KR20160115893A - Coating powder for coating steel pipe, coated steel pipe, and method for coating steel pipe - Google Patents

Abstract

Provided are powder paint for coating steel pipes, coated steel pipe, and steel pipe coating method. The powder paint for coating steel pipes includes a modified polyethylene resin, a polystyrene-based resin, and an adhesive resin. The coated steel pipe includes a steel pipe and a coated film which is provided on a surface of the steel pipe and is formed by the powder paint for coating the steel pipe. The steel pipe coating method includes the following steps: treating a surface of the steel pipe; supplying the powder paint for coating steel pipe onto the surface of the steel pipe so as to form the coating film; and curing the coating film.

Description

TECHNICAL FIELD [0001] The present invention relates to a powder coating material for a steel pipe coating, a coated steel pipe and a steel pipe coating method,

The present invention relates to a powder coating material for steel pipe coating, a steel pipe coated with the powder coating material for steel pipe coating, and a method for coating steel pipe using the powder coating material for steel pipe coating.

Steel pipes are widely used in various buildings, structures, and industrial facilities. Especially, steel pipes are widely used as pipelines such as gas and oil. The steel pipe is used because it is in contact with water or the atmosphere and is likely to be damaged in an environment such as rust or cold. Conventionally, a paint containing an organic solvent is used to paint a steel pipe or a film is adhered to the surface of a steel pipe to form a paint film. However, the organic solvent is not only harmful to the human body and the environment but also has recently been restricted in its use due to deepening of environmental regulations. The coating film of the film is complicated and the coating film is formed properly . Recently, there has been proposed a powder coating material for coating the surface of a steel pipe, but the adhesion strength to the surface of the steel pipe, the surface hardness, and the abrasion resistance are weak, and there is a problem that the steel is easily peeled or broken from the steel pipe.

In order to solve the above-mentioned problems, the present invention provides a powder coating material for coating a steel pipe, which is coated on the surface of a steel pipe to protect the steel pipe.

The present invention provides a powder coating material for steel pipe coating having excellent physical properties.

The present invention provides a powder coating material for steel pipe coating excellent in adhesion strength to a steel pipe.

The present invention provides a powder coating material for steel pipe coating excellent in surface hardness.

The present invention provides a powder coating material for steel pipe coating excellent in abrasion resistance.

The present invention provides a coated steel pipe coated with the powder coating for steel pipe coating.

The present invention provides a steel pipe coating method using the powder coating material for steel pipe coating.

The present invention provides a simple steel pipe coating method.

Other objects of the present invention will become apparent from the following detailed description and the accompanying drawings.

The powder coating for steel pipe coating according to the embodiments of the present invention includes a modified polyethylene resin, a polystyrene resin, and an adhesive resin. The melt flow index (190 DEG C, 2.16 kg) of the powder coating for steel pipe coating may be 3 to 40 g / 10 min.

The modified polyethylene resin may be formed by grafting maleic anhydride onto at least one selected from polyethylene, high density polyethylene, low density polyethylene, and linear low density polyethylene.

The polystyrene-based resin may include at least one selected from general-purpose polystyrene, high-impact polystyrene, and polystyrene copolymer, and the polystyrene copolymer may be at least one selected from the group consisting of styrene-butadiene copolymer, acrylonitrile-butadiene- Styrene copolymer, styrene-butadiene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer, and styrene-ethylene-butadiene-styrene copolymer.

The adhesive resin is selected from the group consisting of a polyolefin rubber, a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a high density polyethylene (HDPE), an ethylene vinyl acetate (EVA), a polypropylene (PP), and a butadiene rubber And the polyolefin-based rubber may include at least one selected from the group consisting of an ethylene octene copolymer, an ethylene butene copolymer, an ethylene propylene copolymer, an ethylene propylene diene monomer rubber, and an ethylene propylene monomer rubber.

The modified polyethylene resin may be contained in an amount of 10 to 50 parts by weight, the polystyrene-based resin may be 5 to 30 parts by weight, and the adhesive resin may be contained in an amount of 30 to 60 parts by weight based on 100 parts by weight of the powder coating material.

