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 being generated. [Solution] A calcium scale dissolving agent comprising water, at least one selected from sulfamic acid or a salt thereof, at least one selected from organic acids or a salt thereof, and a pH adjuster, wherein the at least one selected from the sulfamic acid or a salt thereof is present at 2.0% by mass to 20.0% by mass, the at least one selected from the organic acid or a salt thereof is present at 5.0% by mass to 40.0% by mass, and the pH is 4.5 to 6.5.

Description

[Technical field]

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

[0002] Dialysis equipment refers to an artificial dialysis device used in dialysis treatment and its peripheral equipment (dialysis fluid delivery tubes, delivery pumps, etc.). Such dialysis equipment functions as an integrated system consisting of a blood control system that adjusts the quantity and quality of blood led out of the body and a system that controls the dialysis fluid when it comes into contact with blood through a dialyzer (hollow fiber). At this time, metal ions (including calcium carbonate) in the dialysis fluid being delivered become 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 attached scale. In addition to calcium scale dissolving agents, chlorine-based cleaning agents are generally used in combination with dialysis equipment to remove bacteria and endotoxins, and to remove waste products discharged during dialysis treatment and organic matter such as biofilms derived from bacteria. These cleaning agents are separately charged into cleaning agent storage tanks 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 an example of a calcium scale dissolving agent, there is known the calcium scale dissolving agent described in Patent Document 1. The calcium scale dissolving agent in 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 compounds is 3.0 or less. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-216832 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the chlorine-based cleaning agent and calcium scale dissolving agent are added to the storage tanks by humans, and occasionally human error can result in the wrong cleaning agent being added (mis-added). In this case, when the chlorine-based cleaning agent and the calcium scale dissolving agent described in Patent Document 1 or the like are mixed, chlorine gas is generated. If a person inhales chlorine gas, it can cause poisoning, making the wrong addition extremely dangerous. In addition, there is a risk that chlorine gas will be generated if the storage tank falls over or breaks due to a disaster such as an earthquake, causing the cleaning solution to spill out and mix with the other cleaning solutions.

[0006] The present invention has been made in consideration of the problems associated with the conventional inventions, and provides a calcium scale dissolving agent which generates an extremely small amount of chlorine gas even when mixed with a chlorine-based cleaning agent. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention has at least the following configuration or executes the following procedures.

[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 organic acids or salts thereof, and a pH adjuster, wherein the at least one selected from the sulfamic acid or a salt thereof is 2.0% by mass to 20.0% by mass, the at least one selected from the organic acid or a salt thereof is 5.0% by mass to 40.0% by mass, and the pH is 4.5 to 6.5. With this configuration, it is possible to provide a calcium scale dissolving agent which generates an extremely small amount of chlorine gas even when mixed with a chlorine-based cleaning agent.

[0009] Also, preferably, 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 a salt thereof. With this configuration, the cleaning power can be further improved.

[0010] In addition, preferably, the pH adjuster is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonia, and inorganic alkali. With this configuration, the solubility of the organic acid can be improved.

[0011] Preferably, the composition further comprises a rust inhibitor and / or a preservative. With this configuration, rust generation can be suppressed and decay can be prevented.

[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 organic acids or a salt thereof, and a pH adjuster, wherein the at least one selected from the sulfamic acid or a salt thereof is 2.0% by mass to 20.0% by mass, the at least one selected from the organic acid or a salt thereof is 5.0% by mass to 40.0% by mass, and has a pH of 4.5 to 6.5, and is characterized in that the calcium scale dissolving agent is diluted with water so that the concentration of the at least one selected from the organic acid or a salt thereof is 0.15% by mass to 2.00% by mass. With this configuration, even if a chlorine-based cleaning agent is mistakenly mixed, the amount of chlorine gas generated can be extremely reduced. Effect of the Invention

[0013] As described above, the calcium scale dissolving agent of the present invention can extremely reduce the amount of chlorine gas generated even if it is mixed with a chlorine-based cleaning agent due to human error or the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of the present invention will be specifically described below. Note that the embodiment described below is merely a specific example for carrying out the present invention, and is not intended to limit the present invention.

[0015] The calcium scale dissolving agent of the present invention is used for cleaning dialysis equipment, and contains water, sulfamic acid, an organic acid, and a pH adjuster, and has a pH range of 4.5 to 6.5. In addition, rust inhibitors, preservatives, and other auxiliary agents may be added as appropriate. When a rust inhibitor is added, the generation of rust can be suppressed. Furthermore, when a preservative is added, decay can be prevented.

[0016] As the water, ion-exchanged water, distilled water, purified water, etc. can be used appropriately.

