JP7600275B2 - Composition for producing hypochlorous acid water, hypochlorous acid water, and method for producing hypochlorous acid water - Google Patents

Description

The present invention relates to a composition for producing hypochlorous acid water and a method for producing hypochlorous acid water, and in particular to a composition for producing hypochlorous acid water formed as a solid such as a powder, and a method for producing hypochlorous acid water using the solid composition for producing hypochlorous acid water. Furthermore, the present invention relates to hypochlorous acid water that can maintain the sterilization effect of the produced hypochlorous acid water for a long period even in an indoor environment, and a composition for producing hypochlorous acid water that can produce the same.

Conventional hypochlorous acid water was produced by electrolyzing salted water using a dedicated generator, or by mixing a 6% or 12% sodium hypochlorite solution with a pH adjuster such as hydrochloric acid, citric acid, acetic acid, or carbon dioxide to adjust the acidic to neutral. Of these, mixing with carbon dioxide does not cause an excessive drop in pH, so there is little risk of an accident due to the generation of chlorine gas, but with other pH adjusters, if the pH is lowered too much, chlorine gas may be generated, resulting in fatal accidents. In particular, pH adjusters that cause oxidation-reduction reactions are highly dangerous because, when used in large quantities, they can drop to a pH of 4 or less (especially dangerous when the pH is 3 or less), which generates chlorine gas.

The disinfecting effect (or dissociation) of hypochlorous acid depends on the hydrogen ion exponent (pH) of hypochlorous acid. At pH 5, most of it exists as HOCl, but as the pH increases, HOCl decreases and ^ClO- increases, and at around pH 7.5, HOCl and ^ClO- each account for 50%. On the other hand, when the pH leans toward the acid side and becomes smaller than 4, HOCl generates chlorine molecules (chlorine gas, _Cl2 ), and the chlorine in the water (hypochlorous acid HOCl) changes form to _Cl2 , HOCl, and ^ClO- depending on the pH, and its reactivity also changes. _Cl2 has the highest disinfecting effect (reactivity), followed by HOCl and ^ClO- , but it was necessary to avoid the generation of harmful _Cl2 (gas).

Therefore, in Patent Document 1 (JP Patent Publication 9-108681 A), when electrolysis is performed using chloride salt and hydrochloric acid as a pH adjuster, very delicate adjustment of the pH of the electrolytic solution is required, and since hydrochloric acid is a dangerous substance, not everyone is able to adjust the pH of the electrolytic solution. In light of this, Patent Document 1 proposes an electrolytic solution for generating electrolytic hypochlorous acid sterilizing water that contains chloride salt for generating hypochlorous acid sterilizing water and phosphate and/or condensed phosphate as a pH adjuster.

Furthermore, Patent Document 2 (JP Patent Publication No. 2002-363017) proposes a disinfectant containing hypochlorous acid water, with a hypochlorous acid concentration of 1 to 1000 ppm and a pH in the range of 4.0 to 8.0, which contains a pH buffer solution, in order to solve the problems of insufficient disinfection effect of disinfectants, large variation in disinfection effect, and short-lasting disinfection effect, and to obtain a disinfectant that is easy to handle and easy to manufacture and does not have the drawback of corroding machines.

Japanese Patent Application Publication No. 9-108681 JP 2002-363017 A

As mentioned above, Patent Document 1 proposes using phosphate as a pH adjuster to avoid the generation of hydrochloric acid. However, what is proposed in this document is an electrolytic solution used to generate hypochlorous acid-containing sterilizing water by non-diaphragm electrolysis, and after mixing with phosphate, electrolysis must be performed in a non-diaphragm electrolytic cell.

In addition, in the above-mentioned Patent Document 2, a pH buffer solution is used to improve the durability of the disinfection effect and solve the problem of machine corrosion. However, in this document, a sodium hypochlorite aqueous solution is mixed to prepare a mixed aqueous solution consisting of a pH buffer solution, and liquids are mixed together. Therefore, a problem of dissociation of hypochlorous acid in the sodium hypochlorite aqueous solution occurs, making it difficult to handle. In addition, in this document, in order to solve problems such as the durability of the disinfection effect and corrosion of machines, a mixed aqueous solution consisting of two or more compounds, such as sodium citrate and sodium hydroxide, or acetic acid and sodium acetate, is used as the pH buffer solution.

Therefore, one aspect of the present invention aims to provide a composition for producing hypochlorous acid water and related technologies that can produce hypochlorous acid water without using special equipment such as a diaphragm-less electrolytic cell or without performing processes such as electrolysis, and that can improve the storage stability and ease of handling by using a solid, including a powder.

Furthermore, the problem of another embodiment is as follows. The hypochlorous acid water provided so far cannot be said to have sufficient durability of the sterilizing effect. Therefore, the problem of providing hypochlorous acid water with further improved durability of the sterilizing effect and a composition for producing hypochlorous acid water capable of producing the same, or providing hypochlorous acid water capable of maintaining the sterilizing effect for a long period of time in an indoor environment without storing in a light-shielding environment and a composition for producing hypochlorous acid water capable of producing the same, is another problem different from the problem of one embodiment of the present invention described above.

Furthermore, the object of another embodiment is as follows: To provide hypochlorous acid water and a composition for producing hypochlorous acid water capable of producing the same, which improves the problem of metal corrosivity, does not cause white precipitation after application, or improves the problem of precipitates in hypochlorous acid water, and which is a different object from the object of one embodiment of the present invention described above.

One aspect of the present invention provides a composition for producing hypochlorous acid water, hypochlorous acid water, and a method for producing hypochlorous acid water, which enables the production of hypochlorous acid water using a solid such as a powder.

That is, in one aspect of the present invention, there is provided a composition for producing hypochlorous acid water, the composition comprising a hypochlorite or a hydrate thereof in the form of a powder or other solid, and a pH adjuster in the form of a powder or other solid.

The hypochlorite or its hydrate and the pH adjuster are both solids in the form of powder, granules, or pellets under normal temperature and pressure. Considering that these solids are quickly dissolved in water to produce hypochlorous acid water, it is desirable that they have a small particle size, for example, a particle size of 1.0 mm or less, particularly 0.1 mm or less. The hypochlorite or its hydrate (for example, calcium hypochlorite) may have a particle size of 3.0 mm or less, or 2.0 mm or less. The pH adjuster (for example, potassium dihydrogen phosphate) may have a particle size of 3.0 mm or less, or 2.0 mm or less. It is preferable to make both particles 1.0 mm or less in particle size, as they are easily dissolved in water. In addition, the hypochlorite or its hydrate and the pH adjuster can be stored separately, or they can be stored in a mixed state. The particle size in this specification may be determined by a sieve. For example, when the particle size is set to 1.0 mm or less, the above-mentioned hypochlorite or its hydrate and pH adjuster in powder form that can pass through a sieve with a maximum mesh width of 1.0 mm are prepared, that is, a composition for producing hypochlorous acid water is prepared. In addition, when the composition for producing hypochlorous acid water is aggregated, if the particle size is 3.0 mm or less after disintegration (disintegration), the composition for producing hypochlorous acid water is considered to satisfy the condition of a particle size of 3.0 mm or less in this specification. The disintegration may be performed by a known method, and a known classification device may be used as long as it does not cause deterioration of the above-mentioned hypochlorite or its hydrate and pH adjuster.

In the composition for producing hypochlorous acid water according to one embodiment of the present invention, it is preferable that the hypochlorite or its hydrate is calcium hypochlorite or sodium hypochlorite pentahydrate, and the pH adjuster is potassium dihydrogen phosphate.

In one embodiment of the present invention, hypochlorous acid water is produced by dissolving the composition for producing hypochlorous acid water according to the above embodiment of the present invention in water. Since the composition for producing hypochlorous acid water according to one embodiment of the present invention is a solid such as a powder, it can be stored for a long period of time and hypochlorous acid water can be easily produced in a short time when needed.

It is desirable that the hypochlorous acid water has a residual chlorine concentration reduction rate of 40% or less, particularly 10% or less, after 30 days of storage in a dark, room temperature environment. The hypochlorous acid water can be produced by dissolving the hypochlorite or its hydrate made of the above-mentioned powder or other solid and the pH adjuster made of the powder or other solid in water before the other is completely dissolved in water, or by dissolving them in water at the same time.

In one embodiment of the present invention, a method for producing hypochlorous acid water is provided to solve the above problems. That is, a method for producing hypochlorous acid water using a composition for producing hypochlorous acid water according to one embodiment of the present invention, in which either the hypochlorite or its hydrate or the pH adjuster is dissolved in water in its entirety, and then the other is dissolved in the water. In another embodiment of the present invention, a method for producing hypochlorous acid water using a composition for producing hypochlorous acid water according to one embodiment of the present invention, in which either the hypochlorite or its hydrate or the pH adjuster is dissolved in water before the other is dissolved in its entirety, or both are simultaneously dissolved in water.

Since the hypochlorite or its hydrate and the pH adjuster are both solids such as powder, granules, or pellets, they can be mixed and dissolved in water to dissolve both simultaneously. Alternatively, the hypochlorite or its hydrate can be added to water, and then the pH adjuster can be added and dissolved before the hypochlorite or its hydrate is completely dissolved, and then the pH adjuster can be added to water, and then the hypochlorite or its hydrate can be added and dissolved before the pH adjuster is completely dissolved. Alternatively, one or both of the components can be filled in a container, and water can be added to dissolve the components. The pH of the hypochlorous acid water may be 4 to 7 (or 4.5 to 6.5).

The first aspect of the present invention is
A composition for producing hypochlorous acid water that is solid,
The composition for producing hypochlorous acid water comprises a solid hypochlorite or a hydrate thereof and a solid pH adjuster.

A second aspect of the present invention is
The hypochlorite or its hydrate is calcium hypochlorite or sodium hypochlorite pentahydrate,
This is a composition for producing hypochlorous acid water described in the first aspect, wherein the pH adjuster is potassium dihydrogen phosphate.

A third aspect of the present invention is
This is a composition for producing hypochlorous acid water described in a second aspect, wherein the hypochlorite or a hydrate thereof is calcium hypochlorite.

A fourth aspect of the present invention is
The calcium hypochlorite has an effective chlorine concentration of 50% or more, or a dry effective chlorine concentration of more than 10%;
This is a composition for producing hypochlorous acid water described in the third aspect, wherein the purity of the potassium dihydrogen phosphate is 95% or more.

A fifth aspect of the present invention is
In the composition for producing hypochlorous acid water, the value of (weight of potassium dihydrogen phosphate)/(weight of calcium hypochlorite) is 1.5 or more and 100 or less, which is the composition for producing hypochlorous acid water described in the third or fourth embodiment.
The lower limit of the ratio (weight of potassium dihydrogen phosphate)/(weight of calcium hypochlorite) is, in order of preference, 4, 5, and 10. The upper limit of the ratio is, in order of preference, 70, 30, 25, 20, 15, and 12.

A sixth aspect of the present invention is
The calcium hypochlorite is a powder, and each particle constituting the powder has a particle size of 3.0 mm or less.
The composition for producing hypochlorous acid water according to any one of the third to fifth aspects, wherein the potassium dihydrogen phosphate is a powder and each particle constituting the powder has a particle size of 3.0 mm or less.

A seventh aspect of the present invention is
The composition for producing hypochlorous acid water is a composition for producing hypochlorous acid water described in any one of the first to sixth aspects, which exhibits a rust-preventing function when contacted with water.

The eighth aspect of the present invention is
The composition for producing hypochlorous acid water according to the seventh aspect, in which a series of steps of immersing carbon steel in a mixed solution (liquid temperature 22±2°C) of the composition for producing hypochlorous acid water and water for 15 minutes, rinsing the carbon steel with distilled water (22±2°C), and drying the carbon steel at 22±2°C for 45 minutes is repeated six times, the ratio of the area of rust to the area of the part of the carbon steel immersed in the mixed solution is 10 area % or less.

