JPH06198805A - Colored polyethylene coating material excellent in weatherability - Google Patents

Abstract

PURPOSE:To ensure the long-term weatherability of a polyethylene heavy corrosion-proof coated, steel material without adding a deterioration inhibitor. CONSTITUTION:A resin layer formed by laminating a colored polyethylene layer with a thickness of 10-200mum containing color pigment on a thick corrosion-proof polyethylene layer containing 0.5wt.% or more of carbon black is applied to the surface of a steel material through an adhesive layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy anticorrosion coated steel material in which the surface of a base material such as steel material is coated with a thick film anticorrosion polyethylene layer,
For example, the present invention relates to a heavy-duty anticorrosion coated steel pipe resistance, a steel pipe sheet pile, a steel sheet pile and the like, and more particularly to a colored polyethylene-coated steel material having excellent weather resistance and having a surface coated with a colored polyethylene layer.

[0002]

2. Description of the Related Art Steel materials used outdoors for a long time may be exposed to a severe corrosive environment. For example, steel sheet piles and steel pipe sheet piles are continuously driven into the ground to form protective fences, mainly for the purpose of reveting rivers, coasts, harbors, etc. Has been used for. Steel pipes are also often used as gas pipes and water pipes.

These steel materials are used in the outdoor natural environment.
It is exposed to water such as river water, drainage, rainwater, and seawater, the atmosphere, sunlight, and is in direct contact with earth and sand, mud, and rubble. Therefore, for a long time (about 40
(Year) effective anticorrosion measures were desired.

In recent years, as a countermeasure against this, a resin is thick film (1-
3mm) Heavy anticorrosion coated steel is being used because of its excellent anticorrosion property. As this coating resin,
Polyethylene is often used in consideration of economy and various characteristics.

However, the polyethylene resin is apt to deteriorate due to the influence of ultraviolet rays contained in sunlight, and therefore, when used outdoors as in this application, carbon black 1
Generally, about 3% by weight is added to improve weather resistance, and the color tone is limited to black. However, in a place where a living environment or a natural environment should be comfortably and neatly maintained, it is required to color steel sheet piles, steel pipe sheet piles, steel pipes for piping, etc. so as to suit the environment.

Therefore, a colored polyethylene-coated steel material has been proposed in which polyethylene is added with various deterioration inhibitors such as an ultraviolet absorber and an antioxidant in place of carbon black as a measure against ultraviolet deterioration and then colored with a coloring pigment.

As such deterioration inhibitors, substances represented by benzotriazole compounds that convert ultraviolet rays into low energy (ultraviolet absorbers), hindered amine light stabilizers and hinders generally abbreviated as HALS. Examples include antioxidants such as dephenol compounds and sulfur compounds. In the present specification, additives effective for improving weather resistance such as an ultraviolet absorber, a light stabilizer, and an antioxidant are collectively referred to as a deterioration inhibitor.

The additive formulation of these deterioration inhibitors is as follows:
A method of adding an ultraviolet absorber and a phenolic antioxidant and / or carbon black (Japanese Patent Laid-Open No. 63-60712).
No.) is known, but even if a UV absorber and a phenolic antioxidant are combined and blended in a polyethylene resin, weather resistance of about 15 years (3000 hours at a sunshine weather meter black panel temperature of 63 ° C.) is obtained. It didn't pass.

Also, an uncolored polyethylene anticorrosion layer (1 mm
(Thickness), 0.1% by weight or more of antioxidant and weather resistance stabilizer
Colored polyethylene anticorrosion layer containing 0.3% by weight or more
A heavy-duty anticorrosion coated steel pipe in which only a polyethylene-coated surface layer is colored coating layer by fusing (0.4 mm thickness) is also proposed (JP-A-4-80029). However, even if the deterioration preventing agent is added to the polyethylene of the surface layer as described above,
It has a weather resistance of about 25 years (5000 hours at a sunshine weather meter black panel temperature of 63 ° C). in this way,
The color-coated steel materials that have been proposed so far are all about 40 years old.
(Sunshine weather meter black panel temperature 63
It was insufficient to obtain long-term weather resistance of 8,000 hours at ℃.

