JP4602178B2 - Cleaning method - Google Patents

Description

  The present invention relates to a cleaning method for medical equipment, various industrial facilities, and the like, and more particularly to a cleaning method for an artificial dialysis apparatus.

  When cleaning equipment and medical equipment for producing pharmaceuticals and foods, it is common practice to combine cleaning with a chlorine-based disinfectant cleaner such as sodium hypochlorite aqueous solution and acid cleaning with an acidic aqueous solution. It has been broken. In addition, pipes provided with an ultrafiltration membrane or a microfiltration membrane for water treatment and the cleaning of these membranes are performed by combining acid cleaning with an acidic aqueous solution and alkali cleaning with an alkaline aqueous solution. Further, when disinfecting and cleaning medical equipment such as an artificial dialysis machine, sodium hypochlorite and acetic acid are known as the most frequently used cleaning agents.

  In particular, chlorinated disinfectants such as sodium hypochlorite have the ability to remove organic contaminants such as proteins and lipids as well as their strong bactericidal power, so they can be used in a wide range of applications such as washing of artificial dialysis machines. in use.

Cleaning wastewater using a chlorine-based disinfectant cleaner is desired to be disposed of with reduced active chlorine as much as possible due to environmental impact. From such a background, Patent Document 1 discloses a disinfection method in which a disinfectant is disinfected with an aqueous sodium hypochlorite solution, and then a reducing agent is added to the aqueous solution to decompose sodium hypochlorite with the reducing agent. ing. Patent Document 2 discloses that a reducing agent that makes an aqueous solution alkaline is used as a detoxifying agent for chlorine bleach disinfectant. On the other hand, acid cleaning using an organic acid such as acetic acid is performed for the purpose of scale removal, but the wastewater has a high BOD value and is not only concerned about the impact on the environment, but also dissolves and destroys concrete structures. There is a risk of causing serious accidents.
Japanese Patent Laid-Open No. 64-11552 Japanese Patent Laid-Open No. 10-235335

  Among various medical equipment and industrial equipment, in the cleaning of artificial dialysis machines, in addition to sterilization, it is excellent in scale removability, protein removability, and rust prevention, and after satisfying these requirements Although it is desired to perform sufficient wastewater treatment, it is difficult to say that the techniques of Patent Documents 1 and 2 sufficiently meet such demands.

  Therefore, the problem of the present invention is that the influence of the cleaning wastewater of the cleaning liquid using a chlorine-based disinfectant cleaning agent such as hypochlorite and the acidic cleaning liquid using an organic acid such as acetic acid on the environment while maintaining high cleaning performance. It is providing the washing | cleaning method which can reduce.

The present invention relates to a method for cleaning an object to be cleaned, in which step 2 is performed after performing step 1 below.
Step 1: Disinfecting and cleaning the object to be cleaned with the cleaning liquid 1 containing a chlorine-based disinfecting cleaning agent Step 2: Acid cleaning of the object to be cleaned with the cleaning liquid 2 whose pH is adjusted to 4 or less by adding a reducing agent to the cleaning liquid 1

  The present invention also relates to a cleaning agent kit comprising a chlorine-based disinfecting cleaning agent and a reducing agent used in the cleaning method of the present invention.

  The present invention provides a cleaning method that exhibits high detergency for medical devices such as an artificial dialysis apparatus, various industrial facilities, and the like, and that can reduce the environmental load of drainage. In the present invention, after the object to be cleaned is sterilized and cleaned with the cleaning liquid 1 containing a chlorine-based disinfecting cleaning agent, the acid of the object to be cleaned with the cleaning liquid 2 adjusted to pH 4 or less by adding a reducing agent to the cleaning liquid 1. Wash. This method can be effectively applied as a cleaning method for an artificial dialysis apparatus used in hospitals and the like.

  The cleaning method of the present invention can be sufficiently cleaned without using an organic acid such as acetic acid, which has been conventionally used for acid cleaning of medical equipment such as an artificial dialysis machine and various industrial facilities, and to the environment. The active chlorine discharge problem and the acid cleaning liquid drainage problem can be solved simultaneously.

