Aqueous solution having hypochlorous acid as main component

Abstract

To provide a solution having hypochlorous acid with improved storage stability as a main component.SOLUTION: The present invention discloses an aqueous solution having hypochlorous acid as a main component in which 40 mol% or more of the total sum of chlorine in the aqueous solution is chlorine of hypochlorous acid: particularly, an aqueous solution having hypochlorous acid as a main component in which 40 mol% or more of the total sum of chlorine in the aqueous solution is chlorine of hypochlorous acid, in which the total sum of alkali metal ions and alkaline earth metal ions is less than 1 mEq / L, and in which the total sum of negative ions in the aqueous solution other than hypochlorous acid is less than 10 mg / L, and which suppress metal corrosion.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous solution mainly composed of hypochlorous acid having excellent stability.

Background Art

[0002] Conventionally, as one of the chlorine-based halogen drugs, sodium hypochlorite exhibits an immediate bactericidal effect against bacteria at very low concentrations, and is also the most reliable disinfectant in terms of its effect against viruses such as HIV and HBV. It is widely used in various fields such as public health, food, and medicine for disinfection and sterilization in daily life. In particular, as the most common example, viruses such as norovirus and caliciviruses such as SLV (sapovirus) and rotavirus, which do not have an envelope, cannot be expected to be sterilized by alcohol disinfection, and disinfection and sterilization using hypochlorous acid are the first choice. Specifically, an aqueous solution containing sodium hypochlorite is used in the form of a spray or the like for disinfection and sterilization of various articles and environments such as clothing, tableware, glass containers, plastic containers, etc. in homes and medical sites. Furthermore, a powder agent is also used for sterilization of water supply and drainage and pools. In addition, sodium hypochlorite can be used for finger disinfection at very low concentrations in the form of an aqueous solution or a wet tissue impregnated with the aqueous solution. However, an aqueous solution of sodium hypochlorite obtained by dissolving sodium hypochlorite salt in water is strongly alkaline, and its diluted solution is also alkaline. Therefore, when used for finger disinfection, it causes rough hands (Patent Document 1).

[0003] On the other hand, hypochlorous acid produced by electrolysis using sodium chloride or the like is said to have a bactericidal and antiviral effect more than 80 times stronger than sodium hypochlorite. Such hypochlorous acid water shows acidity, different from the alkaline aqueous solution of sodium hypochlorite, and corrosion of metals and the like is likely to occur due to a low pH. Also, under acidic conditions, the amount of chloride ions increases, and chlorine gas and hydrogen chloride gas are likely to be generated, and hypochlorous acid decomposes, resulting in a problem that the displayed concentration falls below the set value within a short period. In addition, when the chlorine or salt content is high, the corrosion of metals is promoted.

[0004] In contrast, Patent Document 2 describes using an electrolytic cell of a two-diaphragm three-chamber type in which an anode chamber, a cathode chamber, and an intermediate chamber containing an electrolytic solution provided between the anode chamber and the cathode chamber are separated by diaphragms respectively to produce hypochlorous acid water substantially free of salts.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the method of Patent Document 2, when trying to increase the hypochlorous acid concentration, the pH decreases, resulting in an aqueous solution with a high total chlorine ion content, and there is a problem that the hypochlorous acid concentration decreases during storage.

[0007] Therefore, an object of the present invention is to provide an aqueous solution mainly composed of hypochlorous acid with better storage stability.

Means for Solving the Problems

[0008] As a result of the inventors' study on the above problems, it has been found that in an aqueous solution mainly composed of hypochlorous acid, by making 40 mol% or more of the total chlorine in the aqueous solution be the chlorine of hypochlorous acid, an aqueous solution mainly composed of more stable hypochlorous acid can be provided, and the present invention has been completed.

