JPH0790204B2 - Anticorrosion method for steel structures - Google Patents

Description

The present invention relates to a method for efficiently anticorrosion coating a steel structure, particularly a steel structure constructed in a harsh corrosive environment such as the ocean or a river and in a body of water with a fast water flow. Regarding

Recently, various steel structures (for example, long bridges, pipelines, subsea bases, oilfield excavation equipment, port facilities, etc.) are being constructed,
Or it is about to be built. Such a steel structure is always submerged in water, a tidal part that may or may not be submerged in the water due to the ebb and flow of the tide, a splashing part where splashes of water wave and more However, the corrosive environment at each part is not the same, and how to apply excellent anticorrosion treatment to these parts becomes an important issue. The present invention relates to a method particularly useful for corrosive construction of such a steel structure from a submerged portion to a splash portion (called an underwater portion). In particular, the splashed portion is more likely to corrode than others, and it is also difficult to prevent galvanic corrosion.

Conventionally, corrosive construction of underwater parts in new and existing steel structures has been carried out, for example, by a diver diving and manually applying an underwater curing type anticorrosive paint. However, scaffolding conditions are extremely poor in the underwater portion, and in a water area where water flows quickly, the underwater curable coating composition often peels off before it is cured, which is inefficient. In order to improve these, it has already been proposed to fix a wire mesh etc. to the anticorrosion construction part in advance and to apply the underwater hardening type anticorrosive paint so that it adheres to the steel structure surface through the stitches of this wire mesh. The coating workability in severe water was not practically sufficient.

This fact is not limited to marine structures, but to a certain extent even in steel structures constructed in rivers, lakes, etc.
There are similar problems as above. Therefore, there is a strong demand for the provision of an efficient anticorrosion construction method for the underwater portion of these steel structures.

Therefore, the present inventors have examined the method of applying anticorrosion treatment to the underwater portion by on-site construction, and filled a box with a specific shape and inner surface with a specific anticorrosion paint, and then treated it with anticorrosion. The present invention was completed by finding that all of the above defects can be eliminated by fixing the anticorrosion paint on a surface and curing the anticorrosion paint, and then removing the box.

That is, the present invention, in accordance with the surface shape of the steel structure surface for anticorrosion construction, and inside the box formed by the release treatment of the inner surface, an epoxy resin component of 20,000 poises (25 ° C) or more and 10,000 poises ( Steel that is filled with a two-component type reaction-curable solventless epoxy resin anticorrosive paint containing a curing agent component of 25 ° C. or higher as a main component, and then this box is subjected to anticorrosion by the anticorrosion paint filled in the box. The present invention relates to an anticorrosion method for a steel structure, which comprises fixing the steel structure so as to be in contact with the surface of the structure, curing the anticorrosion paint filled in the box body, and then removing the box body.

The steel structure subjected to the anticorrosion treatment according to the present invention is mainly affected by the underwater portion (the portion from the submerged portion to the splash portion) and water (including seawater). And even if it is a repair of an existing steel structure or a new installation, as a pretreatment of the anticorrosion construction site, if the occurrence of rust, such as insects, shellfish, algae, etc. is observed, remove it It is preferable to set.

The surface shape of the steel structure that can be subjected to anticorrosion construction by the method of the present invention is not particularly limited, and for example, flat surfaces, protrusions such as bolts and nuts, corners, corners, spheres, linear portions, end face portions, etc. The shape may be one or a combination of two or more.

In the present invention, the box body is used to efficiently form the anticorrosion paint layer on the anticorrosion construction part of the underwater part of the steel structure without being washed away by the flow of water or the like. That is, the box filled with the anticorrosion paint is submerged in water so that the filled anticorrosion paint is in contact with the anticorrosion treated surface of the steel structure, and when fixed, not only the flat surface of the anticorrosion treated surface of the steel structure but also other Since the anticorrosive paint can be evenly and efficiently coated evenly on the shape surface of the box and the box body is fixed, the anticorrosive paint filled in the box does not peel off even in a violent water area. Then, after the textile coating material is almost or completely cured, the box body is removed, and the anticorrosion coating film layer is firmly adhered and formed on the surface of the steel structure subjected to the anticorrosion treatment.

