quaternary alkylammonium hydroxide in which the alkyl groups independently have 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 alone or in combination of two or more. Furthermore, the four alkyl groups contained in the quaternary alkylammonium hydroxide may have the same or different carbon atoms. 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 the specific organic alkali used.

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

[0023] (Process for producing a reaction solution containing a halogen oxyacid by gas-liquid mixing of an organic alkaline solution and a halogen) In the process for producing a reaction solution containing a halogen oxyacid by gas-liquid mixing of an organic alkaline solution and a halogen and reacting them, the pH of the reaction solution containing the halogen oxyacid produced in the reaction tube tends to decrease. In this embodiment, the lower limit of the pH of the organic alkaline solution used as the raw material is 10.5 or more, preferably 11.0 or more, more preferably 11.5 or more, and particularly preferably greater than 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 less. Furthermore, the organic alkaline solution used in this embodiment preferably has a metal content, specifically, sodium, potassium, aluminum, magnesium, iron, nickel, copper, silver, cadmium, and lead, of 0.01 ppb or more and 20 ppb or less. Of course, the metal content of the organic alkaline solution used may be less than 0.01 ppb, but obtaining such an organic alkaline solution is difficult. Therefore, by using an organic alkaline solution whose content of the above metals satisfies the above range, the organic alkaline solution itself becomes easy to obtain, and the metal impurities can be easily removed and reduced during and after the production of the reaction solution containing the halogen oxyacid. Furthermore, since the above metals are eluted from the area in the reaction tube that comes into contact with the organic alkaline solution, it is preferable to provide a reaction tube with a small liquid contact area. That is, a reaction tube with a small volume is an important factor for reducing impurities and is also very effective in terms of quality control. Although there is no upper limit to the range of the liquid contact area of ​​the reaction tube, a suitable liquid contact area is 0.01 m. 2 More than 10m 2 More preferably, it is 0.1 m or less. 2 More than 1.0m 2 The following is the result.

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

[0025] (Reactions Occurring by Contacting an Organic Alkaline Solution with a Halogen) For example, when a quaternary alkylammonium hydroxide is used as the organic alkali, contacting and reacting the solution with a halogen replaces the hydroxide ions of the quaternary alkylammonium hydroxide with hypochlorite ions generated by the halogen, 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, hypoiodous acid, chlorous acid, bromous acid, iodous acid, chloric acid, bromic acid, and iodic acid. When chlorine or bromine is used, these gases can be used. Among these, chlorine gas is preferably used. 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 alkyl ammonium hydroxide solution is used as the organic alkaline solution and chlorine gas is used as the halogen, but this is merely an example.

[0026] (pH of the liquid phase during 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 liquid produced by mixing the quaternary alkylammonium hydroxide solution and chlorine gas during the reaction. The upper limit of the pH of the liquid phase is not particularly limited, but if the pH during the reaction is excessively high, hypochlorite ions may be decomposed and the effective chlorine concentration may decrease if the solution is stored for a long period of time at the same pH after the reaction is completed. Therefore, the pH of the liquid phase during the reaction is preferably 10.5 or higher and 14.5 or lower, more preferably 10.5 or higher and 13.8 or lower, and even more preferably 12 or higher and 13.8 or lower. If the pH is within the above range, the decomposition of hypochlorite ions is suppressed during storage of the resulting quaternary alkylammonium hypochlorite solution, improving storage stability.

[0027] (Reaction Temperature) The reaction temperature range in the production method of this embodiment is preferably −35°C or higher and 45°C or lower, more preferably −15°C or higher and 40°C or lower, and even more preferably −5°C or higher and 35°C or lower. When the reaction temperature is within the above range, the organic alkali hydroxide solution reacts sufficiently with the halogen, resulting in a high yield of halogen oxyacid. If the reaction temperature is lower than −35°C, the organic alkali begins to solidify, preventing sufficient reaction with the halogen. On the other hand, if the reaction temperature exceeds 45°C, the halogen oxyacid ions generated in the halogen oxyacid solution decompose due to heat. Particularly when the pH during the reaction is 13.8 or higher, the decomposition of the halogen oxyacid becomes significant as the reaction temperature increases. The yield of the halogen oxyacid can be evaluated by the chlorine yield. As described above, the production method of this embodiment can produce a halogen oxyacid with excellent storage stability, for example, one that can maintain sufficient cleaning and removing power even 10 days after production. As is clear from this, the halogen oxyacid obtained by the production method of this embodiment has excellent storage stability and can be suitably used in the production process of semiconductor devices.

