JP7082368B2 - Anticorrosion method and equipment for structures - Google Patents

Description

The present invention relates to anticorrosion methods and devices for structures exposed to the atmosphere.

Structures such as walls, stairs, pedestals, bridges, or tanks in industrial plants that are exposed to the atmosphere are often made of steel. Steel contains impurities such as carbon, and the surface of steel is an aggregate of innumerable micro batteries (having an anode and a cathode). When the surface of the steel comes into contact with moisture or rainwater in the atmosphere, cations (corrosive Fe ²⁺ ) move from the anode side to the cathode side via the moisture or rainwater in the atmosphere, and the cations become oxygen etc. on the cathode side. It reacts and rust is generated.

In order to prevent the occurrence of rust, an anticorrosion method is widely used in which a weather resistant paint is applied to a structure exposed to the atmosphere. However, when a part of the structure is exposed due to coating defects such as uneven coating, physical damage, deterioration of the paint, etc., the exposed part of the structure is corroded. For this reason, repairs and repainting are repeated regularly, especially in salt-damaged areas near the coast, in a short period of time.

In order to extend the period until repainting, heavy-duty anticorrosion coating consisting of undercoat, intermediate coat, and topcoat has become established as a general coating technique. However, heavy-duty anticorrosion coating not only complicates construction, but also causes a large cost increase.

In order to solve the above-mentioned problems of heavy-duty anticorrosion coating, galvanic anode method using zinc or the like or an external power source type electrocorrosion protection technique has been proposed. The galvanic anode method is used for underground structures and ships, but its use is limited due to the principle problem that the anode is consumed. Many proposals have been made for electrical anticorrosion technology using an external power supply method, but the water film formed on the painted surface is often uneven, and a uniform anticorrosion current is applied through the water film and overcorrosion protection is achieved. The problem is to control the amount of current that does not cause the problem, and there are many unsolved problems in terms of economy and convenience.

In the electric anticorrosion technology of the external power supply method, for the purpose of securing the above-mentioned anticorrosion current flow path, an insulating coating film is formed on the structure, a conductive coating film is formed on the insulating coating film, and the conductive coating film is formed. Disclosed is an anticorrosion method in which an anode is electrically connected to a conductive coating film, a topcoat film is formed on the conductive coating film, and a voltage is applied to the conductive coating film (see Patent Document 1).

According to the invention of Patent Document 1, since a DC voltage is applied to the conductive coating film, an anticorrosion current can flow between the conductive coating film and the structure in the direction opposite to the corrosion current, and the structure is corroded. Can be suppressed. Further, since the anticorrosion current is passed through the conductive coating film, the flow path of the anticorrosion current can be secured.

Japanese Unexamined Patent Publication No. 11-314309

However, the invention of Patent Document 1 has a problem that when a DC voltage is applied to the conductive coating film, the glossiness of the topcoat film of the conductive coating film is lowered and the topcoat film is deteriorated. .. When the topcoat film deteriorates, it adversely affects the conductive coating film underneath and the insulating coating film underneath.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly reliable anticorrosion method and apparatus for a long period of time, which can prevent the topcoat film on the conductive coating film from deteriorating. And.

In order to solve the above problems, in one aspect of the present invention, an insulating coating film is formed on the structure, a conductive coating film is formed on the insulating coating film, and the conductive coating film is first. An anode is electrically connected, a topcoat film is formed on the conductive coating film, a second anode is installed on the topcoat film, a DC voltage is applied to the first anode, and a direct current is applied to the second anode. This is an anticorrosion method for structures to which a voltage is applied.

Another aspect of the present invention is a structure in which an insulating coating film is formed, a conductive coating film is formed on the insulating coating film, and a top coat film is formed on the conductive coating film. A direct current voltage is applied to the first anode electrically connected to the conductive coating film, the second anode installed in the topcoat film of the structure, and the first anode, and direct current is applied to the second anode. It is an anticorrosion device for a structure including a power supply device for applying a voltage.

According to the present invention, since the second anode is installed on the topcoat film formed on the conductive coating film and a DC voltage is applied to the topcoat film, the topcoat film is electrically protected and the glossiness of the topcoat film is deteriorated. Is suppressed. Therefore, the life of the entire painted surface can be extended, and highly reliable electric corrosion protection can be performed for a long period of time.

