Calcium scale dissolving agent and method for cleaning dialysis equipment using the same

Abstract

Chlorine-based cleaning agents and calcium scale dissolving agents are used to clean dialysis equipment, but they may be mixed due to human error, etc. In this case, there is a risk of chlorine gas generation. [Solution] A calcium scale dissolving agent comprising water, at least one selected from sulfamic acid or a salt thereof, at least one selected from an organic acid or a salt thereof, and a pH adjuster, wherein the at least one selected from sulfamic acid or a salt thereof is present in an amount of 2.0% to 20.0% by mass, the at least one selected from an organic acid or a salt thereof is present in an amount of 5.0% to 40.0% by mass, and the pH is 4.5 to 6.5.

Description

Technical Field

[0001] The present invention is a calcium scale dissolving agent, and more particularly relates to a calcium scale dissolving agent for dialysis equipment.

[0002] Dialysis equipment refers to an artificial dialysis device used for dialysis treatment and its peripheral equipment (such as a dialysis fluid delivery tube and a delivery pump). Such dialysis equipment functions by integrating a blood control system that quantitatively and qualitatively adjusts the blood led outside the body and a system that controls the dialysis fluid when it comes into contact with the blood through a dialyzer (hollow fiber). At this time, metal ions (including calcium carbonate) in the delivered dialysis fluid form scale (including calcium scale) and precipitate, adhering to the inside of the tube. A calcium scale dissolving agent is used to dissolve and remove this adhered scale. In addition, the cleaning of dialysis equipment generally uses a chlorine-based cleaning agent in combination to remove bacteria and endotoxins and to remove organic substances such as waste products discharged by dialysis treatment and biofilms derived from bacteria. These cleaning agents are separately introduced into a cleaning agent storage tank attached to the dialysis equipment, diluted about 50 to 200 times, and used to clean the inside of the delivery tube through which the dialysis fluid flows.

[0003] Here, as a calcium scale dissolving agent, for example, the calcium scale dissolving agent of Patent Document 1 is known. The calcium scale dissolving agent of Patent Document 1 has a composition in which a carboxylic acid compound and a sulfonic acid compound are blended, and the pH of the blended compound is 3.0 or less.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the addition of chlorine-based cleaning agents and calcium scale dissolving agents to storage tanks is done manually, and occasionally, human error can occur, resulting in the wrong cleaning agent being added. In this case, if the chlorine-based cleaning agent and the calcium scale dissolving agent described in Patent Document 1 are mixed, chlorine gas will be generated. Chlorine gas can cause poisoning symptoms if inhaled, making this mistake extremely dangerous. Furthermore, there is a risk of chlorine gas generation due to the leakage and mixing of cleaning solutions caused by the tipping or damage of storage tanks during disasters such as earthquakes.

[0006] This invention has been made in view of the problems of the prior inventions, and provides a calcium scale dissolving agent that generates very little chlorine gas even when mixed with a chlorine-based cleaning agent. [Means for solving the problem]

[0007] To achieve the above objective, the present invention comprises at least the following configuration or performs the following procedure.

[0008] A calcium scale dissolving agent according to one aspect of the present invention comprises water, at least one selected from sulfamic acid or a salt thereof, at least one selected from an organic acid or a salt thereof, and a pH adjusting agent, wherein the at least one selected from sulfamic acid or a salt thereof is present in an amount of 2.0% to 20.0% by mass, the at least one selected from an organic acid or a salt thereof is present in an amount of 5.0% to 40.0% by mass, and the pH is 4.5 to 6.5. This configuration makes it possible to provide a calcium scale dissolving agent that generates extremely little chlorine gas even when mixed with chlorine-based cleaning agents.

[0009] Preferably, the organic acid is characterized by being at least one selected from succinic acid, maleic acid, fumaric acid, phthalic acid, butyric acid, acetic acid, propionic acid, glutaric acid, lactic acid, tartaric acid, malonic acid, salicylic acid, malic acid, citric acid, or salts thereof. This configuration allows for improved cleaning power.

[0010] Furthermore, preferably, the pH adjusting agent is characterized by being at least one selected from sodium hydroxide, potassium hydroxide, ammonia, and an inorganic alkali. This configuration can improve the solubility of organic acids.

