JPS63274786A - Formation of corrosion preventive coating layer - Google Patents

Abstract

PURPOSE:To enhance the corrosion preventing effect of a corrosion preventive coating material when a steel material is coated with rubber, plastics or the like to prevent corrosion, by interposing metallic powder for a galvanic anode for electrolytic protection between the steel material and the corrosion preventive coating layer. CONSTITUTION:While a steel pipe 1 is rotated with turning rollers 5, a soln. 2 of a primer in toluene or the like is applied to the pipe 1 with a roller brush or the like, powder 3 of a metal such as Mg or Mn is stuck from a metallic powder feeder 6 and a corrosion preventive coating layer 4 of rubber, plastics or the like is wound. The metallic powder layer acts as a galvanic anode and the corrosion of the steel pipe 1 can be effectively prevented even when the corrosion preventive coating material 4 such as rubber is scratched or damaged.

Description

[Detailed description of the invention] The present invention relates to a method for forming an anticorrosive coating layer.

Traditionally, steel pipes and steel structures that are mainly installed underwater or underground have been protected from external chemical and electrical corrosion by using organic insulating materials, such as anticorrosive tapes, anticorrosive sheets, anticorrosive tubes, and extruded materials. Direct coating or the like is applied to provide an anti-corrosion coating layer.

However, no matter how thorough the construction is, scratches and damaged areas are likely to occur in the formed anticorrosion coating layer, so even if such areas occur, corrosion will not progress. To prevent corrosion, cathodic protection measures may be used.

However, taking the trouble to take precautions against cathodic corrosion is costly, so methods and configurations have been devised, such as wrapping a metal foil for a galvanic anode on the bonding surface of the anticorrosion tape.

However, such conventional methods and configurations have many problems as follows. In other words, for tapes with metal foil attached, in order to prevent the metal foil from coming off the tape, it is necessary to wrap the tape without raising its tensile strength or to make the tape material in advance from a material with low elongation. There is.

In any case, it is difficult to wrap or attach the metal foil tightly to the object to be protected. Even if it can be attached or wrapped, the adhesion of the metal foil part is insufficient and it is susceptible to external stress. There is a risk that the entire tape may be misaligned.

On the other hand, the commonly used cathodic protection method is extremely expensive and sometimes poses problems.

The present invention solves the problems of the conventional method of forming an anti-corrosion coating layer, that is, the method of cathodic protection, and provides another method of forming an anti-corrosion coating layer that is simple, inexpensive, and highly effective. This is what I am trying to do.

As a result of extensive studies, the inventors of the present invention have found that a single layer of primer containing metal powder such as magnesium or manganese is formed and interposed between the surface of the steel body whose surface is to be protected against corrosion and the anticorrosion coating layer that covers the outside thereof. The present inventors have discovered that a good cathodic protection effect can be exerted and the corrosion of copper bodies can be effectively suppressed, and the present invention has been completed.

As shown in the drawings, the method for forming an anti-corrosion coating layer of the present invention is to apply a single piece of rubber or plastic or other material onto a steel material 1, 11 of a desired shape such as a plate or pipe. When coating the anti-corrosion coating material such as a composite with a substance, the metal powder 3, 13 for cathodic protection galvanic anode is uniformly injected or sprinkled between the anti-corrosion coating material to be coated and the steel materials 1, 11. It is characterized in that the anticorrosive coating material layers 4 and 14 are integrally formed by coating the coating material.

