KR20020023632A - A method of producing a wash, and a wash itself - Google Patents

Abstract

PURPOSE: A method of preparing a washing water compatible with safety and washing quality is provided, by which it is possible to obtain a higher rust preventive effect than alkaline water prepared by conventional electrolysis. CONSTITUTION: In the method of preparing washing water, a process by which sulfate ions in raw water are made to be lower than 0.2 mmol/dm¬3 and/or chloride ions lower than 0.5 mmol/dm¬3, calcium ions lower than 1.0 mmol/dm¬3, and Mg ions lower than 1.0 mmol/dm¬3, is performed and subsequently a process by which sodium carbonate concentration in raw water is made to be 0.1-10.0 mmol/dm¬3, is performed, and then this water is electrolyzed to obtain washing water having the pH range of 8.0 to 13.0 and/or the oxidation reduction potential range of -100 mV to -1,000 mV.

Description

A method of producing a wash, and a wash itself}

The present invention relates to a process for producing alkaline washing water obtained by electrolysis of water.

In degreasing washing, a large amount of halogenated hydrocarbon-based cleaning liquids represented by flolon 113 or 1 · 1 · 1-trichloroethane can be used in large quantities, such as ozone layer destruction, groundwater or Environmental destruction such as soil pollution has been pointed out, and most substances are banned. Technical development of alternative cleaning methods has been made in place of these, and various cleaning methods have been proposed, but each includes a problem.

Alternative cleaning methods are broadly divided into water-based, semi-aqueous and non-aqueous.

The aqueous system is a method of using an alkaline detergent or a neutral detergent, there is a method of washing only with clear or pure water. By the way, when cleaning metals, especially steel, in any water-based cleaning method, the generation of rust often becomes a problem, and a large amount of thermal energy is required in the drying process, or a rust inhibitor must be used together.

In particular, the method using the detergent requires a rinsing process or the concentration control of the detergent. In addition, there is a reported risk that the surfactant contained in the detergent contains a component (alkylphenol, nonylphenol, etc.) suspected of endocrine disrupting action.

In addition, the cleaning with only pure water or pure water may not obtain a sufficient cleaning effect.

The compliant system uses a cleaning solution in which glycol ether, alcohol, ester or the like is mixed with water, but there is a risk of ignition. In addition, the need for a rinsing step or consideration of rust prevention is similar to that of an aqueous system.

Since non-aqueous systems use flammable solvents such as alcohols and hydrocarbons, explosion-proof measures are required. In addition, some solvents are slow to dry, and it is necessary to enlarge the drying equipment.

In the meantime, the technique which uses alkaline water obtained by electrolyzing water as washing water as published in Unexamined-Japanese-Patent No. 10-192860 is attracting attention.

This method improves the washing power of water by using general clear water, industrial water and the like as alkaline water which is electrolyzed as a raw material without using a surfactant or an alkali chemical agent.

Since the cleaning power is increased without impairing the safety of water, it is effective as an alternative cleaning.

In addition, alkaline ionized water has an effect of suppressing the occurrence of rust compared with other water cleaning methods. However, this does not have a long-term effect on all metals, and as long as it is a water rinse, the need for rust protection is the same as for other water washes.

Japanese Laid-Open Patent Publication No. Hei 9-137287 discloses a method of washing with alkaline water after washing with acidic ionized water when alkaline water obtained by electrolysis is used for washing iron processed products.

However, since acidic ionized water is corrosive to metals, there is a problem that rust occurs in a step of cleaning with acidic ionized water in steel or cast iron products in which iron is exposed without surface treatment such as plating.

In addition, when electrolytic water or industrial water is electrolyzed, calcium ions and magnesium ions contained therein move toward alkaline water by electrolysis, and their ion concentration is high. Some of these ions are carbonate compounds, which precipitate together with silica in water and adhere to pipes and valves, and therefore, the inside of the electrolytic ion water production apparatus needs to be regularly cleaned with an acid solution or the like.

Moreover, in electrolysis, alkaline water is generated at the cathode side, and almost the same amount of acidic water is produced at the anode side. Since the acidic water is corrosive to metal as described above, it is inadequate for washing and is usually drained. Since the pH is about 2.5 to 5.5, it has to be neutralized and drained with alkaline chemicals.