A ninth aspect of the present invention is
The hypochlorous acid water comprises the composition for producing hypochlorous acid water according to any one of the first to eighth embodiments and water.

A tenth aspect of the present invention is
The hypochlorite or hydrate thereof is calcium hypochlorite,
The pH adjuster is potassium dihydrogen phosphate;
The calcium hypochlorite has an effective chlorine concentration of 50% or more, or a dry effective chlorine concentration of more than 10%;
The purity of the potassium dihydrogen phosphate is 95% or more,
The amount of calcium hypochlorite added to the water is 10 mg/L or more and not more than a saturated concentration,
The amount of potassium dihydrogen phosphate added to the water is 50 mg/L or more and not exceeding a saturation concentration,
The hypochlorous acid water according to the ninth embodiment has a value of (amount of potassium dihydrogen phosphate added)/(amount of calcium hypochlorite added) of 1.5 or more and 100 or less.

An eleventh aspect of the present invention is
The hypochlorous acid water is the hypochlorous acid water described in the ninth or tenth aspect, which has an anti-rust function.

A twelfth aspect of the present invention is
The hypochlorous acid water according to an eleventh embodiment, in which a series of steps of immersing carbon steel in the hypochlorous acid water (liquid temperature 22±2°C) for 15 minutes, rinsing the carbon steel with distilled water (22±2°C), and drying the carbon steel at 22±2°C for 45 minutes is repeated six times, the ratio of the area of rust to the area of the portion of the carbon steel immersed in the mixed liquid is 10 area % or less.

A thirteenth aspect of the present invention is
A method for producing hypochlorous acid water, comprising contacting the composition for producing hypochlorous acid water according to any one of the first to eighth aspects with water.

A fourteenth aspect of the present invention is
The method for producing hypochlorous acid water according to the thirteenth embodiment, wherein the hypochlorite or its hydrate and the pH adjuster are dissolved in water before the other is dissolved in water, or both are dissolved in water simultaneously.

According to one embodiment of the present invention, hypochlorous acid water can be produced simply by dissolving the composition in water, making it possible to provide a composition for producing hypochlorous acid water that allows hypochlorous acid water to be produced without using special equipment such as a diaphragmless electrolytic cell or without performing processes such as electrolysis.

According to one embodiment of the present invention, the hypochlorite or its hydrate and the pH adjuster constituting the composition for producing hypochlorous acid water are both solids such as powders, so that a composition for producing hypochlorous acid water can be stored in a solid state for a long period of time and can be easily handled. The composition for producing hypochlorous acid water can be easily and quickly produced hypochlorous acid water by simply dissolving it in water as needed.

Furthermore, according to another embodiment of the present invention, by using calcium hypochlorite or sodium hypochlorite pentahydrate as the hypochlorite or its hydrate, using potassium dihydrogen phosphate as the pH adjuster, and dissolving either one before the other is completely dissolved in water, or by dissolving both in water simultaneously, it is possible to provide hypochlorous acid water with improved durability of the disinfecting effect, and a composition for producing hypochlorous acid water capable of producing the same.

FIG. 1 is a process diagram showing a process for producing hypochlorous acid water according to one embodiment of the present invention, and shows an embodiment in which hypochlorite or a hydrate thereof and a pH adjuster are each dissolved in water. FIG. 1 is a process diagram showing a process for producing hypochlorous acid water according to one embodiment of the present invention, and shows an embodiment in which hypochlorite or a hydrate thereof and a pH adjuster are combined by mixing or the like and then dissolved in water. 1 is a graph showing the results of Experimental Example 1, refrigerated (4° C.) and shaded. 1 is a graph showing the results of Experimental Example 1, the graph showing the results when light was shielded at room temperature (22±1° C.). 1 is a graph showing the results of Experimental Example 1, the graph showing the results under fluorescent light at room temperature (2,300 lx for 24 hours/day). 1 is a graph showing the results of Experimental Example 1, refrigerated (4° C.) and shaded. 1 is a graph showing the results of Experimental Example 1, the graph showing the results when light was shielded at room temperature (22±1° C.). 1 is a graph showing the results of Experimental Example 1, the graph showing the results under fluorescent light at room temperature (2,300 lx for 24 hours/day). 1 is a graph showing the results of Experimental Example 1, specifically, the results of Sample 4. 1 is a graph showing the results of Experimental Example 1, specifically, the results of Sample 5. 1 is a graph showing the results of Experimental Example 1, specifically, the results of Sample 6. 1 is a graph showing the results of Experimental Example 1, specifically, the results of Sample 4. 1 is a graph showing the results of Experimental Example 1, specifically, the results of Sample 5 and Sample 6. 1 is a graph showing the results of Experimental Example 2, refrigerated (4° C.) and shaded. 1 is a graph showing the results of Experimental Example 2, the graph showing the results when light was shielded at room temperature (22±1° C.). 1 is a graph showing the results of Experimental Example 2, the graph showing the results under fluorescent light at room temperature (2,300 lx for 24 hours/day). 1 is a graph showing the results of Experimental Example 2, refrigerated (4° C.) and shaded. 1 is a graph showing the results of Experimental Example 2, the graph showing the results when light was shielded at room temperature (22±1° C.). 1 is a graph showing the results of Experimental Example 2, the graph showing the results under fluorescent light at room temperature (2,300 lx for 24 hours/day). 13 is a graph showing the results of Experimental Example 3, in which powdered calcium hypochlorite was used. 13 is a graph showing the results of Experimental Example 3, in which an aqueous sodium hypochlorite solution was used. 1 is a graph showing the results of Experimental Example 4, in which the vertical axis indicates the available chlorine concentration and the horizontal axis indicates the number of days of storage. 1 is a graph showing the results of Experimental Example 4, in which the vertical axis indicates pH and the horizontal axis indicates the number of days of storage. 13 is a photograph showing the results of Experimental Example 5. 13 shows the results of X-ray analysis in Experimental Example 5. 1 is a graph showing the results of Experimental Example 6, in which the vertical axis indicates the available chlorine concentration and the horizontal axis indicates the number of days of storage. 1 is a graph showing the results of Experimental Example 6, in which the vertical axis indicates pH and the horizontal axis indicates the number of days of storage. 1 is a graph showing the results of Experimental Example 6, in which the vertical axis indicates the available chlorine concentration and the horizontal axis indicates the number of days of storage. 1 is a graph showing the results of Experimental Example 6, in which the vertical axis indicates pH and the horizontal axis indicates the number of days of storage. 13 is a photograph showing the results of Experimental Example 6. 13 is a photograph showing the results of Experimental Example 9. 13 is a photograph showing the results of Experimental Example 10. 1 is a photograph showing the results of Experimental Example 11, which is an example without serum. 13 is a photograph showing the results of Experimental Example 11, which is an example in which serum is present.

Hereinafter, a composition for producing hypochlorous acid water according to one embodiment of the present invention will be specifically described with reference to the drawings. In this specification, "to" refers to a value equal to or greater than a specified value and equal to or less than a specified value. In this specification, "mg/L" may be expressed as "ppm". However, unless otherwise specified, ppm in this specification refers to the effective chlorine concentration.

Figure 1 is a process diagram showing a manufacturing process for hypochlorous acid water according to one embodiment of the present invention. In this first embodiment, hypochlorite or its hydrate and a pH adjuster are composed of powders or other solids, and Figure 1A shows an embodiment in which hypochlorite or its hydrate and a pH adjuster are each dissolved in water, and Figure 1B shows an embodiment in which hypochlorite or its hydrate and a pH adjuster are combined by mixing or the like and then dissolved in water. In addition, although not shown, it is also possible to fill a container with either or both of the components and add water to dissolve them.

"About the composition for producing hypochlorous acid water"
As the hypochlorite, calcium hypochlorite powder can be used, and as the hydrate of hypochlorite, sodium hypochlorite pentahydrate powder can be used. As the pH adjuster, potassium dihydrogen phosphate powder can be used. It is preferable to use these hypochlorite or its hydrate and the pH adjuster in solid form such as powder, granule, or pellet (including tablet form), especially powder or granule. That is, since the composition for producing hypochlorous acid water according to one embodiment of the present invention is formed using a solid such as powder, the hypochlorite or its hydrate and the pH adjuster can be stored for a long period of time separately or in a mixed state. And, when used, hypochlorous acid water can be easily and quickly produced by simply dissolving in water as shown in FIG. 1.

The hypochlorite or its hydrate may be in the form of a powder or other solid, and may be in the form of an alkali metal salt such as sodium, potassium, or lithium, an alkaline earth metal salt such as calcium or magnesium, or a zinc salt. These may be used alone or in combination of two or more.

Hereafter, unless otherwise specified in this specification, calcium hypochlorite will be used as an example of hypochlorite.

The effective chlorine concentration of calcium hypochlorite according to one embodiment of the present invention may be 70% or more (this is used in each experimental example described in this specification) (preferably 75% or more). In this specification, the effective chlorine concentration may be referred to as purity. The composition (remainder) of calcium hypochlorite that does not contribute to the effective chlorine concentration may be a composition containing calcium (e.g., calcium salt). A specific example of calcium hypochlorite according to one embodiment of the present invention is high-grade bleaching powder. High-grade bleaching powder can also be used as a food additive and is a highly safe compound. However, the present invention is not limited to the above-mentioned effective chlorine concentration. For example, the effective chlorine concentration of calcium hypochlorite according to one embodiment of the present invention may be 50% or more. In one embodiment of the present invention, calcium hypochlorite that is dry and has an effective chlorine concentration (in other words, the content of effective chlorine when water is removed) of more than 10% may be used.

In this specification, available chlorine concentration is synonymous with residual chlorine concentration.

The pH adjuster may be in the form of a powder or other solid, and may be trisodium phosphate, tripotassium phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, etc. In addition, hydroxides of alkali metals, hydroxides of alkaline earth metals, inorganic acids or their salts, organic acids or their salts, etc. may be used. Examples of hydroxides of alkali metals and hydroxides of alkaline earth metals include sodium hydroxide, potassium hydroxide, calcium hydroxide, etc. Examples of inorganic acids or their salts include hydrochloric acid, sodium sulfate, sodium nitrate, sodium chloride, sodium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, magnesium sulfate, magnesium nitrate, magnesium chloride, magnesium carbonate, sodium polyphosphate, etc. Examples of organic acids or their salts include saturated dibasic acids or their salts such as phthalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, etc., and unsaturated dibasic acids or their salts such as fumaric acid, maleic acid, etc. In particular, it is preferable that the pH adjuster is a phosphate, especially potassium dihydrogen phosphate, and it is also preferable that the pH adjuster is in the form of a powder.

The inventors have investigated the suitability of each of the compounds, including those listed above, as a pH adjuster in one embodiment of the present invention.

As a result, it was found that, among sodium salts, sodium dihydrogen phosphate (NaH ₂ PO ₄ ), acidic sodium pyrophosphate (Na ₂ H ₂ P ₂ O ₇ ), and acidic sodium metaphosphate ((Na _x H _y PO ₃ ) _n ) were suitable.
Of the potassium salts, potassium dihydrogen phosphate (KH ₂ PO ₄ ) was suitable.
The reason why they were suitable is that when the hypochlorous acid water producing composition is mixed with water to obtain hypochlorous acid water, the pH of the hypochlorous acid water is appropriate (acidic) and the buffering ability is exerted, so that the pH fluctuation is small (in summary, the pH adjustment ability is high). In addition, the pH adjustment ability of potassium dihydrogen phosphate was particularly high.
In addition, when sodium salt reacts with hypochlorous acid, a salt (NaCl) is generated by chlorine and sodium, which may cause rust or corrosion, whereas potassium dihydrogen phosphate does not have such a risk. Therefore, potassium dihydrogen phosphate is particularly preferable as a pH adjuster.
Furthermore, when ammonium salts were also examined as a pH adjuster, it was found that monoammonium phosphate ( _{NH4H2PO4 )} had a high pH adjusting ability, but since ammonium salts form chloramine, which is combined chlorine rather than free chlorine, after reacting with _hypochlorous acid, this significantly reduces the bactericidal ability.
Furthermore, calcium salts were also examined as pH adjusters, and it was found that monocalcium phosphate (Ca(H ₂ PO ₄ ) _{2.H 2} O) had a high pH adjusting ability, but calcium salts are inherently less soluble in water than other salts.
Therefore, potassium dihydrogen phosphate remains the most preferred pH adjuster.