[0009] That is, the present invention provides: [1] An aqueous solution mainly composed of hypochlorous acid, wherein 40 mol% or more, preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more of the total chlorine in the aqueous solution is the chlorine of hypochlorous acid. [2] The total amount of alkali metal ions and alkaline earth metal ions is less than 1 mEq / L, preferably 0.8 mEq / L or less, more preferably not contained, the aqueous solution described in [1] above, [3] The aqueous solution described in [1] or [2] above, wherein the aqueous solution is electrolyzed water, [4] An aqueous solution obtained by adding an alkaline substance to the aqueous solution described in any one of [1] to [3] above to adjust the pH to 5.0 to 7.0, preferably 5.8 to 6.5, [5] The aqueous solution described in any one of [1] to [3] above, which is used after adding an alkaline substance to adjust the pH to 5.0 to 7.0, preferably 5.8 to 6.5, [6] The aqueous solution described in any one of [1] to [5] above, which is used after adding NaCl to adjust the osmotic pressure to 150 to 400 mOsm / L, preferably 150 to 350 mOsm / L, more preferably 220 to 300 mOsm / L, [7] A method for using the aqueous solution described in any one of [1] to [5] above, (i) Before use, adding an alkaline substance to adjust the pH to 5.0 to 7.0, preferably 5.8 to 6.5, and / or (ii) Before use, adding NaCl to adjust the osmotic pressure to 150 to 400 mOsm / L, preferably 150 to 350 mOsm / L, more preferably 220 to 300 mOsm / L The method for use including [8] Anions (e.g., Cl - , BrO3 - , SO4 2- , NO3 - etc.) contained in the aqueous solution other than hypochlorous acid have a total amount of less than 10 mg / L, the aqueous solution described in any one of [1] to [6] above, and [9] Chloride ions other than hypochlorous acid contained in the aqueous solution are less than 9 mg / L, and the total amount of anions (e.g., BrO3 - , SO4 2- , NO3 - etc.) in the aqueous solution other than chloride ions is 1 mg / L or less, and the pH is 5.0 to 7.0, the aqueous solution described in any one of [1] to [6] above relates to.

Advantages of the Invention

[0010] According to the present invention, in an aqueous solution mainly composed of hypochlorous acid, by setting 40 mol% or more of the total chlorine in the aqueous solution to be the chlorine of hypochlorous acid, an aqueous solution mainly composed of hypochlorous acid with more excellent storage stability can be provided.

Embodiments for Carrying Out the Invention

[0011] (Aqueous solution mainly composed of hypochlorous acid) According to Embodiment 1 of the present invention, an aqueous solution mainly composed of hypochlorous acid is characterized in that 40 mol% or more of the total chlorine in the aqueous solution is the chlorine of hypochlorous acid. This is indicated by the ratio of the molar amount of chlorine derived from hypochlorous acid with the total molar equivalent of components containing chlorine atoms in the aqueous solution being 100 mol% as the amount of hypochlorous acid in the aqueous solution. Thereby, even when HCl is contained in the aqueous solution, the amount of HCl does not exceed 60 mol% of the total chlorine in the aqueous solution, the pH of the aqueous solution can be made as close to neutral as possible, and it is considered that an aqueous solution mainly composed of hypochlorous acid with excellent storage stability can be obtained. Further, such an aqueous solution also has a low concern for metal corrosion and resin deterioration.

[0012] In this specification, "ppm" (mg / kg) used as the unit of concentration is used as a replacement for mg / L unless otherwise specified.

[0013] In the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1, 40 mol% or more of the total chlorine in the aqueous solution is chlorine of hypochlorous acid, that is, chlorine derived from hypochlorous acid. 50 mol% or more is preferable, 60 mol% or more is more preferable, 70 mol% or more is further preferable, 80 mol% or more is particularly preferable, and 90 mol% or more is most preferable. When the total amount of chlorine in the aqueous solution is large, chlorine gas is likely to be generated. For example, in the case where the aqueous solution is electrolyzed water, if the ratio of chlorine derived from hypochlorous acid to the total chlorine in the aqueous solution is less than 40 mol%, the ratio of hydrogen chloride increases, and damages such as irritation and corrosion caused by hydrogen chloride tend to increase. Corrosion of a metal means that the metal combines with metal ions, chlorine, bases (hydroxyl group, nitrate group, sulfate group, etc.), oxygen, etc., and occurs when the charge in the metal is taken away and it ionizes and falls off.

[0014] In the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1, "mainly composed of hypochlorous acid" means containing hypochlorous acid as a typical component other than water as a solvent, and does not mean that hypochlorous acid occupies most of the constituent components or that hypochlorous acid is the most abundant component among the components other than water. Therefore, as long as it does not adversely affect its disinfection and sterilization functions and the storage stability which is the effect of the present invention, other components, particularly components containing chlorine and components for adjusting pH, etc. may be included in addition to water and hypochlorous acid as the main components. For example, it can contain HCl. On the other hand, in conventional hypochlorous acid water, the content of undissolved sodium chloride and hydrogen chloride which is a pH component is large, and the ratio of hypochlorous acid is lower than that of the solution according to Embodiment 1.

