JPS60230849A - Method of coating steel sheet pile - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a method for coating steel sheet piles, and more particularly, to a method for coating steel sheet piles by forming a coating layer having excellent anticorrosion performance on the surface of the steel sheet piles. It is.

[Background of the invention] Conventionally, steel sheet piles for civil engineering and construction have been used for the purpose of protecting rivers, coasts, ports, etc. by driving a large number of steel sheet piles into the ground continuously to form protective shelves, or for construction purposes. It has been used for the purpose of fixing the ground at dredging sites, etc., and preventing mixed paper from flowing into the work site or collapsing.

These steel sheet piles are exposed to water such as river water, wastewater, rainwater, and seawater, the atmosphere, and sunlight in the outdoor natural environment.
In addition, since they come into direct and strong contact with earth, sand, mud, and debris, corrosion is extremely likely to occur.Especially in environmental places where running water, waves, etc., and the atmosphere and sunlight affect mating, such as ports and estuaries, the above-mentioned Severe corrosion occurs, but until now no effective corrosion prevention measures have been taken.

Therefore, even if conventional steel sheet piles are made of highly corrosion-resistant steel materials, they are susceptible to corrosion in the aforementioned natural environment, and their durability is relatively short, resulting in long-term (for example, for about 20 years or more).

Conventionally, in order to prevent corrosion of steel sheet piles, inorganic zinc paints and tar/epoxy resin paints were used.

FRP coating layers made of epoxy resin or unsaturated polyester resin have been used, but these have poor mechanical strength, long-term durability, and economical efficiency (especially workability and productivity during coating). In this respect, it is one of the most effective anti-corrosion coating methods.

[Summary of the Invention] As a result of studying a coating method for steel sheet piles that can economically and industrially produce anti-corrosion-coated steel sheet piles with high anti-corrosion effects and high durability, the inventors found that By coating or adhering to the surface of steel sheet piles to form a molten and softened polyolefin layer, and then applying pressing pressure to the molten and softened polyolefin layer, the coating operation is repeated multiple times. The inventors have discovered that it is possible to industrially manufacture steel sheet piles having an excellent anti-corrosion coating layer by forming a thick anti-corrosion coating layer consisting of multiple layers of polyolefin on the surface, and have completed this invention.

That is, this invention provides: (1) By applying or adhering powder polyolefin to the surface of the steel sheet pile that has been heated to a temperature at least 10oC higher than the melting temperature of the powder polyolefin used as a coating material, (2) forming a polyolefin layer in a molten and softened state with a uniform thickness; Step of forming a covering layer.

and (3) a step of performing the steps (1) and (2) above one or more times on the surface of the polyolefin anticorrosion coating layer formed by the above (2). The present invention provides a method.

In other words, this invention is a method for coating steel sheet piles with complex surface shapes used in civil engineering and construction, which has not been done in the past. The present invention provides a novel coating method called "coating".

The coating method of the present invention can easily and reproducibly form a thick, excellent anti-corrosion coating layer on each surface of steel sheet piles having various surface shapes by repeating a relatively simple process. This is an extremely productive coating method.

The anti-corrosion coated steel sheet pile produced by the coating method of the present invention does not have voids or air bubbles inside the thick anti-corrosion coating layer, and has stable mechanical strength, durability, anti-corrosion properties, etc. It is a steel sheet pile for civil engineering and construction that has a thick and excellent anti-corrosion coating layer made of multiple layers of polyolefin, and is useful for extremely long periods of time when installed on coasts, ports, rivers, irrigation ponds, etc. This is an excellent anti-corrosion coated steel sheet pile that exhibits excellent corrosion resistance.

[Detailed Description of the Invention] This invention will now be described in more detail with reference to the accompanying drawings.

Figure 1 shows a state in which a large number of steel sheet piles according to the coating method of the present invention are successively driven into the ground in order, and the steel sheet piles are connected and driven to form a protective shelf. FIG. 2 is a perspective view showing an example, and FIG. 2 is a sectional view showing a cross section of a first-stage protective shelf.

FIG. 3 is a perspective view showing an example of a steel sheet pile used in the coating method of the present invention.

FIG. 4 is a plan view schematically showing an example of the main steps in the coating method of the present invention.

FIG. 5 is a sectional view showing a cross section of an example of a steel sheet pile manufactured by the coating method of the present invention.

