JPS6131231A - Manufacture of heavy corrosion resisting coated steel sheet pile - Google Patents

Abstract

PURPOSE:To contrive of show corrosion resisting effect by the corrosion resisting coat made in manufacturing process even at the splash zone of the ocean and the zone of ebb and flow of the tide by molding polyolefin corrosion resisting coat on at least one surface of a steel sheet pile, while pressure-welding resin sheet onto the steel sheet pile. CONSTITUTION:The steel sheet pipe 1 avancing in longitudinal direction undergoes rust removing operation and under ground treatment at a preliminarily treating zone 3, and is preheted at the temperature equal to the crystallizing temperature of denatured polyolefin family adhesive resin or higher and equal to 250 deg.C or lower at the preheating zone 4 o the steel sheet pile. Denatured polyolefin family adhesive resin and polyolefin resin are supplied to two extruders 5 and are molten at a melting zone. Next, said resins are extruded from T type die 6 on the steel sheet pile like a sheet, and the molten molded sheet 7 of each resin is obtained. When two sheets are placed on the steel sheet pile, the molded sheet of adhesive resin is first caused to be in contact with the sheet pile, and to become an inner layer. The surface of coated side is pressed by a press welding roller 8. After the molten molding sheet 7 has been pressure welded to the steel sheet pile, it is cooled. Thus, as at least one surface is corrosion resisting-coated with the thick film of olefin resin in manufacturing process, even at the splash zone in ocean and the ebb and flow zone of the tide, the corrosion resistance may be kept.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for producing heavy corrosion-resistant coated steel sheet piles, and particularly to heavy-duty corrosion-resistant coated steel sheet piles having a corrosion protection layer made of a polyolefin resin formed via a modified polyolefin adhesive resin. This invention relates to a method for manufacturing sheet piles.

(Prior Art) Steel sheet piles are deformed steel materials that are mainly used in civil engineering works such as ports, buildings, sea walls, and earth retaining.

In recent years, countermeasures against corrosion of steel materials such as steel pipe piles and steel sheet piles used for seawalls and port facilities have become a major issue. In other words, steel materials used in the marine environment undergo significant corrosion due to a combination of factors such as tidal fluctuations and seawater spray, as well as direct sunlight and a sufficient supply of oxygen, resulting in use far below their expected useful life. Over the years, the number of cases in which repairs or revisions are required has been increasing.

Conventionally, countermeasures against corrosion of steel sheet piles include increasing the thickness of the steel sheet pile in anticipation of corrosion, electrolytic protection, and the like. Furthermore, even when anti-corrosion coatings are used, for example, on-site coatings such as zinc-rich primer and cool epoxy are simply applied to the steel sheet piles6. However, the conventional methods described above are not reliable. However, this method cannot be said to be fully satisfactory in terms of economic efficiency. For example, if we try to solve the problem of corrosion in offshore structures that require a long service life by using corrosive strips, the required thickness of the steel plate becomes extremely large, which is not only economically disadvantageous but also difficult to handle. Although cathodic protection is very effective underwater, it does not show corrosion protection above the splash zone. Even with the method of using the most reliable anti-corrosion coating, it is difficult to obtain a coating that exhibits a complete anti-corrosion effect in the splash zone and tidal zone of steel sheet piles, where corrosion is most severe, using conventional on-site anti-corrosion coatings. Furthermore, since the anti-corrosion coating applied on-site is a thin film of 111 m or less, it has been impossible to achieve corrosion protection on steel sheet piles for many years.

(Problems to be Solved by the Invention) Therefore, the maintenance method is such that the anti-corrosion coating is applied at the manufacturing stage of steel sheet piles, and the coating is of a thick film type that exhibits sufficient anti-corrosion effects even in the spray zone and tidal zone of the ocean. It is desired to produce free heavy corrosion-resistant coated steel sheet piles.