It is a schematic diagram of the anticorrosion apparatus of one Embodiment of this invention. It is a figure which shows an example of the spacing of the 1st anode and the spacing of the 2nd anode. It is a circuit diagram of the constant voltage control unit of the power supply device of this embodiment. It is a circuit diagram of the constant current control unit of the power supply device of this embodiment.

Hereinafter, the anticorrosion method and the apparatus of the structure according to the embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the anticorrosion method and the apparatus of the structure of the present invention can be embodied in various forms, and are not limited to the embodiments described in the present specification. The present embodiment is provided with the intention of allowing those skilled in the art to fully understand the scope of the invention by adequately disclosing the specification.
(Configuration of anticorrosion device)

FIG. 1 is a schematic view of an anticorrosion device according to an embodiment of the present invention. 1 is a structure, 4 is a first anode, 6 is a second anode, and 7 is a power supply device. First, the structure 1 will be described.

The structure 1 is made of steel or the like. An insulating coating film 2 is formed on the entire surface of the structure 1. The paint constituting the insulating coating film 2 is an organic resin such as epoxy, urethane, acrylic, etc., which has a proven track record as a paint material.

A conductive coating film 3 that can be energized is formed on the insulating coating film 2. The paint constituting the conductive coating film 3 is made of an organic resin such as epoxy, urethane, or acrylic, which has a proven track record as a paint material, as a base material, and is mixed with conductive particles or powder such as carbon particles to have conductivity. It is a conductive paint adjusted for. If necessary, metal powders such as nickel, aluminum, and zinc can be used in combination with the carbon particles. The conductivity of the conductive coating film 3 is preferably 10 Ω / cm to 10,000 Ω / cm, preferably 20 Ω / cm to 1,000 Ω / cm, and more preferably 20 Ω / cm to 500 Ω / cm in an atmospheric environment. be.

The conductive coating film 3 is formed on a part 100 of the insulating coating film 2. The discontinuously shaped portion of the structure 1, that is, the non-planar portion 1a is prone to rust in a short period of time. The conductive coating film 3 is formed on a portion 100 of the insulating coating film 2 including the non-planar portion 1a.

The first anode 4 is electrically connected to the conductive coating film 3. The first anode 4 supplies electric power to the conductive coating film 3. The first anode 4 is made of a thin plate of stainless steel or copper. A DC voltage of, for example, 3 to 4 V is applied to the first anode 4, and a current of, for example, 0.01 to 0.1 mA flows.

The first anode 4 is electrically attached to the conductive coating film 3 by mounting the first anode 4 on the insulating coating film 2 and then forming the conductive coating film 3 on the insulating coating film 2. It may be electrically connected to the conductive coating film 3 by mounting the first anode 4 on the conductive coating film 3.

A weather-resistant or insulating topcoat film 5 is formed on the remaining portion 200 (the portion where the conductive coating film 3 is not formed) of the conductive coating film 3 and the insulating coating film 2. As the paint constituting the topcoat film 5, a paint having a proven track record as a paint on the outer surface of the structure 1 is used. For example, an insulating paint such as a vinyl-modified epoxy resin paint obtained by increasing the molecular weight of an epoxy resin using a modifier, or a hydrophobic paint such as an aqueous self-crosslinking acrylic emulsion paint can be used.

The second anode 6 is installed on the topcoat film 5 so as to be exposed to the atmosphere. The second anode 6 supplies electric power to the topcoat film 5. The second anode 6 is made of, for example, aluminum. A DC voltage of, for example, 20 to 50 V is applied to the second anode 6, and a current of, for example, 0.05 to 1.00 mA flows through the second anode 6.

The first anode 4 is connected to the terminal 8b of the power supply device 7. The second anode 6 is connected to the terminal 8a of the power supply device 7. The terminal 8c of the power supply device 7 is grounded by the ground 10. The structure 1 is grounded by the ground 9. It is also possible to connect the terminal 8c of the power supply device 7 to the structure 1.

The power supply device 7 applies an independent voltage and current to each of the first anode 4 and the second anode 6. Maximum DC output voltage applied to the second anode 6 by the power supply device 7: The maximum DC output voltage applied to the first anode 4 by the power supply device 7 is 3 to 17: 1. The configuration of the power supply device 7 will be described later.

