JPH039253B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a plastic-coated steel sheet pile used in civil engineering and construction, which has high corrosion resistance, durability, and economic efficiency. [Prior Art] Steel sheet piles are widely used for bank protection in rivers, coasts, etc., or for preventing mud and sand from flowing in and out at construction sites. The environment in which this steel sheet pile is used is always water, oxygen,
Steel sheet piles, which come into contact with corrosive factors such as ultraviolet rays and are expected to be used for a long period of time, are required to continue exhibiting excellent anti-corrosion performance throughout the period of use. In response to such demands, tar
In most cases, it was coated with thermosetting plastic such as epoxy resin or FRP. [Problems to be solved by the invention] By the way, in the former method of coating thermosetting resin, there is still room for improvement in the mechanical strength of the coating and long-term corrosion resistance.
In the case of covering with FRP, there were problems in workability and economic efficiency. In addition, steel sheet piles have been tested that are simply made of thermoplastic sheets pasted together with a suitable adhesive. Although the properties of this coating itself are sufficient, since the edges of the coating are in direct contact with corrosive factors, after long-term use, the edges will begin to peel. However, this cannot be said to be a satisfactory corrosion prevention method, and there has been a desire to develop a corrosion-resistant coated steel sheet pile that can withstand use for a longer period of time. [Means for Solving the Problems] Under these circumstances, the present invention was developed as a result of various studies on the corrosion protection of steel sheet piles. A thermoplastic plastic coating layer is formed thereon via an adhesive thermoplastic plastic coating layer, and a low-rigidity and high-elasticity elastomer coating section is provided so as to span the ends of each of these coating layers and the steel sheet pile surface, Moreover, a plastic-coated steel sheet pile has been achieved, characterized in that the contact surfaces of the ends of each of the coating layers with the low-rigidity, high-modulus elastomer coating are treated to prevent peeling. [Operation] Hereinafter, the configuration and effects of the present invention will be specifically explained based on the drawings. FIGS. 1 and 2 are cross-sectional views of typical examples of plastic-coated steel sheet piles formed according to the present invention, in which a thermosetting plastic coating layer 2 is applied to the surface of the steel sheet pile 1. , an adhesive thermoplastic plastic layer 3, a thermoplastic coating layer 4, and a low-rigidity/high-elasticity elastomer coating layer 5.
was formed. The thermosetting plastic layer 2 is provided on the surface of the steel sheet pile 1, and is intended to improve the affinity between the steel sheet pile 1 and the adhesive thermoplastic plastic layer 3, and may be an extremely thin layer. This thermosetting plastic layer 2 is formed for the purpose of improving the compatibility with the adhesive thermoplastic plastic layer 3 coated thereon, and as a result, maintaining the anticorrosion effect over a long period of time. It is something that exists. Specifically, uncured or semi-cured thermosetting plastics in liquid or powder form are applied and cured and formed into a film by heating.For this purpose, aliphatic amines, aromatic Epoxy resins with a molecular weight of about 300 to 4000 are cured with curing agents containing amines, acid anhydrides, polyamines, polyamides, imidazole, etc., and polyols or polyols modified with epoxy are cured with isocyanates. can do. On top of this thermosetting plastic covering layer 2 there is arranged a plastic covering layer 3 which is adhesive and thermoplastic. This adhesive thermoplastic plastic layer 3 is located between the thermosetting plastic coating layer 2 and the thermoplastic plastic coating layer 4 and serves to tightly bond them together. The thermoplastic plastic coating layer 4 specifically exhibits the anticorrosion effect intended by the present invention,
Its materials include high to low density polyethylene, polypropylene, ethylene, propylene copolymer,
It is formed from a composition whose main components are polybutene-1, polyamide, thermoplastic polyester, ABS resin, polyvinyl chloride, polymethylpentene-1, etc. In order to improve the mechanical strength, weather resistance, and heat resistance of the thermoplastic coating layer 4, which is an anticorrosive layer,
Inorganic materials such as silica, alumina, talc, mica, carbon black, glass particles, and glass fibers may be added, and in addition, antioxidants, ultraviolet absorbers, pigments for coloring, etc. may be added as necessary. may be added. The material used for the coating layer 3 is one obtained by modifying the coating layer 4 with a carboxylic acid or its anhydride. The present invention is characterized by a method for treating the edges of the coating having such a structure. More specifically, at the end of each pre-formed plastic layer, a specific surface treatment as shown below is applied to a predetermined width from the end of the outermost layer, and then the material has low rigidity and high elasticity. The elastomer 5 is used to cover the ends of the plastic layer and the steel sheet pile. The low-rigidity/high-elasticity elastomer coating layer 5 is formed for the purpose of maintaining the adhesion of the thermoplastic plastic coating layer 4 to the steel sheet pile 1 for a long period of time, and is in a state where it overlaps all end surfaces of the thermoplastic plastic coating layer 4. It is made to form continuously. The function of this part is to prevent water from leaking during use as a steel sheet pile.
It resists physical and chemical effects that would cause the end face of the thermoplastic coating layer 4 to peel off from the steel surface, such as contact with seawater, steam, etc., and temperature differences during the day or throughout the year. The materials include synthetic resin-based oil-based caulking materials, elastomer compositions such as butyl rubber, isoprene rubber, and chloroprene rubber, oxime-free and acetone-free silicone rubber compositions, elastic polyurethane compositions, and polysulfide-based elastomer compositions. Materials that have fluidity in an uncured state and exhibit low rigidity and high elasticity after curing can be mentioned. Due to the presence of this low-rigidity, high-elasticity elastomer coating layer 5, there is no direct contact between the interface between the thermoplastic plastic coating layer 4 and the steel sheet pile 1 with factors that promote peeling, such as water or seawater, and the low-rigidity and high-elasticity Therefore, it can easily follow deformations such as contraction and expansion in the plane direction of the thermoplastic plastic coating layer 4, and the edge releasability can be greatly improved. The highest corrosion protection effect can be obtained by applying a specific treatment to the edge of the thermoplastic plastic layer and then providing the low-rigidity, high-modulus elastomer coating layer 5. Methods include (1) activating the surface with corona discharge treatment, etc., (2) applying uneven processing such as embossing (third step).
(3) Continuously reduce the thickness of the thermoplastic coating layer outwards (see Figure 4); (4) Turn over the adhesive thermoplastic layer or apply a new coating. at least one of the following four types of treatments:
The feature is that after processing, a low-rigidity, high-elasticity elastomer is continuously coated. In addition, when carrying out the treatment in (1), it is preferable that the surface tension is in the range of 0.04 to 0.08 N/m,
In addition, when adopting method (2), the curvature
Preferably, Rz is approximately 50 μm to 1 mm. Furthermore, when carrying out method (3), preferable results can be obtained by applying an inclination of 10° to 60° to the steel sheet pile. In the present invention, there is no reason to particularly limit the thickness of the coating layers 4, 2, and 3, but considering various performances, workability, economical, etc., the thicknesses are 0.5 to 5 mm and 10 to 5 mm, respectively.
Preferable results can be obtained when the thickness is 100 μm or 0.05 to 1.0 mm. In addition, in the method of the present invention, it is possible to form the covering layer 5 without subjecting the covering layer 5 to the above-mentioned treatment/processing, but in this case, since the bond between the two materials lacks long-term stability. Preferably avoided. Hereinafter, the structure and effects of the present invention will be explained in more detail based on Examples. [Example] A panel method was employed to examine the effect of anticorrosion treatment applied to the thermoplastic plastic coating layer 4. Test panel: 240 x 240 x 9 mm Hot rolled steel plate Treatment: Sandblasting and chromic acid treatment Coating: Coating layer 4 High density polyethylene (150 x 150 x 1.7
mm) Coating portion 5 Oxime-free polyurethane elastomer composition coating layer 2 A bisphenol-type epoxy compound cured with an amine curing agent (film thickness 50 μm)
m) Coating layer 3 Polyethylene grafted with carboxylic acid anhydride (150 x 150 x 0.3 mm) End treatment of coating layer 4 (1) Corona discharge treatment (surface tension 0.06 N/m) (2) Embossing Processing (Rz=200μm) (3) Cut the edges at 30° (4) Press the sheet of coating d again (5) Comparative example: untreated example, unprocessed Five types of coatings prepared as above Salt water spray resistance (5% salt water at 35℃) for steel plates.
We investigated the behavior of each sample in terms of spraying for 2,500, 5,000, and 10,000 hours) and thermal shock resistance (repetitive heating and cooling tests at 0°C and 60°C for 2 hours/cycle, conducted in 5% saline for 50 and 100 cycles). The results shown in the following table were obtained.