(Means for Solving the Problems) The present inventors focused on polyolefin resins such as bolyethylene and polypropylene, which have excellent chemical stability, as heavy-duty anti-corrosion coating materials for steel sheet piles, and applied them to steel sheet piles. As a result of research into a continuous coating method that is simple and economical, the present invention was achieved.

Here, the present invention provides a method for manufacturing a heavily anti-corrosion coated steel sheet pile in which a corrosion-resistant layer made of a polyolefin resin is formed on a steel sheet pile via a modified polyolefin-based adhesive resin, in which the steel sheet pile is conveyed in the longitudinal direction. The adhesive resin and polyolefin resin are preheated to a temperature higher than the crystallization temperature of the adhesive resin and lower than 250° C., and the adhesive resin and polyolefin resin are supplied to a sheet melt extrusion device installed near the preheated steel sheet pile. The sheet is extruded from a T-shaped die arranged so that the molded sheet of adhesive resin comes into contact with the steel sheet pile first, is placed on the steel sheet pile, and immediately the side of the steel sheet pile on which the sheet is placed is extruded. 1 arranged so as to be in contact with substantially the entire surface of
This is a method for producing a heavy anti-corrosion coated steel sheet pile, characterized in that a polyolefin anti-corrosion coating is formed on at least one side of the steel sheet pile by pressing the sheet onto the steel sheet pile using two or more rollers.

In this specification, "ll1I sheet pile" includes U-shaped, Z-shaped, and straight-type steel sheet piles. Below, for convenience,
The manufacturing of shaped steel sheet piles will be described, but it is clear that the same process can be performed for Z-shaped and straight-shaped steel sheet piles in the same manner as for U-shaped steel sheet piles.

The manufacturing method of the present invention will be explained with reference to the accompanying drawings. Fig. 1 is a schematic diagram showing the coating method for the dorsal side (convex side) in the production of U-type heavy anti-corrosion coated steel sheet pile according to the present invention, and Fig. 2 is a similar diagram for the ventral side (concave side). This is a schematic diagram of the first equation. 3 and 4 are schematic cross-sectional views of the vicinity of the pressure roller in FIGS. 1 and 2, respectively, showing the arrangement of the pressure roller.

The steel sheet pile 1 is conveyed in the length direction by a plurality of conveyance rollers 2 provided at appropriate intervals. The conveying roller is placed on the ventral side when covering the dorsal side (FIG. 1) and on the dorsal side when covering the ventral side (FIG. 2) so as not to interfere with the covering operation. The advancing steel sheet pile 1 is first subjected to appropriate rust removal or surface treatment such as shot blasting in the pretreatment zone 3, and its surface is cleaned. Next, the steel sheet pile 1 enters the steel sheet pile heating zone 4 and is preheated to a temperature higher than the crystallization temperature of the modified polyolefin adhesive resin used here. The steel sheet piles that have left the preheating zone are coated with polyolefin anti-corrosion coating by the method described below. A modified polyolefin adhesive resin and a polyolefin resin are supplied to two extruder v&5s installed near the steel sheet pile near the exit of the preheating zone, and these resins are melted in the melting section of the extruder. The molten resin is then extruded into a sheet from a T-shaped die 6 attached to each extruder toward a steel sheet pile to form a melt-molded sheet 7 of each resin. (However, in the drawing, only one extruder, T-shaped die, and melt-formed sheet are shown for simplicity.) The arrangement of the two extruders and their T-shaped dies at this time. When the two molded sheets are placed on the steel sheet pile, the adhesive resin molded sheet contacts the steel sheet pile first and becomes the inner layer. That is,
With respect to the conveyance direction, the extruder for the adhesive resin and the T-shaped die are placed on the upstream side, and the extruder and the T-shaped die for the polyolefin resin for the anti-corrosion layer are placed on the upstream side.
Place the mold die on the downstream side. As a result, when both of these sheets are placed on the preheated steel sheet pile being transported, the adhesive resin sheet is placed on the steel sheet pile first, and the sheet of the polyolefin anti-corrosion layer is placed on top of this adhesive resin sheet. The extrusion speed of each resin is set to be substantially the same as the conveyance speed of the steel sheet pile, and the width of each molded sheet (i.e., the slit width of the T-shaped die) is set to the width necessary to cover one side of the steel sheet pile. Each T-shaped die is arranged in a direction perpendicular to the length direction of the steel sheet pile so that the length direction of the steel sheet pile and each formed sheet match.