Therefore, the box body may have any shape and size that can be filled with the anticorrosive paint and can cover a part or the whole of the anticorrosion treated surface of the steel structure. Specifically, it is said that the box shape along the unevenness of the steel structure surface effectively uses the anticorrosion paint so that the anticorrosion paint coating layer with a thickness of 1 mm or more can be formed on the anticorrosion treated surface Although preferred from the point of view, in the present invention, when the box body is covered, it may be a cube or a rectangular parallelepiped in which the distance between the top of the convex portion of the steel structure and the inner surface of the box is 1 mm or more. .

Also, since this box body is removed after the filled anticorrosion paint is cured, it is not preferable that the anticorrosion paint adheres to the inner surface of the box. Therefore, the inner surface of the box is subjected to a mold release treatment to prevent them. There is a need. The mold release method is
The method is not specifically limited, but specifically includes the following methods.

(1) Adhesive is applied to an adhesive tape that has been back-treated with a release agent such as silicone resin or wax.

(2) A paint containing a lubricant such as silicone oil, olefin oil, diester oil, polyethylene wax, and fluid paraffin in an amount of 1 to 60% by weight is applied.

(3) γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane,
Vinyltrichlorosilane, N-β (aminoethyl) γ-
Apply a silane coupling agent such as aminopropyltrimethoxysilane.

(4) A composition comprising an organopolysiloxane resin and an alkali metal compound as main components and, if necessary, liquid paraffin or solid paraffin is coated (JP-A-59-25868 and JP-A-60-206888). ).

(5) A composition containing a polymer containing a perfluoroalkyl group-containing (meth) acrylic monomer as a main component and further containing an alkali metal compound if necessary is coated (JP-A 61-23656, Same-23657, Same-95078, Same-9507
7).

(6) A composition containing an organopolysiloxane resin and an alkali metal compound as main components (JP-A 61-51069).

(7) A composition containing an alkali metal compound and a hydrophobic silicon compound (Japanese Patent Laid-Open No. 61-57659) is applied.

(8) Cover with polyethylene or vinyl film or sheet.

The material of the box body is not particularly limited, and examples thereof include metal, plastic, and wood. In addition, it is preferable that one or more side surfaces of the box body be openable / closable so that the box body can be easily removed after the anticorrosion paint is cured.

Next, as the anticorrosive paint to be filled in the box body, the underwater curing type two-component solventless epoxy resin paint exhibiting excellent anticorrosion property under the severe environment is used.

This is a two-part type that mixes the resin component and the curing agent component uniformly during use, and the pot life is limited (about 2 hours at 20 ° C), so immediately after mixing both components. Filling is preferred. In this paint, for example, the resin component is preferably 20,000 poise / 25 ° C or higher, and the curing agent component is preferably 10,000 poise / 25 ° C or higher. As the epoxy resin of the resin component, a semi-solid or liquid at room temperature,
Particularly preferred are those having at least two epoxy groups in one molecule, having an epoxy equivalent of about 140 to 400 and a molecular weight of about 500 or less.

Specifically, one or more aromatic di- and poly-glycidyl ethers are considered to be suitable for maintaining curability, adhesion and coating strength, and if necessary, aliphatic epoxides and oils. The flexibility and adhesion of the coating film are adjusted by adding a ring compound epoxide or the like. Specific examples of aromatic glycidyl ethers include bisphenol A type epoxy resins (for example, Ciel Chemical Company Epicoat 828, Epicoat 834, Dow Chemical Company DER331, DER337, etc.), bisphenol F type epoxy resins (eg Dainippon Ink and Chemicals, Inc.). Chemical industry companies such as Epicron 830 and Epicron 850), and aromatic polyglycidyl ethers include novolac epoxy resins (for example, Dow Chemical Company DEN431 and DEN438). As the curing agent component, a water-soluble polyamine or an amine adduct is avoided, and a polyamine or an aminopolyamide resin that is as hydrophobic as possible to react with an epoxy group at room temperature can be used. For example, laccamide 9-263 manufactured by Dainippon Ink and Chemicals, Inc., Fuji Kasei Kogyo Co., Ltd. Thomaid 2
55, thoramide 205L, modified heterocyclic diamine, etc. Furthermore, in order to accelerate the curing reaction in water,
If necessary, triphenyl phosphite, phosphates and the like can be appropriately used, and a thickener (for example, asbestos), an extender pigment (for example, talc, silica sand,
Quartz stone powder, mica, etc., color pigments (yellow lead, red iron oxide,
Carbon black etc.) is used as necessary for adjusting the viscosity. This paint cures easily in water.