[0011] Furthermore, preferably, the product is characterized by containing a rust inhibitor and / or a preservative. This configuration makes it possible to suppress the occurrence of rust and prevent corrosion.

[0012] A method for cleaning dialysis equipment according to one aspect of the present invention is a method for cleaning dialysis equipment using a calcium scale dissolving agent comprising water, at least one selected from sulfamic acid or a salt thereof, at least one selected from an organic acid or a salt thereof, and a pH adjusting agent, wherein the at least one selected from sulfamic acid or a salt thereof is in an amount of 2.0% to 20.0% by mass, the at least one selected from an organic acid or a salt thereof is in an amount of 5.0% to 40.0% by mass, and the pH is 4.5 to 6.5, characterized in that the calcium scale dissolving agent is diluted by adding water so that the concentration of at least one selected from an organic acid or a salt thereof is 0.15% to 2.00% by mass before use. This configuration makes it possible to extremely reduce the amount of chlorine gas generated even if chlorine-based cleaning agents are accidentally mixed in. [Effects of the Invention]

[0013] As described above, the calcium scale dissolving agent of the present invention can significantly reduce the amount of chlorine gas generated even when mixed with chlorine-based cleaning agents due to human error or the like. [Modes for carrying out the invention]

[0014] The following describes in detail one embodiment of the present invention. It should be noted that the embodiments described below are merely examples of specific actions for carrying out the present invention and are not intended to limit the scope of the invention.

[0015] The calcium scale dissolving agent of the present invention is for cleaning dialysis equipment and contains water, sulfamic acid, an organic acid, and a pH adjuster, with a pH in the range of 4.5 to 6.5. Rust inhibitors, preservatives, and other auxiliary agents may be added as appropriate. When a rust inhibitor is added, the occurrence of rust can be suppressed. When a preservative is added, spoilage can be prevented.

[0016] Deionized water, distilled water, purified water, etc., can be used as appropriate.

[0017] Not only sulfamic acid, but at least one selected from sulfamic acid or its salts can be used. In addition to sulfamic acid, methylsulfamic acid, benzylsulfamic acid, sulfamides and their neutralized salts (e.g., sodium salts, potassium salts), as well as combinations thereof, can also be used. Derivatives of sulfamic acid can also be used.

[0018] The total mass of the aqueous solution containing sulfamic acid is in the range of 2.0% to 20.0% by mass, preferably in the range of 4.0% to 15.0% by mass. When a calcium scale dissolving agent and a chlorine-based cleaning agent are mixed, sulfamic acid reacts with hypochlorous acid contained in the chlorine-based cleaning agent to produce bound chlorine. Chlorine bound to sulfamic acid is stable in aqueous solution and does not replace chlorine gas, thus suppressing the generation of chlorine gas. Increasing the concentration of sulfamic acid above 20.0% by mass reduces the total water content of the aqueous solution, which reduces the content of organic acids; therefore, a sulfamic acid concentration of 20.0% by mass or less is desirable.

[0019] The organic acid may be at least one selected from organic acids or their salts, specifically including succinic acid, maleic acid, fumaric acid, phthalic acid, butyric acid, acetic acid, propionic acid, glutaric acid, lactic acid, tartaric acid, malonic acid, salicylic acid, malic acid, citric acid, and their neutralized salts (e.g., sodium salts, potassium salts), as well as combinations thereof. The organic acid dissolves calcium scale such as calcium carbonate. Since the pH of the calcium scale dissolving agent of the present invention is 4.5 to 6.5, maleic acid, malonic acid, acetic acid, malic acid, citric acid, and combinations thereof are more preferred because they have high calcium scale dissolving performance in this pH range and are readily available.

