JPH0814036B2 - Antifouling equipment for structures in contact with seawater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an antifouling device for structures that come into contact with seawater, such as ships and marine structures.

[Conventional technology]

As a means for antifouling structures that come into contact with seawater such as ships and marine structures, a means for applying antifouling paint to the water contacting parts of the structures has been generally adopted.

However, such means have the following drawbacks.

(1) Since the elution rate of the antifouling component of the antifouling paint cannot be adjusted, it is not possible to respond flexibly to the season, ocean currents, water quality changes, etc.

(2) Since the content of toxic substances in the antifouling paint is limited, repainting work is required about every two years.

Therefore, the present applicant previously filed Japanese Patent Application Nos. 61-247032 and 61-248897, and as shown in the schematic diagram of FIG. 5, the structure 1 in contact with the seawater 2 is insulated with an epoxy resin or the like. The coating film 3 and the conductive coating film 05 in which carbon powder or the like is mixed with an organic binder are applied repeatedly, and the conductive coating film 05 is formed between the conductive coating film 05 and the electric conductor 6 made of steel or the like by the DC power supply 7 ( Conductor coating is performed by turning the electric conductor 6 to (-) and then energizing it.
On 05, 2Cl ^- proposed a device for generating chlorine by the action of → Cl ₂ + 2e.

However, it has been found that such a device has the following problems.

(1) It is necessary to keep the current density flowing into the ocean 2 at a certain value or more, but the current density is concentrated near the current-carrying end due to the resistance increase due to the consumption of the conductive coating film 05, and the antifouling effective range is Narrows.

(2) It is difficult to maintain the performance because the current density varies depending on the thinness of the conductive coating film 05.

(3) A low resistance conductive coating film 05 is required for uniforming the current density, but for that purpose it is necessary to mix a large amount of conductive powder, which makes manufacturing difficult.

[Problems to be Solved by the Invention]

The present invention has been proposed in view of such circumstances, and it is possible to prevent an increase in resistance due to consumption of the conductive coating film in an antifouling device using the conductive coating film, and also to prevent variations in the film pressure of the conductive coating film. An object of the present invention is to provide an antifouling device for a structure which is in contact with seawater, which can eliminate the non-uniformity of current distribution and can achieve a high-performance antifouling effect with a low resistance conductive coating film.

Also, if the outer conductive coating is applied over the inner conductive coating to prevent the resistance from increasing, the compatibility of those at the interface and the decrease in the conductivity of the film will lower the resistance of the film. Therefore, it is an object of the present invention to provide an antifouling device for a structure in contact with seawater, which prevents the current density from concentrating near the energizing end and narrowing the effective antifouling range.

[Means for solving the problem]

To this end, the present invention provides a specific resistance in which a conductive end is provided by covering the outside of an electric insulator on the water contact surface of a structure that is in contact with seawater such as a ship or an offshore structure, and including a conductive material, a small piece, and an organic binder. A small inner conductive coating, consisting of a small piece of an oxidation resistant and insoluble conductive material coating the outside of the inner conductive coating and an organic binder, the specific resistance ratio of the inner conductive coating is 10
An outer conductive coating film having a large specific resistance of at least twice to at least 156 times, an electric conductor that is installed in seawater facing the outer conductive coating film, a current-carrying end of the inner conductive coating film, and the electric conductor. And a power supply device that is installed between the inner conductive coating film and the outer conductive coating film and applies a direct current to the electric conductor.

Further, between the inner conductive coating and the outer conductive coating, an organic conductive coating of a small piece of a conductive material, an intermediate conductive coating having a specific resistance between the outer conductive coating and the inner conductive coating. It is characterized by being painted.

[Work]

With the above configuration, it is possible to prevent an increase in resistance due to consumption of the conductive coating film in the antifouling device using the conductive coating film.
(EN) An antifouling device for a structure in contact with seawater, which can eliminate the uneven current distribution due to the variation in the film thickness of the electrically conductive film, and can have a high-performance antifouling effect with the low resistance electrically conductive film. be able to.

Further, since it is possible to prevent the conductivity of the inner conductive coating film from being lowered, the antifouling range of the device is not limited, and the antifouling device for a structure in contact with seawater that can improve its economical efficiency and antifouling property is provided. Obtainable.