[0010]

In order to improve the weather resistance, it may be effective to increase the compounding amount of the deterioration preventing agent, but these deterioration preventing agents are expensive and the base polyethylene resin is used. The price is at least several times higher than that of, and the increase in the compounding price causes a rise in the product cost. In particular, the outer surface coating of outdoor pipes such as water and gas, steel pipe resistance,
In heavy-duty anticorrosion coatings for steel sheet piles, steel pipe sheet piles, etc., the production scale is large, so the addition of deterioration inhibitors increases, and excessive addition of deterioration inhibitors impairs the economic efficiency of the product.

An object of the present invention is to provide a steel material such as a steel sheet pile, a steel pipe sheet pile and a steel pipe with a long-term weather resistance of at least about 40 years without impairing the economical efficiency and without adding a deterioration inhibitor. A colored polyethylene-coated steel material provided with a colored polyethylene coating is provided.

[0012]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventors have found that long-term weather resistance of about 40 years can be ensured without using a large amount of deterioration inhibitor. It was concluded that the addition of carbon black to the anticorrosion layer is essential. Therefore, in order to achieve the purpose by the colored polyethylene coating in which the colored polyethylene layer containing the colored pigment is laminated on the polyethylene anticorrosive layer containing carbon black, the weather resistance of the laminated polyethylene coating was examined.

As a result, if 0.5% by weight or more of carbon black is added to the lower polyethylene of the anticorrosion layer and the thickness of the upper colored polyethylene layer is reduced to 10 to 200 μm, the surface of the colored polyethylene layer becomes a problem in appearance. It was found that, although fine cracks that do not occur are generated, the weather resistance is not substantially reduced due to the cracks, and long-term weather resistance of about 40 years can be achieved as a whole coating.

In the present invention, carbon black is added to 0.5
A resin layer obtained by laminating a colored polyethylene layer containing a coloring pigment and having a thickness of 10 to 200 μm on an anticorrosion polyethylene layer containing at least 10% by weight is coated on the surface of the base material via an adhesive layer. A colored polyethylene coating material, which is characterized in that

[0015]

In the present invention, the base material to which the polyethylene coating is applied is generally a steel material, but the material of the base material is not limited to steel, but other metal materials such as aluminum, as well as stone materials and wood materials. , Ceramics, etc. are also possible. Hereinafter, a case where a steel material, which is a typical material, is used as a base material will be described, but the same applies when a base material other than steel is used. The shape of the steel material (or the base material) is not particularly limited, and may be a tubular material such as a steel pipe or a steel pipe resistance,
A plate material such as a steel sheet pile, a steel bar, or a deformed material may be used. It is desirable to clean the surface of the steel material in advance by appropriately combining physical means such as shot blasting and chemical means such as pickling and alkaline degreasing.

The steel material may be subjected to plating and / or chemical conversion treatment (chromate treatment, zinc phosphate treatment) as a base treatment for improving the adhesion and the corrosion resistance. Also,
The surface of the steel material may be pretreated with a suitable primer in order to enhance the adhesion of the polyethylene layer. As the primer, for example, an epoxy primer or the like can be used. The primer is applied thinly and then dried or is irradiated with ultraviolet rays to be cured. These base treatments can be carried out in the same manner as in the conventional case, if necessary.

Since the polyethylene resin has a relatively low adhesiveness, an adhesive layer is interposed at the interface between the steel material and the resin layer, and the resin layer is coated on the steel material via the adhesive agent. A maleic anhydride-modified polyethylene resin is a preferred adhesive because it exhibits particularly high adhesiveness. In addition, adhesives based on ethylene copolymers (eg, ethylene / vinyl acetate copolymers) and polyethylene hot melt adhesives can also be used. The thickness of the adhesive layer is not particularly limited and varies depending on the type of adhesive, but is generally about 0.1 to 0.5 mm.

The resin layer coated on the steel material according to the present invention is
It is a resin layer formed by laminating a thick film anticorrosion polyethylene layer containing carbon black and a thin colored polyethylene layer serving as a surface layer.

