JPS6145514B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating the inner surface of various metal pipes, such as those for city gas, natural gas, petroleum, water, and the like.

In the above method, in order to improve the adhesion of the coating material to the inner wall surface of the pipe, a pretreatment is performed to remove rust etc. from the treated surface, and after this pretreatment is completed, the coating material is internalized by an object passing inside the pipe. Methods such as attaching the coating material to the wall surface or transferring the coating material spray in a pipe are used.

However, this method requires two steps: pretreatment and coating treatment, and if the viscosity of the coating material is increased, the resistance to passage of objects increases, or it becomes difficult to spray, and it is difficult to apply the coating material uniformly. On the other hand, if the viscosity is lowered, a highly uniform adhesion can be obtained at the initial stage of the coating, but by the time it solidifies, it will run off the inner wall surface and harden, reducing the reliability of the coating process. Not only is it lacking in properties, but it also has the disadvantage of essentially narrowing or blocking the tube.

In view of the above-mentioned circumstances, the present invention provides a method that can perform a highly uniform coating process while simplifying the coating process.

Next, embodiments of the present invention will be described in detail based on illustrative drawings.

As shown in Figure 1A, an existing metal pipe 1 with vertical and horizontal bends is closed at both ends with gate valves 2, which are originally provided or installed as necessary. In between, a part of the metal tube 1 is cut or removed to open the end, and an object 3a for discharging the existing fluid a in the tube is put into the tube, and a chemical b for ionizing the tube-forming metal from the tank 4 is introduced. The space behind the powder 3a is filled and supplied by the pressurized supply device 5, and the substance 3a is force-fed by the medicine b to replace the existing fluid a and the medicine b. As shown in b, filler b
The pressurized supply device 5 supplies the object 3b for discharging the
The discharged drug b is collected into the recovery device 6, and at the same time, the drug b is attached to the inner wall surface of the metal tube 1, and the tube-forming metal on the inner wall surface is ionized.

This ionization cleans the inner wall surface of the metal tube 1.

Next, as shown in FIG. The liquid ionomer c that undergoes a crosslinking reaction is supplied from the tank 10 to the mixer 11, and the liquid ionomer c is atomized and transported by the airflow from the supply air blower 8 to the discharge blower 9, and is adhered to the chemical b attached to the inner wall surface, and the liquid ionomer c is crosslinked via the metal salt generated by the adhered chemical b, and as a result, as shown in FIG. Ionomer resin coating layer A over the entire inner wall surface
It is used to mold.

According to this method, the property of the liquid ionomer c is such that as crosslinking progresses through the metal salt, the viscosity increases at once and solidifies.
Even if a low-viscosity liquid ionomer c is used, a highly uniform ionomer resin coating layer A can be applied over the entire inner wall surface of the metal tube 1 while suppressing the liquid ionomer c from flowing down from the inner wall surface. By means of cross-linking the ionomer c via a metal salt, that is, by attaching the drug b to the inner wall surface of the metal tube 1 to ionize the tube-forming metal, the inner wall surface can be simultaneously pickled to remove rust, etc. Therefore, the pretreatment step can be substantially omitted.

Furthermore, the metal salt produced by the adhesion agent a acts as a crosslinking agent between the ionomer c and the metal surface, allowing coating treatment to be performed in a state where the two are firmly adhered to each other in the form of ionic bonds.

As the drug b, phosphoric acid, sodium phosphate-hydrogen, phosphoric acid aqueous solution such as sodium dihydrogen phosphate aqueous solution, etc. can be used, and liquid ionomer c can be used.
As such, metal salts of acrylic acid monomers, metal salts of acrylate oligomers, aqueous solutions of acrylates, etc. can be used. If a divalent metal salt of acrylic acid is selected as the ionomer c, the polymer produced after the polymerization reaction becomes water-insoluble, making it highly water resistant; if a polyvalent metal salt of acrylic acid is selected, the coating Since Layer A has a three-dimensional network structure, it can be made into a strong coating with excellent water and chemical resistance.

In addition, when using an aqueous solution of acrylates,
Since its viscosity is low and its permeability is high, it has the advantage of easily penetrating into voids such as rust.

If it is necessary to adjust the polymerization reaction rate of liquid ionomer c, it is possible to add a redox agent such as ammonium persulfate or sodium thiosulfate, which is a combination of an oxidizing agent and a reducing agent, to drug b or ionomer c in an appropriate ratio. , the reaction rate can be controlled.

In order to make the chemical agent b adhere to the inner wall surface of the metal tube, it is possible to use means such as spraying the chemical agent b or applying it using a coating device that passes through the inside of the tube.

Furthermore, the ionomer c can also be attached by an object passing through the tube 1.

Further, the unreacted liquid ionomer c coming out of the exhaust blower 9 can be circulated to the supply air blower 8 and reused.

In summary, the method for coating the inner surface of a metal tube according to the present invention involves attaching a drug that ionizes tube-forming metal to the inner surface of the metal tube, and then forming a liquid that undergoes a crosslinking reaction via the metal salt produced by the adhering drug. The method is characterized in that an ionomer is attached and the attached ionomer is adhered to the inner surface of the tube by the action of the adhering agent.

In other words, the inner surface of the metal tube is ionized, and the crosslinking of the liquid ionomer proceeds through the metal salt produced by the adhering agent. The metal salt can be solidified to provide a uniform layer of coating, and since the metal salt exhibits an adhesive function, the coating layer can be firmly adhered to the inner surface of the metal tube.

The means for obtaining the metal salt for crosslinking the ionomer simultaneously cleans the inner surface of the metal tube, making it possible to achieve highly uniform and strong coating treatment while omitting the pretreatment step as a whole.

[Brief explanation of the drawing]

The drawings show an embodiment of the method for coating the inner surface of a metal tube according to the present invention, and FIGS. 1A to 1C are explanatory views of the treatment steps,
FIG. 2 is a detailed view showing the state of the coating process. 1...metal tube, b...drug, c...liquid ionomer.

Claims (1)

[Claims] 1. A drug b that ionizes the tube-forming metal is attached to the inner surface of the metal tube 1, and then a liquid ionomer c that undergoes a crosslinking reaction via the metal salt generated by the adhering agent b is attached, and the adhering agent b A method for coating the inner surface of a metal tube, characterized in that the adhered ionomer c is adhered to the inner surface of the tube 1 by the action of: