Method for cleaning material surfaces and hydrogen generator

Abstract

This invention provides a method for cleaning the surfaces of materials such as metals, resins, and glass using a hydrogen-based cleaning machine, and a hydrogen generator used therefor. [Solution] The hydrogen generator 1 is used for cleaning material surfaces that undergo a water-based cleaning process and comprises a main unit 2 that generates hydrogen, a cleaning machine 3 containing pure water in a tank, and a hydrogen supply passage 4 that supplies hydrogen from the main unit 2 to the cleaning machine 3. This allows the hydrogen generated by the main unit 2 to be supplied in real time to the pure water in the cleaning machine 3 via the hydrogen supply passage 4.

Description

Technical Field

[0001] The present invention relates to a method for cleaning the surface of a material through a water washing process and a hydrogen generator used therefor.

Background Art

[0002] Before processing the surface of a material by painting, vapor deposition, plating, etc., it is necessary to carefully clean the surface so that the light transmittance becomes high. For this purpose, it is usually common to use an organic solvent or an alkaline cleaning agent as a cleaning agent (see, for example, Patent Document 1 and Patent Document 2).

[0003] However, depending on the material, it may be attacked by the cleaning agent, and although the surface becomes clean, it may dissolve, crack, etc., resulting in a decrease in quality and becoming unsuitable as a product.

[0004] In addition, since various chemicals are used in cleaning, there are risks of environmental pollution and workers being exposed to chemical substances.

[0005] Here, in the conventional cleaning method, in cleaning using an organic solvent made from petroleum or coal as a raw material, it was impossible to cope with a high cleaning level, and moreover, it was easy to cause environmental pollution.

[0006] To prevent this, when a high cleaning level and environmental pollution are required, cleaning using an aqueous cleaning agent is performed. In that case, the general cleaning process is as follows in (1). Cleaning (aqueous cleaning agent) → tap water rinse → pure water rinse → drying ··· (1)

[0007] However, in this cleaning process of (1), since a water washing process is included, due to the high dissolving ability of pure water, the object to be cleaned is often affected by water as follows. · Metals: Rusting · Resins: Dissolving, cracking, discoloration · Glasses: Scratches, particles

[0008] In particular, optical glass used in optical instruments, such as soft glass, is delicate, especially high-performance glass with high light transmittance, and there is a concern that it is prone to developing scratches when washed with water. As a result, machine cleaning is not possible, and dirt must be removed by hand wiping by workers, which reduces mass production efficiency and increases costs. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2019-131450 [Patent Document 2] International Publication No. 2004 / 050266 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0010] Here, hydrogen gas is gaining popularity as an alternative to conventional energy sources. Hydrogen water, which is produced by dissolving hydrogen gas in water, exhibits a lower oxidation-reduction potential and reduced properties, as well as alkalinity. Therefore, if cleaning can be done using this hydrogen water, rusting of metals will be suppressed, and the outermost layer of resins and glass will be dissolved and removed, resulting in a clear surface with high light transmittance, which can be described as "peeling off a layer."

[0011] The present invention aims to provide a method for cleaning the surfaces of materials such as metals, resins, and glass using a hydrogen-based cleaning machine, and a hydrogen generator used therefor. [Means for solving the problem]

[0012] Based on the inventor's findings, the present invention provides the following means for solving the above-mentioned problems.

[0013] <1> A method for cleaning a material surface, comprising a water-based cleaning agent followed by a water-based cleaning step, characterized in that hydrogen is used during the water-based cleaning step.

[0014] <2> The aforementioned material is at least one of metals, resins, and glass. <1> This is a method for cleaning the surface of the material described in [reference].

[0015] <3> The aforementioned material is glass. <2> This is a method for cleaning the surface of the material described in [reference].

[0016] <4> The hydrogen supply rate to the water used is between 50 ml / min and 4,000 ml / min. <1> This is a method for cleaning the surface of the material described in [reference].

[0017] <5> The amount of hydrogen supplied to the water used is between 500 ml / min and 4,000 ml / min. <4> This is a method for cleaning the surface of the material described in [reference].

