JPH03293426A - Steel tubular pile with heavy rustproof covering and its manufacture - Google Patents

Abstract

PURPOSE:To greatly raise the water-resistant adhesion between a color paint film and a heavy rustproof covering by a method in which a polyolefin-covered steel tube is treated by corona discharge and coated with a urethane primer and a fluoro resin paint. CONSTITUTION:A polyolefin-covered steel tube pile 3, having a polyolefin layer 2 containing 0.05-5.0wt.% antioxidant and having a thickness of 1-10mm on its outermost layer, is subjected to a corona-discharge treatment using roll electrodes 6 turning continuously. The pile 3 so treated is coated with a urethane primer or modified polyolefin primer 16 and with a color paint 4 such as various colors of fluoro resin paint, having a thickness of 10-100mum. The pile 1 so formed is free of blister in the fluoro resin paint film and has sufficiently high adhesion between the color paint film and the heavy rustproof covering. The water-resistant adhesion between the color paint film and the heavy rustproof covering can thus be greatly raised.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to heavy corrosion-resistant coated steel pipe piles used for steel structures such as foundation piles used in oceans, rivers, ports, etc. A heavy-duty anti-corrosion coated steel pipe pile that has a colored coating film in various colors with excellent weather resistance on its outer surface and has an excellent appearance, and has excellent water-resistant adhesion between the colored coating film and the heavy-duty anti-corrosion coating, and its manufacture. Regarding the law.

[Prior Art] Conventional polyolefin-coated steel pipe piles are coated with black polyethylene, which has excellent corrosion resistance. However, due to the recent increase in market needs for beautiful landscapes of steel structures such as urban landscapes, rivers, and ports, we have developed heavy-duty corrosion-resistant coated steel pipe piles that are colored in various colors to harmonize with the environment and have excellent weather resistance. is desired. To meet such needs, for example, as shown in FIG. 3, a urethane primer layer 14 and a fluororesin layer containing a colored pigment are added to the surface of a polyolefin-coated steel material having a polyolefin coating layer 13 subjected to flame treatment on the outer surface. There is a proposal for a heavy anti-corrosion coated steel material characterized by sequentially laminating layers of No. 15.

[Problems to be Solved by the Invention] However, in the conventional heavy anti-corrosion coated steel pipe pile shown in FIG. 15
The adhesive force between the fluororesin layer 15 containing the colored pigment tends to gradually decrease, and blisters tend to occur in the fluororesin layer 15 containing the colored pigment.Therefore, further improvement in water-resistant adhesiveness is desired.

[Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present inventors added 0.05 to 5.0% of an antioxidant to the outermost layer of the outer surface of the steel pipe.
0% by weight and whose outer surface has been treated with corona discharge treatment, or after applying a urethane primer or a modified polyolefin primer to the outer surface, fluorine-based paints of various colors, acrylic paints, etc. Silicone paint, acrylic
The inventors have discovered that the above-mentioned problems can be solved by laminating colored paint films such as urethane paints, leading to the present invention.

That is, as shown in FIG. 1, the present invention provides an outer polyolefin having a polyolefin 2 containing 0.05 to 5.0% by weight of an antioxidant in the outermost layer of the outer surface of a steel pipe 1 and having the outer surface treated with corona discharge. Fluorine-based paints of various colors, acrylic-silicon-based paints, acrylic-based paints are applied to the outer surface of coated steel pipe piles.
As shown in FIG. 2, there is a heavy anti-corrosion coated steel pipe pile characterized by laminating a colored paint film 4 such as urethane paint.
0.005 to 5.0% by weight of antioxidant in the outermost layer of the outer surface of the steel pipe
A steel pipe pile 3 coated with polyolefin on the outer surface containing polyolefin is subjected to a corona discharge treatment using a roll electrode 6 that continuously rotates the outer surface while being conveyed while being turned in a spiral shape using a skew turning roll 5. As shown in FIG. Antioxidant 005-5 in the outermost layer
．． On the outer surface of the external polyolefin-covered ffm pipe pile, which contains polyolefin 2 containing 0% by weight and whose outer surface has been subjected to corona discharge treatment, urethane primer or modified polyolefin primer 16, fluorine-based paint of various colors, acrylic-silicon-based paint, acrylic - Heavy duty anti-corrosion coated steel pipe pile characterized by laminating a colored paint film 4 such as urethane paint, and as shown in Fig. 2, an antioxidant of 0.05 to 5.0 is applied to the outermost layer of the outer surface of the steel pipe. A steel pipe pile 3 coated with polyolefin on the outer surface having a polyolefin content of % by weight is subjected to a corona discharge treatment using a roll-type electrode 6 that continuously rotates the outer surface while being conveyed while being rotated in a spiral shape with a skew turning roll 5, and then treated with a urethane primer. Alternatively, it is a method for producing heavy corrosion-resistant coated steel pipe piles, which is characterized in that a modified polyolefin primer is applied, and then colored paints such as fluorine-based paints, acrylic-silicon-based paints, acrylic-urethane-based paints, etc. are applied in various colors. .