A coated steel pipe according to embodiments of the present invention includes a steel pipe and a coating film provided on the surface of the steel pipe, and the coating film is formed by the steel pipe coating powder coating.

The coated steel pipe may further include a primer film provided between the steel pipe and the coating film, and the primer film may be formed of an epoxy resin.

The method for coating a steel pipe according to embodiments of the present invention includes the steps of treating the surface of a steel pipe, forming a coating film by providing the steel pipe coating powder coating on the surface of the steel pipe, and curing the coating film do.

The surface treatment step may include a heating step and a sanding treatment step.

In the coating film forming step, the steel pipe may be induction-heated.

The coating film may be formed by a fluid immersion coating or an electrostatic coating. The coating film forming step may include forming a primer film by providing an epoxy resin powder on the surface of the steel pipe before providing the powder coating material for steel pipe coating.

The powder coating material for steel pipe coating according to the embodiments of the present invention is excellent in properties such as adhesion strength, surface hardness, abrasion resistance, impact resistance, flexural resistance, coating property, water resistance, flexibility and cold resistance. Particularly, the powder coating material for steel pipe coating has excellent adhesion strength to the surface of the steel pipe and can be bonded to the steel pipe for a long time to protect the steel pipe. The above-mentioned powder coating for steel pipe coating has an excellent surface hardness and can have an improved strength. The powder coating material for steel pipe coating may have excellent abrasion resistance. The coated steel pipe coated with the powder coating for steel pipe coating can be used for a long time without being damaged in various environmental conditions. The surface of the steel pipe can be coated by a simple process using the powder coating material for steel pipe coating.

1 shows a coated steel pipe according to an embodiment of the present invention.
2 shows a coated steel pipe according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to examples. The objects, features and advantages of the present invention will be easily understood by the following embodiments. The present invention is not limited to the embodiments described herein, but may be embodied in other forms. The embodiments disclosed herein are provided so that the disclosure may be thorough and complete, and that those skilled in the art will be able to convey the spirit of the invention to those skilled in the art. Therefore, the present invention should not be limited by the following examples.

The sizes of the elements in the figures, or the relative sizes between the elements, may be exaggerated somewhat for a clearer understanding of the present invention. In addition, the shape of the elements shown in the drawings may be somewhat modified by variations in the manufacturing process or the like. Accordingly, the embodiments disclosed herein should not be construed as limited to the shapes shown in the drawings unless specifically stated, and should be understood to include some modifications.

[Powder coating for steel pipe coating]

The powder coating for steel pipe coating according to the embodiments of the present invention may include a modified polyethylene resin, a polystyrene resin, and an adhesive resin. The powder coating material may include 10 to 50 parts by weight of the modified polyethylene resin, 5 to 30 parts by weight of the polystyrene resin, and 30 to 60 parts by weight of the adhesive resin.

The melt flow index (190 DEG C, 2.16 kg) of the powder coating material is preferably 3 to 40 g / 10 min. If the melt flow index is less than 3 g / 10 min, the flowability of the powder coating to be melted during coating is too low to form the coating film properly. If the melt flow rate exceeds 40 g / 10 min, the flowability of the powder coating is too high, .

The modified polyethylene resin may be formed by grafting maleic anhydride onto at least one selected from polyethylene, high density polyethylene, low density polyethylene, and linear low density polyethylene. For example, the modified polyethylene may be formed by adding a maleic anhydride (MAH), a peroxide, and an antioxidant to high-density polyethylene, followed by reaction extrusion in a twin-screw extruder at 120 to 200 ° C. The ethylene bonds of the high-density polyethylene are broken by the peroxide to form radicals, and the maleic anhydride is grafted to the high-density polyethylene. The maleic anhydride may be grafted to the high-density polyethylene by the grafting reaction to form a modified polyethylene having a polar group.

The maleic anhydride may be added in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the polyethylene to be modified. If the content of the maleic anhydride is less than 0.1 parts by weight, the grafting rate may be low and the adhesion may be deteriorated. If the content is more than 3 parts by weight, unreacted maleic anhydride may remain.

