JPH10271942A - Member for electrochemical biological control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member for electrochemical biological control, stable even with time and applicable even to an underwater structure having a large area without causing the corrosion of a metal to be a substrate. SOLUTION: This member for electrochemical and biological control is obtained by joining an insulating resin film 3 through a bonding layer 2 to the surface of an electroconductive substrate 1 composed of a metal, joining an electroconductive sheet material 5 through a bonding layer 4 onto the insulating resin film 3 and forming an electroconductive coating film layer 6 on the electroconductive sheet material 5. An electroconductive composite layer 7 comprising the substrate metal, the electroconductive sheet material 5 and the electroconductive coating film layer 6 is completely insulated with the insulating resin film 3 without causing the electrochemical sticking or dissolution of the substrate metal 1 even when a potential is applied to the electroconductive composite layer 7. Furthermore, the electroconductive composite layer 7 comprising the electroconductive sheet material 5 and the electroconductive coating film layer 6 reduces the value of resistance from that of the electroconductive coating film layer 6 and the potential can be prevented from lowering due to the value of the resistance even at a site separate from the site for applying the potential. Since the set potential can thereby be applied to the surface of an underwater structure having a large aquatic organisms attached to the whole surface of the underwater structure can electrochemically be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member suitable for electrochemically controlling aqueous organisms attached to a water-contacting surface such as a ship, a cooling water intake pipe, a water distribution pipe, and the like.

[0002]

2. Description of the Related Art Many organisms exist in seawater and freshwater,
It shows pathogenicity and attaches to the surface of underwater structures, causing various problems. For example, when organisms adhere to a ship, problems such as an increase in propulsion resistance, and in a fixed net or an aquaculture net, problems such as the inhibition of seawater exchange and deformation of the net are caused. Furthermore, cooling pipes used in thermal power plants have problems such as a decrease in heat exchange efficiency, and the detachment of large organisms that have adhered to the inner surface of the cooling pipe and proliferate, resulting in blockage of the cooling pipe.

[0003] In general, the mechanism by which organisms adhere to the water contact surface is as follows. First, adherent Gram-negative bacteria adsorb to the surface and secrete a large amount of lipid-derived slime-like substances. Further, microorganisms gather and grow on the slime layer to form a microorganism film. Then, large aquatic organisms such as algae, shellfish, barnacles, etc. adhere to the microbial film layer, and the attached large aquatic organisms propagate and grow, and eventually cover the water contact surface.

[0004] As an antifouling means for aquatic organisms adhering to the surface of the underwater structure, a method of adding a bactericidal substance such as hypochlorite to seawater to kill the organisms,
2. Description of the Related Art In general, a method of forming a coating film on a ship or fishing net with a paint containing an organotin-based compound and dissolving the organotin-based compound to thereby prevent stains has been generally performed. However, the addition of bactericidal substances such as hypochlorite and the use of organotin compounds will react with organic substances in the water, causing harmful substances such as trihalomethane and the elution of organotin compounds. There is concern about pollution and its effects on useful marine life. Also,
Recently, non-organotin-based antifouling agents have been used as an alternative to organotin-based compounds.
Since the maintenance time of the anti-adhesion effect is short, the labor required for the repainting operation of the paint is greatly increased, and there is a problem that the cost is increased. Therefore, a new method for disinfecting living organisms and a new antifouling method are desired.

Recently, there has been proposed a method of electrochemically controlling aquatic organisms attached to ships and fishing nets without generating harmful substances such as chlorine. In this electrochemical control method, when a potential equal to or higher than a predetermined potential at which a direct reaction of the microorganism is confirmed is applied to the microorganism, coenzyme A, one of the redox substances inside the microorganism, is irreversibly oxidized, Induces a decrease in the respiratory activity of microorganisms and the permeability barrier of microbial membranes
It is known that microorganisms can be killed (Japanese Patent Publication No. Hei 6-91821). That is, it is a method of preventing the attachment of large organisms by electrochemically controlling the attachment of Gram-negative bacteria. Also, Japanese Patent Application Laid-Open No. 4-3
No. 41392 discloses that the surface to be stained having conductivity has a value of +0.
~ + 1.5V vs. A process of applying a positive potential of SCE to kill microorganisms adhering thereto, and a process of -0 to -0.4 V vs. S.
An antifouling method comprising a step of applying a negative potential of CE to detach living organisms is described.