<Cleaning liquid 1>
The cleaning liquid 1 contains a chlorine-based disinfectant cleaning agent. Chlorine disinfectants include alkali metal hypochlorites such as sodium hypochlorite and potassium hypochlorite, alkaline earth metal hypochlorites such as calcium hypochlorite, chlorinated isocyanuric acid Examples include chlorinated isocyanuric acid alkali metal salts such as sodium and potassium chlorinated isocyanurate, and chlorinated isocyanuric acid alkaline earth metal salts such as calcium chlorinated isocyanurate. Of these, alkali metal hypochlorites such as sodium hypochlorite and potassium hypochlorite are preferred, and sodium hypochlorite is more preferred. In general, sodium hypochlorite is produced by blowing chlorine gas into an aqueous sodium hydroxide solution and used in the form of an aqueous solution. Sodium hydroxide is present for stabilization of the aqueous solution. In the present invention, such an alkali component such as sodium hydroxide can be used while remaining in the cleaning liquid 1 as long as it does not affect the decrease in pH due to the reducing agent in step 2. The alkaline component is present in the cleaning liquid 1 to which the reducing agent is added in Step 2.

  In addition, the cleaning liquid 1 preferably has an effective chlorine concentration of 50 to 5000 ppm, more preferably 200 to 2500 ppm, from the viewpoint of the disinfecting cleaning effect, and the chlorine-based disinfecting cleaning agent is preferably blended to satisfy this concentration. . The effective chlorine concentration may be the above concentration from the start to the end of step 1, but at least the concentration at the start of step 1 (initial concentration) is preferably in the above range.

  Moreover, it is preferable from the point of protein removability that the washing | cleaning liquid 1 uses pH 7 or more, and also 9 or more. The pH can be adjusted by adding an appropriate alkaline agent and adjusting its content.

<Cleaning liquid 2>
The cleaning liquid 2 has a pH adjusted to 4 or less, preferably 3 or less, by adding a reducing agent to the cleaning liquid 1 used in Step 1 above, that is, the cleaning liquid 1 that has completed Step 1. By using the cleaning liquid 2 having a pH in this range, an acid cleaning effect can be obtained.

  Examples of the reducing agent include one or more selected from thiosulfate, bisulfite, hyposulfite, and ascorbate. More preferred is thiosulfate. The salt is preferably an alkali metal salt such as sodium or potassium. The reducing agent added in step 2 is 20 to 200 mol%, more preferably 25 to 150 mol%, particularly 30 to 100 mol% of the effective chlorine in the cleaning solution 1 and the resulting cleaning solution 2 is preferable from the viewpoint that the pH of 2 is easily lowered and an excellent acid cleaning effect is obtained. 25-30 mol% is also more preferable.

For example, when the reducing agent is sodium thiosulfate, when it is added to an aqueous sodium hypochlorite solution, chlorine is inactivated by the reaction of the following reaction formula (1) and reaction formula (2). As described above, since the alkaline component (such as sodium hydroxide) is present in the cleaning liquid 1, the reaction formula (1) proceeds. A trace amount of chlorine is present in equilibrium in the aqueous sodium hypochlorite solution, but when pH decreases in reaction formula (1), chlorine increases and reaction formula (2) proceeds. When the amount of sodium thiosulfate added is appropriately controlled, the pH is lowered by the acid generated in the reaction formula (2), and this can be used for acid cleaning. That is, in the present invention, chlorine inactivation and acid cleaning can be realized simultaneously.
Na ₂ S ₂ O ₃ + 4NaClO + 2NaOH → 2Na ₂ SO ₄ + 4NaCl + H ₂ O Reaction formula (1)
_{Na 2 S 2 O 3 + 4Cl} 2 + 5H 2 O → 2NaCl + 2H 2 SO 4 + 6HCl reaction formula (2)

<Other ingredients>
The cleaning liquid 1 and the cleaning liquid 2 can contain a surfactant, a chelating agent, and a rust inhibitor. These components may be added to each cleaning solution in advance, or may be added during each step.