[0015] When preparing the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1, it is preferable to use pure water, purified water, ion-exchanged water, etc. in order to suppress the mixing of unplanned components such as metal ions and organic substances contained in tap water.

[0016] In the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1, it is preferable to contain as little alkali metal ions and alkaline earth metal ions as possible. Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably less than 1 mEq / L, more preferably 0.8 mEq / L or less, and even more preferably 0.5 mEq / L or less. By setting the total amount of alkali metal ions and alkaline earth metal ions to less than 1 mEq / L, the generation of chlorine gas is suppressed, and the stability tends to increase. In other words, by minimizing the content of alkali metal ions and alkaline earth metal ions, which are counterions of chlorine, the generation of hydrogen chloride gas and the decomposition (deactivation) of hypochlorous acid can be suppressed. When such an aqueous solution is sprayed indoors, since the hydrogen chloride and the salt concentration are low, it is possible to keep the corrosion, especially the influence on electronic substrates, low.

[0017] The alkali metal ions and alkaline earth metal ions contained for pH adjustment if necessary are not particularly limited, and they can be added in the form of salts respectively. Examples of such salts of alkali metal ions include salts of sodium (Na) or potassium (K), and examples of salts of alkaline earth metal ions include salts of magnesium (Mg) or calcium (Ca). On the other hand, salts of rubidium (Rb) and osmium (Os) are preferably not used because they have been pointed out to be carcinogenic.

[0018] In the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1, the concentration of chlorides other than hypochlorous acid in the aqueous solution is preferably less than 1 mmol / L, more preferably 0.9 mmol / L or less, and even more preferably 0.4 mmol / L or less.

[0019] The aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 is preferably electrolyzed water, specifically, electrolyzed water mainly composed of hypochlorous acid obtained by performing electrolysis using hydrochloric acid or sodium chloride as a raw material is preferable.

[0020] The pH of the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 is preferably 2.7 or more, more preferably 3.2 or more, still more preferably 3.5 or more, and particularly preferably 5.8 or more. By setting the pH of the aqueous solution mainly composed of hypochlorous acid to 2.7 or more, the corrosiveness is reduced, and it tends to be usable for various applications. In particular, when using an aqueous solution mainly composed of hypochlorous acid in a humidifier, an air purifier, etc., since there is concern about corrosion and deterioration of the parts used in the device, the pH is preferably 3.2 or more. By setting the pH to 3.2 or more, the generation of chlorine gas (hydrogen chloride gas) can be more suppressed. Also, it is preferable that the pH of the aqueous solution mainly composed of hypochlorous acid is 5.8 or more and 6.5 or less. Thereby, the irritation to mucous membranes etc. is reduced, and at the same time, it conforms to the drinking water standard.

[0021] The aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 can be used for various applications due to its characteristics of not being too low in pH and having strong bactericidal and antiviral power. For example, it can be widely used in various fields such as public health like daily disinfection and sterilization, food, and medical care. It can be suitably used for disinfection, sterilization / antisepsis of various articles and environments such as clothes, tableware, glass containers, plastic containers, etc. in homes and medical sites. In particular, it is suitably used for cleaning and sterilization of the skin such as finger washing (hand washing and sterilization), and sterilization of spaces. In particular, in an embodiment that does not contain salt and is not too low in pH, there is less concern about corrosion. In tap water, fungi such as mold may generate in the water storage tank and spread the generated bacteria. Also, since it contains hypochlorous acid with a high bactericidal effect, it is possible to maintain the hygiene level not only of the device but also of the space. Therefore, it is preferable to use it instead of tap water in humidifiers, air purifiers, etc.