The peroxide is selected from the group consisting of dicumyl peroxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, p-chlorobenzoyl peroxide, t-butyl peroxyisobutyrate, t-butyl peroxyisopropyl carbonate, 2 Butyl peroxyacetate, di-t-butyl diperoxyphthalate, t-butyl peroxymaleic acid, cyclohexanone peroxide, t-butyl At least one selected from the group consisting of peroxybenzoate, peroxybenzoate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t- butylcumylperoxide, t- butylhydroperoxide and di- . ≪ / RTI >

The antioxidant may include, for example, alkyl phenols, alkylene bisphenols, alkyl phenol thioethers, aromatic amines, and the like.

If the amount of the modified polyethylene is less than 10 parts by weight based on 100 parts by weight of the powder coating, the adhesive strength may be lowered or the durability of the coating film may be lowered. If the content of the modified polyethylene is more than 50 parts by weight, have.

The polystyrene-based resin may include general-purpose polystyrene (GPPS), high-impact polystyrene (HIPS), polystyrene copolymer, and the like. The polystyrene copolymer may be, for example, a styrene-butadiene copolymer (SBR), an acrylonitrile-butadiene-styrene copolymer (ABS), a styrene-butadiene-styrene copolymer (SBS), a styrene- (SEBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), and the like.

By including the polystyrene-based resin, the powder coating material has a higher surface hardness and can have a further improved strength.

If the content of the polystyrene-based resin is less than 5 parts by weight based on 100 parts by weight of the powder coating, the effect of surface hardness may be insignificant. If the content is more than 30 parts by weight, the physical properties of the powder coating may be deteriorated.

The adhesive resin may be one selected from the group consisting of a polyolefin rubber, a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a high density polyethylene (HDPE), ethylene vinyl acetate (EVA), a polypropylene (PP), and a butadiene rubber Or more. The polyolefin-based rubber may include an ethylene octene copolymer, an ethylene butene copolymer, an ethylene propylene copolymer, an ethylene propylene diene monomer rubber, an ethylene propylene monomer rubber and the like.

If the amount of the adhesive resin is less than 30 parts by weight based on 100 parts by weight of the powder coating, the adhesive strength may be lowered. If the amount exceeds 60 parts by weight, the physical properties of the powder coating may be deteriorated.

The powder coating material may further include at least one selected from an antioxidant, a heat stabilizer, a pigment, a dispersion stabilizer, a UV stabilizer, and a plasticizer. For example, the powder coating material may contain 0.1 to 3 parts by weight of the antioxidant, 0.1 to 3 parts by weight of the heat stabilizer, 1 to 3 parts by weight of the pigment, 0.5 to 3 parts by weight of the dispersion stabilizer, 0.1 to 1 part by weight of the ultraviolet stabilizer, and 0.1 to 1 part by weight of the plasticizer.

The antioxidant may include, for example, alkyl phenols, alkylene bisphenols, alkyl phenol thioethers, aromatic amines, and the like. The heat stabilizer may include a Cd / Ba / Zn system, a Cd / Ba system, a Ba / Zn system, a Ca / Zn system, a Na / Za system, a Sn system, a Pb system, a Cd system and a Zn system stabilizer. The pigments may include, for example, iron oxide, cadmium, ultramarine blue, cadmium red, chromium yellow, and the like. The dispersion stabilizer may include polyamide wax, polytetrafluoroethylene, polyacrylate, and the like. The powder coating composition may contain various additives. The dispersion stabilizer can prevent aggregation of the additive during storage or painting and improve the smoothness of the coating film. If the content of the dispersion stabilizer is less than 0.5 parts by weight based on 100 parts by weight of the powder coating composition, the smoothness improvement effect of the coating film may be deteriorated. If the content is more than 3 parts by weight, the coated surface may be cloudy or cloudy. The ultraviolet stabilizer may include, for example, benzotriazole, salicylic acid ester, hydroxybenzophenol, acrylonitrile, and the like. The plasticizer may include, for example, dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, trioctyl phosphate, and the like.

The modified polyethylene, the polystyrene-based resin, the adhesive resin, and the additives may be mixed and reactively extruded in a twin-screw extruder to form a resin for a powder coating material in the form of a pellet.

