JP2007205012A - Repair method of anticorrosion coating for steel structure and underwater repair sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underwater repair method for corrosion-proof coating of a steel structure manufactured from material mainly formed of steel. <P>SOLUTION: This repair method for corrosion-proof coating of the steel structure is characterized in that a resin sheet or a resin sheet with an inorganic layer of metallic foil, metal vapor deposition, or the like is bonded to a defect part through an adhesive sheet when a defect such as a hit mark of a corrosion-proof coating occurs in the corrosion-proof coating of the steel structure installed underwater. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for repairing an anticorrosion coating of a structure manufactured with a material mainly composed of steel and partially or entirely immersed in water, and an underwater repair sheet.

  Steel structures installed underwater, especially in seawater, are formed with anti-corrosion coatings that are several millimeters thick, especially in areas where steel materials are susceptible to corrosion, in order to prevent corrosion of steel materials. Yes. This film is applied in a factory by sticking a resin sheet to a steel material or spraying a resin. Steel sheet piles or steel pipe sheet piles are most widely used as steel materials that are immersed and constructed in the sea.

  A method of coating the surface of a steel structure with a resin sheet and a method of performing this in water have been developed. For example, JP-A-57-11194 (Patent Document 1), JP-A-2-190529 (Patent Document 2), JP-A-1-172833 (Patent Document 3), and JP-A-60-8058 ( Patent Document 4) and the like. In particular, in repairing steel structures that are actually used, it goes without saying that application of a resin sheet is excellent in workability.

  When steel materials with anti-corrosion coating at the factory are transported to the construction site, and when civil engineering work is performed such as driving into shallow water, it is completely prevented that the anti-corrosion coating is wrinkled due to some factor, such as dents. It is extremely difficult to do. Moreover, when a sag enters during construction, it is difficult to find the sledge, and in some cases, after the steel structure is completed, the sledge is discovered in the water. Or, for example, a defect of the anticorrosion coating may occur due to an accident such as a collision of a floating material such as driftwood with a large mass. These defects accelerate the peeling of the anticorrosion film, and in some cases, the entire anticorrosion film may fall off in an unexpected short time.

  As a method of repairing the peeling of the anticorrosive film, using a hammering, tapping screw, bolt and nut, etc., the anticorrosion coating and the steel material are physically adhered to each other to suppress the progress of the peeling, or a chamber is installed in the buttock. For example, JP-A-60-246930 (Patent Document 5) and JP-A-63-166467 (Patent Document 6) disclose a method for temporarily removing water. In addition, paints that can be coated and cured in water have been developed. A method using the same, a method of preparing an integrally molded anticorrosive body and attaching it, for example, Japanese Patent Application Laid-Open No. 57-55915 (Patent Document 7) and Japanese Patent Application Laid-Open Japanese Patent Laid-Open No. 58-29916 (Patent Document 8) and the like.

  However, performing hammering, screwing, etc. in water requires a special device and is not easily performed. Further, the method of physically fixing these coatings can delay the progress of peeling, but does not prevent the peeling itself. It is known that the underwater paint has low adhesion and is easy to peel off, and it is more difficult to coat a resin sheet having a low surface energy such as polyethylene. Needless to say, the use of the integrally molded anticorrosive body is applicable only when the damaged part is known in advance.

  On the other hand, although various repairs using an adhesive sheet have been developed, all of them are premised on the work in the atmosphere, for example, Japanese Patent Laid-Open No. 61-90774 (Patent Document 9) and a special technique. Japanese Unexamined Patent Publication No. 63-199885 (Patent Document 10) and the like. For this reason, the process of sticking an adhesive sheet after filling a putty, resin, etc. is taken. However, it goes without saying that simple work is desirable for underwater repair work.

Japanese Patent Laid-Open No. 57-11194 JP-A-2-190529 Japanese Unexamined Patent Publication No. 1-172583 Japanese Unexamined Patent Publication No. 60-8058 JP 60-246930 A JP-A 63-166467 JP-A-57-55915 JP 58-29916 A JP-A-61-90774 JP 63-199885 A

  Then, this invention aims at providing the method of suppressing the chemical reaction itself which produces peeling by a simple method as a repair method of the anticorrosion film in water.