On the other hand, when aluminum is washed with alkaline water, when the cleaning temperature is high and the time to be cleaned is in contact with the washing water for a long time, the surface of the aluminum may be discolored to black brown, which may not be suitable for cleaning aluminum.

An object of the present invention is to provide a washing water which can obtain a higher rust-preventing effect than alkaline water by conventional electrolysis, and which can achieve both safety and cleaning quality.

In order to achieve the above object, the present invention according to claim 1 comprises the steps of: calcium ion concentration in raw water of 1.0 mmol / dm ³ or less, magnesium ion concentration of 1.0 mmol / dm ³ or less; Adjusting the sodium carbonate concentration to 0.1 to 10.0 mmol / dm ³ and electrolyzing it to obtain washing water having a pH value in the range of 8.0 to 13.0 or a redox potential of -100 mV to -1000 mV. It is a manufacturing method of washing water.

The present invention according to claim 2, the sulfuric acid ion in the raw water to 0.2mmol / dm ³ or less, chloride ion to 0.5mmol / dm ³ or less, calcium ion concentration to 1.0mmol / dm ³ or less, magnesium ion concentration 1.0mmol / dm ³ and a step of less than, then with a step of adjusting the sodium carbonate concentration in the raw water by 0.1 ~ 10.0mmol / dm ^3, or this, the range of the pH value is 8.0 to 13.0 by the electrolysis, oxidation-reduction potential is It is a manufacturing method of the washing water characterized by obtaining the washing water of -100mV--1000mV.

The present invention according to claim 3, wherein in the method for preparing the washing water described above, the preparation of the washing water comprising the step of adding calcium hydroxide to the prepared washing water in the range of 0.05 mmol / dm ³ to 2 mmol / dm ³ . Way.

The present invention according to claim 4 is a washing water, which is prepared by the method for producing washing water described above, wherein the dissolved hydrogen concentration in alkaline water is 0.01 mg / dm ³ or more and the dissolved oxygen concentration is 6 mg / dm ³ or less. .

Hereinafter, the present invention will be described in more detail.

(Invention of Claim 1) When alkaline water is produced by electrolysis and used as washing water, white scales precipitate in the electrolytic cell or inside the pipe to block the flow path, which reduces the production rate of alkaline water or damages the electrolytic cell. You can. This is because calcium ions or magnesium ions contained in the raw water move toward alkaline water by electrolysis, resulting in high concentrations of calcium and magnesium ions in alkaline water, and these ions precipitate together with silica in water as a carbonate compound. When the calcium ion concentration is 2.0mmol / dm ³ , when electrolysis is performed for 60 to 80 hours, the scale begins to adhere to the pipe. At 100 hours, the pipe of 10 mm inner diameter is blocked.

Therefore, in the present invention to prevent the adhesion of scale found that the calcium ion concentration in the raw water before the electrolysis to less than 1.0mmol / dm ^3, and that to the magnesium ion concentration to less than 1.0 mmol / dm ³ Effective It was. By doing in this way, generation | occurence | production of the compound which a calcium carbonate, magnesium carbonate, etc. tend to become scale in an electrolytic cell or piping can be prevented.

This effect is remarkable when the sum of the calcium ion concentration and the magnesium ion concentration in the raw water is 1.5 mmol / dm ³ or less, and the cation concentration is 1.0 mmol / dm ³ or less, respectively. Does not occur.

In addition, acidic water generated at the same time as alkaline water is drained because rust is generated when the metal is used to clean the metal. If pH is low, it is neutralized and drained.

However, the Applicant adds sodium carbonate to the raw water, adjusts its concentration to 0.1 to 10.0 mmol / dm ³ and then electrolyzes, so that the pH of the generated acidic water is in the range of 5.8 to 6.5, neutralizing for drainage. Found no need.

In particular, by setting the calcium and magnesium ions concentrations in the raw water to 1.0 mmol / dm ³ or less, respectively, it is possible to prevent precipitation of the added sodium carbonate into the carbonate, thereby obtaining an effect by adding a small amount of sodium carbonate.

In this way, it is possible to electrolyze raw water adjusted with ionic components to obtain a wash water having a pH value of 8.0 or more and 13.0 or less, or a redox potential of -100 mV to 1000 mV, as compared with the conventional method. However, the drainage treatment has the advantage that the effort can be greatly reduced.

