JP6141654B2 - Anticorrosion structure and anticorrosion method - Google Patents

Description

  The present invention relates to an anticorrosion structure and an anticorrosion method for a steel material or the like having a reinforcing bar or a film covered with a concrete layer.

It is known that anti-corrosion is effective in reducing the corrosion of steel by reducing the potential of the steel to a potential that does not corrode by passing an electric current from the electrode (anode) installed near the surface of the concrete to the steel such as reinforcing steel in the concrete. It has been. As the anticorrosion, an external power supply method and a galvanic anode method are known.
The external power supply system is a cathodic protection that connects the positive electrode of the DC power supply device to the steel material that protects the auxiliary anode and the negative electrode with a conductor to create an electric circuit, and flows the anticorrosion current from the auxiliary anode to the steel material.
In the galvanic anode method, a material having a lower oxidation-reduction potential than the steel material subject to anticorrosion, for example, a galvanic anode (sacrificial anode) made of a base metal such as zinc, magnesium or aluminum or an alloy thereof is connected to the steel material by a conductor. The metal of the galvanic anode is ionized instead of the steel material to prevent corrosion of the steel material. That is, this is a method in which the battery is completed with a steel material to be anticorrosive as a cathode and a material having a lower oxidation-reduction potential than the steel material as an anode, and an anticorrosion current is caused to flow through the steel material by the potential difference between the two electrodes.

However, the galvanic anode method has a problem in that a periodic replacement of the galvanic anode is required because a substance having a low redox potential is consumed over time.
On the other hand, in the external power supply system, auxiliary anodes with high corrosion resistance such as titanium mesh, titanium grids, titanium rods, etc. are installed with grooves or holes in the concrete surface or surface and fixed with mortar. No replacement is necessary. However, the external power supply method requires a commercial power supply, but a structure such as a bridge that requires anticorrosion may not have a power supply nearby.
With respect to such a problem of securing a power supply, Patent Documents 1 to 3 propose an anticorrosion method of an external power supply system using a solar cell.

Patent Document 1 has a plurality of electrodes for anticorrosion arranged at a predetermined distance from a steel material to be protected in a concrete structure, and a power storage means is provided for the steel material to be protected and each electrode for anticorrosion. There has been proposed an anticorrosion device in which a provided solar cell is connected as a power source.
Patent Document 2 proposes an anticorrosion method for performing anticorrosion by supplying an anticorrosion current only intermittently from a power source configured as a solar cell power supply device that does not have a backup storage battery.
Further, Patent Document 3 proposes a method for catalyzing a reinforced concrete structure by intermittent energization using a solar cell with intermittent energization of 3 to 9 hours per day and an anticorrosion current density of ^{2 to} 50 mA / m ^2. Yes.

  Moreover, although it does not use the completed solar cell, as an anticorrosion method using solar light that does not require an external power supply, Patent Document 4 discloses that an electron generated in a semiconductor layer such as titanium oxide is collected to prevent corrosion. An anticorrosion structure has been proposed in which an electric current is supplied to provide an anticorrosion by moving to the body and having a circuit structure in which the moved electrons return to the semiconductor layer with ionic conductivity.

JP 2002-206182 A JP-A-7-286289 JP 2002-115085 A WO2012 / 008591

The proposal of Patent Document 1 uses a plurality of electrodes for cathodic protection, but the auxiliary anode having high corrosion resistance is expensive, which is disadvantageous in terms of cost. Moreover, since several electrodes are installed in the existing concrete structure, there exists a problem that construction takes time.
In particular, the work of installing multiple electrodes on an existing concrete structure is mainly on-site construction, and it is necessary to perform the work overhead in anticorrosion work where the back surface such as the bridge floor is often treated. Prone to heavy labor.
Furthermore, since the proposal of patent document 1 cannot arrange | position an electrode in the continuous planar shape, the movement of the positive electric charge by the electric current supplied from the positive electrode of a solar cell or a battery is carried out to rebar by ionic conduction in concrete. The energy barrier when changing to the movement of positive charge to transport is large. This barrier causes electrochemical polarization and prevents current from flowing. Therefore, it cannot be said that the electrode of Patent Document 1 is suitable for cathodic protection using a solar cell whose output varies greatly.

  The proposal of Patent Document 2 is an anticorrosion method for supplying an anticorrosion current without using a storage battery from a power source that can supply the anticorrosion current only intermittently, such as a solar battery. However, the object is limited to an anticorrosion object in which an electrolytic film is formed by hardness components such as calcium ions and magnesium ions in seawater and underground. Therefore, it is impossible to prevent corrosion of concrete structures and steel structures exposed in the air.

On the other hand, the proposal of Patent Document 3 is a corrosion prevention method in which the energization time per day and the energization current density at that time are in a certain range when intermittently energizing the reinforced concrete structure using an external power source.
In the proposal of Patent Document 3, it is preferable from the viewpoint of economy that a solar power source is used as the main power source of the external power source. However, because there are cases where the predetermined energization time and the anticorrosion current density cannot be maintained due to external factors such as season and weather and the number of energizations per day, the predetermined energization time and the auxiliary power source such as a storage battery can be maintained. It is described that the anticorrosion current density at that time is maintained.
Patent Document 3 does not specifically describe a detection method when the predetermined energization time and the anticorrosion current density at that time cannot be maintained, a maintenance method using an auxiliary power source in that case, and the like. Therefore, although the proposal of patent document 3 suggests the possibility of corrosion prevention by intermittent electricity supply, it does not disclose the corrosion prevention by a solar cell.

And the anticorrosion structure of patent document 4 is a semiconductor layer-electrically conductive layer-circuit wiring-corrosion body by the electric charge movement path | route, and a semiconductor layer-second electrolyte layer-first electrolyte layer-concrete layer. -It consists of the movement path | route of the electric charge by ionic conductivity called a to-be-protected object.
In this invention, since the electron supply sheet can be fixed to the concrete layer using the first electrolyte layer, the construction is easy.

In the present invention, a closed circuit is formed by using a conductive layer as a working electrode of a dye-sensitized solar cell (DSC) and using an anticorrosive body as a counter electrode.
Therefore, the conductive layer is an electron supply sheet that collects electrons generated in the semiconductor layer and supplies the electrons to the object to be protected, and is connected to the object to be protected.
And since a cation is reduce | restored by an electron in a to-be-protected body, it connects electrically and becomes DSC of a closed circuit. Thereby, even if it is a case where the electron production amount of a semiconductor layer is small, an electric current can be sent through a to-be-protected body and a potential can be made into a base.
However, when the anticorrosion circuit is formed, the power generation layer has a single cell structure, the generated voltage is low, and the amount of generated current is small, so that it may not be applicable to a corroded reinforcing bar.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the anticorrosion structure and the anticorrosion method which significantly reduced the work amount of anode installation in a construction site, and used the solar cell for the power supply.

  The inventors of the present invention, as a result of intensive studies to solve the above-described problems, have come up with the idea of using an electrolyte layer formed into a sheet shape having an adhesive force that can be attached to the surface of the corrosion-protected body. For example, a sheet of a gel electrolyte such as a conductive hydrogel (hereinafter sometimes referred to as “hydrogel”) is conductive by ions contained in a gel solvent (water in the case of hydrogel) that is more abundant than concrete. Electrochemical polarization at the interface with the layer can be reduced. In addition, the auxiliary anode can be adhered to the concrete surface by the adhesiveness of the resin matrix constituting the gel electrolyte. Thereby, since the adhesiveness of a gel electrolyte and a concrete layer becomes high, ion conduction tends to occur. In addition, the amount of work at the construction site can be reduced when the auxiliary anode is installed. The inventors of the present invention have obtained these findings and completed the present invention.

The present invention provides the following anticorrosion structure.
(1) On one surface of a conductive layer formed into a sheet shape, an electrolyte was formed into a sheet shape, and a gel electrolyte layer having an adhesive force capable of being attached to the conductive layer and the surface layer of the corrosion-protected body was attached. An auxiliary anode is attached to the surface layer of the object to be protected using the gel electrolyte layer, the conductive layer of the auxiliary anode is connected to a positive electrode of a power circuit including a solar cell, and the negative electrode of the power circuit is covered. An anticorrosion structure characterized by being connected to an anticorrosion body.
(2) The anticorrosion structure according to (1), wherein the conductive layer contains a carbon material.
(3) The anticorrosion structure according to (2), wherein a carbon material is supported on a fiber substrate or a film substrate.
(4) The anticorrosion structure according to (3), wherein the carbon material is carbon powder.
(5) The anticorrosion structure according to any one of (1) to (4), wherein the conductive layer has a large number of communication holes through which gas can permeate.
(6) The anticorrosion structure according to any one of (1) to (5), wherein an outer surface of the conductive layer is covered with a protective layer.

Moreover, this invention provides the following anticorrosion methods.
(7) The auxiliary anode having the anticorrosion structure according to any one of (1) to (6) is attached to a concrete structure using the gel electrolyte layer, and the conductive layer of the auxiliary anode includes a solar cell. An anticorrosion method comprising: connecting to a positive electrode of a power supply circuit; and supplying a current by connecting the negative electrode of the power supply circuit to an anticorrosive body embedded in a concrete structure.
(8) The anticorrosion method according to (7), wherein a current is supplied to the subject to be protected without using a secondary battery as a power storage means.
(9) The anticorrosion method according to (8), wherein the solar cell is operated without performing maximum power point tracking.