[0006]

Since these methods do not cause degradation of seawater or water, there is no pollution of the ocean or water, and furthermore, the effects of marine organisms on ecosystems and food processing products are reduced. Absent, it is considered an excellent sterilization and antifouling method. As a specific method, a conductive resin layer is provided by coating a conductive rubber or a conductive coating film on the water contact surface, and a platinum or carbon electrode is arranged at the counter electrode, and the conductive resin layer and the counter electrode are provided between the conductive resin layer and the counter electrode. This is a method of controlling an organism by applying an electric potential. In particular, when the base material is made of metal, even if a conductive resin layer is formed on these metal base materials, the base metal is electrochemically corroded by pinholes formed in the conductive resin layer. For this reason, a method of providing an insulating coating layer on a metal has been proposed (Japanese Patent Application No. 63-84042, with a publication or publication number). However, since the insulating coating layer is formed of a paint containing a solvent, pinholes are easily generated. Furthermore, as a resin used in the coating material, a reaction-curable resin is superior to a thermoplastic resin, but a low-molecular monomer is reactively cured by heating using a crosslinking agent or a catalyst, so that a cured coating film Has a three-dimensional structure and has problems such as easy passage of moisture.

Further, the conductive resin layer is formed by dispersing conductive fine particles of oxidation resistance such as carbon black, graphite or metal oxide in a synthetic resin.
However, the specific resistance value of the conductive resin layer obtained by dispersing conductive particles of oxidation resistance such as carbon black or graphite in a synthetic resin depends on the amount of the conductive particles. 10 ² Ωcm or more. Therefore, in the case where the potential is uniformly applied to a large area, as the distance from the portion to which the potential is applied increases, the resistance value of the conductive resin layer increases accordingly, and as a result, the applied potential decreases. . Therefore, in an underwater structure having a large area, a decrease in potential may occur, and it may not be possible to prevent biological contamination of the entire surface of the underwater structure, and a countermeasure has been desired.

Further, a member in which a conductive sheet is joined to a conductive material via an electrically insulating material has also been proposed (Japanese Patent Laid-Open No. 3-1).
However, in a member having a water contact surface made of a conductive sheet material, there is a gap in the conductive sheet material, and the lower adhesive layer is in contact with seawater or fresh water through this gap, It was recognized that aquatic organisms penetrated from the voids and adhered to the surface of the adhesive layer, and then the attached aquatic organisms proliferated to form a microbial film, and large aquatic organisms adhered thereto and grew. In addition, the growth of large aquatic organisms causes peeling of the conductive sheet material, making it impossible to electrochemically control aquatic organisms.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electric machine which does not cause corrosion of a base metal, is stable over time, and can be applied to an underwater structure having a large area. By providing a chemical biological control member, the insulating resin film is bonded to the surface of the conductive base material made of metal via an adhesive layer, and the conductive resin is provided on the insulating resin film via the adhesive layer. The gist of the present invention is an electrochemical biological control member obtained by joining sheet materials and forming a conductive coating layer on the conductive sheet.

Hereinafter, the present invention will be described in detail. FIG.
It is the figure which showed typically the cross section of the member for electrochemical biological control obtained by this invention. In the figure, reference numeral 1 denotes a conductive substrate made of a metal, such as iron and its alloys, aluminum and its alloys, copper and its alloys, zinc and its alloys, and stainless steel. Since these base materials 1 are easily dissolved or corroded electrochemically, the insulating resin film layer 3 is bonded to the base material 1 via the adhesive layer 2. In addition, on the surface of the base material 1, in order to enhance the adhesion between the base material 1 and the adhesive layer 2, a chemical composite oxide film such as a phosphoric acid film or a chromate film, an oxide film formed by anodic oxidation such as alumite, or It is preferable to form a black chrome plating film.