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

[0018] The total mass of the aqueous solution of sulfamic acid is in the range of 2.0% by mass to 20.0% by mass, preferably in the range of 4.0% by mass to 15.0% by mass. When the calcium scale dissolving agent and the chlorine-based cleaning agent are mixed, the sulfamic acid reacts with the hypochlorous acid contained in the chlorine-based cleaning agent to generate combined chlorine. The chlorine combined with the sulfamic acid is stable in the aqueous solution and is not replaced by chlorine gas, so the generation of chlorine gas can be suppressed. Note that if the concentration of sulfamic acid is increased above 20.0% by mass, the water content of the entire aqueous solution decreases, which causes a decrease in the content of organic acids, so the concentration of sulfamic acid is preferably 20.0% by mass or less.

[0019] The organic acid may be at least one selected from organic acids or their salts, and specific examples thereof include 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 neutral salts thereof (e.g., sodium salts, potassium salts), and combinations thereof. The organic acid dissolves calcium scale such as calcium carbonate. Since the calcium scale dissolving agent of the present invention has a pH of 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 that pH range and are easily available.

[0020] In order for an organic acid to exhibit calcium scale dissolving ability, the pH must be 6.5 or less. If the pH is higher than 6.5, the organic acid cannot effectively dissolve calcium scale during the cleaning process of dialysis equipment. In addition, if the pH of the calcium scale dissolving agent is lower than 4.5, the amount of chlorine gas generated increases when the agent is mixed with a chlorine-based cleaning agent. This is because the chlorine-based cleaning agent is alkaline, and the hypochlorite ions contained therein become hypochlorous acid when the pH is 8.5 or less, and become chlorine gas when the pH is lower than 4.5. Therefore, it is desirable that the pH of the calcium scale dissolving agent is 4.5 or more, and preferably 5.0 or more. 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 is in the range of 5.0% by mass to 40.0% by mass, preferably 15.0% by mass to 35.0% by mass, of the total mass of the calcium scale dissolving agent of the present invention. It is preferable that the cleaning agent is high-concentration when it is put into a storage tank attached to a dialysis machine. In cleaning the liquid supply tube of a dialysis machine, the cleaning agent is generally diluted 50 to 200 times before use. By increasing the concentration of the cleaning agent, it is possible to reduce the delivery cost and the labor of putting it into a storage tank for cleaning. In addition, if the concentration of the organic acid is 40.0% by mass or more, it cannot be used as an aqueous solution because it exceeds the solubility.

[0022] The blending ratio by mass of the organic acid to sulfamic acid in the calcium scale dissolving agent of the present invention is preferably organic acid:sulfamic acid = 20:1 to 1:1. This is because sulfamic acid has very low calcium scale dissolving performance in the pH range of 4.5 to 6.5, and therefore, when the blending amount of sulfamic acid increases, the water content decreases, and therefore the blending amount of organic acid decreases.

[0023] The pH adjuster is intended to adjust the final pH of the calcium scale dissolving agent to a range of 4.5 to 6.5, and examples of such pH adjusters include sodium hydroxide, potassium hydroxide, ammonia, alkanolamines, other inorganic alkalis, and combinations thereof. Potassium hydroxide is preferred because it provides the highest solubility of the organic acid.

[0024] The incorporation of sulfamic acid suppresses the rise in the temperature of the mixed solution when the calcium scale dissolving agent of the present invention is mixed with a chlorine-based cleaning agent. A rise in the temperature of the mixed solution is not desirable because it promotes the generation of chlorine gas and may cause burns to the operator who pours the cleaning solution. In addition, it has been confirmed that conventional calcium scale dissolving agents foam violently in the tank when poured incorrectly, but the incorporation of sulfamic acid suppresses foaming and reduces the risk of the chlorine-based cleaning agent scattering.

[0025] Chelating agents such as ethylenediaminetetraacetic acid (EDTA) and hydroxyethylethylenediaminetriacetic acid (HEDTA) are also used as calcium scale dissolving agents, but the incorporation of these chelating agents into chlorine-based cleaning agents is not appropriate because they promote the generation of chlorine gas when mixed with the agent.

[0026] In addition to sulfamic acid, compounds that generate combined chlorine include thiourea, saccharin, hydantoin, and cyanuric acid, but none of these have been shown to have any effect in suppressing the generation of chlorine gas 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. 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 even denatures proteins, resulting in sterilization and cleaning effects.

[0029] The calcium scale dissolving agent of the present invention is diluted before use when cleaning dialysis equipment. This is because the calcium dissolving performance is sufficient if the concentration of the organic acid is 0.15% by mass to 2.00% by mass. In particular, the range of 0.50% by mass to 1.00% by mass is preferable. If the concentration of the organic acid is lower than 0.15% by mass, the calcium scale dissolving performance is not satisfactory. In addition, if the concentration of the organic acid is higher than 2.00% by mass, the dilution ratio is low, and the amount of the cleaning agent used increases, which is not preferable, and therefore the cost of the cleaning agent increases. Note that, although it depends on the concentration of the organic acid of the calcium scale dissolving agent of the present invention, it is preferable to dilute it 15 times to 200 times before use 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> In the examples and comparative examples, the compositions were prepared in the amounts shown in the table. The concentrations were adjusted by adding ion-exchanged water.