[0018] <6> When using hydrogen, the hydrogen generated by electrolysis is supplied to the water in real time. <5> This is a method for cleaning the surface of the material described in [reference].

[0019] <7> The aforementioned washing step with water is a step of rinsing with tap water followed by rinsing with pure water, and the hydrogen is used in this pure water rinsing step. <1> from <6> This is a method for cleaning the surface of a material as described in any of the following.

[0020] <8> The aforementioned washing step with water is performed after using a water-based cleaning agent. <1> from <6> This is a method for cleaning the surface of a material as described in any of the following.

[0021] <9> <1> from <8> A hydrogen cleaning apparatus used for cleaning materials as described in any of the above, characterized in that when hydrogen is used, it is equipped with a hydrogen supply path that supplies hydrogen generated by electrolysis to water in real time.

[0022] In the present invention, "municipal water" means ordinary tap water. Also, in the present invention, "pure water" means purified water from which impurities such as chlorine and calcium have been removed from tap water, and includes commercially available products that have been subjected to such treatment in advance.

Advantages of the Invention

[0023] In the method for cleaning the surface of the material of the present invention, since hydrogen is used during the cleaning step with water, the surface of the material can be cleaned with a cleaning machine using hydrogen.

[0024] The hydrogen generator of the present invention is used in the method for cleaning the surface of the material of the present invention and includes a hydrogen supply path that supplies hydrogen generated by electrolysis to water in real time, so that the surface of the material can be cleaned with a cleaning machine using hydrogen.

Brief Description of the Drawings

[0025] [Figure 1] Figure 1 is a schematic diagram showing the hydrogen supply method in the present invention. [Figure 2] Figure 2 is a graph showing the change in water quality when hydrogen gas is dissolved in pure water in the present invention. [Figure 3] Figure 3 is a graph showing the optimal cleaning conditions for the main metals in the present invention. [Figure 4] Figure 4 is a graph showing the optimal cleaning conditions for the main resins in the present invention. [Figure 5] Figure 5 is a graph showing the optimal cleaning conditions for the soft nitriding material in the present invention.

Embodiments for Carrying Out the Invention

[0026] Embodiments of the present invention will be described while referring to the drawings. Figure 1 is a schematic diagram showing the hydrogen supply method in the present invention. The method for cleaning the surface of the material of the present invention is a method for cleaning the surface of the material through a cleaning step with water. For example, hydrogen generated in real time is supplied by the hydrogen generator 1 shown in Figure 1 to clean the surface of the material.

[0027] While this water-based cleaning step is generally performed after using a water-based cleaning agent, it is not limited to this, and the water-based cleaning step may be performed from the beginning without using a water-based cleaning agent. Furthermore, in the water-based cleaning step, while it is generally performed by rinsing with tap water followed by rinsing with pure water, it is not limited to this, and the cleaning method of the present invention may be used to clean with hydrogen water from the beginning.

[0028] Now, the hydrogen generator 1 shown in Figure 1 mainly consists of the main unit 2, the washing machine 3, and the hydrogen supply path 4.

[0029] The main unit 2 of the device is equipped with a power supply 5 and an electrolytic cell 6, and the electrolytic cell 6 is further separated into a cathode 8 and an anode 9 via an ion exchange membrane 7.

[0030] In this configuration, applying voltage from power supply 5 to cathode 8 and anode 9 decomposes water into oxygen and hydrogen.

[0031] Here, a hydrogen supply passage 4 is provided between the cathode 8 side of the electrolytic cell 6 and the cleaning machine 3, allowing hydrogen gas H2 (see arrow in the figure) generated at the cathode 8 to be supplied to the cleaning machine 3 in real time via the hydrogen supply passage 4.

[0032] On the other hand, the washing machine 3 is a device consisting of a tank for washing materials. The tank contains pure water, that is, purified water from which impurities such as chlorine and calcium have been removed, such as tap water. Once hydrogen gas supplied from the main unit 2 dissolves and hydrogen water is generated, the material to be washed is placed in the tank and washed.

