JPH0730547B2 - Colored polyolefin coated steel pipe pile - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin-coated steel pipe pile for use in steel structures such as foundation piles used in the ocean, rivers and harbors. More specifically, the polyolefin coating has various colors and is excellent in appearance. The present invention also relates to a polyolefin-coated steel pipe pile which prevents the occurrence of cracks on the coated surface due to light and has excellent corrosion resistance.

[0002]

2. Description of the Related Art A conventional polyolefin-coated steel pipe pile uses a polyolefin such as black polyethylene or polypropylene which is excellent in corrosion resistance. However, due to the recent growing market needs for the beauty of steel structures in cityscapes, rivers, and ports, it is desired to develop polyolefin-coated steel pipe piles that are colored in various colors, are in harmony with the environment, and have excellent corrosion resistance. There is. For such needs, a method of coating a steel pipe with a colored polyolefin to which various coloring pigments are added can be applied.

[0003]

However, in such a conventional steel pipe pile coated with a colored polyolefin,
When it is exposed to ultraviolet rays for a long period of time, cracks are generated on the surface of the colored polyolefin coating and the anticorrosion property is impaired. For example, in an ultraviolet deterioration acceleration test using a sunshine weatherometer, which is one of the weather resistance acceleration tests, a crack is generated from the surface of the coating in a test of about 8000 hours, and the crack gradually progresses to the inside, so that the corrosion resistance is improved. Be damaged. As described above, it is difficult to obtain a colored polyolefin-coated steel pipe pile excellent in both aesthetics and anticorrosion by using the conventional technique, and it is possible to prevent the occurrence of cracks in the colored polyolefin coating due to ultraviolet rays, which is a cause of impairing anticorrosion. is necessary.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that carbon black is an essential component through a modified polyolefin adhesive layer on the outer surface of a steel pipe that has been subjected to a base treatment. Laminate a polyolefin anticorrosion layer with a specific hindered amine ultraviolet stabilizer, a specific benzotriazole ultraviolet absorber, a specific hindered phenolic antioxidant and a colored polyolefin layer containing four pigments as essential components. The inventors have found that the above-mentioned problems can be solved by the above, and have reached the present invention.

That is, according to the present invention, as shown in FIG. 1, for example, a chromate coating 2 is formed on the outer surface of a blasted steel pipe 1.
And an epoxy primer layer 3 are sequentially laminated and subjected to a base treatment, and a polyolefin anticorrosion layer 5 containing carbon black as an essential component and a specific hindered amine ultraviolet stabilizer, a specific A polyolefin-coated steel pipe pile, comprising a laminated colored polyolefin layer 6 containing four components of a benzotriazole-based ultraviolet absorber, a specific hindered phenol-based antioxidant and a coloring pigment as essential components.

The present invention will be described in detail below.

The steel pipe used in the present invention is a steel pipe made of alloy steel such as carbon steel and stainless steel. Further, for the purpose of improving the corrosion resistance of the steel pipe, the outer surface and the inner surface of the steel pipe are plated with zinc, aluminum, chromium or the like, zinc-iron, zinc-aluminum, zinc-nickel or other alloy plating, silica or oxide in the plating or alloy plating. It is also possible to use a material that has been subjected to dispersion plating in which inorganic particles such as titanium are dispersed.

As the surface treatment of the steel pipe, the outer surface of the steel pipe is blasted by grit blasting, sand blasting or the like to remove rust, and then chromate treatment and an epoxy primer are applied and cured to subject the steel pipe to the surface treatment. After coating a modified polyolefin adhesive modified with an acid or the like, a coated steel pipe pile in which a polyolefin anticorrosive layer and a colored polyolefin layer of the present invention are laminated and coated is used, but from the skeleton of the present invention, the present invention is applied to the surface of the coated steel pipe pile. It suffices that the polyolefin anticorrosion layer and the colored polyolefin layer are firmly adhered / coated, and the conventionally known chromate treatment agent, epoxy primer, phosphate treatment agent, silane coupling treatment alone, or these base treatments are used for the base treatment. Combinations of treatments can also be used.

As the polyolefin used for forming the modified polyolefin adhesive layer, the polyolefin anticorrosive layer and the colored polyolefin layer of the present invention, polyethylene, polypropylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexane, A copolymer of α-olefin such as 1-octene and ethylene is used.

