JPH1177898A - Manufacturing and device for heavy corrosion-resistant coated steel sheet pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated layer having excellent long-term adhesion in sea water by heating, before adhering, a part corresponding to a curved part of a steel sheet pile of a corrosion-resistant polyolefin sheet. SOLUTION: A heavy corrosion-resistant coated steel sheet pile is composed by forming a modified polyolefin layer 3 on a sheet pile 1, where blasting and formation treatment, and pretreatment of a primer layer 3 are applied, and adhering a sheet composed of a corrosion-resistant polyolefin layer 4 thereon. Before coating the corrosion-resistant polyolefin sheet, hot air is blasted to a part to be heated, that is, a sheet part to be adhered to a curved surface part of the steel sheet pile 1, using a heat source such as an infrared heater or the like. Heating temperature is (mp-60)<=T<=(mp-5), where in mp ( deg.C) is melting point of a resin composing the corrosion-resistant polyolefin sheet, and T ( deg.C) is a maximum temperature of the sheet heated part. If the heating temperature is over (mp-5), the sheet melts before the adhering process. If the temperature is lower than (mp-60), improving effect of long-term adhesion developed by heating is smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a heavy-duty coated steel sheet pile in which a heavy-duty corrosion-resistant coating is formed on the surface of a steel sheet pile by sticking a polyolefin sheet. The present invention relates to a method and an apparatus for manufacturing a heavy-duty anti-corrosion coated steel sheet pile having excellent long-term adhesion with the sheet pile.

[0002]

2. Description of the Related Art Steel sheet piles forming quays of oceans, harbors, rivers, etc. are exposed to a severe corrosive environment. Therefore, a sheet made of polyolefin resin such as polyethylene or polypropylene is adhered to the surface of the sheet piles via an adhesive layer. By doing so, so-called heavy-corrosion-coated steel sheet piles that have been subjected to corrosion protection have been increasingly used.

[0003] This heavy-corrosion coated steel sheet pile is disclosed in Japanese Patent Laid-Open No. 60-8 / 1985.
No. 058, as disclosed in Japanese Patent Application Laid-Open No. 60-27520, etc., formed on a steel sheet pile whose base has been adjusted, by sequentially forming a chemical conversion treatment layer, a primer layer, a modified polyolefin layer, and an anticorrosion polyolefin layer, As a production method, a method is known in which a sheet in which a modified polyolefin layer and an anticorrosion polyolefin layer are integrated is attached to a preheated steel sheet pile to produce the sheet.

Japanese Patent Application Laid-Open No. 60-27520 discloses that
It is also disclosed that the sheet is entirely heated immediately after the roll uncoil.

[0005]

However, the polyolefin-coated steel sheet pile manufactured by sticking the sheet has a large end ratio due to the property of sticking the sheet to one side of the steel material, and other heavy corrosion-resistant steel materials, for example, Compared to a polyethylene-coated steel pipe pile or the like, there is a problem that the possibility of causing a decrease in adhesion due to intrusion of seawater or the like from the end is slightly higher.

In order to increase the long-term reliability of polyolefin-coated steel sheet piles and further improve their service life, it is extremely important to further improve the long-term adhesion of the sheets of polyolefin-coated steel sheet piles, especially in seawater. It has become.

The present invention has been made in order to solve the above-mentioned problems, and relates to a heavy-duty corrosion-resistant coated steel sheet pile having a polyolefin sheet adhered to the surface of the steel sheet pile, and to provide a long-term adhesion of the coating layer in seawater. It is an object of the present invention to provide a heavy-duty anticorrosion-coated steel sheet pile having excellent resistance.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to further improve the long-term adhesiveness of a sheet in a polyolefin-coated steel sheet pile, and as a result, a modified polyolefin layer was formed on a heated steel sheet pile that had been subjected to a base treatment. In the method for producing a heavy-corrosion-resistant coated steel sheet pile coated with a corrosion-resistant polyolefin sheet through, a portion corresponding to the curved surface portion of the steel sheet pile of the corrosion-resistant polyolefin sheet is heated to a predetermined temperature before sticking, so that seawater of the coating layer is formed. The present inventors have found that a heavy-duty anticorrosion-coated steel sheet pile excellent in medium-term long-term adhesion can be obtained, and have completed the present invention.