[0033] Here, the material is a material that undergoes processing such as painting, vapor deposition, or plating, and examples include metals, resins, and glass.

[0034] Suitable metals include, for example, iron (Fe), aluminum (Al), and copper (Cu).

[0035] Suitable resins include, for example, acrylic resin, acrylonitrile butadiene styrene (ABS) resin, and polycarbonate (PC) resin. There are no particular restrictions on the type of glass used, but glass with high light transmittance and high functionality is preferred, and soft glass is particularly suitable as an example.

[0036] To clean these materials, hydrogen gas needs to dissolve in pure water to such an extent that its oxidation-reduction potential (ORP, measured in mV) drops to an alkaline state, i.e., above pH 7. In other words, while the pH of pure water is normally around 6, it needs to be increased to above 7, and to achieve this, the oxidation-reduction potential of the pure water must fall below 0 mV.

[0037] Here, the oxidation-reduction potential can be measured by inserting a platinum electrode and a reference electrode into the aqueous solution to be measured and reading the resulting potential difference; commercially available products for this purpose can be used as appropriate. Furthermore, pH can be measured using a pH meter, an electric device with a glass electrode inside, which generates a potential difference between a reference aqueous solution inside the glass electrode and the aqueous solution to be measured.

[0038] The amount of hydrogen generated by the main unit 2 supplied to the pure water in the washing machine 3 varies depending on the size of the washing machine 3's tank, but is between 50 ml / min and 4,000 ml / min. To obtain highly active hydrogen that can quickly change the quality of the pure water to alkaline, it is preferable that the supply rate is between 500 ml / min and 4,000 ml / min, and more preferably between 3,000 ml / min and 4,000 ml / min. If the hydrogen supply rate is less than 50 ml / min, the activity of the generated hydrogen decreases, making it impossible or extremely time-consuming to change the quality of the pure water to alkaline. On the other hand, it is physically impossible to obtain hydrogen at a rate exceeding 4,000 ml / min. Furthermore, by using a device that can supply the generated hydrogen to the washing machine 3 containing pure water in real time, as shown in the hydrogen generator 1 in Figure 1, the hydrogen supply rate can be adjusted, and it is possible to supply hydrogen at a rate of 500 ml / min or more. In addition, since the generated hydrogen can be supplied in real time, it is possible to supply hydrogen of high purity.

[0039] [Examples] (Verification of changes in the quality of pure water over time) The hydrogen generated by the hydrogen generator 1 shown in Figure 1 at a rate of 3,000 ml / min or more was supplied to the pure water of the washing machine 3 via the hydrogen supply path 4. The time-dependent changes in the oxidation-reduction potential (ORP, in mV) and pH of the pure water were measured. The results are shown in Figure 2. In the figure, the curved graph represents the oxidation-reduction potential, and the straight graph represents the time-dependent change in pH. The horizontal axis, "acceptable," refers to the time until the hydrogen water becomes suitable for washing, i.e., the acceptable hydrogen water (the same applies to Figures 3 and beyond).

[0040] As shown in Figure 2, the reducing properties of pure water increased to below 0mV in oxidation-reduction potential (ORP) approximately 30 minutes after the supply of hydrogen gas, i.e., the start of its dissolution. Furthermore, the pH reached 7 or higher approximately 50 minutes after the start of supply, making it suitable for washing. It was further possible to make it alkaline to above pH 8 approximately 70 minutes after the start of supply, and above pH 9 approximately 90 minutes after the start of supply.

[0041] (Verification of optimal cleaning conditions for major metals) As the target metals for cleaning, samples of iron (Fe), aluminum (Al), and copper (Cu) were washed with hydrogen water as shown in Figure 2, and the optimal pH conditions were verified. The results are shown in Figure 3. The graphs representing the oxidation-reduction potential and pH are the same as in Figure 2.