In the present invention, attention is paid to the factors that cause the peeling of the anticorrosion coating of steel to proceed. And in order to suppress the reaction which raise | generates peeling, it discovered that the supply of oxygen to the steel surface should just be prevented, and completed this invention.
In order to suppress the reaction, it is important to cover the heel part with a material having low permeability of the corrosive factor, and even if water is confined in the dent part where the crease is formed, it is a practical problem in suppressing the peeling. I found that there was no. Further, it has been found that if the bonding force when a material covering the buttock is attached also has a value of a certain level or more, it has little to do with the suppression of peeling. For this reason, although it was inferior to an adhesive agent in joining force, it turned out that the objective is fully achieved by joining using the adhesive sheet with easy work.

That is, in the first aspect of the present invention, a repair sheet made of an adhesive sheet in which a resin sheet or a resin sheet having an inorganic layer is attached on one side to a defective portion generated in a corrosion prevention coating of a steel structure installed in water is submerged in water. A method for repairing an anticorrosion coating of a steel structure characterized by bonding.
Secondly, a repair sheet made of an adhesive sheet having a corrosion-resistant metal foil attached on one side is bonded to a defective portion generated in the anticorrosion coating of the steel structure installed in water. This is a method of repairing the anticorrosion coating.

  Third, in adhering the repair sheet to the anticorrosion coating of the steel structure in water, after removing the release paper affixed to the adhesive surface of the repair sheet in the air, immediately in a container filled with clean water The first or the second is attached to the defective part of the anticorrosion coating by moving the container together with the container to the work place in the water and immediately before sticking, the adhesive surface is transferred to the repair work part without touching the air. 2 is a method for repairing an anticorrosion coating of a steel structure according to 2.

4th is the repair method of the anticorrosion coating | cover of the steel structure as described in said 1st which the said resin sheet consists of resin with low oxygen permeability.
5th is the repair method of the anticorrosion coating | cover of the steel structure of said 1st whose said inorganic material layer is metal foil or a metal vapor deposition film.
The sixth is an underwater repair sheet made of an adhesive sheet having a protective layer with low oxygen permeability on one side and a release paper for surface protection on the other side.

Seventh is the repair sheet for underwater according to the sixth, wherein the protective layer is a resin sheet or a resin sheet having an inorganic layer.
Eighth is the underwater repair sheet according to the sixth, wherein the protective layer is a corrosion-resistant metal foil.
The ninth is the underwater repair sheet according to the seventh, wherein the inorganic layer is a metal foil or a metal vapor deposition film.

By using the method for repairing an underwater corrosion protection film of a steel structure according to the present invention, repair in water can be easily and reliably performed at low cost.
Moreover, repair work can be advanced promptly by preparing the repair sheet | seat by the combination of a various protective layer and an adhesive sheet previously.

The present invention will be described in detail below.
The present invention relates to a resin sheet having an inorganic layer such as a resin sheet, a metal foil, or a vapor-deposited metal layer on a defective portion (a vicinity including a defect or a peeled portion) generated in an anticorrosive coating of a steel structure installed in water. Is a method for repairing an anticorrosion coating of a steel structure, wherein the steel structure is bonded in water through an adhesive sheet.

If the coating material used in the present invention is a resin sheet, a nylon resin, a polyvinyl chloride resin, a polyethylene terephthalate resin, a polyolefin resin such as polyethylene, or a resin sheet mainly composed of these derivatives can be used. . Among these, paying attention to the permeability of oxygen which is a corrosive factor, the polyethylene terephthalate resin (unstretched agent) is 5.0 ml · mm / m ² · day · atm, and is a high density polyethylene often used for anticorrosion coating. Compared with 85 ml · mm / m ² · day · atm of (unstretched material), the oxygen permeability is low, and the price is low as a resin sheet.