Hereinafter, the present invention will be explained in detail.

The steel pipe used in the present invention is a pipe made of alloy steel such as carbon steel and stainless steel. In addition, in order to improve the corrosion resistance of steel pipe piles, the outer and inner surfaces of steel pipes are plated with zinc, aluminum, nickel, etc., zinc-iron, zinc-aluminum, etc.
It is also possible to use alloy plating such as zinc-nickel-cobalt, or dispersion plating in which fine inorganic particles such as silica or titanium oxide are dispersed in the plating or alloy plating.

For steel pipe piles coated with external polyolefin, the external surface of the steel pipe is blasted using grid blasting, sandblasting, etc. to remove rust, and then the base is treated with a chromate treatment agent and epoxy primer, and then the polyolefin is modified with maleic anhydride, etc. Although it is possible to use a polyolefin-coated steel pipe pile whose outer surface is coated with a polyolefin after being coated with a modified polyolefin adhesive, from the point of view of the present invention, it is sufficient that the outermost layer of the coated steel pipe pile has a polyolefin, and conventional ground preparation is required. It is possible to use a steel pipe pile coated with polyolefin on the outside, which has been subjected to a known chromate treatment agent, epoxy brimer phosphate treatment, silane coupling agent, etc. alone, or a combination of these surface treatments.

The polyolefin coated on the outermost layer of the external polyolefin-coated steel pipe pile includes low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene containing an antioxidant in the range of 0.05 to 5.0% by weight. Polyolefins such as polyethylene, polypropylene, and polyolefin copolymers such as ethylene-propylene block or random copolymers, polyamide-propylene block or random copolymers, etc. can be used. Antioxidant content of polyolefin coating is 0.05% by weight
If the amount is less than 5.0% by weight or more than 5.0% by weight, the polyolefin coating and various colored fluorine-based, acrylic-based
The adhesion between the silicone-based or acrylic-urethane paint film decreases, and blisters occur in the paint film.

Next, the corona discharge treatment applied to the polyolefin-coated outer surface of the outer polyolefin-coated steel pipe pile will be described. For corona discharge treatment, colored paints of various colors can be applied to the surface of the polyolefin coating after discharge treatment without repelling and cured to form a coating film, and the key is to apply discharge treatment uniformly to the outer surface of the polyolefin coating. is necessary. For this purpose, a method using a roll-type electrode coated with a silicone resin that rotates continuously can be used. If the outer surface of the polyolefin coating is not uniformly treated with corona discharge, the adhesion between the polyolefin coating and the colored paint coating of various colors will decrease after the marine practical test, and blisters will occur in the paint coating. Regarding the degree of corona treatment, for example, in the case of low-density polyethylene, high-density polyethylene, and ethylene-propylene block copolymer coatings, corona discharge is performed using the "Wetting test method for polyethylene and polypropylene films" specified in JIS K6768. "Wetting index (surface tension)" after treatment is 36 dyn/
It is desirable to carry out the discharge treatment so that the thickness becomes at least cm.

If the "wetting index (surface tension)" is less than 36 dyn/cm, the adhesion between the polyolefin coating and the colored paint film of various colors will decrease after the marine practical use test, and the colored paint film will deteriorate. Blisters occur.

Next, the urethane primer and modified polyolefin primer to be applied to the surface of the corona discharge-treated polyolefin-coated steel pipe pile will be explained. The urethane primer used in the present invention has a molecular weight of 400 from the viewpoint of water resistance.
A urethane prepolymer containing a terminal isocyanate group obtained by reacting a polyol compound having a molecular weight of 2000 to 2,000 and having two or more hydroxyl groups in the molecule with a polyisocyanate compound having an incyanate group in the molecule is desirable. In addition, from the viewpoint of water resistance, the modified polyolefin primer is preferably a liquid primer in which a modified polyolefin whose main component is a polyolefin modified with an acid anhydride such as ethylene-vinyl acetate copolymer or maleic anhydride is diluted with a solvent. As general commercially available products, "Thermotac": 200J, "Thermotac E300", "Thermotac E500J", etc. manufactured by Chugoku Paint Co., Ltd. can be used.