That is, the present invention relates to a method for manufacturing a heavy-corrosion-resistant coated steel sheet pile, comprising applying a corrosion-resistant polyolefin sheet to a heated steel sheet pile subjected to a base treatment via a modified polyolefin layer. The present invention relates to a method for manufacturing a heavy-duty coated steel sheet pile characterized by heating a portion corresponding to the above before sticking, a method for manufacturing a heavy-duty coated steel sheet pile enabling such a manufacturing method, and an apparatus used therefor It is.

[0010] It is an unexpected effect that the long-term adhesion of the sheet is improved by heating a specific portion of the sheet before sticking as in the present invention. The effect of reducing the residual stress and the effect of suppressing the occurrence of the adhesion failure region at the corner portion are given. That is, when a polyolefin sheet is adhered to a curved surface portion of a heated steel sheet pile, a large residual strain is generated due to the bending of the sheet. Since the force of returning the sheet due to the residual strain acts in the direction of peeling the sheet, there is a possibility that the floating of the sheet immediately after sticking or the peeling of the sheet from a corner portion during use may be promoted.

On the other hand, the higher the temperature of polyethylene, the lower the yield stress and the faster the stress relaxation rate. Therefore, bending at a higher temperature reduces residual stress accompanying bending. When polyethylene is adhered, the temperature rises when it comes into contact with the high-temperature steel sheet pile through the adhesive layer, so the above-mentioned yield stress reduction effect and stress relaxation effect can be expected slightly,
In the present invention, by heating a region corresponding to the corner portion of the sheet in advance, it is expected that the yield stress lowering effect and the stress relaxing effect at the time of bending at the time of bonding are remarkably promoted.

The excellent long-term adhesion of the coated steel sheet pile produced by the method of the present invention is presumed to be due to the above reasons.

In the method of heating the entire sheet as disclosed in Japanese Patent Application Laid-Open No. 60-27520, sufficient heating cannot be performed so as not to cause elongation and deformation of the sheet. The solution had to be insufficient.

[0014]

Embodiments of the present invention will be described below in detail. As shown in FIG. 1, the heavy-corrosion-coated steel sheet pile of the present invention includes a steel sheet pile 1, a primer layer 2, a modified polyolefin layer 3, and a corrosion-resistant polyolefin layer 4.

The steel sheet piles used in the present invention include harbors, rivers,
Used for revetment of landfills, etc.
U-type, Z-type, I-type specified in 5528, and those having a shape conforming thereto can be used. There are no particular restrictions on its dimensions. In the present invention, heavy anticorrosion coating is applied to a portion where anticorrosion needs to be applied. For example, when used for seawall protection in a port, the coating is often applied mainly to the side facing the sea. It goes without saying that heavy corrosion protection can be applied to both sides of the steel sheet pile.

The steel sheet pile used in the present invention is subjected to a known base adjustment such as degreasing, pickling, shot blasting, grit blasting, and sand blasting to remove oil, scale, and the like on the surface of the steel material. It is desirable. The level of the substrate adjustment is preferably, for example, about Sa2 1/2 or more in the Swedish standard (SIS). If the substrate adjustment is insufficient, the long-term anticorrosion of the heavy duty anticorrosion coating is significantly impaired. Furthermore, long-term adhesion can be achieved by performing a chemical conversion treatment such as a known chromate treatment.
It is preferable from the viewpoint of anticorrosion properties.

