JP6945324B2 - Washing method and neutralization composition - Google Patents

Description

The present invention relates to washing methods and neutralizing compositions.

Conventionally, a continuous washing machine has been used when washing a large amount of objects to be washed such as textile products. In a continuous washing machine, a pre-washing step of washing the object to be washed with washing water, a main washing step of further washing the object to be washed with washing water containing a bleaching agent such as hydrogen peroxide, and rinsing the object to be washed with water. A rinsing step and a finishing step of treating the object to be washed with finishing water are performed. In the continuous washing machine, when the object to be washed is poured into the washing water in the pre-washing step, the object to be washed is poured into the washing water together with water (hereinafter, referred to as "filled water" or "water to be washed").
In continuous washing machines, it is required to reduce the amount of water used for washing. Therefore, in a continuous washing machine, it is common practice to collect wastewater and use it in a pre-washing process. For example, attempts have been made to use the wastewater generated in the rinsing step, the finishing step, and the dehydration step as the input water.

By the way, when cleaning textile products such as sheets, lab coats, and surgical gowns used in hospitals (textile products used in hospitals are sometimes called hospital textile products), protein stains adhering to the object to be washed are removed. It is important to remove it. Among protein stains, removing blood stains is especially important. In order to efficiently remove blood stains from the object to be washed, a technique of adding a hydrogen peroxide reducing agent to a continuous washing machine has been proposed (for example, Patent Document 1). In the technique of Patent Document 1, a reducing agent of a bleaching agent is supplied to the recovered wastewater to reduce the residual concentration of hydrogen peroxide.

Japanese Unexamined Patent Publication No. 2001-120876

However, the conventional technique has not been sufficiently satisfactory in removing blood stains.
Therefore, an object of the present invention is to remove blood stains from the object to be washed more efficiently.

As a result of diligent studies by the present inventors, the mixture of the bleaching agent in the wastewater and the reducing agent thereof is insufficient, and the bleaching agent is not sufficiently reduced, so that blood stains on the object to be washed cannot be sufficiently removed. I got the finding. Based on this finding, the present inventors have completed the present invention.
The present invention has the following aspects.
[1] A first washing step of washing the object to be washed with a first washing water containing a first alkaline detergent, and
A second cleaning step of cleaning the object to be washed, which has undergone the first cleaning step, with a second washing water containing a second alkaline detergent and hydrogen peroxide.
A rinsing step of rinsing the object to be washed, which has undergone the second washing step, with water,
It has a finishing step of treating the object to be washed, which has undergone the rinsing step, with finishing water containing a neutralizing composition containing a sour agent and a hydrogen peroxide reducing agent.
A washing method in which the object to be washed is charged into the first washing water in the first washing step by using the input water containing drainage in the finishing step.
[2] The washing method according to [1], wherein the pH of the finishing water in the finishing step is 6.0 or more and 9.0 or less.
[3] The mass ratio of the hydrogen peroxide reducing agent to the sour agent in the neutralization composition ([hydrogen peroxide reducing agent] / [sour agent]) is 1.5 or more and 8.0 or less [1]. Alternatively, the washing method according to [2].
[4] The washing method according to any one of [1] to [3], wherein the concentration of hydrogen peroxide in the input water is 0 mass ppm or more and 10 mass ppm or less.
[5] The washing method according to any one of [1] to [4], wherein the concentration of hydrogen peroxide in the first washing water is 0 mass ppm or more and 10 mass ppm or less.

[6] Containing a sour agent and a hydrogen peroxide reducing agent,
The neutralizing composition used in the finishing step in the washing method according to any one of [1] to [5].
[7] Further containing water, the pH is 4.0 or more and 10.0 or less, and the mass ratio of the hydrogen peroxide reducing agent to the sour agent ([hydrogen peroxide reducing agent] / [sour agent]) is The neutralizing composition according to [6], which is 1.5 or more and 8.0 or less.

According to the washing method of the present invention, blood stains can be removed more efficiently from the object to be washed.

It is a flow figure explaining the washing method of this invention. It is a schematic diagram which shows an example of the continuous washing machine used in the washing method of this invention.

The washing method of the present invention includes a first washing step, a second washing step, a rinsing step, and a finishing step.
Hereinafter, an embodiment of the washing method of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the washing method of the present embodiment includes a first washing step S1, a second washing step S2, a rinsing step S3, and a finishing step S4.

The first washing step S1 is a step of washing the object to be washed with the first washing water. The first wash water contains a first alkaline detergent.
In the first cleaning step S1, stains such as protein stains adhering to the object to be washed are made to emerge from the object to be washed by the surface-active action and hydrolysis action of the first alkaline detergent contained in the first washing water. ,Remove. The first washing step S1 is also called a pre-washing step. The first alkaline detergent is not particularly limited, and known alkaline detergents can be used.
The dosage form of the alkaline detergent is not particularly limited, and may be a solid such as powder or a liquid. Examples of the alkaline agent contained in the first alkaline detergent include silicates such as sodium metasilicate, hydroxide compounds such as sodium hydroxide, carbonates such as sodium carbonate, and phosphates.
The first alkaline detergent may further contain a surfactant. Examples of the surfactant include conventionally known anionic surfactants, nonionic surfactants and the like.

The second cleaning step S2 is a step of cleaning the object to be washed that has undergone the first cleaning step S1 with the second cleaning water. The second wash water contains a second alkaline detergent and hydrogen peroxide.
In the second cleaning step S2, stains such as protein stains adhering to the object to be washed are caused by the surface-active action and hydrolysis action of the second alkaline detergent contained in the second washing water and the oxidizing action of hydrogen peroxide. Disassemble and remove. The second washing step S2 is also called a main washing step. The second alkaline detergent is not particularly limited, and a known alkaline detergent can be used. The second alkaline detergent may be the same as or different from the first alkaline detergent.
Examples of the second method for preparing the washing water include a method in which the second alkaline detergent and hydrogen peroxide are dispersed in water. Further, for example, the second method for preparing the washing water includes a compound that generates hydrogen peroxide in water (percarbonate such as sodium percarbonate, perborate such as sodium perborate, etc.) and a second method. A method of dispersing the alkaline detergent in water can be mentioned.

The rinsing step S3 is a step of rinsing the object to be washed that has undergone the second washing step S2 with water. As a result, the surfactant as a cleaning component, the alkaline agent, hydrogen peroxide as a bleaching component, and the like remaining on the object to be washed are removed. As the water used in the rinsing step (rinsing water), it is preferable to use water that does not contain an alkaline detergent and hydrogen peroxide. Further, as the rinsing water, the surplus water in the washing tub after the rinsing step may be used from the viewpoint of saving water.