[0020] For organic acids to exhibit calcium scale dissolving performance, the pH must be 6.5 or lower. If the pH is higher than 6.5, they cannot effectively dissolve calcium scale during the cleaning process of dialysis equipment. Furthermore, if the pH of the calcium scale dissolving agent drops below 4.5, the amount of chlorine gas generated increases when mixed with chlorine-based cleaning agents. This is because chlorine-based cleaning agents are alkaline, and the hypochlorite ions they contain become hypochlorous acid when the pH drops below 8.5, and chlorine gas when the pH drops below 4.5. Therefore, the pH of the calcium scale dissolving agent should be 4.5 or higher, preferably 5.0 or higher. For this reason, the pH of the calcium scale dissolving agent of the present invention is in the range of 4.5 to 6.5, and preferably in the range of 5.0 to 6.0.

[0021] The organic acid ranges from 5.0% to 40.0% by mass of the total mass of the calcium scale dissolving agent of the present invention, preferably from 15.0% to 35.0% by mass. It is preferable that the cleaning agent has a high concentration when it is put into the storage tank attached to the dialysis equipment. In the cleaning of the liquid delivery tube of the dialysis equipment, etc., it is common to dilute the cleaning agent 50 to 200 times before use. By increasing the concentration of the cleaning agent, the delivery cost can be reduced and the labor of cleaning and inputting into the storage tank can be reduced. Also, when the concentration of the organic acid is 40.0% by mass or more, it exceeds the solubility and cannot be used as an aqueous solution.

[0022] It is desirable that the mixing ratio of the organic acid and sulfamic acid in the calcium scale dissolving agent of the present invention is in a mass ratio of organic acid:sulfamic acid = 20:1 to 1:1. This is because sulfamic acid has very low calcium scale dissolving performance in the range of pH = 4.5 to 6.5. As the amount of sulfamic acid increases, the amount of water decreases, and thus the amount of the organic acid decreases.

[0023] The pH adjuster is intended to finally adjust the pH of the calcium scale dissolving agent to the range of 4.5 to 6.5, and examples include sodium hydroxide, potassium hydroxide, ammonia, alkanolamine, other inorganic alkalis, and combinations thereof. Potassium hydroxide is preferable because the solubility of the organic acid is the highest.

[0024] When sulfamic acid is added, when the calcium scale dissolving agent of the present invention is mixed with a chlorine-based cleaning agent, the rise in the liquid temperature of the mixed solution is suppressed. The rise in the liquid temperature is not preferable because, in addition to promoting the generation of chlorine gas, there is a possibility that the operator who inputs the cleaning liquid may be burned. Also, in the case of a conventional calcium scale dissolving agent, it was confirmed that violent foaming occurred in the tank due to misinput, but the addition of sulfamic acid suppresses foaming and can reduce the risk of scattering of the chlorine-based cleaning agent.

[0025] While chelating agents such as ethylenediaminetetraacetic acid (EDTA) and hydroxyethylethylenediaminetriacetic acid (HEDTA) are also used as calcium scale dissolving agents, the inclusion of these chelating agents is inappropriate because it promotes the generation of chlorine gas when mixed with chlorine-based cleaning agents.

[0026] Besides sulfamic acid, other compounds that generate bound chlorine include thiourea, saccharin, hydantoin, and cyanuric acid, but none of them were found to suppress chlorine gas generation when mixed with chlorine-based cleaning agents.

[0027] Commercially available chlorine-based cleaning agents include 12% sodium hypochlorite solution (12% or more available chlorine), ECO-200 (6% or more available chlorine) and HIDEC-TT (3% or more available chlorine) manufactured by Amtec Co., Ltd., and these are cleaning agents for dialysis equipment that contain sodium hypochlorite.

[0028] The available chlorine contained in chlorine-based cleaning agents refers to hypochlorous acid and hypochlorite ions. Available chlorine has a strong oxidizing power that destroys the cell membranes of microorganisms and viruses, and also denatures proteins, thereby providing sterilization and cleaning effects.

[0029] The calcium scale dissolving agent of the present invention is used diluted when cleaning dialysis equipment. This is because the calcium dissolving performance is sufficient when the concentration of the organic acid is between 0.15% by mass and 2.00% by mass. A range of 0.50% by mass and 1.00% by mass is particularly preferred. If the concentration of the organic acid is lower than 0.15% by mass, the calcium scale dissolving performance is not satisfactory. Furthermore, if the concentration of the organic acid is higher than 2.00% by mass, the dilution ratio becomes low, the amount of cleaning agent used increases, and the cost of the cleaning agent increases, which is undesirable. Depending on the concentration of the organic acid in the calcium scale dissolving agent of the present invention, it is preferable to dilute it 15 to 200 times when cleaning dialysis equipment. [Examples]

[0030] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0031] <Preparation of calcium scale dissolving agent> The examples and comparative examples were prepared using the proportions shown in the table. Concentration adjustments were made by adding deionized water.