  As the surfactant, anionic surfactants of alkyl sulfate, polyoxyethylene alkyl ether sulfate, alkylphenyl ether sulfate, alkyl diphenyl ether disulfonate, alkyl sulfonate, polyoxyethylene alkyl ether acetate; Non-polyoxyethylene alkyl ether, polyoxyethylene alkyl glyceryl ether, alkyl glyceryl ether, alkyl polyglycoside, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene sorbitan fatty acid ester, tetra fatty acid polyoxyethylene sorbite, alkylamine oxide, etc. Ionic surfactants; alkyldimethylaminoacetic acid betaines, alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium Betaines, fatty acid amidopropyl betaine, and amphoteric surfactants such as alkyl hydroxy sulfobetaine. As the surfactant, polyoxyethylene alkyl ether sulfate, alkylphenyl ether sulfate, and alkyl diphenyl ether disulfonate are preferable. When the object to be cleaned includes a filter that adsorbs the surfactant, it is preferable not to use the surfactant.

  When the surfactant is added in the middle of each step, a higher cleaning effect can be obtained by adding it at the earliest stage of each step. The surfactant content in the cleaning liquid 1 or in the cleaning liquid 2 is preferably 1 to 1000 ppm, more preferably 10 to 1000 ppm, and particularly preferably 50 to 500 ppm.

  Chelating agents include condensed phosphates (pyrophosphates, tripolyphosphates, tetrapolyphosphates, hexapolyphosphates), polyacrylates, acrylate-maleate copolymers, organic phosphonates ( Aminotri (methylenephosphonic acid) salt, 1-hydroxyethylidene 1,1-diphosphonate, ethylenediaminetetra (methylenephosphonic acid) salt, diethylenetriaminepenta (methylenephosphonic acid) salt, phosphonobutanetricarboxylate), etc. Can be mentioned. As the chelating agent, condensed phosphates and organic phosphonates are preferable. Further, the content of the chelating agent is preferably 1 to 1000 ppm, more preferably 10 to 500 ppm, and particularly preferably 20 to 200 ppm in the cleaning liquid 1 or the cleaning liquid 2.

  Antirust agents (some of which function as chelating agents) include silicates (orthosilicates, metasilicates, No. 1 silicates), phosphates, nitrates, the above organic phosphonates, oxalates, Examples thereof include borates. As a rust preventive agent, silicate and the said organic phosphonate are preferable. Further, the content of the rust inhibitor is preferably 0.001 to 200 ppm, more preferably 0.01 to 50 ppm, and particularly preferably 0.1 to 20 ppm in the cleaning liquid 1 or the cleaning liquid 2.

<Washing method>
Step 1 and Step 2:
In the present invention, after the object to be cleaned is sterilized and cleaned with the cleaning liquid 1 containing a chlorine-based disinfecting cleaning agent (step 1), a reducing agent is added to the cleaning liquid 1, that is, the cleaning liquid 1 that has completed step 1. Thus, the object to be cleaned is subjected to acid cleaning (step 2) with the cleaning liquid 2 adjusted to pH 4 or lower. In any step, the temperature of the cleaning liquid can be 15 to 95 ° C. Especially, 15-60 degreeC is preferable for process 1, and 30-60 degreeC is preferable for process 2. It is important that the cleaning solution and the object to be cleaned are in sufficient contact. In addition to the immersion method, in the case of line cleaning, a method of adjusting the flow rate at the time of passing and a method of adjusting the residence time after passing the solution can be used. . When the object to be cleaned is a closed system including a liquid feed line, a method of circulating and cleaning at an appropriate flow rate (for example, 0.1 to 50 liters / minute) is preferable. Air bubbling and ultrasonic waves can also be used in combination.