Hereafter, unless otherwise specified in this specification, potassium dihydrogen phosphate will be used as an example of a pH adjuster.

The purity of potassium dihydrogen phosphate according to one embodiment of the present invention may be 95% or more (preferably 98% or more or 99% or more (used in each experimental example described in this specification)). The composition (remainder) of potassium dihydrogen phosphate that does not contribute to the purity of potassium dihydrogen phosphate may be a composition containing at least one of potassium and phosphorus (for example, at least one of a potassium salt other than potassium dihydrogen phosphate, a phosphorus salt, and a potassium phosphorus salt). Potassium dihydrogen phosphate can also be used as a food additive and is a highly safe compound.

The amount of the pH adjuster used can be, for example, 100 parts by weight or more, preferably 300 parts by weight or more, per 100 parts by weight of calcium hypochlorite or sodium hypochlorite pentahydrate. In addition, when potassium dihydrogen phosphate is used as the pH adjuster, even if the powder of the pH adjuster is added in an amount greater than the required amount or even exceeding the saturated concentration, the pH of the hypochlorous acid water will only drop to about 4.5, and no matter how much is added, the pH will not reach 4.0 or less (especially 3.0 or less), at which chlorine gas will be generated. Therefore, from the perspective of the problem of chlorine gas generation during the production of hypochlorous acid water, it is not necessary to specify the upper limit of the amount of the pH adjuster to be mixed.

In one embodiment of the composition for producing hypochlorous acid water according to the present invention, the value of (weight of potassium dihydrogen phosphate)/(weight of calcium hypochlorite) may be 1.5 or more and 100 or less. The lower limit values are 4, 5, and 10, in order of preference. The upper limit values are 70, 30, 25, 20, 15, 12, and 10, in order of preference.

In this specification, "consisting of" refers solely to the fact that the main components of the solid hypochlorous acid water producing composition according to one embodiment of the present invention are composed of a hypochlorite or a hydrate thereof (e.g., the above-mentioned calcium hypochlorite) and a pH adjuster (e.g., the above-mentioned potassium dihydrogen phosphate).
To explain this example, the composition other than the calcium hypochlorite or the potassium dihydrogen phosphate (for convenience of explanation, also referred to as "impurities") may be a composition containing an element not contained in calcium hypochlorite or potassium dihydrogen phosphate (i.e., an element other than Ca, Cl, O, H, P, and K).
In this specification, "consisting of" means that when the entire composition for producing hypochlorous acid water is 100 parts by weight, the total amount of the calcium hypochlorite (effective chlorine concentration of 70% or more) and the potassium dihydrogen phosphate (purity of 95% or more) is 95 parts by weight or more (preferably 98 parts by weight or more, more preferably 99 parts by weight or more, even more preferably 99.9 parts by weight or more, and particularly preferably 100 parts by weight).
That is, in the composition for producing hypochlorous acid water according to one embodiment of the present invention, the impurities are less than 5 parts by weight (preferably less than 2 parts by weight, more preferably less than 1 part by weight, even more preferably less than 0.1 parts by weight, and particularly preferably 0 parts by weight). In each experimental example shown below, this corresponds to a value of at least 99 parts by weight or more (impurities are less than 1 part by weight).
The calcium hypochlorite referred to here has an effective chlorine concentration of 70% or more (preferably 75% or more). The remainder may be a composition containing calcium (e.g., a calcium salt). The remainder, which is less than 5% (preferably less than 2%, less than 1%) of the total weight of the calcium hypochlorite, may be the above-mentioned impurities.
The potassium dihydrogen phosphate has a purity of 95% or more (preferably 98% or more or 99% or more). The remainder of less than 5% (preferably less than 2%, less than 1%) may be the impurities, and one example is a composition in which the remainder contains at least one of potassium and phosphorus (for example, at least one of a potassium salt other than potassium dihydrogen phosphate, a phosphorus salt, and a potassium phosphorus salt).
A composition for producing hypochlorous acid water according to one embodiment of the present invention consists of (or consists only of) solid calcium hypochlorite having the above-mentioned effective chlorine concentration and solid potassium dihydrogen phosphate having the above-mentioned purity.

The hypochlorous acid water produced by the above-mentioned hypochlorous acid water producing composition can have an effective chlorine concentration of 20 ppm to 5000 ppm and a pH range of 4 to 7 (or pH 4.5 to 6.5). Therefore, about 30 mg to 10 g of calcium hypochlorite can be used per liter of water, and 0.1 g to 220 g of potassium dihydrogen phosphate can be used, depending on the concentration of calcium hypochlorite. If a higher chlorine concentration is required, it is possible to use up to 210 g of calcium hypochlorite (270,000 ppm) per liter of water. However, precipitation becomes noticeable at concentrations of 2000 ppm or more.

The amount of calcium hypochlorite added to water (in other words, the amount mixed with water) may be 10 mg/L or more and the saturated concentration or less (for example, 1000 mg/L or less). The lower limit is preferably 160 mg/L. The upper limit is preferably 480 mg/L.

The amount of potassium dihydrogen phosphate added to water (in other words, the amount mixed with water) may be 50 mg/L or more and the saturated concentration or less (for example, 20,000 mg/L or less). The lower limit is preferably 1,000 mg/L. The upper limit is, in order of preference, 10,000 mg/L and 4,000 mg/L.

Furthermore, when using sodium hypochlorite pentahydrate, the effective chlorine concentration is around 40%, so the effective chlorine concentration can be 20 ppm to 5000 ppm, and the pH can be in the range of 4 to 7 (or pH 4.5 to 6.5). Approximately 35 mg to 12 g of calcium hypochlorite can be used per liter of water, and 0.1 g to 220 g of potassium dihydrogen phosphate can be used, depending on the sodium concentration of hypochlorite. When using sodium hypochlorite pentahydrate (powder), it is possible to handle up to 300,000 ppm (approximately 2,500 g/L, depending on the product).

The hypochlorite or its hydrate and the pH adjuster constituting the composition for producing the above-mentioned hypochlorous acid water are solids such as powders, and therefore can be stored in a stable state for a long period of time.

That is, calcium hypochlorite (available chlorine concentration listed in the catalogue is around 70%) can be stored in a dry place away from direct sunlight and fire. If stored in such an environment, it can be stored for over a year without the available chlorine concentration decreasing. Sodium hypochlorite pentahydrate (available chlorine concentration listed in the catalogue is around 40%) can be stored stably for a year in a cool, dark place at 7°C or below. However, it needs to be refrigerated, so a device for this (refrigerator) is required. Potassium dihydrogen phosphate can also be stored for long periods of time, on the order of years, if the container is kept sealed, away from direct sunlight, and stored in a well-ventilated place.

For example, when two powdered components, calcium hypochlorite and potassium dihydrogen phosphate, were mixed together and stored in a non-light-shielding microtube at room temperature (approximately 18°C to 22°C) under indoor light (12 hours per day under fluorescent lamps with an average of approximately 2,300 lux), for 30 days to a year, the pH and chlorine concentration of hypochlorous acid water produced by dissolving the mixture were equivalent to those produced from the two components immediately after production. In addition, when the two components were stored in the microtube for a week at 50°C, the pH was equivalent, but the chlorine concentration had decreased by approximately 5%. When the two components were stored for a week at 70°C, the pH was equivalent, but the chlorine concentration had decreased by approximately 30%.

In addition, when the hypochlorite or its hydrate and the pH adjuster are powders, the storage method can be to store the two components (solids such as powders) of the hypochlorite or its hydrate and the pH adjuster separately, or to mix the two components into one and store them. When storing the two components separately, a certain amount of each solid can be stored in a bottle or bag. In this case, the user needs to measure the amount used each time or in advance. Each component can also be packaged in individual portions for the amount used. In this case, the components can be packaged in a light-shielding or non-light-shielding paper or resin (such as polypropylene) film drug package, or in a light-shielding or non-light-shielding plastic container such as a microtube, and the packaged components can be placed in a light-shielding or non-light-shielding container or bag. In that case, the composition for producing hypochlorous acid water may be called a hypochlorous acid water production composition set consisting of a solid hypochlorite or its hydrate and a solid pH adjuster.

When storing two ingredients together, the ingredients can be mixed in advance and a relatively large amount stored in a bottle or bag. In this case, the user needs to measure the amount to be used each time or in advance. The ingredients can also be mixed in advance or not, and packaged separately for the amount to be used. In this case, the required amounts of each ingredient can be packaged together in a single light-shielding or non-light-shielding paper or resin film package, or the required amounts can be packaged together in a single light-shielding or non-light-shielding plastic container such as a microtube. The packages can then be stored in a light-shielding or non-light-shielding container or bag.

"How to make hypochlorous acid water"
The above-mentioned hypochlorous acid water producing composition can be dissolved in water to produce hypochlorous acid water. In particular, the components constituting the hypochlorous acid water producing composition according to one embodiment of the present invention (hypochlorite or its hydrate and pH adjuster) are all solids such as powders, and hypochlorous acid water with any chlorine concentration and any pH (pH 4 to 7 (or pH 4.5 to 6.5)) can be easily produced by simply dissolving them in water. Moreover, by adjusting the amount of sodium hypochlorite pentahydrate powder or calcium hypochlorite powder used, high-concentration hypochlorous acid water can also be produced.

In this regard, previous methods of producing hypochlorous acid water involved electrolyzing a liquid (sodium hypochlorite) with a liquid (hydrochloric acid, acetic acid), a liquid (sodium hypochlorite) with a gas (carbon dioxide), a liquid (sodium hypochlorite) with a solid (citric acid), or a liquid (water) with a solid (table salt). All of these methods required dedicated equipment and could not be generated on-site.

That is, if gas is used, a tank is required, and if liquid is used, it must be stored in a light-shielding container as a liquid. In addition, in the conventional liquid-liquid and liquid-solid manufacturing methods, if the manufacturing method and the compounding amount in the manufacturing process are incorrect, the pH will drop too much (pH 3 or less) and chlorine gas will be generated, which is dangerous. On the other hand, the manufacturing method using carbon dioxide gas has the advantage that the pH does not drop more than necessary, but it requires a carbon dioxide gas tank and a dedicated generator. In addition, the generated product foams, so it is not suitable for transportation. In the manufacturing method of electrolyzing liquid (water) and solid (table salt), the raw materials are cheap and the production is easy, but there are problems such as deterioration of the dedicated generator and its electrodes and ion exchange membrane, and the concentration only rising to about several tens of ppm.

In contrast, in the manufacturing method according to one embodiment of the present invention, two types of powders (solids) are dissolved in water and diluted as necessary, so hypochlorous acid water can be produced without using a special and expensive generator. In addition, solids such as powders do not require as much storage space as liquids, and unless they require refrigeration or dark storage, they can be stored for a long period of time (several years) while avoiding direct sunlight. Therefore, it is possible to produce a hypochlorous acid water production composition that is advantageous in terms of storage, handling, and production of hypochlorous acid water.