The thickness of the lower anticorrosion polyethylene layer is not particularly limited as long as it is sufficient as the anticorrosion layer.
Generally, it is 0.5 to 5 mm. In order to realize long-term weather resistance of about 40 years, it is preferable that the range is 2-3 mm. The polyethylene resin used may be high density, medium density or low density polyethylene, with a small amount of other olefin or vinyl monomers (eg, propylene, vinyl acetate, acrylic acid, acrylate, etc.) being copolymerized. Good.

The anticorrosion polyethylene layer (anticorrosion layer) is a black resin layer containing carbon black in an amount of 0.5% by weight or more. When the content of carbon black is less than 0.5% by weight, a sufficient ultraviolet ray shielding effect cannot be obtained, surface deterioration proceeds to the anticorrosion layer, and the physical properties of the entire coating resin layer are significantly deteriorated. On the other hand, excessive addition of carbon black lowers the economical efficiency and mechanical properties of the product, so the upper limit of the carbon black content is preferably 5% by weight.

Since carbon black alone imparts sufficient weather resistance to the anticorrosion layer, it is not necessary to add other deterioration inhibitors such as antioxidants and ultraviolet absorbers to the anticorrosion layer in addition to carbon black. However, if desired, a small amount of a deterioration inhibitor may be added to the anticorrosion layer together with carbon black.

Colored polyethylene layer as a surface layer (colored layer)
The polyethylene resin may be the same as the anticorrosion layer. The thickness of the colored layer is 10 to 200 μm, and preferably 30 to 150 μm in order to realize long-term weather resistance. If the thickness of the colored layer is less than 10 μm, it is difficult to eliminate the black color of the anticorrosion layer, and the colored polyethylene layer on the surface becomes dark, which is not preferable. If the thickness of the colored layer exceeds 200 μm, the depth and size of surface cracks that occur due to surface deterioration are proportional to the thickness of the colored layer, so the physical properties of the entire resin coating layer including the anticorrosion layer will crack after surface deterioration. Will be significantly reduced by.
Also, since the cracks become large, the appearance also deteriorates. On the other hand, when the thickness of the colored layer is in the range of 10 to 200 μm, particularly 30 to 150 μm, the black color of the anticorrosion layer containing carbon black can be easily erased, and the cracks generated even after the surface deterioration is generated. Limited to the surface layer only. As a result, cracks do not become large, the physical properties of the entire resin coating layer including the anticorrosion layer do not deteriorate, and long-term weather resistance can be maintained.

The coloring pigment for coloring the polyethylene resin may be any known organic or inorganic pigment. Specifically, organic pigments such as azo, anthraquinone, phthalocyanine, quinacridone, isoindolinone, dioxazine, perinone, quinophthalone, and perylene pigments, ultramarine blue, titanium dioxide, and iron oxide.
Inorganic pigments such as (valve pattern), chromium oxide, and carbon black can be used.

The blending amount of the coloring pigment is not limited as long as it is an amount sufficient for coloring and varies depending on the type of pigment, but it is generally based on 100 parts by weight of the polyethylene resin.
It will be in the range of 0.1 to 5 parts by weight. In addition to color pigments,
One or more known additives such as extender pigments, rust preventive pigments, dispersants, softeners and flame retardants may be further added. These additives can also be added to the anticorrosion layer.

Since long-term weather resistance can be secured without adding a deterioration inhibitor to the colored layer, it is not always necessary to add a deterioration inhibitor to the colored layer. However, when the deterioration preventing agent is added to the colored layer, the time until the generation of surface fine cracks is extended. Therefore, if desired, one or more known deterioration inhibitors may be added to the colored layer, whereby the weather resistance can be further improved. However, even in that case, it is difficult to completely prevent surface cracks.
Further, excessive addition of the deterioration inhibitor not only impairs the economical efficiency of the product, but also causes bleed-out of the deterioration inhibitor in some cases, leading to deterioration in quality. Therefore, when adding a deterioration inhibitor, the total addition amount is polyethylene resin.
It is preferably 2 parts by weight or less with respect to 100 parts by weight.