〔Example〕

An embodiment of an antifouling device for a structure in contact with seawater according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the first embodiment, and FIG. 2 is an electric conduction effect by the two-layer conductive coating film of FIG. FIG. 3 is a diagram showing the distance in comparison with the conventional device, FIG. 3 is a schematic diagram showing the second embodiment, and FIG. 4 is a diagram showing changes with time of electric resistance due to the three-layer conductive coating film of FIG. Is.

First, in FIG. 1, reference numeral 1 is a steel plate constituting an outer plate of a steel structure which is in contact with seawater 2, and 3 is an insulating coating film as an electric insulator made of epoxy resin or the like for coating the outside of the steel plate 1.
If the outer plate is an electrical insulator such as FRP, the insulating coating may be omitted. Reference numeral 4 denotes an inner conductive coating film that covers the outside of the insulating coating film 3 and has a small specific resistance, a metal oxide and an organic binder, and is provided with a current-carrying end 4a. Conductive agents such as copper, titanium and niobium, and conductive materials such as magnetite and manganese dioxide can be used as metal oxides, respectively, and the shape of the mixture with the organic binder is powdery, linear, filler or flake. It can be applied in small pieces. As the organic binder, epoxy resin, vinyl resin, unsaturated polyester resin, acrylic resin, phenol resin, urethane resin, vinyl ester epoxy resin or the like can be used.

Reference numeral 5 denotes an outer conductive coating film made of an organic binder and a small piece of an oxidation resistant and insoluble conductive material which further covers the outer side of the inner conductive coating film 4. Graphite and carbon black are used as the small pieces of the oxidation resistant and insoluble conductive material. , Magnetite, white metal, etc. can be used, and the same resins as the above can be used as the organic binder. Further, the outer conductive coating film 5 has a larger electric resistance than the inner conductive coating film 4.

Reference numeral 6 is a cathode as an electric conductor made of iron, copper, carbon or the like, which is installed in the seawater 2 so as to face the outer conductive coating film 7,
Is installed between the current-carrying end 4a of the inner conductive coating film 4 and the cathode 6, and the cathode 6 passes from the inner conductive coating film 4 through the outer conductive coating film 5.
It is a DC power supply that supplies DC in the direction of. Reference numeral 8 is a lead wire that connects the steel plate 1 and the cathode 6.

In such an apparatus, when a direct current is caused to flow from the inner conductive coating film 4 through the outer conductive coating film 5 toward the cathode 6 in the seawater 2, the surface of the outer conductive coating film 5 is covered with a dense chlorine film. , Prevent marine life from attaching to its surface.

At this time, the direct current is supplied from the current-carrying end 4a provided on the inner conductive coating film 4 through the base current of the inner conductive coating film 4 having a small electric resistance in the thickness direction of the outer conductive coating film 5. Therefore, even if the outer conductive coating film 5 is consumed, the current density does not concentrate near the conductive end 4a, and a stable and uniform current density distribution can be maintained for a long period of time. A dirty effect can be produced.

In addition, since the steel plate 1 is set to the (−) potential and the inner and outer conductive coating films 4,5 are set to the (+) potential by the lead wire 8, the inner and outer conductive coating films 4,5 are locally formed. When the steel sheet 1 is exposed to damage and is exposed to damage, a part of the direct current flowing out from the conductive coating films 4 and 5 flows into the exposed portion of the steel sheet and returns from the steel sheet 1 to the (-) pole of the DC power supply 7. Corrosion of the steel plate 1 is prevented.

When the outer conductive coating 5 is damaged and the inner conductive coating 4 is exposed, it is important to use titanium, niobium, metal oxide or the like as a material for the inner conductive coating 4 in order to prevent chemical elution thereof. It is effective for long-term stabilization of the device.

However, in such a device, the inner conductive coating 4
Electrical resistance R ₄ in the direction parallel to the steel plate 1 <is related outer guide Den'nurimaku electrical resistance R ₅ in a direction parallel to the steel plate 1 of 5, energization end
R ₄ / R ₅ 0.1 is preferable in order to make uniform the current density distribution by flowing about 95% of the current received from 4a in the inner conductive coating film 4, and the thickness of the conductive coating films 4,5 is volume resistance. Rate and conductive coating 5
It is necessary to decide it by taking into account the power consumption of the vehicle and the consumption due to the external environment.

Here, an experimental example will be described with reference to FIG. 2, which shows a comparison of the effective energization distance from the energization end of the conductive coating in the device of the present invention and the conventional device. Is as follows.

Device of the present invention Inner conductive coating: resistance 0.32 Ω-m, film thickness 200 μ Outer conductive coating: resistance 30 Ω-m, film thickness 100 μ Note that the ratio of the resistance between the inner conductive coating and the outer conductive coating is 94.
Doubled conventional device Conductive coating: resistance 3Ω-m, film thickness 200μ When 80mA is applied to such a conductive coating from the energizing end,
The conventional device b has a length of 3 m for holding the required current density A, while the device a of the present invention is effective up to 13 m. Further, in the device of the present invention, the thickness of the inner conductive coating film is changed from 200 μm to 20 μm.
Although the effective distance did not change even when the value changed to, it decreased to 1 m as in the case of the conventional device.

Next, FIG. 3 shows, in the second embodiment, the same reference numerals as those in FIG. 1 respectively show the same members as in FIG. In the intermediate conductive coating film, as the small pieces of the conductive material and the organic binder, those similar to the outer conductive coating film 5 or the inner conductive coating film 4 can be used. As the organic binder of the intermediate conductive coating film, those having a low compatibility with the organic binder of at least one of the outer conductive coating film 5 and the inner conductive coating film 4 are desirable, and particularly, a reaction curable urethane resin, an epoxy resin. And the like are preferable.

In such a device, when a direct current is caused to flow from the inner conductive coating film 4 through the intermediate conductive coating film 9 and the outer conductive coating film 5 toward the cathode 6 in the seawater 2, the outer conductive coating film 5 has a dark surface. Covered with a chlorine film, it prevents marine life from attaching to its surface.

The basic flow of the direct current at that time is the same as that of the first embodiment, and the steel plate 1 is set to the (−) potential by the lead wire 8 and the inner, middle and outer conductive coating films 4, 9 and 5 ( +) Potential, so the inner, middle and outer conductive coating 4,
When 9,5 is locally damaged and destroyed and an exposed part is formed on the steel plate 1, part of the direct current flowing out from the inner, middle and outer conductive coatings 4, 9, 5 flows into the exposed part of the steel plate 1. The corrosion of the steel sheet 1 returned from the steel sheet 1 to the (−) pole of the DC power supply 7 is prevented.

Further, when the inner and outer conductive coating films 9 and 5 are damaged and destroyed and the inner conductive coating film 4 is exposed, titanium, niobium, metal oxide or the like is used as the material of the inner conductive coating film 4 to prevent chemical elution thereof. This is effective for long-term stabilization of the device. The thickness of the inner, middle and outer conductive coatings 4, 9 and 5 must be determined in consideration of the volume resistivity and the wear of the middle and outer conductive coatings 9 and 5 due to energization and the external environment.

In such an apparatus, by providing the intermediate conductive coating film 9 as a barrier between the inner conductive coating film 4 and the outer conductive coating film 5, the resin of the inner conductive coating film 4 and the resin of the outer conductive coating film 5 are separated from each other. It is possible to prevent the increase in the resistance of the inner conductive coating film 4 by being compatible with each other.

By the way, when the change with time of the electric resistance of the coating film was experimentally obtained, good results shown in FIG. 4 were obtained. That is, in the figure, the o mark indicates the inner conductive coating film 4 as in the structure of FIG.
In the case of a two-layer conductive coating film in which the outer conductive coating film 5 is directly applied on top of it, the mark Δ indicates an intermediate conductive coating film 9 between them as shown in FIG.
The case of a three-layer conductive coating film coated as a barrier is shown respectively, and the conditions of each conductive coating film are as follows.

Inner conductive coating 4: Acrylic resin / copper coating
Resistance 0.32 Ω-m Intermediate conductive coating 9: Urethane resin / carbon-based coating Resistance 40 Ω-m Outer conductive coating 5: Vinyl resin / carbon-based coating Resistance 50 Ω-m In addition, inner conductive coating and outer conductive coating The resistance ratio with is 15
In the figure, which is 6 times larger, the vertical axis represents the electric resistance of the coating film, and the horizontal axis represents the elapsed time from the application of the outer conductive coating film 5 as the top coat to the resistance measurement. It was demonstrated that by applying the coating film 9, it is possible to completely prevent an increase in resistance of the coating film when the outer conductive coating film 5 is directly overlaid on the inner conductive coating film 4.

According to such an apparatus, by coating the outer conductive coating film on the inner conductive coating film through a specific intermediate conductive coating film, the conductivity of the inner conductive coating film is prevented from decreasing, so the antifouling range Is not limited, so that the economical efficiency and antifouling performance can be improved.