In the coating method of this invention, as shown in FIG.
(A) A preheating furnace (electric furnace, gas burner furnace, etc.) to a temperature at least 10'C higher than the melting temperature of the powdered polyolefin used for coating the steel sheet pile 2, preferably about 20 to 250°C higher. For applying or adhering powdered polyolefin (spraying,
Equipment for spraying, electrostatic coating, fluidized dipping, thermal spraying, etc.6
Then, (B) apply pressure to the molten and softened polyolefin layer formed on the steel sheet pile using an appropriate pressure tool (not shown in the drawing). ), preferably the average thickness of the coating layer is about 0.02 to 2.0 mm, especially 0.05 to 1.0 mm
．． Applying or adhering the powdered polyolefin in (A) so that the thickness is about 0 mm, and (
B) The pressing of the polyolefin layer on the steel sheet pile is carried out by repeating the coating operation at least multiple times, and finally the coating layer is cooled to approximately room temperature to form a thick layer made of multiple layers of solidified polyolefin. an anti-corrosion coating layer (preferably the average thickness of the layer is about 0.8-5 mm, especially 1.0 mm)
3 mm).

Specific embodiments of the coating method of the present invention include: (a) Applying or adhering adhesive powder polyolefin directly to the surface of a steel sheet pile, heating and softening it, and then applying the adhesive powder to the formed layer. A method of applying pressing pressure and repeating these operations to form a thick anti-corrosion coating layer made only of the adhesive powdered polyolefin. (b) Applying or adhering the adhesive powdered polyolefin to the surface of the steel sheet pile and heating it. - Softened and relatively thin adhesive layer (thickness approximately 0.02 to 2.0 mm, @0.03 to 1
．． 0 mm), and then coating or adhering non-adhesive powder polyolefin on the layer and applying pressing pressure multiple times.
A method of forming a thick outer layer of the anti-corrosion coating layer by repeating the steps to form a thick anti-corrosion coating layer consisting of two types of layers, and (c) as shown in FIG. 4
After preheating the steel sheet pile 10, the surface of the pretreated steel sheet pile 10 is coated with the above-mentioned (a).
) or (b) to form a thick anti-corrosion coating layer consisting of various layers.

The powder polyolefin (non-adhesive powder polyolefin or adhesive powder polyolefin) used in the coating method of the present invention has a melting temperature of about 50 to 2
50°C, particularly preferably in the range of 60 to 230°C, and has a melt index of about 0.1 to 60 g/10
Any powder polyolefin (in particular, an ethylene polymer or copolymer) having an average particle size of about 35 to 300 mesh (Tyler sieve) obtained from a polyolefin of about 100 ml may be used.

The powdered polyolefin of the first stage preferably has an average particle diameter of about 35 to 300 mesh as described above. If the particle size of the powder is much larger than 35 mesh, it may not be possible to obtain a homogeneous and strong coating layer. If the powder is much smaller, the fluidity of such powder may not be sufficient and it may not be possible to uniformly coat the surface of the steel sheet pile by normal means.

Furthermore, the powdered polyolefin used in the coating method of the present invention has, in addition to the above-mentioned properties, the ability to adhere to steel materials and/or corrosion prevention properties such as high weather resistance and environmental stress cracking resistance. It may be.

The coating method of the present invention has the excellent advantage that it is not necessary to provide an adhesive layer on the surface of the steel sheet pile to be coated by using only the powdered polyolefin that has adhesive properties to the steel sheet.

In addition, in the coating method of the present invention, when using powdered polyolefin that does not have adhesive properties to steel plates but has anti-corrosion properties such as high weather resistance and environmental stress cracking resistance, it is necessary to pre-coat the steel plate. For example, about 50 to 2
Provided with a hot-melt type adhesive layer with a bonding temperature in the range of 50°C, especially 60-200'C;
Alternatively, it is suitable to provide a layer of another adhesive primer in order to ensure strong adhesion of the non-adhesive polyolefin to the surface of the steel sheet pile to be coated.

In this invention, first, as shown in FIG. The surface of the steel sheet pile is preheated to a temperature within the range of 300°C, and a coating or adhesion device 6 is used to apply powdered polyolefin (especially powdered polyethylene, etc.) by fluid dipping, electrostatic coating, or thermal spraying. The powdered polyolefin layer formed on the surface of the steel sheet pile is immediately coated by applying it to the portion of the surface of the preheated steel sheet pile to be coated using a four-stage method such as a method, a blowing method, or a sprinkling method. Mainly, there is a method (operation A) in which the sheet pile is melted and softened by the heat of the steel sheet pile to form the polyolefin layer 11 in a melted and softened state, and then powdered polyolefin is applied or attached.

