JP7268262B1 - METHOD FOR REPAIRING DAMAGE TO ANTI-CORROSION COATING LAYER IN METAL MATERIAL - Google Patents

Abstract

INDUSTRIAL APPLICABILITY The present invention provides a repair method capable of repairing the anti-corrosion coating layer 2 on the metal material 1 by a simple method, and providing excellent stability and durability of the repaired portion. The repair method of the present invention includes a coating removal portion forming step of forming a coating removal portion 23 in which the metal material 1 is exposed by removing the damaged portion 21 of the anticorrosion coating layer 2 and the floating portion 22 around the damaged portion 21, Then, the filling polyolefin sheets (31A, 32A, 33A) are laminated and adhered as two or more sheet layers (31, 32, 33) to the cover-removed part 23 to surround the cover-removed part 23. It has at least a filling portion forming step of forming a filling portion having substantially the same height as the anticorrosion coating layer 2 . Each of the sheet layers has a seam line (31B, 32B, 33B) by joining a plurality of filling polyolefin sheets, and the seam lines of adjacent sheet layers are arranged so as not to overlap each other. do.

Description

TECHNICAL FIELD The present invention relates to a method for repairing damage to a metal material coated with an anticorrosion coating layer made of polyolefin.

Polyolefins are widely used as anticorrosive coatings for metal materials such as steel pipes because they are easy to process and have excellent durability against moisture, soil, gas, and the like.

Metal materials are subjected to various physical impacts during storage, transportation, construction, etc. At that time, the anti-corrosion coating layer of the metal material, which is anti-corrosion coated with polyolefin, may be damaged. Since the damaged part causes deterioration of the anti-corrosion property of polyolefin, it is required to repair it when damage occurs. Various methods for repairing damage have been proposed.

For example, there are several known methods of filling the exposed portion of the anticorrosion coating layer with a filler (sealant) (Patent Documents 1 to 3).

In Patent Document 1, the damaged portion formed as a recess in the anticorrosion coating layer is filled with a sealant that exhibits heat-meltability or adhesiveness and fluidity at room temperature so that the upper surface thereof is at the same level as the surface of the anticorrosion coating layer. After that, a repair member comprising an adhesive layer on one side of a crosslinked polyolefin sheet is applied to the damaged portion of the anticorrosion coating layer through the adhesive layer so as to cover the anticorrosion coating layer around the damaged portion. Then, a reinforcing heat-fusible polyolefin sheet having a softening point higher than the softening point of the adhesive used in the adhesive layer of the repair member is applied to at least the outer peripheral portion of the repair member and the outer peripheral portion. A repair method is disclosed in which the adjacent anti-corrosion coating layers are heat-pressed so as to be continuously coated.

Patent Document 2 describes a repair method in which a filler is filled in a coating damaged portion of a polyethylene-coated anti-corrosion steel material, a polyethylene sheet is placed so as to cover the filler, and the polyethylene sheet is ultrasonically welded to the polyethylene coating film on the surface of the steel material. A method is disclosed.

In Patent Document 3, a primer containing a reaction-curable resin that exhibits adhesion to polyolefin is applied to at least the sealant-contacting surface of the polyolefin anticorrosive coating layer around the exposed surface of the steel pipe, and then the sealant-contacting surface and On the exposed surface of the steel pipe, a sealant containing a reaction-curable resin that exhibits adhesiveness to the steel pipe is applied, and then a heat-shrinkable coating material with a primer applied on one side is applied so that the primer-applied surface is the sealant layer. After disposing on at least the sealant layer so as to face each other, at the latest before the completion of the curing reaction of the primer, the heat-shrinkable covering material is heated and thermally shrunk and crimped onto at least the sealant layer. disclosed.

Also known is a method of repairing a portion where the anticorrosion coating layer is exposed using a polyolefin sheet (Patent Documents 4 and 5).

In Patent Document 4, a modified polyethylene sheet is heated and pressed to cover a damaged portion of a steel mill-coated polyethylene coating layer and the surface of the coating layer around the damaged portion, and then, 2 is coated on the modified polyethylene coating layer. A repairing method is disclosed in which a layer sheet (lower layer: modified polyethylene, upper layer: polyethylene) is heat-pressed and covered.

In Patent Document 5, a primer containing an organometallic compound is applied to the damaged part of the polyolefin-coated steel material and the surrounding mill-coat polyolefin coating layer, and a repair polyolefin sheet shaped to be inserted into the damaged part is coated on one side and side surface. A primer is applied, and then an α-cyanoacrylate resin composition is applied to at least one of the primer-coated surface of the mill-coat polyolefin coating layer and the primer-coated surface of the repair polyolefin sheet in and around the damaged area, A repairing method is disclosed in which a repairing polyolefin sheet is adhered to a damaged portion with the primer-coated surfaces facing each other.