The hypochlorite or its hydrate and the pH adjuster can be dissolved in water separately or simultaneously in a solid state such as powder, or can be mixed or dissolved in a solution in which one of them is dissolved. When both are dissolved in water in a solid state (powder or granules), one can be dissolved after the other, or the other can be dissolved before all of one is dissolved in water, or both can be dissolved in water at the same time. In particular, when both are dissolved in water in a solid state (powder or granules), they can be mixed before dissolving, or they can not be mixed before dissolving. In addition, the method of dissolving each component can be to put each powdery component in a container and then add water, or to put each powdery component in water after adding water. When dissolving each component in water, it can be dissolved while stirring with a stirrer or the like, or it can be dissolved by any method such as inversion mixing or shaking mixing.
In this specification, simultaneous dissolution refers to dissolving the hypochlorite or a hydrate thereof and the pH adjuster by any of the following methods.
- One solid (e.g. powder) is added to water, followed immediately by the other solid (e.g. powder), and the dissolution processes take place simultaneously.
- Mix both solids (e.g. both powders) and add them to water at the same time to dissolve.
In this specification, dissolution of two powders (so to speak, non-simultaneous dissolution) refers to dissolving one solid (e.g., powder) in water completely or nearly completely (at least half or more of the total amount) and then dissolving the other solid (e.g., powder) in water.

In order to dissolve the hypochlorite or its hydrate and the pH adjuster in water at the same time, both must be in a solid state (powder or granules). Also, since both are solids such as powders, each solid such as powder can be stored in its optimal state and the required amounts can be added simultaneously to dissolve and use. The hypochlorite or its hydrate and the pH adjuster can be stored separately from each other, or the two components can be mixed in advance and then supplemented.

By dissolving the hypochlorite or its hydrate and the pH adjuster simultaneously, or by dissolving one of them before the other is completely dissolved in water, the production time can be shortened and the durability of the sterilization effect can be improved. That is, the hypochlorous acid water produced by the production method according to one embodiment of the present invention can have a reduction in residual chlorine concentration of 40% or less, particularly 10% or less, after 30 days of storage in a dark, room temperature environment.

On the other hand, when either hypochlorite or its hydrate or a pH adjuster was dissolved in water and then the other was dissolved, the pH fluctuated by about 10% and the residual chlorine concentration decreased by nearly 50% after 30 days of storage in a colorless, transparent, non-light-shielding plastic bottle at room temperature (about 18°C to 22°C) exposed to indoor light (12 hours per day under fluorescent lights with an average of about 2,300 lux), whereas when hypochlorite or its hydrate and the pH adjuster were dissolved simultaneously, or when the other was dissolved before either of them had completely dissolved in water, the pH fluctuated by about 5% and the residual chlorine concentration decreased by less than 5% after 30 days of storage in a colorless, transparent, non-light-shielding plastic bottle at room temperature under indoor light.

The hypochlorous acid water producing composition, which is composed of solid components such as powders, is used by dissolving it in water. It was found that the duration of the disinfecting effect of the hypochlorous acid water produced varies depending on the dissolving method of the hypochlorous acid water producing composition. Focusing on this dissolving method, the time and order of dissolving each component constituting the hypochlorous acid water producing composition, and the powder particle size of each component were examined. As a result, it was confirmed that it is desirable to dissolve most of each component constituting the hypochlorous acid water producing composition in water (tap water, etc.) within at least 10 seconds, and therefore it is desirable to make the particle size of each component 0.1 mm or less. Therefore, it is desirable that the hypochlorite or its hydrate and the pH adjuster constituting the hypochlorous acid water producing composition according to one embodiment of the present invention are powders with a particle size of 0.1 mm or less. In addition, in the case of a calcium hypochlorite solution whose pH is adjusted with potassium dihydrogen phosphate, the lower the pH, the less the chlorine concentration decreases over time. However, the present invention is not limited to this embodiment. For example, the particle size of the hypochlorite or its hydrate (one example is calcium hypochlorite) may be 3.0 mm or less, or 2.0 mm or less. The particle size of the pH adjuster (one example is potassium dihydrogen phosphate) may be 3.0 mm or less, or 2.0 mm or less.

"About hypochlorous acid water"
The hypochlorous acid water produced by the above-mentioned composition for producing hypochlorous acid water contains hypochlorous acid and has a pH adjusted to 4 to 7 (or pH 4.5 to 6.5), and the free chlorine immediately after production is almost equal to the residual chlorine concentration. This residual chlorine concentration can be set arbitrarily. In theory, it is possible to produce up to 120,000 to 160,000 ppm, which is the ratio (60 to 80%) of the effective chlorine concentration of the solubility limit of calcium hypochlorite (21 g/100 ml (25 ° C.)). For example, a high concentration hypochlorous acid water (stock solution) of about 1000 ppm to 2000 ppm may be prepared and stored at room temperature in the dark, and it may be diluted with tap water or distilled water as needed for use. In this case, the effective chlorine concentration of the hypochlorous acid water that becomes the stock solution decreases over time, depending on its concentration. For example, when hypochlorous acid water is stored in a dark environment at room temperature for two weeks, the effective chlorine concentration decreases by about 20% at 1000 ppm and by about 30% at 2000 ppm. Therefore, for such applications, it is necessary to prepare a stock solution in anticipation of the decrease in chlorine concentration.

For example, hypochlorous acid water (residual chlorine concentration: 200-300 ppm) in which calcium hypochlorite is dissolved in water and then the pH is adjusted with potassium dihydrogen phosphate, loses only about 5% of its effective chlorine concentration even when stored in a refrigerator for one month, and the pH also shows little change over time. In addition, when stored at room temperature and protected from light, the effective chlorine concentration decreases by about 20-30% after one month of storage, and the pH also shows little change over time. Furthermore, when exposed to light at room temperature (irradiated for 24 hours with a fluorescent lamp (UV 13-14 μW/cm ² ) of about 2300-2400 lux), the effective chlorine concentration decreases by 50-70% in one month, and the pH decreases by about 0.4 over time.

In the manufacturing method according to one embodiment of the present invention, in addition to hypochlorous acid, several by-products may be generated. That is, when a composition for producing hypochlorous acid water consisting of calcium hypochlorite and potassium dihydrogen phosphate is used, the precipitate may contain a small amount of CaHPO _{4.2H 2} O (analyzed by X-ray diffraction), HOCl, ClO ^- , K ⁺ , H ⁺ , PO ₄ ^3- in the solution, and very small amounts of KH ₂ PO ₄ and KCl. Also, when a composition for producing hypochlorous acid water consisting of sodium hypochlorite and potassium dihydrogen phosphate is used, no precipitate is generated, but the solution may contain very small amounts of NaH ₂ PO ₄ , KH ₂ PO ₄ , KCl, and NaCl in addition to HOCl, ClO ^- , Na ⁺ , K ⁺ , H ⁺ , PO ₄ ^3- . However, all of the products are approved as food additives. When calcium hypochlorite is used, it does not contain bromate, which is included as an impurity in the manufacturing process of sodium hypochlorite and increases during storage, causing problems as a cause of contamination.It also does not contain sodium and its compounds, which are believed to cause metal corrosion.

Also, if calcium hypochlorite is first completely dissolved in water and then potassium dihydrogen phosphate is added to adjust the pH, the solution is colorless and transparent and no precipitate is formed immediately after production, but after three hours a very small amount of precipitate forms, and the amount reaches a plateau after six hours (the amount of precipitate is very small, and the precipitate is calcium hydrogen phosphate dihydrate). On the other hand, if calcium hypochlorite and potassium dihydrogen phosphate are dissolved in water at the same time, a very small amount of precipitate (floating) forms immediately after mixing, but it does not increase significantly over time, and the amount of precipitate itself is equal to or less than if calcium hypochlorite is completely dissolved in water first and then potassium dihydrogen phosphate is added.

In the hypochlorous acid water producing composition according to one embodiment of the present invention, the hypochlorous acid water using potassium dihydrogen phosphate as a pH adjuster can significantly reduce the occurrence of rust on metals. That is, when a structure (dental cutting bur) made of carbon steel is immersed in a solution made from calcium hypochlorite whose pH is adjusted with potassium dihydrogen phosphate (immersed for 15 minutes, then washed with distilled water and naturally dried for 45 minutes six times), rust does not completely disappear. However, the amount of rust is extremely small. For example, the ratio of the area of rust to the area of the part of the carbon steel immersed in the solution is 10 area% or less, or even 5 area% or less, 4 area% or less, 3 area% or less, or 2 area% or less.

In contrast, rust occurs when the item is immersed in a calcium hypochlorite solution without the pH adjuster added, or in hypochlorous acid water that is currently available on the market. A small amount of this rust also occurs in 80% ethanol, and a similar amount of rust occurs when the item is immersed in distilled water (see Experimental Example 11 below for details).

In this specification, carbon steel may be low carbon steel with a carbon content of 0.02% to 0.25% by mass, medium carbon steel with a carbon content of 0.25% to 0.6% by mass, or high carbon steel with a carbon content of 0.6% to 2.14% by mass. Impurities may include about 0.03% by mass of sulfur, 0.01% by mass of phosphorus, and about 0.05% by mass of silicon. The balance is iron.

That is, the composition for producing hypochlorous acid water according to one embodiment of the present invention exhibits a rust-preventing function when it comes into contact with water. And, a mixture of the composition for producing hypochlorous acid water according to one embodiment of the present invention and water (hereinafter also referred to as "hypochlorous acid water according to one embodiment of the present invention") has a rust-preventing function. At first glance, it seems to go against the common technical knowledge of those skilled in the art that hypochlorous acid water has a rust-preventing function. On the other hand, as shown in Experimental Example 11 below, the composition for producing hypochlorous acid water according to one embodiment of the present invention exhibits a rust-preventing function when it comes into contact with water.

Moreover, as shown in the experimental examples below, the hypochlorous acid water according to one embodiment of the present invention changes less over time in both effective chlorine concentration and pH compared to examples other than the embodiment of the present invention. In other words, the hypochlorous acid water according to one embodiment of the present invention is less susceptible to deterioration. Therefore, the method for producing hypochlorous acid water according to one embodiment of the present invention has an aspect of providing anti-rust function to hypochlorous acid water, and an aspect of improving the ability to maintain the quality (specifically, pH and effective chlorine concentration) of hypochlorous acid water.

The mechanism behind the above effects, although speculative, is as follows:

"About the mechanism of effectiveness"
(Behavior of the composition for producing hypochlorous acid water when it comes into contact with water)
An example of a composition for producing hypochlorous acid water according to one embodiment of the present invention is composed of calcium hypochlorite and potassium dihydrogen phosphate. When calcium hypochlorite comes into contact with water, calcium hydroxide and hypochlorous acid are generated. The chemical reaction formula when calcium hypochlorite comes into contact with water is as follows.
Ca(ClO) ₂ +H ₂ O→Ca(OH) ₂ +HOCl...(1)

The hypochlorous acid water according to one embodiment of the present invention is acidic, and calcium hydroxide is ionized according to the following reaction formula.
Ca(OH) ₂ →Ca ²⁺ +2OH ^-... (2)

Hypochlorous acid (HOCl) exerts a bactericidal effect when it comes into contact with an object. However, depending on the situation, HOCl is decomposed into ions as shown in the following reaction formula, and the bactericidal effect gradually decreases.
HOCl→H ⁺ +ClO ^- (3)
Then, the hypochlorite ion (ClO ⁻ ) is decomposed into chloride ions and oxygen ions as follows.
ClO ^- +2e ^- →Cl ^- +O ² -...(4)

When potassium dihydrogen phosphate comes into contact with water, it is ionized as shown in the following reaction equation:
KH ₂ PO ₄ →K ⁺ +2H ⁺ +PO ₄ ³ -...(5)

(Rust or corrosion inhibition mechanism)
The mechanism by which rust or corrosion is inhibited is, simply put, that potassium dihydrogen phosphate acts as a precipitated film-type rust inhibitor.