[0022] The aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 can be prepared by various methods. For example, first, in the above-described two-diaphragm three-chamber electrolytic cell, electrolysis is performed using an aqueous sodium chloride solution as the electrolyte to obtain acidic hypochlorous acid water obtained in the anode chamber. At this time, in the electrolysis of sodium chloride and water, usually, chlorine migrates to the anode and sodium migrates to the cathode. The migrated chlorine reacts with water to generate hydrogen chloride (HCl) and hypochlorous acid (HClO), and oxygen gas is generated. At the cathode, sodium reacts with water to generate sodium hydroxide, and hydrogen gas is generated. In the reaction of sodium chloride and water, as shown in the following equation, the stoichiometric ratio of the generation of hypochlorous acid and hydrogen chloride does not exceed 1:1, so the generation ratio of hypochlorous acid does not exceed hydrogen chloride. 2NaCl + H2O → 2NaOH + HCl + HClO Next, the obtained acidic hypochlorous acid water is electrolyzed again to convert hydrogen chloride into hypochlorous acid, and the ratio of hypochlorous acid to hydrochloric acid can be increased. By performing the treatment of increasing the ratio of hypochlorous acid to hydrochloric acid, the pH can be simultaneously shifted to the neutral side. In order to obtain the desired ratio of hypochlorous acid to hydrochloric acid and the desired pH, this treatment (electrolysis of hypochlorous acid water) can be repeated the necessary number of times.

[0023] According to Embodiment 2 of the present invention, an alkaline substance is added to the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 of the present invention to adjust the pH to 5.0 to 7.0. Since the dissociation constant of hypochlorous acid is 7.5, by setting the pH to 7.0 or less, the proportion of undissociated hypochlorous acid in the aqueous solution exceeds 50% (by setting the pH to 6.5 or less, the proportion of undissociated hypochlorous acid in the aqueous solution becomes 90% or more), and higher bactericidal performance can be exhibited. Also, by setting the pH to 5.8 or more, it conforms to the standards for drinking water. In Embodiment 2, it is more preferable to set the pH to 5.8 to 6.5. Here, as the alkaline substance, various pH adjusters can be used. Specifically, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydrogen carbonate, magnesium hydrogen carbonate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium citrate, potassium citrate, calcium citrate or magnesium citrate, and their aqueous solutions can be mentioned. Among them, sodium hydroxide and its aqueous solution are particularly preferably used.

[0024] Since the pH of the aqueous solution according to Embodiment 2 is 5 to 7, which is neutral to weakly acidic, it is close to the pH of the skin, and irritation caused by acids and itching caused by alkalis are drastically reduced. Also, by not tilting towards the alkaline side, the generation of trihalomethanes can be suppressed. When sprayed indoors, since the hydrogen chloride and the salt concentration are low, it is possible to keep the influence on corrosion, especially on electronic substrates, low. In addition to the uses of the aqueous solution according to Embodiment 1, it can be used for more various uses. For example, it is particularly suitable for skin cleaning and disinfection such as finger washing (hand washing and disinfection), space disinfection, disinfection of utensils, etc., and disinfection of pressure sores.

[0025] According to Embodiment 3 of the present invention, the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 of the present invention is characterized in that, before use, an alkaline substance is added to adjust the pH to 5.0 to 7.0. Since the dissociation constant of hypochlorous acid is 7.5, by setting the pH to 7.0 or less, the proportion of undissociated hypochlorous acid in the aqueous solution exceeds 50% (by setting the pH to 6.5 or less, the proportion of undissociated hypochlorous acid in the aqueous solution becomes 90% or more), and higher bactericidal performance can be exhibited. Also, by setting the pH to 5.0 or more, it conforms to the standards for drinking water. In Embodiment 3, it is more preferable that the pH is set to 5.8 to 6.5. Here, as the alkaline substance, various pH adjusters can be used. Specifically, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydrogen carbonate, magnesium hydrogen carbonate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium citrate, potassium citrate, calcium citrate or magnesium citrate, and their aqueous solutions can be mentioned. Among them, since sodium hydroxide and its aqueous solution become sodium chloride after the neutralization reaction, they are particularly preferably used in terms of the impact on the living body.

[0026] According to Embodiment 4 of the present invention, the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 of the present invention is characterized in that, before use, NaCl is added to adjust the osmotic pressure to 150 to 400 mOsm / L. The aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 of the present invention described above is preferably in an embodiment that contains as little salt as possible. For this reason, when the osmotic pressure is different from that of physiological saline, for example, when used for medical purposes such as wound cleaning, there is a risk of damaging red blood cells due to the difference in osmotic pressure when touching the blood, and it is necessary to adjust the osmotic pressure before use. The osmotic pressure is preferably adjusted so as not to cause hemolysis, more preferably adjusted to 150 to 350 mOsm / L, and even more preferably adjusted to 220 to 300 mOsm / L. When a large amount of NaCl is administered, chlorine gas (Cl2) is likely to be generated. Therefore, due to chemical equilibrium, the decomposition of hypochlorous acid is promoted and the inactivation (deterioration) rate becomes faster. For this reason, it is preferable to mix the chloride immediately before use.

