JPH0417137B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a method of protecting underwater steel structures in the ocean, rivers, etc., which includes surface corrosion protection using a sheet and prevention of weather resistance deterioration of the sheet. (Prior Art) In structures used in oceans or rivers, such as steel sheet piles or steel piles for remaining bridges, long-term corrosion protection, especially in underwater or splash zone parts, is extremely important, needless to say. For this reason, methods for using various materials or construction methods have been proposed, such as applying underwater anti-corrosion paint to such structures, or composite anti-corrosion methods using underwater adhesives and various sheets. There is. However, when applying an adhesive to a wet surface such as underwater or a splash zone, or when applying adhesive to a sheet etc. using an adhesive, water,
The initial adhesion of the adhesive used is poor due to the influence of seawater, etc., and mechanical obstacles such as waves and water currents may cause the sheet to shift, peel, or be washed away before its function is fully demonstrated. Therefore, sufficient effects could not be expected. By the way, in order to solve the various problems mentioned above, one of the inventors of the present invention previously developed a method in which a waterproof sheet coated with an adhesive was delayed crimped onto the surface of an underwater steel structure, and the sheet was attached using magnetic force. We proposed a protection method that consists of However, even with this method, the splash zone of an underwater steel structure is located near the water level, where parts are coated or uncoated due to the ebb and flow of the tide, or in the upper part of the water, that is, relatively close to the water surface. In some areas, there was a problem that the waterproof sheet deteriorated due to ultraviolet rays due to sunlight. (Problems to be Solved by the Invention) The present invention is applicable to steel structures located underwater in the ocean or rivers, as well as parts near or slightly above the water surface, such as splash zones and parts where the wetted surface rises and falls due to the ebb and flow of the tide. It is an object of the present invention to provide a method of protecting the surface of a steel structure by using a sheet to prevent corrosion and to prevent the sheet from deteriorating due to ultraviolet rays. (Means for Solving the Problems) An object of the present invention is to coat a waterproof sheet, which has at least one kind of coating selected from polyurethane resin, silicone resin, and fluororesin on one side, in the air. The adhesive is applied to the surface of the steel structure in the water or the wet surface of the steel structure above the water level, and the sheet is placed on the surface. This is achieved by attaching the sheet to the surface of the steel structure by magnetic force. The present invention will be explained in more detail below. First, the "waterproof sheet" used in the method of the present invention
Examples include chlorosulfonated polyethylene, polyisobutylene, chlorinated polyethylene, natural rubber, styrene rubber, butadiene rubber, chloroprene rubber, butyl rubber, nitrile rubber, acrylic rubber, ethylene propylene rubber, urethane rubber,
A flexible rubber sheet such as silicone rubber or fluorine rubber, or a plastic sheet is used. Its thickness is not particularly limited. However, it is preferably about 0.05 to 10 mm. Further, the shape thereof is not particularly limited and may be any shape such as continuous or tiled. In the method of the present invention, the "waterproof sheet"
is attached to the surface of steel structures using magnetic force. As described below, the methods include making the waterproof sheet itself magnetic and attaching it to the steel structure by its own magnetic force, or attaching the waterproof sheet and then pressing it with a permanent magnet. take measures. In the former case, that is, to impart magnetism to the waterproof sheet, magnetic particles such as ferrite represented by the general formula MO.(Fe ₂ O ₃ ) _o are mixed into the waterproof sheet. In the general formula, M represents a divalent metal or lead, and n is a constant integer value. Specific examples include BaO・6Fe ₂ O ₃ , Sro・6Fe ₂ O ₃ , PbO・
Examples include 6Fe ₂ O ₃ and CaO.2Fe ₂ O ₃ . The magnetic fine particles have an average particle diameter of about 0.1
It has a diameter of about 20 μm, and is contained in the waterproof sheet in an amount of about 30 to 95% by weight. In the present invention, using the above-mentioned materials,
A flexible magnetic waterproof sheet can be obtained by magnetizing and sheet-forming using a conventional method. In the present invention, further, one surface of the waterproof sheet is made of at least one of the materials described below.
Use one with a coating. As the coating, at least one material selected from polyurethane resin, silicone resin, and fluororesin is used. The coating can also contain various coloring pigments, dyes, extender pigments, and various other additives. The above-mentioned "polyurethane resin" refers to commonly used polyol components such as polyesterol, acrylic polyol, and polyether polyol, as well as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, hexamethylene diisocyanate, or polyvalent isocyanates thereof. It is a resin obtained from a polyisocyanate component obtained from an excess of polyhydric alcohol and a polyhydric alcohol; Also, the above-mentioned "silicone resin" refers to a silicone-modified alkyd resin, a silicone-modified acrylic resin, a silicone rubber, etc.; "Fluorine resin" refers to, for example, a fluorine-containing copolymer (commercially available products such as Lumiflon LF100 and Lumiflon LF100 manufactured by Asahi Glass Co., Ltd.
Specific examples include LF200, Lumiflon LF400, etc.) or a reaction product of the copolymer and the polyvalent isocyanate. In the present invention, the above-mentioned "film" can be formed by, for example, making the various resins into a paint state, and then applying and drying them by a conventional method such as spraying, rolling, or electrostatic coating, or by coating the resin in advance with a film. It can be obtained by molding it into a shape and laminating it with a suitable adhesive. The thickness of the coating is approximately 20 μm to 3 mm. In the present invention, an adhesive is applied to the other surface of the above-mentioned waterproof sheet on which the coating is not formed. However, the adhesive may be a commonly used epoxy resin type, urethane resin type,
