JP4203351B2 - Coating structure of pipe inner wall and its construction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite coating structure on the inner wall of a pipe and a construction method for forming the same.
[0002]
[Prior art]
Various pipes used for water supply, drainage or liquid distribution in buildings, condominiums, plants, and steel pipes used for steel towers or structures of structures are shipped with their inner walls painted for the purpose of rust prevention. There are many cases.
[0003]
Currently, there are many buildings and condominiums in the country that have been over 15 to 20 years old, and their drainage pipes are aging, and there is a need for renovation and refurbishment. Conventionally, repair and refurbishment methods for aging drainage pipes were mainly excavation and replacement work, but the construction period is long, the materials and expenses are large, and the new aging is low-cost and low-cost construction. There is a need for a method for correcting drainage pipes. In large industrial facilities such as oil plants and power plants, there are many buried pipes deep underground and pipe structures that are high above the ground. Under the current situation where scrap and build cannot be easily performed, extending the life of these old pipes is a major technical issue for the Japanese heavy industry.
[0004]
As this correction method, pipe polishing / coating method has been attracting attention, and various pigs (shape, configuration or transfer method thereof) have been proposed. If it is possible to repaint the inner wall of the drainage pipe using such a paint pig, it will be possible to re-use it as it is without excavating or replacing the aging drainage pipe, providing short-term and low-cost construction, The inconvenience of line stoppage can be minimized. In addition, sewer pipes and drain pipes have also started to be used as optical fiber laying paths due to the revision of the law, and their correction and reuse are attracting attention.
[0005]
Conventionally, as a method of painting inside a pipe, a rope is attached to a sponge lump that is approximately the same size (diameter) as the inside diameter of the pipe, and this is impregnated with a paint for coating and inserted into the pipe. The method of painting by dragging the rope and sliding the sponge lump along the inner wall surface of the pipe, or instead of attaching the rope to the sponge lump, the sponge lump impregnated with the paint for coating is inserted into the pipe, A method of coating by applying pressure from the rear and sliding the sponge lump along the inner wall surface of the pipe is known.
[0006]
However, in the case of the rope pulling method, the inner wall surface may be scraped or crushed due to the friction between the rope and the inner wall surface. The pipe may be cracked, cracked or holed, and the compressed air may be sprayed with the paint from the gap to the outside of the pipe, contaminating the surroundings. If the material is extremely damaged or thinned due to corrosion or the like, the part cannot withstand the applied pressure and may explode.
[0007]
As a method for solving the problems of the conventional construction method, the present inventor has developed a decompression (suction) pig construction method (Patent Document 1, Patent Document 2, Patent Document 3, etc.). The vacuum pig method is a method of inserting a sponge lump or a spherical body (collectively referred to as a vacuum pig) into the pipe and reducing the pressure inside the pipe from the end of the pipe to move the vacuum pig inside the pipe. Cleaning and painting. In the case of painting, a vacuum pig impregnated with paint is inserted and moved in the pipe for painting, or the paint is put in front of the pipe in the traveling direction of the vacuum pig and then the vacuum pig is inserted, and the ink at the time of screen printing is The coating is performed in the same manner as when the paint is pushed out by the rear decompression pig, in the same manner as it is pushed out and printed by the rear squeegee.
[0008]
In this decompression pig construction method, the degree of decompression used is about -0.1 to 0.5 atm. Using a general medium-sized vacuum vehicle (suction capacity 40 m ³ ), construction pipe diameter of 800 mmφ and pipe length of 1000 m The inner wall of the pipe can be painted, and the pressure differential damage to the old pipe is small and the work can be safely done because it does not explode outside.
[0009]
The development of the vacuum suction pig painting technology has enabled safe and simple painting of the inner walls of pipes, and the life of recycled old pipes can be extended. Technical requirements don't stop there. This is a requirement for further performance addition to the piping function, such as prevention of bad odors and unpleasant odors from old piping, and addition of acid resistance and alkali resistance, in other words, a requirement for highly functional pipe inner wall coatings.
[0010]
For example, in order to prevent the generation of malodors and unpleasant odors, it is conceivable to use antiseptic paints and antibacterial paints containing antiseptic additives and bactericides, as is generally known. According to the document, the effect was temporary and not sufficient in the closed pipe inner wall.
[0011]
[Patent Document 1]
JP 2000-51787 A [Patent Document 2]
JP 2001-259558 A [Patent Document 3]
JP 2002-186898 A
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a coating film that can meet the demand for higher function of the inner wall coating film by a simple technique.
[0013]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventor has eagerly investigated the special demand of pipe inner wall coating and the demand for advanced functionality, and as a result, has a coating structure having a specific composite structure in which functional fillers are arranged on the surface layer. Has been found to be extremely effective, and the present invention has been completed.
[0014]
That is, the present invention is a coating structure on the inner wall of a pipe having a functional filler surface layer on the inner wall of the pipe, and the coating film structure is constructed by forming a functional filler by using a swirling airflow, or a puff pig in the pipe. Is a method of forming a functional filler surface layer by introducing.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the composite coating film structure and the construction method found by the present inventors will be described in detail.
[0016]
The present invention utilizes the vacuum suction force and the pig coating method, which are the features of the vacuum suction pig coating technology developed by the present inventors so far, and basically is a wet state (semi-cured state) immediately after painting the inner wall of the pipe. ) Coating film is used as an installation base, and a functional filler (powder) is installed thereon to form a composite coating film structure.