[0027] According to Embodiment 5 of the present invention, the aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 of the present invention is characterized in that, before use, an alkaline substance and NaCl are added to adjust the pH to 5.0 to 7.0 and the osmotic pressure to 150 to 400 mOsm / L. When a large amount of chloride such as HCl or NaCl is administered to the generated hypochlorous acid water, chlorine gas (Cl2) is likely to be generated. Therefore, due to chemical equilibrium, the decomposition of hypochlorous acid is promoted. For this reason, it is preferable to mix the chloride immediately before use. Therefore, the alkaline substance and NaCl may be added at the same timing, or they can be added separately with a time interval. However, when adding them separately with a time interval, it is preferable to add the alkaline substance first.

[0028] According to Embodiment 6 of the present invention, an aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 of the present invention is added with (i) an alkaline substance before use to adjust the pH to 5.0 to 7.0, preferably 5.8 to 6.5, and / or (ii) NaCl is added before use to adjust the osmotic pressure to 150 to 400 mOsm / L, preferably 150 to 350 mOsm / L, more preferably 220 to 300 mOsm / L. The alkaline substance to be used, the mode of addition, and the effects of this method of use are as described in the above Embodiments 3 to 5.

[0029] In Embodiments 3 to 6 of the present invention, "before use" is not particularly limited, but for example, it means from one week before use to immediately before use, preferably immediately before use to one day before use, and more preferably within 8 hours from the perspective of the inactivation rate.

[0030] (Ready-to-mix formulation) Regarding the pre-use mixing of the alkaline substance and NaCl in Embodiments 3 to 5 of the present invention, it can be realized by various methods using commercially available NaCl and alkaline substances. For example, (A) an aqueous solution mainly composed of hypochlorous acid according to Embodiment 1 of the present invention described above (also referred to as solution (A)) is combined with (B) an alkaline substance (also referred to as agent (B)) and / or (C) an agent containing NaCl (also referred to as agent (C)) to form a kit, which can also be provided as a ready-to-mix formulation.

[0031] In the ready-to-mix formulation, various pH adjusters can be used as the alkaline substance of agent (B). Specifically, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, magnesium bicarbonate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium citrate, potassium citrate, calcium citrate or magnesium citrate, and their aqueous solutions can be mentioned.

[0032] In a ready-to-mix preparation, the agent containing sodium chloride in agent (C) can contain, in addition to sodium chloride, another isotonic agent. The isotonic agents that can be used are not particularly limited, and examples include sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydrogen carbonate, magnesium hydrogen carbonate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium citrate, potassium citrate, calcium citrate, or magnesium citrate.

[0033] The ready-to-mix preparation can also be in the form of a kit in which liquid (A) and agent (B) and / or agent (C) are each enclosed in separate containers, but it is preferably a multi-chamber container preparation in which liquid (A) and agent (B) are respectively accommodated in a first chamber and a second chamber in a multi-chamber container having at least two chambers partitioned by communicable isolation means. Such multi-chamber containers are preferably plastic double-bag type containers such as those used in two-liquid ready-to-mix dialysis solutions, for example made of polypropylene, or kit products with double-headed needles such as those used in ready-to-dissolve infusion sets.

[0034] The aqueous solution mainly containing hypochlorous acid according to Embodiments 4 to 5 of the present invention and the above-mentioned ready-to-mix preparation can be used to wash, sterilize, or disinfect wounds that come into contact with blood such as those caused by surgical or non-surgical means, or can be introduced into the lungs by a nebulizer to sterilize the lungs. Specifically, it includes surgeries such as general surgery, endoscopic surgery, robot-assisted laparoscopic surgery, oral surgery, graft surgery, implant surgery, transplant surgery, cauterization, cutting, radiation, chemotherapy, burns, cuts, abrasions, scratches, rashes, ulcers, puncture wounds, pressure sores, and combinations thereof, and is preferably used for applications such as infection control and keloid countermeasures.

[0035] In this specification, the matters described in the above Embodiments 1 to 6 are applicable to other embodiments as well, as long as they do not conflict with each other.

[0036] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not intended to be limited to these examples. Note that the aqueous solution mainly composed of hypochlorous acid obtained in the present invention can be stored frozen.