According to the anticorrosion structure of (1), the electrolyte is formed into a sheet shape, and the electrolyte layer having an adhesive force that can be attached to the surface layer of the conductive layer and the corrosion-protected body is attached to one surface of the conductive layer, Since it has a laminated structure, the auxiliary anode can be easily attached only to the surface layer of the body to be protected using the surface of the electrolyte layer without the conductive layer attached without embedding the auxiliary anode with mortar. Can be installed. Thereby, the work amount in the construction site for installing an auxiliary anode can be reduced significantly.
In addition, the conductive layer formed into a sheet shape and the gel electrolyte formed into a sheet shape are in close contact with each other over a wide area. In addition, the abundance of gel electrolyte ions compared to concrete efficiently converts the charge transfer from the solar cell to the ionic conduction of the electrolyte. As a result, electrochemical polarization can be reduced. And the surface of the to-be-prevented body and the gel electrolyte formed into a sheet form are in close contact with each other over a wide area, so that the potential distribution of the surface layer of the to-be-prevented body becomes uniform when performing anti-corrosion. As a result, even if the voltage applied to the auxiliary anode is set low in order to use the solar cell, current flows easily, and thus corrosion protection using the solar cell is possible.

According to the anticorrosion structure of (2), in addition to the effect of the anticorrosion structure of (1), it is not necessary to use an expensive metal such as titanium for the auxiliary anode, which is advantageous in terms of cost. Further, since the carbon material is lighter than the metal, the auxiliary anode can be lightened.
According to the anticorrosion structure of (3), in addition to the effect of the anticorrosion structure of (2), a carbon material can be supported on the base material of the synthetic resin, so that the corrosion resistance is high, the conductivity is adjusted, and the cost is reduced. Is possible.
According to the anticorrosion structure of (4), in addition to the effect of the anticorrosion structure of (3), an inexpensive carbon powder can be used, which is advantageous in terms of cost.
According to the anticorrosion structure of (5), in addition to the effects of the anticorrosion structure of (1) to (4), the conductive layer has a large number of communication holes through which gas can permeate. In this case, the gas generated at the interface with the electrolyte layer can be released. Thereby, it can prevent that a conductive layer partially peels from an electrolyte layer. Therefore, as a first step, a large current flows, for example, by adding a power source such as a commercial power source, a primary battery such as a dry battery or a fuel cell, or a secondary battery having a power storage function, to a reinforcing bar that is undergoing corrosion. When a passive film is formed by applying a voltage to suppress the progress of deterioration, as a second step, use a solar cell to apply a voltage that generates less gas due to water or chloride electrolysis to prevent corrosion. Is possible.
According to the anticorrosion structure of (6), in addition to the effects of the anticorrosion structure of (1) to (5), physical damage to the conductive layer or the electrolyte layer without reducing the handleability and workability of the auxiliary anode, Invasion of dirt, rain, and incoming salt can be prevented.

According to the anticorrosion method of (7), the same effect as the anticorrosion structure of (1)-(6) is acquired.
According to the anticorrosion method of (8), maintenance management of power storage means such as a secondary battery becomes unnecessary. In addition, since a circuit and a charging circuit for preventing overcharge and overdischarge are not required, the power supply circuit is simplified.
According to the anticorrosion method of (9), a circuit for tracking the maximum power point becomes unnecessary, and the power supply circuit is simplified.

It is sectional drawing which shows typically an example of the anticorrosion structure of this invention. It is explanatory drawing which shows an example of the power supply circuit used for the anticorrosion structure of this invention. It is a graph which shows the generated current density of the confirmation experiment of the anticorrosion effect by intermittent energization. It is a graph which shows the reinforcing bar electric potential of the confirmation experiment of the anticorrosion effect by intermittent electricity supply. It is a graph which shows the generated voltage in Example 1 of the anticorrosion structure of this invention. It is a graph which shows the generated electric current amount in Example 1 of the anticorrosion structure of this invention. It is a graph which shows the reinforcing bar electric potential in Example 1 of the anticorrosion structure of this invention. It is the elements on larger scale of the graph which shows the generated voltage in Example 1 of the anticorrosion structure of this invention. It is the elements on larger scale of the graph which shows the generated electric current amount in Example 1 of the anticorrosion structure of this invention. It is the elements on larger scale of the graph which shows the reinforcing bar electric potential in Example 1 of the anticorrosion structure of this invention. It is explanatory drawing which shows another example of the power supply circuit used for the anticorrosion structure of this invention. It is a graph which shows the generated voltage in Example 2 of the anticorrosion structure of this invention. It is a graph which shows the generated electric current amount in Example 2 of the anticorrosion structure of this invention. It is a graph which shows the reinforcement potential in Example 2 of the anticorrosion structure of the present invention. It is the elements on larger scale of the graph which shows the generated voltage in Example 2 of the anticorrosion structure of this invention. It is the elements on larger scale of the graph which shows the generated electric current amount in Example 2 of the anticorrosion structure of this invention. It is the elements on larger scale of the graph which shows the reinforcing bar electric potential in Example 2 of the anticorrosion structure of this invention.

The present invention will be described below based on preferred embodiments with reference to the drawings.
FIG. 1 schematically shows a first embodiment of an example of the anticorrosion structure of the present invention.
In the anticorrosion structure 1 of this embodiment, the auxiliary anode 10 is installed by sticking the electrolyte layer 12 to the surface of the concrete layer 3. Then, the positive electrode 55 of the power supply circuit 5 including the solar cell is connected to the conductive layer 11 of the auxiliary anode 10 using the circuit wiring 6, and the negative electrode 56 of the power supply circuit 5 is connected to the corrosion-protected body 4 using the circuit wiring 6. Thus, the anticorrosion structure 1 of the present invention is formed.
In addition, "sticking" means that objects are integrated by adhesion or adhesion. Adhesion means that objects can be peeled off at an intentional interface, but the objects are integrated with an adhesive strength that does not peel off in a natural state. Adhesion means that the objects are integrated with an adhesive strength that does not allow separation at the interface.

An example of the power supply circuit 5 used in this embodiment is shown in FIG. As the solar cell 51 used in this embodiment, a crystalline solar cell, an amorphous solar cell, a compound solar cell such as GaAs or CIS, a dye-sensitized solar cell, an organic thin film solar cell, A junction type solar cell or the like can be used. These solar cells may be single cells, but are preferably modularized or arrayed by connecting a plurality of cells.
The solar battery 51 may be used in combination with a power storage means such as a secondary battery or a capacitor (capacitor) in order to back up a state where power generation is impossible at night or due to bad weather.

  When a secondary battery is used as the power storage means, a solar battery having a nominal maximum output operating voltage (Vpm) equal to or higher than a voltage capable of charging the secondary battery is preferable. In this case, since the output voltage of the solar cell 51 may be fixed to a voltage that can charge the secondary battery, the maximum power point tracking (MPPT: Maximum Power) that controls the solar cell to always operate at the maximum power point is possible. Point tracking is preferable because the power generation capacity of the solar cell can be effectively utilized. When using a solar battery that may not be able to obtain an output voltage higher than the voltage that can charge a secondary battery, etc., the maximum operating voltage is stored in a capacitor that is larger than the charge voltage of the secondary battery, resulting in a pulsed current. By rectifying, the secondary battery can be charged. Alternatively, the secondary battery may be charged by boosting with a circuit such as various DC-DC converters.

It is presumed that the name “battery” is attached, but a solar battery is easily misunderstood as generating a constant voltage or current like a primary battery when exposed to light. Therefore, for example, an anticorrosion invention in which actual verification is not performed can be born simply by adopting a solar cell as an external power source, such as the anticorrosion device described in Patent Document 1. However, when it is actually applied to cathodic protection, as shown in FIG. As for the current, the amount of current generated in the daytime varies as shown in FIG.
With respect to the voltage, the charge generated by the solar battery is stored in the secondary battery, and the secondary battery is used as the anticorrosion power source, so that the anticorrosion by the constant voltage can be easily performed. Furthermore, when performing anticorrosion by a constant current, it may be converted to a constant current by a constant current circuit or a constant current diode. Or you may convert into alternating current with an inverter and may utilize the commercially available constant current power supply for corrosion prevention.
Therefore, when the secondary battery is used as the main power source for corrosion prevention, the output voltage of the solar cell 51 is not important, and only the output current amount of the solar cell 51 needs to be considered.
When a secondary battery is used as the power storage means, control of voltage and current becomes easy, but maintenance of the secondary battery is required. Further, since a circuit for preventing overcharge and overdischarge is required, the power supply circuit 5 becomes complicated.