The resin for the powder coating material in the pellet form may be pulverized by mechanical pulverization and / or freezing pulverization to form a powder coating material having a particle size of 250 탆 or less, preferably 150-200 탆.

[Example]

Powder coatings having a particle size of 150 to 200 μm were prepared by the ingredients and contents shown in Table 1 below. Modified polyethylene is formed by grafting maleic anhydride onto high density polyethylene.

ingredient Example 1
(Parts by weight, kg) Example 2
(Parts by weight, kg) Example 3
(Parts by weight, kg) Example 4
(Parts by weight, kg) Modified polyethylene 30 30 20 40 polystyrene 5 5 5 5 Styrene ethylene butadiene styrene copolymer 10 5 15 20 Ethylene butene copolymer 10 15 15 5 Low density polyethylene 10 10 10 5 Linear low density polyethylene 5 5 5 5 High density polyethylene 10 10 10 10 Ethylene vinyl acetate 5 5 5 5 Butadiene rubber 5 5 5 5 Antioxidant 0.2 0.2 0.2 0.2 Heat stabilizer 0.2 0.2 0.2 0.2 Pigment 2 2 2 2 Dispersion stabilizer 1.5 1.5 1.5 1.5 Ultraviolet stabilizer 0.5 0.5 0.5 0.5 Plasticizer 0.5 0.5 0.5 0.5

A coating film was formed on the surface of a steel pipe with the powder coating material in Table 1, and the properties thereof were evaluated. The results are shown in Table 2 below.

division Assessment Methods Example 1 Example 2 Example 3 Example 4 Melt flow index (g / 10 min) ASTM D 1238 30.9 31.1 33.3 29.3 Adhesive strength (kgf / 25mm) KS F 4737 16.1 15.9 14.8 17.5 Surface hardness Shorea 97 95 98 99 Abrasion resistance (mg) ASTM A 934 5.4 6.8 4.7 3.9 Impact resistance JIS K 5600 clear clear clear clear Flexibility JIS K 5600 Good Good Good Good Coating property Visual evaluation Good Good Good Good

Referring to Table 2, it can be seen that as the content of modified polyethylene increases, the melt flow index decreases and the adhesive strength increases. It is also seen that as the content of the polystyrene-based resin increases, the surface hardness increases. As described above, it can be seen that the powder coatings prepared according to the compositions according to Examples 1 to 4 have excellent physical properties such as adhesive strength, surface hardness, abrasion resistance, impact resistance, flexural resistance and coating properties.

[Coated steel pipe]

1 shows a coated steel pipe according to an embodiment of the present invention.

Referring to Fig. 1, the coated steel pipe 10 includes a steel pipe 11 and a coating film 13 formed on the surface thereof. The coating film 13 may be formed using the powder coating material for steel pipe coating according to the embodiments of the present invention. The coating film 13 may have a thickness of 400 to 600 mu m.

Since the powder coating material includes a modified polyethylene resin, a polystyrene-based resin, and an adhesive resin, the coating film 13 formed by the powder coating material can be formed into a single layer with excellent adhesion strength to the surface of the steel pipe, It is possible to have excellent strength. The coating film 13 is excellent in physical properties such as adhesion strength, surface hardness, abrasion resistance, impact resistance, flexural resistance, coating property, water resistance, flexibility and cold resistance so that the coated steel pipe 10 is not damaged in various environmental conditions, .

2 shows a coated steel pipe according to another embodiment of the present invention.

2, the coated steel pipe 10 includes a steel pipe 11, a primer film 12, and a coating film 13. The primer film 12 may be formed of an epoxy resin and the coating film 13 may be formed of a powder coating material for steel pipe coating according to the embodiments of the present invention. The primer film 12 may have a thickness of 200 to 300 mu m, and the coating film 13 may have a thickness of 400 to 600 mu m.

[Coating method of steel pipe]

A method of coating a steel pipe according to an embodiment of the present invention includes the steps of treating a surface of a steel pipe, providing a steel pipe coating powder coating material according to an embodiment of the present invention on the surface of the steel pipe to form a coating film, And then curing.

The surface of the steel pipe is treated. The steel pipe can be heated to remove foreign substances on the surface, and sanding treatment can be performed. The sanding process can help the surface of the steel pipe to be coated well.