Next, the colored paint to be laminated on the outer surface of the corona discharge-treated outer polyolefin-coated steel pipe pile will be described. From the viewpoint of weather resistance, the paints include NY Bolin K in various colors manufactured by Shinto Paint Co., Ltd., and Top # in various colors manufactured by Dainippon Toyo Co., Ltd.
General commercially available acrylic-urethane paints such as 100, Silica Lac in various colors manufactured by Chugoku Paint Co., Ltd., general commercially available acrylic-silicon paints such as Ceraforte in various colors manufactured by Shinto Paint Co., Ltd., and Nippon Paint Co., Ltd. Duflon in various colors,
It is desirable to use commercially available fluorine-based paints such as Sinto Flon in various colors manufactured by Shinto Yoyo Co., Ltd. and V-Flon manufactured by Dainippon Toyo Co., Ltd.

Next, a method of manufacturing a heavily anti-corrosion coated steel pipe pile according to the present invention will be explained.

As shown in Figure 's2, a steel pipe pile coated with polyolefin on its outer surface, which has a polyolefin 2 containing 0.05 to 5.0% by weight of an antioxidant on the outermost layer of the steel pipe's outer surface, is conveyed while being turned in a spiral shape by a skinny turning roll 5. After the outer surface is subjected to corona discharge treatment with a continuously rotating roll electrode 6, or after the corona discharge,
A tan primer or a modified polyolefin is applied, and then colored paints such as fluorine paints, acrylic-silicon paints, acrylic-urethane paints, etc. of various colors are applied to obtain heavy corrosion-resistant coated steel pipe piles according to the present invention. Regarding the degree of corona discharge treatment of the polyolefin-coated surface, for example, in the case of low-density polyethylene, high-density polyethylene, or ethylene-propylene block copolymer coating, the "wetting test method for polyethylene and polypropylene films" specified in JIS 6768 is used. The "wetting index" (
Discharge treatment is performed so that the surface tension (J) becomes 36 dyn/cm or more. In Fig. 2, two roll-type electrodes 6 coated with silicone resin that are driven and rotated are arranged in a staggered manner.
If it is difficult to achieve uniform corona discharge treatment due to the conveyance pitch of the steel pipe pile, three or more roll-type II poles 6 may be arranged in a staggered manner so that the wetting index (surface tension) j is 36 dyn/
Make sure it is at least cm and uniform. The roll-type electrode 6 that is driven and rotated is effective in making the corona emission 1i uniform.

[Function of the Invention] As shown in FIG. 1 and FIG.
．． External polyolefin-coated steel pipe pile 3 having polyolefin 2 containing 0% by weight and having the outer surface subjected to corona discharge treatment
After applying urethane primer or modified polyolefin primer 16 to the outer surface of or on the outer surface, colored paints such as fluorine-based paints, acrylic-silicon-based paints, acrylic-urethane-based paints, etc. in various colors! ! ! 11!
This is a steel pipe pile with heavy anti-corrosion coating made of 4 layers. Furthermore, the method for manufacturing heavy anticorrosion liquid 'N steel pipe piles of the present invention is as shown in FIG.
An outer surface polyolefin-coated steel pipe pile 3 having a polyolefin containing 0.05 to 5.0% by weight of an antioxidant in the outermost layer of the outer surface of the steel pipe is conveyed while being turned in a spiral shape by skinny turning rolls 5, while the outer surface is continuously conveyed. After the corona discharge N treatment is performed using the rotating roll electrode 6, or after the corona discharge treatment, a urethane primer or modified polyolefin primer 16 is applied, and then various colored fluorine paints, acrylic-silicon paints, acrylic-urethane paints are applied. Manufactured by applying colored paints such as paints.

In addition, in the figure, polyolefin 2 has a film thickness of 1 to 10+pm,
Fluorine paints in various colors, acrylic-silicon paints,
Colored paint coating film 4 such as acrylic-urethane paint is 10~
Good results are obtained with a film thickness of 100μ.

[Example] Example 1 Outer diameter 200A, wall thickness 5.8mm, length 5500mm
While conveying the steel pipe while turning it in a spiral shape on a skew turning roll, the outer surface was subjected to grid blasting to remove rust and a chromate treatment agent was applied to the pipe to achieve a total chromium adhesion amount of 350 mg/m2 as shown in Figure 1. The chromate treatment agent wave 11!7 is coated by coating and baking to cover the chromate treatment agent wave 11!7, and the epoxy primer is spray-coated to a film thickness of 50μ and cured by heating to coat the epoxy primer coating 8. A maleic anhydride-modified linear low-density polyethylene adhesive was electrostatically coated to a film thickness of 200μ, heated and melted, and a molten black low-density polyethylene sheet was extruded from a T-die onto the surface and wound in a spiral shape. The outer surface of the pile was coated with low-density polyethylene to obtain a steel pipe pile coated with low-density polyethylene. The content of antioxidant in the low density polyethylene coating 2 was 0.3% by weight, and the film thickness of the low density polyethylene coating was 2.5 mm. As shown in FIG. 2, the Nwi pipe pile with the outer surface covered with low-density polyethylene obtained as described above was conveyed while being turned in a spiral shape (circumferential speed: 2.75 m/+nin) by a skew turning roll 5. Rotate the outer surface electrically (peripheral speed: 2.75m/wi
n) roll-type electrode 6 (silicon resin coating thickness:
After corona discharge treatment with 10 mm), fluorine-based paint (
Duflon manufactured by Nippon Paint Co., Ltd., Marcel value of color tone:
IOB 5/10 (blue)) was spray-painted to a film thickness of 30 μm to cover the colored paint film 4, thereby obtaining a heavily anti-corrosion coated steel pipe pile (2) according to the present invention. "Wetting index (surface tension)" of low-density polyethylene coated surface after corona discharge treatment
was 55 dyn/cm.