However, when the sodium carbonate concentration is 10.0 mmol / dm ³ or more, the residual ion component of the cleaning product increases, which is not suitable for fine cleaning.

(Invention of Claim 2) Furthermore, when the sulfate ion and the chloride ion were reduced before or after the process of reducing calcium ion and magnesium ion in raw water, it was found that the metal corrosion of the obtained alkaline water is greatly reduced.

In particular, the steel sheet was prepared in alkaline water obtained by electrolyzing raw water containing 0.2 mmol / dm ³ or less of sulfate ions or 0.5 mmol / dm ³ or less of chloride ions, and alkaline water produced without reducing sulfate and chloride ions. When immersion was performed and the time until rust was generated, rust was not generated longer than 3 times in the side where ion was reduced. In the case of aluminum immersion, surface discoloration was not observed in alkaline water in which sulfate ions or chloride ions were reduced, but the surface was discolored to black brown on the side where sulfate ions and chloride ions were not reduced.

Sulfate ions and chloride ions present in raw water are concentrated on the acidic side by electrolysis, some remain in alkaline water. Since sulfate ions and chloride ions contained in these alkaline waters tend to accelerate their corrosion when forming local cells on the metal surface, rust is easily generated when they are present.

For this reason, if the sulfate ion or chloride ion contained in raw water is reduced beforehand, there exists an effect of improving the rust prevention property of the generated alkaline water.

(Invention of Claim 3) Moreover, when calcium hydroxide is added to the said alkaline water in the range of 0.05 mmol / dm <^3> -2mmol / dm <^3> , the rust resistance of alkaline water can be improved further.

This is because calcium ions of the added calcium hydroxide combine with hydrogen carbonate in alkaline water to form calcium hydrogen carbonate (Ca (HCO ₃ )), and they exhibit a cathode inhibitor action, insoluble coating on the negative portion of the metal surface. It is thought that rust prevention effect occurs because it reduces the area where cathodic reaction occurs while generating.

Furthermore, in the case of adding sodium carbonate in the invention of claim 1, since the carbonate ions contained therein are in equilibrium with the hydrogen carbonate in water, it is helpful for the formation of the calcium hydrogen carbonate.

If the amount of added calcium hydroxide is less than 0.05 mmol, the formation of calcium hydrogen carbonate will be insufficient and the rust preventing effect will not be obtained. If it is 2 mmol / dm ³ or more, calcium carbonate will float in the washing water as a precipitate. These will contaminate the object to be cleaned.

(Invention of claim 4) In a cathode in which alkaline water is produced in an electrolytic cell, hydrogen gas is generated when hydrogen overvoltage is exceeded at the electrode surface. When hydrogen gas is generated, the partial pressure of hydrogen in the cathode chamber increases, and the partial pressure of oxygen decreases relatively. The dissolved oxygen concentration is then lowered by Henry's law.

Dissolved oxygen has a strong effect of oxidizing the metal surface, especially in the range of 0 to 15 mg / dm ³ corrosion rate increases in proportion to the concentration.

That is, it is possible to improve the rust resistance of alkaline water by lowering the dissolved oxygen concentration with respect to hydrogen generation in the cathode, and according to the present invention, the rust prevention effect of alkaline water having a dissolved hydrogen concentration of 0.01 mg / dm ³ or less is remarkable. Found to be high.

A first embodiment of the present invention is described below.

The alkaline water of Example 1 used here was produced as follows.

Using tap water (tap water from Biwa-cho, Higashi-zai-gun, Shigaken, Japan, hardness 60ppm), and use this softening device (model name ME-5S manufactured by Nippon Water Co., Ltd.), ion exchange resin used: The calcium ion concentration and the magnesium ion concentration were made 0.005 mmol / dm ³ or less by passing through the strong acid cation exchange resin (sodium type). Sodium carbonate was added thereto to have a sodium carbonate concentration of 2.0 mmol / dm ³ .

The water was electrolyzed in an electrolytic cell equipped with a diaphragm to obtain alkaline water, which was used as washing water. The conditions of electrolysis were DC 60V, a current density of 1.0 A / dm ² , and a production amount of 2 L / min.

