JP2007321363A - Painted steel sheet pile excellent in coupling part corrosion resistance and method of manufacturing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel sheet pile having excellent corrosive resistance after placed in a severe corrosive environment such as ocean. <P>SOLUTION: This method is used to apply an effective painting onto a claw fitting part. A claw part and a body portion can have a same corrosive resistance by performing surface treating and integrally thick coating the claw fitting part and the body with an epoxy resin with a high strength. To secure impact resistance equal to or higher than that of a conventional corrosive resistant coating at the body portion to which impact damage is easily given, a thick film protective coating of 1 mm or more is placed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a steel sheet pile that is excellent in corrosion resistance after placement in a severe corrosive environment such as the ocean.

  Heavy duty anti-corrosion steel sheet piles using polyethylene or polyurethane as anti-corrosion coatings are expected to be durable for several decades, so they are used in many cases due to their effectiveness in terms of life cycle costs when used in corrosive environments in rivers and oceans. Has been. When using it, the fitting surface of the joint is hindered from fitting, so heavy corrosion protection cannot be applied and the joint end is coated with a sealant or general coating with anticorrosion specifications different from the main body such as tar epoxy. However, since this work is performed separately from the main body coating, the ground treatment cannot be sufficiently performed, and there is a problem that the anticorrosion property is low. In addition, even if these sealing agents and coatings with general coating are applied to the mating surface, they are easily damaged when mated, and the joint part is corroded to cause peeling from the corroded end. There was a problem.

  In particular, the conventional U-type steel sheet pile has a coating that combines crests and valleys as shown in the cross-sectional view of FIG. 1, and the peeling of the coating progresses due to corrosion due to the large curvature of the claw coating on the crest of the trough. It's easy to do. On the other hand, in the hat-shaped steel sheet pile covering, as shown in the cross-sectional view of FIG. 2, the effect of the part is small because the covering is only in the same shape direction and there is no portion with a large curvature.

  Moreover, as a method for preventing corrosion and peeling progress of the fitting portion, for example, as disclosed in Patent Document 1, there is a method of covering the joint portion after placing a steel sheet pile. However, the cover installation after construction is underwater work, and there is a problem in workability.

JP 2001-131957 A

  The present invention has been made in view of these problems, and its purpose is to provide excellent anticorrosion properties in coated steel sheet piles, and in particular, anticorrosion properties capable of suppressing the progress of peeling from the coated end portion on the joint portion fitting surface. To provide a painted steel sheet pile.

  As for the fitting part of the steel sheet pile claw, since the claws come into contact with each other at the time of placing, a thick anti-corrosion coating of several mm cannot be performed. For this reason, in the conventional heavy anticorrosion coated steel sheet pile, after applying the heavy anticorrosion coating to the claw part, a soft sealant or a thin tar epoxy resin coating is separately applied only to the claw part. A covering example of a U-shaped steel sheet pile coated with a conventional sealing agent is shown in the cross-sectional view of FIG. 3, and a covering example of the hat-type steel sheet pile is shown in the cross-sectional view of FIG.

  As can be seen from FIGS. 3 and 4, the conventional method has a problem that many unpainted portions remain. Furthermore, the surface treatment is not enough to perform the coating separately from the main body, and the coating itself is weak and easily damaged, resulting in corrosion at the nail part and suppressing the progress of peeling of the coating due to corrosion. It was difficult to do. In addition, thick film heavy anticorrosion on the curved surface in the vicinity of the nail has a problem that peeling progress is likely to occur due to stress due to coating film shrinkage and waves due to its complicated shape.

  The anticorrosion coating on the nail fitting part has 1) coating strength and adhesion that does not easily peel off by fitting operation, 2) secures anticorrosion performance with a thin film thickness that can be fitted, and 3) scratches. Even when attached, it is required to have such characteristics that corrosion progress and peeling progress from scratches are small, 4) has weather resistance, and 5) paintability is easy.