Moreover, in this invention, after performing the said process 2, it is preferable to perform the following process 3 further.
Step 3: Adjustment to pH 5 to 9 by adding a reducing agent and / or an alkaline agent to the cleaning liquid 2 that has finished Step 2.

  The pH in Step 3 can be adjusted using the reducing agent or alkali agent. When a reducing agent is used, it is 20 to 200 mol%, more preferably 25 to 150 mol%, based on the effective chlorine in the cleaning liquid 1, In particular, it is preferably used in a proportion of 30 to 100 mol% from the viewpoint of ease of pH adjustment and COD value of waste water. 30-45 mol% is also more preferable.

  When an alkaline agent is used in step 3, the pH can be adjusted by using 10 to 100 mol%, more preferably 12 to 75 mol%, particularly 15 to 50 mol%, based on the effective chlorine in the cleaning liquid 1. It is preferable from the viewpoint of ease of handling.

  The cleaning liquid 2 whose pH is adjusted in the range of 5 to 9 in the step 3 is preferable because it can be discarded as it is. Accordingly, the present invention may include discarding the cleaning liquid whose pH has been adjusted in step 3.

  Moreover, as an alkali agent, 1 or more types chosen from alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates, such as sodium carbonate and potassium carbonate, are mentioned. These alkaline agents are effective in adjusting the pH of the cleaning liquid 2 to about 5 to 9 neutral in Step 3, and the amount of the alkaline agent can be adjusted according to the effective chlorine concentration of the cleaning liquid 1 and the amount of reducing agent added. That's fine. In step 3, only the reducing agent or the alkaline agent may be added, or both the reducing agent and the alkaline agent may be added.

  In carrying out the present invention, the reducing agent in step 2 and the reducing agent and / or alkali agent in step 3 may be supplied to each cleaning liquid from a supply tank or the like as an aqueous solution containing these components, respectively. preferable. At that time, in step 3, chlorine in the cleaning liquid 2 has already been inactivated, and the pH can be easily increased even with a small amount of an alkaline component, so that an aqueous solution containing an alkaline component at a relatively low concentration can be used. On the other hand, as described above, the presence of a small amount of an alkaline component is acceptable also in Step 2, and thus an aqueous solution containing a reducing agent and an alkaline agent can be used in common in Step 2 and Step 3, thereby providing equipment. This is preferable because it can be further simplified. For example, when the reducing agent is sodium thiosulfate and the alkaline agent is sodium hydroxide, the reducing agent / alkaline agent is preferably 10/1 to 5/1 by weight ratio. Of course, since an alkali agent is essentially unnecessary in terms of adjusting the pH in step 2, each means for supplying the reducing agent in step 2, the reducing agent in step 3, and the alkali agent in step 3 is provided separately. It is also possible to supply. The temperature of step 3 is preferably 15 to 95 ° C, more preferably 15 to 60 ° C.

  A cleaning agent kit for the cleaning method of the present invention is composed of the chlorine-based disinfecting cleaning agent described above and a reducing agent that can be added to the cleaning liquid 1 containing the chlorine-based disinfecting cleaning agent and adjust the pH to 4 or less. Can do.

  In the cleaning method of the present invention, strong sterilizing power and excellent protein stain removing power can be obtained by using the cleaning liquid 1 containing a chlorine-based disinfectant cleaning agent in Step 1, and the cleaning liquid 2 having a pH of 4 or less is used in Step 2. Therefore, it is suitable for washing of an artificial dialysis apparatus because a good dissolving power of calcium carbonate can be obtained.

<Example 1>
Detergency was evaluated using a Nikkiso personal dialyzer DBG-01 as an object to be cleaned. A part of the line of the apparatus was replaced with a silicon tube contaminated under the following conditions, the silicon tube was removed at the end of steps 1, 2 and 3, and the contamination inside the tube was evaluated as follows. .