  From the standpoint of performance alone, the oxygen permeability of ethylene-vinyl alcohol copolymer resin (trade name EVAL, manufactured by Kuraray Co., Ltd.) is 1/10 or less that of polyethylene terephthalate, and this can also be used. Moreover, you may use the laminated material of these resin. Needless to say, the thickness of the resin sheet is better from the viewpoint of barrier properties. However, if the resin sheet is thick, it becomes hard, so workability deteriorates. Especially, it is bonded to curved surfaces and corners that are easily wrinkled, and the resin sheet is gradually applied while bending so that water does not enter the interface. Can be difficult. For this reason, although depending on the kind (hardness) of the resin sheet, a thickness in the range of 0.2 mm to 1.0 mm is preferable.

When higher performance is required, an inorganic layer such as a metal or metal oxide can be formed on the adhesive sheet-attached surface of the resin sheet by a method such as vapor deposition. In this case, the formation of a layer of titanium, silica or the like is effective in that it does not react with seawater. If the thickness of the inorganic layer in this case is 0.5 μm at the maximum, a sufficient effect can be expected.
Of course, it is also possible to affix a corrosion-resistant metal foil, and in this case, not only the gas such as oxygen but also the permeation of water as other corrosive factors can be completely blocked. Usually, the metal used to coat steel materials used in the marine environment is limited to titanium, which is a metal that does not react with seawater.

  In a fresh water environment, general-purpose stainless steel having good corrosion resistance such as SUS304 can be used. However, when the steel material and the attached metal come into contact with each other, a battery is formed, and the corrosion of the steel material may be accelerated. Therefore, both of them must be completely insulated, but this is difficult with a large-area coating. However, in this method, since the area to be used is small and the adhesive sheet is bonded onto the anticorrosion resin coating, there is no major problem in using the corrosion-resistant metal foil in terms of cost and insulation.

  If the thickness of the metal foil is several μm, the function as a barrier can be sufficiently achieved. However, when the metal foil is used alone, it is about 50 to 100 μm from the viewpoint of physical strength. Thickness is necessary. Of course, it is also possible to use a combination of a metal foil and a resin sheet. In this case, a function as a barrier is sufficient if the thickness is 0.5 μm or more, as in the case of vapor deposition on a resin. However, it is not practical to produce such a thin metal foil. Further, even if the metal foil is reduced in thickness, the cost per unit area is not necessarily reduced. For this reason, it is necessary to consider the cost effectiveness and determine the specifications. Usually, a metal foil having a thickness of 10 to 100 μm is mass-produced and is commercially available, so it is preferable to select a thickness within this range. In order to increase the flexibility of the entire sheet from the viewpoint of workability, it is desirable to use a thin metal foil of about 10 to 40 μm.

  The pressure-sensitive adhesive sheet is first required to be able to perform a pressure-sensitive adhesive operation in water. As long as the inventors have tested, after attaching the end of the adhesive sheet to the material to be joined, if the joining operation is performed while gradually extruding water so that the interface does not contain water, many commercially available adhesives can be obtained. With the sheet, the initial bonding force is equivalent to that in the air. Here, even if there is a portion where water remains in the wrinkled recess and the adhesive sheet is not in close contact, the area of the portion is about 10% or less of the entire pasted area, and the vicinity of the center of the adhesive sheet If so, it does not lead to a decrease in the overall bonding force.

  As the bonding force with the repaired film, if the 180 ° peeling force had a value of 3 N / 10 mm or more, the anticorrosion ability was sufficient. This value is a value that can be easily secured by using a pressure-sensitive adhesive sheet for a low surface energy material even when the repair coating has poor adhesion like polyethylene. However, depending on the type of pressure-sensitive adhesive, it is necessary to determine the working conditions because it has characteristics such as those that require long-time pressure bonding and poor bonding strength at low temperatures.

  Next, what is required of the pressure-sensitive adhesive sheet is long-term durability in water, and it is desirable that the material has a track record of long-term use, such as acrylic or butyl rubber-based materials. Also, the pressure-sensitive adhesive sheet needs flexibility and a certain thickness. This is to make it easy to bend and apply pressure by hand when it is gradually stuck in water that is difficult to work so as not to contain water at the interface. However, when the pressure-sensitive adhesive sheet layer becomes thicker, corrosion factors such as oxygen diffuse and penetrate into the pressure-sensitive adhesive sheet along the surface from the end face of the sheet, so that the anticorrosion property is lowered. According to the tests by the inventors, although depending on the combination of the resin sheet and the metal foil, if the adhesive sheet has a maximum thickness of about 0.8 mm, the affixing operation in water was possible. The maximum thickness of the sheet is 0.8 mm. If the minimum thickness was 0.2 mm or more, pressure bonding was possible even in work with gloves in water.