As a comparison material, the outer surface of the outer surface low-density polyethylene-coated steel pipe pile obtained as described above was heated with a propane burner for 5 minutes to raise the temperature of the surface to 70 to 80°C, and then a urethane primer (urethane polymer 50% by weight) was applied to the surface. %, toluene 50% by weight), and then apply 5 to 10μ of fluororesin paint (60% by weight of fluororesin, 26% by weight of pigment, 14% by weight of isocyanate, Marcel value of color tone: IOB 5).
/10) was applied to obtain a steel pipe pile with comparatively heavy corrosion protection coating.

Heavy-duty anti-corrosion coated steel pipe pile according to the present invention obtained as described above■
A heavy-duty anti-corrosion coated steel pipe pile■ was subjected to a three-year actual marine use test, and after the test was completed, the presence or absence of blisters on the fluorine-based paint film or fluororesin paint film was observed, and the presence or absence of blisters on these colored paint films. and low density polyethylene coating [base test: according to JIS 5400,
The adhesive strength was evaluated on a scale of 0 to 10 (out of 10). The test results are shown in Table 1.

As is clear from the results in Table 1, the heavy corrosion-resistant coated steel pipe pile according to the present invention has a 3.
Even after a year of marine practical use tests, there was no blistering of the fluorine-based paint film, and the adhesion between the fluorine-based paint film and the low-density polyethylene coating was sufficiently high, and the bond between the colored paint film and the heavy anti-corrosion coating was extremely high. The water-resistant adhesion of this product is significantly superior.

Example 2 The content of antioxidant in the low density polyethylene coating of the external low density polyethylene coated steel pipe pile used for manufacturing the heavy corrosion protection coated steel pipe pile of the present invention in Example 1 was set in the range of 0.05 to 5% by weight. However, heavy corrosion-resistant coated steel pipe piles (1) to (2) according to the present invention were manufactured in the same manner as in Example 1. As a comparative example, Example 1
In the same manner as above, the content of the antioxidant is 0.01% by weight.
Comparative heavy-duty corrosion-resistant steel pipe piles (2) and comparative heavy-duty corrosion-resistant steel pipe piles (2) in which the content of the antioxidant was 6% by weight were manufactured. Comparison of the heavy-duty anti-corrosion coated steel pipe piles obtained as described above The heavy-duty anti-corrosion coated steel pipe piles were subjected to the same 3-year marine service test as in Example 1, and after the test, fluorine-based paint coating or fluororesin paint coating was applied. In addition to observing the presence or absence of blisters, we conducted an adhesion test between these colored coatings and the low-density polyethylene coating [
Base test: According to JIS K5400, adhesive strength is 0
- Displayed with a rating of 10 (out of 10 points)]. The test results are shown in Table 1.

As is clear from the results in Table 1, if the antioxidant content in the polyolefin coating of the heavy corrosion protection coated steel pipe pile according to the present invention is in the range of 0.05 to 5% by weight, it will last for three years in the marine environment. Even after the use test, there was no blistering of the fluorine-based paint film, and the adhesion between the fluorine-based paint film and the low-density polyethylene coating was sufficiently high. However, the antioxidant content was 0.01% by weight. and 6% by weight, blisters occur in the fluorine-based paint film and the adhesion between the fluorine-based paint film and the low-density polyethylene coating also decreases.