A metal material repaired by a method using a filler (sealant) as in Patent Documents 1 to 3 has a structure in which dissimilar materials (filler and polyolefin) are joined, so the temperature around the metal material rises. Under such an environment, there is a concern that the repaired part may be damaged due to the difference in thermal expansion coefficient.
In addition, as in Patent Documents 4 and 5, in the case of the method using a polyolefin sheet, in order to ensure sufficient adhesion between the polyolefin sheet and the underlying metal material or the surrounding polyolefin anti-corrosion coating layer, heating is required. There are drawbacks such as the need for special materials as adhesives and primers.

Therefore, there is a demand for the development of a repair method that can repair damage to the anticorrosion coating layer of a metal material by a simple method and that is excellent in the stability and durability of the repaired portion.

JP-A-61-170586 Japanese Patent Application Laid-Open No. 2001-129892 JP-A-61-193832 JP-A-1-95029 JP-A-1-275032

The present invention has been made in view of the above background art, and an object of the present invention is to repair the damage of the anticorrosion coating layer in the metal material by a simple method (for example, repair even by non-experts). It is another object of the present invention to provide a repair method in which the repaired portion is excellent in stability and durability.

As a result of intensive studies to solve the above problems, the present inventors found that when repairing the anticorrosion coating layer by filling the coating removal portion with a polyolefin sheet, which is the same material as the anticorrosion coating layer, the polyolefin sheet is used. It has been found that uniform adhesion is facilitated by laminating and adhering two or more sheet layers and forming each sheet layer by joining a plurality of polyolefin sheets.
When each sheet layer is composed of a plurality of sheets in this way, there is a risk that liquid such as water may enter from the seams of the sheets. The inventors have found that such a configuration can reduce the risk and ensure the stability and durability of the repaired portion, and have completed the present invention.

That is, the present invention is a method for repairing damage to a corrosion-resistant coating layer of a metal material coated with a corrosion-resistant coating layer made of polyolefin, comprising:
A coating removal portion forming step of forming a coating removal portion in which the metal material is exposed by removing the damaged portion of the anticorrosion coating layer and the floating portion around the damaged portion, and
The filling part is filled by laminating and bonding two or more sheet layers of filling polyolefin sheets to the coating-removed part to form a filling part having substantially the same height as the anti-corrosion coating layer surrounding the coating-removed part. having at least a forming step;
Each of the sheet layers has a seam line by joining a plurality of filling polyolefin sheets, and the seam lines of adjacent sheet layers are prevented from overlapping each other. A repair method is provided.

Further, in the present invention, a cover polyolefin sheet is adhered to the boundary between the filling portion and the anti-corrosion coating layer surrounding the filling portion to cover the boundary from above. The above-described repair method is provided, which includes a cover portion forming step of forming the cover portion.

In this specification, "polyolefin sheet" may be abbreviated as "sheet", "filling polyolefin sheet" as "filling sheet", and "covering polyolefin sheet" as "covering sheet".

ADVANTAGE OF THE INVENTION According to this invention, the repair method which can repair the damage of the anti-corrosion coating layer in a metal material by a simple method, and is excellent in stability and durability of the repair part can be provided.
In particular, metal materials such as steel pipes to which the present invention is applied are often used in environments where there is a lot of moisture or are exposed to chemicals. Sufficient durability can be exhibited even in places.

Since the method of the present invention does not require heating when attaching the polyolefin sheet to the metal material, it is possible to perform repairs even in locations and situations where fire must be avoided.

In the method of the present invention, the sheet to be filled in the coating-removed portion and the anti-corrosion coating layer remaining around the coating-removed portion are composed of the same polyolefin, so that the thermal expansion coefficients of both are approximately the same, and the metal Even in an environment where the temperature around the material can rise, the repaired part is less likely to be damaged.

In the method of the present invention, since the sheet layer is constructed by splicing a plurality of sheets together, the size of each sheet is relatively small. For this reason, the method of the present invention has various merits as compared with the case of filling and repairing with a single polyolefin sheet.

First, according to the method of the present invention, even an unskilled operator can easily apply the primer and the adhesive to the sheet uniformly. In addition, the method of the present invention is easy to deal with damage of various shapes. In particular, if the metal material is a curved pipe, tower or tank, if the curved surface such as a curved portion or a branch portion is damaged, the method of filling with a single polyolefin sheet will not allow the primer or adhesive to be applied evenly to the sheet. The method of the present invention facilitates the repair of such curved surfaces.