The finishing step S4 is a step of treating the object to be washed that has undergone the rinsing step S3 with finishing water. The finishing water contains a neutralizing composition. The neutralizing composition contains a sour agent and a hydrogen peroxide reducing agent.
In the finishing step S4, the alkaline agent remaining on the object to be washed is neutralized by the sour agent. Further, the hydrogen peroxide remaining in the object to be washed is reduced by the hydrogen peroxide reducing agent.
The neutralization composition may be powdery or liquid. For example, as a neutralizing composition, a sour agent and a hydrogen peroxide reducing agent may be dispersed in water to prepare an aqueous solution (one-component type), and this aqueous solution may be supplied to the finishing water by a single liquid route. .. Further, as the neutralization composition, an aqueous solution of a sour agent and an aqueous solution of a hydrogen peroxide reducing agent may be prepared (two-component type), and both aqueous solutions may be supplied to the finishing water by two liquid routes. Alternatively, the sour agent and the hydrogen peroxide reducing agent may be stored in powder form, and a one-component or two-component aqueous solution may be prepared immediately before being supplied to the finishing water.

Sour agents are acidic substances that neutralize alkaline agents in alkaline detergents. The sour agent used in the finishing step S4 is not particularly limited, and a known sour agent can be used.
Known sour agents include organic acids such as citric acid, malic acid, succinic acid, oxalic acid, glycolic acid, tartrate acid, isocitrate, malonic acid, acetic acid, lactic acid, ascorbic acid and phytic acid, and inorganic acids such as phosphoric acid. Acid is mentioned. Of these, organic acids are preferable from the viewpoint of preventing embrittlement of fibers and corrosion of metals in the apparatus. Among the organic acids, citric acid and malic acid are preferable from the viewpoint of availability.

The hydrogen peroxide reducing agent reduces hydrogen peroxide. The hydrogen peroxide reducing agent used in the finishing step S4 is not particularly limited, and a known hydrogen peroxide reducing agent can be used. Known hydrogen peroxide reducing agents include thiosulfate, dithionate, sulfite, ascorbate, sodium bisulfite (sodium bisulfite), thiourea dioxide, sodium sulfoxyl and the like. Of these, sulfites are preferable, and sodium sulfite is more preferable, from the viewpoint of reducing power to hydrogen peroxide.

When the neutralizing composition is a one-component type, the mass ratio of the hydrogen peroxide reducing agent to the sour agent in the neutralizing composition ([hydrogen peroxide reducing agent] / [sour agent]) is 1.5 or more and 8.0. It is preferably 1.5 or more and 3.5 or less, and more preferably 1.5 or more and 2.5 or less. When the mass ratio is at least the lower limit value, the influence of acidity by the sour agent can be suppressed, and the decomposition of the hydrogen peroxide reducing agent can be suppressed. When the mass ratio is not more than the upper limit value, the liquid stability of the neutralizing composition is improved without forming precipitates at a low temperature.

The blending ratio of the sour agent in the neutralizing composition is determined according to the type of sour agent used, and is preferably 1.0% by mass or more and 10.0% by mass or less, preferably 5.0% by mass or more. More preferably, it is 10.0% by mass or less. When the blending ratio of the sour agent is at least the lower limit value, the neutralizing ability of the sour agent can be ensured. When the blending ratio of the sour agent is not more than the upper limit value, the influence of acidity by the sour agent can be suppressed and the decomposition of the hydrogen peroxide reducing agent can be suppressed.
The blending ratio of the hydrogen peroxide reducing agent in the neutralization composition is determined according to the type of the hydrogen peroxide reducing agent. For example, it is preferably 10% by mass or more and 30% by mass or less, and 15% or more and 25% or less. Is more preferable. When the blending ratio of the hydrogen peroxide reducing agent is at least the lower limit value, the influence of decomposition of the hydrogen peroxide reducing agent by an acidic substance such as a sour agent or an oxidizing substance such as oxygen can be suppressed. When the blending ratio of the hydrogen peroxide reducing agent is not more than the upper limit value, it is possible to suppress the inhibition of the neutralizing ability of the sour agent by the hydrogen peroxide reducing agent.
The blending ratio of water in the neutralization composition is determined according to the blending ratio of the alkaline detergent and hydrogen hydrogen used in the washing method, and is preferably 65% by mass or more and 85% by mass or less, for example. More preferably, it is 70% by mass or more and 80% by mass or less.

The pH of the neutralizing composition is preferably 4.0 to 10.0, more preferably 4.5 to 6.8, and particularly preferably 4.5 to 6.2. When the pH of the neutralizing composition is at least the lower limit, the decomposition of the hydrogen peroxide reducing agent can be suppressed. Further, when the pH of the neutralizing composition is not more than the upper limit value, it is possible to prevent the object to be washed from causing alkaline burning due to insufficient rinsing, and the liquid of the neutralizing composition does not generate precipitates at a low temperature. Stability is improved.

The neutralizing composition used in the finishing step S4 may contain an optional component in addition to the sour agent and the hydrogen peroxide reducing agent. Optional ingredients include, for example, surfactants, chelating agents, dispersants, water-soluble solvents, silicones, optical brighteners, antibacterial agents, deodorants, fragrances, preservatives, UV absorbers, smoothing agents, and anti-shrink agents. , Washing wrinkle inhibitor, drape preservative, ironing improver, whitening agent, whitening agent, fabric softening clay, antistatic agent, dye transfer inhibitor, polymer dispersant, stain remover, scum dispersant , Dye fixers, anti-fading agents, stain removers, fiber surface modifiers, enzymes such as catalase, foam suppressants, anti-staining agents, non-ionic polymer compounds and the like.

Examples of the method for producing the neutralizing composition include the following methods. First, an aqueous hydrogen peroxide reducing agent solution is prepared by dissolving a hydrogen peroxide reducing agent (for example, sodium sulfite) in water such as soft water. A mixed aqueous solution is prepared by adding a sour agent (for example, malic acid) to the hydrogen peroxide reducing agent aqueous solution and dissolving it. By filtering the obtained mixed aqueous solution, a neutralizing composition as a product is obtained.