To explain in order, the hypochlorous acid (HOCl) first exerts its sterilizing power on the surface of the object. This breaks down the organic matter attached to the surface of the object.

If no measures are taken, the hypochlorous acid will continue to act on the surface of the object even after the organic matter attached to the surface of the object has been decomposed, eroding the surface of the object. As a result, if no measures are taken, rust or corrosion will occur significantly.

On the other hand, the composition for producing hypochlorous acid water according to one embodiment of the present invention contains potassium dihydrogen phosphate. Therefore, after the organic matter attached to the surface of the object is decomposed by the hypochlorous acid, a calcium hydrogen phosphate (CaHPO ₄ ) film is formed on the surface of the sterilized object. The reaction formula is as follows:
Ca ²⁺ +H ⁺ +PO ₄ ^3- →CaHPO ₄ ↓ ・・・(6)
The calcium hydrogen phosphate may be a hydrate (see Experimental Example 5 below). For example, the coating may be formed of calcium hydrogen phosphate dihydrate ( _CaHPO4.2H2O ). In _{addition to calcium hydrogen phosphate, a coating composed of Ca(H2PO4)2.H2O may also be formed} .

In any case, precipitation occurs due to the above (2) and (5) and hydrogen ions in the hypochlorous acid water. The object to be sterilized is present in the hypochlorous acid water. As a result, phosphate (CaHPO ₄ ) accumulates on the surface of the object, resulting in the formation of a coating on the surface of the object. It is presumed that this coating inhibits the occurrence of rust or corrosion on the object.

(The mechanism by which hypochlorous acid water is less likely to deteriorate)
The mechanism by which hypochlorous acid water is resistant to deterioration is, simply put, that even if hypochlorous acid (HOCl) is decomposed due to deterioration, hypochlorous acid is significantly regenerated in hypochlorous acid water.

To explain step by step, the hypochlorous acid (HOCl) first exerts its germicidal properties on the surface of the target object.

However, as the bactericidal ability is exerted, as shown in (3) above, the hypochlorous acid (HOCl) is decomposed into hydrogen ions (H ⁺ ) and hypochlorous acid ions (ClO ⁻ ). Furthermore, as shown in (4) above, ClO ⁻ is decomposed into chlorine ions and oxygen ions. If no measures are taken, the hypochlorous acid remains decomposed, or even if the hypochlorous acid is regenerated by chemical equilibrium, the effective chlorine concentration decreases and/or the pH changes, that is, the degree of deterioration of the hypochlorous acid water is large.

On the other hand, the hypochlorous acid water according to one embodiment of the present invention is not easily deteriorated. The reason for this is presumably that the hypochlorous acid ion (ClO ⁻ ) in (3) and/or the chlorine ion and oxygen ion in (4) combine with hydrogen ions to regenerate hypochlorous acid (HOCl). The source of the hydrogen ions may be hydrogen ions generated when the hypochlorous acid (HOCl) is decomposed, or hydrogen ions remaining during the generation of calcium hydrogen phosphate (CaHPO ₄ ) constituting the coating described above (Mechanism of inhibiting rust or corrosion). The reaction formula for the regeneration of hypochlorous acid (HOCl) is as follows:
H ⁺ +ClO ^- → HOCl...(7)
H ⁺ +Cl ^- +O ^2- → HOCl...(8)

One of the factors that cause the above (8) and (9) is radicals. In more detail, when hypochlorous acid water is exposed to stimuli such as sunlight (particularly UV light) or high temperature, radicals are generated as follows.
HOCl→・OH+・Cl...(9)

Generally speaking, the above reaction (10) is a decomposition reaction of hypochlorous acid and is undesirable. However, in the technical idea of the present invention, this radical is actively utilized to regenerate hypochlorous acid (HOCl). The reaction formula is as follows:
HOCl+・OH → H ₂ O+・ClO ... (10)
HCl+・ClO→HOCl+・Cl...(11)

It is speculated that the technical idea of the present invention may take advantage of the decomposition of hypochlorous acid by taking advantage of the high reactivity of radicals to promote the regeneration of hypochlorous acid (HOCl).

It is also speculated that hypochlorous acid (HOCl) is regenerated via a different route (reaction formula). This is explained below.

When hypochlorous acid water deteriorates, chlorine ions are generated as shown in (4) above, resulting in hydrochloric acid (HCl). In addition, when hypochlorous acid water deteriorates, chlorate ions (ClO ₃ ⁻ ) are also generated, resulting in chloric acid (HClO ₃ ).

However, in the hypochlorous acid water according to one embodiment of the present invention, hydrochloric acid (HCl) and chloric acid (HClO ₃ ) combine with oxygen ions and hydrogen ions to return to hypochlorous acid. Therefore, the hypochlorous acid water according to one embodiment of the present invention is not easily deteriorated.

It is speculated that the above radicals are also involved in the regeneration of hypochlorous acid (HOCl) in this other route (reaction formula). In other words, it is speculated that even if hypochlorous acid is decomposed in another route (reaction formula), it is possible that the highly reactive radicals are used to their advantage to promote the regeneration of hypochlorous acid (HOCl).

The chemical reaction involved in the regeneration of hypochlorous acid (HOCl) is always in chemical equilibrium in the hypochlorous acid water. Therefore, the change in pH over time is significantly small, and the efficacy of hypochlorous acid remains almost unchanged.

All of the above mechanisms can be realized because when a solid hypochlorous acid water producing composition, which consists of a solid hypochlorite or its hydrate (specifically, calcium hypochlorite) and a solid pH adjuster (specifically, potassium dihydrogen phosphate), is dissolved in water, each of the above reactions occurs in an excellent balance.

Moreover, the above chemical equilibrium is most likely to be achieved when calcium hypochlorite and potassium dihydrogen phosphate are dissolved simultaneously (as seen in the comparison of the experimental results in each of the experimental examples below when they are dissolved simultaneously and when they are not).

The technical scope of the present invention is not limited to the above-described embodiments, but also includes forms in which various modifications and improvements are made within the scope that can derive specific effects obtained by the constituent elements of the invention and their combinations.

The following describes this experimental example. The technical scope of the present invention is not limited to the following experimental example. The term "water" used hereinafter refers to distilled water (DW). The term "(m) g/500 ml" indicates the amount of reagent (specifically calcium hypochlorite or potassium dihydrogen phosphate) added when the solvent distilled water (or sodium hypochlorite aqueous solution) in each experimental example is 500 mL.
Furthermore, unless otherwise specified, in the following experimental examples, calcium hypochlorite is a powder having a particle size of 3.0 mm or less, and potassium dihydrogen phosphate is a powder having a particle size of 3.0 mm or less.
In the following experimental examples, the amount of each reagent was determined so that the pH and ppm (available chlorine concentration) of each sample was achieved. The amount of each reagent listed for each sample (e.g., 4 g of potassium dihydrogen phosphate for sample 5) is merely a guideline.

In this experimental example, an experiment was conducted to confirm the properties of hypochlorite or its hydrate made of powder or other solid, and a pH adjuster made of powder or other solid. Note that the experimental results for sodium hypochlorite in the following experimental examples can be considered to be substantially the same as the experimental results for solid sodium hypochlorite pentahydrate containing powder, to the extent that does not contradict the purpose of each experiment.

[Experimental Example 1: Hypochlorous Acid Water Aging Test]
In this experimental example, the combination of hypochlorite and pH adjuster was changed to confirm the change in pH and residual chlorine concentration over time under different storage conditions.The components, storage conditions, and storage time of each sample tested are shown in Table 1 below, and the change in residual chlorine concentration over time is shown in Table 2 below.
"Components of each sample" refers to the presence or absence of phosphate. Specifically, it refers to Sample 4 (aqueous sodium hypochlorite solution) to which no phosphate was added and Sample 4, Sample 5 (calcium hypochlorite, pH 5.5 in aqueous solution) to which no phosphate was added and Sample 5, and Sample 6 (calcium hypochlorite, pH 6.0 in aqueous solution) to which no phosphate was added and Sample 6.
"Storage conditions" refers to room temperature or refrigeration, fluorescent light or dark.
"Storage time" refers to 0 to 60 days.
Room temperature is 22±2°C (21±2°C or 20±2°C are also acceptable. Unless otherwise specified, it refers to 22±2°C), and the amount of light emitted by the fluorescent lamp is 2300±100 lux (UV: 10±1 μW/ ^cm2 ). Room temperature in the dark refers to 22±1°C. In this experimental example, either the hypochlorite or the pH adjuster was dissolved in water, and then the other was dissolved.

In addition, in this experimental example, the changes in chlorine concentration and pH over time due to different storage conditions were confirmed for multiple hypochlorous acid solutions. The hypochlorous acid solution samples used in this experimental example are as follows:

Sample 1: "Electrolytic type (55 ppm)" used sodium hypochlorite as the hypochlorite. Specifically, it was generated from a generator (Fine Oxygen FOW-1000S6-D/G, First Ocean Co., Ltd., Kanagawa, Japan).
Sample 2: "Two-liquid (hydrochloric acid) mixture" used sodium hypochlorite as the hypochlorite. Specifically, the product name was Rena Water (Rena Fine Co., Ltd., Tokyo, Japan).
Sample 3-1: "carbonate mixed (130 ppm)" used sodium hypochlorite as the hypochlorite. Specifically, it was generated from a generator (KHM-1, Rena Fine Co., Ltd., Tokyo, Japan).
Sample 3-2: "carbonate mixed (240 ppm)" used sodium hypochlorite as the hypochlorite. Specifically, it was generated from a generator (KHM-1, Rena Fine Co., Ltd., Tokyo, Japan).
Sample 4: "Na hypochlorite + phosphate (250 ppm)" used sodium hypochlorite as the hypochlorite and potassium dihydrogen phosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., hereafter the same) as the pH adjuster. Specifically, sodium hypochlorite aqueous solution (concentration 6%) (product name PYURAX (registered trademark), manufactured by OYALAX Co., Ltd.) was diluted with distilled water (DW) to prepare 5 mL of sodium hypochlorite aqueous solution (250 ppm), to which 4 g of potassium dihydrogen phosphate was added.
Sample 5: "Ca hypochlorite + phosphate pH 6.0 (250 ppm)" Calcium hypochlorite was used as the hypochlorite, and potassium dihydrogen phosphate was used as the pH adjuster. Specifically, 200 mg of calcium hypochlorite and 4 g of potassium dihydrogen phosphate were dissolved in 500 mL of distilled water (DW). One of the components (Ca hypochlorite) was dissolved in water, and then the other (phosphate) was dissolved.
Sample 6: "Ca hypochlorite + phosphate pH 5.5 (250 ppm)" Calcium hypochlorite was used as the hypochlorite, and potassium dihydrogen phosphate was used as the pH adjuster. Specifically, 200 mg of calcium hypochlorite and 5 g of potassium dihydrogen phosphate were dissolved in 500 mL of distilled water (DW). One of the components (Ca hypochlorite) was dissolved in water, and then the other (phosphate) was dissolved.

The storage conditions were as follows: "refrigerated (4°C) protected from light" (storage in a refrigerated environment at 4°C), "room temperature protected from light (22±1°C) protected from light" (storage in a room temperature environment at 22±1°C), and "room temperature under fluorescent light (2,300 lx for 24 h/day)" (storage in a room temperature environment at 22±1°C and exposed to light at 2,300 lx for 24 hours/day.