In the case of corrosion prevention by always energizing, the current density necessary for the anticorrosion by the external power supply method is about 1 to 30 mA / m ² . Therefore, the maximum output operating current (Ipm) of the solar cell 51 when always energized depends on the area to be protected, the circuit configuration, and the environment, but is necessary for corrosion protection assuming that power generation at night is completely impossible. It is preferable to obtain a current density of 300 mA / m ² or more, which is about 10 times the upper limit of the current density.
Patent Documents 2 and 3 suggest the possibility of cathodic protection by intermittent energization. The amount of current generated by the solar cell 51 in the case of intermittent energization may be small. However, in consideration of safety, 60 mA / m ² or more, which is about twice the upper limit of the current density required for cathodic protection by the external power supply method, is obtained. It is preferable that

By the way, as described in paragraph 0020 of Patent Document 2, conventionally, anticorrosion using a solar cell as a power source has been considered to increase the potential of the anticorrosion object during the daytime when the weather is bad, as in the nighttime.
However, in the present invention, it can be seen from FIG. 7 and FIG. 14 that there was no day when the potential of the reinforcing bars did not drop, although there were days when the weather was not good. The reason for this is that cathodic protection requires a small current density, and the auxiliary anode of the present invention has an abundance of gel electrolyte ions compared to concrete, so that the transfer of charge from the solar cell is responsible for the ionic conduction of the electrolyte. This is thought to be because of efficient conversion.
Therefore, in the present invention, it can be understood that the fluctuation of the generated current amount due to bad weather is not an important factor.

A large capacitor such as an aluminum electrolytic capacitor or an electric double layer capacitor can be used without using a secondary battery as the power storage means. In this case, in order to make the voltage and current constant, a dedicated circuit, a constant voltage diode, and the like are required, but maintenance and management are easy. In addition, since a circuit for preventing overcharge and overdischarge can be eliminated, the power supply circuit 5 can be simplified. Depending on the capacity of the capacitor, intermittent energization may occur, but corrosion protection is possible even with intermittent energization as will be described later.
As the solar cell 51 used in this case, it is preferable that a generated voltage of about 0.3 V to 5 V is obtained.
Even if the generated voltage of the solar cell 51 is larger than this range, the circuit can be adjusted. If the applied voltage is too large without adjustment by the circuit, the moisture in the concrete is electrolyzed and hydrogen is generated, hydrogen fragility occurs in the to-be-corroded objects such as reinforcing bars, and the moisture in the electrolyte layer 12 is electrolyzed. And may dissipate. Even if the voltage generated by the solar cell 51 is smaller than this range, the voltage can be adjusted by the booster circuit, but the current density required for anticorrosion may not be obtained.
In the present invention, the auxiliary anode 10 to which the electrolyte layer 12 is attached is attached to the surface of the object 4 to be protected, so that current flows easily and a sufficient anticorrosion current can be obtained with a low generated voltage. It is.

In the present embodiment, as shown in FIG. 2, the power supply circuit 5 includes a diode 52 connected in series between the solar cell 51 and the auxiliary anode 10 in order to prevent a corrosion current from flowing through the body 4 to be protected at night. Connect to. The diode 52 is preferably a semiconductor element having a rectifying function such as a PN diode. Further, when the generated voltage of the solar cell 51 is high, it is preferable to limit the voltage using a step-down circuit, a Zener diode, or the like.
Further, a capacitor 53 is connected in parallel with the solar cell 51 between the diode 52 and the auxiliary anode 10. The capacitor 53 is for storing electricity by the solar cell 51 in the daytime and for passing a current through the corrosion-protected body 4 by the electric charge stored at nighttime. As the capacitor, an electrolytic capacitor, an electric double layer capacitor, or the like that can easily obtain a large capacity is preferable.
And in order to monitor the electric current between the to-be-protected object 4 and the auxiliary | assistant anode 10, the resistance 54 is connected in series between the solar cell 51 and the to-be-protected object 4, and the both ends of the resistance 54 are connected by the voltmeter 57. Measure voltage and check current. The current may be measured directly by connecting a non-resistance ammeter in series. Further, as shown in FIG. 2, a voltmeter 58 is provided so that a voltage ignoring a voltage drop due to the diode 52 between the positive electrode 55 and the negative electrode 56 of the solar cell 51 (generated voltage applied to the corrosion-protected body 4) can be measured. It is preferable to keep it.

The conductive layer 11 is a planar electrode that uniformly supplies the current supplied from the power supply circuit 5 to the surface of the electrolyte layer 12, and has durability (corrosion resistance) against gases such as oxygen and chlorine generated during energization and an electrolyte solution. ) Is formed into a sheet shape.
Examples of the material having high corrosion resistance used for the conductive layer 11 include metals such as platinum, titanium, nickel, lead and stainless steel, and carbon materials.
Among metals having high corrosion resistance, titanium and stainless steel are preferable because they are excellent in corrosion resistance. Titanium is particularly preferable because it is light and soft. Stainless steel is preferable because of its cost advantage. Titanium and stainless steel are more preferable when platinum or ruthenium is plated because they are excellent in corrosion resistance and conductivity.

When a metal is used for the conductive layer 11, a metal foil, a metal ribbon with or without an opening, a metal mesh such as a metal fiber woven fabric or an expanded metal, or the like formed into a sheet shape can be used. A metal ribbon or metal mesh having an opening is light and low in cost, but may have poor adhesion strength with the electrolyte layer 12. Therefore, the metal used for the conductive layer 11 is preferably a metal foil.
When using metal foil, the thickness is arbitrary. It may be determined in consideration of availability, rigidity, weight, cost, and the like. For example, when a titanium foil is used, it is preferably in the range of 20 μm to 500 μm. When using stainless steel foil, it is preferable to set it as the range of 10 micrometers-300 micrometers. If it is thicker than this range, the conductive layer becomes too heavy, and there is a possibility of peeling from the electrolyte layer 12 during long-term use. In addition, it is difficult to process due to its high rigidity.
In the case of using a metal ribbon, a plurality of sheets can be used side by side in order to widen the width. In this case, it is preferable to electrically connect the metal ribbons with a conductor.

Among the materials having high corrosion resistance used for the conductive layer 11, a carbon material is light and easy to impart flexibility, and it is preferable because adjustment can ensure both conductivity and cost reduction.
In the case where a carbon material is used for the conductive layer 11, a sheet made of a carbon material having conductivity such as a graphite sheet obtained by processing graphite into a sheet, a carbon fiber woven fabric obtained by carbonizing organic fibers, a nonwoven fabric, a knitted fabric, etc. Carbon-based paper, film base, woven fabric, non-woven fabric, knitted fabric, paper, and other sheet-like fiber base materials are coated and / or impregnated with conductive carbon materials such as carbon short fibers and carbon powder. Carbon-containing sheets can be used. In the carbon fiber sheet, some of the fibers may not be carbon fibers.

  Here, the application and / or impregnation includes application and impregnation and application and impregnation. The application means that the carbon material is mainly attached to the surface of the base material, and the impregnation means that the carbon material is attached to the surface of the base material and penetrates into the inside. There is no need to interpret them strictly. In short, it is only necessary that the carbon material adheres to the substrate at least on its surface with a practically sufficient degree of separation, and the carbon material does not necessarily penetrate into the substrate. However, in the case of a fiber base material, since the conductivity of the conductive layer 11 is increased, it is preferable that the carbon material penetrates into the gaps of the fiber base material. Hereinafter, it may be expressed as “application” including impregnation.

It is preferable to use a carbon-containing sheet coated with a carbon material as the conductive layer 11 because it is advantageous in terms of cost and easy adjustment of conductivity.
Metal, carbon material, synthetic resin, glass, cotton, hemp, wool, silk, etc. can be used as the material of the film substrate or fiber substrate carrying the carbon material of the carbon-containing sheet.
Among these, a base material made of a metal is preferable because it is excellent in conductivity, but it may be corroded by a gas such as oxygen or chlorine generated during energization and an electrolyte solution (electrolytic solution). For this reason, it is necessary to use platinum, titanium, etc. with high corrosion resistance, and it is disadvantageous in cost. Therefore, it is preferable that the carbon-containing sheet has a high corrosion resistance when a carbon material is supported on a synthetic resin base material, because the conductivity can be adjusted and the cost can be reduced.

  A conductive layer made of a carbon-containing sheet in which a carbon material is applied to a fiber base (hereinafter sometimes referred to as “fiber conductive layer”) is a contact area between the conductive layer 11 and the electrolyte layer 12 due to unevenness on the surface of the fiber base. Is preferable. And when the gel electrolyte layer which has adhesiveness in the electrolyte layer 12, and is flexible and excellent in the followability to unevenness | corrugation is used, a part of gel permeates into the clearance gap between fiber base materials, and adhesiveness increases. Thereby, the gel electrolyte can efficiently ionize and receive positive charges sent from the positive electrode of the power supply circuit 5, and can be efficiently transferred to the surface layer 3 of the corrosion-protected body 4 by ion conduction. Also, by applying a carbon material so that the gap between the fiber bases becomes a communication hole that allows gas to pass through, the gas generated when a large current is used during corrosion prevention is released from the gap between the fiber bases. Can do.