As the modified polyolefin adhesive, a modified polyolefin obtained by modifying a polyolefin with an acid anhydride such as maleic anhydride, a modified polyolefin prepared by adding an elastomer such as ethylene-propylene rubber to a polyolefin with an acid anhydride, or Adhesives obtained by diluting these modified polyolefins with polyolefins are used, but polyolefin-based adhesives other than these can also be used.

A polyolefin anticorrosion layer containing the carbon black of the present invention as an essential component between the colored polyolefin layer and the modified polyolefin adhesive layer in order to prevent the generation of cracks in the colored polyolefin layer and the progress of the cracks to the inside due to ultraviolet rays. is necessary. The reason why the generation of cracks in the colored polyolefin layer is prevented by adding carbon black to the polyolefin anticorrosion layer is unknown, but the effect is that carbon black is added to the polyolefin anticorrosion layer in an amount of 0.
It develops when added in the range of 1 to 5% by weight. In addition, a pigment other than carbon black, for example, an inorganic pigment such as titanium oxide, talc, or mica may be added to the polyolefin anticorrosion layer in order to provide color matching and strength.

In order to prevent cracking of the colored polyolefin layer due to ultraviolet rays, it is essential that the colored polyolefin layer contains four components: a hindered amine ultraviolet stabilizer, a benzotriazole ultraviolet absorber, a hindered phenolic antioxidant and a colored pigment. Add as an ingredient. As a hindered amine-based UV stabilizer added to the colored polyolefin layer, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl} {2 2,6,6-Tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}]

[0013]

[Chemical 1]

Or bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate

[0015]

[Chemical 2]

Is used.

As a benzotriazole type ultraviolet absorber, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole is used.

[0018]

[Chemical 3]

Or 2- (3,5-di-t-butyl-2
-Hydroxyphenyl) -5-chlorobenzotriazole

[0020]

[Chemical 4]

Is used. 1,3,5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene as a hindered phenolic antioxidant

[0022]

[Chemical 5]

Is used. In order to prevent cracking of the colored polyolefin layer due to ultraviolet rays, 0.05 to 2% by weight of a hindered amine ultraviolet stabilizer, 0.05 to 2% by weight of a benzotriazole ultraviolet absorber, and a hindered phenolic antioxidant. It is necessary to add 0.05 to 2 wt% of each. When one of these hindered amine-based UV stabilizers, benzotriazole-based UV absorbers, or hindered phenol-based antioxidants is lacking, long-term UV irradiation causes cracks in the colored polyolefin layer. Also, when a hindered amine-based UV stabilizer, a benzotriazole-based UV absorber, or a hindered phenol-based antioxidant other than these is used, the colored polyolefin layer is cracked by long-term UV irradiation. It is necessary to add various coloring pigments to the colored polyolefin layer in order to impart a beautiful appearance.
Color pigments to be added include commercially available inorganic pigments such as titanium oxide, iron oxide black, titanium yellow, various baked pigments, and organic pigments such as phthalocyanine green, phthalocyanine blue, quinacridone red, perinoso orange, and isoindolino yellow. Then, one or more of these pigments are mixed to prepare a color.

Next, a method for manufacturing the colored polyolefin-coated steel pipe pile of the present invention will be described.

The outer surface of the steel pipe is grit blasted, coated with a chromate treatment agent, and baked. Next, an epoxy primer is applied to the surface, heated and cured, and the modified polyolefin adhesive is immediately electrostatically powder coated and melted. The polyolefin anticorrosive layer of the present invention and the colored polyolefin are coextrusion coated on the surface from a two-layer T die and water-cooled to produce the colored polyolefin-coated steel pipe pile of the present invention. The coating method of the chromate treatment agent is roll coating, brush coating,
Conventionally known methods such as ironing with various brushes can be used. As a method for applying the epoxy primer, a conventionally known method such as spray application, ironing with a rubber ring or a rubber spatula can be used. The modified polyolefin adhesive, the polyolefin anticorrosive layer, and the colored polyolefin layer are coated by a single-layer T die or a single-layer round die by extrusion coating each layer separately, and a modified polyolefin layer and a polyolefin anticorrosive layer are two-layer T-die. Or a method in which two layers are extrusion-coated with a round die and then a colored polyolefin layer is extrusion-coated with a single-layer T die or a single-layer round die,
It is possible to use a method in which the modified polyolefin adhesive layer, the polyolefin anticorrosive layer, and the colored polyolefin layer are extrusion-coated in a three-layer integral manner.