It is preferable to use underwater curing adhesives such as those based on polyester resins and acrylic resins. As previously mentioned, the air-adhesive tarpaulin is then brought underwater by a diver and adhered to the surface of an underwater steel structure or to a surface above the water level. During adhesion, the water between the surface of the steel structure and the adhesive is removed by spreading the outer surface of the waterproof sheet by hand or the like along the surface (spreading). As a result, the adhesive exhibits an "initial adhesive action". At that time, by imparting magnetism to the waterproof sheet, it can be completely attached to the surface of the steel structure.
In another embodiment, when the waterproof sheet itself does not have magnetism, the outer surface of the waterproof sheet is held down by a permanent magnet, and the waterproof sheet is attached to the surface of the steel structure by magnetic force. After the initial adhesion is made, the tarpaulin is adhered to the surface of the structure by a compliant adhesive over time. In addition, when the waterproof sheet itself has magnetic force, the fixing effect is further improved by the magnetic force. Thus, according to the method of the present invention, the waterproof sheet will not shift, peel off, or be washed away due to external disturbances such as waves or water flow until the adhesive used is completely cured and exhibits its function. As is clear from the structure of the tarpaulin sheet, it can exhibit sufficient anti-corrosion effects and can prevent deterioration caused by sunlight, making it possible to protect steel structures for a long period of time. becomes. The details of the present invention will be explained below with reference to Examples. Note that "parts" or "%" are expressed as "parts by weight" or "% by weight." Example 1 On one side of a 1 mm thick magnetic sheet obtained by kneading 90% barium ferrite with a particle size of 1 to 5 μm and 10% polyethylene chloride and forming it into a sheet using a conventional method,
The dry film thickness of weather-resistant topcoat paint with the following formulation is
It was spray coated to a thickness of 50 μm and dried for 7 days at room temperature. Then, an anticorrosive underwater adhesive (epoxy resin type) was applied to the other side of the sheet. Next, this was wrapped around the steel pier splash part of the pier and the underwater part, which had been prepared by water sand blasting. At that time, sufficient pressure was applied by hand to eliminate air bubbles and seawater between the substrate and the adhesive.
This was left as it was, and tests and observations were conducted after 12 months. The results are shown in Table 1. (Top coating composition) Fluorine resin [Product name: AP-500, manufactured by Asahi Glass Co., Ltd.: Non-active content: 45%] 30 parts polyisocyanate [Product name, manufactured by Nippon Polyurethane Co., Ltd.: Coronate HL] 5 Titanium oxide 15 Dibutyltin Dilaurate 50×10 ^-6 Xylol 50 100 Example 2 A paint with the following composition was applied to one side of the same magnetic sheet as in Example 1 to a dry film thickness of 50 μm, and after drying, the same as in Example 1 was applied. Construction work was carried out. The test and observation results after 12 months are shown in Table 1. (Top coating composition) Polyisocyanate [Product manufactured by Mitsubishi Chemical Industries, Ltd.:
Mitek GP101A: Non-volatile content 75%] 29 parts Polyester resin [Bayer product name: Desmofene 1100] 9.1 Polyester resin [Bayer product name: Desmofene 800] 9.1 Titanium oxide 20 Xylol 16 Ethyl acetate 6 Butyl acetate 6 Cellosolve acetate 4.8 100 Example 3 One side of the same magnetic sheet as in Example 1 was spray-coated with a paint having the following composition to a dry film thickness of 50 μm, and after drying, the same application as in Example 1 was carried out. The test and observation results after 12 months are shown in Table 1. (Top coating composition) Silicone alkyd resin [Product name: YR3116 manufactured by Toshiba Silicon Corporation: 48% non-volatile component] 50 parts Gobalt dryer 0.03 Lead dryer 0.4 Titanium oxide 10 Precipitating agent 1 Mineral spirit 38.57 100 Example 4 Above A 200 μm thick fluororesin film [tetrafluoroethylene and ethylene copolymer film:
Afrex #200N (trade name, manufactured by Asahi Glass Co., Ltd.) was laminated with an epoxy resin adhesive. Then, construction was carried out in the same manner as in Example 1, and tests and observations were conducted 12 months later. The results are shown in Table 1. Comparative example: Non-magnetic general rubber sheet (thickness 0.6mm)
The work was carried out in the same manner as in Example 1, except that the surface was not coated with paint. The test and observation results after 12 months are shown in Table 1.

[Table] * Measured using an Elcometer adhesion tester.
From the above comparative test results table, it can be seen that the method of the present invention clearly prevents deterioration of the magnetic sheet due to sunlight. As a result, it has become possible to protect underwater steel structures for a longer period of time.

Claims (1)

[Claims] 1. An adhesive is applied in air to the other surface of a waterproof sheet, which has at least one coating selected from polyurethane resin, silicone resin, and fluorine resin on one surface, and then The surface coated with the adhesive is brought into contact with the surface of the underwater steel structure or a wet surface above the water surface, the waterproof sheet is spread over the surface of the underwater steel structure, and the sheet is attached to the surface by magnetic force. A method for protecting a steel structure, characterized by attaching it to the steel structure. 2. The method for protecting a steel structure according to claim 1, wherein the waterproof sheet contains magnetic particles.