[0028] (Material for the Inner Surface of the Reaction Tube) In this embodiment, the organic alkaline solution is contacted with the chlorine gas in the reaction tube to produce a halogen oxyacid. First, a predetermined amount of the organic alkaline solution is introduced into the reaction tube, and then chlorine gas is introduced so as to contact 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' investigations, when a general-purpose borosilicate glass (hereinafter, "glass") reaction tube is used as the reaction tube, metal components contained in the glass, such as sodium, potassium, and aluminum, dissolve to a certain extent in the organic alkaline solution. This is thought to be due to the alkalinity of the organic alkaline solution used as a raw material. Therefore, it is more preferable to form the inner surface of the reaction tube from an organic polymer material, which can further reduce the inclusion of impurities containing the above metals (metal impurities).

[0029] In addition, it is preferable that the reaction be carried out in a light-shielded environment, and specifically, it is preferable that the reaction tube be one in which the inside of the reaction tube is light-shielded. 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 present in the reaction tube and the halogen oxyacid generated by the reaction, causing decomposition. Furthermore, the halogen oxyacid itself may be decomposed by light, so it is preferable that the reaction tube, associated piping, etc. be light-shielded.

[0030] In this embodiment, when an organic solvent is used as the solvent, it is preferable that the reaction apparatus has an explosion-proof structure. Therefore, in order to simplify the apparatus configuration, it is preferable that water be used as the solvent for the organic alkaline solution. In this embodiment, examples of organic polymer materials that can be used for the inner surface of the reaction tube include vinyl chloride resins (soft and hard vinyl chloride resins), nylon resins, silicone resins, polyolefin resins (polyethylene, polypropylene), and fluororesins. Among these, fluororesins are preferred in terms of ease of moldability, solvent resistance, and low impurity elution. 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 polymer of perfluoro(butenyl vinyl ether). Among these, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is preferred in terms of ease of availability of the reaction tube itself, productivity, and the like.

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

[0032] In this embodiment, as long as 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 made of glass, stainless steel, or passivated stainless steel. In this embodiment, the organic alkaline solution and chlorine gas are brought into contact with each other in the reaction tube. The reaction temperature range is not particularly limited, but is preferably the same as the reaction temperature described above. Furthermore, the presence of carbon dioxide in the reaction system tends to decrease the pH of the resulting halogen oxyacid solution. Therefore, considering stable production, it is preferable to prevent carbon dioxide from being present in the reaction system. Specifically, it is preferable to use an organic alkaline solution, chlorine gas, or the like, with a reduced amount of carbon dioxide. Furthermore, it is preferable to carry out the reaction in the presence of an inert gas (e.g., nitrogen gas) with a reduced amount of carbon dioxide. By carrying out the reaction under these conditions, a decrease in the pH of the resulting halogen oxyacid solution can be suppressed, thereby improving storage stability.

