JP3135933B2 - Heavy corrosion-resistant steel sheet pile and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel sheet pile for use in harbors, rivers, etc., and more particularly to a heavy-duty corrosion-resistant steel sheet pile having improved adhesion and corrosion resistance at its ends.

[0002]

2. Description of the Related Art Steel sheet piles are connected by joints to form steel sheet pile walls, and are used as temporary deadlines and revetment walls in civil engineering works for harbors, rivers, and the like. Corrosion is a major problem for steel sheet piles when used in water environments that are in contact with sea or river water. Until now, measures such as applying anticorrosive paint such as inorganic zinc paint or tar epoxy resin paint have been taken depending on the degree of the environment. However, in recent years, a so-called heavy-corrosion-coated steel sheet pile in which a thick film of a resin such as polyurethane or polyethylene is coated on the sheet pile surface has been developed, and its production method has been disclosed in Japanese Patent Laid-Open No. 59-224717. And Japanese Patent Application Laid-Open No. 62-5837.

As the resin to be coated, as exemplified in Japanese Patent Application Laid-Open No. 62-5837, the use of polyethylene is increasing because of its chemical stability and relatively low price. In particular, in a method of pressing and bonding a resin sheet to the surface of a steel sheet pile as in JP-A-59-224717, it is necessary to make the polyethylene sheet conform to the complicated shape of the steel sheet pile, so that the so-called highly flexible so-called Low density polyethylene is often used.

[0004]

By the way, low-density polyethylene is more concerned with water and oxygen permeation barrier properties, which affect long-term corrosion resistance, and damage to a coating layer during casting, as compared with high-density polyethylene. It is not preferable as a material for heavy-duty corrosion-resistant steel sheet piles because of its poor impact resistance.However, unlike the case of coating over the entire circumference such as a steel pipe, the steel sheet pile is coated at both ends corresponding to the joint side. The cut end is exposed, stress tends to remain in this portion due to the difference in linear expansion coefficient between the steel material and polyethylene, and the adhesion at both ends is weaker than at the center. Therefore, unless low-density polyethylene, which is highly flexible and easily deformed, is not used, there has been a problem that poor adhesion, cracks, cut edges and the like occur at joints and corners having a small curvature.

It is an object of the present invention to realize a polyethylene coating excellent in corrosion resistance and free from such defects.

[0006]

According to the present invention, there is provided an adhesive polyethylene having a melt index of 0.2 to 1.5 g / 10 min and an acid modification amount of 0.05% or more, a linear low density polyethylene or a high density polyethylene.
A laminated sheet obtained by laminating an anticorrosive polyethylene having a modulus of elasticity of 2000 to 10,000 kg / cm ² which is polyethylene at 40 to 70 ° C.
Preheated to a temperature of at least the melting point of the adhesive polyethylene, and attached to the surface of the steel sheet pile to cover it.

[0007] Adhesive polyethylene has a problem that if the melt index is less than 0.2 g / 10 min, sufficient adhesive strength cannot be obtained, and if it exceeds 1.5 g / 10 min, the fluidity is too high and shrinkage occurs after bonding. is there. The melt index is also referred to as a melt flow rate, and expresses the fluidity of the resin using the amount of outflow from the orifice for 10 minutes under constant conditions, and is hereinafter referred to as MFR. If the amount of modification of the adhesive polyethylene is less than the above amount, sufficient adhesive strength cannot be obtained.

As an anticorrosive polyethylene, an elastic modulus of 2000 to
The reason why the polyethylene resin of 10,000 kg / cm ² is used is that if it is less than this, the corrosion resistance at around 60 ° C. is remarkably deteriorated, and if it is more than this range, it is difficult to process the corners and joints. In order to maintain a long-term anticorrosion property, it is preferable to add an antioxidant such as a naphthylamine derivative or a substituted phenol or an ultraviolet absorber such as carbon black to the anticorrosion polyethylene.

Further, if the preheating temperature of the laminated polyethylene is below the above range, the steel sheet pile side must be heated extra for adhesion, and if the steel sheet pile surface is coated with a primer or the like, these deteriorations may occur. I am concerned. Conversely, if the preheating temperature is higher than the above range, the polyethylene will be too soft, and the resin will flow due to the application pressure at the time of coating, and a locally thin portion will be formed or ears will be cut off.

The thickness of each of the anticorrosive polyethylene layer and the adhesive polyethylene layer is 0.1 to 3.0 mm, preferably
0.2 to 2.0 mm, and the ratio of the two is preferably in the range of 10: 1 to 1: 1. Various methods are conceivable for producing such a laminated polyethylene sheet. For example, anticorrosive polyethylene is continuously extruded by a known T-die, and an adhesive polyethylene is extruded thereon from another T-die and laminated. Just do it.