The primer layer used in the present invention is an epoxy resin-based or urethane resin-based organic resin-based primer having excellent adhesion between the surface of the steel sheet pile whose base material has been adjusted and the modified polyolefin layer. Used.
The primer layer is formed by a known coating method such as air spraying, airless spraying, brush coating, or the like, and if necessary, heated after coating to form a complete cured film. The thickness of the primer layer is about 10 to 200 μm, particularly 20 to 200 μm.
It is preferably about 100 μm. If the thickness is less than 10 μm, the adhesion between the polyolefin sheet and the steel material is reduced.
There is a problem that the polyolefin sheet is peeled off, and if the thickness exceeds 200 μm, the residual stress of the primer layer itself increases, which adversely affects the long-term adhesion of the sheet.

The modified polyolefin used in the present invention is obtained by modifying a polyolefin resin such as polyethylene or polypropylene with an unsaturated carboxylic acid such as maleic acid, acrylic acid or methacrylic acid or an anhydride thereof by a graft reaction or the like. It refers to a resin that has significantly improved adhesion to other substances as compared to a simple substance. Modified polyolefins are known to have various thermal properties depending on the type and amount of the functional group to be grafted, but the Vicat softening point of the modified polyolefin used in the present invention is 50 ° C.
The temperature is preferably 120 ° C. or lower and 120 ° C. or lower. If the softening point is less than 50 ° C., it is not preferable because the temperature rise due to sunshine or the like causes a decrease in the adhesiveness of the sheet in the aerial part of the heavy-duty steel sheet pile. Energy cost increases due to
It is not preferable because long-term adhesion decreases due to an increase in thermal stress accompanying an increase in the bonding temperature. Further, when the temperature exceeds 90 ° C., an increase in the residual stress of the sheet tends to be a problem. Therefore, a more preferable Vicat softening point is 50 to 90 ° C, further preferably 55 to 80 ° C, particularly preferably 55 to 70 ° C.
It is.

In the other physical properties of the modified polyolefin,
Melt index is about 0.2 to 10 g / 10 min, preferably about 0.5 to 5 g / 10 min, and melting point is 60 to 135.
C., and preferably about 60 to 100.degree. This modified polyolefin layer functions as an adhesive layer for the anticorrosion polyolefin layer, and the layer thickness is 0.1
About 1.5 mm, preferably about 0.2 to 1 mm.

The polyolefin resin of the anticorrosion polyolefin layer used in the present invention is a low-density polyethylene,
Known polyolefins such as medium density polyethylene, high density polyethylene, linear low density polyethylene and polypropylene, and known polyolefin copolymers such as ethylene-propylene random or block copolymers.

Particularly preferred are those having a density of 0.940 g.
/ Cm ³ or more, so-called high-density polyethylene. For the purpose of improving environmental stress crack resistance, impact resistance, and toughness, an ethylene copolymer containing a polyolefin-based component such as propylene, butene-1, hexene-1, or the like as a copolymer component can also be used. The upper limit of the density does not matter, but a commercial product is usually 0.1.
About 970 g / cm ³ is the upper limit. Particularly preferred density is about 0.940 to 0.960 g / cm ³ . The melt index is preferably not more than 0.3 g / 10 minutes, and is preferably about 0.1 to 0.3 g / 10 minutes. 0.3g
If the time exceeds / 10 minutes, environmental stress and cracking property are undesirably reduced. The Vicat softening point is 100-130 ° C.
Degree, especially about 110-125 ° C. Preferred softening point difference with the modified polyethylene layer is 10 to 70 ° C.
It is about.

Also, several cross-linking methods such as electron beam cross-linking, silane cross-linking, and chemical cross-linking are known for polyethylene, and these cross-linked polyethylenes are generally used for heavy-duty corrosion-resistant steel sheet piles. It is preferable to use a non-crosslinked polyethylene without using a crosslinked polyethylene. This is because the effect of relaxing the stress after cooling is not hindered. On the other hand, since high-density polyethylene has sufficient mechanical strength, it is not necessary to take a crosslinked structure.