[0032] <Changes in liquid temperature and appearance when mixed in> In a 50mL polyethylene container, 4.0mL of calcium scale dissolving agent adjusted to 25℃ and 16.0mL of chlorine-based cleaning agent (mixing ratio 1:4) or 16.0mL of calcium scale dissolving agent and 4.0mL of chlorine-based cleaning agent (mixing ratio 4:1) were mixed, and the appearance of the mixture was checked and the temperature of the mixture was measured after 5 minutes. The liquid temperature was measured using a Horiba Ltd. F-72T.

[0033] <Test method for measuring chlorine gas concentration when incorrectly added> 0.4 mL of calcium scale dissolving agent and 1.6 mL of chlorine-based cleaning agent (mixture ratio 1:4) or 1.6 mL of calcium scale dissolving agent and 0.4 mL of chlorine-based cleaning agent (mixture ratio 4:1) were placed in a petri dish in a 4.3 L sealed container and mixed, and after 2 minutes the internal gas was sampled using a sampler (manufactured by Komyo Rikagaku Kogyo Co., Ltd.) equipped with a detector tube (manufactured by Gastec Corporation, measurement range 0.1 to 16 ppm) to measure the chlorine gas concentration.

[0034] One way to deal with chlorine gas is to wear a gas mask, but since the maximum permeation concentration of a gas mask suitable for chlorine gas is 1.0 ppm (the maximum concentration of chlorine gas in the air that passes through the canister attached to the gas mask, which does not exceed the limit of the canister when chlorine gas-containing air is passed through the canister), 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 more preferable because it has less impact on the human body even without wearing a gas mask.

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

[0036] Table 1 shows the test results when citric acid was blended as an organic acid and the blending amount of sulfamic acid was adjusted from 0.0 mass% to 18.0. The pH of each blend 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 blending amount of sulfamic acid was in the range of 2.0 mass% to 18.0 mass%, the amount of chlorine gas generated in the evaluation of incorrect addition was 1.0 ppm or less, the liquid temperature rise was small, and foaming was suppressed.

[0037] On the other hand, when sulfamic acid was added at 1.0% in Comparative Example 1, the phenomenon of a reduction in the amount of chlorine gas generated was confirmed, but the rise in liquid temperature and the state of appearance were not improved. In addition, in the calcium scale dissolving agent adjusted with citric acid and a pH adjuster in Comparative Example 2, the amount of chlorine gas generated in the evaluation of incorrect addition was 2.0 ppm, and when the ratio of calcium scale dissolving agent to 12% sodium hypochlorite was 1:4, the liquid temperature rose to 70.4°C and vigorous foaming was confirmed, creating a high risk of burns to workers and a dangerous condition.

[0038] The foaming that occurs when chlorine gas is mixed in is not necessarily caused by chlorine gas, but may also be caused by the generation of oxygen. It is generally known that hypochlorous acid is decomposed by acid (2HClO→2HCl+O 2 ).

[0039] TIFF0007689403000001.tif39166

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

[0041] TIFF0007689403000002.tif41166

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

[0043] TIFF0007689403000003.tif39166

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

[0045] TIFF0007689403000004.tif39166

[0046] Table 5 shows the results when acetic acid, citric acid, and malic acid were used as organic acids. In Comparative Examples 6 and 7, sulfamine was not used, so chlorine gas was generated at 4.0 ppm or more when the acid was mistakenly added. In Examples 13 and 14, sulfamic acid was used, and the amount of chlorine gas generated was 1.0 ppm or less. The rise in liquid temperature was also suppressed.

[0047] TIFF0007689403000005.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. When the calcium scale dissolving agent of Comparative Example 8, adjusted to pH = 4.0, was mistakenly added, the amount of chlorine gas generated was 1.5 to 2.0 ppm. When the calcium scale dissolving agent of Comparative Example 9, adjusted to pH = 3.0, was mistakenly added, the amount of chlorine gas generated was 2.5 to 3.0 ppm. In Examples 15 to 18, when the calcium scale dissolving agents were adjusted to pH = 4.5 to 7.0, the amount of chlorine gas generated was 1.0 ppm or less.

[0049] This test result is believed to be due to the fact that when a calcium scale dissolving agent with a pH of 4.0 or less is mixed with a sodium hypochlorite solution, the pH of the mixed solution drops locally, causing the free chlorine (hypochlorite ions) in the mixed solution to turn into chlorine gas. Sulfamic acid can combine with free chlorine to become combined chlorine, but it is presumed that the local drop in pH causes chlorine gas to form before this reaction occurs.

