JP2008231508A - Corrosion resistant steel pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosion resistant steel pipe in which corrosion prevention effect can be obtained at a base edge part. <P>SOLUTION: The corrosion resistant steel pipe includes a steel pipe 1 and an anode metal layer 3 made of a metal having an ionization tendency higher than that of steel, and in which the steel pipe 1 and the anode metal layer 3 are electrically conducted. The corrosion resistant steel pipe is provided with a coating film layer 2 made of a coating material including a conductive polymer and covering the steel pipe 1; and the anode metal layer 3 fitted to the part so as to be a base edge part on the coating film layer 2. The anode metal layer 3 is made of at least one kind of metal foil selected from the group consisting of zinc foil, aluminum foil, magnesium foil and zinc-aluminum alloy foil. The metal foil may be fitted to the surface of the coating film layer 2 via a conductive adhesive layer, or may be fitted to the surface of the coating film layer 2 via a nonconductive adhesive layer formed leaving the part directly in contact with the coating film layer 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a corrosion-resistant steel pipe used for park facilities, play equipment, pillars such as signs, poles, and the like.

  Steel pipes with anticorrosion coating on their surfaces are used for park facilities, playground equipment, signs and other pillars, and poles. However, the steel pipe is susceptible to rainwater and urine from animals such as dogs, especially at the ground, and the corrosion tends to proceed from the ground. Therefore, an anticorrosion material different from the anticorrosion coating is disposed on the ground portion of the steel pipe.

  Conventionally, it is known to use a metal such as zinc, which has a higher ionization tendency than steel, as the anticorrosion material. A metal having a higher ionization tendency than the steel acts as the anticorrosion material by coating the surface of the steel material with a metal foil made of the metal (for example, see Patent Document 1).

  The action as the anticorrosion material is more specifically, even if cracks, pinholes, etc. occur in the metal foil, and even if corrosion factors such as moisture enter from here, the metal foil acts as an anode, Since the steel melts first, the steel is protected. This action is known as a self-sacrificial anticorrosive action.

  In order to use the metal foil such as zinc for the steel pipe used for the column, pole, etc., for example, there are the following methods. First, masking is performed on a portion that becomes the ground portion of the steel pipe, and a primer coating is applied to other portions to form a primer coating layer. Then, the masking is removed, and a metal foil such as zinc, for example, zinc tape is attached to the portion that becomes the ground portion. The steel pipe is usually formed by laminating an intermediate coating layer made of an intermediate coating and an upper coating layer made of a top coating in this order on the undercoat coating layer and the metal foil.

However, in the steel pipe, it is inevitable that a gap is generated between the undercoat coating layer and the metal foil. When the top coating layer and the intermediate coating layer are peeled off, corrosion factors such as moisture are generated from the gap. Invades and the steel pipe just below the gap is corroded.
JP 2005-60803 A JP 2006-117748 A

  An object of the present invention is to provide an anti-corrosion steel pipe that can eliminate such inconvenience and can reliably obtain an anti-corrosion effect at the ground.

  In order to achieve such an object, the present invention includes a steel pipe and an anode metal layer made of a metal having a higher ionization tendency than steel, and the steel pipe and the anode metal layer are electrically connected to each other. The coating film layer which consists of a coating material containing a conductive polymer and coat | covers this steel pipe, and the anode metal layer with which the part used as the ground part on this coating film layer was equipped is characterized by the above-mentioned.

  In this invention, the said coating-film layer consists of a coating material containing a conductive polymer, and is provided with electroconductivity itself. Therefore, the anode metal layer can be electrically connected to the steel pipe through the coating film layer, and a self-sacrificial anticorrosive action can be obtained.

  Further, in the present invention, when a top coat film made of a top coat is formed on a portion excluding a portion that becomes a ground part on the coat layer, the top coat film and the anode metal layer There is a concern that a gap may be formed between them, and a corrosive factor such as moisture may enter from the gap. However, in this case, the corrosion factor that has entered through the gap is blocked by the coating layer made of the paint containing the conductive polymer.

  Therefore, according to the present invention, the anticorrosion effect can be surely obtained at the ground portion of the steel pipe.

  Moreover, in the anticorrosion steel pipe of the present invention, the anode metal layer may be made of one metal foil selected from the group consisting of zinc foil, aluminum foil, magnesium foil, and zinc-aluminum alloy foil. When using zinc foil as the metal foil, for example, one having a thickness of 0.1 to 0.2 mm can be used.