Next, the adhesive layer 2 for joining the insulating resin film 3 onto the metal material may be appropriately selected depending on the materials of the metal material 1 and the insulating resin film 3, and is not particularly limited. When the insulating resin film 3 is laminated on the inner surface of the pipe, a pressure-sensitive adhesive or a hot-melt adhesive is preferable in terms of workability. In the case of a relatively flat and large area such as a hull, a rubber-based adhesive, an epoxy-based adhesive, a pressure-sensitive adhesive, or a hot-melt adhesive may be used. In the case where a composite oxide film or an oxide film is formed on the substrate 1, it is more preferable to use an adhesive suitable for the material of the insulating resin film 3. These adhesive layers 2 may be formed on the insulating resin film in advance, or may be formed on the metal material 1. still,
When forming the adhesive layer 2 on the base material 1, the forming method is as follows.
A roll coater, a spray method, a coating method using a brush, or the like can be employed, and is not particularly limited.

Further, the insulating resin film 3 to be laminated on the adhesive layer 2 may be a film made of a material having a high electrical insulation property and less swelling or deterioration in seawater or water. Resin, polyethylene resin, terephthalate resin, nylon resin, polypropylene resin, polyethylene resin, polyvinylidene chloride resin,
Polyamide-imide resin, polyimide resin, fluorine resin,
Silicon resin or the like is used. Although the surface of these resin films depends on the material of the resin film, in order to enhance the adhesiveness with the adhesive layer, plasma treatment, corona discharge treatment,
Alternatively, it is more preferable that a hydrophilic treatment is performed by etching treatment with chromic acid or the like. Further, the thickness of the resin film is not particularly limited, but is preferably 10 μm or more.

Next, the conductive sheet material 5 will be described.
The conductive sheet material 5 may be any material that does not dissolve or deteriorate electrochemically, and is made of, for example, a valve metal such as carbon fiber, titanium, zirconia, tantalum, and niobium. Also,
These valve metal films may be formed on carbon fibers by vapor deposition. The conductive sheet material made of these may be in a mesh shape, a woven shape, or a knitted shape.

The conductive sheet material 5 is made of an insulating resin film 3
And an adhesive layer 4. The adhesive used for the adhesive layer 4 is a rubber-based adhesive, an epoxy-based adhesive, a pressure-sensitive adhesive, or a hot-melt adhesive. The adhesive may be appropriately selected and used depending on the material, and particularly preferably an adhesive having excellent water resistance.

Next, the conductive coating layer 6 formed on the conductive sheet material 5 will be described. The conductive coating layer 6
Consisting of a binder resin and conductive fine particles, the conductive fine particles may be any material that does not elute or deteriorate chemically and electrochemically.Examples include oxides such as carbon black, graphite, tin oxide, and indium oxide, and nitrides. Preference is given to nitrides such as titanium, chromium nitride, zirconium nitride and tantalum nitride, carbides such as titanium carbide, zirconium carbide and tantalum carbide, and borides such as titanium boride, zirconium boride and tantalum boride. The shape of these conductive fine particles may be amorphous, scaly, spherical, or fibrous, and may be used alone or as a mixture of two or more. Further, the particle size may be about 0.001 μm to about 100 μm. The filling amount of the binder resin may be such that the specific resistance value of the obtained conductive coating layer 6 is 1 Ω · cm or less.