[0042] As shown in Figure 3, rust-free cleaning was possible for iron at a pH of approximately 7-9, and for aluminum and copper at a pH of approximately 8-9.

[0043] In other words, according to the present invention, it has been found that hydrogen water suitable for cleaning can be generated for any type of metal approximately 70 minutes after the start of hydrogen supply.

[0044] (Verification of optimal cleaning conditions for major resins) As the target resins for cleaning, samples of acrylic resin, ABS resin, and PC resin were washed with hydrogen water as shown in Figure 2, and the optimal pH conditions were verified. The results are shown in Figure 4. The graphs representing the oxidation-reduction potential and pH are the same as in Figure 2.

[0045] As shown in Figure 4, cleaning was possible without dissolution of areas other than the very surface, cracking, or discoloration at a pH of approximately 7-9 for acrylic resin, and at approximately 8-9 for ABS resin and PC resin.

[0046] In other words, according to the present invention, it has been found that hydrogen water suitable for cleaning can be generated in any type of resin approximately 70 minutes after the start of hydrogen supply.

[0047] (Verification of optimal cleaning conditions for soft glass materials) As the target glass materials for cleaning, samples of soft glass materials FPL51, FPL53, and FPL55 were washed with hydrogen water as shown in Figure 2, and the optimal pH conditions were verified. The results are shown in Figure 5. The graphs representing the oxidation-reduction potential and pH are the same as in Figure 2.

[0048] As shown in Figure 5, cleaning without generating latent scratches or particles was possible with FPL51 at a pH of approximately 7-9, and with FPL53 and FPL55 at a pH of approximately 8-9.

[0049] In other words, according to the present invention, it has been found that hydrogen water suitable for cleaning can be generated in any type of glass approximately 70 minutes after the start of hydrogen supply.

[0050] Here, soft glass materials with a higher FPL value have a higher refractive index, lower scattering rate, higher transparency, less refraction and scattering of light, and can provide sharper and clearer images. Therefore, in this invention, it has become clear that even highly transparent and high-performance glass materials can be cleaned on the surface within about 70 minutes from the start of hydrogen supply.

[0051] Although embodiments of the present invention have been described in detail above, the material surface cleaning method and hydrogen generating apparatus used therein of the present invention are not limited to the above embodiments and may include any technical ideas conceivable within that scope. [Industrial applicability]

[0052] The present invention can be widely used for cleaning material surfaces that undergo a water-based cleaning process. [Explanation of symbols]

[0053] 1. Hydrogen generator 2. Main unit of the device 3 Washing machine 4. Hydrogen supply routes 5 Power supply 6 Electrolytic cell 7 Ion exchange membrane 8. Cathode 9. Anode

Claims

1. A method for cleaning a material surface, comprising a water-based cleaning step, characterized in that hydrogen is used during the water-based cleaning step.

2. The method for cleaning the surface of a material according to claim 1, wherein the material is at least one of metals, resins, and glass.

3. The method for cleaning the surface of a material according to claim 2, wherein the material is glass.

4. The method for cleaning the surface of a material according to claim 1, wherein the amount of hydrogen supplied to the water used is 50 ml / min or more and 4,000 ml / min or less.

5. The method for cleaning the surface of a material according to claim 4, wherein the amount of hydrogen supplied to the water used is 500 ml / min or more and 4,000 ml / min or less.

6. The method for cleaning a material surface according to claim 5, wherein, when using hydrogen, hydrogen generated by electrolysis is supplied to water in real time.

7. The cleaning step using water is a step of rinsing with tap water followed by rinsing with pure water, and the method for cleaning the surface of a material according to any one of claims 1 to 6, wherein hydrogen is used in the step of rinsing with pure water.

8. The method for cleaning a material surface according to any one of claims 1 to 6, wherein the cleaning step with water is performed after using a water-based cleaning agent.

9. A hydrogen generator used for cleaning the surface of a material according to any one of claims 1 to 8, characterized in that it is equipped with a hydrogen supply path that supplies hydrogen generated by electrolysis to water in real time when hydrogen is used.

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