A coating film is formed on the surface of the steel pipe. A high frequency heat treatment or the like is used to induce heating of the steel pipe while providing the surface of the steel pipe with the powder coating material for steel pipe coating according to the embodiments of the present invention. The powder coating material is heated on the surface of a steel pipe to form a coating film. The epoxy resin powder may be provided on the surface of the steel pipe to form the primer film before providing the powder coating material. For example, the coating film and / or the primer film may be formed by a fluid immersion coating. Alternatively, the coating film and / or the primer film may be formed by electrostatic coating to provide a high voltage when the powder coating material and / or the epoxy resin powder are provided on the surface of the steel pipe. The powder coating material and / or the epoxy resin powder adheres well to the surface of the steel pipe by the fluidized deposition coating or the electrostatic coating, so that the consumption amount of the powder coating material and / or the epoxy resin powder can be reduced, The film can be formed quickly and smoothly, and the productivity of the coated steel pipe can be improved.

The coating film is cured by heating and drying. Whereby a coated steel pipe coated with the powder coating material is formed. The coated steel pipe may be cleaned with water and then subjected to electrical inspection or the like.

Hereinafter, specific embodiments of the present invention have been described. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

10: Coated steel pipe 11: Steel pipe
12: Primer film 13: Coating film

Claims (15)

1. A powder coating material coated on a steel pipe for protecting the steel pipe,
Modified polyethylene resin;
Polystyrene type resin; And
A powder coating for a steel pipe coating comprising an adhesive resin. The method according to claim 1,
Wherein the melt flow index (190 DEG C, 2.16 kg) of the powder coating for steel pipe coating is 3 to 40 g / 10 minutes. The method according to claim 1,
Wherein the modified polyethylene resin is formed by grafting maleic anhydride onto at least one selected from polyethylene, high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. The method according to claim 1,
Wherein the polystyrene-based resin comprises at least one selected from general-purpose polystyrene, high-impact polystyrene, and polystyrene copolymer. 5. The method of claim 4,
The polystyrene copolymer may be a styrene-butadiene copolymer, an acrylonitrile-butadiene-styrene copolymer, a styrene-butadiene-styrene copolymer, a styrene-ethylene-butylene-styrene copolymer, Based on the weight of the powder coating material. The method according to claim 1,
The adhesive resin is selected from the group consisting of a polyolefin rubber, a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a high density polyethylene (HDPE), an ethylene vinyl acetate (EVA), a polypropylene (PP), and a butadiene rubber And at least one of the powder coating materials for a steel pipe coating. The method according to claim 6,
Wherein the polyolefin rubber comprises at least one selected from the group consisting of ethylene octene copolymer, ethylene butene copolymer, ethylene propylene copolymer, ethylene propylene diene monomer rubber, and ethylene propylene monomer rubber. The method according to claim 1,
Wherein the modified polyethylene resin is contained in an amount of 10 to 50 parts by weight, the polystyrene-based resin is contained in an amount of 5 to 30 parts by weight, and the adhesive resin is contained in an amount of 30 to 60 parts by weight based on 100 parts by weight of the powder coating material Powder coating. Steel pipe; And
And a coating film provided on the surface of the steel pipe,
Wherein the coating film is formed by the powder coating material for steel pipe coating according to any one of claims 1 to 8. 10. The method of claim 9,
Further comprising a primer film provided between the steel pipe and the coating film,
Wherein the primer film is formed of an epoxy resin. Treating the surface of the steel pipe;
Providing a coating film for a steel pipe coating according to any one of claims 1 to 8 on a surface of the steel pipe to form a coating film; And
And curing the coating film. 12. The method of claim 11,
Wherein the surface treatment step includes a heating step and a sanding treatment step. 12. The method of claim 11,
Wherein the steel pipe is induction-heated in the coating film forming step. 12. The method of claim 11,
Wherein the coating film is formed by fluidized deposition coating or electrostatic coating. 12. The method of claim 11,
Wherein the coating film forming step comprises providing an epoxy resin powder on the surface of the steel pipe to form a primer film before providing the powder coating material for steel pipe coating.

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