Next, the binder resin will be described in detail. As the binder resin, one that is dried or reactively cured at room temperature, one that is cured by heating, and an organic solvent type,
A water-soluble type, an emulsion type, etc. are used.Specifically, nitrocellulose, vinyl chloride, acrylic, polyamide resin, melamine, melamine algit resin, polyurethane elastomer, polyester elastomer, thermosetting acrylic resin, polyurethane resin, epoxy resin, Unsaturated polyester, amino resin, silicone resin, fluorine resin, polyvinyl acetate resin as water-soluble synthetic latex,
A vinegar-acrylic copolymer, polyvinyl chloride, a polyvinyl chloride-vinylidene chloride copolymer, a synthetic rubber latex, or the like is used and may be selected according to the purpose. The conductive coating layer 6 is formed on the conductive sheet material 5 by a spray method, a roll coater method, an electrostatic coating method, a brush coating method, or the like.

Next, the potential application conditions in the electrochemical control of living organisms will be described. When a positive potential is applied to the conductive composite layer 7 composed of the conductive sheet and the conductive coating layer 6 in the water containing living organisms, living organisms in the water can be adsorbed to the conductive composite layer 7. Further, the positive potential applied to the conductive composite layer 7 has an action of electrochemically sterilizing aquatic organisms that have been adsorbed and contacted with the surface of the conductive composite layer 7.
In other words, aquatic organisms are exposed to the conductive composite layer 7 by the positive potential.
Adsorbed on the surface and sterilized on the surface. The applied positive potential is between +0 and 1.5 V vs. SCE, preferably +
0.5 to +1.5 V vs. SCE, and when the applied potential is 0 V vs. SCE or less, the living thing is transferred to the conductive composite layer 7.
Cannot be sterilized by adsorption to +1.5
If a potential exceeding V vs. SCE is applied for a long time, water and dissolved salts are electrolyzed to generate harmful substances, which is not preferable. The time for applying a positive potential to the conductive composite layer 7 varies depending on the type and concentration of aquatic organisms present in the water, or the flow rate and temperature, but is preferably about 5 minutes to 6 hours, and when the application time is longer than 6 hours. However, since other aquatic organisms adsorb on the aquatic organisms sterilized on the conductive composite layer 7, the aquatic organisms adsorbed later are not in direct contact with the conductive composite layer 7, so that the aquatic organisms are not electrically contacted by the positive potential. Not subject to chemical bactericidal action.

After applying a positive potential for electrochemical sterilization for a certain period of time, to damage the cell wall of aquatic organisms,
A higher potential than the applied potential may be applied. The potential to be applied is preferably +1.5 to +2 V vs. SCE, but when a potential of +2 V vs. SCE or higher is applied, water and dissolved salts are electrolyzed and harmful gas bubbles are generated regardless of the application time. Is not preferred. Although the application time varies depending on the applied potential, it may be applied for a short time in which water and dissolved salts are electrolyzed and no harmful gas bubbles are observed, and specifically 1/1000 sec to 60 sec. Since the application time is short, even if water or dissolved salts are electrolyzed to generate harmful gas, the amount thereof is extremely small, so that the effect on the environment is not a problem. +0
~ + 1.5V vs. + 1.5 ~ after applying SCE potential
The period for applying the potential of + 2V vs. SCE for a short time may be 5 minutes to 6 hours.