Next, an embodiment of the washing method of the present invention will be described with reference to the drawings.
The continuous washing machine 1000 of FIG. 2 includes a washing main body 100, a detergent dilution / dissolution tank 200, a bleach dilution tank 300, a neutralization composition tank 400, a finishing agent tank 500, a recycling tank 600, and dehydration recovery. A water recycling tank 700 and a washing object input water tank 800 are provided.

The continuous washing machine 1000 includes a washing main body 100. The washing main body 100 may be a double drum type having an inner body for storing the object to be washed and rotating in the outer body for storing the washing liquid, or may be composed of a single rotating body. It may be a single drum type. In the washing main body 100, the first washing tubs 1 to 12 washing tubs 12 including a plurality of outer and inner bodies are arranged concentrically. The washing main body 100 includes a pre-washing unit, a main washing unit, a rinsing unit, and a finishing unit.

The pre-washing unit includes a first washing tub (pre-washing first tub) 1, a second washing tub (pre-washing second tub) 2, and a third washing tub (pre-washing third tub) 3. The main washing unit includes the 4th washing tub (1st main washing tub) 4, the 5th washing tub (2nd main washing tub) 5, the 6th washing tub (3rd main washing tub) 6, and the 7th washing tub. It includes a washing tub (main washing fourth tub) 7 and an eighth washing tub (main washing fifth tub) 8. The rinsing unit includes a ninth washing tub (rinsing first tub) 9, a tenth washing tub (rinsing second tub) 10, and an eleventh washing tub (rinsing third tub) 11. The finishing unit includes a twelfth washing tub (finishing tub) 12. The number of washing tubs that make up the pre-washing unit, the number of washing tubs that make up the main washing unit, the number of washing tubs that make up the rinsing unit, and the number of washing tubs that make up the finishing unit are shown in FIG. It is not limited to the number in the structure shown.

The washing main body 100 is intermittently and intermittently driven by the driving device 120 in a counterclockwise direction and a clockwise direction with the central axis 130 of the washing main body 100 as the center of rotation in a certain rotation angle range. NS. The drive device 120 includes a motor, a gearbox, and the like. The washing main body 100 includes a spiral chute for transporting the object to be washed between adjacent mutual washing tubs of the first washing tub 1 to the twelfth washing tub 12. The spiral chute is formed to transfer the object to be washed from each washing tub to an adjacent downstream washing tub. Therefore, when the washing tub rotates 360 °, the object to be washed is transferred to the washing tub downstream. The washing water, rinsing water, and finishing water are parallel flow and / or counter flow (batch flow and / or counter flow) to the object to be washed, and the prewash / main wash / main wash of the object to be washed is performed inside each washing tub. Rinse in sequence.

Referring to FIG. 2, the washing main body 100 includes a dehydrator 13 connected to the twelfth washing tub 12 and a washing object input port 14 provided in the first washing tub 1. The washing main body 100 includes a detergent dilution and dissolution tank 200 and a bleach dilution tank 300. The detergent dilution / dissolution tank 200 is a tank for storing the detergent, and the stored detergent may be diluted with water. The bleach diluting tank 300 is a tank for storing hydrogen peroxide or a bleaching agent which is a hydrogen peroxide product, and the stored bleaching agent may be diluted with water. The detergent diluting and dissolving tub 200 and the washing main body 100 are configured so that the detergent diluted in the detergent diluting and dissolving tub 200 is transferred to the first washing tub 1 and the fourth washing tub 4 by the detergent diluting liquid transfer pump. The bleach diluted in the bleach dilution tank 300 is configured to be transferred to the fifth washing tub 5 by the bleach diluent transfer pump.

In order for the dehydration recovery water recycling tank 700 to recover the dehydration recovery water from the 12th washing tub 12 and to recover the dehydration recovery water from the dehydrator 13, drain pipes 112 and 113 are provided in the 12th washing tub 12 and the dehydrator 13. Each is connected via.

The recycling tank 600 is connected to the ninth washing tub 9 via a drain pipe 109. Further, the recycling tank 600 is connected to the eighth washing tub 8 via a supply pipe 601 provided with a recovered water transfer pump 610. The recycling tank 600 can collect washing water from the ninth washing tub 9. In addition, the recycling tank 600 can transfer the collected washing water to the eighth washing tub 8. The recycling tank 600 is not limited to the ninth washing tub 9, and may be connected to at least one of the ninth washing tub 9, the tenth washing tub 10, and the eleventh washing tub 11. It is particularly preferable that the recycling tank 600 is connected to the ninth washing tub 9.

The wash object input water tank 800 is provided to transfer the wash object input water to the wash object input port 14 by the operation of the wash object input water transfer pump 810. The reclaimed water tank 600 and the object input water tank 800 are provided with a supply pipe 601 provided with a reclaimed water input amount adjusting valve (not shown) for the discharged liquid discharged from the reclaimed water tank 600 by the operation of the reclaimed water transfer pump 610. It is configured to be transferred to the eighth washing tub 8 via the operation of the recovered water transfer pump 620 and transferred to the object input water tank 800. In the dehydration recovery water recycling tank 700 and the wash object input water tank 800, the discharge liquid discharged from the dehydration recovery water recycling tank 700 is transferred to the wash object input water tank 800 by the operation of the dehydration recovery water transfer pump 710. It is composed of.

In such a continuous washing machine 1000, the washing water, the rinsing water, and the finishing water are parallel and / or countercurrent (batch flow and / or counter flow) with respect to the object to be washed, and the object to be washed is the first. It moves from the washing tub 1 to the eleventh washing tub 11 in order. Further, in the continuous washing machine 1000, the object to be washed is pre-washed in the first washing tub 1 to the third washing tub 3 (pre-washing unit), and the fourth washing tub 4 to the eighth washing tub 8 (main washing unit) are performed. ) Is used to perform the main washing of the object to be washed, the ninth washing tub 9 to the eleventh washing tub 11 are used to rinse the object to be washed, and the dehydrator 13 is configured to dehydrate the object to be washed.