[0032] <Changes in liquid temperature and visual appearance in case of accidental contamination> In a 50 mL polyethylene container, 4.0 mL of calcium scale dissolving agent and 16.0 mL of chlorine-based cleaning agent (mixing ratio 1:4), or 16.0 mL of calcium scale dissolving agent and 4.0 mL of chlorine-based cleaning agent (mixing ratio 4:1), were mixed. The appearance of the mixture was checked, and the temperature of the mixture was measured after 5 minutes. The temperature was measured using a Horiba F-72T measuring device.

[0033] <Method for measuring chlorine gas concentration in case of incorrect application> In a 4.3L sealed container, 0.4mL of calcium scale dissolving agent and 1.6mL of chlorine-based cleaning agent (mixture ratio 1:4) or 1.6mL of calcium scale dissolving agent and 0.4mL of chlorine-based cleaning agent (mixture ratio 4:1) were added to a petri dish and mixed. After 2 minutes, the gas inside was collected using a sampling device (manufactured by Komei Rikagaku Kogyo Co., Ltd.) equipped with a detector tube (manufactured by Gastec Co., Ltd., measurement range 0.1~16ppm), and the chlorine gas concentration was measured.

[0034] One possible response to the generation of chlorine gas is to wear a gas mask. However, the maximum permissible permeation concentration (the highest concentration at which the concentration of chlorine gas in the air passing through the absorbent canister attached to the gas mask does not exceed the canister's limit) for gas masks suitable for chlorine gas is 1.0 ppm. Therefore, the permissible concentration when chlorine gas is generated is set at 1.0 ppm. A chlorine gas concentration of 0.1 ppm or less is preferable, as it has little impact on the human body even without wearing a gas mask.

[0035] <Test method for calcium scale dissolution performance> 50.0 mL of the calcium scale dissolving agent, diluted with deionized water, was mixed with 0.300 g of calcium carbonate, stirred at 25°C for 30 minutes, and then filtered. The amount of dissolved calcium carbonate was calculated and evaluated from the residue.

[0036] Table 1 shows the test results when citric acid was added as an organic acid and the amount of sulfamic acid was adjusted from 0.0% by mass to 18.0% by mass. The pH of each formulation was adjusted to 5.0 with potassium hydroxide. A 12% sodium hypochlorite solution was used as the chlorine-based cleaning agent. In Examples 1 to 5, when the amount of sulfamic acid was in the range of 2.0% by mass to 18.0% by mass, the amount of chlorine gas generated in the evaluation of incorrect addition was 1.0 ppm or less, and the liquid temperature rise was small and foaming was suppressed.

[0037] On the other hand, when 1.0% sulfamic acid was added in Comparative Example 1, a reduction in chlorine gas generation was observed, but the rise in liquid temperature and the appearance did not improve. Furthermore, in Comparative Example 2, the calcium scale dissolving agent adjusted with citric acid and a pH adjuster resulted in a chlorine gas generation rate of 2.0 ppm in the erroneous addition evaluation. When the ratio of calcium scale dissolving agent to 12% sodium hypochlorite was 1:4, the liquid temperature rose to 70.4°C, and severe foaming was observed, creating a dangerous situation with a high risk of burns to workers.

[0038] The foaming that occurs when a substance is accidentally mixed in is not necessarily due to chlorine gas; the generation of oxygen can also be a contributing factor. It is generally known that hypochlorous acid is decomposed by acid (2HClO → 2HCl + O2).

[0039] TIFF2026085632000001.tif39166

[0040] Table 2 shows the test results when malic acid was added as an organic acid. In Comparative Example 3, chlorine gas was generated at a rate of 4.0 ppm or higher in the incorrect addition evaluation, but by adding sulfamine at 18% by mass, 8% by mass, and 4% by mass as in Examples 6 to 8, the amount of chlorine gas generated was reduced to 1.0 ppm or less.