  Therefore, as a result of considering the performance required for the claw part and the steel sheet pile main body, chemical conversion treatment or zinc rich primer treatment is performed, and a coating film mainly composed of an epoxy resin as a resin satisfying coating film strength and adhesion is obtained. An anticorrosion film was formed up to the mating surface with an average film thickness of 50 μm or more to ensure the anticorrosion property of the mating claw part. Furthermore, the coating workability and peeling resistance were improved by applying this anti-corrosion specification to the main body at the same time. However, since the impact resistance is important in the steel sheet pile main body, it is also used as a protective coating for conventional heavy-duty protection, and a highly reliable resin such as polyolefin, polyurethane, or polyurea with a thickness of 1 mm or more is used. Impact resistance and weather resistance were ensured by coating on epoxy resin. Depending on the shape of the curved surface of the fitting claw part, the peeling stress may increase, and it is desirable not to form a thick film protective coating on a portion with a large curvature. In that case, in order not to expose the epoxy resin which is inferior in weather resistance, a colored coating film with excellent weather resistance formed by blending acrylic, silicon and fluororesin is formed on the surface, or a film having weather resistance is pasted with an adhesive. It is a thing that secures sex. Thus, if a thick film coating is not used for the nail part, even if the film peels, the peeling stress does not propagate to the thick film coating part of the main body.

The present invention has been made based on the above findings, and the gist thereof is as follows.
(1) In the steel sheet pile, the surface on the side that requires anticorrosion and the fitting surface of the joint portion form a chemical conversion treatment layer or a zinc rich primer layer on the steel sheet pile surface, and the epoxy resin layer as a main component thereon A coated steel sheet pile with excellent anticorrosion properties at the joints, characterized in that the anticorrosion coating layer is laminated with a thickness of 50 to 600 μm.

  (2) The coated steel sheet pile having excellent joint portion anticorrosion properties according to (1), wherein a vertical adhesion force in a flat portion of the anticorrosion coating layer is 5 MPa or more.

  (3) The chemical conversion treatment layer contains phosphoric acid, silica fine particles, magnesium or calcium, or both magnesium and calcium.

  (4) In the steel sheet pile according to any one of (1) to (3), a urethane resin, urea resin, or polyolefin resin of 1 mm or more is further formed on the surface of the anticorrosion coating layer on the surface excluding the fitting surface. A coated steel sheet pile excellent in anticorrosiveness of the joint, characterized by providing a scratch-resistant resin layer of any of the above.

  (5) In the steel sheet pile according to (4), a weather-resistant film is provided on the surface of the anticorrosion coating layer of the fitting surface via one or two weather-resistant coating films or adhesives of acrylic urethane and fluorine resin. A coated steel sheet pile with excellent anticorrosive properties at the joint, characterized by forming

  (6) In the manufacturing method of the steel sheet pile, blasting is performed on the surface on which corrosion prevention is required and the fitting surface of the joint, and then a chemical conversion layer or a zinc rich layer is formed on the surface subjected to the blasting, A method for producing a coated steel sheet pile having excellent anticorrosion properties for joints, characterized in that an anticorrosion coating layer comprising an epoxy resin layer as a main component is laminated thereon with a thickness of 100 to 600 μm.

  The present invention provides a coated steel sheet pile that greatly suppresses the corrosion of the claw portion and the corrosion and peeling from the claw portion when using the steel sheet pile in rivers and oceans, and the painted steel sheet pile includes the claw portion. By applying a thin film anti-corrosion coating or a thick film only to the main body, it is difficult for corrosion to occur on the nails, and even if peeling occurs, there is little effect on the main body. Can be maintained.

  Hereinafter, the present invention will be described in detail.

  First, the steel grade of the steel sheet pile used for the coated steel sheet pile used in the present invention is ordinary steel, steel material with controlled C, Si, Mn and nitrogen, oxygen, or further Cu, Ni, Cr, Mo, Nb, Ti, Shape processing was performed by a hot rolling process using alloy steel to which elements such as Al, Mg, V, and Ca were added. Examples of the shape include a general U shape and a hat shape.

  The coated steel sheet pile of the present invention needs to perform sufficient rust removal work on the painted surface and the claw portion as a pretreatment. A blasting process using a steel grid, steel shot, or sand is generally used for the rust removal work. When rolling damage and corrosion are severe, it is preferable to perform blasting after smoothing the portion with a grinder or the like. When the rust removal work is insufficient, the corrosion resistance is reduced.