Next, the washing method of the embodiment using the continuous washing machine 1000 of FIG. 2 will be described with reference to the drawings. In the washing method of the embodiment using the continuous washing machine 1000 of FIG. 2, washing water, rinsing water, and finishing water flow in the direction of the object to be washed.
First, water is supplied from the recycling tank 600 to the eighth washing tub 8. The water supplied to the eighth washing tub 8 flows from the eighth washing tub 8 toward the first washing tub 1, and a predetermined amount of water is supplied to each washing tub of the first washing tub 1 to the second washing tub 8. Will be done. An alkaline detergent (first alkaline detergent) is supplied from the detergent dilution / dissolution tank 200 to the first washing tub 1.
In the first washing tub 1 to the third washing tub 3 (pre-washing unit), the first alkaline detergent and water are mixed to become the first washing water. The pH of the first wash water is preferably, for example, 9 to 13. When the pH of the washing water is at least the lower limit value, the washing effect of the alkaline detergent can be sufficiently exhibited. A higher pH of the washing water can be expected to have a higher effect, but even if the pH exceeds 13, a significant improvement in the washing effect cannot be expected. Also, if the pH exceeds 13, it is uneconomical because it requires a lot of rinsing water and a neutralizing agent.
The temperature of the first washing water is preferably 15 ° C. or higher and 60 ° C. or lower, more preferably 30 ° C. or higher and 55 ° C. or lower, and particularly preferably 46 ° C. or higher and 55 ° C. or lower. When the temperature of the first washing water is equal to or higher than the lower limit, it is not necessary to perform excessive cooling when reusing the used water, and it is necessary to provide an eco-friendly continuous washing method that is efficient in terms of water saving and energy saving. Can be done. When the temperature of the first washing water is not more than the upper limit value, the denaturation of protein stains due to the high temperature can be suppressed.

The object to be washed is charged together with the input water from the object input port 14 into the first washing tub 1 of the washing main body 100 (operation for charging the object to be washed).
In the first washing tub 1, the object to be washed and the first washing water are shaken for a predetermined time to wash the object to be washed.
As a result, some protein stains, oil stains, etc. emerge from the object to be washed and are removed.
After that, the first washing tub 1 is rotated 360 ° to transfer the object to be washed to the second washing tub 2. In this way, the objects to be washed are sequentially washed in the first washing tub 1 to the third washing tub 3 (first washing step). The rocking time in each of the first washing tub 1 to the twelfth washing tub 12 is preferably 1 minute or more and 6 minutes or less, more preferably 1.5 minutes or more and 5 minutes or less, and particularly preferably 2 minutes or more and 4 minutes or less. preferable.
A part of the first washing water in the first washing tub 1 is discharged from the first washing tub 1 through the drain pipe 101 as drainage E1. Further, a part of the first washing water in the second washing tub 2 is discharged from the second washing tub 2 through the drain pipe 102 as drainage E2, and is one of the first washing waters in the third washing tub 3. The portion is discharged as drainage E3 from the third washing tub 3 through the drainage pipe 103.
In this way, the objects to be washed are sequentially washed in the first washing tub 1 to the third washing tub 3 (pre-washing unit) (first washing step).

An alkaline agent (second alkaline agent) is supplied from the detergent dilution / dissolution tank 200 to the fourth washing tub 4. Hydrogen peroxide is supplied from the bleach dilution tank 300 to the fifth washing tub 5. In this way, in the 4th washing tub 4 to the 8th washing tub 8 (main washing unit), the second alkaline detergent, hydrogen peroxide, and water are mixed to become the second washing water. The concentration of hydrogen peroxide in the second washing water is preferably 10 mass ppm or more and 1000 mass ppm or less, and more preferably 100 mass ppm or more and 800 mass ppm or less. In particular, the concentration of hydrogen peroxide in the washing water of the fifth washing tub 5 is preferably 300 mass ppm or more and 700 mass ppm or less from the viewpoint of the bleaching effect of the object to be washed.
The pH of the second wash water is preferably, for example, 9 to 13. When the pH of the washing water is equal to or higher than the lower limit, the bleaching effect of hydrogen peroxide is enhanced. A higher pH of the washing water can be expected to have a higher effect, but even if the pH exceeds 13, a significant improvement in the washing effect cannot be expected. Also, if the pH exceeds 13, it is uneconomical because it requires a lot of rinsing water and a neutralizing agent. The temperature of the second washing water is preferably 50 ° C. or higher and 90 ° C. or lower, and more preferably 70 ° C. or higher and 90 ° C. or lower. When the temperature of the second washing water is equal to or higher than the lower limit, the effect of hydrogen peroxide can be fully exerted. A higher temperature of the second washing water can be expected to have a higher effect, but even if the temperature of the second washing water exceeds 90 ° C., a significant improvement in the washing effect cannot be expected, which is not economical. For example, a washing method of 80 ° C. or higher and 10 minutes or longer is more preferable because it satisfies conditions having a bactericidal effect and the like.

The object to be washed is transferred from the third washing tub 3 to the fourth washing tub 4. In the fourth washing tub 4, the object to be washed and the second washing water are shaken for a predetermined time to wash the object to be washed. As a result, it is possible to remove stains (for example, blood stains) that remain floating from the object to be washed in the first cleaning step. After that, the object to be washed in the 4th washing tub 4 is transferred to the 5th washing tub 5. In this way, the objects to be washed are sequentially washed in the 4th washing tub 4 to the 8th washing tub 8 (main washing unit) (second washing step).

Fresh water W1 (rinsing water) is supplied to the eleventh washing tub 11. The water supplied to the 11th washing tub 11 flows from the 11th washing tub 11 to the 9th washing tub 9, and a predetermined amount of water is supplied to each washing tub of the 9th washing tub 9 to the 11th washing tub 11. Will be done. Examples of the water W1 include tap water and well water, water from which iron compounds and manganese compounds have been removed by water treatment, water that has passed through a water softener that softens water by ion exchange, and the like.

The object to be washed in the 8th washing tub 8 is transferred to the 9th washing tub 9. In the ninth washing tub 9, the object to be washed and the rinsing water are shaken for a predetermined time to rinse the object to be washed.
The rinsing water in the ninth washing tub 9 is discharged from the drain pipe 109 and flows into the recycling tank 600. The inclined barrier between the 8th washing tub 8 and the 9th washing tub 9 is formed higher than the other inclined barriers. Therefore, it is difficult for the water in the ninth washing tub 9 to directly flow into the eighth washing tub 8.

The object to be washed rinsed in the ninth washing tub 9 is sequentially transferred to the tenth washing tub 10 and the eleventh washing tub 11 and rinsed. During this time, the alkaline agent and hydrogen peroxide remaining on the object to be washed are eluted.
As a result, the residual concentration of the alkaline agent, hydrogen peroxide, etc. in the object to be washed is reduced (rinsing step).