In the method of the present invention, the filling portion is formed by laminating a plurality of sheet layers. Therefore, the present invention has various merits as compared with the case where the filling portion is formed with a single sheet layer.

For example, anti-corrosion coating layers of metal materials have various thicknesses, and the method of the present invention using a plurality of sheet layers can cope with anti-corrosion coating layers of various thicknesses.

In addition, in the method of the present invention using a plurality of sheet layers, even if a problem occurs in one of the sheet layers, the effect is less likely to affect the underlying metal material.

Furthermore, in an environment where the temperature around the metal material may rise, the adhesive layer between the metal material and the polyolefin sheet is likely to deteriorate due to the difference in coefficient of thermal expansion between the metal material and the polyolefin sheet. When a plurality of sheet layers are laminated together, since there is no difference in coefficient of thermal expansion between the sheet layers, deterioration of the adhesive layer between the sheet layers is less likely to occur.

As described above, in the method of the present invention, a plurality of sheet layers are used, and each of the sheet layers is composed of a plurality of sheets joined together. The part can be made excellent in stability and durability.

It is a schematic sectional drawing of a metal material. It is a schematic sectional drawing of the vicinity of the damaged part of the anti-corrosion coating layer of a metal material. It is a schematic sectional drawing of the metal material after performing the coating removal part formation process. FIG. 4 is a plan view of the metal material after performing a coating removal portion forming step; FIG. 4 is a plan view of the metal material after performing a coating removal portion forming step; It is a schematic sectional drawing of the metal material after performing a filling part formation process. It is a schematic sectional drawing which shows the process of a filling part formation process. (a) State in which the first sheet layer is formed (b) State in which the second sheet layer is formed (c) State in which the third sheet layer is formed It is a top view which shows the process of a filling part formation process. (a) State in which the first sheet layer is formed (b) State in which the second sheet layer is formed (c) State in which the third sheet layer is formed It is a top view which shows the process of a filling part formation process. (a) State in which the first sheet layer is formed (b) State in which the second sheet layer is formed (c) State in which the third sheet layer is formed FIG. 4 is a schematic cross-sectional view of the metal material after performing a cover portion forming step; FIG. 4 is a plan view of the metal material after performing a cover portion forming step; FIG. 4 is a schematic cross-sectional view of the metal material after performing a cover portion forming step; FIG. 4 is a plan view of the metal material after performing a cover portion forming step; FIG. 10 is a schematic cross-sectional view showing the processes of a filling portion forming step and a cover portion forming step (in the case of forming a partially uncoated portion in the filling portion forming step); (a) State in which the first sheet layer is formed (a') State in which the first sheet layer is formed and then a part of the coating is removed (b) Formation of the second sheet layer state FIG. 15 is a continuation of FIG. 14; (b') After the formation of the second sheet layer, the partially uncoated portion is formed (c) The state after the third sheet layer is formed (d) After the cover part forming step is performed situation

Although the present invention will be described below, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented.

The present invention relates to a method for repairing damage to the anticorrosion coating layer 2 of a metal material 1 coated with the anticorrosion coating layer 2 made of polyolefin. FIG. 1 shows a schematic sectional view of a metal material 1 before repair according to the present invention. A metal material 1 is coated with an anti-corrosion coating layer 2 made of polyolefin.

There is no particular limitation on the type of metal that constitutes the metal material 1, and examples thereof include iron, aluminum, copper, zinc, and steel.

The shape of the metal material 1 is also not particularly limited, and examples thereof include a metal plate, a metal tube, a metal rod, and a metal container such as a tank.

When the metal material 1 is a metal pipe, the metal pipe may have the anticorrosion coating layer 2 on the inner surface, the anticorrosion coating layer 2 on the outer surface, or both the inner surface and the outer surface. may have a metal layer on the The repair method of the present invention can be applied to the anti-corrosion coating layer 2 on either the inner surface or the outer surface.
Moreover, when the metal material 1 is a metal pipe, the metal pipe may be a straight pipe, a bent pipe (a metal pipe having a bent portion), a branch pipe, a reducer, or the like.

When the metal material 1 is a metal pipe, the inner diameter is not particularly limited. The inner diameter of the metal tube is, for example, 20 cm or more, 40 cm or more, or 50 cm or more, and 10 m or less, 5 m or less, or 3 m or less.

If the metal material 1 is a steel pipe whose inner surface and/or outer surface is coated with the anticorrosive coating layer, especially if the steel pipe is a steel pipe for transporting liquids (water, chemicals, etc.), damage occurs. Since there are many opportunities and such steel pipes are widely used, the advantage of the present invention that a repaired portion with excellent stability and durability can be formed by a simple method is likely to be utilized.