As the fiber base material of the fiber conductive layer, conductive fibers such as metal fibers and carbon fibers, and non-conductive fibers such as glass fibers, animal fibers, vegetable fibers, synthetic resin fibers, woven fabrics, nonwoven fabrics, A fiber base material processed into a sheet such as knitted fabric or paper can be used. A plurality of these fiber base materials may be used in combination, including the combined use of conductive fibers and non-conductive fiber base materials.
Although the fiber base material which consists of metal fibers is excellent in electroconductivity, it may corrode over time with generation | occurrence | production of electrolyte solution or gas. In such a case, it is preferable to apply a carbon material having excellent corrosion resistance. In this case, since the whole fiber conductive layer becomes conductive, the conductivity is high.
Of the fiber base materials of the fiber conductive layer, a fiber base material made of synthetic resin fibers is preferable because of its high corrosion resistance.

  Examples of the resin constituting the synthetic resin fiber serving as a fiber base material include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polytetrafluoroethylene (PTFE) and ethylene-tetrafluoroethylene copolymer (ETFE). ) And other fluorine resins: acrylic resins; polyolefin resins such as polyethylene (PE) and polypropylene (PP); polyamide resins such as nylon, tetraacetyl cellulose (TAC); polyester sulfone (PES); polyphenylene sulfide (PPS); Polycarbonate (PC); Polyarylate (PAr); Polysulfone (PSF); Polyetherimide (PEI); Polyacetal; Polyimide polymer; Polyethersulfone and the like can be mentioned.

A conductive layer made of a carbon-containing sheet obtained by applying a carbon material to a film substrate (hereinafter sometimes referred to as “film conductive layer”) is preferable because the amount of the carbon material applied can be accurately controlled. Moreover, since a carbon material does not permeate | transmit the back side of a film, it can apply | coat with a general purpose simple coating apparatus.
However, if the substrate is a film, it may be difficult to apply the carbon material thickly. In such a case, a carbon material may be applied to both sides of the film. In this case, it is preferable to make the carbon coating layers on the front and back conductive by making the film porous or connecting the front and back with a conductive tape. Moreover, a carbon base material may be embed | buried in a carbon coating layer and a carbon coating layer may be reinforced.

  Depending on the film substrate, the film conductive layer may be difficult to transmit gas. Usually, when a small voltage of 2 V or less is applied at the time of anticorrosion, the amount of gas generated is extremely small, and the generated gas permeates the film base material, which is not a problem. However, when the amount of current that can be desalted or realkalized is required to prevent corrosion of reinforcing steel bars, it is generated by providing a large number of through holes 15 in the film conductive layer. Gas can escape. In this case, the inner diameter of the through hole 15 is preferably as small as possible if gas can be transmitted. However, since both the base film and the carbon coating layer are perforated, it is preferable to have a size of, for example, about 0.1 to 1 mm so as not to be clogged. Further, when the thickness of the carbon coating layer is large, it is preferable that the diameter of the through hole 15 is also relatively large.

For forming the through hole 15, a known method such as punching, laser beam, drilling using a hot needle or a cold needle can be employed. Punching with a punch provides a hole having a relatively large diameter as compared with drilling using a hot needle or a cold needle. Perforation using a cold needle is in a state where the periphery of the hole is irregularly cleaved, and it is difficult to form a clear hole, but gas permeation is possible. Melt drilling using a laser beam or a hot needle is preferable because the peripheral edge of the hole is melted and solidified to form a clear hole, and even if the hole is provided with a high density, the strength of the conductive layer 11 is relatively small.
The shape of the through hole 15 can be a circle, an ellipse, a square, a rectangle, a polygon, an indeterminate shape, or any other shape.

As the film substrate used for the film conductive layer, a resin film is preferable because it has excellent corrosion resistance and can be easily formed into a film. As resin which forms a resin film, resin similar to resin which comprises the fiber base material mentioned above can be mentioned.
The thickness of the film substrate used for the film conductive layer is not limited as long as the physical strength is ensured, but can usually be about 10 μm to 100 μm.

The carbon material applied to the substrate of the fiber conductive layer and the film conductive layer is preferably carbon powder made of conductive carbon.
Examples of the conductive carbon include graphite; various carbon blacks such as ketjen black, thermal black, acetylene black, channel black, and furnace black; carbon nanotubes and the like. Of these, graphite, ketjen black and carbon nanotubes are preferred because of their high conductivity. In particular, graphite that is inexpensive and has high conductivity is preferable.
The carbon powder may contain short carbon fibers.
By using a carbon material as the conductive particles, it is cheaper than when noble metals such as platinum and gold are used for the conductive particles, and chemically compared to when using base metals such as nickel and zinc for the conductive particles. Excellent stability. Thereby, durability with respect to corrosion with time accompanying the electrolyte solution of the conductive layer 11 made of a fiber conductive layer or a film conductive layer and the generation of current can be increased.

  As a method of applying a carbon material to a fiber base material or a film base material, for example, carbon powder or carbon short fibers are dispersed in a solvent such as an organic solvent or water to make a paste, and the obtained carbon paste is For example, the method of apply | coating and drying by coating methods, such as immersion, a gravure coat, a bar coat, a screen coat, is mentioned. In the carbon paste, additives such as a dispersant may be blended in order to improve the dispersibility of the carbon material. Moreover, in order to make application | coating and formation of a layer easy in carbon paste, the resin component may be mix | blended as a binder. The larger the amount of the binder added, the better for the formation of the layer, but there are cases where the binder remains in the conductive layer 11 when the solvent volatilizes and inhibits contact between the conductive particles. Therefore, it is preferable that the carbon paste contains a binder in consideration of conductivity.

The electrolyte layer 12 is a charge transfer layer solidified in a sheet shape containing ions having positive and negative charges. Ions contained in the electrolyte layer 12 move, or charges move between these ions to move charges by ionic conduction. The main electrolyte used for the electrolyte layer 12 is an ionic liquid composed of a gel electrolyte in which an electrolyte solution is held in a resin matrix, a cation such as imidazolium ion or pyridinium ion, and an anion such as BF ₄ ⁻ or PF ₆ ^−. Examples include polymer electrolytes such as intrinsic polymer electrolytes in which lithium salts such as bis (trifluoromethanesulfonyl) imide lithium (LiTFSI) are held in ion gels or polyether resins in which (organic room temperature molten salt) is held in a resin matrix Can do.
Among these, the gel electrolyte is preferable because it has high ionic conductivity and easily imparts flexibility. Gel electrolyte is polymer addition, oil gelling agent addition, polymerization including polyfunctional monomers,
An electrolyte is gelled (solidified) in a resin matrix by a polymer crosslinking reaction or the like.

The electrolyte layer 12 has an auxiliary anode 10 attached to the ion-permeable surface layer 3 existing on the surface of the object 4 to be protected, such as a concrete layer or a paint film, and is supplied from the positive electrode 55 of the power supply circuit 5 to the conductive layer 11. It is a layer that converts the movement of electrons (electron conduction) by the generated current to ion conduction and transfers charges to the surface layer 3 of the to-be-protected body 4. When the electrolyte layer 12 is a gel electrolyte that is a flexible pressure-sensitive adhesive layer, when the auxiliary anode 10 is attached to the surface layer of the body 4 to be protected, for example, the concrete layer 3, the electrolyte layer is formed on the minute irregularities of the concrete layer 3. Is preferable because the electrolyte layer can be brought into contact and stuck with a high adhesive strength and a wide contact area.
The thickness of the gel electrolyte layer used for the electrolyte layer 12 is not particularly limited, but is preferably 100 μm to 1000 μm. Although there is no particular problem if the electrolyte layer 12 is thicker than this range, it is disadvantageous in terms of cost. If the electrolyte layer 12 is thinner than this range, when the electrolyte solution in the gel electrolyte is absorbed by the concrete layer 3, the charge transfer capability may be lowered.

The gel electrolyte used for the electrolyte layer 12 is a conductive material having adhesiveness in which a solvent and an electrolyte salt, preferably a wetting agent are held in a resin matrix obtained by copolymerizing a polymerizable monomer with a crosslinkable monomer. The polymer gel electrolyte is preferable. The polymer gel electrolyte needs to be able to maintain a shape by holding a liquid solvent or the like in a three-dimensional network structure of polymer chains in which polymer chains are physically or chemically bonded.
The polymer gel electrolyte used for the electrolyte layer 12 can form a flexible polymer three-dimensional network structure (resin matrix) by appropriately designing the polymer three-dimensional network structure. Since the polymer gel electrolyte having such a skeleton has an appropriate cohesive force and good wettability to the adherend surface, the contact portion with the adherend can be approached at the molecular level. Moreover, since the compressive strength and the tensile strength are imparted to the gel by an appropriate cohesive force of the polymer gel electrolyte, high adhesiveness can be obtained by the mutual intermolecular force.
The resin matrix of the polymer gel electrolyte used for the electrolyte layer 12 is subjected to a crosslinking treatment with a crosslinking agent in order to increase cohesion, or a polymerization monomer and a crosslinking monomer are polymerized to be crosslinked. It is preferable to keep it. A resin matrix in which polymer chains are three-dimensionally cross-linked is excellent in the ability to retain a solvent and a wetting agent. Thereby, it is possible to hold | maintain the electrolyte salt in the resin matrix in the state melt | dissolved in the molecular level.