Fresh water W2 is supplied to the twelfth washing tub 12. The neutralizing composition is supplied from the neutralizing composition tank 400 to the water in the twelfth washing tub 12, and the finishing agent is supplied from the finishing agent tub 500 to the twelfth washing tub 12. In the twelfth washing tub 12, the neutralizing composition, the finishing agent and water are mixed to obtain finishing water. This finishing water contains a sour agent and a hydrogen peroxide reducing agent contained in the neutralizing composition.

The object to be washed in the 11th washing tub 11 is transferred to the 12th washing tub 12. In the twelfth washing tub 12, the object to be washed and the finishing water are shaken. As a result, the residual concentration of the alkaline agent, hydrogen peroxide, etc. in the object to be washed is reduced (finishing step).

The finishing agent supplied to the twelfth washing tub 12 is not particularly limited, and known finishing agents can be used. Examples of known finishing agents include softeners and sizing agents.
The pH of the finishing water in the finishing step is preferably 6.0 or more and 9.0 or less, and more preferably 7.0 or more and 8.0 or less. When the pH of the finishing water is at least the lower limit, the decomposition of the hydrogen peroxide reducing agent can be suppressed. Further, when the pH of the finishing water is not more than the upper limit value, it is possible to prevent the object to be washed from causing alkaline burning due to insufficient rinsing after washing. Alkaline burning means that the object to be washed turns yellow or the like due to the residual alkaline component such as an alkaline agent in the object to be washed.

The amount of the neutralizing composition supplied to water (that is, the content of the neutralizing composition in the finishing water) sufficiently neutralizes the alkaline agent remaining in the object to be washed and sufficiently neutralizes hydrogen peroxide. Any amount may be used as long as it is reduced.
The shaking time of the object to be washed and the finishing water in the 12th washing tub 12 is preferably 1 minute or more and 6 minutes or less, more preferably 1.5 minutes or more and 5 minutes or less, and particularly preferably 2 minutes or more and 4 minutes or less. The rocking time after charging the drug is preferably 1 minute or more. When the swing time is not more than the upper limit value, the work efficiency of the finishing process can be improved. When the shaking time is at least the lower limit value, the object to be washed and the neutralizing composition can be sufficiently agitated. As a result, the hydrogen peroxide remaining on the object to be washed can be efficiently neutralized. In addition, hydrogen peroxide remaining in the object to be washed can be efficiently reduced. As a result, the concentration of hydrogen peroxide in the finishing water after the finishing step can be reduced.

The finishing water is appropriately discharged from the 12th washing tub 12 through the drain pipe 112, and flows into the dehydrated recovery water recycling tank 700.
The concentration of hydrogen peroxide in the finishing water discharged from the twelfth washing tub 12 is preferably 0 mass ppm or more and 10 mass ppm or less, more preferably 0 mass ppm or more and 5 mass ppm or less, and 0 mass ppm or less. It is more preferably ppm or more and 2 mass ppm or less, and particularly preferably 0 mass ppm or more and 1 mass ppm or less. When the concentration of hydrogen peroxide in the finishing water discharged from the twelfth washing tub 12 is 10 mass ppm or less, the discharged finishing water can be effectively reused as input water.
The method for measuring the concentration of hydrogen peroxide in the finishing water is not particularly limited, and the measurement can be performed using a known measuring instrument. Examples of known measuring instruments include test papers containing a color-developing reagent (for example, a porphyrin compound) that causes a color reaction with hydrogen peroxide.

The finishing water of the twelfth washing tub 12 passes through the inclined barrier between the washing tubs and flows into the ninth washing tub 9 to the eleventh washing tub 11. Therefore, the rinsing water in the 9th washing tub 9 to the 11th washing tub 11 contains a sour agent and a hydrogen peroxide reducing agent. Since this sour agent neutralizes the alkaline detergent, it reduces the residual concentration of the alkaline agent in the object to be washed. Further, since the hydrogen peroxide reducing agent neutralizes hydrogen peroxide, the residual concentration of hydrogen peroxide in the object to be washed is reduced. The concentration of hydrogen peroxide in the rinsing water of the ninth washing tub 9 to the eleventh washing tub 11 is preferably 0 mass ppm or more and 100 mass ppm or less, and more preferably 0 mass ppm or more and 10 mass ppm or less. In particular, it is preferable that the concentration of hydrogen peroxide in the rinsing water discharged from the ninth washing tub 9 is 0 mass ppm or more and 2 mass ppm or less from the viewpoint of reuse as input water.

The washing method of the embodiment is characterized in that the object to be washed is treated with finishing water containing a hydrogen peroxide reducing agent in the finishing step. In the finishing step, the object to be washed and the finishing water are shaken for a predetermined period of time. Therefore, the hydrogen peroxide reducing agent permeates the inside of the object to be washed, and the hydrogen peroxide remaining in the object to be washed can be reduced. As a result, the concentration of hydrogen peroxide in the finishing water after the finishing step can be reduced to a desired value.

In the continuous washing machine 1000 of FIG. 2, the sour agent and the hydrogen peroxide reducing agent which are the components of the neutralizing composition may be mixed in advance in the neutralizing composition tank 400. Alternatively, the sour agent and the hydrogen peroxide reducing agent may be supplied to the twelfth washing tub 12 via two pipes without being mixed in the neutralization composition tub 400 and mixed in the finishing water. good. Above all, it is preferable that the neutralizing composition is an aqueous solution containing a sour agent, a hydrogen peroxide reducing agent, and water from the viewpoint of sharing of piping and supply equipment and from the viewpoint of economy.

The object to be washed in the twelfth washing tub 12 is transferred to the dehydrator 13. The object to be washed is dehydrated by the dehydrator 13. Then, the object to be washed is transferred to a dryer (not shown) and dried. The water generated in the dehydrator 13 is discharged through the drain pipe 113 and flows into the dehydrated recovery water recycling tank 700.
The concentration of hydrogen peroxide in the water generated in the dehydrator 13 is preferably 0 mass ppm or more and 10 mass ppm or less, more preferably 0 mass ppm or more and 5 mass ppm or less, and 0 mass ppm or more and 2 mass ppm or less. It is more preferably ppm or less, and particularly preferably 0 mass ppm or more and 1 mass ppm or less. When the concentration of hydrogen peroxide in the finishing water discharged from the dehydrator 13 is 10 mass ppm or less, the discharged finishing water can be effectively reused as input water.

