JP2006328505A - Electric corrosion protection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic corrosion protection device normally operating in the air. <P>SOLUTION: The electrolytic corrosion protection device is provided with: a corrosion protection insulating film-coated layer formed on the surface of a metallic body to be subjected to corrosion protection; an electrically conductive coated layer formed on the surface of the corrosion protection insulating film-coated layer, and to which electric conductivity is imparted by the mixing of a carbon nanotube capable of obtaining high electric conductivity by a small mixing amount, and further capable of obtaining high electric conductivity by a small mixing amount, thus giving no damage to the color of a coating material; an anode mounted on a part of the electrically conductive coated layer; and D.C. power source applying positive potential to the anode, and applying negative potential to the metallic body to be subjected to corrosion protection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an anticorrosion device that protects metal structures such as bridges, footbridges, various storage tanks, and roofs from rust.

The cathodic protection itself has been used for a long time as a metal anticorrosion method. However, in order for the anticorrosion to be established, it is a condition that the anticorrosion current reaches the metal portion where the anticorrosion coating layer is missing from the anode. That is, current must flow outside the metal.
For this reason, the anti-corrosion method is effective for structures in the seawater or in structures such as splash zones, water, and underground where the surface is always wet with seawater, but for structures in the atmosphere. Has been considered ineffective.
In recent research, it is known that even in structures in the atmosphere, a thin water film is formed on the surface by moisture, and a small amount of current flows. In structures near the coast, the surface water film contains electrolytes such as salt, so current is said to flow more easily. In addition, even in the inland area, it is said that current flows easily when rainy or atmospheric humidity increases.

In this way, when anti-corrosion is used for structures in the atmosphere, current flows through the naturally formed surface water film, and the conductivity is greatly affected by natural conditions such as atmospheric electrolytes and humidity of the day. Is done. In order to expect a stable anticorrosion effect, it is necessary to arrange a large number of positive electrodes with a short interval so that the anticorrosion current can reach the entire surface of the structure.
An anticorrosion method in which an anticorrosive insulating coating layer having an insulating property is applied to the surface of a metal anticorrosive body and the anticorrosive current reaches the entire surface of the anticorrosive body through the conductive coating layer is disclosed in Patent Document 1, It is proposed in Patent Document 2, Patent Document 3, and the like.
JP 2001-335974 A JP 2003-96581 A JP-A-11-29886

  The conductive coating layer used in the conventionally proposed cathodic protection methods uses conductive materials such as carbon black, nickel, magnesium, aluminum, brass, copper, and graphite as the conductive material. Since these conductive materials have poor light transmission, the color of the paint is black or dark, such as brown, and when this is applied to the surface of the body to be protected, the scenery is worsened, or pressure is applied to neighboring houses. Failures such as giving a feeling occur. In particular, when carbon black is used as the conductive material, there is a drawback that color fading occurs due to contact and the color adheres to the other party.

  An object of the present invention is to propose an anticorrosion apparatus using a conductive coating layer having a light color tone and no color fading.

The present invention is characterized in that the conductive coating layer is formed using a conductive paint imparted with conductivity by mixing carbon nanotubes.
As is well known, carbon nanotubes have high conductivity, and high conductivity can be obtained even with a small amount of mixing, and since the amount of mixing can be small, color mixing properties for pigments of various colors (pigment original The rate of changing the color) is low.

  Since carbon nanotubes have high conductivity and low color mixing properties, a wide range of objects to be protected while in the air can be obtained by forming a conductive coating layer on the surface of the object to be protected with a conductive paint mixed with carbon nanotubes. Corrosion-proof current can be passed over. As a result, an anticorrosion apparatus having high anticorrosion performance can be configured. Further, since the color mixing property is low, there is an advantage that the color of the paint can be freely selected. Furthermore, there is no color fading, and inconveniences such as color adhering to the contact partner during contact are eliminated.

The cathodic protection device according to the present invention applies an insulating paint to the surface of a metal structure such as a bridge, a pedestrian bridge, various storage tanks, and a roof, and forms an anticorrosive insulating coating layer. After the anticorrosive insulating coating layer is cured, a carbon nanotube-mixed paint is applied to the upper surface of the anticorrosive insulating coating layer, and a conductive coating is applied to the upper surface of the anticorrosive insulating coating layer. It is formed.
The conductive coating layer may be formed on the entire surface of the metal structure in the same manner as the anticorrosion insulating coating layer, or may be formed in a predetermined pattern such as a strip shape or a lattice shape. A positive electrode is attached to the conductive coating layer, a negative electrode is attached to the metal structure, and a DC voltage of about 10 to 20 V is applied between the positive electrode and the negative electrode to constitute an anticorrosion device.