〔The invention's effect〕

Since the present invention is configured as described above, it has the following effects.

The specific resistance is small because the outer surface of the electrical insulator on the water contact surface of a structure in contact with seawater such as a ship or marine structure is covered with an electrically conductive material, a small piece, and an organic binder, and the conductive end is provided. Inner conductive coating, consisting of a small piece of oxidation-resistant insoluble conductive material that covers the outside of the inner conductive coating and an organic binder, the specific resistance ratio of the inner conductive coating is 10 times or more ~
An outer conductive coating film having a large specific resistance of 156 times or more, an electric conductor facing the outer conductive coating film and installed in seawater, and a current-carrying end of the inner conductive coating film and the electric conductor. And a power supply device for supplying a direct current to the electric conductor from the inner conductive coating through the outer conductive coating, the resistance increase due to consumption of the conductive coating in an antifouling device using the conductive coating. In addition, it is possible to prevent uneven current distribution due to variations in the thickness of the conductive coating film, and a high resistance anti-fouling effect with a low resistance conductive coating structure that comes into contact with seawater. Get an antifouling device for things.

In the antifouling device for a structure in contact with seawater according to claim (2), a small piece of a conductive material and an organic binder are provided between the inner conductive coating and the outer conductive coating, and the outer conductive coating and the outer conductive coating are provided. By coating the intermediate conductive coating film having a specific resistance between the inner conductive coating film, the inner conductive coating film is prevented from decreasing in conductivity, and the organic binder of the inner conductive coating film and the organic binder of the outer conductive coating film are separated from each other. In addition to the effect of claim (1), even when the outer conductive coating is directly applied on the inner conductive coating, the conductivity of those films does not decrease and the inner conductive coating and the outer conductive coating do not deteriorate. It is possible to further enhance the effect that the coating films are appropriately bonded and delamination is not likely to occur at the interface.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of an antifouling device for a structure in contact with seawater of the present invention, and FIG. 2 shows the effective current distance by the two-layer conductive coating film of FIG. 1 in comparison with a conventional device. A diagram, FIG. 3 is a schematic diagram showing the second embodiment, and FIG. 4 is a diagram showing changes with time in electric resistance due to the three-layer conductive coating film of FIG. FIG. 5 is a schematic view showing a conventional antifouling device. 1 ... Steel plate, 2 ... Seawater, 3 ... Insulating coating film, 4 ... Inner conductive coating film, 4a ... Current-carrying end, 5 ... Outer conductive coating film, 6 ...
Cathode, 7 ... DC power supply, 8 ... Lead wire, 9 ... Intermediate conductive coating film

Front page continuation (72) Inventor Kiyomi Tomomige 1-1, Atsunoura-machi, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (72) Inventor Tsutomu Horiguchi 5-7 Atsunoura-cho, Nagasaki-shi, Nagasaki Hyokou Building Annex 5F Choryo Engineering Co., Ltd. (72) Inventor Shozo Ohta 5-7, Atsunoura-cho, Nagasaki City, Nagasaki Ryokko Building Annex 5F Choryo Engineering Co., Ltd. (56) Reference JP-A-63-101464 ( JP, A) JP 61-27277 (JP, B2)

Claims (2)

[Claims] 1. An inner side having a small specific resistance, which covers an outer surface of an electric insulator of a water contact surface of a ship, a marine structure or the like which is in contact with seawater, and which is provided with a conductive end made of a conductive material, a small piece and an organic binder. Conductive coating, consisting of a small piece of an acid resistant and insoluble conductive material coating the outside of the inner conductive coating and an organic binder, the specific resistance ratio of the inner conductive coating is 10 times or more ~ 156
An outer conductive coating film having a large specific resistance not more than twice, and an electric conductor installed in seawater facing the outer conductive coating film,
A power supply device that is installed between the current-carrying end of the inner conductive coating and the electric conductor and that applies a direct current from the inner conductive coating to the electric conductor through the outer conductive coating. Antifouling device for structures that come into contact with seawater. 2. An intermediate having a specific resistance between the outer conductive coating and the inner conductive coating, comprising a small piece of an organic binder of a conductive material between the inner conductive coating and the outer conductive coating. The antifouling device for a structure in contact with seawater according to claim 1, wherein a conductive coating film is applied.