In this invention, as described above, after applying or adhering the powdered polyolefin to the surface of the preheated steel sheet pile, if necessary, the portion of the coating layer 11 after application and adhesion is removed as shown in FIG. As shown in the figure, the polyolefin is heated again to a sufficient temperature in the post-heating furnace 7 to be remelted, and a pressing force is applied to the molten and softened polyolefin coating layer 11' using an appropriate pressing tool. . (B Operation) In the coating method of the present invention, the coating operation consisting of the above-mentioned (A) application or adhesion operation of powdered polyolefin and (B) operation for pressing the polyolefin layer on the steel sheet pile is preferably carried out at least multiple times. Repeat 2 to 10 times,
Finally, the coating layer 11' is cooled to room temperature by a known means (for example, water cooling method, air cooling method, cooling roll method, etc.), and the fifth coating layer 11' is cooled to room temperature.
As shown in the figure, the steel sheet pile 2 has a thick anti-corrosion coating layer 8 made of multiple layers of cooled and solidified polyolefin.

In the coating method of the present invention, in the above-mentioned operation CB), each molten and softened polyolefin layer, which becomes the coating layer on the steel sheet pile, is pressed down along the surface of the steel sheet pile by external pressing pressure. Yes 1 For example, to attach an appropriate heat-resistant presser foot, sequentially press down with a device (for example, a presser foot with a metal roll or an elastic rubber roll, a tool with a presser iron, a belt or sheet with a presser foot, etc.),
Alternatively, it is preferable to press with a mold that matches the shape of one side of the steel sheet pile. The above pressing device may also serve as a heating or cooling device.

In the coating method of the present invention, it is particularly important to repeat the coating operations (A) and (B) described above, and by repeating these operations multiple times, the initial preheating temperature of the steel sheet pile can be kept relatively low. It is possible to substantially prevent the formation of air bubbles in the coating layer and to stably form a homogeneous and thick coating layer, or to provide a steel sheet pile with a coating layer that is sufficient for corrosion protection of the steel sheet pile. It is possible to achieve the effect that the bonding can be performed.

Examples of the polyolefin used as a raw material for the powder polyolefin used in the coating method of the present invention include homopolymers or copolymers of monomers such as ethylene, propylene, 1-butene, and 1-pentene (for example, olefins such as ethylene or propylene). and a copolymer with a vinyl monomer copolymerizable with them), and these can be used either alone or in the form of a mixture.

Examples of the adhesive powder polyolefin include (i) adhesive polyolefin obtained by reaction, such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-acrylic acid copolymer; α, β-impounds are added to polyolefins such as polymers, ethylene-maleic acid co-Φ0 polymers, ethylene-maleic anhydride graft copolymers, ethylene-glycidyl methacrylate-vinyl acetate terpolymers, and ionomer polymers. A copolymer obtained by conventional copolymerization or graft copolymerization of saturated carboxylic acid or its ester, its anhydride or its metal salt, or saturated organic carboxylic acid; (11) polyolefin and (i) adhesive polyolefin (iii) Adhesive compositions in which polyolefin is blended with a tackifier, etc.; and (1v) polyolefins in which a rubber component is mixed to give adhesive properties; and (V) polyolefins in which peroxide is added. Examples include powdered polyolefins that are heat-fusible adhesives (hot-melt type adhesives, etc.) obtained from compositions that are mixed to give adhesive properties.

The adhesive powder polyolefin can be used as described above (a) when forming a thick anti-corrosion coating layer consisting only of adhesive powder polyolefin on the surface of a steel sheet pile; (C) When forming two thick anti-corrosion coating layers consisting of an anti-corrosion layer and an anti-corrosion non-adhesive layer, or (C) the above-mentioned (a)
) or (b) can be used to form various thick anti-corrosion coating layers, and retains appropriate elasticity or flexibility after either coating.
It can act as a heated adhesive layer without becoming too hard or brittle, and has a high adhesive strength (180 degree peeling, tensile speed 10 mm/min, 2
0°C) is about 2 K, g/'cm or more, especially 4-2
It is suitable that it is about 0 Kg/cm.