  As other performances, in order to suppress the diffusion of the above-mentioned corrosion factors as much as possible, when a foam material is used for the base material of the pressure-sensitive adhesive sheet, it is preferable to have closed cells and a small amount of bubbles. Also, some resins, such as urethane, need to be noted because some resins hydrolyze or dissolve when immersed in water for a long time. In addition, depending on the type of the pressure-sensitive adhesive sheet, the cause is unknown, but there is also a product in which the bonding strength is clearly reduced by prolonged warm water immersion. For this reason, since many adhesive sheets are marketed, what satisfy | fills the above conditions should just be used after a test by actual warm salt water immersion.

  As described above, it is not necessary to fill the dents of the anticorrosion coating with an adhesive, putty, or the like before covering the collar with the adhesive sheet. The stripping of the anticorrosion coating is caused by a chemical reaction between the exposed steel surface and the coated steel surface. Therefore, by stopping the supply of the corrosion factor to the buttock and its surroundings, the chemical reaction is stopped and the peeling does not proceed. The present invention stops the chemical reaction by shutting off the supply of oxygen and / or water to the coated steel surface in the vicinity of the buttocks. For this reason, even if it coat | covers in the form which confine | seales seawater in the dent of a collar part, there is no problem as repair.

  Actually, the resin sheet or the metal foil and the pressure-sensitive adhesive sheet are bonded in advance by a dedicated laminating apparatus or the like, and are completely bonded by performing pressurization and heat retention as necessary. Hereinafter, this is referred to as a repair sheet. If necessary, a primer or the like is applied to the resin or the metal foil, and in the case of a resin, the bonding property may be improved by a method such as performing a corona discharge treatment. In the actual repair work at the site (underwater), remove dirt, dust, attached organisms, etc. around the heel, and remove the rust of the anticorrosive film on the heel, and then use sandpaper, etc. Clean and flatten the surroundings.

  Thereafter, the repair sheet is cut into an appropriate size in water, the release paper of the adhesive material is peeled off, and the adhesive sheet is attached to the buttock. When affixing, attach one end of the repair sheet to the adherend, then gently bend the repair sheet and apply it little by little while extruding water. After sticking, use a roller or the like to sufficiently press. In some cases, the repair sheet may be cut immediately before the pasting operation is completed. Thus, it is very easy as repair work in water. As is clear from using a thin adhesive sheet of 0.8 mm or less, it is important that the surface to be attached is clean and flat. For this reason, it is a repair method suitable for repairing the anticorrosion coating of an offshore structure immediately after construction.

  Here, the biggest problem in the joining operation using the pressure-sensitive adhesive sheet is a decrease in pressure-sensitive adhesive force due to adhesion of foreign substances. When peeling paper is peeled from the adhesive sheet in water, if a large amount of fine foreign matters such as clay are floating in the water, this adheres to the adhesive sheet, making bonding difficult. As a result of examining a method for eliminating the influence of this foreign substance floating, if the water that first contacts the adhesive sheet is clean and does not contain foreign substances, the adhesive force is unlikely to decrease even if it comes into contact with water with floating substances after that. I found out.

  For this reason, the work to remove the release paper from the repair sheet is performed in clean water, or after it is performed in air, it is immediately immersed in clean water so that the water in the work environment can be removed without touching the adhesive surface to the air. If brought into a suspended environment, joining work is possible. This is considered to be because a clean water adsorption layer is formed on the surface of the pressure-sensitive adhesive sheet, and direct contact with suspended matter is less likely to occur. Therefore, various restrictions are imposed on the work, such as joining immediately after the adhesive sheet is taken out from clean water, or moving it slowly in water in which foreign matter floats. In addition, the pure water said here is enough about a tap water, and does not require high-purity water called pure water or distilled water.