Example 3 In the same manner as in Example 1, the degree of corona discharge treatment applied to the outer low-density polyethylene coating was determined by "wetting index (surface tension)".
heavy corrosion-resistant coated steel pipe piles (1) to (2) according to the present invention were manufactured by changing the corrosion resistance to 36 to 70 dyn/cm (in terms of 36 to 70 dyn/cm). As a comparative example, a comparative heavy anti-corrosion coated steel pipe pile (2) was manufactured in the same manner as in Example 1, in which the degree of corona discharge treatment was 34 dyn/cm in terms of "wetting index (surface tension)". Comparison of the heavy-duty anti-corrosion coated steel pipe piles obtained as described above was subjected to the same 3-year ocean service test as in Example 1, and after the test was completed,
In addition to observing the presence or absence of blisters on the fluorine-based paint film or fluororesin paint film, an adhesion test between these colored paint films and the low-density polyethylene coating [base test: adhesion strength according to JIS 5400] was conducted. displayed on a scale of 0 to 1o (out of 10)] and then closed. Test results first
Shown in the table.

As is clear from the results in Table 1, when the degree of corona discharge treatment used in the present invention is 36 to 70 dyn/cm in terms of "wetting index (surface tension)", fluorine-containing There is no occurrence of blisters in the paint film, and the adhesion between the fluorine-based paint film and the low-density polyethylene coating is sufficiently high. However, the "wetting index (surface tension)" is 3
At 4 dyn/cm, blisters occur in the fluorine-based paint film, and the adhesive force between the fluorine-based paint film and the low-density polyethylene coating also decreases.

Example 4 Using the same method as in Example 1, the steel pipe pile coated with low density polyethylene on the outside was replaced with a steel pipe pile coated on the outside with high density polyethylene, and the steel pipe pile coated on the outside with ethylene propylene block copolymer to produce a heavy corrosion protection coated steel pipe pile according to the present invention. ■～■ were manufactured. Comparison of the heavy-duty anti-corrosion coated steel pipe piles obtained as described above The heavy-duty anti-corrosion coated steel pipe piles were subjected to the same 3-year marine service test as in Example 1, and after the test, fluorine-based paint coating or fluororesin paint coating was applied. In addition to observing the presence or absence of blistering, an adhesion test was conducted between these colored coatings and the low-density polyethylene coating [substrate test: according to JIS K5400, the adhesion strength was expressed on a scale of 0 to 1o (out of 10). I did this. The test results are shown in Table 1.

As is clear from the results in Table 1, the heavy corrosion-resistant coated steel pipe pile according to the present invention can be coated with fluorine-based paint even after three years of marine practical use tests, regardless of the type of polyolefin used in the exterior polyolefin-coated steel pipe pile used for its manufacture. No blistering occurs in the coating film, and the adhesive force between the fluorine-based paint coating and the low-density polyethylene coating is sufficiently high.

Example 5 In the same manner as in Example 1, fluorine-based paint (Duflon manufactured by Nippon Paint Co., Ltd., Marcel value of color tone: 1085/10)
(Blue color)) was replaced with the acrylic-silicon and acrylic-urethane colored paints shown in Table 3 to produce heavy anti-corrosion coated steel pipe piles 1 to 0 according to the present invention. Comparison of the heavy-duty anti-corrosion coated steel pipe piles obtained as described above The heavy-duty anti-corrosion coated steel pipe piles were subjected to a three-year marine practical test in the same manner as in Example 1. In addition to observing the presence or absence of blisters, an adhesion test was conducted between these colored coatings and a low-density polyethylene coating [substrate test:
Adhesive strength was evaluated according to JISK 5400 with a rating of 0 to 1o (out of 10). The test results are shown in Table 1.

As is clear from the results in Table 1, even when acrylic-silicon-based or acrylic-urethane-based colored paints were used, there was no occurrence of blisters in the colored paint film even after three years of actual marine usage tests. Moreover, the adhesion between the fluorine-based paint film and the low-density polyethylene coating is sufficiently high.

Example 6 A steel pipe with an outer diameter of 200A, a wall thickness of 5.8mm, and a length of 5500mm was conveyed while being turned in a spiral on a skinny turning roll, and the outer surface was subjected to grid blasting to remove rust. As shown, apply the chromate treatment agent so that the total amount of chromium deposited is 350 mg/m'' and bake it to cover the chromate treatment agent film 7, then spray paint the epoxy primer to a film thickness of 50μ and heat. It is cured and coated with the epoxy primer coating 8, and then a powdered maleic anhydride-modified linear low-density polyethylene adhesive is electrostatically applied to a film thickness of 200 μm and heated and melted to form a modified polyolefin adhesive. 9 coated,
The surface was coated with a molten black density polyethylene sheet extruded from a T-die and wound spirally to obtain a steel pipe pile with an outer surface coated with low density polyethylene. The content of antioxidant in the low density polyethylene coating 2 is 0.3% by weight,
The film thickness of the low density polyethylene coating was 2.5 mm.