(1) Contamination condition of silicon tube About 40 cm of silicon tube was filled with a standard dialysate (Fuso Pharmaceutical Co., Ltd., kinderly solution AF-1), and was placed horizontally and allowed to stand for one week. After confirming the precipitation of calcium carbonate, the supernatant was discarded. Further, 0.5 mL of horse serum was dropped on the inner surface of the silicon tube, and the horse serum was thermally deteriorated and fixed by placing it horizontally at 50 ° C. for 24 hours. The amount of calcium carbonate deposited on the contaminated silicon tube obtained by this operation was 6.0 to 7.0 mg / m in terms of 1 m of the tube.

(2) Evaluation method (2-1) Evaluation method for protein stains After cleaning, the silicone tube is removed, and approximately 5 cm including the blood (horse serum) stain is vertically cut, and the protein adhesion state is confirmed by the amide black staining method. Visually evaluated.

(2-2) Evaluation method of calcium carbonate adhesion amount Fill the remaining silicon tube about 30cm with 0.1N hydrochloric acid solution, elute the adhered calcium carbonate, and measure the Ca concentration of the eluate. The amount of attached calcium carbonate was determined. The amount of adhesion was shown in units of mg / m in terms of 1 m of silicon tube.

(3) Cleaning and Evaluation Results In the following, the measurement of the cleaning solution pH and effective chlorine concentration in each step was performed by installing a sampling port immediately before the dirt evaluation silicon tube and sampling the circulating cleaning solution with a syringe.

  Chlorine-based detergent stock solution containing 7.2% by weight of sodium hypochlorite (as effective chlorine), 0.02% by weight of sodium metasilicate, and 1.4% by weight of sodium tripolyphosphate is 1.4% in water. The chlorine-based cleaning agent tank was filled with the primary diluted solution diluted twice. A chlorine-based cleaning agent primary dilution was supplied to a line to be cleaned filled with water purified by reverse osmosis (hereinafter referred to as RO water) to prepare cleaning liquid 1 having an effective chlorine concentration of 1010 ppm. The weight reduction of the primary diluent in the chlorine-based detergent tank was 10.57 g. The pH of the cleaning liquid 1 was 10.6. The cleaning liquid 1 was circulated through the line to be cleaned at a flow rate of 0.5 l / min for 40 minutes to perform cleaning at 36 ° C. (Step 1).

  Thereafter, 1.94 g of a reducing agent stock solution containing 20.0% by weight of sodium thiosulfate and 3.2% by weight of NaOH from the reducing agent supply tank (sodium thiosulfate is 32% of available chlorine in the cleaning liquid 1). .1 mol%) was injected into the same line to be cleaned. After 50 minutes, it was confirmed that the pH of the cleaning solution dropped to 2.75, and the effective chlorine concentration was below the detection lower limit of 0.05 ppm. This acidic solution was used as the washing solution 2 and circulated for 30 minutes at a flow rate of 0.5 l / min for acid washing at 36 ° C. for the purpose of removing scale components such as calcium carbonate (step 2).

  Thereafter, 1.90 g of the same reducing agent stock solution aqueous solution was injected into the same line to be cleaned and circulated under the same conditions as described above. The cleaning solution pH after 5 minutes was 6.12, and the effective chlorine concentration was less than the detection lower limit of 0.05 ppm. This washing solution had a pH of 6.05 after 2 hours (Step 3).

  After step 3 above, the silicon tube for dirt evaluation was removed, and as a result of measuring protein adhesion and calcium carbonate adhesion amount by the above method, protein adhesion was not recognized, and calcium carbonate adhesion amount was 0.01 mg / m, Most of the calcium carbonate adhering before washing was removed.

<Example 2>
Evaluation was performed in the same manner as in Example 1 by the following method. A primary diluted solution obtained by diluting an aqueous solution of a chlorine-based cleaning agent containing 7.0% by weight of sodium hypochlorite (as effective chlorine) and 0.02% by weight of sodium metasilicate 1.4 times with water, The detergent tank was filled. 10.68 g of a chlorine-based cleaning agent primary dilution was supplied to the line to be cleaned filled with RO water to prepare Cleaning Solution 1 having an effective chlorine concentration of 992 ppm. The pH of this cleaning liquid was 10.6, and cleaning was performed by heating to 60 ° C. while circulating through the line to be cleaned at a flow rate of 0.5 l / min for 40 minutes (step 1).