As described above, a relatively high voltage is applied to the second anode 6 using the water film on the surface of the topcoat film 5 as the conductive medium, and a wide range of corrosion protection is achieved. Moreover, since the effective current is low with respect to the output current, a relatively high current value is set to improve the accuracy of corrosion protection. Since the first anode 4 using the conductive coating film 3 as a conductive medium is not significantly affected by the atmospheric environment, a relatively low voltage and current can be set in consideration of overcorrosion. The detailed configuration of the power supply device 7 will be described later.

As shown in FIG. 2, the number of the first anode 4 and the second anode 6 is determined by the shape and area of the structure 1 to be covered, and is usually a plurality of each. The effective range of the first anode 4 is, for example, a radius of 7 m of the conductive coating film 3 portion centered on the first anode 4. The effective range of the second anode 6 is, for example, a radius of 2.5 m to 3.0 m of the topcoat film 5 portion centered on the second anode 6. The distance P1 (P1 = 7 m × 2) between the adjacent first anodes 4 is longer than the distance P2 (P2 = 2.5 m to 3.0 m × 2) between the adjacent second anodes 6.
(Effect of anticorrosion device)

According to the anticorrosion device of the present embodiment, the following effects are obtained.

Since a DC voltage is applied to the first anode 4, an anticorrosion current can flow between the conductive coating film 3 and the structure 1 in the direction opposite to the corrosion current, and corrosion of the structure 1 can be suppressed. ..

When a DC voltage is applied to the first anode 4, the glossiness of the topcoat film 5 of the conductive coating film 3 decreases, and the topcoat film 5 deteriorates. However, since the second anode 6 is installed on the topcoat film 5 and a DC voltage is applied to the second anode 6, the topcoat film 5 is electrically protected and the deterioration of the glossiness of the topcoat film 5 is suppressed. Therefore, the life of the entire painted surface can be extended, and highly reliable electric corrosion protection can be performed for a long period of time.

Since an independent anticorrosion current is supplied to the first anode 4 and the second anode 6, the anticorrosion using the water film on the topcoat film 5 as the conductive medium and the anticorrosion using the conductive coating film 3 as the conductive medium, respectively. Function is improved. It is easy to optimize the conductivity of the conductive coating film 3, and in addition to reducing the cost of the coating film, deterioration and deterioration of the coating film are improved.

Since the conductive coating film 3 is formed on a part 100 of the insulating coating film 2, that is, on a part 100 including a discontinuously shaped non-planar portion 1a where rust is likely to occur in a short period of time, the conductive coating film 3 is formed. The portion forming 3 can be reduced, and economic efficiency can be ensured. On the other hand, if the conductive coating film 3 is formed on the entire surface of the insulating coating film 2 as in the conventional case, the cost of the coating film and the coating work becomes high, and there is a difficulty in economy.
(Configuration of power supply device)

The power supply device 7 of the present embodiment includes a constant voltage control unit 41 (see FIG. 3) and a constant current control unit 42 (see FIG. 4). The constant voltage control unit 41 includes one for the first anode 4 and one for the second anode 6. The configuration of the constant voltage control unit 41 for the first anode 4 and the configuration of the constant voltage control unit 41 for the second anode 6 are substantially the same. The constant current control unit 42 may be arranged in the case of the power supply device 7, or may be built in the first anode 4 and the second anode 6.

FIG. 3 is an example of a circuit diagram of the constant voltage control unit 41. A power plug 11 is connected to a commonly used AC power supply of 100 to 200 V, the input AC voltage is stepped down by a transformer 14, and converted into direct current by a rectifier circuit 15. Here, in order to prevent the constant voltage control unit 41 from being destroyed by an excess voltage or an excess current, a fuse 12 and / or a varistor 13 may be inserted on the primary side of the transformer 14. The output voltage on the secondary side of the transformer 14 is set to 3 to 4 V (for the first anode 4) or 20 to 50 V (for the second anode 6). The regulator 18 finely adjusts the output voltage to make the output voltage of the constant voltage control unit 41 constant. The capacitors 16, 17, 19 and 20 around the regulator 18 suppress and absorb voltage fluctuations and / or disturbance noise to help stabilize the output voltage. Further, the light emitting diode 21 and the resistor 22 are inserted in parallel between the anode and the cathode of the output unit of the constant voltage control unit 41, and the operation of the constant voltage control unit 41 is visually displayed by the light emission of the light emitting diode 21. do.