  A chemical conversion treatment or zinc rich primer treatment is performed after the pretreatment. The chemical conversion treatment uses an acid-based treatment solution that does not contain chromium in consideration of the environment. In general, an acid containing phosphoric acid is used. As other chemical conversion treatment components, it is preferable to use a treatment liquid containing silica fine particles, magnesium or calcium, or both magnesium and calcium as components. As a method other than the chemical conversion treatment, there is a zinc rich paint containing a large amount of fine zinc powder. Zinc rich paint is roughly classified into inorganic and organic, but organic is advantageous from the viewpoint of adhesion. Organic zinc may be commercially available from paint manufacturers such as Kansai Paint Co., Ltd., Nippon Paint Co., Ltd., and Nippon Steel Chemical Co., Ltd.

  Next, coating with epoxy resin as the main component is carried out up to the fitting surface of the steel sheet pile main body and the claw. With respect to the coating on the nail portion, it is necessary to have a coating property that causes little damage during fitting and is difficult to peel off. It has been difficult to satisfy these required properties with soft resins such as tar epoxy and sealant that have been used in heavy anticorrosion. Epoxy resin has higher coating strength than urethane resin, and has excellent oxygen permeability and adhesion characteristics. Therefore, even with single coating, it ensures oxygen permeability that is equal to or better than that of thick urethane coating. I can do it. As a measure of the strength of the epoxy resin used, it has been found that good results can be obtained from the viewpoint of anticorrosion performance and peel resistance when using a material having an adhesive strength of 5 MPa or more. As the film thickness range of the coating film, the steel sheet pile claw portion needs to have a film thickness that prevents pinholes because the surface is rough (uneven) due to hot working.

  On the other hand, a hard coating film such as an epoxy resin is preferably a thin film coating because peeling stress increases with the film thickness. A thin film is also desirable from the viewpoint of not hindering the fitting. From the above points, a practical average film thickness range of 50 to 600 μm is appropriate. The epoxy resin paint is supplied in either liquid or powder form. As the curing agent for the epoxy resin coating, for example, an amine type is used in the case of liquid and a phenol type is used in the case of powder. When a liquid is used, the steel sheet pile is previously heated to 40 ° C. or higher, and when powder is used, it is heated to 160 ° C. or higher before application. When the temperature of the steel sheet pile cannot be ensured, curing is insufficient and the adhesion strength is insufficient. Therefore, it is difficult to ensure the adhesion force of 5 MPa or more.

  Next, a thick film protective coating is applied to the steel sheet pile main body portion excluding the nail portion on the epoxy resin layer. As the resin to be applied as the thick film protective coating, a resin such as polyolefin, polyurethane, or polyurea is used. Since polyolefin resin is inferior in impact resistance but has great cost merit, a method of coating with powdered polyolefin can be used when a steel sheet pile can be heated at a high temperature of 160 ° C. or higher. On the other hand, polyurethane and polyurea resin are excellent in impact resistance and adhesion, and can be applied at room temperature, so that they are easily applied to large structures. When these resins are used, carbon black is generally added to improve weather resistance. The thickness of these resins is preferably larger in view of the function as a protective coating, and it is desirable to have a film thickness of 1.5 mm or more for polyolefin and 1 mm or more for polyurethane or polyurea resin. The painting range is mainly outside the nail fitting. The curved surface around the nail portion is greatly affected by peeling stress and waves due to the shrinkage of the coating film, and in particular, if the polyolefin resin having a large shrinking stress is applied while avoiding a portion with a large bend, peeling does not easily progress.

  When weather resistance is required for a portion where the thick film protective coating in the vicinity of the nail cannot be applied, weather resistance is secured by applying a colored top coat or colored film on the thick film epoxy coating film. The colored top coat is applied to a thickness of about 30 to 200 μm so as not to interfere with the fitting. Any resin can be used as long as weather resistance can be ensured, but an acrylic or fluorine-based urethane resin is used. In addition, a silicon-based modified resin may be used. As a method other than painting, a weather-resistant film may be attached with an adhesive. As the weather-resistant film, a single layer of vinyl chloride or acrylic resin or a laminate of a plurality of layers is used.