Instead of using two T-shaped dies, one T-shaped die with two slits can be connected to both extruders for use in the process. In that case, the adhesive resin is extruded from the slit on the side closer to the steel sheet pile, and the polyolefin anticorrosion resin is extruded from the slit on the side farther from the steel sheet pile, to obtain a two-layer laminate sheet.

This laminated sheet is then turned into steel sheet piles! ! When you set
The adhesive resin comes into contact with the steel sheet pile first, and the polyolefin barrier resin comes on top of the adhesive resin.

When the two single-layer sheets or one double-layer laminate sheet obtained by extrusion are placed on the steel sheet pile 1 and come into contact with the steel sheet pile, the sensible heat of the preheated steel sheet pile and the immediately after melt-forming are released. The heat of the resin rapidly melts the adhesive resin, allowing it to function as an adhesive. After that, steel sheet pile 9
The surface covered with the sheet is pressed by a pressure roller 8, and the melt-formed sheet 7 is pressure-bonded to the steel sheet pile 1. This crimping process is performed when covering the back side of a U-shaped steel sheet pile.
As shown in FIG. 3, this is carried out using three pressure rollers 8 arranged on the back side (outside) of the steel sheet pile 1.

Conversely, when covering the ventral side of the steel sheet pile 1, as shown in FIG.
Shift them back and forth as appropriate to prevent them from colliding with each other. The size and arrangement of each roller are such that they can press substantially the entire surface of the steel sheet pile on the side to be crimped.

In order to resist the pressure from the pressure roller on the upper surface of the steel sheet pile, a conveyor roll may be arranged below the pressure roller as shown in FIGS. 1 and 2. In the case of Z-type or straight sheet piles, the dimensions and arrangement of the pressure rollers are similarly designed to contact substantially the entire surface of one side of the steel sheet piles. After crimping, the steel sheet pile coated with the anti-corrosion layer is cooled in the cooling zone 9, and the heavily anti-corrosion coated Wi steel sheet pile according to the present invention is completed. Steel sheet piles are often used for earthworks such as seawall construction, and in that case, only one side is in contact with seawater and the other side is in contact with the soil, so the anti-corrosion coating according to the present invention can be applied to only one side of the steel sheet piles. However, in the case of coating both sides, the coating equipment becomes complicated, but it is preferable to apply the anticorrosion coating according to the present invention to the dorsal side and the ventral side at the same time.

Since the manufacturing process diagrams in the accompanying drawings are merely illustrative, those skilled in the art will be able to easily modify the design and modify the apparatus for double-sided coating.

Next, the materials used and manufacturing conditions will be explained in more detail.

As mentioned above, the coating of the present invention is comprised of a polyolefin resin and a modified polyolefin adhesive resin. The anticorrosive layer of polyolefin resin may be made of commonly used low density polyethylene, high density polyethylene, polypropylene, etc. The thickness of this polyolefin resin is 0.3 to 3.5 mm,
- Preferably, it is within the range of 0.5 to 3.0. If this thickness is too thin, the desired anticorrosion effect may not be obtained, and there is a risk that scratches may be formed that penetrate the coating due to impact during and after application. On the other hand, if it is too thick, the adhesion of the coating will decrease. The modified polyolefin adhesive resin is preferably a polyolefin resin of the same type as that used for the anticorrosion layer, modified with a polar compound such as acrylic acid or maleic anhydride to impart adhesive properties.