FIG. 4 is an example of a circuit diagram of the constant current control unit 42. 27 is a load resistance. The electric power controlled to a constant voltage by the constant voltage control unit 41 is applied to the transistor 24. The transistor 24, the resistor 23, the Zener diode 25, and the resistor 26 are controlled so that the current does not flow more than a predetermined value, and power is supplied to the load 27. The LED 29 displays a power input. The resistor 28 minimizes the current flowing through the LED.

The external power source of the power supply device 7 is not limited to the commercial power source. In order to secure long-term corrosion protection for steel towers in depopulated areas where commercial power cannot be obtained, solar cells and wireless power supply devices can be used in addition to commercial power. In the wireless power supply device, the power transmission side converts the current into an electromagnetic wave, the power receiving side receives the electromagnetic wave from the antenna, and the rectifier circuit converts the electromagnetic wave into an electric current.

A 20 mm × 50 mm × t2 mm copper plate was used as the first anode 4. After forming the insulating coating film 2 on the structure 1, the first anode 4 was attached to the insulating coating film 2 with double-sided tape. The distance between the first anodes 4 was set to 14 m. After that, the conductive coating film 3 was formed on a part 100 of the insulating coating film 2 so as to be electrically connected to the first anode 4.

The topcoat film 5 was formed on the remaining portion 200 of the insulating coating film 2 on which the conductive coating film 3 was not formed, and on the conductive coating film 3. As the second anode 6, a rectangular parallelepiped made of aluminum having a size of 50 mm × 50 mm × 15 mm was used. The second anode 6 was attached onto the topcoat film 5 with double-sided tape. The distance between the second anodes 6 was set to 5 m.

As the external power source of the power supply device 7, a commercial power source of 100 V was used. The maximum output of the power supply device 7 is DC4V, 10mA for the first anode 4 (corresponding to the first anode 4 of 20ch), and DC50V, 200mA for the second anode 6 (corresponding to the second anode 6 of 20ch). It was possible). As the power supply device 7, a device that automatically shuts off with a surge current and automatically recovers is used. A DC voltage of 3 V was applied to the first anode 4, and a DC voltage of 50 V was applied to the second anode 6.

It was confirmed by exposure tests and other demonstration experiments that the glossiness of the topcoat film 5 was maintained for a long period of time. Deterioration of the surface of the topcoat film 5 due to ultraviolet rays was significantly suppressed as compared with the case of the first anode 4 alone. It has become possible to provide highly reliable anticorrosion that cannot be achieved by conventional anticorrosion methods. Further, although the conventional anticorrosion method has been remarkably limited in its use in terms of cost, it has been found that the present invention can be applied to a wide variety of structures 1 in terms of cost.

1 ... Structure 2 ... Insulating coating film 3 ... Conductive coating film 4 ... First anode 5 ... Topcoat film 6 ... Second anode 7 ... Power supply device 100 ... Part of insulating coating film 200 ... Insulating coating film Remaining part P1 ... Spacing between the first anodes P2 ... Spacing between the second anodes

Claims (6)

An insulating coating film is formed on the structure, a conductive coating film is formed on the insulating coating film, a first anode is electrically connected to the conductive coating film, and the conductive coating film is coated on the conductive coating film. A method for preventing corrosion of a structure in which a topcoat film is formed on the topcoat film, a second anode is installed on the topcoat film, a DC voltage is applied to the first anode, and a DC voltage is applied to the second anode. The structure according to claim 1, wherein the conductive coating film is formed on a part of the insulating coating film, and the top coating film is formed on the remaining portion of the insulating coating film. Anti-corrosion method. The method for preventing corrosion of a structure according to claim 1, wherein the maximum output voltage of the direct current applied to the second anode: the maximum output voltage of the direct current applied to the first anode is 3 to 17: 1. .. The anticorrosion method for a structure according to claim 1 or 2, wherein the distance between the adjacent first anodes is longer than the distance between the adjacent second anodes. The anticorrosion method for a structure according to claim 1 or 2, wherein the DC voltage power source includes at least one of a commercial power source, a solar cell, and a wireless power feeding device. An insulating coating film is formed, a conductive coating film is formed on the insulating coating film, and an overcoat film is formed on the conductive coating film. The first anode connected to, and
A second anode installed on the topcoat film of the structure, and
A structure anticorrosion device comprising a power supply device for applying a DC voltage to the first anode and applying a DC voltage to the second anode.

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