FIG. 1 shows an embodiment of the cathodic protection device according to the present invention. In the figure, reference numeral 1 denotes a metal protection body. As described above, the protection object 1 may be a bridge, a footbridge, various storage tanks, a roof, or the like.
An anticorrosive insulating coating layer 2 is deposited on the surface (entire surface) of the anticorrosive body 1. The anticorrosive insulating coating layer 2 can be formed by applying a metal paint having insulating properties that is usually used.
A conductive coating layer 3 is deposited on the top surface of the anticorrosive insulating coating layer 2. In the present invention, the conductive coating layer 3 is characterized in that it is formed by mixing carbon nanotubes into a paint and applying a conductive paint imparted with conductivity by the carbon nanotubes. As is well known, the carbon nanotube has a characteristic of high conductivity, and high conductivity can be obtained with a small mixing amount. Further, since the carbon nanotubes can be mixed in a small amount, the color of the paint is not changed by mixing the carbon nanotubes. Therefore, a conductive paint can be easily obtained by a paint having a color that matches the surrounding environment. In Example 1 shown in FIG. 1, the conductive coating layer 3 is formed on the entire surface of the corrosion-protected body 1.

A positive electrode 4 is attached to the conductive coating layer 3. The positive electrode 3 is formed of a highly conductive metal such as aluminum. Similarly, a negative electrode 5 made of aluminum or the like is attached to the body 1 to be protected, and a DC voltage of about 10 to 20 V, for example, is applied between the positive electrode 4 and the negative electrode 5.
When the defect portion 7 is generated in a state where a DC voltage is applied between the positive electrode 4 and the negative electrode 5, the anticorrosion current _ID flows as shown in FIG. The defect portion 7 refers to a state in which holes are generated in both the conductive coating layer 3 and the anticorrosive insulating coating layer 2 and a part of the surface of the corrosion-protected body 1 is exposed. When the defect portion 7 is generated, the anticorrosion current _ID flows from the conductive coating layer 3 toward the object 1 to be protected, and the anticorrosion current _ID can prevent the progress of the anticorrosion.

FIG. 3 shows a second embodiment of the cathodic protection device according to the present invention. Example 2 shows a case where the conductive coating layer 3 is formed in a strip shape. A plurality of strip-shaped conductive coating layers 3 are formed in parallel with each other on the surface of the anticorrosive insulating coating layer 2, and a positive electrode 4 is attached to each conductive coating layer 3. The negative electrode 5 is mounted. A DC power source 6 is connected between each positive electrode 4 and negative electrode 5.
Thus, even when the conductive coating layer 3 is formed in a belt-like pattern, the anticorrosion current can be spread over the entire surface of the structure using the natural surface water film between the conductive coating layers 3. . According to this Example 2, although the usage-amount of a conductive coating material can be suppressed and cost can be reduced, the same anticorrosion effect as Example 1 can be acquired.

  FIG. 4 shows a third embodiment of the cathodic protection device according to the present invention. In this embodiment, the conductive coating layer 3 is formed in a lattice shape. Thus, when the electroconductive coating layer 3 is formed in a lattice shape, the utilization form of the surface water film between the electroconductive coating layers 3 is surely executed, and the reliability of the anticorrosion action is enhanced.

  FIG. 5 shows a fourth embodiment of the cathodic protection device according to the present invention. In this embodiment, the surface of the spherical gas tank is covered with the anticorrosive insulating coating layer 2, and advertising characters 8 or pictures 9 are drawn on the upper surface of the anticorrosive insulating coating layer 2 with the conductive coating layer 3. And the case where it comprises so that it may act as an anticorrosion apparatus by applying a positive potential to the part of the picture 9 is shown. In the present invention, since carbon nanotubes are mixed into the paint to obtain conductivity, the carbon nanotubes do not make the color of the paint turbid. For this reason, paints of various colors can be easily obtained, so that the advertising character 8 or the picture 9 can be freely drawn without being limited to the color of the paint, and both advertisement and anticorrosion can be achieved. Benefits that can be obtained.

  Although FIG. 5 shows an example applied to a spherical gas tank, it is clear that the present invention can be applied to other structures, and its application will be widely considered.

  The cathodic protection device according to the present invention is used in the anticorrosion field of metal structures such as bridges, footbridges, various storage tanks, and roofs.

Sectional drawing for demonstrating Example 1 of this invention. Sectional drawing for demonstrating the effect | action of the Example shown in FIG. The front view for demonstrating Example 2 of this invention. The front view for demonstrating Example 3 of this invention. The front view for demonstrating Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Corrosion object 6 DC power supply 2 Corrosion-proof insulation coating layer 7 Defect part 3 Conductive coating layer 8 Character 4 Positive electrode 9 Picture 5 Negative electrode

Claims (4)

An anti-corrosion insulating coating layer deposited on the surface of the metal anti-corrosion body;
A conductive coating layer deposited on the surface of the anticorrosive insulating coating layer, and provided with conductivity by mixing carbon nanotubes;
A positive electrode attached to a part of the conductive coating layer;
A direct current power source that applies a positive potential to the positive electrode and applies a negative potential to the metal corrosion protection body,
A cathodic protection device comprising:   2. The cathodic protection device according to claim 1, wherein the conductive coating layer is deposited on substantially the entire surface of the anticorrosion insulating coating layer.   2. The cathodic protection device according to claim 1, wherein the conductive coating layer is deposited on the surface of the anticorrosion coating layer in a predetermined pattern shape.   4. The cathodic protection device according to claim 1, wherein the conductive coating layer is drawn in a pattern such as letters and pictures on the surface of the anticorrosion insulating coating layer.

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