  FIG. 5 shows a cross-section of the fitting claw as an example of a covering structure when the present invention is applied to a U-shaped steel sheet pile, and FIG. 6 shows a cross-section of the fitting claw as an example of a covering structure when applied to a hat-type steel sheet pile. Shown in After the steel sheet pile claw part 1 and the steel sheet pile main body 2 are subjected to rust removal treatment by blast treatment such as sand, grid, shot, etc., the base treatment layer 3 is formed by chemical conversion treatment or organic zinc rich paint. For the ground treatment layer, methods such as spray spray coating, roller coating, and brush coating are used. After the steel sheet pile is heated to an appropriate temperature, the thick film anticorrosive layer 4 mainly composed of epoxy resin is formed with an average film thickness of 50 to 600 μm by liquid spray coating or powder electrostatic coating. After that, only the steel sheet pile main body part 2 is coated with powder polyolefin electrostatic coating of 1.5 mm or more, or two-component isocyanate-cured polyurethane or polyurea resin with a film thickness of 1 mm or more to protect against impact resistance. Layer 5 is formed. Further, when weather resistance is required for the nail portion, a weather-resistant coating film such as acrylic urethane or fluorine-based resin or a film layer 6 having weather resistance is formed on an epoxy resin on which the impact-resistant protective coating 5 is not formed.

  In the present invention, a cross-section of a fitting claw portion is shown as an example of a covering configuration when applied to a hat-type steel sheet pile when a weather-resistant coating film such as acrylic urethane or fluorine-based resin or a film layer 6 having weather resistance is omitted. 7 shows. Since the thick film anticorrosive layer 4 mainly composed of an epoxy resin has a problem in weather resistance, an impact resistant protective layer 5 made of polyurethane or polyurea resin is covered to the tip of the nail.

  The steel sheet pile having a hat-shaped cross section and the fitting claw as a coated steel sheet pile of the present invention are subjected to blasting using a steel grid, and then in Example 1 of the present invention, a chemical conversion mainly composed of calcium phosphate and silica. In the treatment and Invention Examples 2 and 3, an organic zinc (manufactured by Nippon Kayaku Co., Ltd .: NB zinc primer) was applied and dried. After that, the steel sheet pile is heated to 50 ° C, and the paint mainly composed of epoxy resin (Nippon Kasei Co., Ltd .: NSW1500) is applied and cured by spray coating. A polyurethane paint mainly composed of polyol and isocyanate was mixed and sprayed on the surface using a two-component mixed spray coating machine to form an impact resistant protective layer. An acrylic urethane-based colored paint was applied to the surface of the epoxy resin after removing the polyurethane masking of the nail part by brushing to produce the coated steel sheet pile of the present invention. Similarly, the same coating was applied to one peak and one valley of a 5 L-shaped steel sheet pile to produce a coated steel sheet pile of Example 4 of the present invention.

  Moreover, the coated steel sheet pile of the comparative example 1 was manufactured by performing the coating similar to this invention example 3 without applying a chemical conversion treatment or an organic zinc to a base | substrate using a hat-shaped steel sheet pile. As Comparative Example 2, the crest of the hat-type steel sheet pile was similarly subjected to blasting and phosphoric acid-based chemical conversion treatment, and then the epoxy sheeting was applied with a target of 50 μm without preheating the steel sheet pile. After that, thick film urethane resin coating was performed in the range excluding the nail portion.

As Comparative Example 3, a hat-shaped steel sheet pile was formed by combining a conventional heavy-duty steel sheet pile specification chromate and a thin film urethane coating with a 1 mm thin film anti-corrosion layer.
Further, as Comparative Example 4, a conventional heavy anticorrosion coated steel sheet pile was manufactured using one peak and one valley of a U-shaped steel sheet pile. In Comparative Example 4, blasting using a steel grid was applied to the painted surface, then chromate treatment was applied and dried, and then a urethane primer was spray-coated with a 50 μm target and cured, and the nail portion was masked. The anticorrosive layer was formed by mixing and spraying a polyurethane paint mainly composed of polyol and isocyanate on the surface of the main body using a two-component mixed spray coating machine. After removing the nail masking, a urethane rubber-based sealant was applied to the end to produce a conventional heavy anticorrosion coated steel sheet pile.