The heating temperature of the sheet pile is from about 100 ° C., which is the melting point of the adhesive polyethylene, to about 250 ° C., preferably from about 120 ° C., which is 20 ° C. higher than the melting point of the adhesive polyethylene, to 200 ° C. Chromic acid treatment in advance,
Phosphoric acid treatment, primer application, etc. may be performed.
FIG. 1 is an explanatory view in which a laminated sheet of the present invention is coated on a steel sheet pile. As shown in FIG. 1A, an adhesive polyethylene 4 and an anticorrosive polyethylene 5 are laminated on a steel sheet pile 1 with the adhesive polyethylene 4 facing the sheet pile. The laminated sheet 3 is sequentially pressed from the center of the steel sheet pile toward the joints on both sides to obtain a coated steel sheet pile of (b). In this figure, the concave portion of the sheet pile is covered, but the same applies to the case where the convex portion is covered.

[0012]

According to the present invention, the presence of the adhesive polyethylene layer between the anticorrosive polyethylene and the steel sheet pile allows
Good adhesion is obtained, the line as a corrosion resistant polyethylene
Since low-density polyethylene or high- density polyethylene can be used, excellent anticorrosion performance can be exhibited over a long period of time.

Further, by defining the preheating temperature of the laminated polyethylene and the elastic modulus of the anticorrosion polyethylene of the upper layer, a sound covering layer without cuts or reduced thickness at joints and corners can be formed.

[0014]

EXAMPLES Examples of the present invention and comparative examples will be described below. Example 1 As a corrosion-resistant polyethylene, a linear low-density polyethylene having an elastic modulus of 4300 kg / cm ² was melt-extruded into a sheet having a thickness of 1.9 mm. mm were laminated to form a laminated sheet.

After shot blasting the concave surface of the U-shaped steel sheet pile, chromate treatment 1 μm, epoxy primer 50
μm, heated to 180 ° C with a burner, and pressed the laminated sheet preheated to 50 ° C with a roll and pressed sequentially from the center of the steel sheet pile toward the joints on both sides to produce a polyethylene-coated heavy duty steel sheet pile. did. Example 2 As anticorrosive polyethylene, a high-density polyethylene having an elastic modulus of 8000 kg / cm ² was melt-extruded into a sheet having a thickness of 1.9 mm, and an MFR of 0.3 g / 10 min and an adhesive polyethylene thickness of 0.4 mm having an acid modification amount of 0.15% were added. The laminated sheet was laminated to produce a polyethylene-coated heavy duty corrosion-resistant steel sheet pile in the same manner as in Example 1.

Comparative Example 1 A high-density polyethylene having a modulus of elasticity of 12000 kg / cm ² was melt-extruded into a sheet having a thickness of 1.9 mm as an anticorrosive polyethylene. 0.4 mm was laminated to form a laminated sheet, and a polyethylene-coated heavy duty corrosion-resistant steel sheet pile was produced in the same manner as in Example 1.

Comparative Example 2 A low-density polyethylene having an elastic modulus of 1000 kg / cm ² was melt-extruded into a sheet having a thickness of 1.9 mm as an anticorrosive polyethylene, and an adhesive polyethylene having an MFR of 0.9 g / 10 min and an acid modification amount of 0.15% was prepared. 0.4 mm was laminated to form a laminated sheet, and a polyethylene-coated heavy duty corrosion-resistant steel sheet pile was produced in the same manner as in Example 1.

Comparative Example 3 A polyethylene-coated heavy duty steel sheet pile was manufactured in the same manner as in Example 1 except that the preheating temperature of the laminated polyethylene was set at 10 ° C. Comparative Example 4 A polyethylene-coated heavy duty steel sheet pile was manufactured in the same manner as in Example 1 except that the preheating temperature of the laminated polyethylene was 90 ° C.

Table 1 shows the evaluation test results for the above Examples and Comparative Examples.

[0020]

[Table 1]

[0021]

According to the present invention, a heavy-corrosion-coated steel sheet pile having excellent adhesion strength, corrosion resistance and impact resistance can be obtained, and the durability of the steel sheet pile structure is improved, so that maintenance costs such as corrosion protection and repair are improved. Is reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a method for manufacturing a coated steel sheet pile according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel sheet pile 2 Joint part 3 Laminated sheet 4 Adhesive polyethylene 5 Corrosion-proof polyethylene

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takafumi Hashimoto 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. Chome (without address) Kawasaki Steel Corporation Mizushima Works (56) References JP-A-61-5921 (JP, A) JP-A-2-74334 (JP, A) JP-A-60-8058 (JP, A JP-A-63-154330 (JP, A) JP-A-60-230848 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 15/08 103 E02D 5/04-5 / 08

Claims (2)

(57) [Claims] 1. A melt index on a surface of a steel sheet pile.
0.2-1.5g / 10min , adhesive polyethylene with acid modification amount of 0.05% or more and linear low density polyethylene or high density polyethylene
A heavy-duty anticorrosion steel sheet pile characterized by laminating, in this order, anticorrosion polyethylene having an elastic modulus of 2000 to 10,000 kg / cm ² , which is styrene. 2. A melt index of 0.2 to 1.5 g / 10 min ,
Adhesive polyethylene with acid-modified amount of 0.05% or more and linear low density
Elastic modulus which is polyethylene or high density polyethylene
Laminated sheet made by laminating anticorrosive polyethylene of 2000 to 10000 kg / cm ² is preheated to 40 to 70 ° C, and is adhered to the steel sheet pile surface heated above the melting point of adhesive polyethylene to cover it. Manufacturing method of heavy duty steel sheet pile.