[0033] <Halogen Oxygen Acid Production Apparatus> Next, an embodiment of the halogen oxyacid production apparatus will be described. The above production method can be carried out using the production apparatus of this embodiment. An example of the production apparatus according to this embodiment will be described, in which a quaternary alkylammonium hydroxide solution is used as the organic alkali and chlorine gas is used as the halogen. 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 for the halogen oxyacid production method. The production apparatus of this embodiment includes a reaction tube extending axially while rotating around its axis, with the axis extending from one end to the other. The reaction tube is arranged so that the axis extends substantially horizontally. An organic alkali solution and halogen are continuously supplied from one end to the other end, and a liquid phase and a gas phase are alternately present in the transfer passage of the reaction tube. The organic alkali solution and halogen are mixed in the liquid and / or gas phases. FIG. 1 shows a schematic diagram of the production apparatus according to this embodiment. The production apparatus shown in FIG. 1 comprises a reaction tube 1, a quaternary alkylammonium hydroxide solution supply pipe 2 as an organic alkali supply means to the reaction tube, a piping valve 5 for operating and stopping the liquid supply, a chlorine gas supply pipe 3 as a halogen supply means, and a piping valve 6 for operating and stopping the chlorine gas supply, and a reaction solution withdrawal pipe 8 as a reaction solution withdrawal means for withdrawing the reaction solution from the reaction tube. In the reaction tube 1, the quaternary alkylammonium hydroxide solution is supplied from the quaternary alkylammonium hydroxide solution supply pipe 2, and the chlorine gas is supplied from the chlorine gas supply pipe 3, both of which are continuously supplied. The chlorine gas supply operation and stopping operation are performed by the piping valve 6. The reaction solution produced is continuously withdrawn from the reaction solution withdrawal pipe 8. The conditions described in the above production method can be used for the parts where the quaternary alkylammonium hydroxide solution flows and comes into contact with the liquid. The inner surface of the reaction tube 1 is preferably formed of an organic polymer material. Specifically, the reaction tube is preferably a reaction tube containing a fluororesin, and it is preferable that the entire reaction tube 1 or at least its inner surface is made of a fluororesin.The fluororesin may be any of those exemplified above in the "material for the inner surface of the reaction tube."

[0034] As a chlorine gas supply means, it is preferable that the pipe diameters of the chlorine supply pipe 3 and the reaction tube 1 are the same. In order to facilitate dispersion of chlorine gas in the liquid phase, the pipe diameter of the chlorine gas supply pipe 3 may be smaller than that of the reaction tube 1. The blow-out speed of chlorine gas is preferably 0.1 m / sec or more and 10 m / sec or less, calculated at 0°C and 1 atm. The volume inside the reaction tube can be changed depending on the supply rate of the quaternary alkylammonium hydroxide solution used. When the liquid residence time is defined as the value obtained by dividing the volume of the reaction tube by the volume of the quaternary alkylammonium hydroxide solution per hour supplied to the reaction tube, a suitable embodiment is a reaction tube volume that results in a liquid residence time of the quaternary alkylammonium hydroxide solution of preferably 5 seconds to 30 minutes, more preferably 10 seconds to 5 minutes. Furthermore, the supply rate of the halogen to be supplied is preferably 1 to 50, more preferably 10 to 30, in terms of the ratio of the volumetric flow rate of the halogen to the volumetric flow rate of the organic alkaline solution supplied to the reaction tube.

[0035] The reaction tube is preferably extended in the axial direction while rotating around the axis extending from one end to the other. It is also preferable that the reaction tube is arranged so as to extend in a substantially horizontal direction. It is more preferable that the reaction tube is a spirally formed reaction tube and is arranged so that the spiral axis of the reaction tube extends in a substantially horizontal direction. The diameter of the rotation (inner diameter of the spiral circle) required for rotation can be determined depending on the length of the reaction tube and the strength of the material used, and can be, for example, 30 mm or more and 3000 mm or less, and preferably 60 mm or more and 600 mm or less. By rotating the reaction tube once or more, the effect of improving gas-liquid mixing can be obtained. Therefore, there is no upper limit to the rotation speed of the rotated reaction tube, but it is preferable to form an apparatus with at least two rotations, more preferably 5 rotations or more, and even more preferably 10 rotations or more. On the other hand, the upper limit of the rotation speed is usually 50 rotations or less. The higher the rotation speed of the reaction tube, the more advantageous it is for gas-liquid mixing. 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 or more and 500 mm or less, and even more preferably 10 mm or more and 100 mm or less.