The outer surface of the steel pipe pile coated with low-density polyethylene obtained as described above was turned in a spiral shape with a skin tanning roll 5 (peripheral speed: 2.75 m/m), as shown in Fig. 2.
A roll-type electrode 6 whose outer surface is electrically rotated (circumferential speed: 2.75 m/m1n) while being conveyed while
After corona discharge treatment with (silicone resin coating thickness: 10 mm), fluorine paint (Duflon manufactured by Nippon Paint Co., Ltd., Marcel value of color tone: IOB S/10 (blue)
) was spray-painted to a film thickness of 30 μm to obtain a heavy anti-corrosion coated steel pipe pile [phase] according to the present invention. The "wetting index (surface tension)" of the low density polyethylene coated surface after the corona discharge treatment was 55 dyn/cm.

As a comparison material, the outer surface of the outer surface low-density polyethylene-coated steel pipe pile obtained as described above was heated with a propane burner for 5 minutes to raise the temperature of the surface to 70 to 80°C, and then a urethane primer (urethane polymer 50% by weight) was applied to the surface. %, toluene 50% by weight), and then apply 5 to 10μ of fluororesin paint (60% by weight of fluororesin, 26% by weight of pigment, 14% by weight of isocyanate, Marcel value of color tone: IOB 5).
/10) was coated with 30 μm of paint to obtain a comparatively heavy anti-corrosion coated steel pipe pile (■).

Heavy anti-corrosion coated steel pipe pile according to the present invention obtained as described above @
A heavy-duty anti-corrosion coated steel pipe pile■ was subjected to a three-year actual marine use test, and after the test was completed, the presence or absence of blisters on the fluorine-based paint film or fluororesin paint film was observed, and the presence or absence of blisters on these colored paint films. An adhesion test between the sample and the low-density polyethylene coating [substrate test: according to JIS K5400, adhesion strength is expressed on a scale of 0 to 10 (out of 10 points)] was conducted. The test results are shown in Table 2.

As is clear from the results in Table 2, the heavy corrosion-resistant coated steel pipe pile according to the present invention has a 3.
Even after a year of marine practical use tests, there was no blistering of the fluorine-based paint film, and the adhesion between the fluorine-based paint film and the low-density polyethylene coating was sufficiently high, and the bond between the colored paint film and the heavy anti-corrosion coating was extremely high. The water-resistant adhesion of this product is significantly superior.

Example 7 The content of antioxidant in the low-density polyethylene coating of the external low-density polyethylene-coated steel pipe pile used for manufacturing the heavy corrosion-resistant coated steel pipe pile of the present invention in Example 6 was set in the range of 0.05 to 5% by weight. Instead, a heavy anti-corrosion coated steel pipe pile [phase] ~0 according to the present invention was manufactured using the same method as in Example 6. As a comparative example, a comparative heavy-duty anti-corrosion coated steel pipe pile (■) in which the content of the antioxidant is 0.01% by weight and a comparative heavy-duty coated steel pipe pile (2) in which the content of the antioxidant is 6% by weight were prepared in the same manner as in Example 6. Anti-corrosion coated steel pipe pile ■ was manufactured. Comparison of the heavy-duty anti-corrosion coated steel pipe piles obtained as above The heavy-duty anti-corrosion coated steel pipe piles were subjected to the same 3-year marine service test as in Example 6, and after the test, the fluorine-based paint coating or fluororesin paint coating was In addition to observing the presence or absence of blisters, an adhesion test was conducted between these colored coatings and the low-density polyethylene coating [substrate test: according to JIS 5400,
Adhesive strength was expressed on a scale of 0 to 10 (out of 10). The test results are shown in Table 2.

As is clear from the results in Table 's2, if the antioxidant content in the polyolefin coating of the heavy-duty anti-corrosion coated steel pipe pile according to the present invention is in the range of 0.05 to 5% by weight, the marine life will last for three years. Even after the use test, no blistering occurred in the fluorine-based paint film, and the adhesion between the fluorine-based paint film and the low-density polyethylene coating was sufficiently high. However, when the antioxidant content is 0.01% by weight and 6% by weight, blisters occur in the fluorine-based paint film, and the fluorine-based paint film and low-density polyethylene coating The adhesive strength between them also decreases.

Example 8 In the same manner as in Example 6, the degree of corona discharge treatment applied to the outer low-density polyethylene coating was determined by "wetting index (surface tension)".
heavy corrosion-proof coated steel pipe piles O to 0 according to the present invention were manufactured by changing the corrosion resistance to 36 to 70 dyn/cm in terms of 36 to 70 dyn/cm. As a comparative example, a comparative heavy anti-corrosion coated steel pipe pile (2) was manufactured using the same method as in Example 6, in which the degree of corona discharge treatment was 34 dyn/cm in terms of "wetting index (surface tension)". Comparison of the heavy-duty anti-corrosion coated steel pipe piles obtained as above and the heavy-duty anti-corrosion coated steel pipe piles were subjected to the same 3-year ocean service test as in Example 6, and after the test was completed,
In addition to observing the presence or absence of blisters on the fluorine-based paint film or the fluororesin paint film, an adhesion test was conducted between these colored paint films and the low-density polyethylene coating [substrate test: according to JIS K5400, the adhesion strength was measured. The display was performed using a rating scale of 0 to 10 (out of 10 points). The test results are shown in Table 2.