〔Effect of the invention〕

By using the steel sheet pile of the present invention, it is possible to expect a high-performance corrosion prevention effect that cannot be obtained with conventional steel sheet piles, and therefore, high-quality construction can be provided in construction using this. .

[Brief explanation of the drawing]

1 and 2 are partial cross-sectional views of steel sheet piles subjected to anticorrosion treatment according to the present invention, and FIGS. 3 to 5 are enlarged cross-sectional views of the ends of steel sheet piles. DESCRIPTION OF SYMBOLS 1... Steel sheet pile, 2... Thermosetting plastic coating layer, 3... Adhesive thermoplastic plastic layer, 4
...Thermoplastic plastic covering part, 5...Low rigidity, high elasticity elastomer covering part.

Claims (1)

[Claims] 1. A thermoplastic coating layer is formed on the thermosetting plastic coating layer formed on the surface of the steel sheet pile through an adhesive thermoplastic coating layer, and each of these coating layers is A low-rigidity, high-modulus elastomer coating section is provided so as to span the end portion and the surface of the steel sheet pile, and peeling prevention treatment is applied to the contact surface of the end portion of each of the coating layers with the low-rigidity, high-modulus elastomer coating section. A plastic-coated steel sheet pile characterized by: 2. The plastic-coated steel sheet pile according to claim 1, wherein at least one of the following treatments is applied as the peeling prevention treatment. Surface activation by corona discharge, etc. Uneven processing by embossing etc. The thicknesses of the adhesive thermoplastic coating layer and the top thermoplastic coating layer are continuously decreased outwardly. An adhesive thermoplastic plastic coating layer is formed on the outer surface of the end portion of the thermosetting plastic coating layer.