The water that has flowed into the dehydrated recovery water recycling tank 700 is supplied to the object input water tank 800 via the supply pipe 701. The water collected in the recycling tank 600 is also supplied to the object input water tank 800 via the supply pipe 602. Water W3 is supplied to the object input water tank 800 to be washed. Water with a reduced concentration of hydrogen peroxide is stored in the water input tank 800 for washing.
Examples of water W3 include tap water and well water, water from which iron compounds and manganese compounds have been removed by water treatment, water that has passed through a water softener that softens water by ion exchange, and the like.

The ninth washing tub 9 is closer to the fifth washing tub 5 to which hydrogen peroxide is supplied than the twelfth washing tub 12. Therefore, the water recovered from the 9th washing tub 9 to the recycling tank 600 has a higher hydrogen hydrogen concentration than the water recovered from the 12th washing tub 12 to the dehydrated recovered water recycling tank 700. In the continuous washing machine 1000, the water supplied from the dehydrated recovered water recycling tank 700 by the recovered water transfer pump 620 so that the concentration of hydrogen peroxide in the water of the object input water tank 800 does not exceed a predetermined value. The flow rate of water supplied from the recycling tank 600 is adjusted with respect to the flow rate of.

The water in the wash object input water tank 800 is charged into the wash object input port 14 as input water. Specifically, the input water is input to the object to be washed input port 14 via the supply pipe 801 by the object input water transfer pump 810. The water input into the object to be washed 14 flows into the first washing tub 1 while entraining the object to be washed. In this way, the water recovered in the recycling tank 600 and the dehydrated recovered water recycling tank 700 is reused as the input water for the first washing tub 1.

Blood stains on the laundry are easily oxidized by hydrogen peroxide. Oxidized blood stains have a problem that they are difficult to be removed from the object to be washed due to protein denaturation. In the present embodiment, the concentration of hydrogen peroxide in the input water is preferably 0 mass ppm or more and 10 mass ppm or less, more preferably 0 mass ppm or more and 5 mass ppm or less, and 0 mass ppm or more 2 It is more preferably 0 mass ppm or more, and particularly preferably 1 mass ppm or less. When the concentration of hydrogen peroxide in the input water is 10 mass ppm or less, it is possible to suppress the oxidation of blood stains on the object to be washed by hydrogen peroxide when the input water comes into contact with the object to be washed.
For the same reason, the concentration of hydrogen peroxide in the first washing water used in the first washing tub 1 is preferably 0 mass ppm or more and 10 mass ppm or less, and is 0 mass ppm or more and 5 mass ppm or less. It is more preferably 0 mass ppm or more and 2 mass ppm or less, and particularly preferably 0 mass ppm or more and 1 mass ppm or less. By adjusting both the concentration of hydrogen peroxide in the input water and the concentration of hydrogen peroxide in the first wash water within a preferable numerical range, it is more certain that the blood stains on the object to be washed are oxidized by hydrogen peroxide. Can be suppressed.
The oxidation of blood stains by hydrogen peroxide depends on the temperature, and the higher the temperature, the faster the oxidation. Therefore, it is preferable to adjust the concentration of hydrogen peroxide to be lower as the temperature of the input water is higher.
On the contrary, when the concentration of hydrogen peroxide is low, the temperature of the input water can be set high. For example, when the concentration of hydrogen peroxide in the input water is 0 mass ppm or more and 2 mass ppm or less, the temperature of the input water is preferably 40 ° C. or higher and 55 ° C. or lower, and 46 ° C. or higher and 55 ° C. or lower. More preferred. If the temperature of the input water to be washed is set high, the overall energy cost can be reduced by recycling the water including heat exchange.
In the washing method of the embodiment described above, the washing water, the rinsing water, and the finishing water flow in the direction of the object to be washed, but the washing method of the present invention is not limited to this embodiment, and the washing water and the rinsing water are not limited to this embodiment. , The finishing water may flow parallel to the object to be washed.

According to the washing method of the present invention described above, since the object to be washed is treated with finishing water containing a hydrogen peroxide reducing agent in the finishing step, blood stains can be removed from the object to be washed more efficiently. In addition, the neutralizing composition of the present invention is suitable for removing blood stains in the washing method of the present invention, and can be used as a blood cleaning enhancer.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following description.

(Example 1)
In Example 1, the blood-contaminated cloth was washed using a continuous washing machine. The continuous washing machine used was the same as the continuous washing machine 1000 in FIG. 2, except that the number of washing tubs was 16. The washing method was carried out according to the washing method of the embodiment. The water flow direction was the same as that of the object to be washed (referred to as parallel flow, batch flow or co-flow). The classification of the washing tub was as follows. 1st washing tub to 3rd washing tub: 1st washing step (pre-washing step), 4th washing tub to 10th washing tub: 2nd washing step (main washing step), 11th washing tub to 11th 15 washing tubs: rinsing process, 16th washing tub: finishing process. In Example 1, the drainage from the 16th washing tub and the drainage from the dehydration step were reused as the input water to the 1st washing tub.
As a cleaning agent, HAK detergent (manufactured by Lion Hygiene Co., Ltd.) 1.0% owf was supplied to the first washing tub. At that time, the pH of the washing water in the first washing tub was 11.5. 0.16% hydrogen peroxide as a bleaching agent was supplied to the fourth washing tub. At that time, the hydrogen peroxide concentration in the fourth washing tub was 400 mass ppm. As a neutralizing composition, a composition of 20% by mass of sodium sulfite, 5% by mass of malic acid and 75% by mass of water was supplied to the 16th washing tub (finishing tub). When 350 g of the composition of 20% by mass of sodium sulfite, 5% by mass of malic acid and 75% by mass of water was supplied, the concentration of hydrogen peroxide in the finishing water of the 16th washing tub was 0% by mass. A blood-contaminated cloth (EMPA111) was used as the object to be washed, and 60 kg of the object to be washed was prepared together with other sheets. Further, in the pre-washing step, the washing temperature was 45 ° C. and the washing time was 6 minutes. Further, in the main washing step, the washing temperature was 80 ° C. and the washing time was 14 minutes. In addition, "% owf" indicates a percentage with respect to the mass of the object to be washed.
The hydrogen peroxide concentration was measured using a semi-quantitative ion test peroxide 100 or a semi-quantitative ion test peroxide 1000 (manufactured by MACHEREY-NAGEL).
As a method for evaluating the blood detergency, one sheet sewn with five blood-contaminated cloths (EMPA111: manufactured by EMPA TESTMATERIAL) cut into 5 cm × 5 cm was washed. The reflectance of the five detergency evaluation cloths was measured, and the average value of the detergency was taken as the detergency.
The reflectance before cleaning and the reflectance after cleaning were measured for various contaminated cloths with a reflectance meter (manufactured by Nippon Denshoku Co., Ltd., SE-2000), and the calculation was performed by the following formula to obtain the reflectance.
Cleaning rate (%) = (Reflectance after cleaning-Reflectance before cleaning) / (Reflectance of white cloth-Reflectance before cleaning) x 100
The results of blood washing on the blood-contaminated cloth are shown in Table 1 below. In the blood washing result column, A indicates that the blood washing power was 90% or more and 100% or less, B indicates that the blood washing power was 80% or more and less than 90%, and C indicates that the blood washing power was 80% or more and less than 90%. It indicates that the blood detergency was 70% or more and less than 80%, and D indicates that the blood detergency was less than 70%.