When the metal material 1 is a steel pipe, more specific examples include an electric resistance welded steel pipe, a butt-welded steel pipe, a plated steel pipe, a seamless steel pipe, a spiral steel pipe, and a UOE steel pipe, but are not limited to these.

The anti-corrosion coating layer 2 is made of polyolefin and serves to protect the metal material 1 from corrosion and impact.

There are no particular restrictions on the polyolefin used as the raw material for the anticorrosion coating layer 2, and examples include low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, polybutene, and copolymers thereof.
One of these may be used alone to form the anticorrosion coating layer 2, or two or more of them may be used in combination to form the anticorrosion coating layer 2.

The thickness of the anti-corrosion coating layer 2 (hereinafter, “thickness” in this specification means the average thickness unless otherwise specified) is preferably 0.5 mm or more, and is 1 mm or more. is more preferable, 1.2 mm or more is particularly preferable, and 1.5 mm or more is most preferable. Moreover, it is preferably 5 mm or less, more preferably 4.5 mm or less, and particularly preferably 4 mm or less.
When the thickness is at least the above lower limit, the corrosion resistance and impact resistance are excellent. Moreover, it is advantageous in cost in thickness being below the said upper limit.

In the repair method of the present invention, first, the coating removal portion forming step is performed. In the coating-removed portion forming step, the damaged portion 21 of the anticorrosion coating layer 2 and the floating portion 22 around the damaged portion 21 are removed to form the coating-removed portion 23 where the metal material 1 is exposed.

FIG. 2 is a schematic cross-sectional view showing the vicinity of the damaged portion 21 of the anticorrosion coating layer 2 of the metal material 1. As shown in FIG. A damaged portion 21 is generated in the anticorrosive coating layer 2 due to contact with other materials during storage or transportation, contact with tools during maintenance, or the like. It can be visually confirmed that the periphery of the damaged portion 21 is in a state of being raised from the surface of the surrounding anticorrosion coating layer 2 (a raised portion 22) (in addition, in FIG. 2, the damaged portion 21 and The raised portion 22 is exaggerated).

In the coating removal portion forming step, the damaged portion 21 and the floating portion 22 around the damaged portion 21 are removed.
The floating portion 22 can be removed by a known method using a cutter, scissors, an electric tool, or the like.

FIG. 3 shows a schematic cross-sectional view of the metal material 1 after the coating removal portion forming step, and FIG. 4 shows a plan view thereof. In the portion from which the damaged portion 21 and the floating portion 22 have been removed, the anticorrosion coating layer 2 is removed and the metal material 1 is exposed (coating removed portion 23).

In the coating removal portion forming step, at least the anticorrosion coating layer 2 of the damaged portion 21 and the raised portion 22 (that is, a portion that can be visually confirmed to be in a state of being raised from the surface of the surrounding anticorrosion coating layer 2) Although it is removed, the anticorrosion coating layer 2 including the anticorrosion coating layer 2 on the outside of the floating portion 22 may be removed with a margin (too much).

Moreover, when the shape of the cover-removed portion 23 is random as shown in FIG. 4 , it becomes necessary to cut a regular-shaped polyolefin sheet according to the shape of the cover-removed portion 23 in the filling portion forming step described later. In order to reduce the trouble of such cutting, the anticorrosion coating layer 2 including the anticorrosion coating layer 2 outside the floating portion 22 is removed to form, for example, a rectangular coating removal portion 23 as shown in FIG. You may make it

The area of the coating-removed portion 23 is preferably 50 cm ² or more, more preferably 75 cm ² or more, and particularly preferably 100 cm ² or more. Also, it is preferably 500 cm ² or less, more preferably 400 cm ² or less, and particularly preferably 300 cm ² or less.

In the repair method of the present invention, the filled portion forming step is performed after the coating removed portion forming step. In the filling portion forming step, the filling polyolefin sheets (31A, 32A, 33A) are laminated and adhered as two or more sheet layers (31, 32, 33) to the coating removal portion 23, and the coating is removed. A filling portion 3 having substantially the same height as the anti-corrosion coating layer 2 surrounding the portion 23 is formed.

FIG. 6 shows a schematic cross-sectional view of the metal material 1 after performing the filling portion forming step. By performing the filling portion forming step, the polyolefin sheet is filled in the portion that was the coating removed portion 23 formed by removing the damaged portion 21 and the floating portion 22 around the damaged portion 21.

In the filling portion forming step, the filling polyolefin sheets (31A, 32A, 33A) are laminated as two or more sheet layers (31, 32, 33) on the coating removal portion 23, and each of the sheet layers (31, 32 , 33) has a seam line by joining a plurality of filling polyolefin sheets (31A, 32A, 33A), and the seam line (31B, 32B, 33B) is formed between adjacent sheet layers. ) should not overlap.