That is, when the steel material to be protected against corrosion 1.11 is a steel pipe 1 and an anticorrosive coating N4 of an insulating tape is formed, one method for winding the tape is a device called a turning roller (see Fig. 3). The above-mentioned steel pipe 1 is placed on this, and by rotating it, an anti-corrosion coating is formed by supplying a primer, an undercoat, a tape, and a metal foil onto a truck or the like that moves backward along the pipe. The method is to first apply a layer of primer 2 to a steel pipe 1 using a roller brush or the like, and then drop the necessary amount of magnesium or manganese powder 3, which is used in the galvanic anode material, from a metal powder supply device 6 onto the primer. Next, roll tape 4. There are various materials for the primer 2 and tape 4, but for example, the tape is made of a polyethylene film with a butyl rubber adhesive pasted on one side, and the primer is made by dissolving the tape's adhesive in toluene or the like. etc. With such a method and configuration, a metal material for the galvanic anode can be easily inserted at a cost of about the same as the material cost. Similarly, in the line traveling machine method (see Figure 5), which is another tape winding method, metal powder is applied from the metal powder supply device 26 to the primer coated surface between the time the primer is applied and the tape is wound. If you spray it on, you can get something similar.

In addition, similar to the case of the steel pipe, the same can be done in the case of the steel plate 11.

FIG. 3 is a schematic diagram showing an automatic device for pasting and forming the anti-corrosion coating layer 4 on the outer wall of the steel pipe 1, and FIG. 4 is shown being formed by the pressure roll 17.

The effect of the method of the present invention will be shown in one example.

The results of a cross-cut test conducted on anticorrosive layers formed by applying primers and anticorrosive tape to steel plates using the method of the present invention and the conventional method are shown below.

○: No rust visible, Δ Some rust, × Obvious rust Salt Water: 3% salt water Primer: Synthetic resin enamel paint solid content 20% Coating amount: 100 g/m2 Tape: Polyethylene butyl rubber anticorrosion tape 0.
5 mark metal powder: Toyo Aluminum FM 15 g/m" As described above, according to the method for forming an anti-corrosion coating layer of the present invention, anti-corrosion coated steel sheets and anti-corrosion coated steel pipes can be obtained relatively easily and effectively. Also, there is no need for a special metal powder supply device, and since the anti-corrosion coated steel pipes and steel plates have a structure in which a single layer of primer containing metal powder is interposed between the copper body and the anti-corrosion coating layer, It can be obtained at a low cost, and there is no cost for subsequent lining.Therefore, corrosion-resistant steel pipes and steel plates that also have the effect of cathodic protection can be obtained for a small amount plus the cost of metal powder. By adding these metal powders of aluminum and manganese, even if there are large scratches in the coating layer, the electrolytic protection effect will work and corrosion of the steel body can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a part of the steel pipe coating layer after construction according to one embodiment of the present invention, and FIG. 2 is a sectional view of a steel plate after construction according to another embodiment of the present invention. FIG. 3 is a cross-sectional view of a part of the coating layer, FIG. 3 is a perspective view showing a state in which a tape is wound around a turning roller according to an embodiment of the present invention, and FIG. FIG. 5 is a perspective view showing a state in which sheets are pasted together using such a conveyor, and FIG. 5 is a schematic explanatory diagram showing a state in which a tape is wound by a traveling machine method according to an embodiment of the present invention. 1... Steel material to be protected against corrosion (steel pipe) 2... Primer layer 3... Metal powder for cathodic protection galvanic anode 4... Corrosion protection coating layer 5... Turning roller 6... Metal powder supply device 11 ... Steel material to be protected from corrosion (steel plate) 12 ... One layer of primer 13 ... Metal powder 14
... Corrosion prevention sheet 15 ... Conveyor 16 ... Metal powder supply device 17 ... Pressure roller 21 ... Steel material to be protected from corrosion (steel pipe) 26 ... Metal powder supply device S: 1't Fig. 4 Figure 5

Claims (1)

[Claims] 1. When coating a steel material of a desired shape such as a plate or pipe with an anti-corrosion coating material such as rubber or plastic alone or a composite of this and other substances, the anti-corrosion coating material to be coated and the steel material. A method for forming an anti-corrosion coating layer, which comprises integrally forming an anti-corrosion coating layer by coating the coating material while uniformly injecting or spreading metal powder for electrolytic galvanic anodes between the electrodes.