(Comparative Example 1)
In Comparative Example 1, a composition of 20% by mass of sodium sulfite, 5% by mass of malic acid and 75% by mass of water was supplied to the eleventh washing tub (the first tub of the rinsing step) as the neutralizing composition. Then, the blood-contaminated cloth was washed in the same manner as in Example 1. The hydrogen peroxide concentration in the rinsing water of the eleventh washing tub was 170 mass ppm. The cleaning results of the blood-contaminated cloth are shown in Table 1 below.

(Comparative Example 2)
In Comparative Example 2, as a neutralizing composition, a composition of 20% by mass of sodium sulfite, 5% by mass of malic acid and 75% by mass of water was supplied to the fourth washing tub (the first tub of the main washing step). Except for this, the blood-contaminated cloth was washed in the same manner as in Example 1. The hydrogen peroxide concentration in the washing water of the fourth washing tub was 350 mass ppm. The results of blood washing on the blood-contaminated cloth are shown in Table 1 below.

(Comparative Example 3)
In Comparative Example 3, a composition of 20% by mass of sodium sulfite, 5% by mass of malic acid and 75% by mass of water was supplied to the first washing tub (the first tub of the prewashing step) as the neutralizing composition. Then, the blood-contaminated cloth was washed in the same manner as in Example 1. The hydrogen peroxide concentration in the washing water of the first washing tub was 0 mass ppm. However, the hydrogen peroxide concentration in the water to be washed was 30 mass ppm. The results of blood washing on the blood-contaminated cloth are shown in Table 1 below.

(Comparative Example 4)
In Comparative Example 4, a composition of 20% by mass of sodium sulfite, 5% by mass of malic acid and 75% by mass of water was supplied to the water input tank to be washed as a neutralizing composition as a hydrogen peroxide reducing agent. Washed the blood-contaminated cloth in the same manner as in Example 1. The hydrogen peroxide concentration in the input water of the water input tank for the object to be washed was 0 to 10 mass ppm, which was non-uniform. The results of blood washing on the blood-contaminated cloth are shown in Table 1 below.

(Comparative Example 5)
In Comparative Example 5, a composition of 20% by mass of sodium sulfite, 5% by mass of malic acid and 75% by mass of water was used as a neutralizing composition as a hydrogen peroxide reducing agent in a water input tank for washing and a water recycling tank for dehydrated recovery water. The blood-contaminated cloth was washed in the same manner as in Example 1 except that the water was supplied to the connecting pipe (corresponding to the supply pipe 701 in FIG. 2). The hydrogen peroxide concentration in the pipe connected to the water input tank for the object to be washed was 0 to 15 mass ppm, which was non-uniform. The results of blood washing on the blood-contaminated cloth are shown in Table 1 below.

From the results in Table 1, it was found that an excellent blood cleaning effect was obtained by supplying the hydrogen peroxide reducing agent to the 16th washing tub (finishing tub). This result shows that the reducing effect of the hydrogen peroxide reducing agent on hydrogen peroxide is remarkably exhibited in the finishing process performed in the finishing tank.

(Experimental Examples 1 to 5)
In Experimental Examples 1 to 5, the blood-contaminated cloth was washed using the same continuous washing machine as in Example 1. The difference between Experimental Examples 1 to 5 and Example 1 is that the temperature of the input water and the hydrogen peroxide concentration in the input water are set to predetermined values. The temperature of the input water in the water input tank for the object to be washed was set by adjusting the temperature of the water in the finishing tank using a heat exchanger (not shown in FIG. 2). Further, the hydrogen peroxide concentration of the input water was adjusted by adjusting the input amounts of the compositions of 20% by mass of sodium sulfite, 5% by mass of malic acid and 75% by mass of water to be put into the finishing tank.
The results of blood washing on the blood-contaminated cloth are shown in Table 2 below. In the column of residual rate of reducing power, A indicates that the blood cleaning power was 80% or more and 100% or less, B indicates that the blood cleaning power was 70% or more and less than 80%, and C. Indicates that the blood detergency was less than 70%.

From the results in Table 2, it was found that an excellent blood washing effect was obtained when the concentration of hydrogen peroxide in the input water was 0 mass ppm or more and 10 mass ppm or less. Further, even if the temperature of the input water is 46 ° C. or higher (that is, an environment that promotes the oxidation of blood stains in the object to be washed), the hydrogen peroxide concentration in the input water is adjusted to 0 mass ppm or more and 2 mass ppm or less. As a result, it was found that an excellent blood cleaning effect was obtained. The higher the temperature of the input water, the more excellent the dehydration effect on the object to be washed can be obtained.