  In actual work, the repair sheet is cut into an appropriate size in advance, the release paper is removed in the air, then immersed in clean water, and the container is placed in an appropriate manner so that the adhesive surface does not come in contact with anything other than water. Fasten to the wall. The work up to this point is performed as a preparatory work, and it is sufficient to concentrate on the pasting work in water and the work of cutting and removing unnecessary portions of the repair sheet immediately before the end of the pasting work. Thereby, even when there are fine suspended matters in the water, the repair according to the present invention is possible. Of course, this technique does not guarantee complete retention of adhesive strength. The present invention using the pressure-sensitive adhesive sheet cannot be applied when the working environment is extremely bad, such as the amount of suspended matter in the water is so large that foreign matter immediately adheres and settles on the cleaned anticorrosive film.

  Needless to say, the repair sheet to be applied has a wider and thicker anticorrosion ability. However, the wider and thicker the workability decreases, and in reality, there is a possibility that the risk of peeling increases. For this reason, in actual work, it must be selected on the spot depending on the cleanness of the attached surface, the presence or absence of irregularities, whether it is flat or curved. As a guide, as shown in the examples described later, if the anticorrosion film is covered 30 mm or more wider than the heel part, sufficient anticorrosive ability can be exhibited. In some cases, the repair sheet may be doubled. Since the repair sheet becomes softer when the resin sheet having a half thickness is doubled than the thick resin sheet, the operation is obviously easier. In particular, when affixing to a curved surface, the stress is reduced, which is advantageous from the viewpoint of bondability.

Hereinafter, the present invention will be described in detail with reference to examples.
Example 1
Both sides are coated with a synthetic rubber adhesive for low surface energy materials using a foamed acrylic resin as the base material on each of the 0.2mm and 0.5mm thick amorphous PET resin sheets that have been improved by corona discharge treatment on one side. A double-sided adhesive sheet having a thickness of 0.64 mm was attached to prepare a repair sheet. Similarly, the same pressure-sensitive adhesive sheet was attached to the titanium vapor-deposited surface of the same PET resin sheet obtained by vapor-depositing titanium having a thickness of 0.2 μm on one side and a titanium foil having a thickness of 0.1 mm to obtain a repair sheet.
As a comparative example, in the anticorrosion test, repair was performed by a method of fixing a polyethylene sheet around the buttock to four tapping screw steel materials and a method of filling the buttock with an underwater curing type epoxy resin.

[Anti-corrosion test]
A 150 mm × 150 mm × 4.5 mm hot-rolled steel sheet was shot blasted, and after applying an epoxy primer, a 1.0 mm thick polyethylene sheet was attached using a hot-melt modified polyethylene adhesive. A 10 mm diameter iron reaching the iron surface was put into the coating using an end mill, the back and side surfaces were sealed with a tar epoxy paint, and then immersed in a 3% NaCl solution at 50 ° C. for 10 days to obtain a test piece. After cooling in the solution, the above-mentioned repair sheet cut into 60 mm × 60 mm was stuck in the solution, and further immersed at 50 ° C. for 100 days.
A screw fixing operation and a filling operation of the collar portion, which are comparative examples, were also performed in the solution, and the exposed screw heads were covered with an underwater curing type epoxy resin. In addition, the results when no repair work was performed were also investigated. After the test was completed, the coating was peeled off, and the peel width of the epoxy primer from the first ridge was measured. The evaluation results are shown in Table 1.

[Adhesion test]
In accordance with JIS Z 0237, a pressure-sensitive adhesive sheet for general materials in which an acrylic pressure-sensitive adhesive is adhered to both surfaces of a foamed acrylic sheet, a low-surface energy pressure-sensitive adhesive sheet used in the above-described invention examples, and underwater curing used in a comparative example Using a mold resin, 180 ° peeling force was measured on a 0.1 mm thick nylon film, a shot blasted 4.5 mm thick hot-rolled steel sheet, and a 1.0 mm polyethylene sheet as a material to be repaired. Bonding was performed in a 3% NaCl solution, the temperature was raised to 50 ° C., and the measurement was taken out after 100 days. As a comparison, measurement was also performed on a test piece stuck and retained in the air. The test results are shown in Table 2.