The residual chlorine concentration was measured using an HI 96771C manufactured by Hanna Instruments Japan, and the pH was measured using a pH meter (LAQUAtwin (registered trademark) B-71X) manufactured by Horiba, Ltd. The results are shown in FIG.
The vertical axis of Figures 2A to 2C shows the ratio of the residual chlorine concentration to the available chlorine concentration on day 0, and the horizontal axis shows the number of days of storage. Figure 2A is a graph showing the results of Experimental Example 1, which is a graph showing the results of refrigeration (4°C) and shading. Figure 2B is a graph showing the results of Experimental Example 1, which is a graph showing the results of room temperature shading (22±1°C). Figure 2C is a graph showing the results of Experimental Example 1, which is a graph showing the results of room temperature under fluorescent light (2,300 lx for 24 h/day).
The vertical axis of Figures 2D to 2F indicates pH, and the horizontal axis indicates the number of days of storage. Figure 2D is a graph showing the results of Experimental Example 1, which is a graph showing the results of refrigeration (4°C) and shading. Figure 2E is a graph showing the results of Experimental Example 1, which is a graph showing the results of shading at room temperature (22±1°C). Figure 2F is a graph showing the results of Experimental Example 1, which is a graph showing the results of under fluorescent light at room temperature (2,300 lx for 24 h/day).

FIG. 3 shows the change in chlorine concentration over time due to differences in storage conditions for each of the above samples 4 to 6.
The vertical axis of Figures 3A to 3C indicates the effective chlorine concentration, and the horizontal axis indicates the number of days of storage. Figure 3A is a graph showing the results of Experimental Example 1, which is a graph showing the results of Sample 4. Figure 3B is a graph showing the results of Experimental Example 1, which is a graph showing the results of Sample 5. Figure 3C is a graph showing the results of Experimental Example 1, which is a graph showing the results of Sample 6. ● indicates the effective chlorine concentration at the time of production, ◯ indicates the effective chlorine concentration when stored in a refrigerator (4°C) and protected from light, △ indicates the effective chlorine concentration when stored at room temperature (22°C) and protected from light, and □ indicates the effective chlorine concentration when stored under fluorescent light at room temperature (2,300 lx, 24 h/day).
FIG. 4 shows the change in pH over time depending on the storage conditions for Samples 4 to 6, as well as the change in pH over time for samples using sodium hypochlorite (aqueous solution) and calcium hypochlorite alone ("Phosphate (-)" in the figure).
The vertical axis of Figures 4A and 4B indicates pH, and the horizontal axis indicates the number of days of storage. Figure 4A is a graph showing the results of Experimental Example 1, which is a graph showing the results of Sample 4. Figure 4B is a graph showing the results of Experimental Example 1, which is a graph showing the results of Samples 5 and 6. Circles indicate pH when stored in a refrigerator (4°C) protected from light, triangles indicate pH when stored at room temperature (22°C) protected from light, and squares indicate pH when stored at room temperature under fluorescent light (2,300 lx, 24 h/day).

As a result of this experiment, it was confirmed that hypochlorous acid water produced from a hypochlorous acid water producing composition consisting of calcium hypochlorite and potassium dihydrogen phosphate, both of which are powders, deteriorates less over time (residual chlorine concentration and pH) under all storage conditions compared to other samples. It was also confirmed that hypochlorous acid water produced with a lower pH is more stable over time.

[Experimental Example 2: Hypochlorous Acid Water (Ca Hypochlorous Acid) Time-Course Test]
In this experimental example, in order to confirm the change in chlorine concentration and pH over time when powdered hypochlorite was used, the above samples 5 and 6, "Ca hypochlorite (160 mg/DW500 mL) (sample A)" in which calcium hypochlorite was dissolved alone in water, and "Na isocyanurate (sample B)" in which isocyanuric acid was dissolved in water (all 200 ppm) were stored under the above conditions of "refrigerated (4°C) light-shielded", "room temperature light-shielded (22±1°C) light-shielded", and "room temperature under fluorescent light (2300 lux for 24 h/day)". In this experiment, either the hypochlorite or the pH adjuster was dissolved in water, and then the other was dissolved. The results are shown in Table 3 and FIG. 5 below.
The vertical axis of Figures 5A to 5C shows the ratio of the residual chlorine concentration to the available chlorine concentration on day 0, and the horizontal axis shows the number of days of storage. Figure 5A is a graph showing the results of Experimental Example 2, which is a graph showing the results of refrigeration (4°C) and shading. Figure 5B is a graph showing the results of Experimental Example 2, which is a graph showing the results of shading at room temperature (22±1°C). Figure 5C is a graph showing the results of Experimental Example 2, which is a graph showing the results of under fluorescent light at room temperature (2,300 lx for 24 h/day).
The vertical axis of Figures 5D to 5F indicates pH, and the horizontal axis indicates the number of days of storage. Figure 5D is a graph showing the results of Experimental Example 2, refrigerated (4°C) and shaded. Figure 5E is a graph showing the results of Experimental Example 2, shaded at room temperature (22±1°C). Figure 5F is a graph showing the results of Experimental Example 2, shaded at room temperature (2,300 lx for 24 h/day). ◯ indicates the results of Sample A, ■ indicates the results of Sample 5, □ indicates the results of Sample 6, and ● indicates the results of Sample B.

[Experimental Example 3: pH Adjuster Amount Test]
In this experimental example, the change in pH due to the difference in the amount of powder pH adjuster (potassium dihydrogen phosphate) used relative to hypochlorite was confirmed. As hypochlorite, powder calcium hypochlorite (80-240 mg (100-300 ppm)) and solution sodium hypochlorite (0.84-2.52 ml (100-300 ppm)) were used, and potassium dihydrogen phosphate was added in amounts of 0 g, 0.5 g, 1.0 g, 2.0 g, 3.0 g, 4.0 g, and 5.0 g to each of the hypochlorite dissolved in 500 ml of distilled water. The results are shown in Table 4 and FIG. 6 below.
The vertical axis of Figures 6A and 6B indicates pH, and the horizontal axis indicates the amount (g) of potassium dihydrogen phosphate added to 500 mL of DW. Figure 6A is a graph showing the results of Experimental Example 3, in which powdered calcium hypochlorite was used. Figure 6B is a graph showing the results of Experimental Example 3, in which an aqueous sodium hypochlorite solution was used.

From the results of this experiment, it was confirmed that even if a large amount of phosphate (especially potassium dihydrogen phosphate) was added as a pH adjuster, the pH would not fall below the upper half of the 4 range. This means that even if the user makes a mistake in the amount of each component mixed, the pH will not fall below 4, at which point chlorine gas is generated, and therefore it is possible to create a composition for producing hypochlorous acid water that is extremely low in danger.

[Experimental Example 4: High Concentration Test]
In this experimental example, the changes in effective chlorine concentration and pH over time during storage in the "room temperature, light-shielded (22±1°C) light-shielded" environment in high-concentration hypochlorous acid water were confirmed. The samples used were as follows.

Sample 7: "Ca hypochlorite + phosphate (1000 ppm)" uses calcium hypochlorite as the hypochlorite, potassium dihydrogen phosphate as the pH adjuster, and the effective chlorine concentration is 1000 ppm. Specifically, 800 mg of calcium hypochlorite and 20 g of potassium dihydrogen phosphate were dissolved in 500 mL of distilled water (DW). Each component was dissolved simultaneously.
Sample 8: "Na hypochlorite + phosphate (1000 ppm)" uses sodium hypochlorite as hypochlorite, potassium dihydrogen phosphate as pH adjuster, and has an effective chlorine concentration of 1000 ppm. Specifically, 20 g of potassium dihydrogen phosphate was added to an aqueous solution of sodium hypochlorite (concentration 6%) (product name: PYURAX (registered trademark), manufactured by OYALAX Co., Ltd.) in which the effective chlorine concentration was adjusted to 1000 ppm.
Sample 9: "Na hypochlorite + phosphate (2000 ppm)" uses sodium hypochlorite as hypochlorite, potassium dihydrogen phosphate as pH adjuster, and has an effective chlorine concentration of 2000 ppm. Specifically, 40 g of potassium dihydrogen phosphate was added to an aqueous solution of sodium hypochlorite (concentration 6%) (product name PYURAX (registered trademark), manufactured by OYALAX Co., Ltd.) in which the effective chlorine concentration was adjusted to 2000 ppm.
Sample 10: "Na hypochlorite + phosphate (4000 ppm)" uses sodium hypochlorite as hypochlorite, potassium dihydrogen phosphate as pH adjuster, and has an effective chlorine concentration of 4000 ppm. Specifically, 80 g of potassium dihydrogen phosphate was added to an aqueous solution of sodium hypochlorite (concentration 6%) (product name PYURAX (registered trademark), manufactured by OYALAX Co., Ltd.) in which the effective chlorine concentration was adjusted to 4000 ppm.

The storage days and changes in available chlorine concentration and pH for each sample were confirmed, and the results are shown in Table 5 below and FIG.
7A is a graph showing the results of Experimental Example 4, with the vertical axis showing the effective chlorine concentration and the horizontal axis showing the number of days of storage. FIG. 7B is a graph showing the results of Experimental Example 4, with the vertical axis showing the pH and the horizontal axis showing the number of days of storage.

These results confirmed that when hypochlorous acid water is prepared using a composition for producing hypochlorous acid water, which uses hypochlorite salt and potassium dihydrogen phosphate as a pH adjuster, the residual chlorine concentration of 1000 ppm hardly drops at all after three days at room temperature in the dark.

[Experimental Example 5: Precipitation Test]
In this experimental example, the presence or absence of precipitation (by-products) in hypochlorous acid water prepared using powdered hypochlorite and powdered pH adjuster was confirmed, as well as the degree of precipitation.As hypochlorite, powdered calcium hypochlorite was used, and as powdered pH adjuster, phosphate (potassium dihydrogen phosphate) was used.Calcium hypochlorite was set to 220mg/500ml (residual chlorine concentration: about 280ppm), and the amount of phosphate added was set to 0mg/500ml, 1000mg/500ml, 2000mg/500ml, 2500mg/500ml, 3000mg/500ml, 3500mg/500ml, 4000mg/500ml, 4500mg/500ml and 5000mg/500ml, and the change in pH and precipitation were confirmed 1 hour, 3 hours, 1 day, 3 days, 1 week and 2 weeks after generation. The storage conditions were the above-mentioned "room temperature, protected from light (22±1° C.), non-protected from light." The results are shown in Table 6 and FIG.

Figure 8 also shows (A) the condition one hour after the addition of 100 mg of phosphate, (B) the condition one hour after the addition of 200 mg of phosphate, (C) the condition three days after the addition of 100 mg of phosphate, (D) the condition three days after the addition of 200 mg of phosphate, (E) the condition three days after the addition of 500 mg of phosphate, (F) the condition one week after the addition of 100 mg of phosphate, (G) the condition one week after the addition of 200 mg of phosphate, and (H) the condition one week after the addition of 500 mg of phosphate.

The precipitate was then subjected to component analysis by X-ray analysis. The sample precipitate was prepared by generating a large amount of hypochlorous acid water consisting of calcium hypochlorite and potassium dihydrogen phosphate with an effective chlorine concentration of 2500 ppm (pH 6) and collecting the precipitate. This was washed three times with distilled water, twice with acetone, and twice with ether, and then dried to obtain 6.843 g, which was used for X-ray analysis using a Rint-Ultima III manufactured by Rigaku Corporation. The results are shown in Figure 9.

As a result of this X-ray analysis, it was confirmed that the precipitate was calcium hydrogen phosphate dihydrate ( _CaHPO4.2H2O ). Furthermore, it was confirmed that this precipitate, calcium _{hydrogen phosphate} dihydrate ( _CaHPO4.2H2O ), is a food additive and therefore highly safe.

[Experimental Example 6: Manufacturing Method Test]
In this experimental example, the changes over time in the chlorine concentration and pH of the produced hypochlorous acid water due to differences in the production method, and the presence or absence and degree of precipitation (by-products) in the produced hypochlorous acid water were confirmed.