The polyolefin resin used for the anticorrosion layer and the polyolefin resin used as the adhesive resin do not necessarily have to be the same polyolefin, but it is preferable to use the same type of polyolefin because the two resins will fit better. The thickness of this adhesive resin layer is 0.1 to 0.3, because if it is too thin, it will not provide sufficient adhesion, and if it is too thick, the adhesion of the anticorrosion layer will deteriorate.
It is desirable that it be within the range of am. The total thickness of the coating including the adhesive layer is 0.5 to 3.5 mm, preferably 1.0 to 2.5 mm.
There will be 5 cranes.

Melt extrusion of the sheet is carried out by extruding each resin melted with an extruder using a T-shaped die with slit gaps so as to form a sheet of the desired thickness as described above, according to a conventional method. . When each resin is formed into a single layer sheet and coated sequentially (hereinafter referred to as single layer extrusion), and when both resins are formed into a 2ii laminate and coated (hereinafter referred to as 2
The melt extrusion operation itself is a well-known technique to those skilled in the art, so further explanation thereof will be omitted.

In any case, as described above, the extruder and T-shaped die are arranged so that the adhesive resin layer is placed on the steel sheet pile first, and the polyolefin anticorrosion layer is placed on top of it.

Preheating of the steel sheet pile can be carried out by a conventional method such as a hot air oven, an infrared heating furnace, or induction heating. By preheating the steel sheet pile, when the adhesive resin layer and further the anti-corrosion layer are placed on top of it, the adhesive resin does not cool down and solidify rapidly, allowing the steel sheet pile to adhere to the resin sheet of the anti-corrosion layer.

If this preheating temperature is too low, the adhesive resin will not be sufficiently melted and will rapidly solidify during bonding, resulting in no or incomplete bonding.

In the method of the present invention, since the resin sheet is at a fairly high temperature immediately after extrusion, it is not necessary to preheat the steel sheet pile to a high temperature above the melting point of the adhesive resin, and the preheating temperature should be above the crystallization temperature of the adhesive resin used. Good to have. On the other hand, if the preheating temperature is too high, it is not only uneconomical, but also causes decomposition or thermal deterioration of the adhesive resin when the steel sheet pile is brought into contact with the resin sheet, which may result in incomplete adhesion. Polyolefins generally tend to decompose when the temperature exceeds about 250°C, so the preheating temperature of the steel sheet pile is set to 250°C or less.

Therefore, the range of preheating temperature for steel sheet piles is 95-250°C for low-density polyethylene, preferably 100-120°C.
0°C, 110 to 250°C for high density polyethylene, preferably 110 to 130°C, and 12 for polypropylene.
The temperature is 0 to 250°C, preferably 130 to 150°C. This preheating does not need to uniformly heat the entire thickness of the steel sheet pile to a desired temperature; it is sufficient that the surface temperature reaches this temperature.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

U-shaped steel sheet piles (effective width 40ON, height 100ON, thickness 10.5ON) were pretreated by shot blasting to give them a clean surface using equipment arranged as shown in the attached drawings. rear,
It was preheated using a hot air stove. On the other hand, each resin sheet for the adhesive layer and the anti-corrosion layer is melt-formed by single-layer extrusion or two-layer extrusion, and then stacked on the steel sheet pile with the adhesive resin layer on the inside and pressed with a roller to form the heavy-duty anti-corrosion steel sheet pile. was manufactured. The conveyance speed of the steel sheet pile and the extrusion speed of the resin sheet are both 3m/
It was min. Table 1 shows the type and thickness of the anticorrosive layer, the type and thickness of the adhesive layer, the extrusion method and extrusion temperature of the resin layer, and the preheating temperature of the steel sheet pile. For comparison, as shown in Table 1, an experiment was also conducted in which the preheating temperature of the steel sheet pile was outside the range of the present invention. The abbreviations in the resin column of Table 1 indicate the following resins.