[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 gas components supplied to the reaction tube 1. A piping valve 7 may also be provided for operating and stopping the nitrogen gas supply. The reaction between a quaternary alkylammonium hydroxide solution and chlorine is an exothermic reaction. In the production apparatus according to this embodiment, the temperature inside the reaction tube 1 can be measured, for example, using a reaction liquid temperature measuring device 9 as a temperature measuring device in the reaction tube 1. The production apparatus according to this embodiment may also 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 can be removed by the reaction tube temperature control jacket 10. The production apparatus according to this embodiment may also be equipped with a light-shielding means to perform the reaction under light-shielding conditions. The production apparatus according to this embodiment may also be equipped with a reaction liquid pH measuring device 11 disposed in the reaction liquid outlet pipe 8 as a means for measuring the pH of the reaction liquid. Because the measuring liquid used for pH measurement may cause contamination of the reaction liquid, it is more preferable to branch the line and allow it to flow. The pH of the reaction solution after the reaction can be measured by using the reaction solution pH measuring device 11. The production apparatus according to this embodiment preferably includes at least one of a reaction temperature measuring means, a reaction temperature control means, and a pH measuring means in the reactor described above, more preferably includes two of these, and even more preferably includes all of these.

[0037] A detoxification means may be provided downstream of the reaction liquid outlet pipe 8 to prevent unreacted chlorine and the like from being discharged outside the system, and specifically, a caustic soda detoxification device 13 may be installed. The caustic soda detoxification device 13 may be configured, for example, such that in a reaction liquid storage tank 12 that stores the reaction liquid delivered through the reaction liquid outlet pipe 8, gas contained in the reaction liquid generated in the gas phase of the storage tank is transferred to the caustic soda detoxification device 13 through an exhaust gas pipe 14 connected to the storage tank, and is submerged in a solution containing caustic soda. The gas phase of the caustic soda detoxification device 13 may also be provided with an exhaust gas pipe 15 for discharging the detoxified gas.

[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 30 mL of the quaternary alkylammonium hydroxide solution and the quaternary alkylammonium hypochlorite solution was measured using a benchtop pH meter (LAQUA F-73, manufactured by HORIBA, Ltd.) The pH measurement was performed after the solution had stabilized at 25°C.

[0040] <Method of calculating effective chlorine concentration and hypochlorite ion concentration> 0.5 mL of treatment solution (quaternary ammonium hypochlorite solution), 2 g of potassium iodide (Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent), 8 mL of 10% by weight acetic acid, and 10 mL of ultrapure water were added to a 100 mL Erlenmeyer flask and stirred until the solids dissolved to obtain a brown solution. The prepared brown solution was subjected to oxidation-reduction titration using 0.02 M sodium thiosulfate solution (Fujifilm Wako Pure Chemical Industries, Ltd., for volumetric analysis) until the color of the solution changed from brown to very light yellow, and then a starch solution was added to obtain a light purple solution. 0.02 M sodium thiosulfate solution was further added to this solution, and the effective chlorine concentration was calculated using the point where 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 weight, the hypochlorite ion concentration is 0.73% by weight.

[0041] <Chlorine yield> The chlorine yield was calculated from the ratio (%) of the number of moles of hypochlorite ions generated to the number of moles of chlorine molecules supplied to the organic alkaline solution. When all of the chlorine added to the organic alkaline solution reacts (no decomposition occurs), the chlorine yield is 100%. When hypochlorite ions decompose during the reaction, the chlorine yield decreases.

[0042] <Evaluation method for storage stability> The quaternary alkyl ammonium hypochlorite solution was transferred into a glove bag, and after the carbon dioxide concentration in the glove bag reached 1 ppm or less, it was transferred to a PFA (perfluoroalkoxy fluororesin: tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) container and sealed. Next, after storing in a light-shielded environment at 23°C for 10 days, the hypochlorite ion concentration of the quaternary alkyl ammonium hypochlorite solution in the PFA container was measured. A hypochlorite ion concentration ratio (concentration after 10 days / initial concentration) of 80% or more and 100% or less was rated as good, 60% or more and less than 80% as fair, and less than 60% as poor.