Furthermore, in order to impart high weather resistance to each of the above powdered polyolefins, it is necessary to add zero
．． Powder may be produced from a composition obtained by adding additives, mainly stabilizers, in an amount of about 0.01 to 5.0% by weight. The stabilizer may be selected from known antioxidants such as sterically hindered phenolic antioxidants, phosphoric antioxidants, sulfur-containing antioxidants, and amine antioxidants; Use alone or in combination. The most preferred of these antioxidants are sterically hindered phenolic antioxidants and sulfur-containing antioxidants, specific examples of which include 2,6-tert-butyl-4-methyl. Phenol, 2,2-methylene-bis-(6-tert-butyl-methylenephenol), 4,4'-thiobis-(3-methyl-1゜6
-tert-butylphenol), 4,4-thiobis-(2-tert-butyl-5-methylphenol)
, distearyl disulfide, and the like. Note that the weather-resistant polyolefin composition may appropriately contain other additives in addition to stabilizers such as antioxidants.

In this invention, the powdered polyolefin applied or attached to the surface of the steel sheet pile contains, in addition to the above-mentioned components, an inorganic filler such as talc, calcium carbonate, silica, alumina, mica, and carbon black, or an antioxidant. Additives such as additives, colorants, and softeners; and corrosion inhibitors such as metal chromates, metal phosphates, metal phosphites, metal borates, molybdates, and metal nitrites. Inorganic corrosion inhibitors such as metal salts of aromatic carboxylic acids, aliphatic or aromatic compounds having a plurality of hydroxyl groups, and organic corrosion inhibitors such as tannic acid may be added as appropriate.

In the coating method of the present invention, the multi-layer thick anti-corrosion coating layer formed from the powdered polyolefin described above has a tensile strength of 50 to 300 after being coated on the surface of the steel sheet pile.
Kg/cm'teatte, impact resistance (per thickness lmm) measured by ASTM-G14 is 10 to 200 Kg1
about 0.3-5 mm, especially 0.5-3
It is preferable to have a protective layer with a thickness of 1.0 mm as at least the main layer, but the above-mentioned polyolefin and various other additives and compounding agents can also be used as a protective layer with such performance. It is preferable that a polyolefin composition, particularly a polyethylene polymer composition, which has been appropriately selected and blended and prepared from the following, is made into a powder polyolefin by a known mechanical or chemical method and used in the coating method of the present invention.

The steel sheet pile used in the coating method of the present invention is generally used for civil engineering and construction, and is designed to form grooves with a small inner diameter along both side edges of the main body of the steel sheet pile. The steel sheet pile may have any shape and size as long as it has a joint portion that is bent outward.

As shown in Figure 3, a typical steel sheet pile has a main body with a roughly U-shaped cross-sectional structure, and the rising parts (sometimes called flanges) on both sides have small inner diameters. An example is a long steel plate structural member (steel sheet pile 2) each having joint portions 3 bent outward to form a groove shape.

The steel sheet piles 2 are connected by the joints 3 on the rising parts on both sides of the steel sheet piles 2, as shown in Figure 2, and the individual steel sheet piles are successively lined up and driven into the ground, so that a large number of steel sheet piles are connected. It is used to form a protective shelf l which is cast as shown in FIGS. 1 and 2. In such a protective shelf, as shown in FIG. 2, it is sufficient that at least one side of the protective shelf l on the side exposed to seawater, river water, etc. is provided with an anticorrosive coating layer.

Note that the cross-sectional shape of the steel sheet pile does not necessarily have to be as shown in Figure 2; for example, it may be almost straight, Z-shaped, S-shaped, H-shaped, etc. Good too.

The steel sheet pile, which has a main body with a roughly U-shaped cross-sectional structure shown in Figure 3, is made of steel plates with a thickness in the range of about 5 to 30 mm, and a width of about 200 to 800 mm. There it is,
It is sufficient that the height of the rising parts on both sides is about 50 to 300 mm, and the length is about 2 to 30 m. Other steel sheet piles also have the main sizes as described above. If so, that's fine.

In the coating method of the present invention, the steel sheet pile to be coated with powdered polyolefin may have a stone contact layer on the surface to be coated, but the adhesive layer is preliminarily applied to the surface of the steel sheet pile. method (adhesive application method, adhesive dipping method, adhesive spraying method, etc.), or almost simultaneously or immediately before the powder polyolefin coating in the covering power method of this invention. A softened or liquid adhesive layer may be formed by extruding or applying the adhesive onto the surface to be coated.