It is preferable to add various additives such as carbon black, coloring pigments and antioxidants to the anticorrosion polyolefin layer in order to improve long-term properties such as weather resistance. The thickness of the anticorrosion polyolefin layer is about 1 to 6 mm, particularly 1 to 4 mm.
The range of about mm is preferable from the viewpoint of long-term adhesion, long-term corrosion resistance, and maintenance of the mechanical strength of the coating layer. By the way, the standard of anti-corrosion polyolefin of heavy corrosion-resistant steel sheet pile is 2.
0 mm or more, and generally the thickness of the anticorrosion polyolefin layer is often 2.0 mm or more.

Next, a method of manufacturing a heavy-corrosion-coated steel sheet pile according to the present invention will be described. The scale is completely removed by blasting, and a chemical conversion treatment such as a chromate treatment is performed. Further, the primer coating is applied by a spray coating method or another method, and cured by standing or heating to form a primer layer.

The steel sheet pile that has been subjected to the blasting, chemical conversion treatment, and primer treatment such as primer coating is heated by a heating device such as a heating furnace. The heating temperature needs to be a temperature necessary for fusing the polyolefin sheet, and therefore, is higher than the melting point of the modified polyolefin layer, preferably 10 to 100 from the melting point.
This is a temperature that is as high as about ℃, and is usually in the range of about 80 to 200 ℃.

The heated steel sheet pile is coated with an anticorrosion polyolefin layer via a modified polyolefin layer. As this coating method, a modified polyolefin layer and an anticorrosive polyolefin layer are integrated to form a molded polyolefin sheet, and the integrated sheet is supplied onto a steel sheet pile so that the modified polyolefin layer side contacts the steel sheet pile. preferable. However, it is not always necessary to integrate them, and only the modified polyolefin layer may be formed in advance on a steel sheet pile that has been subjected to base treatment, and a sheet made of only the anticorrosive polyolefin layer may be adhered thereon. In this case, the modified polyolefin layer may be formed by melt extrusion coating, powder coating, fluid immersion, thermal spraying, sheet sticking, or the like. Also, to heat bond the polyolefin sheet,
The modified polyolefin layer needs to be at least in a molten state.

The most characteristic feature of the present invention is that, before coating the anticorrosion polyolefin sheet, a region corresponding to the curved portion of the steel sheet pile of the sheet is heated. The region corresponding to the curved surface portion is a portion of the sheet to be adhered to a portion where the surface of the steel sheet pile is bent, and preferably, the bending angle of the surface of the steel sheet pile (the angle with respect to the tangential direction of the surface) is 30 degrees or more. And particularly preferably a site corresponding to 60 degrees or more. Specifically, for example, the regions shown in FIGS. 4 and 5 are used. When the sheet is attached to the concave surface of the steel sheet pile, when the sheet is attached to the convex portion of the steel sheet pile shown in FIG. Are the two locations shown in FIG. The area to be heated has a width of 2 to 5c centering on the point corresponding to the vertex of the curved portion of the steel sheet pile.
What is necessary is just to heat mainly the range of the m-th place. In fact, it goes without saying that the heat at the time of heating is also diffused to the surrounding area, and the temperature of the surrounding area is also increased.

Heating is preferably performed immediately before the application in terms of thermal efficiency.

As a heating method, a method of using a heat source such as an infrared heater, a laser, an electric heater or a gas burner to blow hot air to a portion to be heated, and a method of using radiant heat are effective. It is preferable that this heating be performed only in the region corresponding to the curved surface portion from the viewpoint of heating efficiency and energy cost reduction. However, if a sufficient temperature rise can be achieved even by heating the entire sheet, there is no problem.

The heating temperature is: (mp-60) ≦ T ≦ (mp) where the melting point mp (° C.) of the resin constituting the anticorrosive polyolefin sheet and the maximum temperature at the heated portion of the sheet are T (° C.). -5). If the sheet is heated to a temperature higher than (mp-5), there is a risk that the sheet will melt from the stage before the application, and if the sheet is heated to a temperature lower than (mp-60), the effect of improving the long-term adhesion by heating will be reduced. The lower limit of the maximum temperature is more preferably (mp-50) ° C, particularly preferably (mp-40) ° C, and the upper limit is more preferably (mp-10) ° C, particularly preferably (mp-15) ° C. is there.