  Moreover, it is preferable that the said metal foil is mounted | worn on the said coating-film layer through the electroconductive adhesive layer. The metal foil can be stuck on the coating layer by the conductive pressure-sensitive adhesive layer and can be electrically connected to the coating layer through the conductive pressure-sensitive adhesive layer.

  As the conductive adhesive, for example, an acrylic, rubber-based, or silicone-based adhesive in which a conductive filler is dispersed can be used (see Patent Document 2).

  Moreover, it is preferable that the said metal foil is mounted | worn on this coating film layer through the nonelectroconductive adhesive layer formed leaving the part which this metal foil contacts the said coating film layer directly. The metal foil can be stuck on the coating layer by the non-conductive pressure-sensitive adhesive layer, and is in direct contact with the coating layer at a portion where the non-conductive pressure-sensitive adhesive layer is not formed. Can take continuity.

  Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory cross-sectional view showing a configuration of a corrosion-resistant steel pipe according to the present embodiment, FIG. 2 is an enlarged view of a main part of the corrosion-resistant steel pipe shown in FIG. 1, and FIG. It is explanatory sectional drawing shown. Moreover, FIG.4 and FIG.5 is explanatory sectional drawing which shows the repair process of the existing anti-corrosion steel pipe.

  The anticorrosion steel pipe 1 of this embodiment shown in FIG. 1 is used for, for example, park facilities, play equipment, pillars such as signs, poles, and the like. The anticorrosion steel pipe 1 includes a first coating layer 2 that covers the entire surface, an anode metal layer 3 that is attached to a portion of the first coating layer 2 that becomes a ground portion, and a first coating layer 2. And a second coating layer 4 covering the anode metal layer 3.

  The first coating layer 2 is formed of a primer coating containing a conductive polymer. The conductive polymer is an organic polymer having a polyconjugated π electron system, and examples thereof include polyaniline, polypyrrole, polythiophene, and the like, and polyaniline is preferable. The structural formula of polyaniline is shown in the following formula (1).

  As the undercoat paint, for example, a composition comprising 55% by mass of denatured alcohol, 10% by mass of butyral resin, 8% by mass of polyaniline, 4% by mass of brown pigment, and the remaining butanol can be used.

  The anode metal layer 3 is a metal foil made of a metal having a higher ionization tendency than steel, and is made of one metal foil selected from the group consisting of zinc foil, aluminum foil, magnesium foil, and zinc-aluminum alloy foil. Can be used.

  As shown in FIG. 2A, the anode metal layer 3 includes a conductive pressure-sensitive adhesive layer 5a on the entire surface of the metal foil 3a facing the first coating layer 2, and the conductive pressure-sensitive adhesive layer 5a is provided with the conductive pressure-sensitive adhesive layer 5a. It may be stuck to the coating-film layer 2 via. Moreover, as shown in FIG.2 (b), the nonelectroconductive adhesive layer formed leaving the part which contacts the coating film layer 2 directly on the surface facing the 1st coating film layer 2 of metal foil 3a. 5b, and may be attached to the coating layer 2 via the non-conductive pressure-sensitive adhesive layer 5b.

  The non-conductive pressure-sensitive adhesive layer 5b can be provided, for example, in an island shape or a stripe shape on the surface of the metal foil 3a facing the first coating layer 2. When the non-conductive pressure-sensitive adhesive layer 5b is provided in a stripe shape, for example, it may be provided at both end edges along the length direction of the metal foil 3a (FIG. 2 (b) shows this mode). A plurality of strips including the edge may be provided.

  In the present embodiment, as the metal foil 3a, for example, a zinc foil having a thickness of 0.1 to 0.2 mm is processed into a tape shape of 20 to 200 mm, and the conductive adhesive layer 5a is formed on the entire surface of one surface. A thing (it abbreviates as a zinc tape hereafter) can be used.

  The second coating layer 4 is one type of resin selected from the group consisting of epoxy resins, urethane resins, and fluorine resins, all of which are made of a top coating made of a resin having an isocyanate compound as a curing agent. It is formed. The second coating layer 4 is made of any one of the above resins having an isocyanate compound as a curing agent, whereby the first coating layer 2 can be in an acidic atmosphere, and the polyaniline is represented by the formula (1). It can be prevented that the emeraldine salt shown is dehydrogenated to become an emeraldine base represented by the following formula (2). When polyaniline becomes emeraldine base, it becomes brittle and easily peels from the anticorrosion steel pipe 1.

  Next, the manufacturing process of the anticorrosion steel pipe 1 will be described.