Example

[0037] Example 1 Using an aqueous sodium chloride solution as an electrolyte, electrolysis was carried out in a two-membrane three-compartment electrolytic cell to obtain strongly acidic hypochlorous acid water from the anode side. The obtained strongly acidic hypochlorous acid water was re-electrolyzed to convert hydrogen chloride into hypochlorous acid, and an aqueous solution mainly composed of hypochlorous acid with an increased ratio of hypochlorous acid to hydrochloric acid was obtained. The concentration of hypochlorous acid in the obtained aqueous solution mainly composed of hypochlorous acid was measured using an absorptiometer (AQ-102, manufactured by Shibata Chemical Co., Ltd.), and the total amount of chlorine was converted from the hypochlorous acid concentration and pH. The pH was measured using a multi-water quality meter (MM-60, manufactured by Toa DKK Corporation).

[0038] Comparative Example 1 An aqueous solution mainly composed of hypochlorous acid was obtained in the same manner as in Example 1 except that the re-electrolysis treatment was not performed. The concentration of hypochlorous acid, the total amount of chlorine, and other physical properties of the obtained aqueous solution mainly composed of hypochlorous acid were obtained in the same manner as in Example 1. The results are shown in Table 1.

[0039] Comparative Example 2 Using hydrochloric acid as an electrolyte, electrolysis was carried out in a diaphragm-free electrolytic cell and diluted with water to obtain an aqueous solution mainly composed of hypochlorous acid. The concentration of hypochlorous acid, the total amount of chlorine, and other physical properties of the obtained aqueous solution mainly composed of hypochlorous acid were obtained in the same manner as in Example 1. The results are shown in Table 1.

[0040]

Table 1

[0041] From Table 1, in Example 1, the pH increased compared to Comparative Examples 1 and 2, the ratio of hypochlorous acid to hydrochloric acid increased, and the chloride ion concentration in the aqueous solution decreased relatively. It can be seen that an aqueous solution mainly composed of hypochlorous acid with excellent storage stability was obtained. The amounts of chlorine in the hypochlorous acid of Example 1, Comparative Example 1, and Comparative Example 2 were approximately 47 mol%, approximately 18 mol%, and approximately 36 mol% with respect to the total amount of chlorine in the aqueous solution, respectively.

[0042] Example 2, Comparative Examples 3 and 4 Sodium hydroxide was added to 1 L of the aqueous solution mainly composed of hypochlorous acid obtained in Example 1, Comparative Example 1, and Comparative Example 2, and the pH was adjusted to 6.5. In Example 2, after adjusting the pH, chlorides other than hypochlorous acid were reduced by filtration treatment with a filtration membrane. The physical properties of the obtained aqueous solution are shown in Table 2.

[0043] [Table 2]

[0044] From Table 2, in Example 2, even when the pH was 6.5, the sodium ion concentration was suppressed to a low range of 0.70 mEq / L, and an aqueous solution mainly composed of hypochlorous acid with good stability and suppressed corrosive action on metals and the like was obtained compared to Comparative Examples 3 and 4.

[0045] Example 3 An aqueous solution mainly composed of hypochlorous acid was obtained from an aqueous sodium chloride solution in the same manner as in Example 1. The concentration of hypochlorous acid, the total amount of chlorine, and other physical properties of the obtained aqueous solution mainly composed of hypochlorous acid were measured in the same manner as in Example 1. The results are shown in Table 3.

[0046] Example 4 An aqueous solution mainly composed of hypochlorous acid was obtained in the same manner as in Example 1 except that re-electrolysis was repeated again. The concentration of hypochlorous acid, the total amount of chlorine, and other physical properties of the obtained aqueous solution mainly composed of hypochlorous acid were measured in the same manner as in Example 1. The results are shown in Table 3.

[0047]

Table 3

[0048] From Table 3, in Example 3, the ratio of hypochlorous acid to hydrochloric acid further increased, and in Example 4, the ratio of hypochlorous acid to hydrochloric acid increased even more. Since the chloride ion concentration in the aqueous solution decreased relatively, it can be seen that an aqueous solution mainly composed of hypochlorous acid with excellent storage stability was obtained. The amounts of chlorine in hypochlorous acid in Examples 3 and 4 were about 59 mol% and about 75 mol%, respectively, with respect to the total amount of chlorine in the aqueous solution.

Claims

[Claim 1] An aqueous solution in which 40 mol % or more of the total chlorine in the aqueous solution is chlorine from hypochlorous acid, which is the main component.

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