[0043] Example 1 A PFA (fluororesin) reaction tube (inner diameter 8 mm, length 1 m) was rotated six times around a horizontal axis with a diameter of 50 mm to form a spiral reaction tube, and the reaction tube was installed horizontally. Tetramethylammonium hydroxide solution (concentration 12.0% by mass, pH 14.1, liquid temperature 5°C) was supplied from the inlet side of the reaction tube at 370 ml / min and chlorine at 209.8 mmol / min. The reaction liquid obtained from the outlet side of the reaction tube was discarded for 1 minute from the start of operation for replacement inside the tube, and then continuously sampled for 5 minutes. The liquid residence time was 8 seconds, and gas and liquid phases alternated in the direction of transfer within the reaction tube. The unreacted chlorine calculated from the available chlorine concentration in a sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared downstream of the reaction tube to prevent chlorine leakage corresponded to less than 100 ppm by mass 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 99% or more and the storage stability was good. After the above sampling, continuous operation for 2 hours was carried out under the same conditions. The liquid composition of the sample obtained by sampling for 5 minutes 1 hour after the start of operation was 3.9% by mass and pH 13.4, and the liquid composition of the sample obtained by sampling for 5 minutes 2 hours after the start of operation was 3.9% by mass and pH 13.4. The production volume per hour was 23 L / H.

[0044] Comparative Example 1: As a comparative example, an experimental example in which the reaction tube in Example 1 was not modified is shown. A reaction tube (inner diameter 8 mm, length 1 m) made of PFA, a fluororesin, was stretched into a straight tube and installed horizontally. A tetramethylammonium hydroxide solution (concentration 12.0% by mass, pH 14.1, liquid temperature 5°C) was supplied from one end of the reaction tube at 370 ml / min and chlorine at 209.8 mmol / min. A short path of chlorine gas occurred within the reaction tube, causing the liquid supply to become unstable, and the liquid supply rate decreased to 140 ml / min. The liquid residence time was 22 seconds, and the gas and liquid phases within the reaction tube were separated into upper and lower two layers, and did not alternate in the direction of transport (see Figure 3(b)). The reaction liquid 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% by mass, 1000 ml) prepared in the subsequent step to prevent chlorine leakage was equivalent 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 the storage stability was poor.

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

[0046] Example 3 This is an experimental example in which the reaction tube in Example 2 was not modified. A reaction tube (inner diameter 8 mm, length 1 m) made of PFA, a fluororesin, was stretched into a straight tube and installed horizontally. Tetramethylammonium hydroxide solution (concentration 4.8% by mass, pH 13.7, liquid temperature 7°C) was supplied to one end of the reaction tube at 200 ml / min and chlorine at 12.5 mmol / min. The reaction liquid obtained from the outlet side of the reaction tube was discarded for 1 minute after the start of operation for replacement inside the tube, and then continuously sampled for 5 minutes. The liquid residence time was 15 seconds, and gas and liquid phases alternated in the direction of transfer within the reaction tube (see Figure 3(a)). Unreacted chlorine, calculated from the available chlorine concentration in a sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared downstream of the reaction tube to prevent chlorine leakage, corresponded to 5% of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (available chlorine concentration 0.4% by mass, pH 13.6, liquid temperature 8° C.) was obtained. The chlorine yield was 99% or more and the storage stability was good.

[0047] Example 4: The same spiral reaction tube as used in Example 1 was installed horizontally. Tetramethylammonium hydroxide solution (concentration 25.0% by mass, pH 14.4, liquid temperature 6°C) was supplied from the inlet side of the reaction tube at 75 ml / min and chlorine at 75.9 mmol / min. The reaction liquid obtained from the outlet side of the reaction tube was discarded for 1 minute from the start of operation for replacement inside the tube, and then continuously sampled for 5 minutes. The liquid residence time was 40 seconds, and gas phase and liquid phase portions alternated in the direction of transfer within the reaction tube. The unreacted chlorine calculated from the available chlorine concentration in a sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared downstream of the reaction tube to prevent chlorine leakage corresponded to 0.2% of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (available chlorine concentration 6.7% by mass, pH 13.8, liquid temperature 30°C) was obtained. The chlorine yield was 99% or more, and storage stability was good.

