JPH04183213A - Repairing method of coating layer - Google Patents

Abstract

PURPOSE:To repair a coating layer reliably by abutting the inside of a repairing material, incorporating conductive heating elements and an inner thermally fusible adhesive layer, on a surface to be repaired and applying a supporting material incorporating conductive heating elements thereon, and then conducting power to both heating elements. CONSTITUTION:Conductive heating elements 2 are incorporated in a base material 1 composed of the plastic such as polyethylene, polypropylene, fluororesin, or rubber such as silicon rubber, butyl rubber and a thermally fusible adhesive layer 3 is provided on the inside of the base material 1 thus forming a repairing material A. The adhesive layer 3 employs a mastic mainly composed of polyamide, polyester, other butyl rubber or isobutylene rubber. A supporting material B incorporating conductive heating elements 5 is additionally formed on the periphery of a base material 4 having identical composition with profile thereof being set larger than that of the repairing material A. The repairing material A is then abutted on a surface C to be repaired and the supporting material B is applied thereon followed by conduction of power to the conductive heating elements 2, 5. According to the method, temperature difference is suppressed over the entire repairing surface and exfoliation is prevented at the edge of the repairing material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for repairing a coating layer used when repairing a damaged part of a coating layer of an outer lining metal pipe, a rubber/plastic coated cable sheath, etc. be.

(Prior technology) When a scratch occurs on the coating layer of an outer lining metal pipe or the coating layer of a rubber/plastic coated cable sheath, a repair material with a heat-fusible adhesive layer provided on the inner surface can be applied with heat-fusible adhesive. It is known to repair the material layer by fusing it to the surface to be repaired by applying heat and pressure.Especially when working in cold regions, strong wind regions, cramped places, or high places, it is necessary to energize the repair material. The repair material may be heated by energizing the repair material by incorporating a conductive heating element therein.

FIG. 7 shows a repair method using a repair material incorporating such an electrically conductive heating element 2'.
A repair material A' with a heat-fusible adhesive layer 3' provided on the inner surface of the pipe is applied to the damaged area of the coating layer C' in the outer lining metal tube, and the repair material A' is heated while being pressurized by electricity. The heat-fusible adhesive layer 3' is partially fused to the covering layer C''.

In the repaired structure using the above repair method, if the adhesive strength at the edge e' of the repair material is low, no matter how high the adhesive strength at other parts, the peeling at the edge becomes the starting point and the entire surface peels. is caused.

Therefore, it is essential to provide sufficient adhesive strength to the bonding point between the edge e' of the repair material A' and the surface to be repaired C'.

(Problem to be Solved) However, according to the experience of the present inventor, when the above-mentioned heat-fusible adhesive layer has a high melting point, the bond between the outermost edge of the repair material and the surface to be repaired It is difficult to provide sufficient adhesive strength to the location. If the repair material is heated with electricity until the heat-fusible adhesive layer portions at the edges are sufficiently fused, the center portion of the repair material will become overheated, making it impossible to avoid thermal deterioration of the repair material.)

An object of the present invention is to enable, in a repair method using a repair material incorporating an electrically conductive heating element, the edge portions of the repair material to be sufficiently firmly adhered to the surface to be repaired.

(Means for Solving the Problems) The method for repairing a coating layer of the present invention includes a repair material that has a built-in electrically conductive heating element and has a heat-fusible adhesive layer on its inner surface. The repair material is applied to the surface to be repaired, an auxiliary material having a built-in conductive heating element is applied on the repair material so as to cover the periphery of the repair material, and the repair material and the auxiliary material are electrically heated under this condition. It is configured to do this.

(Explanation of Examples) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an example of the repair material A used in the present invention, in which 1 is a base material containing a conductive heating element 2, and 3 is a heat-fusible adhesive layer provided inside the base material 1. In the repair material of this example, the electrically conductive heating elements are arranged at regular intervals, but if desired, the density of the electrically conductive heating elements in the center can be made smaller than the density of the electrically conductive heating elements in the peripheral area.

The material of the base material 1 is selected depending on the material of the coating layer on the surface to be repaired, and includes, for example, polyethylene, polypropylene, polyvinyl chloride, ethylene vinyl acetate copolymer,
Thermoplastic plastics such as fluororesin, rubbers such as natural rubber, silicone rubber, butyl rubber, or crosslinked products thereof are used.

The material of the heat-fusible adhesive layer 3 is selected based on its adhesion to the coating layer of the surface to be repaired, for example.

Polyamide, ethylene-vinyl acetate copolymer, polyester, and mastic containing butyl rubber or isobutylene rubber as a main component can be used.

As the electrically conductive heating element 2, a resistance wire such as a nichrome wire,
Glass roving impregnated with conductive paint.

Cloth or nonwoven fabric impregnated with conductive paint is used.

FIG. 2 shows an example of the auxiliary material B used in the present invention, in which an electrically conductive heating element 5 is built into the periphery of the base material 4, and its outline is larger than that of the repair material.