LDPE: Low density polyethylene (Sumitomo Chemical, Sumikasen G109B') 1 (DPE F high density polyethylene (Showa Denko layer, Shorex 56002) PP: Polypropylene (Mitsubishi Yuka layer, Noblen BC8)
) PEAd: Adhesive polyethylene (Mitsui Petrochemicals, Atmer NEO50) (crystallization temperature 110°C) PPAd
: Adhesive polypropylene (Idemitsu Petrochemical Department, Polytac M-300) (crystallization temperature 120°C) The obtained heavy corrosion-resistant steel sheet piles were evaluated for adhesion, and the results are also shown in Table 1. The adhesion was evaluated by measuring the peeling force in a 180° peel test (Ions width, peeling speed 10 m/min) at 23°C, and the results were as follows: ○: Peeling force was greater than 5 kg/cm, △: 〃 5-3 kg/cm.

X: , /7 Indicated as less than 3 kg/c-.

From the results in Table 1, it can be seen that in Comparative Examples 1.3 and 4, where the preheating temperature of the steel sheet pile was lower than the crystallization temperature of the adhesive resin, the adhesion was extremely high regardless of the type of resin and the extrusion method. bad. This is thought to be because the adhesive resin rapidly solidified during adhesion between the adhesive resin and the steel sheet pile, and sufficient adhesion could not be obtained. Furthermore, in Comparative Example 2 in which the steel sheet piles were preheated at a high temperature, the adhesion was still reduced due to deterioration of the adhesive resin. On the contrary, in all of the examples in which the preheating temperature was within the range defined by the present invention, good adhesion was obtained.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, a heavy corrosion-resistant coated steel sheet pile that does not require maintenance and has a thick anti-corrosion coating of polyolefin resin that has excellent adhesion to steel sheet piles can be easily manufactured. It can be manufactured continuously and economically using a process that

[Brief explanation of drawings]

1 and 2 are schematic diagrams showing the manufacturing process when the dorsal and ventral surfaces of U-shaped steel sheet piles are coated with anti-corrosion coating according to the present invention, and ゛Figs. 3 and 4
The figures are Fig. 1 and 1 Steel Sheet Pile, respectively.
2 @Feed roller 3 Pre-treatment zone 4vI4 sheet pile heating zone 5 Extruder 6 T-shaped die 7
Melt-formed sheet 8 Pressure roller 9 Cooling zone Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Do Hirose - (1 other person) No. 41
Figure 2 Figure 1 Rarely 1L 2. Measurement Liz-ra 3 licking paddle j
゛-n 4-J@L? Souichi Zone 5 Ougi 7 1
6.壬1 Mutan name Su 7 No. 7 - ＾ A second lard 8; Uratsuta de - La 9 Kakugi zone Figure 3

Claims (1)

[Claims] In a method for producing a heavy corrosion-resistant coated steel sheet pile in which a corrosion-resistant layer made of a polyolefin resin is formed on a steel sheet pile via a modified polyolefin-based adhesive resin, the steel sheet pile is conveyed in the longitudinal direction while being transported at a temperature at which the adhesive resin crystallizes. As described above, the adhesive resin and polyolefin resin are preheated to a temperature of 250°C or less, and the adhesive resin and polyolefin resin are supplied to a sheet melt extrusion device installed near the preheated steel sheet pile, and each sheet of these resins is molded into an adhesive resin. The sheet is extruded from a T-shaped die arranged so that the sheet comes into contact with the steel sheet pile first, is placed on the steel sheet pile, and is immediately brought into contact with substantially the entire surface of the side of the steel sheet pile on which the sheet is placed. A method for manufacturing a heavily anti-corrosion coated steel sheet pile, comprising forming a polyolefin anti-corrosion coating on at least one side of the steel sheet pile by pressing the sheet onto the steel sheet pile using one or more rollers arranged to do so.