7, 8, and 9 show a specific example of the filling portion forming process, taking as an example the case where the number of sheet layers laminated on the coating removal portion 23 is three.

First, a first sheet layer 31 is formed by adhering a filling polyolefin sheet 31A onto the metal material 1 exposed at the coating removal portion 23 (Fig. 7(a), Fig. 8 ( a), FIG. 9(a)).
As shown in FIGS. 8(a) and 9(a), the first sheet layer 31 is formed by joining a plurality of filling polyolefin sheets 31A, and the sheet layer 31A is formed between the sheets 31A. , a seam line 31B is formed.

As the sheet 31A, a commercially available standard-shaped (for example, rectangular) polyolefin sheet is cut according to the shape of the cover-removed portion 23 and used. In the coating-removed portion forming step, for example, when the shape of the coating-removed portion 23 is formed into a rectangle as shown in FIG. 5, the first sheet layer 31 is also rectangular as shown in FIG. The labor for cutting the sheet in the filling portion forming process can be reduced.

After forming the first sheet layer 31, a filling polyolefin sheet 32A is adhered thereon to form a second sheet layer 32 (FIGS. 7(b) and 8(b). ), FIG. 9(b)).
As shown in FIGS. 8(b) and 9(b), the second sheet layer 32 is also composed of a plurality of filling polyolefin sheets 32A joined together, and the gap between the sheets 32A and 32A is , a seam line 32B is formed.

Here, the seam line 32B in the second sheet layer 32 is formed so as not to overlap the seam line 31B in the first sheet layer 31 (adjacent sheet layer) (see FIG. 8). In (b) and FIG. 9(b), the one-dot chain line indicates the seam line 31B in the first sheet layer 31).
By preventing the seams of vertically adjacent sheet layers from overlapping each other, when liquid such as water comes into contact with the filling part 3, the liquid reaches the lower sheet layer and even the metal material 1. becomes difficult to enter, and the stability and durability of the collecting part are improved.

In order to more easily prevent intrusion of liquids such as water, it is preferable that the positions of the seam lines (seam line 32B and seam line 31B) of vertically adjacent sheet layers are separated as much as possible. For example, as shown in FIGS. 8(b) and 9(b), it is desirable to form the seam line 32B at a position about midway between the two seam lines 31B.

After forming the second sheet layer 32, a filling polyolefin sheet 33A is adhered thereon to form a third sheet layer 33 (FIGS. 7(c) and 8(c). ), FIG. 9(c)).
As shown in FIGS. 8(c) and 9(c), the third sheet layer 33 is also composed of a plurality of filling polyolefin sheets 33A joined together, and the gap between the sheets 33A and 33A is , a seam line 33B is formed.

As in the case of the second sheet layer 32, also in the third sheet layer 33, the seam line 33B overlaps the seam line 32B in the second sheet layer 32 (adjacent sheet layer). They are formed so as not to match each other (in addition, in FIGS. 8(c) and 9(c), the seam line 32B in the second sheet layer 32 is indicated by the dashed line).

In order to make it easier to prevent the intrusion of liquids such as water, it is better that the seam line 33B and the seam line 32B are separated as much as possible. , seam line 33B is preferably formed at a location about halfway between the two seam lines 32B. That is, the position of the seam line 33B of the sheet layer 33 of the third layer may be substantially the same as the position of the seam line 31B of the sheet layer 31 of the first layer.

When the number of sheet layers is three, by forming the third sheet layer 33, the filling part 3 is formed in the damaged part 21 of the anticorrosion coating layer 2 of the metal material 1 and its surroundings. becomes (Fig. 6).

The anticorrosion coating layer 2 is made of polyolefin, and the filling portion 3 is formed by adhering a filling polyolefin sheet. Therefore, the coefficient of thermal expansion of the filling portion 3 and that of the anticorrosion coating layer 2 around it are about the same, and even in an environment where the temperature around the metal material 1 can rise, the metal material repaired by the method of the present invention can be used. Repair parts are not easily damaged.

Specific examples of the polyolefin resin that is the raw material of the anticorrosive coating layer 2 are as described above. It is desirable that the polyolefin constituting the anticorrosion coating layer 2 and the polyolefin constituting the filling polyolefin sheets (31A, 32A, 33A) are chemically the same. That is, a polyolefin sheet chemically identical to the polyolefin constituting the anticorrosion coating layer 2 of the metal material 1 to which the method of the present invention is applied is selected and used as the filling polyolefin sheets (31A, 32A, 33A). is desirable.
By doing so, it becomes easier to prevent damage to the repaired portion in an environment where the temperature around the metal material 1 may rise.