[0026]

The colored polyolefin-coated steel pipe pile of the present invention, as shown in FIG. 1, has a chromate coating 2 and an epoxy primer layer 3 successively laminated on the outer surface of a blast-treated steel pipe 1 and subjected to a base treatment, and the surface thereof is a modified polyolefin. Through the adhesive layer 4, a polyolefin anticorrosive layer 5 containing carbon black as an essential component, a specific hindered amine-based UV stabilizer, a specific benzotriazole-based UV absorber, a specific hindered phenol-based antioxidant and a coloring pigment A polyolefin-coated steel pipe pile, characterized in that a colored polyolefin layer 6 comprising four components as essential components is laminated. 2 in the figure is 200 to 1500 mg / m in terms of the total chromium deposition amount.
² adhesion amount, 3 is 10 to 150 μm film thickness, 4 is 100
Good results are obtained with a film thickness of ˜500 μm, 5 having a film thickness of 0.5 to 8 mm and 6 having a film thickness of 0.2 to 5 mm.

The present invention will be described below based on examples.

[0028]

【Example】

(Example) Outer diameter 200A x length 5000mm x wall thickness 3.
The outer surface of a 2 mm steel pipe is grit blasted to remove rust, and the chromate treatment agent has a total chromium adhesion of 600 mg /
It was coated so that it had a surface area of m ² , and heated to 160 ° C. and baked.
While the chromate-treated steel pipe was being transferred and conveyed on a V roll, an epoxy primer was ironed and applied to the surface thereof through a rubber ring so as to have a film thickness of 50 μm, and heated at 190 ° C. by high frequency induction heating to be cured. Then, a modified polyolefin adhesive on its surface by a three-layer round die,
The test tubes 1 to 24 of the polyolefin-coated steel pipe pile of the present invention were manufactured by extrusion-coating three layers of a polyolefin and a colored polyolefin for a polyolefin anticorrosion layer, followed by water cooling. Tables 1 to 4 show the contents of the modified polyolefin adhesive, the polyolefin for the polyolefin anticorrosion layer and the colored polyolefin used, and the hindered amine ultraviolet stabilizer, benzotriazole ultraviolet absorber and hindered phenol antioxidant added to the colored polyolefin. Is shown in Table 5. The thickness of the modified polyolefin adhesive layer is 200μ
m, the thickness of the polyolefin anticorrosive layer was 2 mm, and the thickness of the colored polyolefin layer was 1 mm. These colored polyolefin coated steel pipe piles of the present invention are cut to 70 mm width × 150 mm length × 3.2 mm.
The cut plates having a thickness were irradiated with ultraviolet rays using a carbon arc lamp type sunshine weatherometer [black panel temperature: 63 ° C., relative humidity 50%], and the presence or absence of cracks on the surface was examined. The test time of the test was 10,000 hours. The results are collectively shown in Tables 1 to 4.

As is clear from the results of Tables 1 to 4, a polyolefin anticorrosive layer containing the carbon black of the present invention as an essential component and a hindered amine ultraviolet stabilizer,
A colored polyolefin-coated steel pipe pile laminated and coated with a colored polyolefin layer containing four components of a benzotriazole-based ultraviolet absorber, a hindered phenol-based antioxidant, and a coloring pigment as essential components is a 10,000-hour accelerated test using a sunshine weatherometer. Even after that, since no crack is generated on the surface of the colored polyolefin coating, the anticorrosion property is extremely excellent.