First, in order to confirm the difference depending on the timing of dissolving the hypochlorite and the pH adjuster, the following samples were prepared and the changes in the chlorine concentration and pH of the produced hypochlorous acid water over time were confirmed.
Sample 11: "1 Powder" was prepared by simultaneously dissolving 180 mg of powdered hypochlorite (calcium hypochlorite) and 2 g of powdered pH adjuster (potassium dihydrogen phosphate) in 500 mL of distilled water (DW).
Sample 12: "2 Powder" was prepared by dissolving 180 mg of hypochlorite (calcium hypochlorite) completely in 500 mL of distilled water (DW) and dissolving 2 g of a pH adjuster (potassium dihydrogen phosphate) in the solution.
Sample 13: "Na hypochlorite + HCl" was prepared by dissolving a pH adjuster (hydrochloric acid) in hypochlorite (aqueous sodium hypochlorite solution).

Each sample was filled into a 500 ml colorless, transparent, non-light-shielding PET bottle, and the changes in available chlorine concentration and pH over time were confirmed when the sample was stored in a normal indoor environment (18-22°C, exposed to an average of 300-400 lux fluorescent light for 12 hours per day). The results are shown in Figure 10.
Fig. 10A is a graph showing the results of Experimental Example 6, where the vertical axis indicates the effective chlorine concentration and the horizontal axis indicates the number of days of storage. Fig. 10B is a graph showing the results of Experimental Example 6, where the vertical axis indicates the pH and the horizontal axis indicates the number of days of storage.
The results and experimental conditions are summarized as follows.
(Performance of the composition for producing hypochlorous acid water and its confirmation conditions 1)
Powdered hypochlorite (calcium hypochlorite) and powdered pH adjuster (potassium dihydrogen phosphate) are dissolved simultaneously in 500 mL of distilled water (DW), and the same amount of 500 mL is filled into a colorless, transparent, non-light-shielding PET bottle. Even if the bottle is exposed to an average of 300 to 400 lux of fluorescent light for 12 hours per day at an ambient temperature of 20±2°C for 30 days, the decrease in effective chlorine concentration (in the case of an increase, the decrease is considered to be zero) is less than 2% (preferably less than 1%), and the change in pH (in most cases the decrease) is less than 4% (preferably less than 3%, more preferably less than 2%).

These experimental results confirmed that dissolving powdered hypochlorite (calcium hypochlorite) and powdered pH adjuster (potassium dihydrogen phosphate) in water at the same time is much more stable than dissolving each component separately. Therefore, it was confirmed that it is desirable to dissolve at least one of the hypochlorite and powdered pH adjuster components before the other component is completely dissolved.

In this experiment, the timing of dissolving each component of hypochlorite and pH adjuster was changed, and the change in residual chlorine concentration and pH over time was confirmed when the storage conditions were changed. The samples used in this experiment are as follows, and the results are shown in Figure 11. Each sample was filled into a 500ml colorless, transparent, non-light-shielding PET bottle.
Fig. 11A is a graph showing the results of Experimental Example 6, where the vertical axis indicates the effective chlorine concentration and the horizontal axis indicates the number of days of storage. Fig. 11B is a graph showing the results of Experimental Example 6, where the vertical axis indicates the pH and the horizontal axis indicates the number of days of storage.

Sample 14: "1 powder under fluorescent light" was prepared by mixing 180 mg of calcium hypochlorite and 2 g of potassium dihydrogen phosphate, dissolving them in 500 ml of distilled water, and storing them at room temperature (22°C) under fluorescent light (500 lx, 12 hours per day).
Sample 15: "Under 2 powder fluorescent lamp" was prepared by dissolving 180 mg of calcium hypochlorite in 500 ml of distilled water, and then dissolving 2 g of potassium dihydrogen phosphate in the solution. The solution was then stored at room temperature (22°C) under fluorescent lamps (500 lx, 12 hours per day).
Sample 16: "2 Powder Light Blocking" was prepared by dissolving 180 mg of calcium hypochlorite in 500 ml of distilled water, and then dissolving 2 g of potassium dihydrogen phosphate in the solution. The solution was then stored at room temperature (22°C) in a light-blocking environment.

From these results, it was confirmed that even when stored under the same conditions, hypochlorite and pH adjuster are far more stable when dissolved simultaneously, for example, when combined in powder or other solid form and then dissolved in water. The results were the same as for the "two powders" above, even when calcium hypochlorite was dissolved after dissolving the phosphate.

The above results and experimental conditions are summarized as follows.
(Performance of the composition for producing hypochlorous acid water and its confirmation conditions 2)
Powdered hypochlorite (calcium hypochlorite) and powdered pH adjuster (potassium dihydrogen phosphate) are dissolved in 500 mL of distilled water (DW) at the same time, and the same amount of 500 mL is filled into a colorless, transparent, non-light-shielding PET bottle. Even if the bottle is exposed to a 500 lux fluorescent lamp for 12 hours per day at an ambient temperature of 22°C for 14 days, the decrease in effective chlorine concentration (in the case of an increase, the decrease is considered to be zero) is less than 2% (preferably less than 1%), and the change in pH (in most cases the decrease) is less than 4% (preferably less than 3%, more preferably less than 2%).

In addition, in this experimental example, the changes in residual chlorine concentration and pH over time due to differences in storage conditions were confirmed for Samples 11 (above "Powder 1") and 12 (above "Powder 2") The storage conditions and changes in residual chlorine concentration and pH over time for each sample are shown in Table 7 below.

In this experimental example, the difference in the amount of precipitate due to the difference in the manufacturing method of hypochlorous acid water, that is, the difference in the timing of dissolving the hypochlorite and the pH adjuster, was confirmed. The precipitate was confirmed after storing for one week in a normal indoor environment. Figure 12 (A) shows the precipitate when calcium hypochlorite and potassium dihydrogen phosphate are dissolved in water at the same time, Figure 12 (B) shows the precipitate when calcium hypochlorite is added and potassium dihydrogen phosphate is added and dissolved before it is completely dissolved (mixed for one minute), Figure 12 (C) shows the precipitate when potassium dihydrogen phosphate is added and calcium hypochlorite is added and dissolved before it is completely dissolved (mixed for one minute), and Figure 12 (D) shows the precipitate when calcium hypochlorite is added and potassium dihydrogen phosphate is added and dissolved after it is completely dissolved.

The results of this experiment show that compared to adding calcium hypochlorite and potassium dihydrogen phosphate at the same time, adding each component in turn and dissolving them resulted in a greater amount of precipitate. This is thought to be because more phosphate ions in the generated solution react with calcium, resulting in more precipitation. Furthermore, since adding calcium hypochlorite and potassium dihydrogen phosphate at the same time inhibits the progress of the equilibrium reaction that occurs over time immediately after generation, this is thought to be one of the reasons why the solution remains stable for a long time after generation.

[Experimental Example 7: Powder Dissolution Test]
In this experimental example, the solubility in water of hypochlorite and pH adjuster, both of which are powders, due to the difference in particle size was confirmed. Calcium hypochlorite was used as hypochlorite, and potassium dihydrogen phosphate was used as pH adjuster. The amount of water used as the solvent was 500 ml, and the time required to dissolve 200 mg of calcium hypochlorite or 2 g of potassium dihydrogen phosphate was measured. The particle size and dissolution time of calcium hypochlorite and potassium dihydrogen phosphate are shown in Table 8 below.

From the above results, it was confirmed that calcium hypochlorite and potassium dihydrogen phosphate can be dissolved at any particle size, but it is desirable for the particle size to be at least 0.1 mm or less.

[Experimental Example 8: Storage Test]
In this experimental example, hypochlorite and pH adjuster, both of which are powders, were stored in a single container, and the characteristics of the hypochlorous acid water produced after storing them were confirmed. 180 mg of calcium hypochlorite was used as the hypochlorite, and 2 g of potassium dihydrogen phosphate was used as the pH adjuster.

A composition for producing hypochlorous acid water consisting of the above calcium hypochlorite powder and the above potassium dihydrogen phosphate powder (when dissolved in 500 ml, the calculated effective chlorine concentration is 220 ppm, pH 6) was placed together in a single microtube and stored for 7 and 30 days in a normal room environment (room temperature of about 22°C, exposed to fluorescent light with an average of 300-400 lux for 12 hours per day). During storage, calcium hypochlorite was layered on top of the potassium dihydrogen phosphate. As a result, there was no change before and after storage.

The composition for producing hypochlorous acid water after storage was dissolved in 500 ml of distilled water in a colorless, transparent, non-light-shielding PET bottle, mixed by inversion for about 1 minute, and then left for 5 minutes, and the effective chlorine concentration and pH were measured. As a result, the effective chlorine concentration was 224 ppm (free chlorine concentration: 222 ppm) and pH 6.05 after 7 days, and the effective chlorine concentration was 218 ppm (free chlorine concentration: 216 ppm) and pH 6.01 after 30 days, confirming that the initial characteristics could be maintained.

The above results and experimental conditions are summarized as follows.
(Performance of the composition for producing hypochlorous acid water and its confirmation conditions 3)
A composition for producing hypochlorous acid water consisting of the calcium hypochlorite powder and the potassium dihydrogen phosphate powder (when dissolved in 500 ml, the calculated effective chlorine concentration is 220 ppm and the pH is 6) was placed together in a single microtube and stored for 30 days in a normal indoor environment (room temperature of about 22°C, exposed to fluorescent lights with an average of 300 to 400 lux for 12 hours per day). Then, the powdered hypochlorite (calcium hypochlorite) and the powdered pH adjuster (potassium dihydrogen phosphate) are dissolved in 500 mL of distilled water (DW) at the same time, and the same amount of 500 mL is filled into a colorless, transparent, non-light-shielding PET bottle. Even if the bottle is exposed to an average of 300 to 400 lux of fluorescent light for 12 hours per day at an ambient temperature of 20±2°C for 30 days, the decrease in available chlorine concentration (in the case of an increase, the decrease is considered to be zero) is less than 3%, and the change in pH (in most cases the decrease) is less than 1%.

The composition for producing hypochlorous acid water in this embodiment may satisfy at least one of the above (Performance of composition for producing hypochlorous acid water and its confirmation conditions 1 to 3), or it may satisfy any combination of them, and it is more preferable that it satisfies all of them.

[Experimental Example 9: Stain adhesion test]
In this experimental example, hypochlorous acid water made from hypochlorous acid water producing composition composed of hypochlorite and pH adjuster in powder form is applied to a blackboard, and the presence and degree of stains (white deposits) are confirmed over time by changing the amount of phosphate added.In this experiment, the following samples are prepared by changing the amount of potassium dihydrogen phosphate added to a standard sample in which 200mg of calcium hypochlorite is dissolved in 500ml of distilled water.

Sample 17: 0g/500ml of potassium dihydrogen phosphate added to the standard sample. Sample 18: 1g/500ml of potassium dihydrogen phosphate added to the standard sample. Sample 19: 2g/500ml of potassium dihydrogen phosphate added to the standard sample. Sample 20: 3g/500ml of potassium dihydrogen phosphate added to the standard sample. Sample 21: 4g/500ml of potassium dihydrogen phosphate added to the standard sample. Sample 22: 5g/500ml of potassium dihydrogen phosphate added to the standard sample.

The presence and extent of spots (white deposits) were visually checked immediately after production, 6 hours later, and 1 week later. The results are shown in Figure 13.

This experiment confirmed that when the amount of potassium dihydrogen phosphate added to a standard sample of 200 mg of calcium hypochlorite dissolved in 500 ml of distilled water was 2 g/500 ml or less, no stains (white deposits) were formed. In addition, when 1 g/500 ml of potassium dihydrogen phosphate was added to the standard sample, a white precipitate was confirmed in the generated hypochlorous acid water, and after one week, slight stains (white deposits) were formed. In this experiment, each sample was left to dry after application, but since it is often wiped off in normal use, such stains (white deposits) rarely occur.