With respect to heating, it is preferable to heat the sheet while controlling the sheet to an optimum temperature while measuring the temperature of the corner portion by a measuring means such as a temperature sensor.

The sheet heated at the portion corresponding to the curved portion of the steel sheet pile is supplied onto the steel sheet pile. After the supply, the sheet is stuck to the steel sheet pile with a pressing device such as a roll. In this case, it is preferable to sequentially press the steel sheet pile from the central portion to the curved surface portion and then to the peripheral portion in order to prevent air bubbles and the like from being mixed into the sheet and to efficiently attach the sheet.

After completion of the fusion, the sheet pile to which the sheet has been attached is cooled with water or the like, the excess length of the sheet is trimmed, and if necessary, the edges are sealed. Is completed.

The apparatus for producing a heavy corrosion-resistant coated steel sheet pile of the present invention comprises:
It is characterized in that it has a mechanism for heating a portion of the anticorrosion polyolefin sheet corresponding to the curved portion of the steel sheet pile before sticking as described above. The heating mechanism is performed by laser, infrared rays, hot air blowing, flame blowing, etc. using infrared heater, laser, electric heater, gas burner etc. as a heat source as described above. Use of nozzle to increase the accuracy of the heated part, concave reflection The use of a mirror is also preferred.

[0035]

Embodiments of the present invention will be described below.

U-shaped steel sheet pile (effective width 500 mm, height 22
5mm, 24.3mm thick, 6m long) Concave surface is sandblasted to SIS Sa2 1/2, chromate treatment agent is applied and baked on the surface in contact with the sea at the time of use, all chromium adhered 500 mg / m ²
Was formed. After curing the unpainted part, an epoxy-based primer was spray-coated on the surface so as to have a thickness of 40 μm, and was cured by heating.

Thereafter, the steel sheet pile was heated to 140 ° C. in a heating furnace to form a sheet in which a modified polyethylene layer having a thickness of 0.5 mm and a corrosion-resistant polyethylene layer having a thickness of 2.0 mm were integrated with the steel sheet pile in a high temperature state. Was placed and pressed to fuse. The modified polyethylene is a maleic anhydride-modified polyethylene having a Vicat softening point of 70 ° C., a melting point of 80 ° C., and a MI of 3.0.
g / 10 minutes, and the density was 0.90 g / cm ³ . The anticorrosion polyolefin used had a Vicat softening point of 110 ° C. and a melting point of 125 ° C.

At this time, at the stage before the sheet is attached, the portions (four portions, FIG.
Was heated to various temperatures.

FIGS. 2, 3 and 4 show the partial heating apparatus.
The following was used. FIG. 2 is a perspective view of a heavy-corrosion-coated steel sheet pile manufacturing apparatus according to one embodiment of the present invention, and FIG. 3 is a view seen from a side. FIG. 4 is a top view of a heavy-corrosion-coated steel sheet pile manufacturing apparatus according to one embodiment of the present invention. Steel sheet pile 5
Is placed on the transport roll 6 with the concave surface facing upward and proceeds rightward in the drawing. The polyethylene sheet 7 is paid out from a coil 8 which is supported so as to be able to roll upward, and is laid on the upper surface of the steel sheet pile 5. Above the polyethylene sheet 7, four electric heaters 9 are provided in accordance with the heating portions (FIGS. 5 and 6) of the sheet, and heat the portion of the polyethylene sheet 7 fed out as indicated by H in FIG. 2. .

Table 1 shows conditions such as the heating temperature (the ultimate temperature of the heated portion at the highest temperature). The heating temperature was measured by a radiation thermometer, and the measurement was performed while performing feedback control so as to reach a predetermined heating temperature.

A notch was cut into the end of the heavy-duty corrosion-resistant steel sheet pile prepared at the sheet preheating temperature shown in Table 1, and the sheet pile was driven into the quay with artificial peeling of about 1 cm.