[0041] TIFF2026085632000002.tif41166

[0042] Table 3 shows the test results when maleic acid was added as an organic acid. In Comparative Example 4, chlorine gas was generated at a rate of 5.0 ppm or higher in the incorrect addition evaluation. However, by adding sulfamine at 12.0% by mass and 8.0% by mass, as in Examples 9 and 10, the amount of chlorine gas generated was reduced to 1.0 ppm or less. Furthermore, an effect of suppressing the rise in liquid temperature was also confirmed.

[0043] TIFF2026085632000003.tif39166

[0044] Table 4 shows the test results when malonic acid was added as an organic acid. In Comparative Example 5, chlorine gas was generated at a rate of 8.0 ppm or higher in the incorrect addition evaluation, but by adding sulfamine at 18.0% by mass and 8.0% by mass, as in Examples 11 and 12, the amount of chlorine gas generated was reduced to 1.0 ppm or less.

[0045] TIFF2026085632000004.tif39166

[0046] Table 5 shows the results when acetic acid, citric acid, and malic acid were added as organic acids. In Comparative Examples 6 and 7, sulfamic acid was not added, resulting in the generation of chlorine gas at a concentration of 4.0 ppm or higher when it was accidentally added. In Examples 13 and 14, sulfamic acid was added to each, and the amount of chlorine gas generated was 1.0 ppm or less. Furthermore, the rise in liquid temperature was also suppressed.

[0047] TIFF2026085632000005.tif46166

[0048] Table 6 shows the test results when citric acid was added as an organic acid and the pH of the calcium scale dissolving agent was adjusted to 7.0 to 3.0. In Comparative Example 8, the calcium scale dissolving agent adjusted to pH=4.0 generated 1.5 to 2.0 ppm of chlorine gas when accidentally added. In Comparative Example 9, the calcium scale dissolving agent adjusted to pH=3.0 generated 2.5 to 3.0 ppm of chlorine gas when accidentally added. In Examples 15 to 18, the calcium scale dissolving agents adjusted to pH=4.5 to 7.0 all generated 1.0 ppm or less of chlorine gas.

[0049] These test results suggest that when a calcium scale dissolving agent with a pH of 4.0 or lower is mixed with a sodium hypochlorite solution, the pH of the mixture locally decreases, causing free chlorine (hypochlorite ions) in the mixture to convert into chlorine gas. Although sulfamic acid can combine with free chlorine to form combined chlorine, it is presumed that the local decrease in pH causes chlorine gas to form before this reaction can occur.

[0050] TIFF2026085632000006.tif39166

[0051] Table 7 shows the test results for compounds that react with available chlorine to form bound chlorine.

[0052] Comparative Example 10 presents the test results of a calcium scale dissolving agent containing citric acid as an organic acid and saccharin, which forms bound chlorine. When the agent was mistakenly added, the amount of chlorine gas generated exceeded 8 ppm. This result exacerbated the generation of chlorine gas, and no effective effect was confirmed.

[0053] Comparative Example 11 presents the test results for a calcium scale dissolving agent containing citric acid as an organic acid and thiourea, which forms bound chlorine. The amount of chlorine gas generated when the agent was mistakenly added exceeded 16.0 ppm. This result exacerbated the generation of chlorine gas, and no effective effect was confirmed.

[0054] In Comparative Examples 10 and 11, we conducted tests using compounds other than sulfamic acid that can form bound chlorine, but in none of them was it possible to confirm an effect in reducing chlorine gas due to accidental addition. This is presumably because sulfamic acid can generate bound chlorine even in liquids where organic acids are present.

[0055] Comparative Example 12 presents the test results for a mixture containing citric acid, sulfamic acid, and ethylenediaminetetraacetic acid (EDTA) as organic acids. In a test involving the incorrect addition of a calcium scale dissolving agent: 12% sodium hypochlorite = 1:4, 8.0 ppm of chlorine gas was generated. An increase in liquid temperature was also observed. This is presumed to be because the rapid reaction of EDTA with hypochlorous acid generated heat, which increased the liquid temperature and promoted the generation of chlorine gas.