The alkaline water of the second embodiment uses tap water as tap water (tap water from Biwa-cho, Higashi-Azai-gun, Japan, hardness 60ppm), which is manufactured by Ion-Exchange Resin-type pure water device (Japan Soft Water Co., Ltd.). The calcium ion concentration, the magnesium ion concentration, the sulfate ion concentration, and the chlorine ion concentration were adjusted to 0.005 mmol / dm ³ or less in total. Sodium carbonate was added thereto to have a sodium carbonate concentration of 2.0 mmol / dm ³ . This was electrolyzed under the same conditions as in the first embodiment to obtain alkaline water, which was used as washing water.

In the alkaline water of Example 3-1, 1.0 mmol / dm ³ of calcium hydroxide was added to the alkaline water obtained in Example 1 to obtain washing water.

In the alkaline water of Example 3-2, 1.0 mmol / dm ³ of calcium hydroxide was added to the alkaline water obtained in Example 2 to obtain washing water.

In addition, alkaline water of Comparative Examples 1, 2-1, 2-2, 2-3, 3-1, 3-2, 3-3, 3-4 was produced for comparison.

The alkaline water of Comparative Example 1 omits the step of passing the water softener in the first embodiment and is electrolyzed without adjusting the calcium ion concentration and the magnesium ion concentration in the raw water.

The alkaline water of Comparative Example 2-1 was electrolyzed by changing the addition of sodium carbonate to the first example by adding sodium chloride. The amount of sodium chloride added was such that the concentration of sodium chloride in the raw water was 4.0 mmol / dm ³ . This is for the sodium ion concentration to be the same as in the case of sodium carbonate.

The alkaline water of Comparative Example 2-2 was electrolyzed at a concentration of 0.05 mmol / dm ³ of sodium carbonate in Example 1 to obtain alkaline water, which was used as washing water.

The alkaline water of Comparative Example 2-3 was electrolyzed at a concentration of 15.0 mmol / dm ³ of sodium carbonate in Example 1 to obtain alkaline water, which was used as washing water.

In the alkaline water of Comparative Example 3-1, 0.03 mmol / dm ³ of calcium hydroxide was added to the alkaline water obtained in Example 1 to obtain washing water.

In the alkaline water of Comparative Example 3-2, 3.0 mmol / dm ³ of calcium hydroxide was added to the alkaline water obtained in Example 1 to obtain washing water.

In the alkaline water of Comparative Example 3-3, 0.03 mmol / dm ³ of calcium hydroxide was added to the alkaline water obtained in Example 2 to obtain washing water.

In the alkaline water of Comparative Example 3-4, 3.0 mmol / dm ³ of calcium hydroxide was added to the alkaline water obtained in Example 2 to obtain washing water.

The alkaline water was used as the washing water, and the washing performance, the rust preventing property, the anti-stick adhesion, and the pH of the acidic water were compared by the method described below.

As the object to be cleaned, a general cold rolled steel sheet (SPCC) having a size of 100 × 50 × t1 mm was used. The press processing machine (PG-3066 from Japan Machine Tools Co., Ltd.) was applied, and each washing water was sprayed and sprayed to clean, dried with warm air, and left to dry after being completely dried. The cleaning conditions were set at 60 ° C. for a washing water temperature of 0.5 MPa, a washing time of 2 minutes, and a washing water amount of 15 L / min.

The evaluation method was judged by immersing the water to be washed in hot water dried after washing for 1 minute in a 25% ink solution, and then lifting and drying naturally.

In addition, the rust preventive property was judged by observing the occurrence of rust by leaving the object to be washed in the indoors not immersed in the ink solution.

In evaluating the adhesion of the alkaline water to the piping of the alkaline water in the electrolytic ion water generator, it was judged by observing the scale attached to the inner surface of the piping hose.

In addition, the pH of the acidic water generated at the same time as the alkaline water was also measured to determine drainage.

Table 1 shows the pH and evaluation results of each alkaline water.