  Thereafter, 1.94 g of a reducing agent stock solution containing 20.0% by weight of sodium thiosulfate and 3.2% by weight of NaOH from the reducing agent supply tank (sodium thiosulfate is 32% of available chlorine in the cleaning liquid 1). .6 mol%) was injected into the same workpiece line. After 5 minutes, the pH of the cleaning solution was lowered to 2.75, and it was confirmed that the effective chlorine concentration was less than the detection lower limit of 0.05 ppm. This acidic liquid was used as the washing liquid 2 and circulated for 30 minutes at a flow rate of 0.5 liter / min for acid washing at 60 ° C. for the purpose of removing scale components such as calcium carbonate (step 2).

  Thereafter, 1.90 g of the same reducing agent stock solution aqueous solution was injected into the same line to be cleaned and circulated under the same conditions as described above. The cleaning solution pH after 5 minutes was 6.12, and the effective chlorine concentration was less than the detection lower limit of 0.05 ppm. This washing solution had a pH of 6.15 after 2 hours (Step 3).

  After step 3 above, the silicon tube for dirt evaluation was removed, and as a result of measuring protein adhesion and calcium carbonate adhesion amount by the above method, protein adhesion was not recognized, and calcium carbonate adhesion amount was 0.01 mg / m, Most of the calcium carbonate adhering before washing was removed.

<Example 3>
A chlorine-based cleaning agent tank was filled with a primary diluent obtained by diluting the same aqueous chlorine-based cleaning solution solution as in Example 1 with water 1.4 times. A cleaning solution 1 having an effective chlorine concentration of 480 ppm was prepared by supplying a chlorine-based cleaning agent primary dilution to a line to be cleaned filled with RO water. The weight reduction of the primary diluent in the chlorine-based detergent tank was 5.02 g. The pH of this cleaning solution was 10.4. The cleaning liquid 1 was circulated through the line to be cleaned at a flow rate of 0.5 l / min for 40 minutes to perform cleaning at 25 ° C. (Step 1).

  Thereafter, 1.61 g of a reducing agent stock solution containing 10.0% by weight of sodium thiosulfate, 1.5% by weight of NaOH, and 3.0% by weight of sodium bisulfite from the reducing agent supply tank (sodium thiosulfate 28.0 mol% with respect to available chlorine in the cleaning liquid 1) was injected into the same line to be cleaned. After 5 minutes, the pH of the cleaning solution was lowered to 3.02, and it was confirmed that the effective chlorine concentration was less than the detection lower limit of 0.05 ppm. This acidic liquid was used as the washing liquid 2 and circulated for 30 minutes at a flow rate of 0.5 liter / min for acid washing at 25 ° C. for the purpose of removing scale components such as calcium carbonate (step 2).

  Then, 1.60 g of the same reducing agent stock solution aqueous solution was injected into the same line to be cleaned and circulated under the same conditions as described above. The pH of the washing solution after 15 minutes was 5.95, and the effective chlorine concentration was less than the detection lower limit of 0.05 ppm (step 3).

  After step 3 above, the silicon tube for dirt evaluation was removed, and as a result of measuring protein adhesion and calcium carbonate adhesion amount by the above method, protein adhesion was not recognized, and calcium carbonate adhesion amount was 0.01 mg / m, Most of the calcium carbonate adhering before washing was removed.

<Example 4>
Steps 1 and 2 were performed in the same manner as in Example 1. After Step 2, the silicon tube for dirt evaluation was removed, and the amount of protein adhering and calcium carbonate adhering was measured by the above method. As a result, protein adhering was not observed and the amount of calcium carbonate adhering was 0.01 mg / m Most of the calcium carbonate that had previously adhered was removed.