  The polymerizable monomer that forms the resin matrix is not particularly limited as long as it is a monomer having one polymerizable carbon-carbon double bond in the molecule. For example, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, (poly) ethylene glycol (meth) acrylate, (poly) propylene glycol (meth) acrylate, (poly) glycerin (meth) acrylate, etc. (Meth) acrylic acid derivatives; (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-butyl (meth) acrylamide, N, N-dimethyl ( (Meth) acrylamide, diacetone acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, (meth) acrylamide derivatives such as t-butylacrylamide sulfonic acid and their salts; N-vinylpyrrolidone, N-vinylformamide, N-vinylacetoa N- vinylamide derivatives such as de, vinyl sulfonic acid, and sulfonic acid monomers such as allyl sulfonic acid and salts thereof. In addition, (meth) acryl means acryl or methacryl.

  As the crosslinkable monomer that is polymerized and cross-linked with the polymerizable monomer, it is preferable to use a monomer having two or more double bonds having a polymerizable property in the molecule. Specifically, polyfunctional (meth) acrylamide monomers such as methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, N, N-methylenebisacrylamide, N-methylolacrylamide; (poly) ethylene glycol di ( Polyfunctional (meth) acrylate monomers such as (meth) acrylate, (poly) propylene glycol di (meth) acrylate, glycerin di (meth) acrylate, glycerin tri (meth) acrylate, glycidyl (meth) acrylate; tetraallyloxy Ethane; diallylammonium chloride and the like. Of these, polyfunctional (meth) acrylamide monomers are preferred, and N, N-methylenebisacrylamide is more preferred. In addition, these crosslinkable monomers may be used independently and 2 or more types may be used together.

The content of the crosslinkable monomer is preferably 0.005 to 10 parts by weight with respect to 100 parts by weight of the resin matrix obtained by polymerizing and crosslinking the polymerizable monomer and the crosslinkable monomer. When the content of the crosslinkable monomer in the resin matrix is small, there are few network crosslinking points connecting the main chains, and a polymer gel electrolyte excellent in shape retention may not be obtained. If the content of the crosslinkable monomer is large, the network cross-linking points connecting the main chains will increase, and a polymer gel electrolyte with high apparent shape retention will be obtained, but the polymer gel electrolyte will become brittle and will have a tensile force. In some cases, the polymer gel electrolyte is likely to be cut or broken due to the compression force. In addition, the polymer main chain becomes hydrophobic due to an increase in the number of cross-linking points, making it difficult to stably hold the solvent encapsulated in the network structure, and bleeding may easily occur.
In order to increase the ability to retain the solvent and wetting agent and the cohesive force of the polymer gel electrolyte, a prepolymerized resin matrix is newly impregnated with a polymerizable monomer and a crosslinkable monomer, and polymerized again. You may form the three-dimensional structure which mutually penetrated different resin matrices. The prepolymerized resin matrix may or may not be cross-linked.

The solvent that can be used for the polymer gel electrolyte is preferably a polar solvent having a high boiling point, a low vapor pressure at room temperature, and compatibility with the polymerizable monomer and the crosslinkable monomer.
Examples of such solvents include water, alcohols such as methanol, ethanol and isopropanol, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, N, N-dimethylformamide, N, N-dimethylacetamide, N, N′-. Examples thereof include amides such as dimethyl-2-imidazolidinone and N-methyl-2-pyrrolidone, sulfolane and dimethyl sulfoxide. These solvent components may be used as a mixture.
The solvent contained in the polymer gel electrolyte is preferably 5 to 50% by weight, more preferably 5 to 40% by weight. If it is less than this range, the flexibility of the polymer gel electrolyte is low, and an electrolyte salt can hardly be added, so that good conductivity cannot be obtained. In addition, exceeding this range greatly exceeds the equilibrium solvent retention amount of the polymer gel electrolyte, which may cause bleeding of the solvent. In addition, a solvent that cannot be retained flows out, and the change in physical properties over time may increase.

The polymer gel electrolyte used for the electrolyte layer 12 is a hydrogel in which water and an electrolyte salt, preferably a wetting agent are retained in a hydrophilic resin matrix, and the moisture and solvent in the concrete layer 3 Is common. Therefore, ion conduction is likely to occur at the interface between the concrete layer 3 and the electrolyte layer 12, which is preferable.
The hydrogel can hold the electrolyte salt dissolved in water at the molecular level in the resin matrix. In addition, the aqueous electrolyte solution has a high charge transfer speed and can easily impart flexibility and adhesiveness.
The water content of the hydrogel used for the electrolyte layer 12 is usually 5 to 50% by weight, preferably 10 to 30% by weight. When the water content is low, the flexibility of the hydrogel may be reduced. Moreover, ion conductivity may fall and it may be inferior to the capability to move an electric charge. When the water content of the hydrogel is high, the water exceeding the water content that can be retained by the hydrogel may be detached or dried to cause the gel to shrink or the change in physical properties such as ion conductivity may increase. Moreover, it may be too flexible and inferior in shape retention.

  When a wetting agent is included in the hydrogel used for the electrolyte layer 12, a decrease in the water content of the hydrogel can be suppressed. It is preferable to adjust the wetting agent to a range of about 5 to 80% by weight, preferably about 20 to 70% by weight from the viewpoint of adhesiveness and shape retention. If the content of the wetting agent in the hydrogel is low, the moisture retention capacity of the hydrogel will be poor, the moisture will easily evaporate, the hydrogel will not be stable over time, and the flexibility will be poor and the adhesiveness will decrease. Sometimes. When the content of the wetting agent is large, the viscosity becomes too high at the time of producing the hydrogel, the handleability is lowered, and bubbles may be mixed in at the time of forming the hydrogel. In addition, the resin matrix and water content are relatively small, and the shape retention and ion conductivity may be reduced.

  The wetting agent is not particularly limited as long as it improves the retention of the solvent. For example, polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, glycerin, pentaerythritol, sorbitol; these polyhydric alcohols Polyols polymerized using one or more of these as monomers; saccharides such as glucose, fructose, sucrose, and lactose. The wetting agent may be used alone or in combination of two or more. Moreover, you may have functional groups, such as an ester bond, an aldehyde group, and a carboxyl group, in the molecule | numerator of polyhydric alcohol, or the terminal of a molecule | numerator. Of these, polyhydric alcohols are preferred because they impart elasticity to the hydrogel in addition to the action of retaining moisture. Of the polyhydric alcohols, glycerin is particularly suitable in terms of long-term water retention. Polyhydric alcohols can be used by selecting one or more from these. Among the polyhydric alcohols, those which are liquid at normal temperature are more preferable because they are excellent in improving the elasticity of the hydrogel and handling in production. When it is necessary to increase the elasticity of the hydrogel, known fillers such as titanium oxide, calcium carbonate, and talc may be added.

The electrolyte salt contained in the hydrogel used for the electrolyte layer 12 can be arbitrarily selected from electrolyte salts conventionally used for charge transport. Such a salt is not particularly limited as long as ion conductivity can be imparted to the hydrogel. For example, a halogenated alkali metal salt such as sodium halide such as NaCl, potassium halide such as KCl, or halogenated salt. Halogenated alkaline earth metal salts such as magnesium and calcium halide, and other metal halides such as LiCl; sulfates, nitrates, phosphates and chlorates of various metals such as K ₂ SO ₄ and Na ₂ SO ₄ , Fluorine-containing electrolyte salts such as perchlorate, hypochlorite, chlorite, ammonium salt, LiPF ₆ , LiBF ₄ , LiTFSI, and various inorganic salts such as complex salts; one of acetic acid, benzoic acid, lactic acid, etc. Monovalent or divalent or higher polyvalent carboxylic acids such as phthalic acid, succinic acid, adipic acid, tartaric acid and citric acid Salts: Metal salts of organic acids such as sulfonic acids and amino acids; Organic ammonium salts; Salts of polymer electrolytes such as poly (meth) acrylic acid, polyvinyl sulfonic acid, poly t-butylacrylamide sulfonic acid, polyallylamine, polyethyleneimine, etc. Is mentioned. In addition, even when the hydrogel is insoluble or dispersed, it can be used that dissolves in the hydrogel over time, such as silicate, aluminate, metal oxide. And metal hydroxides.

The content of the electrolyte salt in the hydrogel is preferably 0.01 to 20% by mass, and more preferably 0.1 to 10% by weight. If it is higher than this range, it is difficult to completely dissolve the electrolyte salt in water, and it may be precipitated as crystals in the hydrogel, or the dissolution of other components may be inhibited. If it is lower than this range, the ion conductivity may be inferior.
If the hydrogel used for the electrolyte layer 12 contains an electrolyte, it becomes ion conductive and can move charges, but if it also contains a redox agent, the movement of charges becomes smoother. Examples of such a redox agent include organic materials such as a quinone-hydroquinone mixture and inorganic materials such as S / S ²⁻ and I ₂ / I ⁻ . Further, LiI, NaI, KI, CsI, metal iodides or as CaI _2, tetraalkylammonium iodide, pyridinium iodide, iodine compounds such as quaternary ammonium compounds, such as imidazoline iodide also suitably used .
Moreover, in order to adjust pH of hydrogel, alkalis, such as NaOH and KOH, may be included.