[Experimental Example 10: Corrosion Test]
In this experimental example, the corrosiveness of hypochlorous water made from a composition for producing hypochlorous acid water consisting of calcium hypochlorite and potassium dihydrogen phosphate was confirmed. In this experiment, a structure made of carbon steel (dental cutting bar, product name ELA steel bar CA 6. Matsukaze) was immersed in the following sample (liquid temperature 22±2°C) for 15 minutes, washed with distilled water (22±2°C), and dried at 22±2°C for 45 minutes. A series of steps (immersion, washing, drying) were repeated six times. The results are shown in FIG. 14. Below, the percentage is written at the end of the description of each sample. This value refers to the area percentage of the main surface of the structure that is occupied by rust in each sample when the area percentage of the main surface of the unused structure that is occupied by rust is set to 0 area percentage. The method of determining the area percentage occupied by rust is arbitrary, and may be visual estimation (this test example), or the area percentage occupied by rust may be determined by dividing the rusted area from the other areas by image processing.

Sample 23: Distilled water (15% by area)
Sample 24: 80% ethanol (Hayashi Pure Chemical Industries, Ltd.) (20% by area)
Sample 25: Sodium hypochlorite aqueous solution (1000 ppm) (product name: PYURAX (registered trademark), manufactured by OYALAX Co., Ltd.) (80% by area)
Sample 26: Sodium hypochlorite aqueous solution (250 ppm) (product name: PYURAX (registered trademark), manufactured by OYALAX Co., Ltd.) (70% by area)
Sample 27: Aqueous solution (250 ppm) (75 area%) in which only calcium hypochlorite was dissolved in 500 mL of distilled water
Sample 28: Hypochlorous acid water (50 ppm, pH 3.0) produced by electrolysis (prepared in the same manner as Sample 1) (70% by area)
Sample 29: Hypochlorous acid water (120 ppm, pH 6.5) produced by mixing carbon dioxide with an aqueous solution of sodium hypochlorite (prepared in the same manner as Sample 3) (55% by area)
Sample 30: Hypochlorous acid water (240 ppm, pH 6.7) produced by mixing sodium hypochlorite aqueous solution with hydrochloric acid (Sample 2) (70% by area)
Sample 31: Hypochlorous acid water (250 ppm) consisting of potassium dihydrogen phosphate (1000 mg/500 ml) and calcium hypochlorite. Specifically, 180 mg of calcium hypochlorite and the above potassium dihydrogen phosphate were dissolved in 500 mL of distilled water (DW). Each component was dissolved simultaneously. (5 area %)
Sample 32: Hypochlorous acid water (250 ppm) consisting of potassium dihydrogen phosphate (2000 mg/500 ml) and calcium hypochlorite. Specifically, 180 mg of calcium hypochlorite and the above potassium dihydrogen phosphate were dissolved in 500 mL of distilled water (DW). Each component was dissolved simultaneously. (4 area%)
Sample 33: Hypochlorous acid water (250 ppm) consisting of potassium dihydrogen phosphate (3000 mg/500 ml) and calcium hypochlorite. Specifically, 180 mg of calcium hypochlorite and the above potassium dihydrogen phosphate were dissolved in 500 mL of distilled water (DW). Each component was dissolved simultaneously. (3 area %)
Sample 34: Hypochlorous acid water (250 ppm) consisting of potassium dihydrogen phosphate (4000 mg/500 ml) and calcium hypochlorite. Specifically, 180 mg of calcium hypochlorite and the above potassium dihydrogen phosphate were dissolved in 500 mL of distilled water (DW). Each component was dissolved simultaneously. (3 area %)
Sample 35: Hypochlorous acid water (250 ppm) consisting of potassium dihydrogen phosphate (5000 mg/500 ml) and calcium hypochlorite. Specifically, 180 mg of calcium hypochlorite and the above potassium dihydrogen phosphate were dissolved in 500 mL of distilled water (DW). Each component was dissolved simultaneously. (2% by area)
Sample 36: Hypochlorous acid water (250 ppm) consisting of potassium dihydrogen phosphate (2000 mg/500 ml) and sodium hypochlorite. Specifically, an aqueous solution of sodium hypochlorite (6%) (product name: PYURAX (registered trademark), manufactured by OYALAX Co., Ltd.) was adjusted to an effective chlorine concentration of 250 ppm, and the potassium dihydrogen phosphate was dissolved in this aqueous solution. (5 area%)
Sample 37: Sodium dichloroisocyanurate aqueous solution (200 ppm) (85 area%)
Sample 38: Sodium dichloroisocyanurate aqueous solution (500 ppm) (90 area%)

From the results of this experiment, hypochlorous acid water produced from calcium hypochlorite and potassium dihydrogen phosphate, both of which are powders, caused less rust (the ratio of the area of rust to the area of the immersed part of the carbon steel was 10 area % or less, or more specifically 5 area % or less, 4 area % or less, 3 area % or less, and 2 area % or less), and caused less rust than sample 24, which used 80% ethanol. In particular, hypochlorous acid water using calcium hypochlorite caused almost no rust on carbon steel, unlike conventional hypochlorous acid water and water using dichloroisocyanuric acid, which is powder.

[Experimental Example 11: Bactericidal Test (ASTM E2315-031 Time-Kill Test)]
In this experimental example, the disinfecting effect of a composition for producing hypochlorous acid water, which is composed of hypochlorous acid and potassium dihydrogen phosphate as a powder pH adjuster, was confirmed in accordance with the ASTM E2315-031 Time-Kill test.
Sample 39: Sodium hypochlorite aqueous solution (250 ppm) (sample 26 is used)
Sample 40: Sodium hypochlorite aqueous solution (1000 ppm) (sample 25 is used)
Sample 41: 80% ethanol (based on Sample 24)
Sample 42: Hypochlorous acid water (57 ppm, pH 3.0) produced by electrolysis (prepared in the same manner as Sample 1)
Sample 43: Hypochlorous acid water (120 ppm, pH 6.5) produced by mixing carbon dioxide with a sodium hypochlorite aqueous solution (prepared in the same manner as Sample 3)
Sample 44: Hypochlorous acid water (240 ppm, pH 6.7) produced by mixing sodium hypochlorite aqueous solution with hydrochloric acid (prepared in the same manner as Sample 2)
Sample 45: Hypochlorous acid water (250 ppm, pH 6.2) produced by mixing carbon dioxide with an aqueous calcium hypochlorite solution (prepared by applying the same method as sample 3 to sample 27)
Sample 46: Hypochlorous acid water (250 ppm, pH 5.7) produced by dissolving calcium hypochlorite and potassium dihydrogen phosphate in water (prepared in the same manner as Samples 31 to 35, but adjusting the amount of potassium dihydrogen phosphate added to adjust the pH to 5.7)
Sample 47: Hypochlorous acid water (250 ppm, pH 5.8) produced by dissolving potassium dihydrogen phosphate in a sodium hypochlorite aqueous solution (prepared in the same manner as Sample 36, but the amount of potassium dihydrogen phosphate added was adjusted to pH 5.8)
The results are shown in Table 9 below.

Figure 15 shows the presence or absence of colony formation in disinfectant solutions consisting of hypochlorous acid water (250 ppm, pH 5.7) produced by dissolving the above calcium hypochlorite and potassium dihydrogen phosphate in water, and hypochlorous acid water (250 ppm, pH 5.8) produced by dissolving potassium dihydrogen phosphate in an aqueous solution of sodium hypochlorite, after immersion for 10 seconds, 30 seconds, and 60 seconds with the addition of 5% rabbit serum (Figure 15A shows without serum, and Figure 15B shows with serum).

The hypochlorous acid water produced by dissolving a hypochlorous acid water producing composition consisting of calcium hypochlorite and potassium dihydrogen phosphate in water is all food additives, and the experimental results confirmed that complete sterilization can be achieved in as little as 10 seconds. Therefore, it was found that the hypochlorous acid water produced by the hypochlorous acid water producing composition according to one embodiment of the present invention is comparable to hypochlorous acid water that has been provided in the past.

The composition for producing hypochlorous acid water according to one embodiment of the present invention can be used to easily and quickly produce hypochlorous acid water. In addition, the composition can be stored for a long period of time and then used to produce hypochlorous acid water when needed.

10: Hypochlorite, 11: pH adjuster, 20: Composition for producing hypochlorous acid water, 30: Water

Claims (13)

A composition for producing hypochlorous acid water that is solid,
The composition comprises a solid hypochlorite or a hydrate thereof and a solid pH adjuster,
The hypochlorite or its hydrate is calcium hypochlorite or sodium hypochlorite pentahydrate,
A composition for producing hypochlorous acid water, wherein the pH adjuster is potassium dihydrogen phosphate . The composition for producing hypochlorous acid water according to claim 1 , wherein the hypochlorite or its hydrate is calcium hypochlorite. The calcium hypochlorite has an effective chlorine concentration of 50% or more, or a dry effective chlorine concentration of more than 10%;
The composition for producing hypochlorous acid water according to claim 2 , wherein the purity of the potassium dihydrogen phosphate is 95% or more. The composition for producing hypochlorous acid water according to claim 2 or 3 , wherein the value of (weight of potassium dihydrogen phosphate)/(weight of calcium hypochlorite) is 1.5 or more and 100 or less. The calcium hypochlorite is a powder, and each particle constituting the powder has a particle size of 3.0 mm or less.
The composition for producing hypochlorous acid water according to any one of claims 2 to 4 , wherein the potassium dihydrogen phosphate is a powder, and each particle constituting the powder has a particle size of 3.0 mm or less. The composition for producing hypochlorous acid water according to any one of claims 1 to 5 , wherein the composition for producing hypochlorous acid water exhibits a rust-preventing function when in contact with water. The composition for producing hypochlorous acid water according to claim 6, wherein even when a series of steps of immersing carbon steel in a mixed solution (liquid temperature 22±2°C) of the composition for producing hypochlorous acid water and water for 15 minutes, rinsing the carbon steel with distilled water (22±2°C), and drying the carbon steel at 22±2°C for 45 minutes is repeated six times, the ratio of the area of rust to the area of the part of the carbon steel immersed in the mixed solution is 10 area% or less, thereby exhibiting a rust-preventing function. A hypochlorous acid water comprising the composition for producing hypochlorous acid water according to any one of claims 1 to 7 and water. The hypochlorite or hydrate thereof is calcium hypochlorite,
The pH adjuster is potassium dihydrogen phosphate;
The calcium hypochlorite has an effective chlorine concentration of 50% or more, or a dry effective chlorine concentration of more than 10%;
The purity of the potassium dihydrogen phosphate is 95% or more,
The amount of calcium hypochlorite added to the water is 10 mg/L or more and not more than a saturated concentration,
The amount of potassium dihydrogen phosphate added to the water is 50 mg/L or more and not exceeding a saturation concentration,
The hypochlorous acid water according to claim 8 , wherein the value of (amount of potassium dihydrogen phosphate added)/(amount of calcium hypochlorite added) is 1.5 or more and 100 or less. The hypochlorous acid water according to claim 8 or 9 , wherein the hypochlorous acid water has an anti-rust function. The hypochlorous acid water according to claim 10, wherein even when a series of steps of immersing carbon steel in the hypochlorous acid water (liquid temperature 22±2° C.) for 15 minutes, rinsing the carbon steel with distilled water (22±2° C.), and drying the carbon steel at 22±2° C. for 45 minutes is repeated six times, the ratio of an area of rust to an area of a portion of the carbon steel immersed in the hypochlorous acid water is 10 area % or less , thereby providing a rust-preventing function. A method for producing hypochlorous acid water, comprising contacting the composition for producing hypochlorous acid water according to any one of claims 1 to 7 with water. The hypochlorite or its hydrate and the pH adjuster are dissolved in water before the other is dissolved in water, or both are dissolved in water at the same time. The method for producing hypochlorous acid water according to claim 12 .