<Example 5>
Steps 1 and 2 were performed in the same manner as in Example 2. After Step 2, the silicon tube for dirt evaluation was removed, and the amount of protein adhering and calcium carbonate adhering was measured by the above method. As a result, protein adhering was not observed and the amount of calcium carbonate adhering was 0.01 mg / m Most of the calcium carbonate that had previously adhered was removed.

<Example 6>
A chlorine-based cleaning agent tank was filled with a primary diluent obtained by diluting the same aqueous chlorine-based cleaning solution solution as in Example 1 with water 1.4 times. A cleaning solution 1 having an effective chlorine concentration of 1030 ppm was prepared by supplying a chlorine-based cleaning agent primary dilution to an object line to be cleaned filled with RO water. The weight reduction of the primary diluent in the chlorine-based detergent tank was 10.80 g. The pH of this cleaning solution was 10.6. This cleaning liquid 1 was circulated through the line to be cleaned at a flow rate of 0.5 l / min for 40 minutes to perform cleaning at 40 ° C. (step 1).

  Thereafter, from the reducing agent supply tank, 11.07 g of a reducing agent stock solution containing 2.9% by weight of sodium thiosulfate and 0.4% by weight of NaOH (26. 0 mol%) was injected into the same workpiece line. After 25 minutes, it was confirmed that the pH of the washing solution dropped to 2.78, and the effective chlorine concentration was less than the detection lower limit of 0.05 ppm. In order to remove scale components such as calcium carbonate, the acidic liquid was used as the cleaning liquid 2 and circulated for 30 minutes at a flow rate of 0.5 liter / min, and acid cleaning was performed at 40 ° C. (step 2).

  Thereafter, 8.53 g of the same reducing agent stock solution aqueous solution was injected into the same line to be cleaned and circulated under the same conditions as described above. The pH after 15 minutes was 6.52 and the effective chlorine concentration was less than the detection lower limit of 0.05 ppm (step 3).

<Example 7>
A chlorine-based cleaning agent tank was filled with a primary diluent obtained by diluting the same aqueous chlorine-based cleaning solution solution as in Example 1 2.0 times with water. A cleaning liquid 1 having an effective chlorine concentration of 880 ppm was prepared by supplying a chlorine-based cleaning agent primary dilution to a line to be cleaned filled with RO water. The weight reduction of the primary diluent in the chlorine-based detergent tank was 13.18 g. The pH of this cleaning solution was 10.2. This cleaning liquid 1 was circulated through the line to be cleaned at a flow rate of 0.5 l / min for 40 minutes to perform cleaning at 40 ° C. (step 1).

  Thereafter, from the reducing agent supply tank, 33.0 g of a reducing agent stock solution containing 0.8% by weight of sodium thiosulfate and 0.11% by weight of NaOH (sodium thiosulfate is 25% of the effective chlorine in the cleaning solution 1). 0.0 mol%) was injected into the same line to be cleaned. It was confirmed that the pH of the washing solution after 25 minutes was lowered to 2.95, and the effective chlorine concentration was less than the detection lower limit of 0.05 ppm. This acidic liquid was used as the washing liquid 2 and circulated for 30 minutes at a flow rate of 0.5 liter / min for acid washing at 40 ° C. for the purpose of removing scale components such as calcium carbonate (step 2).

  Thereafter, 26.0 g of the same reducing agent stock solution aqueous solution was poured into the same line to be cleaned and circulated under the same conditions as described above. The washing solution pH after 15 minutes was 5.80, and the effective chlorine concentration was less than the detection lower limit of 0.05 ppm (step 3).

<Test Example 1>
With respect to an aqueous solution containing 1000 ppm of sodium hypochlorite as an effective chlorine concentration, the amount (mol%) of the reducing agent used in Step 2 and the pH and effective chlorine concentration of the aqueous solution after adding the reducing agent were measured. The results are shown in Table 1.