As a method for producing a hydrogel used for the electrolyte layer 12, for example, a polymerized monomer, a crosslinkable monomer, a wetting agent, a polymerization initiator and an electrolyte salt added thereto are dissolved or dispersed in water for crosslinking. Polymerization method, polymerizable monomer, crosslinkable monomer, wetting agent and polymerization initiator dissolved or dispersed in water to crosslink and polymerize resin matrix obtained by impregnation with electrolyte salt, polymerization A linear polymer and a cross-linking agent by adding a cross-linking agent to a dispersion obtained by dissolving or dispersing an electrolyte in a linear polymer obtained by dispersing only a functional monomer in water and polymerizing in the presence of a wetting agent And a method of producing a resin matrix by cross-linking reaction with each other.
If necessary, the hydrogel used for the electrolyte layer 12 may appropriately contain a preservative, a fungicide, a rust inhibitor, an antioxidant, a stabilizer, a surfactant, a colorant, and the like.

A known method can be adopted as a method of laminating the electrolyte layer 12. For example, the method of apply | coating on the conductive layer 11 by coating methods, such as a gravure coat, a bar coat, a screen coat, can be mentioned.
In the case where a hydrogel previously formed into a sheet is used as the electrolyte layer 12, the hydrogel sheet has adhesiveness, so that the hydrogel sheet can be adhered to the conductive layer 11 as it is. This method is preferable when the auxiliary anode 10 is mass-produced by roll-to-roll using the roll wound body conductive layer 11 and the roll wound hydrogel sheet.
When the conductive layer 11 is a single wafer, the conductive layer 11 is prepared by dissolving or dispersing in water a polymerized monomer, a crosslinkable monomer, a wetting agent, a polymerization initiator, and an electrolyte salt. It may be applied to form a sol-like electrolyte layer and then gelled by radical polymerization.
When the auxiliary anode 10 is mass-produced by roll-to-roll, when the electrolyte layer 12 is integrated and wound on a roll, or when it is cut into sheets and stacked, a release paper is placed on the surface exposed to the outside of the electrolyte layer 12. It is preferable to laminate.

In the auxiliary anode 10 of this embodiment, a protective layer 14 is laminated on the conductive layer 11. The protective layer 14 is located on the surface of the auxiliary anode 10 and blocks water and air, thereby preventing the conductive layer 11 and the electrolyte layer 12 from being stained, deteriorated, or damaged. Therefore, the protective layer 14 is preferably formed so as to cover the entire surface of the conductive layer 11 and the electrolyte layer 12.
When the conductive layer 11 is a metal foil or a carbon-containing sheet, the protective layer 14 is preferably a dry laminated resin film or an extrusion laminated resin. In the case where the conductive layer 11 has irregularities such as a metal mesh or punching metal, it is preferable that the resin is previously formed into a flat member such as a sheet or a plate and the periphery thereof is bonded with an epoxy adhesive or the like.

Examples of the resin for forming the protective layer 14 include fluorine resins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and ethylene-tetrafluoroethylene copolymer (ETFE), epoxy resins and methyl methacrylate (MMA). Acrylic resins such as) are preferred because they are excellent in contamination prevention and weather resistance. In addition, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), tetraacetyl cellulose (TAC), polyether sulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAr), poly Resins such as sulfone (PSF), polyetherimide (PEI), polyacetal, transparent polyimide, and polyethersulfone can also be exemplified.
Of these resins, a fluororesin is preferable because it is excellent in weather resistance. In addition, since the fluororesin has a low gas barrier property, a gas such as oxygen or chlorine generated when a current of 10 to 30 mA is applied to prevent corrosion without processing such as providing a large number of holes. The protective layer 14 can be discharged.
When these resins are formed into a film, the protective layer 14 can be laminated by dry lamination, which is preferable when the auxiliary anode 10 is mass-produced by roll-to-roll. Such a film is preferably stretched to increase the strength.

As long as the physical strength is satisfied, the thickness of the protective layer 14 is preferably thin from the viewpoint of the ability to discharge gases such as oxygen and chlorine generated during corrosion prevention and the cost. Specifically, the thickness of the protective layer 14 is 10 to 200 μm, preferably 20 to 100 μm. The protective layer 14 may be formed by laminating a plurality of same or different types of resins.
The protective layer 14 may be colored or may have a design such as character information or a pattern. In particular, it is preferable that the color is a gray color similar to the color of the surface of the concrete layer 3 because the auxiliary anode 10 is not conspicuous.
A method for forming the protective layer 14 is usually formed into a film and laminated on the conductive layer 11 using an adhesive. When the conductive layer 11 is a film conductive layer, the surface of the film substrate on which the electrolyte layer 12 is not attached may be used as the protective layer 14.

As the to-be-corroded body 4 to which the auxiliary anode 10 of the present invention is suitably applied, in addition to those containing iron such as steel (stainless steel, etc.), those containing nickel, titanium, copper, zinc, etc. can be protected against corrosion. . Further, the auxiliary anode 10 is adhered to a surface layer made of an ion-permeable oxide film such as rust present directly or on the surface of a metal covered with a concrete layer or a paint film or a bare metal. These can also be anticorrosive.
When the to-be-protected body 4 is embedded in the concrete layer 3, there is a gel-like substance containing moisture in the extremely small voids in the concrete layer 3. As ions contained in the gel substance, OH ⁻ , Na ⁺ , Ca ²⁺ , K ^{+ and the} like are mainly used. In addition, sodium chloride is infiltrated into the concrete layer of the structure near the sea where corrosion protection is highly necessary. That is, the concrete layer 3 is a solid electrolyte layer having a remarkably large impedance, and can function as an ion conductive layer by these ions. And since the water | moisture content in the concrete layer 3 discharge | releases a water | moisture content in the air by drying or absorbs the water | moisture content in the air by the daily difference of rain water or temperature, the concrete layer 3 will be in an absolutely dry state There is no.

Moreover, the to-be-corroded body 4 to which the auxiliary anode 10 of the present invention is applicable can also be applied to the to-be-corroded body having a coating film formed on the surface. Although the coating film of the paint looks like an insulating layer, the surface of the coating film that requires anticorrosion has many cracks and fine pores into which moisture that causes corrosion enters. These cracks and holes penetrate to the body to be protected. Since the cracks and holes cannot block moisture and air, moisture is present. Accordingly, ions can move in this portion and become ion conductive, and therefore, the auxiliary anode 10 of the present invention can be attached to a paint film to prevent corrosion. And since this anticorrosion should just be performed with respect to the part of this crack and a fine hole, an extremely narrow area will be anticorrosive. Therefore, even if the amount of electrons supplied from the auxiliary anode 10 is small, extremely effective anticorrosion is possible.
In addition, when a hydrogel is used as the electrolyte layer 12, a part of the hydrogel penetrates into cracks and fine holes on the surface and comes into contact with the object to be protected or is located very close. It can reliably prevent corrosion.
Further, since the hydrogel has a resin matrix, the conductive layer 11 is in contact with the metal even when the auxiliary anode 10 is directly bonded to the surface of the metal to be the corrosion-protected body 4 when the metal having the paint film is to be corroded. Does not cause a short circuit.

The anticorrosion structure 1 of the concrete structure of the present embodiment is configured such that the auxiliary anode 10 is attached to the surface layer 3 of the concrete structure using the electrolyte layer 12, and the conductive layer 11 of the auxiliary anode 10 is used as the positive electrode of the power supply circuit 5. Then, the negative electrode of the power supply circuit 5 is connected to the corrosion-protected body 4 using the circuit wiring 6.
The circuit wiring 6 preferably has corrosion resistance against anodic dissolution, and examples thereof include nickel alloys such as carbon, titanium, stainless steel, platinum, tantalum, zirconium, niobium, nickel, monel and inconel. Of these, titanium is preferred because it is readily available and is resistant to anodic dissolution over a wide range of potentials.
Also, an aluminum wire or copper wire that is not resistant to anodic dissolution can be used by being coated with a resin layer.

First, a specimen was prepared in order to conduct an experiment for confirming the anticorrosion effect by intermittent energization.
The concrete of the specimen was ordinary concrete 24-8-20N. In order to corrode the reinforcing bars as early as possible, the water-cement ratio was set to 65%, and 10 kg / m ^{3 of} salt was added.
The dimensions of the specimen were 80 mm thick, 340 mm wide, and 400 mm long, and one rebar with a diameter of 19 mm and a length of 300 mm was embedded. Curing after concrete placement was 1 day in water and 28 days in air.
As the test specimens, two blank non-corrosive anti-corrosion specimens and one anti-corrosion specimen having an electron supply sheet attached to the surface subjected to the kelen treatment were prepared.
Disassemble one of the non-corrosion-proof specimens after curing, and apply a colorant to the corroded part of the rebar with reference to the “Method for evaluating corrosion of steel in concrete” in JCI-SC1 of the Japan Concrete Institute. It was applied and transferred to paper. The surface area of the corroded portion was 8.2% of the total surface area.

As a power supply for intermittent energization, a 300 mm square electron supply sheet prepared according to the specimen of the electron supply sheet described in Example 2 of the anticorrosion structure of Patent Document 4 was used. That is, a sheet of the first conductive hydrogel, a conductive layer having a basis weight and dried by applying about 60 g / m ² of carbon paste at a coverage dry weight PET nonwoven 25 g / m ² holes A semiconductor layer coated with 15 g / m ^{2 of} anatase-type titanium oxide paste by dry weight, a second hydrogel sheet, and a 25 μm ethylene tetrafluoroethylene copolymer (ETFE) film, An electron supply sheet having this order was used.