'As is clear from the results in the $2 table, the corona radiation used in the present invention! When the degree of treatment is 36 to 70 dyn/cm in terms of "wetting index (surface tension)", there is no blistering of the fluorine-based paint film even after three years of actual marine use tests, and it has a low density compared to the fluorine-based paint film. The adhesive strength between the polyethylene coating and the polyethylene coating is also sufficiently high. However, when the "wetting index (surface tension)" is 34 dyn/cm, blisters occur in the fluorine-based paint film, and the adhesive force between the fluorine-based paint film and the low-density polyethylene coating also decreases.

Example 9 Using the same method as in Example 6, the steel pipe pile coated with low-density polyethylene on the outside was replaced with a steel pipe pile coated with high-density polyethylene on the outside, and a steel pipe pile coated with ethylene-propylene block copolymer on the outside to produce a heavy-duty anti-corrosion coated steel pipe according to the present invention. Piles [phases] ~■ were manufactured. Comparison of the heavy-duty anti-corrosion coated steel pipe piles obtained as above The heavy-duty anti-corrosion coated steel pipe piles were subjected to the same 3-year marine service test as in Example 6, and after the test, the fluorine-based paint coating or fluororesin paint coating was In addition to observing the presence or absence of blisters, an adhesion test was conducted between these colored coatings and the low-density polyethylene coating [base test: according to JIS K5400, the adhesion strength was expressed on a scale of 0 to 10 (out of 10). I did this. The test results are shown in Table 2.

As is clear from the results in Table 2, the heavy corrosion-resistant coated steel pipe pile according to the present invention can be coated with fluorine-based paint even after three years of actual marine use tests, regardless of the order of the polyolefin in the external polyolefin-coated steel pipe pile used for its manufacture. No blistering occurs in the coating film, and the adhesive force between the fluorine-based paint coating and the low-density polyethylene coating is sufficiently high.

Example 10 A fluorine-based paint (Duflon manufactured by Nippon Paint Co., Ltd., Marcel value of color tone: IOB 5/1) was applied in the same manner as in Example 6.
0 (blue)) was replaced with the acrylic-silicon-based and acrylic-urethane-based coloring paints shown in Table 3, heavy anti-corrosion coated steel pipe piles O-O according to the present invention were manufactured. Comparison of the heavy-duty anti-corrosion coated steel pipe piles obtained as above The heavy-duty anti-corrosion coated steel pipe piles were subjected to the same 3-year marine service test as in Example 6, and after the test, the fluorine-based paint coating or fluororesin paint coating was In addition to observing the presence or absence of blistering, an adhesion test was conducted between these colored coatings and a low-density polyethylene coating [substrate test: according to JIS K5400, the adhesion was graded from o to 1o (i.

(full score)] was carried out. The test results are shown in Table 2.

As is clear from the results in Table 2, even when acrylic-silicon-based or acrylic-urethane-based colored paints were used, there was no occurrence of blisters in the colored paint film even after three years of actual marine usage tests. Moreover, the adhesion between the fluorine-based paint film and the low-density polyethylene coating is sufficiently high.

Example 11 The present invention was carried out in the same manner as in Example 6, except that the modified polyolefin primer (Thermotac E300J manufactured by China Paint Co., Ltd.) was replaced with a urethane primer (50% by weight of urethane prepolymer containing terminal isocyanate groups, 50% by weight of toluene). A heavily anti-corrosion coated steel pipe pile 0 was manufactured.The heavy anti-corrosion coated steel pipe pile O obtained as described above was subjected to the same 3-year marine practical test as in Example 6, and after the test, no blisters were generated from the colored paint coating. In addition to observing the presence or absence of the coating, the adhesion test between these colored coatings and the low-density polyethylene coating was conducted [substrate test: according to JISK5400, the adhesion strength was evaluated on a scale of 0 to 10 (out of 10). The test results are shown in Table 2.

As is clear from the results in Table 2, even when a urethane primer was used instead of a modified polyolefin primer, there was no blistering of the colored paint film even after three years of actual marine use tests, and the coloring paint coating remained stable. The adhesion between the membrane and the low density polyethylene coating is also sufficiently high.