[0048] Example 5 This is an experimental example in which the reaction tube in Example 4 was not modified. A straight reaction tube identical to that used in Comparative Example 1 was installed horizontally. 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 75 ml / min and chlorine at 75.9 mmol / min. The reaction liquid obtained from the outlet side of the reaction tube was discarded for 1 minute from the start of operation for replacement inside the tube, and then continuously sampled for 5 minutes. The liquid residence time was 40 seconds, and within the reaction tube, gas phase and liquid phase portions alternated in the direction of transfer. The unreacted chlorine calculated from the available chlorine concentration in a sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared downstream of the reaction tube to prevent chlorine leakage corresponded to 13% of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (available 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 fairly good.

[0049] Example 6: A fluororesin PTFE reaction tube (inner diameter 11 mm, length 10 m) was rotated 20 times around a horizontal axis with a diameter of 150 mm to form a spiral reaction tube. The reaction tube was placed horizontally in a container filled with cold water to allow for cooling. Subsequently, a tetramethylammonium hydroxide solution (concentration 25% by mass, pH 14.4, liquid temperature 5°C) was supplied to the inlet side of the reaction tube at a rate of 50 ml / min and chlorine at a rate of 68.3 mmol / min. The reaction liquid obtained from the outlet side of the reaction tube was discarded for 20 minutes from the start of operation for replacement inside the tube, and then continuously sampled for 5 minutes. The liquid residence time was 19 minutes, and gas and liquid phases alternated in the reaction tube in the direction of transfer. The unreacted chlorine calculated from the available chlorine concentration in a sodium hydroxide solution (10% by mass, 1000 ml) prepared in the downstream process of the reaction tube to prevent chlorine leakage was equivalent to 10 ppm or less of the total amount of chlorine supplied. As a result, a quaternary tetramethylammonium hypochlorite solution (available chlorine concentration 8.8% by mass, pH 12.0, liquid temperature 15 ° C.) was obtained. The chlorine yield was 99% or more, and the storage stability was good.

[0050] Example 7 The same spiral reaction tube as used in Example 6 was installed horizontally. Tetramethylammonium hydroxide solution (concentration 10.0% by mass, pH 14.0, liquid temperature 15°C) was supplied from the inlet side of the reaction tube at 2.5 L / min and chlorine at 1.12 mol / min, and the reaction solution obtained from the outlet side of the reaction tube was continuously sampled after 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. Within the reaction tube, gas phase and liquid phase portions alternated in the transfer direction. The unreacted chlorine calculated from the effective chlorine concentration in a sodium hydroxide solution (concentration 10% by mass, 1000 ml) prepared in a downstream process to prevent chlorine leakage corresponded to less than 100 ppm by mass of the total amount of chlorine supplied. The chlorine yield was 99% or more and the storage stability was good.

[0051] Example 8 A spiral reaction tube (inner diameter 11 mm, length 3 m) made of PTFE, a fluororesin, was rotated six times with a diameter of 150 mm around a horizontal axis, forming a spiral reaction tube. Tetramethylammonium hydroxide solution (concentration 5.0% by mass, pH 13.7, liquid temperature 12 ° C.) was supplied at 110 ml / min and chlorine at 24.3 mmol / min from the inlet side of the reaction tube, which was placed horizontally. The reaction solution obtained from the outlet side of the reaction tube was continuously sampled after 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 after 3 minutes from the start of chlorine supply. In the reaction tube, gas phase and liquid phase were alternately present in the direction of transport. The amount of waste liquid generated during the replacement operation until the reaction stabilized was 0.2 L, and the amount of unreacted chlorine was equivalent to 100 ppm by mass or less of the total amount of chlorine supplied.