PH of alkaline water Washing water Antirust Prevent adhesion of scale PH of acidic water First embodiment 10.5 ○ ○ ○ ○ Second embodiment 10.6 ○ ◎ ○ ○ Example 3-1 10.9 ○ ◎ ○ ○ Example 3-2 10.9 ○ ◎ ○ ○ Comparative Example 1 10.6 ○ ○ × ○ Comparative Example 2-1 10.6 ○ △ ○ × Comparative Example 2-2 9.7 △ ○ ○ △ Comparative Example 2-3 10.6 ○ ○ ○ ○ Comparative Example 3-1 10.7 ○ ○ ○ ○ Comparative Example 3-2 10.9 ○ ◎ △ ○ Comparative Example 3-3 10.8 ○ ○ ○ ○ Comparative Example 3-4 10.9 ○ ◎ △ ○

In Table 1, the cleansability ○ indicates 100% of wet ink and Δ indicates 85% or more. ◎ of antirust is left for 60 days, and no rust occurs. ○ indicates left rust for 60 days, and △ stands for 40 days.

때 is not attached to the pipe even after 300 hours of electrolysis, △ is not attached to the pipe, but is attached to the cleaning tank, and 는 is attached to the pipe in 60 hours. Indicates. The pH of the acidic water indicates that the pH is between 5.8 and 6.5, Δ indicates that the pH is between 4.5 and 5.8, and × indicates that the pH is below 4.4.

From the above results, it can be seen that the Examples 1, 2, 3-1, and 3-2 are excellent in all the items of the cleaning property, the rust resistance, the anti-scaling adhesion, and the pH of the acidic water.

Moreover, the washing method using the washing water described in each claim of the present invention is not limited to the above-described materials and methods, and is effective also for the to-be-cleaned objects other than steel, and the washing method is also used for immersion stirring, immersion ultrasonic cleaning, and the like. Excellent effect.

Next, a second embodiment of the present invention will be described below.

Alkaline water used in this example was prepared under the same production conditions as in the first example.

As Comparative Example 4, in order to reduce the dissolved hydrogen concentration, alkaline water obtained by lowering the electrolytic voltage to 5 V DC and electrolyzing was used as washing water. However, the addition amount of sodium carbonate was 10.0 mmol / dm ³ so that pH might not fall.

About evaluation, it implemented about washability and rust prevention property. Evaluation methods and symbols of the table are the same as in the first embodiment.

Table 2 shows the pH and evaluation results of each alkaline water.

PH of alkaline water Dissolved Hydrogen Concentration (mg / dm ³ ) Dissolved Oxygen Concentration (mg / dm ³ ) Detergency Antirust First embodiment 10.5 0.052 3.0 ○ ○ Comparative Example 4 10.6 0.002 8.2 ○ △

From the above results, it can be seen that the higher the dissolved hydrogen concentration and the lower the dissolved oxygen concentration, the higher the rust prevention effect.

As described above, according to the present invention, since sulfate ion concentration, chloride ion concentration and dissolved oxygen concentration are low, alkaline water having high rust resistance can be obtained. In addition, by lowering the calcium ion concentration and the magnesium ion concentration, it is possible to obtain alkaline water having anti-stick adhesion in the piping.

Moreover, since the pH of the acidic water does not become lower than 5.8, it becomes drainable without neutralization.

Claims (4)

Adjusting the calcium ion concentration in the raw water to 1.0 mmol / dm ³ or less, the magnesium ion concentration to 1.0 mmol / dm ³ or less, and thereafter adjusting the sodium carbonate concentration in the raw water to 0.1 to 10.0 mmol / dm ³ . Including, Electrolyzing this to obtain a washing water, pH value is in the range of 8.0 to 13.0, or the redox potential is -100mV ~ -1000mV to obtain a washing water. The process of reducing the sulfate ion in raw water to 0.2 mmol / dm ³ or less, the chloride ion to 0.5 mmol / dm ³ or less, the calcium ion concentration to 1.0 mmol / dm ³ or less, and the magnesium ion concentration to 1.0 mmol / dm ³ or less; And then adjusting the sodium carbonate concentration in the raw water to 0.1-10.0 mmol / dm ³ , Electrolyzing this to obtain a washing water, pH value is in the range of 8.0 to 13.0, or the redox potential is -100mV ~ -1000mV to obtain a washing water. The method according to claim 1 or 2, further comprising adding calcium hydroxide to the prepared washing water in the range of 0.05 mmol / dm ³ to 2 mmol / dm ³ . A washing water prepared by the method according to any one of claims 1 to 3, wherein the dissolved hydrogen concentration in alkaline water is 0.01 mg / dm ³ or more and the dissolved oxygen concentration is 6 mg / dm ³ or less. .