Another uncorrosion-proof specimen and anti-corrosion specimen were exposed outdoors. In the anticorrosion specimen, a manganese dioxide electrode was embedded as a reference electrode on the back surface (the surface not subjected to keren treatment) of the concrete layer, fixed with mortar, and connected to an electrometer using a lead wire. The anticorrosion specimen was exposed horizontally with the electron supply sheet facing up.
An electrometer was connected to the reinforcing bar potential measuring lead attached to the reinforcing bar of the corrosion protection specimen, and the reinforcing bar potential was measured with the embedded reference electrode, and the generated current density was observed with a non-resistance ammeter. The observed generated current density is shown in FIG. 3, and the rebar potential converted to SCE (saturated calomel electrode) is shown in FIG.

It can be considered that the more the generated current density in FIG. 3 is in the positive direction and the more the rebar potential in FIG. The generated current density in FIG. 3 is in a state in which power is generated in response to light sensitively at sunrise and no power is generated at night. The rebar potential gradually changed in the direction of the natural potential at night, changed in the negative direction during the day, and repeated corrosion prevention. The anticorrosion specimen generates a current of approximately 1 to 3 mA / m ² during the day, and the amount of change in rebar potential during the day and night is about 150 mV. It was higher.
The anticorrosion specimen was cracked after six months of outdoor exposure, so it was judged that the corrosion of the reinforcing bars had progressed, and was disassembled together with the anticorrosion specimen, and the colorant was applied to the corroded portions of the reinforcing bars and transferred to paper. . In the corrosion-free specimen, the surface area of the corroded portion was 51.3% of the total surface area, whereas the corrosion-proof specimen was 6.2%.
From these results, it was confirmed that even with intermittent energization, it has an anticorrosive effect.

Hereinafter, the present invention will be specifically described with reference to examples.
A simple power supply circuit 5 shown in FIG. 2 used in Example 1 of the anticorrosion structure 1 shown in FIG. 1 was produced by the following procedure.
As a main power source, a single crystal silicon solar cell 51 having a silicon surface size of 64 mm square and nominal outputs of Vpm: 4 V and Ipm: 70 mA was prepared.
A diode 52 was connected to the positive electrode of the solar cell 51 in order to prevent a corrosion current from flowing through the body 4 to be protected at night. In order to monitor the current between the object to be protected 4 and the auxiliary anode 10, a resistor 54 is connected in series between the solar cell 51 and the object 4 to be protected, and a voltmeter 57 The amount of generated current can be confirmed by measuring the voltage.
Further, an electrolytic capacitor 53 having a capacity of 1200 μF was connected in parallel with the solar cell 51 between the diode 52 and the auxiliary anode 10. The capacitor 53 is charged by the solar cell 51 in the daytime and supplies electrons to the corrosion-protected body 4 by the charge charged at nighttime. And the voltmeter 58 was connected in parallel between the capacitor | condenser 53 and the to-be-protected body 4 so that the voltage applied to the reinforcing bar 4 could be measured.

Two auxiliary anodes 10 used in Example 1 of the anticorrosion structure 1 were produced by the following procedure.
Powdered graphite is dispersed in an organic solvent on a 38 μm thick PET film 111, and a conductive carbon paste 112 containing a binder is applied and dried to form two conductive layers 11 having a width of 350 mm and a length of 500 mm. did. The amount of carbon powder deposited was about 20 g / m ² by dry weight. The thickness of the conductive layer 11 was 15 μm.
The obtained conductive layer 11 was punched from the PET film surface with a hot needle, and a large number of through holes 15 were formed in the conductive layer 11. A protective layer 14 was obtained by dry laminating an ETFE film having a thickness of 25 μm, which was colored gray by blending a pigment on the PET film surface of the conductive layer 11. At the time of dry laminating, the adhesives 13, 13,... Were spot-gravure coated so that the gas could be removed from between the conductive layer 11 and the protective layer. In addition, when the voltage applied to the reinforcing bar 4 is small and the amount of gas generated by electrolyzing moisture in the concrete or the electrolyte layer 12 is small, the through hole 15 may not be provided. Moreover, you may apply | coat the adhesive agent 13 to the whole surface.

As the electrolyte layer 12, two hydrogel sheets (“Technogel SR-R” manufactured by Sekisui Plastics Co., Ltd.) having a thickness of about 0.8 mm, a width of 300 mm, and a length of about 500 mm were used. The auxiliary powder 10 shown in FIG. 1 was produced by attaching the carbon powder surface of each conductive layer 11 to each electrolyte layer 12 so that the margins around the long sides of the conductive layer 11 were uniform.
A copper tape having a width of 10 mm was attached to one side of the conductive layer 11 exposed at a length of 25 mm on both sides of each of the obtained auxiliary anodes 10 with a conductive adhesive along one side in the longitudinal direction. This copper tape is an installation place of a current discharge point (a positive electrode connection portion of the power supply circuit 5). Further, the power supply material reduces the voltage difference applied when energizing a portion far from the drain point of the conductive layer 11 and a portion near the drain point.

Using the electrolyte layer 12 of the auxiliary anode 10, the corrosion-protected body 4 made of a grid-like reinforcing bar having a diameter of 19 mm is embedded in the center of the layer on the surface of the concrete layer 3 having a thickness of 300 mm, a width of 800 mm, and a height of 700 mm. Two auxiliary anodes 10 were arranged in parallel and bonded to each other with a gap of 100 mm.
For the concrete layer 3, ordinary Portland cement was used as the cement. The specification of the mortar was cement 1, standard sand 3, and water 0.5 according to the mortar composition described in JIS R 5201 “Physical test method for cement”. The water cement ratio in this formulation is 0.50.

The positive electrode of the power supply circuit 5 is connected to the copper tape of the respective conductive layers 11 so that the auxiliary anodes 10 are connected in parallel by the conductive wires 6 made of a copper wire coated with resin, and the negative electrode of the power supply circuit 5 is similarly connected. The lead wire 6 was connected to the reinforcing bar 4.
A pasting type AgCl reference electrode was pasted on the back surface of the concrete layer 3.
The periphery of the protective layer 14 of each auxiliary anode 10 and each connection portion of the copper tape 6 and the copper wire 6 of the conductive layer 11 are sealed with a fluorine resin film and an epoxy adhesive, and the concrete structure shown in FIG. It was set as Example 1 of the anticorrosion structure 1 of a thing.
The solar cell 51 was fixed vertically so as to face the sun at noon, and tilted about 20 degrees horizontally. The voltmeter and the reference electrode were connected to an electrometer, and the circuit voltage (generated voltage) and the potential of the reinforcing bar 4 were measured. Further, the voltage at both ends of the resistor 54 was measured, and the amount of current flowing through the reinforcing bar 4 (the amount of generated current) was measured. These values were recorded at a frequency of once per hour using a small data logger. The results are shown in FIGS. 5 to 10 starting from midnight. The measurement is started from the beginning of December, FIGS. 5 to 7 show the measurement results of 0 to 300 days or more, and FIGS. 8 to 10 show the measurement results of 290 to 300 days.

  According to FIG. 5, the peak of the voltage (voltage applied to the reinforcing bar 4) generated by the solar cell 51 is stable at 3 V to 3.5 V for 300 days or more. However, if you look closely, the generated peak voltage is high until about 140 days from the start, and then low until about 260 days. This is presumably because the measurement started in early December, so the temperature during the day was initially low, and then the temperature during the day rose. It should be noted that no data was collected from the 100th day to the 130th day because the data logger was removed for use in other experiments.

According to FIG. 6, although the current flows for 300 days or more, the daily variation is larger than the voltage of FIG. This is presumably because the operating current of the solar cell is more susceptible to the weather than the operating voltage. Further, since the generated peak current amount is large from the 140th day to the 240th day, it can be seen that the generated current amount increases from spring to summer.
After that, the amount of generated current gradually decreases. The cause of this is presumed that as a result of the progress of anticorrosion, an anticorrosion film is formed on the reinforcing bar 4, the ion distribution in the concrete is changed, or the moisture content of the concrete is lowered, thereby increasing the impedance.
FIG. 6 shows the actual value of the generated current amount. Since ^two auxiliary anodes having an electrolyte layer 12 with an area of 0.15 m ² were used, assuming that the corrosion prevention area is the hydrogel area, the width is 300 mm. Since × 500 mm × 2 sheets = 0.3 m ² , when the peak of the generated current is 0.3 mA, the peak of the generated current density is 1 mA / m ² .

  According to FIG. 7, although the rebar potential has changed by 100 mV or more over 300 days or more, the amount of change gradually decreases, and there is a possibility that the day when it becomes less than 100 mV will come in the future. However, according to FIG. 8, the voltage applied to the reinforcing bar 4 is 3 V to 3.5 V and the peak voltage is stable, so that the moisture content of the concrete increases or the corroding ions are in the reinforcing bar 4. When an environment that tends to corrode is generated due to approaching the surroundings, it is considered that corrosion can be prevented because current flows easily.