* 1: mol% with respect to available chlorine in aqueous solution
* 2: pH after addition of reducing agent
* 3: Effective chlorine concentration after addition of reducing agent

  In the case of sodium thiosulfate, as can be seen from the reaction formulas (1) and (2), the chlorine content can be inactivated by adding 25 mol% with respect to the effective chlorine. Even in the results of Table 1, it can be confirmed that chlorine is not detected by addition of 25 mol% or more. With sodium bisulfite, sodium hyposulfite or ascorbic acid, the chlorine content can be inactivated by the addition amount of 100 mol%, 50 mol% or 100 mol%, respectively. In order to obtain an acidic liquid having a pH of 4 or less, it is not always necessary to add a reducing agent until all chlorine is inactivated. When the reducing agent in step 2 is sodium thiosulfate, an addition amount of 20 to 35 mol% with respect to effective chlorine is preferable. When the reducing agent in step 2 is sodium bisulfite, sodium hyposulfite or ascorbic acid, the addition amount is preferably 90 to 130 mol%, 40 to 60 mol% or 90 to 130 mol%, respectively, based on the effective chlorine. Of the aqueous solutions, those having a pH of 4 or less can be used as the cleaning liquid 2 of the present invention, but after step 2, the above-described reducing agent of at least mol% that finally inactivates all chlorine is added. Preferably (step 3). Even if the reducing agent is added excessively, it is easily lost by aeration in a septic tank or the like, so that there is no serious adverse effect on the environment.

<Test Example 2>
With respect to an aqueous solution (aqueous solution 1) containing 5020 ppm of sodium hypochlorite as an effective chlorine concentration, 20 mol% of reducing agent sodium thiosulfate (vs. effective chlorine) and 19.7 mol% of alkaline agent NaOH (vs. Effective chlorine) was added (aqueous solution 2), and the pH variation over time was measured when the same amounts of sodium thiosulfate and NaOH were added (aqueous solution 3). The results are shown in Table 2.

  When the same evaluation as in Example 1 was performed using the aqueous solution 1 and the aqueous solution 2 in Table 2, calcium carbonate and protein stains were almost completely removed.

Claims (10)

A method for cleaning an object to be cleaned, wherein Step 2 is performed after performing Step 1 below.
Step 1: Disinfecting and cleaning the object to be cleaned with the cleaning liquid 1 containing a chlorine-based disinfecting cleaning agent Step 2: Acid cleaning of the object to be cleaned with the cleaning liquid 2 whose pH is adjusted to 4 or less by adding a reducing agent to the cleaning liquid 1 The cleaning method according to claim 1, wherein after the step 2 is performed, the following step 3 is further performed.
Step 3: Adjustment to pH 5 to 9 by adding a reducing agent and / or an alkaline agent to the cleaning liquid 2 that has finished Step 2. The cleaning method according to claim 1 or 2, wherein the chlorine-based disinfectant cleaning agent is at least one selected from hypochlorite and chlorinated isocyanurate. The cleaning method according to any one of claims 1 to 3, wherein the reducing agent is at least one selected from thiosulfate, bisulfite, hyposulfite, and ascorbate. The cleaning method according to any one of claims 1 to 4, wherein an addition amount of the reducing agent in step 2 is 20 to 200 mol% with respect to the effective chlorine in the cleaning liquid 1. The cleaning method according to any one of claims 2 to 5, wherein an addition amount of the reducing agent in step 3 is 20 to 200 mol% with respect to the effective chlorine in the cleaning liquid 1. The cleaning method according to any one of claims 2 to 6, wherein the addition amount of the alkaline agent in step 3 is 10 to 100 mol% with respect to the effective chlorine in the cleaning liquid 1. The cleaning method according to claim 1, wherein the object to be cleaned is an artificial dialysis apparatus. The cleaning method according to any one of claims 1 to 8, wherein any one or more of the cleaning liquid 1 and the cleaning liquid 2 contains a rust inhibitor and / or a chelating agent. A cleaning agent kit comprising a chlorine-based disinfecting cleaning agent and a reducing agent used in the cleaning method according to claim 1.