In the anticorrosion method according to the present invention, first, the inside of the box is filled with an anticorrosion paint. The size of the box varies depending on the steel structure to be subjected to anticorrosion treatment, but it is preferable that it is easy to handle in water and manually. Although the shape of the anticorrosion treated surface also varies depending on the shape of the anticorrosion treated surface, any shape may be used as long as the anticorrosion coating layer is uniformly formed on the irregularities, corners, edges and the like of the treated surface.

Next, the box body filled with the anticorrosion paint is pressed against the anticorrosion treated surface in the underwater portion of the steel structure, mainly in water so that the anticorrosion coating comes into contact with the anticorrosion treated surface. If the flat surface or the surface of other shape is uniformly covered and the box is fixed in water as it is, the anticorrosion paint layer inside the box is reactively cured without flowing out due to the flow of water. Since the inner surface of the box has been subjected to a mold release process, the box body can be easily removed after the anticorrosion paint has been cured by reaction, and as a result, the steel structure's anticorrosion treated surface is separated by the flow of water etc. Without doing so, the reaction-cured anticorrosion coating layer is uniformly formed.

The method of fixing the box in water is also not particularly limited, and depends on the shape and size of the steel structure and box, but for example, use a clamp or wedge to fix it, or tie it with rope or wire. It is also possible.

The anticorrosion method of the present invention is particularly preferably carried out in water with a fast water flow. For example, if a bridge pier is constructed in the ocean area, the anti-corrosion coating of the bridge pier and the underwater parts such as the buffers installed around it will cause the tidal current in the vicinity to reach 9 knots (about 16.6 km / h) and add swell. In the conventional coating method, the coating film was often washed out before it was cured in water, but in the present invention, the box body is filled with the anticorrosive paint, and the box body is fixed until the paint is cured. Therefore, the anticorrosion paint will never flow out.

Further, in the present invention, the box body used for fixing is removed, and since the anticorrosion property is expressed only by the anticorrosion paint, the anticorrosion paint layer can be formed into a continuous film without gaps, and the box body can be repeatedly used. So it was extremely economical.

Example 1 Bolt joint of H-section steel submerged in the sea (corrosion protection area
30-50 cm, bolt height 2 cm), underwater curing type two-component epoxy resin anticorrosion paint (resin content 35000 poise / 25 ℃,
Polyamide 16000 poise / 25 ° C, Kansai Paint Co., Ltd., trade name Napco Barrier-N equivalent product, filled with a uniform mixture and filled with a box body (the inner surface is adhesive tape back treated with a release agent. Yes, size 35 × 35 cm, depth 3.5c
m) was crimped so that the anticorrosive paint was in contact with the bolt joint and fixed with a clamp. The tidal current in this area was about 9 knots and the swell was severe, but the crimped box did not flow out. When the box was removed after about 2 hours, the epoxy resin paint with excellent anticorrosion properties was hardened to a strong thickness at the bolt joint and firmly adhered to it, and it did not peel off due to the tidal current.

Claims (1)

[Claims] 1. A box body formed according to the surface shape of a steel structure surface for anticorrosion construction, and having an inner surface subjected to a mold release treatment,
Filled with a two-component reaction-curable solventless epoxy resin anticorrosive paint mainly composed of an epoxy resin component of 20000 poise (25 ° C) or more and a curing agent component of 10,000 poise (25 ° C) or more, and then this box body Is fixed to the steel structure such that the anticorrosion paint filled in the box is in contact with the surface of the steel structure to be subjected to anticorrosion construction, and the anticorrosion paint filled in the box is cured by reaction, A method for preventing corrosion of a steel structure, which comprises removing