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

[0053] Example 9 The same spiral reaction tube as used in Example 8 was installed horizontally, and a 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 1000 ml / min, and chlorine was supplied at 436 mmol / min. In the reaction tube, gas phase and liquid phase were alternately present in the transfer direction. 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 by the production method of Example 3 in the prior art (WO 2019 / 225541). The reaction time by this production method was 180 minutes, and the production amount per hour was 0.34 L / H. *The "liquid-gas ratio" in the table is the ratio of the volumetric flow rate of the halogen (chlorine gas) to the volumetric flow rate of the organic alkaline solution (tetramethylammonium hydroxide solution).

[0055] REFERENCE SIGNS LIST 1 Reaction tube 2 Quaternary alkylammonium hydroxide solution supply pipe 3 Chlorine gas supply pipe 4 Nitrogen gas supply pipe 5 Pipe valve 6 Pipe valve 7 Pipe valve 8 Reaction liquid withdrawal pipe 9 Reaction liquid temperature measuring device 10 Reaction tube temperature control jacket 11 Reaction liquid pH measuring device 12 Reaction liquid storage tank 13 Caustic soda detoxification device 14 Exhaust gas pipe 15 Exhaust gas pipe 16 Gas phase section 17 Liquid phase section

Claims

1. 1. A method for producing a halogen oxyacid, comprising the steps of: continuously supplying an organic alkali solution and a halogen from one end of a reaction tube to the other end thereof, causing a liquid phase portion and a gas phase portion to be alternately and repeatedly present in a transfer passage of the reaction tube, and performing gas-liquid mixing of the organic alkali solution and the halogen in the liquid phase portion and / or the gas phase portion.

2. 2. The method for producing a halogen oxyacid according to claim 1, wherein a ratio of a volume flow rate of the halogen to a volume flow rate of the organic alkaline solution supplied to the reaction tube is 1 to 50.

3. 3. The method for producing a halogen oxyacid according to claim 1, wherein the reaction tube is extended in an axial direction while rotating around an axis extending from one end to the other end.

4. 3. The method for producing a halogen oxyacid according to claim 1, wherein the reaction tube is disposed so as to extend in a substantially horizontal direction.

5. 3. The method for producing a halogen oxyacid according to claim 1, wherein the reaction tube is formed in a spiral shape with a direction extending from one end to the other end as an axis, the axis being a spiral axis.

6. 3. The method for producing a halogen oxygen acid according to claim 1, wherein the reaction tube is a reaction tube containing a fluororesin.

7. 3. The method for producing a halogen oxyacid according to claim 1, wherein the reaction tube has an average inner diameter of 5 mm or more.

8. 1. An apparatus for producing a halogen oxyacid, comprising: a reaction tube which extends in an axial direction while rotating around an axis extending from one end to the other end of the reaction tube, the reaction tube being arranged so that the axis extends in a substantially horizontal direction, an organic alkali solution and a halogen are continuously supplied from the one end to the other end of the reaction tube, a liquid phase portion and a gas phase portion are alternately and repeatedly present in a transfer passage of the reaction tube, and the organic alkali solution and the halogen are gas-liquid mixed in the liquid phase portion and / or the gas phase portion.

9. 9. The apparatus for producing a halogen oxyacid according to claim 8, further comprising a means for supplying the organic alkaline solution and the halogen to the reaction tube in a ratio of a volumetric flow rate of the halogen to a volumetric flow rate of the organic alkaline solution of 1 to 50.

10. 10. The apparatus for producing a halogen oxyacid according to claim 8 or 9, wherein the reaction tube is a reaction tube formed in a spiral shape, and the spiral axis of the reaction tube is disposed to extend in a substantially horizontal direction.

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

12. 10. The apparatus for producing a halogen oxygen acid according to claim 8 or 9, wherein the reaction tube has an average inner diameter of 5 mm or more.

13. 10. The apparatus for producing a halogen oxygen acid according to claim 8 or 9, wherein the reaction tube is configured so that the organic alkaline solution has a residence time of 5 seconds to 30 minutes.