Note that the steel sheet pile used in the coating method of the present invention has been subjected to some kind of surface treatment in advance, prior to the coating operation with the powdered polyolefin described above, to improve its resistance to corrosion. It may be something. In other words, steel sheet piles.

Prior to the coating operation, it is preferable that mill scale, red rust, dirt, etc. on the surface of the steel sheet pile be removed by shot blasting, sandblasting, pickling, etc. Also, the surface of the steel sheet pile should be coated with powdered polyolefin or Prior to adhesion and anti-corrosion coating, as shown in Figure 4,
If the surface of the steel sheet pile is subjected to pretreatment such as chromic acid treatment, phosphoric acid treatment, and/or epoxy resin primer coating in the pretreatment tank 5, the adhesion and anticorrosion properties of the anticorrosive coating layer will be further improved.

- The coating method of the invention can also continuously supply steel sheet piles and continuously form an anti-corrosion coating layer on the surface of the steel sheet piles, and can also provide a steel sheet pile having a thick and excellent anti-corrosion coating layer. This is a coating method for steel sheet piles that can be manufactured with high productivity.

The anti-corrosion coated steel sheet pile obtained by the coating method of the present invention is, for example, as shown in FIG. Since the anti-corrosion coating layer 8 made of polyolefin is formed on the steel sheet pile, it has extremely excellent impact resistance, weather resistance and durability against the natural environment, and when the steel sheet pile is driven into the ground, it is It can sufficiently resist the impact and erosive force of strong adhesion to stones, gravel, gravel, etc., or the impact and erosive forces of river water, seawater, and even drifting objects.
The polyolefin layer is directly on the surface of the steel sheet pile or in close contact with a pre-treated coating layer to protect it, and the surface of the steel sheet pile is not brought into direct contact with water, sudden air, or sunlight, I don't let them be exposed.

For example, as shown in FIG. 1, a large number of steel sheet piles 2 having anti-corrosion coating layers formed by the coating method of the present invention are successively and sequentially driven into the ground (ports, rivers, coasts, etc.).
When these steel sheet piles are connected and installed to form a protective shelf, a high level of corrosion protection performance can be achieved for a long period of time (for example, about 20 years or more, especially about 30 years or more). It shows.

[Brief explanation of drawings]

Figure 1 shows a state in which a large number of steel sheet piles according to the coating method of the present invention are successively driven into the ground in order, and the steel sheet piles are connected and driven to form a protective shelf. FIG. 2 is a perspective view for illustrating an example, and FIG. 2 is a cross-sectional view of the protective shelf. FIG. 3 is a perspective view showing an example of a steel sheet pile used in the coating method of the present invention. FIG. 4 is a plan view schematically showing an example of the main steps in the coating method of the present invention. FIG. 5 is a sectional view showing a cross section of an example of a steel sheet pile manufactured by the coating method of the present invention. 1: Protective shelf, 2: Steel sheet pile, 3: Joint part, 4: Preheating furnace, 5
: Pre-treatment tank, 6 Equipment for coating or adhering powdered polyolefin, 7: Post-heating furnace, 8° 11.11' 2 (Anti-corrosion) coating layer. Figure 1 Figure 3

Claims (1)

[Claims] 1. (1) By applying or adhering powdered polyolefin to the surface of a steel sheet pile that has been heated to a temperature at least 10°C higher than the melting temperature of the powdered polyolefin used as the coating material, Step of forming a polyolefin layer in a molten and softened state with a uniform thickness on the surface 1 of the steel sheet pile, (2) By applying pressure on the polyolefin layer in a molten and softened state in L, the surface of the steel sheet pile is (3) forming a polyolefin anti-corrosion coating layer integrally joined on the surface of the polyolefin anti-corrosion coating layer formed in (2) above;
1. A method for coating steel sheet piles, comprising the steps of performing the steps one or more times. 2. The method of coating a steel sheet pile according to claim 1, wherein the 2° powder polyolefin is composed of a polyolefin composition that has sufficient adhesion to the surface of the steel sheet pile. 3. The method for coating steel sheet piles according to claim 1, wherein the surface of the steel sheet piles to be coated with anti-corrosion coating is coated with a single layer of adhesive primer.