When the colored polyethylene resin used for the colored layer is produced, the colored pigment is added in an amount of 3 to 50 in the polyethylene resin.
Prepare a masterbatch containing about 10% by weight and prepare a colored polyethylene resin composition by mixing the masterbatch and a polyethylene resin containing no pigment at a predetermined ratio. , Economically advantageous.

The colored polyethylene coating comprising a laminate of the thick film anticorrosive layer and the thin film colored layer of the present invention has carbon black added to the anticorrosive layer, which occupies most of the layer, so that the colored layer on the surface is not always expensive. The desired long-term weather resistance of about 40 years can be exhibited without adding a deterioration inhibitor. This makes it possible to inexpensively obtain a polyethylene coating whose surface can be colored in any color according to the use environment and which exhibits long-term weather resistance.

The colored polyethylene-coated heavy corrosion-resistant steel material of the present invention is manufactured by coating the steel material with the colored polyethylene coating via an adhesive layer, for example, by the method described below. The polyethylene resin coating may be applied only to the surface of the steel material that requires corrosion protection, and does not necessarily have to cover the entire surface.

As a method for coating the steel material with polyethylene, for example, the following method is possible. A: Method based on melt extrusion method, B: Method based on electrostatic powder method, C: Method based on fluidized immersion method, D: Method based on thermal spraying method, E: Sheet laminating method Based on the method.

In each of the methods A to D, the surface of the steel material is cleaned by pickling or blasting, preheated to about 120 to 300 ° C. by an appropriate heating means such as induction heating, and then the adhesive resin.
This can be carried out by coating the surface of the steel material with a thin film of (eg, maleic anhydride-modified polyethylene resin) by any of the methods A to D. Next, while the adhesive resin is still in a molten state, a polyethylene resin containing carbon black is coated on the adhesive layer in any one of A to D, and the anticorrosive layer is in a molten state. During the period, the colored layer made of polyethylene resin containing the colored pigment is coated on the anticorrosion layer by any one of the methods A to D. Adhesive resin,
The anticorrosive layer and the colored layer can be coated by different methods, but the method of coating by the same method is usually easy to manufacture.

In the laminating method of E, a film of an adhesive resin, a carbon black-containing polyethylene sheet serving as an anticorrosion layer, and a colored polyethylene film serving as a coloring layer are prepared, and these three layers are separately or previously laminated, Laminate on the surface of the washed preheated steel with the adhesive layer on the inside. In a more preferred method, a three-layer coextrusion method or an extrusion laminating method is used to form a multilayer sheet consisting of three layers of an adhesive layer, an anticorrosive layer, and a colored layer, and the adhesive is placed inside to form a multilayer sheet. Simultaneously with or after the formation, it is laminated on the surface of the steel material.

The coating method may be appropriately selected depending on the shape of the coated surface of the steel material. For example, in the case of a relatively simple shape such as a steel sheet pile or a steel pipe, any of the above methods A to E can be applied. In the case of a slightly complicated shape such as a steel pipe sheet pile, the methods of BD may be more suitable.

Steel products (eg, steel sheet piles, steel pipes, etc.) which are heavily anticorrosive coated with a black polyethylene layer containing 0.5% by weight or more of carbon black are already on the market. Using such a product (or another steel material already coated with an anticorrosion layer) as the base material, heat it to about 80 ° C to soften the polyethylene anticorrosion coating, and then apply the colored polyethylene layer to
It is also possible to carry out extrusion coating at 0 to 250 ° C to produce the colored polyethylene-coated steel material of the present invention. This reduces the amount of resin exchange in the extruder, which is economically advantageous.

[0034]

[Example] The surface of a steel sheet pile (Sumitomo Metal Co., Ltd .; SKSP-II type) was subjected to shot blasting to adjust the substrate (Sa. 2.
After that, a chromate treatment was performed using a coating type chromate solution (manufactured by Kansai Paint Co., Ltd .; Cosmer 100) so that the amount of deposited chromium was 200 mg / m ² . Epoxy primer (made by Nippon Paint Co., Ltd .;
No. 66 primer) was applied to a dry film thickness of 30 μm, and the steel material was heated to 190 ° C. by using an induction heating device to bake the primer and preheat the steel material.