  In the created hat type, the flanges of the left and right steel sheet piles were cut out to a length of 10 cm from the mountain-painted and valley-painted steel sheet piles, respectively. After sealing the back surface and the cut end surface, the test piece was a state in which the claws were fitted together as a set. As a corrosion acceleration test, a marine tidal zone cycle test was carried out for 90 days, in which drying was performed at 50 ° C. for 3 hours and immersed in 3% saline at 40 ° C. for 3 hours. After the test, the fitting state was removed, and the corrosion state of the claw part and the adhesion deterioration progress distance of the thick film urethane coating from the claw part direction were measured. The evaluation results are shown in Table 1. As apparent from the results in Table 1, in the conventional heavy anticorrosion-coated steel sheet pile of Comparative Example 4, no primer remained at the nail portion and overall corrosion occurred. In addition, the peeling progress distance from the nail part was large, and peeling of 6 mm or more was observed.

  On the other hand, in the coated steel sheet piles of the present invention, the epoxy resin was as thin as 50 μm. In the present invention examples 2 and 3, some rust was observed, but no blisters were generated and the coating film was healthy. Further, the distance of progress of peeling of the thick film urethane resin from the direction of the nail portion remained at about several mm.

  In Comparative Example 1, the ground treatment of the present invention is omitted, but it can be seen that the swelling of the coating film and the occurrence of rust are accelerated when there is no ground treatment. In addition, when the strength of the epoxy resin is not sufficient as in Comparative Example 2, rust and swelling of the coating film are likely to occur.

Sectional drawing at the time of connecting a U-shaped steel sheet pile. Sectional drawing at the time of connecting a hat-type steel sheet pile. An example of the cross section of the fitting part used with the conventional U-shaped heavy anticorrosion coating steel sheet pile is shown. An example of the cross section of the fitting part of the conventional hat-type heavy anticorrosion coated steel sheet pile is shown. An example of the covering composition sectional view of the joint of the painting U type steel sheet pile of the present invention is shown. An example of the covering composition sectional view of the joint of the paint hat type steel sheet pile of the present invention is shown. An example of the covering composition sectional view of the joint of the paint hat type steel sheet pile of the present invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Claw part of steel sheet pile 2 Steel sheet pile main-body part 3 Chemical conversion treatment or zinc rich base treatment 4 Thick film anticorrosive layer which has an epoxy resin as a main component 5 Protective coating layer 6 Weather-resistant colored coating or film 7 Chromate chemical conversion treatment 8 Thin film primer treatment 9 Anticorrosion layer 10 Sealant

Claims (6)

  In steel sheet piles, the surface on the side that requires corrosion prevention and the fitting surface of the joint part form a chemical conversion treatment layer or zinc rich primer layer on the steel sheet pile surface, and an anticorrosion coating mainly comprising an epoxy resin layer thereon. A coated steel sheet pile with excellent anticorrosive properties at the joint, characterized in that the layers are laminated to a thickness of 50 to 600 μm.   The coated steel sheet pile excellent in anticorrosiveness of the joint portion according to claim 1, wherein a vertical adhesion force in a flat portion of the anticorrosion coating layer is 5 MPa or more.   The said chemical conversion treatment layer contains phosphoric acid, silica fine particles, magnesium or calcium, or both magnesium and calcium, The coated steel sheet pile excellent in the joint part anticorrosion property of Claim 1 characterized by the above-mentioned.   The steel sheet pile according to any one of claims 1 to 3, wherein the surface of the anticorrosion coating layer on the surface excluding the fitting surface is further scratched by any of urethane resin, urea resin, and polyolefin resin of 1 mm or more. A coated steel sheet pile excellent in anticorrosiveness of the joint, which is provided with a prevention resin layer.   The steel sheet pile according to claim 4, wherein a weather resistant film is formed on the surface of the anticorrosion coating layer of the fitting surface via one or two weather resistant coating films or adhesives of acrylic urethane and fluorine resin. Painted steel sheet pile with excellent anticorrosion properties for joints.   In the steel sheet pile manufacturing method, blasting is performed on the surface that requires anticorrosion and the fitting surface of the joint, and then a chemical conversion treatment layer or a zinc rich layer is formed on the surface subjected to the blasting treatment, and further thereon A method for producing a coated steel sheet pile excellent in anticorrosive property of a joint, characterized by laminating an anticorrosion coating layer comprising an epoxy resin layer as a main component in a thickness of 50 to 600 μm.