In order to repair a surface to be repaired, for example, a damaged part of the lining layer of an externally lined steel pipe using the repair method of the present invention, first remove organic matter such as dirt, dust, oil, etc. adhering to the surface to be repaired by polishing and degreasing. The repair material A is removed by a mechanical method or a chemical method such as solvent degreasing followed by solution treatment, and then, as shown in FIG. Apply the auxiliary material B to cover the periphery of the repair material A, and in this state, energize the electrically conductive heating element 2 of the repair material A and the electrically conductive heating element 5 of the auxiliary material B, and press the roller. The heat-sealable adhesive M3 of the repair material A is fused to the lining layer C under pressure such as the following.

Heat leakage from the edge e to the heating element 5 of the auxiliary material B can be well reduced, and as a result, the auxiliary material Compared to the case without, the temperature difference between the temperature at the edge e of the repair material and the temperature at the center f, which is the highest temperature part of the repair material A, can be made smaller, and the temperature at the edge e of the repair material can be lowered by the temperature at the edge e of the repair material. The temperature approaches that of the central part f. Therefore, the adhesive strength of the repair material edge e can be made close to the adhesive strength of the repair material center part f, and peeling at the repair material edge e can be sufficiently reduced compared to the conventional case (without auxiliary material).

In the above embodiment, the auxiliary material molecule directly above the repair material A is
does not have a built-in conductive heating element, but even if this auxiliary material part has a built-in conductive heating element, the amount of heat generated per unit area of the auxiliary material part outside the periphery of the repair material is higher than that of the repair material. If the calorific value per unit area of the upper auxiliary material is greater, compare the temperature difference between the temperature at the edge of the repair material and the temperature at the center, which is the highest temperature part of the repair material, with the case without the auxiliary material. It can be made smaller. Therefore, as shown in FIG.
Auxiliary materials with lower density can also be used.

Furthermore, as shown in FIG. 5, even if the density of the conductive heating elements 5 in the auxiliary material B is uniform, the electricity is transmitted from the auxiliary material molecules on the repair material A to the heat-fusible adhesive layer 3 of the repair material A. The amount of heat generated is through the thermal resistance of the base material 1 of repair material A, and on the other hand,
The amount of heat transferred from the part of the auxiliary material f' around the edge of the repair material to the heat-fusible adhesive layer part of the edge e of the auxiliary material is due to direct transfer, and therefore the amount of heat in the latter is greater than that in the former. Even in this case, the temperature difference between the temperature at the edge e of the repair material and the temperature at the center f, which is the highest temperature part of the repair material, is smaller than in the case without the auxiliary material. Therefore, the heat-fusible adhesive layer at the edge e of the repair material can be sufficiently firmly fused to the surface to be repaired.

In the present invention, the auxiliary material B promotes uniformity of the temperature distribution of the repair material A, and the amount of heat generated by the auxiliary material B is the same as that of the repair material A.
The amount of heat generated can be sufficiently reduced compared to the amount of heat generated.

In the present invention, the auxiliary material B is usually removed after repair, but it is also possible to leave it as is.

The shapes of the repair material A and the auxiliary material B used in the present invention can be determined as appropriate; for example, a circular shape as shown in FIG. 6A or a rectangular shape as shown in FIG. 6B can be used. In FIG. 6A and FIG. 6B, 6 is a terminal for conducting electricity.

(Effects of the Invention) The method for repairing a coated surface of the present invention has the above-described configuration, and since the temperature difference between the edge of the repair material and the center of the repair material can be sufficiently reduced, thermal fusion at the edge of the repair material is possible. The adhesive strength between the adhesive layer and the surface to be repaired should be close to the adhesive strength between the adhesive layer and the surface to be repaired at the center of the repair material, and peeling at the edges of the repair material can be achieved. Full-face peeling of the repair material starting at the starting point can be sufficiently reduced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a repair material used in the present invention, FIG. 2 is an explanatory diagram showing an example of an auxiliary material used in the present invention, and FIG. 3 is an explanatory diagram showing an example of the present invention. Fig. 4 is an explanatory diagram showing separate auxiliary materials used in the present invention, Fig. 5 is an explanatory diagram showing another embodiment of the present invention, and Figs. 6 and 6B are respectively repair materials used in the present invention. FIG. 7 is an explanatory diagram showing a conventional example. A... Repair material, 1... Base material, 2... Electrically conductive heating element, B... Auxiliary material, 4... Base material, 5... Electrically conductive heating element, C... Surface to be repaired.

Claims (1)

[Claims] A repair material containing a built-in electrically conductive heating element and having a heat-fusible adhesive layer on the inner surface is applied to the surface to be repaired with its heat-fusible adhesive layer, and the auxiliary material containing a built-in electrically conductive heating element is applied to the surface to be repaired. A method for repairing a covering layer, which comprises applying an electric current to the repair material and the auxiliary material under such conditions.