In the filling portion forming step, the polyolefin sheet for filling is laminated as two or more sheet layers.
The number of sheet layers is desirably two, three or four. If the number of sheet layers is 5 or more, the working time is increased, and the number of adhesion points increases, which may reduce the stability and durability of the repaired portion.

In the filling portion forming step, a commercially available standard-shaped (for example, rectangular) polyolefin sheet is cut as necessary and used.

The thickness of the regular-shaped polyolefin sheet is preferably 0.1 mm or more, more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more. Moreover, it is preferably 5 mm or less, more preferably 4 mm or less, and particularly preferably 3 mm or less.
When the thickness is within the above range, the number of sheet layers is likely to be within the above desirable range.

The area of one regular-shaped polyolefin sheet is preferably 50 cm ² or more, more preferably 75 cm ² or more, and particularly preferably 100 cm ² or more. Also, it is preferably 500 cm ² or less, more preferably 400 cm ² or less, and particularly preferably 300 cm ² or less.
When the area is at least the lower limit, workability (work time) is likely to be improved. When the area is equal to or less than the above upper limit, the adhesive and the primer can be evenly applied to the sheet, and peeling of the sheet is less likely to occur.

A regular-shaped polyolefin sheet is used after being cut according to the shape of the cover-removed portion 23. Especially when the shape of the cover-removed portion 23 is a random shape as shown in FIG. Although the area may fall below the above lower limit, there is no particular problem.

Adhesion in the filling portion forming step is desirably performed by applying a primer to the filling polyolefin sheet, drying the primer, and then applying an adhesive to the filling polyolefin sheet.

The first sheet layer 31 is formed by adhering a sheet 31A onto the metal material 1 exposed at the coating removed portion 23 . Coating the sheet 31A with the primer or adhesive rather than coating the metal material 1 with the primer or the adhesive makes it possible to apply the primer or the adhesive more uniformly, thereby improving the adhesiveness.

The second and subsequent sheet layers are formed by bonding polyolefin sheets together. In this case, the primer or adhesive may be applied to the existing polyolefin sheet constituting the sheet layer, to the newly installed polyolefin sheet, or to both polyolefin sheets. good.
From the viewpoint of improving adhesion, it is desirable to apply a primer or an adhesive to both polyolefin sheets.

Adhesion between the adhesive and the surface to be adhered can be improved by applying a primer to the surface to be adhered, such as a polyolefin sheet, prior to applying the adhesive.
Specific examples of primers used in the filling portion forming step include amine-based primers, synthetic rubber-based primers, acrylic primers, urethane-based primers, and epoxy-based primers.
These primers may be used singly or in combination of two or more. From the viewpoint of work efficiency, it is desirable to use one type alone.

The coating amount of the primer used in the filling portion forming step is preferably 0.1 g/m ² or more, more preferably 0.5 g/m ² or more, and 1.0 g/m ² or more. is particularly preferred. Also, it is preferably 6.0 g/m ² or less, more preferably 3.0 g/m ² or less, and particularly preferably 2.0 g/m ² or less.
When the coating amount is at least the above lower limit, workability (working time) is likely to be improved, and it is advantageous in terms of cost. When the area is equal to or less than the above upper limit, the adhesiveness is likely to be improved.

After applying the primer, the adhesive is applied over the primer. As for the timing of applying the adhesive, the time interval between the completion of the application of the primer and the start of application of the adhesive is preferably 0.5 minutes or more, more preferably 1 minute or more, and 2 minutes or more. is particularly preferred. Also, it is preferably 10 minutes or less, more preferably 7 minutes or less, and particularly preferably 5 minutes or less.

Specific examples of adhesives used in the filling portion forming step include polyvinyl acetate-based adhesives, cyanoacrylate-based adhesives, cellulose-based adhesives, polyester-based adhesives, polyether-based adhesives, polyamide-based adhesives, Polyimide-based adhesives, epoxy-based adhesives, urethane-based adhesives, rubber-based adhesives, silicone-based adhesives, and the like can be exemplified.
These adhesives may be used individually by 1 type, and may use 2 or more types together. From the viewpoint of work efficiency, it is desirable to use one type alone.

The amount of adhesive used in the filling portion forming step is preferably 20 g/m ² or more, more preferably 30 g/m ² or more, and particularly preferably 40 g/m ² or more. Also, it is preferably 70 g/m ² or less, more preferably 60 g/m ² or less, and particularly preferably 50 g/m ² or less.
When the coating amount is at least the above lower limit, workability (working time) is likely to be improved, and it is advantageous in terms of cost. When the area is equal to or less than the above upper limit, the adhesiveness is likely to be improved.