Further, the coating material of the steel sheet pile is partially peeled off,
From the state of the peeled surface, the adhesion state of the curved portion of the steel sheet pile was observed.

Further, the coated steel sheet pile is placed 30 cm in the width direction.
It was cut so as to be about the width, immersed in a 3% aqueous sodium chloride solution at 50 ° C., and the state of peeling of the coating layer was observed over time.

Table 1 shows the conditions for preparing the tested steel sheet piles and the results of the tests and observations.

[0045]

[Table 1]

In Comparative Example 1, the sheet was partially melted, was significantly deformed, and could not be pasted.

As described above, the heavy-corrosion-coated steel sheet pile produced by the method of the present invention exhibited extremely excellent adhesion even after long-term exposure in the sea. In addition, the state of sticking of the curved surface portion was good, and excellent adhesion was shown in an accelerated test such as a salt water immersion test.

[0048]

As described above, the heavy-corrosion-coated steel sheet pile of the present invention exhibits extremely excellent long-term adhesion in an actual exposure test and an acceleration test. Therefore, it is possible to prevent loss of repair cost and the like due to peeling of the coating of the coated steel sheet pile,
There are significant economic effects.

Further, since the heating of the sheet has a sufficient effect even if it is very local, it is a method which is very excellent in energy cost as compared with the case where the sheet is entirely heated.

According to the apparatus of the present invention, a heavy duty anticorrosion coated steel sheet pile having excellent long-term adhesion as described above can be efficiently produced.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a heavy-corrosion-coated steel sheet pile of the present invention.

FIG. 2 is a perspective view schematically showing the configuration of an embodiment of the manufacturing apparatus of the present invention.

FIG. 3 is a side view schematically showing the configuration of an embodiment of the manufacturing apparatus of the present invention.

FIG. 4 is a top view schematically showing the configuration of an embodiment of the manufacturing apparatus of the present invention.

FIG. 5 is a view showing a heated portion when a polyolefin sheet is attached to a steel sheet pile.

FIG. 6 is a view showing a heated portion when a polyolefin sheet is attached to a steel sheet pile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel sheet pile 2 Primer layer 3 Modified polyolefin layer 4 Anticorrosion polyolefin layer 5 Steel sheet pile 6 Conveyance roll 7 Polyolefin sheet 8 Polyolefin sheet coil 9 Electric heater H Heating part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Shinohara 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Yoshiro Saito 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun Inside the Honko Tube Co., Ltd. (72) Inventor Mitsugu Fuzen 1-1-2 Marunouchi, Chiyoda-ku, Tokyo

Claims (4)

[Claims] 1. A method for manufacturing a heavy-duty corrosion-resistant coated steel sheet pile, comprising applying a corrosion-resistant polyolefin sheet to a heated steel sheet pile subjected to a base treatment via a modified polyolefin layer, the method corresponding to a curved surface portion of the steel sheet pile of the corrosion-resistant polyolefin sheet. A method for producing a heavy duty anti-corrosion coated steel sheet pile, characterized by heating the part before sticking. 2. The method according to claim 1, wherein the portion corresponding to the curved surface of the steel sheet pile of the anticorrosion polyolefin sheet is heated before being adhered until the following relational expression is satisfied. Method. (Mp-60) ≦ T ≦ (mp-5) mp: Melting point of anticorrosion polyolefin sheet T: Maximum temperature of anticorrosion polyolefin sheet 3. The anticorrosion polyolefin sheet has a density of 0.9.
^{3. The} method according to claim 1, wherein the non-crosslinked polyethylene is 40 g / cm ³ or more. 4. An apparatus for manufacturing a heavy-duty anticorrosion-coated steel sheet pile that applies a corrosion-resistant polyolefin sheet via a modified polyolefin layer to a heated steel sheet pile subjected to a base treatment, wherein the apparatus corresponds to at least a curved surface portion of the steel sheet pile of the corrosion-resistant polyolefin sheet. An apparatus for manufacturing a heavy-duty coated steel sheet pile, characterized by having a mechanism for heating the part before attaching.