On the other hand, as a resin for the anticorrosion layer to be coated, a medium- and low-pressure polyethylene resin (Showa Denko; Sholex S4
002 EX) was mixed with carbon black in an addition amount shown in Table 1 to prepare a carbon black-containing polyethylene resin composition. The resin composition of the colored layer was the same as that of the anticorrosion layer, which was obtained by adding the pigments shown in Table 1 to the polyethylene resin of the medium and low pressure method (the addition amount was 0.1 to 3 parts by weight based on 100 parts by weight of the resin) and melt-kneading. .

Maleic anhydride-modified polyethylene (Admer manufactured by Mitsui Petrochemical Co., Ltd.) to be an adhesive layer is extruded together with the above-mentioned anticorrosion layer polyethylene resin composition and colored layer polyethylene resin composition in three layers to form an adhesive layer / anticorrosion layer. A multi-layer polyethylene sheet having a width of 900 mm and including three colored layers was obtained. The thickness of this sheet was 0.3 mm for the adhesive layer, and the thicknesses of the anticorrosion layer and the coloring layer were as shown in Table 1. After heating this sheet to about 80 ° C with an infrared heater, the modified polyethylene resin is fused and covered while pressing the convex portion of the preheated steel sheet pile to the steel sheet pile with a pressing roll, and the colored polyethylene-coated steel sheet pile is coated. Obtained.

Tensile elongation of the resin-coated portion of the colored polyethylene-coated steel sheet pile was measured by a sunshine weather meter (WOM accelerated weathering test) after 8000 hours at a black panel temperature of 63 ° C. (WOM 8000 hours is equivalent to about 40 years of actual environment). The retention rate was measured. The results are also shown in Table 1.

[0038]

[Table 1]

As can be seen from Table 1, in Examples 1 to 14 according to the present invention, the amount of carbon black added to the anticorrosion layer was 0.5% by weight or more, and the color layer had a thickness of 10 to 200 μm. In this case, the tensile elongation retention rate is WOM 80 even though neither the anticorrosion layer nor the coloring layer contains a deterioration inhibitor.
Almost no decrease after 00 hours. Even if the color tone is changed by changing the type of coloring pigment, if the thickness of the coloring layer is in the above range, the tensile elongation retention rate after WOM 8000 hours is almost 80%.
Maintained above, there was no significant decrease.

On the other hand, as can be seen from Comparative Examples 1 to 8, when the thickness of the colored layer was thicker than 200 μm, the tensile elongation retention rate after WOM 8000 hours was remarkably reduced to 20% or less. As shown in Comparative Example 9, when the thickness of the colored layer is less than 10 μm,
Although the tensile elongation retention did not decrease after WOM 8000 hours, the black color of the anticorrosion layer containing carbon black was transparent due to the thin thickness of the colored layer, and the appearance was darkened. In addition, as shown in Comparative Example 10, the amount of carbon black added to the anticorrosion layer
If it is less than 0.5% by weight, deterioration of the anticorrosion layer progresses, and as a result, the elongation retention rate after 8000 hours of WOM is remarkably lowered.

[0041]

As described above, the colored polyethylene-coated steel material of the present invention has a thick film anticorrosive layer containing 0.5% by weight or more of carbon black in polyethylene and a film thickness of 10 to 10% containing the coloring pigment in polyethylene. By laminating a 200 μm colored layer, it does not necessarily require addition of a deterioration inhibitor and exhibits a very long-term weather resistance of about 40 years, which has never been seen before.
Further, since the product can be colored directly, it is possible to greatly reduce the time required for resin exchange and the like. This makes it possible to use polyethylene-coated steel, which is colored freely according to the environment of use, outdoors for a long period of 40 years or more, and expands the range of applications to various materials such as steel sheet piles. , And the service life is extended. Therefore, the economic effect of the present invention is remarkable.

Claims (1)

[Claims] 1. A resin layer obtained by laminating a colored polyethylene layer containing a coloring pigment and having a film thickness of 10 to 200 μm on an anticorrosion polyethylene layer containing 0.5% by weight or more of carbon black, with an adhesive layer interposed therebetween. A colored polyethylene coating material characterized by being coated on the surface of a base material.