Further, a method for preventing the attachment of living things based on the above-mentioned method for controlling aquatic living things will be described. In aquatic organism control methods, the control of aquatic organisms depends greatly on the environment in which they reside. That is, in an environment where the flow velocity is high, the sterilized organism is easily detached from the surface of the conductive composite layer 7 due to the resistance due to the flow velocity and the formation of the slime layer is prevented, but in an environment where seawater or fresh water is stagnant. Since there is no resistance due to the flow rate, the sterilized aquatic organisms adsorbed on the conductive composite layer 7 do not desorb. Therefore, it is preferable to employ a method in which a sterilized aquatic organism adsorbed on the surface of the conductive composite layer 7 is forcibly desorbed by applying a negative potential to the conductive composite layer. This principle focuses on the fact that aquatic organisms have a negative potential, and a process of adsorbing the aquatic organisms to the surface of the conductive composite layer 7 by applying a positive potential to sterilize the aquatic organisms, A step of applying a negative potential to remove the sterilized aquatic organisms adsorbed on the surface of the conductive composite layer 7 and periodically performing the step of preventing the formation of the slime layer even in various environments. It is. The positive potential may be the same as the above-described application condition.
The time for applying a positive potential of 1.5 V vs. SCE varies depending on the type and concentration of living organisms in water, or the flow rate and temperature, but is preferably about 5 minutes to 6 hours, and when the application time is longer than 6 hours. Since other aquatic organisms are adsorbed on the aquatic organisms sterilized on the base material and the aquatic organisms adsorbed later are not in direct contact with the conductive composite layer 7, electrochemical sterilization by positive potential is performed. Not affected.

Subsequently, when a negative potential is applied to the conductive composite layer 7, aquatic organisms adsorbed on the surface of the conductive composite layer 7 can be eliminated. The applied potential is -0 to -1.5V
vs. SCE, preferably -0.1 to 1.0 V vs.
SCE. If the applied potential is −0 V vs. SCE or higher, aquatic organisms cannot be detached from the surface of the structure, and if the applied potential is lower than −1.0 V vs. SCE, the pH increases, which is not preferable. The time for applying the negative potential varies depending on the type and amount of aquatic organisms adsorbed on the surface of the conductive composite layer 7, but is 30 seconds to 60 minutes, preferably 1 hour.
Minutes to 30 minutes. If the time is shorter than 30 seconds, the sterilized organism is not sufficiently detached, and when a positive potential is applied next, other organisms adhere to the sterilized organism. Also,
If the time is longer than 60 minutes, the liquid to be treated cannot be effectively sterilized.

In the present invention, the conductive composite layer 7 formed on the water contact surface of the underwater structure is used as a working electrode, and the conductive composite layer 7
An appropriate counter electrode for the working electrode should be installed so that it does not come into contact with the working electrode, and a potential can be applied using a DC power supply that can convert the polarity.Furthermore, when accurately applying a potential that does not cause electrolysis of seawater or freshwater In the above, a three-pole system in which a reference electrode is provided to control the potential between the reference electrode and the working electrode may be used, and a potential applied to the conductive composite layer may be controlled using a potentiostat as a DC power supply.

The underwater structures for applying the electrochemical biological control according to the present invention include electrodes for ships, ships' intake pipes, cooling seawater intake pipes, port facilities, and other underwater structures. Used.

[0023]

According to the present invention, an insulating resin film is bonded to the surface of a conductive substrate made of metal via an adhesive layer, and a conductive sheet material is bonded onto the insulating resin film via an adhesive layer. Since the conductive coating layer is formed on the conductive sheet, the insulating resin film completely insulates the base metal and the conductive composite layer consisting of the conductive sheet material and the conductive coating layer. No electrochemical adhesion or dissolution of the metal of the substrate occurs even when applied to the composite layer. In addition, the conductive composite layer including the conductive sheet material and the conductive coating layer has a lower resistance value than the conductive coating layer, and can prevent a decrease in potential due to the resistance value even at a location away from the potential application site. . Therefore, since a set potential can be applied to the surface of the underwater structure having a large area, the aquatic organisms attached to the entire surface of the underwater structure can be electrochemically controlled.