Table 3 (Effects of the invention) As is clear from the above examples, the outermost layer of the steel pipe contains a polyolefin containing 0.05 to 5.0% by weight of an antioxidant and whose surface has been subjected to corona discharge treatment. Apply urethane primer or modified polyolefin primer to the outer surface of the external polyolefin-coated steel pipe pile or to the outer surface, and then apply colored paints such as fluorine-based paints, acrylic-silicon-based paints, acrylic-urethane-based paints, etc. in various colors. The heavy-duty anti-corrosion coated steel pipe pile of the present invention, which is obtained by the above-mentioned method, is different from conventional heavy-duty anti-corrosion coated steel pipe piles in that it is coated with colored paints such as fluorine-based paints, acrylic-silicon paints, and acrylic-urethane-based paints in various colors. The water-resistant adhesion between the material and the polyolefin coating is significantly superior.

[Brief explanation of drawings]

Figures 1 and 4 are partial cross-sectional views of heavy-duty corrosion-resistant coated steel pipe piles according to the present invention, Figure 2 is a diagram showing an example of the manufacturing method of heavy-duty corrosion-proof coated steel pipe piles according to the present invention, and Figure 3 is a diagram showing a conventional heavy-duty coated steel pipe pile. FIG. 3 is a diagram showing a partial cross section of the anti-corrosion coated steel material. In the figure, 1 is a steel pipe or steel material, 2 is an antioxidant at 0.05
3 is a polyolefin-covered Nm pipe pile whose outermost layer on the outer surface of the steel pipe is coated with a polyolefin containing 0.05 to 5.0% by weight of an antioxidant. , 4 is a colored paint film of various colors such as fluorine paint, acrylic-silicon paint, acrylic-urethane paint, etc., 5 is a skew turning roll, 6 is a continuously rotating roll electrode, and 7 is a chromate treatment agent. Coating film, 8 is epoxy brimer coating, 9 is modified polyolefin adhesive, 10 is inorganic brimer 1
1 is an organic primer; 12 is an adhesive layer; 13 is a polyolefin resin layer; 14 is a urethane primer layer; 15 is a fluororesin layer containing a colored pigment; and 16 is a urethane primer or modified polyolefin primer layer. 1: Steel pipe 2: Polyolefin containing 0.05 to 5.0% by weight of antioxidant and having the outer surface treated with corona discharge 4: Fluorine paint in various colors, acrylic-silicon paint, acrylic-urethane paint, etc. Colored paint coating 7: Chromate treatment agent coating 8: Epoxy primer coating 9: Modified polyolefin adhesive 0: Inorganic brimer 1: Organic brimer 2: Adhesive layer 3: Polyolefin resin layer 4: Urethane primer layer 5: Fluororesin layer 6 containing colored pigment: urethane primer or modified polyolefin primer

Claims (1)

[Claims] 1. An antioxidant of 0.05 to 5.0 is added to the outermost layer of the outer surface of the steel pipe.
% by weight and whose outer surface has been treated with corona discharge treatment.The outer surface of the steel pipe pile coated with polyolefin is coated with colored paint films such as fluorine-based paints, acrylic-silicon-based paints, and acrylic-urethane-based paints in various colors. A heavy-duty anti-corrosion coated steel pipe pile characterized by its laminated structure. 2 Add 0.05 to 5.0 of antioxidant to the outermost layer of the outer surface of the steel pipe.
A steel pipe pile coated with polyolefin on the outside having a polyolefin content of % by weight is subjected to a corona discharge treatment using a roll-type electrode that continuously rotates the outer surface while being conveyed while being turned in a spiral shape with a skew turning roll. A method for manufacturing a steel pipe pile with heavy anti-corrosion coating, characterized by coating with a colored paint such as paint, acrylic-silicon paint, acrylic-urethane paint, etc. 3 Add 0.05 to 5.0 of antioxidant to the outermost layer of the outer surface of the steel pipe.
% by weight and whose outer surface is corona discharge treated with polyolefin.On the outer surface of the steel pipe pile coated with polyolefin, urethane primer or modified polyolefin primer, fluorine-based paints of various colors, acrylic-silicon-based paints, acrylic-urethane-based paints are applied. Heavy-duty anti-corrosion coated steel pipe piles characterized by laminated colored paint films such as. 4 Add 0.05 to 5.0 of antioxidant to the outermost layer of the outer surface of the steel pipe.
A steel pipe pile coated with polyolefin on the outer surface having a polyolefin content of % by weight is subjected to a corona discharge treatment using a roll-type electrode that continuously rotates the outer surface while being conveyed while being turned spirally with a skew turning roll, and then the outer surface is coated with urethane. 1. A method for manufacturing heavy corrosion-resistant coated steel pipe piles, which comprises applying a primer or a modified polyolefin primer, and then applying colored paints such as fluorine paints, acrylic-silicon paints, and acrylic-urethane paints in various colors.