[0056] TIFF2026085632000007.tif49166

[0057] Table 8 shows the test results for a calcium scale dissolving agent containing citric acid as an organic acid, further containing sulfamic acid, and a chlorine-based cleaning agent manufactured by Amtec Co., Ltd.

[0058] Example 19 shows the results of an accidental application test using ECO-200, a chlorine-based cleaning agent manufactured by Amtec Co., Ltd. The results of the accidental application test showed that the amount of chlorine gas generated was less than 0.1 ppm, indicating that these cleaning agents generate very little chlorine gas when accidentally applied.

[0059] Example 20 shows the results of an accidental application test using HIDEC-TT, manufactured by Amtec Co., Ltd., as a chlorine-based cleaning agent. In the accidental application test, the amount of chlorine gas generated was 0.1 ppm or less, indicating that even with these cleaning agents, the generation of chlorine gas was very small when they were accidentally applied.

[0060] The generation of chlorine gas in the event of accidental application depends on the effective chlorine concentration of the chlorine-based cleaning agent. As the effective chlorine concentration decreased, the concentration of chlorine gas in the event of accidental application also decreased.

[0061] TIFF2026085632000008.tif63166

[0062] Table 9 shows the calcium scale dissolving performance of the calcium scale dissolving agent of Example 3 when diluted. The calcium scale dissolving agent of Example 3 was diluted with deionized water, with Example 21 being diluted 200 times, Example 22 being diluted 150 times, Example 23 being diluted 60 times, Example 24 being diluted 30 times, Example 25 being diluted 15 times, and Comparative Example 13 being diluted 300 times.

[0063] In Examples 21-25, the calcium scale dissolving performance as a cleaning agent for dialysis equipment was confirmed to be sufficient. However, in Comparative Example 13, the performance was not satisfactory. This is because increasing the dilution ratio lowered the concentration of citric acid, making it difficult to dissolve the calcium scale. An appropriate concentration of organic acid is considered to be between 0.15% by mass and 2.00% by mass.

[0064] TIFF2026085632000009.tif25166 [Industrial applicability]

[0065] The calcium scale dissolving agent according to the present invention is useful because it generates very little chlorine gas even when mixed with chlorine-based cleaning agents, thus posing a low risk even if mixed due to human error.

Claims

1. Water and, At least one selected from sulfamic acid or its salts, At least one selected from organic acids or their salts, It contains a pH adjuster, At least one selected from the sulfamic acid or its salts is present in an amount of 2.0% to 20.0% by mass. At least one selected from the aforementioned organic acids or their salts is present in an amount of 5.0% to 40.0% by mass. A calcium scale dissolving agent characterized by having a pH of 4.5 to 6.

5.

2. The calcium scale dissolving agent according to claim 1, characterized in that the organic acid is at least one selected from succinic acid, maleic acid, fumaric acid, phthalic acid, butyric acid, acetic acid, propionic acid, glutaric acid, lactic acid, tartaric acid, malonic acid, salicylic acid, malic acid, citric acid, or salts thereof.

3. The calcium scale dissolving agent according to claim 1 or 2, characterized in that the pH adjusting agent is at least one selected from sodium hydroxide, potassium hydroxide, ammonia, and an inorganic alkali.

4. A calcium scale dissolving agent according to claim 1 or 2, characterized by comprising a rust inhibitor and / or a preservative.

5. Water and, At least one selected from sulfamic acid or its salts, At least one selected from organic acids or their salts, It contains a pH adjuster, At least one selected from the sulfamic acid or its salts is present in an amount of 2.0% to 20.0% by mass. At least one selected from the aforementioned organic acids or their salts is present in an amount of 5.0% to 40.0% by mass. A method for cleaning dialysis equipment using a calcium scale dissolving agent with a pH of 4.5 to 6.5, A method for cleaning dialysis equipment, characterized by adding water to the calcium scale dissolving agent and diluting it so that the concentration of at least one selected from the organic acid or its salt is 0.15% by mass to 2.00% by mass.

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