  No. 8 is peeling in the first 10-day immersion of the test piece. Invention Example No. In 1, 2, 3, and 4, the progress of peeling is about 1 to 10 mm, and the suppression effect of peeling is clear. Further, as the covering material becomes thicker, and when titanium is used, the repair performance is clearly improved as compared with the case of using only the PET resin. Comparative Example No. No. 5 is one in which the raised polyethylene coating is physically fixed to the steel plate surface with a tapping screw. In this case, the peeling reaction itself cannot be suppressed even though the film is suppressed from floating. Comparative Example No. 6 is the one in which the collar portion is filled with resin. Even after the test, the resin was adhered to the buttocks, but peeling was progressing. No. in Table 2 As can be seen from FIG. 10, the water-cured epoxy resin has good bonding with the steel material, but has low adhesion to the polyethylene sheet, and it is considered that a gap was formed between the water-cured resin and the polyethylene resin.

(Example 2)
A 0.3 mm thick nylon-6 resin sheet was joined to one surface of a 0.6 mm thick acrylic double-sided pressure-sensitive adhesive sheet to prepare a repair sheet. After removing the release paper, it was immersed in tap water in a beaker. After mixing 50 g of fine particle cement with an average particle size of 4 μm in 10 L of tap water, stirring and suspending, immerse the repair sheet with the beaker in the suspension so that the repair sheet does not come into contact with air. After leaving still for 5 minutes, it was crimped and joined to another 1.0 mm thick nylon-6 resin sheet in the suspension. As a comparative example, the release sheet of the repair sheet was removed in the suspension, and after leaving it in the suspension for 5 minutes and 30 minutes, the test piece was pressure-bonded and joined in the same manner as another PET sheet, and After all joining operations were performed in air, a test piece immersed in the suspension was prepared.
About the above 4 test pieces, 180 degree peeling force was measured according to JIS Z 0237 immediately after joining and after being immersed in suspension for 10 days.

No. No. 11 is a method in which a resin sheet is bonded in a suspension using an adhesive sheet in the method of the present invention. Compared with No. 14, there is almost no decrease in bonding force. Nos. 12 and 13 clearly have a small bonding force, and the longer the time of standing in suspension, the greater the decrease in bonding force. This is because the release paper is removed in the suspension, and foreign substances adhere to the surface of the pressure-sensitive adhesive sheet and are cheap.


Patent applicant: Nippon Steel Corporation
Attorney Attorney Shiina and one other

Claims (9)

A steel structure characterized in that a repair sheet made of an adhesive sheet in which a resin sheet or a resin sheet having an inorganic layer is stuck on one side is bonded in water to a defective portion generated in a corrosion prevention coating of a steel structure installed in water. Repair method of anti-corrosion coating of objects. Repair of anti-corrosion coating for steel structures, characterized in that a repair sheet made of an adhesive sheet with a corrosion-resistant metal foil attached to one side is bonded in water to a defective part of the anti-corrosion coating of a steel structure installed in water Method. In adhering the repair sheet to the anticorrosion coating of the steel structure in water, after removing the release paper attached to the adhesive surface of the repair sheet in the air, immediately immerse it in a container containing clean water, 3. The steel according to claim 1 or 2, wherein the container is moved to an underwater work place, and immediately before being attached, the adhesive surface is transferred to the repair work water without touching the air and adhered to a defective portion of the anticorrosion coating. Repair method for anti-corrosion coating on structures. The method for repairing an anticorrosion coating for a steel structure according to claim 1, wherein the resin sheet is made of a resin having low oxygen permeability. The method of repairing an anticorrosion coating for a steel structure according to claim 1, wherein the inorganic layer is a metal foil or a metal vapor deposition film. An underwater repair sheet comprising a pressure-sensitive adhesive sheet having a protective layer having low oxygen permeability on one side and a release paper for surface protection on the other side. The underwater repair sheet according to claim 6, wherein the protective layer is a resin sheet or a resin sheet having an inorganic layer. The underwater repair sheet according to claim 6, wherein the protective layer is a corrosion-resistant metal foil. The underwater repair sheet according to claim 7, wherein the inorganic layer is a metal foil or a metal vapor deposition film.