[0024]

The present invention will be specifically described below with reference to examples. <Preparation of a member for electrochemical biological control> Example 1 A polyester-based adhesive (PES360SK, manufactured by Toa Gosei Co., Ltd.) was applied to the surface of a stainless steel plate (30 × 50 × 1 mm).
5% by weight of an isocyanate-based curing agent (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added to the mixture, applied by a spray method, and dried at 100 ° C. for 5 minutes. Next, a 50 μm-thick polyester resin film (manufactured by Lintec Corporation) was laminated as an insulating resin film by thermocompression bonding.
Next, the polyester-based adhesive used for bonding the polyester resin film to the stainless steel substrate was coated on the polyester resin film under the same conditions, and dried. Next, a conductive sheet made of carbon fiber (Toray Industries, Inc.)
Manufactured by Torayca C06141) was laminated on the polyester resin film by thermocompression bonding. Next, the conductive resin composition shown below was coated by a spray method,
By drying for 0 minutes, a conductive coating layer was formed on the conductive sheet made of carbon fiber. The conductive composition is made of a urethane resin (Kansai Paint Co., Ltd.) as a binder resin.
10 μm with respect to the solid content of the urethane resin.
5% of graphite (Nippon Graphite Co., Ltd.) mixed with 30% by weight of 0.03 μm carbon black (Ketjen Black EC-600JD, manufactured by Mitsubishi Chemical Corporation)
0% by weight was blended and dispersed by a ball mill. still,
To the obtained conductive composition, 10% by weight of a dedicated curing agent was added before application by a spray method.

Example 2 The conductive sheet made of the carbon fiber used in Example 1 was used in an amount of 0.1%.
Other than changing to a conductive sheet made of 1 mm titanium wire,
A member made of a metal material was obtained in the same manner as in Example 1.

Comparative Example 1 The conductive sheet made of the carbon fiber used in Example 1 was directly bonded on the stainless steel plate used in Example 1 with the polyester adhesive used in Example 1.

<Evaluation of Durability> The members obtained in Examples 1 and 2 and Comparative Example 1 were evaluated for durability. The durability evaluation was performed using the apparatus shown in FIG. The test tank 8 is provided with members 9 (working electrodes) obtained from Examples and Comparative Examples, and the working electrodes are connected to a potentiostat 10. The potentiostat 10 is connected to the test tank 8.
Are connected to the reference electrode 11 and the counter electrode 12 disposed at the same position. Test tank 8 contains 500 ml of sterile seawater,
A stirring device 13 and a stirring rod 14 are arranged at the bottom. The reference electrode 11 was a saturated sweet potato electrode (SCE), and the counter electrode 12 was a platinum plate.

The potential was applied under the following conditions. (1)
1.2V vs. (2) 1.2 V vs. constant voltage of SCE. SCE60min / -0.6Vv
s. SCE for 10 minutes was applied alternately and continuously. The test period was performed continuously for 30 days. The back surface of the electrode (the surface where the metal was exposed) was covered and masked with a silicone resin (Konishi Corp. bus bond) before the test. After the test was completed, the resistance value between the metal substrate and the conductive coating layer was measured by a tester. Table 1 shows the results.

[0029]

[Table 1]

[0030]

According to the present invention, as shown in the results of the examples, the metal does not corrode even when a potential is applied, and the resistance between the metal and the conductive coating layer is infinite. Therefore, it has excellent stability over time, and since the conductive sheet material is bonded to the lower part of the conductive coating layer, the resistance value is low, and the area of ships, bay facilities, water distribution pipes, etc. It is useful for wide underwater structures.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross section of a member of the present invention.

FIG. 2 shows a test device for evaluating members obtained in Examples and Comparative Examples.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Conductive base material 2 Adhesive layer 3 Insulating resin film 4 Adhesive layer 5 Conductive sheet material 6 Conductive coating layer 7 Conductive composite layer 8 Test tank 9 Test members (members obtained in Examples and Comparative Examples,
Working electrode) 10 potentiostat 11 reference electrode 12 counter electrode 13 stirrer 14 stirring rod

Claims (1)

[Claims] 1. An insulating resin film is bonded to a surface of a conductive base material made of metal via an adhesive layer, and a conductive sheet material is bonded on the insulating resin film via an adhesive layer. An electrochemical biological control member having a conductive coating layer formed thereon.