(Experimental Examples 6 to 15)
In Experimental Examples 6 to 15, a neutralizing composition containing a hydrogen peroxide reducing agent, a sour agent, and water was prepared. After allowing the obtained neutralizing composition to stand for 24 hours under open conditions, the residual rate of the reducing power of the neutralizing composition was measured by comparing with a single hydrogen peroxide reducing agent. The method for measuring the residual rate of reducing power was as follows. First, 100 g of an aqueous solution of 350 mass ppm hydrogen peroxide, 0.125 M sulfuric acid, and 0.5 mass% potassium iodide, which was colored reddish brown, was neutralized with a single hydrogen peroxide reducing agent or after standing for 24 hours. Titration was performed with the composition, and the end point was when the color of the aqueous solution disappeared.
Next, the residual ratio of the reducing power was set to (total titration mass up to the end point when titrated with a single hydrogen peroxide reducing agent having the same mass% as that of the hydrogen peroxide reducing agent in the neutralizing composition) / (static for 24 hours). The total titration mass up to the end point when titrated with the neutralized composition after placement) × 100 (%) was calculated.
Further, the neutralizing composition was supplied to the 16th washing tub (finishing tub) in the continuous washing machine used in Example 1. Then, the object to be washed taken out from the 16th washing tub was dehydrated in the dehydration step, and the pH of the recovered water was measured. The residual condition of the alkaline component in the object to be washed was evaluated. Sodium sulfite was used as the hydrogen peroxide reducing agent. In addition, malic acid was used as a sour agent.
In addition, the following experiments were conducted as a method for determining the liquid stability of the neutralizing composition at low temperatures. Specifically, the obtained neutralization composition was placed in a 100 ml vial, and the temperature was adjusted to each temperature (15 ° C., 5 ° C., −5 ° C.). 20 mg of sodium sulfite powder was added to the sample adjusted to each temperature, and the mixture was stirred for 1 minute and then allowed to stand for 1 day. At each temperature, the solubility of the sodium sulfite powder post-added to the neutralization composition was evaluated.
Table 3 below shows each mass part of sodium sulfite, malic acid, and water, the residual rate of reducing power, the residual state of the alkaline component in the object to be washed, and the state of liquid stability at low temperature.
In the column of the residual rate of reducing power, A indicates that the residual rate of reducing power was 80% to 100%, and B indicates that the residual rate of reducing power was less than 80%.
In the column of the residual state of the alkaline component in the object to be washed, A indicates that the pH of the water recovered in the dehydration step was less than 9, and B indicates that the pH of the water recovered in the dehydration step was 9 or more. Indicates that it was.
In the column of each temperature, those in which the precipitation increased after 1 day were marked with x, those in which there was no change were marked with Δ, and those in which the precipitation disappeared were marked with ◯.

From the results in Table 3, the mass ratio of sodium sulfite to malic acid in the neutralization composition was 1.5 or more and 8.0 or less, preferably 1.5 or more and 3.5 or less, and more preferably 1.5 or more and 2.5. When it was the following, it was found that the neutralizing composition was excellent in the residual rate of reducing power. It was also found that the residual state of the alkaline component in the object to be washed was also good.

(Experimental Examples 16 to 20)
In Experimental Examples 16 to 20, a neutralizing composition containing a hydrogen peroxide reducing agent, a sour agent, and water was prepared. The obtained neutralizing composition was stored in a vial and allowed to stand for 24 hours under open conditions, and then the residual rate of the reducing power of the neutralizing composition was measured. Sodium sulfite was used as the hydrogen peroxide reducing agent. In addition, malic acid was used as a sour agent.
Table 4 below shows each mass part of sodium sulfite, malic acid, and water, and the residual rate of reducing power. In the column of the residual rate of reducing power, A indicates that the residual rate of reducing power was 90% to 100%, and B indicates that the residual rate of reducing power was less than 90%.

From the results in Table 4, it was found that when sodium sulfite was diluted to 6.0 parts by mass or less, the reducing power was reduced to less than 90% after 24 hours due to the influence of oxidation by air. It was suggested that the blending ratio of water in the neutralization composition is preferably 80 parts by mass or less.

1 to 12 1st washing tub to 12th washing tub 13 Dehydrator 14 Washing object input port 100 Washing body 101, 102, 103, 109, 112, 113 Drain pipe 120 Drive device 130 Central axis 200 Detergent dilution and dissolution tank 300 Bleaching agent Diluting tank 400 Neutralizing composition tank 500 Finishing agent tank 600 Reclaimed water tanks 601, 602, 701, 801 Supply pipe 610 Reclaimed water transfer pump 620 Reclaimed water transfer pump 700 Dewatering reclaimed water recycling tank 710 Dewatering reclaimed water transfer pump 800 Washing material input water tank 810 Water input water transfer pump W1, W2, W3 Water E1, E2, E3 Drainage

Claims (7)

Equipped with a pre-washing unit, a main-washing unit, a rinsing unit, and a finishing unit,
The pre-washing unit includes a plurality of washing tubs, and a drain pipe is connected to the washing tub of the pre-washing unit.
The main washing unit includes a plurality of washing tubs and has a plurality of washing tubs.
The rinsing unit includes a plurality of washing tubs, and a drain pipe is connected to the most upstream washing tub of the rinsing units.
The inclined barrier between the most downstream washing tub of the main washing unit and the most upstream washing tub of the rinsing unit is formed higher than other inclined barriers.
A washing method using a continuous washing machine provided with a recycling tank into which drainage discharged from the rinsing unit flows in, and the recycling tank and the most downstream washing tub of the main washing unit are connected by a supply pipe. hand,
The first washing step of washing the object to be washed with the first washing water containing the first alkaline detergent, and
A second cleaning step of cleaning the object to be washed, which has undergone the first cleaning step, with a second washing water containing a second alkaline detergent and hydrogen peroxide.
A rinsing step of rinsing the object to be washed that has undergone the second washing step with rinsing water,
It has a finishing step of treating the object to be washed, which has undergone the rinsing step, with finishing water containing a neutralizing composition containing a sour agent and a hydrogen peroxide reducing agent.
Using the input water containing wastewater in the finishing step, the object to be washed is charged into the first cleaning water in the first cleaning step .
Supplying fresh water (W1) to the final tub of the rinsing unit so as to flow toward the upstream washing tub.
To supply fresh water (W2) to the finishing unit,
The sour agent is at least one selected from the group consisting of malic acid and citric acid.
The hydrogen peroxide reducing agent is sodium sulfite,
The mass ratio represented by [hydrogen peroxide reducing agent] / [sour agent] is 1.5 or more and 2.5 or less.
A washing method in which the content ratio of the hydrogen peroxide reducing agent in the neutralization composition is 10% by mass or more and 30% by mass or less. The washing method according to claim 1, wherein the pH of the finishing water in the finishing step is 6.0 or more and 9.0 or less. The washing method according to claim 1 or 2, wherein the neutralizing composition is a one-component type. The washing method according to any one of claims 1 to 3, wherein the concentration of the hydrogen peroxide in the input water is 0 mass ppm or more and 10 mass ppm or less. The washing method according to any one of claims 1 to 4, wherein the concentration of hydrogen peroxide in the first washing water is 0 mass ppm or more and 10 mass ppm or less. Contains sour agent and hydrogen peroxide reducing agent,
A neutralizing composition used in the finishing step in the washing method according to any one of claims 1 to 5. Contains more water,
pH is Ru der 4.0 to 10.0, neutralization composition of claim 6.

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