  When manufacturing the anticorrosion steel pipe 1, first, as shown to Fig.3 (a), the 1st coating layer 2 is formed by apply | coating the said undercoat on the whole surface of the anticorrosion steel pipe 1. FIG.

  Next, as shown in FIG.3 (b), the said zinc tape 3b is stuck to the part used as the ground part of the 1st coating film layer 2 via the electroconductive adhesive layer 5a (not shown). Then, the anode metal layer 3 is formed.

  And as shown in FIG.3 (c), the 2nd coating film layer 4 is formed by apply | coating the said top coating material on the 1st coating film layer 2 and the anode metal layer 3. FIG. As a result, the anticorrosion steel pipe 1 shown in FIG. 1 can be obtained.

  Although the said manufacturing method shows the method of manufacturing the anticorrosion steel pipe 1 of this embodiment newly, it is good also as the anticorrosion steel pipe 1 of this embodiment by repairing the existing steel pipe.

  The existing anticorrosion steel pipe 1 is provided with an existing coating layer 6 as shown in FIG. Therefore, first, the existing coating layer 6 is peeled by sparing the portion including the ground portion of the anticorrosion steel pipe 1 to expose the steel pipe base of the peeled portion 7 and the surface of the steel pipe base is cleaned. Next, the first coating layer 2 is formed by applying the undercoat paint to the entire surface of the corrosion-resistant steel pipe 1 at the peeling portion 7.

  Next, as shown in FIG.4 (b), the said zinc tape 3b is stuck to the part used as the ground part of the 1st coating film layer 2 via the electroconductive adhesive layer 5a (not shown). Then, the anode metal layer 3 is formed.

  Next, as shown in FIG. 4C, the first coating layer 2 is formed by further applying the primer coating on the first coating layer 2 and the anode metal layer 3. As a result, the anode metal layer 3 is applied to the first coating layer 2.

  Next, as shown in FIG. 5, the second coating layer 4 is formed by applying the top coating on the first coating layer 2. And the same coating material as the coating material which forms the said existing coating layer 6 is apply | coated on the 2nd coating layer 4, and the coating layer 6a same as the existing coating layer 6 is formed. As a result, the anticorrosion steel pipe 1 shown in FIG. 1 can be obtained.

  In the present embodiment, the top coating material is one resin selected from the group consisting of epoxy resins, urethane resins, and fluorine resins, and each is made of a resin having an isocyanate compound as a curing agent. Paint is used. However, any coating material may be used as the top coating material as long as the first coating layer 2 does not peel from the anticorrosion steel pipe 1.

  Moreover, although this embodiment demonstrates the case where the metal foil 3a is stuck to the 1st coating film layer 2 via the electroconductive adhesive layer 5a or the nonelectroconductive adhesive layer 5b, it is an anode metal layer. The adhesive 3 may be used as long as it is mounted on the first coating layer 2. When the adhesive is not used, for example, the metal foil 3a cut longer than the circumference of the anticorrosion steel pipe 1 is wound from the first coating layer 2 along the circumference of the anticorrosion steel pipe 1 to form the metal foil 3a. For example, a method of overlapping and tightening end portions in the length direction of each other can be employed.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory sectional drawing which shows the structure of one Embodiment of this invention. The principal part enlarged view of FIG. Explanatory sectional drawing which shows the manufacturing process of the anticorrosion steel pipe shown in FIG. Explanatory sectional drawing which shows the repair process of the existing anti-corrosion steel pipe. Explanatory sectional drawing which shows the repair process of the existing anti-corrosion steel pipe.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Corrosion-proof steel pipe, 2 ... Coating film layer, 3 ... Anode metal layer.

Claims (4)

In a corrosion-resistant steel pipe comprising a steel pipe and an anode metal layer made of a metal that has a greater ionization tendency than steel, and the steel pipe and the anode metal layer are electrically connected,
A coating layer comprising a paint containing a conductive polymer and covering the steel pipe;
An anticorrosion steel pipe, comprising: an anode metal layer attached to a portion which becomes a ground portion on the coating layer.   2. The anticorrosion steel pipe according to claim 1, wherein the anode metal layer is made of one metal foil selected from the group consisting of zinc foil, aluminum foil, magnesium foil, and zinc-aluminum alloy foil. .   The anticorrosion steel pipe according to claim 2, wherein the metal foil is mounted on the coating layer via a conductive adhesive layer.   3. The anticorrosion steel pipe according to claim 2, wherein the metal foil is mounted on the coating layer through a non-conductive pressure-sensitive adhesive layer formed leaving a portion where the metal foil is in direct contact with the coating layer. A corrosion-resistant steel pipe characterized by being made.

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