In the filling portion forming step, the surface of the metal material 1 exposed at the coating removal portion 23 is roughened with sandpaper or the like in order to improve adhesion prior to placing the polyolefin sheet. It is desirable to Moreover, it is desirable to wash the surface of the metal material 1 after surface roughening with a solvent such as acetone and a waste cloth to remove rust and foreign substances.
Also, it is desirable to roughen and clean the polyolefin sheet placed in the coating removal section 23 in the filling section forming step in the same manner. From the standpoint of work efficiency and adhesiveness, it is particularly desirable to perform surface roughening and washing on both sides of the polyolefin sheet in advance before installation.

In the repair method of the present invention, the cover portion forming step may be performed after the filling portion forming step.
In the cover portion forming step, the cover polyolefin sheet 41 is adhered to the boundary portion 34 between the filling portion 3 and the anti-corrosion coating layer 2 surrounding the filling portion 3, and the boundary portion 34 is placed from above. A cover portion 4 for covering is formed (FIGS. 10 and 12).

In the filling portion 3 of the metal material 1 (FIG. 6) after performing the filling portion forming step, the seams of the vertically adjacent sheet layers are prevented from overlapping, so that the sheet layer on the lower layer side is prevented from overlapping. In addition, it is possible to make it difficult for liquids such as water to enter the metal material 1. However, liquids such as water are prevented from entering the metal material 1 via the boundary portion 34 between the filling portion 3 and the anticorrosive coating layer 2 surrounding the filling portion 3. It may penetrate the metal material 1.
By performing the cover portion forming step, the boundary portion 34 is covered from above, making it easier to prevent liquid such as water from entering.

In the cover portion forming step, a cover polyolefin sheet 41 is installed by adhering it on the boundary portion 34 between the filling portion 3 and the anticorrosion coating layer 2 .
In the cover forming step, as shown in FIGS. 10 and 11 , one cover polyolefin sheet 41 is used to cover (the uppermost sheet layer of) the filling portion 3 and the boundary portion 34 to form the cover portion 4 . Alternatively, as shown in FIGS. 12 and 13, a plurality of polyolefin sheets for covering are used to cover only the portion necessary to cover the border 34, and the uppermost sheet of the filling portion 3 ( layer) may be left uncovered.
Moreover, the shape of the cover polyolefin sheet 41 need not be rectangular as shown in FIGS.

The thickness of the cover polyolefin sheet 41 is preferably 0.1 mm or more, more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more. Moreover, it is preferably 5 mm or less, more preferably 4 mm or less, and particularly preferably 3 mm or less.

As shown in FIGS. 10 and 11, when one cover polyolefin sheet 41 is used, the area of the cover polyolefin sheet 41 is preferably 100 cm ² or more, more preferably 150 cm ² or more. 200 cm ² or more is particularly preferred. Also, it is preferably 1000 cm ² or less, more preferably 800 cm ² or less, and particularly preferably 600 cm ² or less.

As shown in FIGS. 12 and 13, when a plurality of cover polyolefin sheets 41 are used, the area of each cover polyolefin sheet 41 is preferably 50 cm ² or more, more preferably 75 cm ^{2 or} more. is more preferable, and 100 cm ² or more is particularly preferable. Also, it is preferably 500 cm ² or less, more preferably 400 cm ² or less, and particularly preferably 300 cm ² or less.

Adhesion in the cover portion forming step is also desirably performed by applying a primer to the cover polyolefin sheet 41, drying the primer, and then applying an adhesive to the cover polyolefin sheet 41. FIG.

In the adhesion in the cover portion forming step, a primer or adhesive may be applied to the filling polyolefin sheet (33A in the examples shown in FIGS. 7, 8, and 9A) which is the outermost layer of the filling portion 3. , the cover polyolefin sheet 41, or both polyolefin sheets.
From the viewpoint of improving adhesion, it is desirable to apply a primer or an adhesive to both polyolefin sheets.

Specific examples of primers and adhesives used for bonding in the cover portion forming step, preferred application amounts thereof, and the time interval from the completion of primer application to the start of adhesive application are described in the above-described filling portion forming step. is the same as

Only one surface of the cover polyolefin sheet 41 used in the cover portion forming step is roughened, and the roughened surface is used as the adhesive surface for the filling portion 3 and the anticorrosion coating layer 2 . It is desirable (it is pointless to roughen the surface of the cover polyolefin sheet 41 other than the adhesive surface).