(Comparative Example) In the same manner as in the Example, a comparative colored polyolefin coated steel pipe pile 1 lacking a polyolefin anticorrosion layer, a comparative colored polyolefin coated steel pipe pile 2 lacking carbon black in the polyolefin anticorrosion layer, and a hindered amine type ultraviolet ray in the colored polyolefin layer. Comparative colored polyolefin coated steel pipe pile 3 lacking stabilizer, comparative colored polyolefin coated steel pipe pile 4 whose colored polyolefin layer lacks benzotriazole type UV absorber, comparative colored polyolefin coated steel pipe whose colored polyolefin layer lacks hindered phenolic antioxidant Piles 5 and Comparative colored polyolefin coated steel pipe piles 6 to 8 in which the hindered amine ultraviolet stabilizer of the colored polyolefin layer was changed to a hindered amine ultraviolet stabilizer other than the present invention, and benzotriazole ultraviolet absorption of the colored polyolefin layer Was changed to a benzotriazole-based UV absorber other than the present invention. Comparative colored polyolefin-coated steel pipe piles 9 to 11, and the hindered phenol-based antioxidant of the colored polyolefin layer was changed to a hindered-phenol-based antioxidant other than the present invention. Comparative colored polyolefin coated steel pipe piles 12-14 were each manufactured. Table 5 shows hindered amine ultraviolet stabilizers, benzotriazole ultraviolet absorbers and hindered phenol antioxidants added to the colored polyolefin.

These comparatively colored polyolefin-coated steel pipe piles were cut into test tubes to obtain 70 mm width × 150 mm length × 3.2 mm thickness cutting plates, and a carbon arc lamp type sunshine weatherometer [black panel temperature: 6] was used.
These cut plates were irradiated with ultraviolet rays at 3 ° C. and a relative humidity of 50%], and the presence or absence of cracks from the surface was examined. The test time of the test was 10,000 hours. The results are shown in Tables 1 to 4
It is shown collectively.

As is clear from the results of Tables 1 to 4, when the polyolefin anticorrosion layer containing carbon black, which is one of the essential constituents of the present invention, is lacking, when the polyolefin anticorrosion layer lacks carbon black, coloring If the polyolefin layer lacks the hindered amine UV stabilizer, the benzotriazole UV absorber or the hindered phenolic antioxidant of the present invention, or if a different type from the present invention is used, the sunshine weatherometer accelerates for 10,000 hours. After the test, cracks are generated on the surface of the colored polyolefin coating, and the anticorrosion property deteriorates.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

As is clear from the above examples, a polyolefin anticorrosion layer containing carbon black as an essential component and a hindered amine-based ultraviolet ray on the outer surface of a steel pipe which has been subjected to a base treatment through a modified polyolefin adhesive layer. The colored polyolefin-coated steel pipe pile of the present invention in which a colored polyolefin layer containing four components of a stabilizer, a benzotriazole-based ultraviolet absorber, a hindered phenol-based antioxidant, and a coloring pigment as essential components is sequentially laminated is a colored polyolefin by ultraviolet rays. Since it prevents the occurrence of cracks in the coating and the progress of the cracks into the interior, it exhibits unprecedented excellent corrosion resistance and is excellent in aesthetics.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an example of a colored polyolefin-coated steel pipe pile of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Blast-treated steel pipe 2 ... Chromate film 3 ... Epoxy primer film 4 ... Modified polyolefin adhesive layer 5 ... Polyolefin anticorrosion layer containing carbon black as an essential component 6 ... Hindered amine ultraviolet stabilizer, benzotriazole ultraviolet absorption Polyolefin layer containing 4 components of an agent, a hindered phenolic antioxidant and a color pigment as essential components

Claims (3)

[Claims] 1. A polyolefin anticorrosion layer containing carbon black as an essential component on the outer surface of a steel pipe which has been subjected to a base treatment, through a modified polyolefin adhesive layer, and
Polyolefin-coated steel pipe pile characterized by sequentially laminating colored polyolefin layers containing the above components as essential components Hindered amine UV stabilizers Benzotriazole UV absorbers Hindered phenol antioxidants Colored pigments 2. A hindered amine UV stabilizer is poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl} {2.
2,6,6-Tetramethyl-4-piperidyl) imino}
Hexamethylene {(2,2,6,6-tetramethyl-4
-Piperidyl) imino}] or bis (2,2,6,6
-Tetramethyl-4-piperidyl) sebacate and the benzotriazole-based UV absorber is 2- (3
-T-butyl-5-methyl-2-hydroxyphenyl)
-5-chlorobenzotriazole or 2- (3,5-
Di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole and the hindered phenolic antioxidant is 1,3,5-trimethyl-2,4.
The polyolefin-coated steel pipe pile according to claim 1, which is 6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene. 3. The polyolefin-coated steel pipe pile according to claim 1, wherein a chromate film and an epoxy primer layer are sequentially laminated on the outer surface of the steel pipe that has been subjected to blasting as a base treatment for the steel pipe.