[0050] TIFF0007689403000006.tif39166

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

[0052] Comparative Example 10 shows the test results of a calcium scale dissolving agent that contains citric acid as an organic acid and saccharin that forms combined chlorine. The amount of chlorine gas generated when the agent was mistakenly added was 8 ppm or more. The result was that the generation of chlorine gas was promoted, and no effective effect was confirmed.

[0053] Comparative Example 11 shows the test results of a calcium scale dissolving agent containing citric acid as an organic acid and thiourea, which forms combined chlorine. The amount of chlorine gas generated by mistaken addition was 16.0 ppm or more. The result was that the generation of chlorine gas was promoted, and no effective effect was confirmed.

[0054] In Comparative Examples 10 and 11, verification was carried out using compounds other than sulfamic acid that can form combined chlorine, but in none of them was the effect of reducing chlorine gas due to incorrect addition confirmed. This is expected to be because sulfamic acid can generate combined chlorine even in a liquid where organic acids coexist.

[0055] Comparative Example 12 shows the test results when citric acid, sulfamic acid, and ethylenediaminetetraacetic acid (EDTA) were mixed as organic acids. In a test in which calcium scale dissolving agent and 12% sodium hypochlorite were mixed in the wrong ratio of 1:4, 8.0 ppm of chlorine gas was generated. In addition, an increase in the liquid temperature was also confirmed. This is thought to be because EDTA reacts rapidly with hypochlorous acid, causing the liquid temperature to rise due to the heat of reaction, which promoted the generation of chlorine gas.

[0056] TIFF0007689403000007.tif49166

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

[0058] Example 19 shows the results of a test using ECO-200, a chlorine-based cleaning agent manufactured by Amtec Co., Ltd. The results of the test showed that the amount of chlorine gas generated was 0.1 ppm or less, and the generation of chlorine gas was very small when these cleaning agents were incorrectly added.

[0059] Example 20 shows the results of a test using a chlorine-based cleaning agent, HIDEC-TT manufactured by Amtec Co., Ltd. The results of the test showed that the amount of chlorine gas generated was 0.1 ppm or less, and the amount of chlorine gas generated was very small when these cleaning agents were incorrectly added.

[0060] Chlorine gas generation due to incorrect addition depends on the effective chlorine concentration of the chlorine-based cleaning agent. As the effective chlorine concentration decreases, the chlorine gas concentration also decreases.

[0061] TIFF0007689403000008.tif63166

[0062] Table 9 shows the calcium scale dissolving performance when the calcium scale dissolving agent of Example 3 was diluted. The calcium scale dissolving agent of Example 3 was diluted with ion-exchanged 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 to 25, it was confirmed that the calcium scale dissolving performance as a cleaning agent for dialysis equipment was sufficient, but in Comparative Example 13, the performance was not satisfactory. This is because the concentration of citric acid decreased as the dilution ratio increased, making it difficult to dissolve calcium scale. It is considered that the concentration of organic acid is appropriate to be 0.15% by mass to 2.00% by mass.

[0064] TIFF0007689403000009.tif25166 [Industrial Applicability]

[0065] The calcium scale dissolving agent according to the present invention is useful because it generates an extremely small amount of chlorine gas even when mixed with a chlorine-based cleaning agent, and therefore there is little danger even if the agent is mixed with the chlorine-based cleaning agent due to human error or the like.

Claims

1. A calcium scale dissolving agent for cleaning dialysis equipment, 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; A pH adjuster, The pH adjuster is at least one selected from sodium hydroxide, potassium hydroxide, and ammonia; At least one selected from the sulfamic acid or a salt thereof is present in an amount of 2.0% by mass to 20.0% by mass; At least one selected from the organic acid or a salt thereof is present in an amount of 15.0% by mass to 35.0% by mass; A calcium scale dissolving agent having a pH of 5.0 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. 3. The calcium scale dissolving agent according to claim 1 or 2, further comprising an anti-rust agent and / or an antiseptic agent.

4. Water, At least one selected from sulfamic acid or a salt thereof; At least one selected from an organic acid or a salt thereof; A pH adjuster, The pH adjuster is at least one selected from sodium hydroxide, potassium hydroxide, and ammonia; At least one selected from the sulfamic acid or a salt thereof is present in an amount of 2.0% by mass to 20.0% by mass; At least one selected from the organic acid or a salt thereof is present in an amount of 15.0% by mass to 35.0% by mass; A method for cleaning a dialysis device using a calcium scale dissolving agent having a pH of 5.0 to 6.5, comprising the steps of: A method for cleaning a dialysis device, comprising adding water to the calcium scale dissolving agent to dilute the agent so that the concentration of at least one selected from the organic acid or a salt thereof is 0.15% by mass to 2.00% by mass.

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