In the filling portion forming step of the present invention, before forming the second and subsequent sheet layers, the anti-corrosion coating layer 2 around the sheet layer below it is formed to have substantially the same height as the "lower sheet layer". A partially uncoated portion 24 may be formed, which is removed so as to be flat.
A specific example of such a process is shown in FIGS. 14 and 15. FIG.

The formation of the first sheet layer 31 is the same as the case shown in FIG. 7(a) (FIG. 14(a)).

After forming the first sheet layer 31, the anti-corrosion coating layer 2 around the sheet layer 31 is removed to form a partially coated removed portion 24 (FIG. 14(a')). At this time, the anticorrosion coating layer 2 is removed so that the height of the anticorrosion coating layer 2 below the part of the coating removal portion 24 is substantially the same as the height of the first sheet layer 31 .

After forming the partially coated portion 24, a second sheet layer 32 is formed on the first sheet layer 31 (FIG. 14(b)). When forming the second sheet layer 32 , the filling polyolefin sheet 32</b>A is filled so as to include the partially uncoated portion 24 .
Preventing the seam line 32B of the second sheet layer 32 from overlapping with the seam line 31B of the first sheet layer 31 is the same as in the case shown in FIG. 7(b).

After forming the second sheet layer 32, the anti-corrosion coating layer 2 around the sheet layer 32 is similarly removed to form a partial coating removal portion 24 (FIG. 15(b')). Next, the third sheet layer 33 is formed by filling the filling polyolefin sheet 33A so as to include the partly coated removed portion 24 (FIG. 15(c)).

After forming the third sheet layer 33 (that is, after completing the filling portion forming step), the cover portion forming step may be performed (FIG. 15(d)).

In the filling portion forming step, by forming the partially uncovered portion 24 before forming the second and subsequent sheet layers, the filling portion 3 is formed as shown in FIGS. The shape of is mortar-like.
By doing so, the boundary portion 34 between the filling portion 3 and the anti-corrosion coating layer 2 surrounding the filling portion 3 is not aligned, so that the intrusion of liquid from the boundary portion 34 can be more effectively prevented. can be done.

The repair method of the present invention can repair damage to the anticorrosion coating layer of a metal material by a simple method, and can provide a repair method in which the repaired part has excellent stability and durability. Metal materials repaired by the repair method of the present invention include water pipes for transporting water supply and sewage, agricultural water, industrial water, etc.; pipes for chemicals and cooling water in factories, plants, etc.; gas, electricity, oil, etc. It is widely used for repairing steel pipes that constitute transportation pipelines, etc.

1 metal material 2 anti-corrosion coating layer 3 filling part 4 cover part 21 damaged part 22 floating part 23 coating removed part 24 partially coated removed part 31 sheet layer (first layer)
31A Polyolefin sheet for filling (first layer)
31B seam line (first layer)
32 sheet layer (second layer)
32A filling polyolefin sheet (second layer)
32B seam line (second layer)
33 sheet layer (third layer)
33A filling polyolefin sheet (third layer)
33B seam line (third layer)
34 boundary part 41 polyolefin sheet for cover

Claims (7)

A method for repairing damage to a corrosion-resistant coating layer of a metal material coated with a corrosion-resistant coating layer made of polyolefin, comprising:
A coating removal portion forming step of forming a coating removal portion in which the metal material is exposed by removing the damaged portion of the anticorrosion coating layer and the floating portion around the damaged portion, and
The filling part is filled by laminating and bonding two or more sheet layers of filling polyolefin sheets to the coating-removed part to form a filling part having substantially the same height as the anti-corrosion coating layer surrounding the coating-removed part. having at least a forming step;
Each of the sheet layers has a seam line by joining a plurality of filling polyolefin sheets, and the seam lines of adjacent sheet layers are prevented from overlapping each other. Repair method. Furthermore, a cover is provided by adhering a cover polyolefin sheet on the boundary between the filling portion and the anti-corrosion coating layer surrounding the filling portion to form a cover portion that covers the boundary from above. The repair method according to claim 1, comprising a part forming step. 3. Adhesion in the filling part forming step is performed by applying a primer to the filling polyolefin sheet, drying the primer, and then applying an adhesive to the filling polyolefin sheet. Described repair method. The repair method according to claim 1 or 2, wherein the polyolefin forming the anticorrosion coating layer and the polyolefin forming the filling polyolefin sheet are chemically the same. The repair method according to claim 1 or 2, wherein the anticorrosion coating layer has a thickness of 0.5 mm or more and 5 mm or less. The repair method according to claim 1 or 2, wherein the metal material is a steel pipe whose inner surface and/or outer surface is coated with the anticorrosive coating layer. The repair method according to claim 6 , wherein the steel pipe is a steel pipe for transporting liquid.

Images