  According to FIG. 8, the minimum value of the voltage is about 0.4V and not 0V. This reason is presumed to be due to the charge remaining at the interface of the conductive layer 11 / electrolyte layer 12 and the influence of the reverse current prevention effect of the diode 52. However, according to FIG. 9, since the current value is 0 mA at night, no anticorrosive current flows. Therefore, it is estimated that the active anticorrosive effect at night can not be expected, but it works to suppress the generation of reverse current (corrosion current).

With reference to FIG. 8, the voltage when the current required for corrosion prevention is obtained is approximately 3V, and the current necessary for corrosion prevention at night is 0.2 mA with reference to FIG. 9, the capacity C = 1200 μF (1.2 mF). since a power amount W · s = ^CV 2/2 to be accumulated in the electrolytic capacitor 53, the electric energy W · s = 1.2 × 3 × 3/2 = 5.4mJ (5.4mW · s).
And since the electric power consumed in Example 1 of the anticorrosion structure 1 is 3 V × 0.2 mA = 0.6 mW, if power is consumed at a constant voltage, 5.4 mW · s / 0.6 mW = 9 seconds. It becomes. Even if power is consumed while the voltage drops linearly, it takes 18 seconds.
That is, the electrolytic capacitor 53 having a capacity of 1200 μF in the embodiment of the anticorrosion structure 1 has a small capacity, and does not have a power storage function that allows a current that can be anticorrosive to flow through the reinforcing bars 4 at night. However, as a result of the anticorrosion effect being confirmed even at night when no voltage is applied to the reinforcing bar 4 due to the intermittent energization described above, the anticorrosion of the concrete structure in which the reinforcing bar with a light degree of corrosion is embedded or the newly constructed concrete structure is It seems possible.

Next, the power supply circuit 5 used for Example 2 of the anticorrosion structure 1 shown in FIG.
As a main power source, a polycrystalline silicon solar cell 51 having a silicon surface size of 12 mm × 156 mm connected in series and having nominal outputs of Vpm: 18 V and Ipm: 277 mA was prepared. Between the diode 52 and the auxiliary anode 10, an electric double layer capacitor 53 having a capacity of 120 F was connected in parallel with the solar cell 51. Further, a current control circuit capable of adjusting the amount of current with a variable resistor 61 by combining the Zener diode 59 and the transistor 60 is provided.
Except for these, the power supply circuit 5 was the same as that used in Example 1 of the anticorrosion structure 1.

A single auxiliary anode 10 used in Example 2 of the anticorrosion structure 1 was produced in the same manner as the auxiliary anode 10 used in Example 1 of the anticorrosion structure 1 except that the hydrogel sheet had a width of 300 mm and a length of about 350 mm. .
In the same manner as in Example 1 of the anticorrosion structure 1, a concrete layer 3 having a thickness of 50 mm, a width of 400 mm, and a length of 600 mm in which an anticorrosive body 4 made of a grid-like reinforcing bar having a diameter of 10 mm was embedded in the center of the layer was produced. Using the electrolyte layer 12, the auxiliary anode 10 was bonded to the center of the surface of the concrete layer 3 with the width direction aligned.
In the same manner as in Example 1 of the anticorrosion structure 1, the solar cell 51 was connected to the power supply circuit 5 used in Example 2 of the anticorrosion structure 1 to obtain Example 2 of the anticorrosion structure 1 of the concrete structure shown in FIG.

  The generated voltage and generated current amount were the same as in Example 1 of the anticorrosion structure 1 except that the solar cell 51 was installed horizontally, the recording was performed once every 10 minutes, and the measurement was started from the beginning of July. And the rebar potential was recorded. In addition, it spent on the adjustment of the power supply circuit 5 until the 6th day. The capacitor 53 was connected on the night of the 6th day, and the current amount was controlled to be always energized until noon on the 17th day without controlling the amount of current. Thereafter, the capacitor 53 was removed for intermittent energization, and the current amount was controlled to 0.5 mA until 10:00 am on the 21st day. Thereafter, the current amount was controlled to 0.6 mA until 10:00 on the 24th day. Thereafter, the current amount was controlled to 1 mA until the 59th day. The results are shown in FIGS. 12 to 14 starting from 3 am. Moreover, the result of 45th-55th day is expanded and it shows in FIGS. 15-17.

According to FIG. 12, while using the capacitor 53, although there is a small fluctuation, a voltage of about 0.8 V is applied at night, and from FIG. 13, a current of about 0.2 mA flows at night. You can see that FIG. 13 shows an actual measurement value of the current. The anticorrosion area is such that the hydrogel area is 300 mm wide × 350 mm long = 0.105 m ^2, and thus the generated current of 0.2 mA is the generated current density. This corresponds to about ² mA / m ² . And according to FIG. 14, since the rebar electric potential changes about 170 mV at night, it turns out that it is fully corrosion-protected by always energizing.

From FIG. 13, it can be seen that if a current control circuit is provided, even a power supply circuit using a solar cell as a main power source can be prevented from corrosion by intermittent energization with a constant current. In the case of the combination of this current control circuit and this specimen, the circuit voltage can be suppressed to about 1.3 V or less. Therefore, the corrosion prevention of intermittent energization according to Example 2 of the anticorrosion structure 1 is the electrolysis of water and chloride. Hard to happen. In addition, the current amount 1 mA at the time of corrosion prevention by intermittent energization in FIG. 13 corresponds to the generated current density of about 10 mA / m ² . As a result, the peak of the amount of change in the reinforcing bar potential is as large as about 350 mV, but it is considered that over-corrosion is unlikely to occur if intermittent energization is performed.
In addition, when the capacitor 53 is not used and intermittent energization is performed, there is no day with no generated current, and thus it can be seen that the anticorrosion current flows even when the amount of generated current is cloudy or rainy during the day.

And when the capacitor | condenser 53 is used, since the electric potential of a reinforcing bar has fallen 100 mV or more also at night, it turns out that it is corrosion-proof at night. Then, referring to FIGS. 13 and 12, assuming that the current required for nighttime anticorrosion is 0.2 mA and the voltage at that time is 0.8 V, the power consumed by Example 2 of the anticorrosion structure 1 is 0.8 V × 0.2 mA = 0.16 mW. The capacitance C = because 120F is a power amount W · s = ^CV 2/2 stored in the capacitor 53 of the power amount W · s = 120 × 0.8 × 0.8 / 2 = 38.4 Joules (W S)
Assuming that the capacitor 53 supplies power at a constant voltage at night, 38.4 W · s / 0.16 mW = 240000 seconds = about 67 hours. Therefore, it can be seen from FIG. 16 that the time zone without the generated current is about 10 hours, but even if it is longer, the anticorrosion current can be supplied with a margin at night.

  In addition, according to the intermittent energization in Example 1 of the anticorrosion structure 1 and the constant energization and the intermittent energization in Example 2, it can be seen that the anti-corrosion is possible by operating the solar cell without performing the maximum power point tracking. .

DESCRIPTION OF SYMBOLS 1 ... Corrosion prevention structure of this invention, 3 ... Surface layer (concrete layer), 4 ... Corrosion object (rebar), 5 ... Power supply circuit, 51 ... Solar cell, 52 ... Diode, 53 ... Capacitor (capacitor), 54 ... Resistance , 55... Positive electrode of power supply circuit, 56... Negative electrode of power supply circuit, 6... Circuit wiring (conductor), 10 .. auxiliary anode, 11 ... conductive layer, 12 ... electrolyte layer, 14 ... protective layer, 15. ).

Claims (9)

An auxiliary anode in which an electrolyte is formed in a sheet shape on one surface of the conductive layer formed in a sheet shape and a gel electrolyte layer having an adhesive force that can be attached to the surface layer of the conductive layer and the corrosion-protected body is attached. The gel electrolyte layer is attached to the surface layer of the object to be protected, the conductive layer of the auxiliary anode is connected to the positive electrode of the power circuit including the solar cell, and the negative electrode of the power circuit is used as the object to be protected. Anti-corrosion structure characterized by being connected.   The anticorrosion structure according to claim 1, wherein the conductive layer includes a carbon material.   The anticorrosion structure according to claim 2, wherein the carbon material is supported on a fiber substrate or a film substrate.   The anticorrosion structure according to claim 3, wherein the carbon material is carbon powder.   The anticorrosion structure according to any one of claims 1 to 4, wherein the conductive layer has a large number of communication holes through which gas can permeate.   The anticorrosion structure according to any one of claims 1 to 5, wherein an outer surface of the conductive layer is covered with a protective layer. The said auxiliary anode of the anticorrosion structure in any one of Claim 1 thru | or 6 is stuck to a concrete structure using the said gel electrolyte layer, The said electroconductive layer of the said auxiliary anode is a power supply circuit containing a solar cell. An anticorrosion method comprising: connecting to a positive electrode; and supplying an electric current by connecting the negative electrode of the power supply circuit to an anticorrosive body embedded in a concrete structure.   The anticorrosion method according to claim 7, wherein a current is supplied to the object to be protected without using a secondary battery as a power storage unit.   The anticorrosion method according to claim 8, wherein the solar cell is operated without performing maximum power point tracking.

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