[0017]
The construction method of the present invention is similar to the “Makiji method”, a traditional Japanese lacquer craft technique in which gold and silver powder is scattered and fixed on a semi-cured lacquer surface to express crafts.
[0018]
The manufacturing process of the composite coating film structure of this invention is demonstrated based on the conceptual diagram of FIG. Actually, a composite coating film structure is formed on the inner wall of the cylindrical pipe. In FIG. 1, the formation principle will be described using a flat plate.
[0019]
As shown in FIG. 1, for a pipe (base) made of metal or the like, first, a coating for the purpose of protecting the inner wall base of the pipe is applied to form a coating film base. Next, a surface layer is formed by providing a functional filler on the semi-cured coating film. In the present invention, when the functional filler is localized and becomes a surface layer, the effect is sufficiently exhibited.
[0020]
If necessary, a top coat can be further applied on the surface layer made of the functional filler.
[0021]
In addition, if it is not necessary to apply paint to the inner wall of the pipe, apply adhesive (or adhesive) instead of paint to the inner wall of the pipe, and use it as a base for installation, and install a functional filler on it. Such an embodiment is also included in the scope of the present invention.
[0022]
Furthermore, after applying a coating for the purpose of protecting the inner wall of the pipe to form a coating film base and curing it once (in this case, it is difficult to install and attach the functional filler as it is) A three-layer structure in which an adhesive is applied to fix and hold, and then a functional filler is provided on the adhesive layer to form a surface layer is also a preferred embodiment of the present invention.
[0023]
The painting of the inner wall of the pipe has been conventionally performed for the purpose of reinforcing the rust prevention and the strength deterioration due to aging for the purpose of extending the life of the aging pipe. In addition, antiseptic paints and antibacterial paints containing antiseptic additives and bactericides may be applied to suppress spoilage in the drain pipe, but the effect is temporary. This is due to the fact that antiseptic additives and antibacterial agents are uniformly dispersed and mixed in the coating film and delocalized, and some of the antiseptic additives and antibacterial agents blended in the inner wall surface layer where the effects are expected to appear. However, the effect is only borne by some of these antiseptic additives and antibacterial agents. The antiseptic additives and antibacterial agents in the coating film are included in the resin components necessary for coating film formation. It has been found that there is a drawback that it does not contribute to the manifestation of the effect.
[0024]
That is, as shown in FIG. 2, in the general functional coating film in which the functional filler is in a uniformly dispersed state (delocalized) in the coating film, the functional filler is surrounded by the coating resin component. If the functional filler is an antibacterial agent or a charge transfer redox catalyst that expresses its function by contact with the target substance, it is difficult to express the function by direct contact because it is distributed inside the coating film. Functional expression is achieved only by permeating the resin component inside and exuding it, and its effect is low. In particular, it can be seen that the solution of malodor and unpleasant odor does not function unless the solution method is provided on the inner surface of the drainage pipe. On the other hand, in the present invention, the functional filler is localized on the surface of the composite coating film, and the manifestation of the effect is extremely remarkable.
[0025]
In addition, many offensive odors and unpleasant odors are caused by bacteria and fungi that live in the piping. If scale deposits, sludge deposits, or insoluble fibers such as hair stick to the inner wall of the pipe, it may become a breeding bed for bacteria and fungi in the pipe, and the antiseptic paint or antibacterial paint may not be effective. In the present invention, by using fine powder as the functional filler, there is an advantage that the surface of the inner wall of the pipe can be made into a fractal surface state and these sticking can be physically prevented.
[0026]
Furthermore, when antiseptic paint or antibacterial paint is applied to the inner wall of a horizontal cylindrical pipe, the paint applied to the upper part of the inner wall starts to drip to the lower part along the inner wall side immediately after the paint is applied. After the paint is dried or cured, the thickness of the coating on the upper part of the inner wall is smaller than that of the lower part, and the coating thickness on the inner wall of the pipe is not uniform. In antiseptic paints and antibacterial paints, where preservatives and antibacterial agents leak out from the paint film, the function of the upper part of the inner wall is easily lost because the paint film on the upper part of the inner wall is thin. . On the other hand, since the functional filler of the present invention is in the form of powder, it does not sag and is evenly distributed and attached to the upper part of the inner wall to form a uniform functional inner wall surface layer, and the effect thereof is also the inner wall surface layer. And uniform.
[0027]
As the pipe coating material used in the present invention, an undiluted solvent-free coating material is usually used. This is because, in the case of a solvent-type paint in which the solvent is volatilized from the applied paint film, the atmosphere in the pipe is immediately saturated with the solvent vapor, which is extremely dangerous when there is a fire. . Therefore, a two-pack type epoxy paint that is generally known as an undiluted solvent-free paint, particularly a heavy anticorrosion paint, and is generally used well as a paint for pipe coating, is easy to handle. preferable. However, it is natural that the present invention is not limited to this.
The coating thickness is preferably about 0.1 to 3 mm, and preferably 0.2 to 1 mm. When the coating thickness is thin, the protection of the piping substrate is insufficient, and the functional surface layer to be installed is not sufficiently retained. If it is too thick, it becomes prominent in the case of horizontal piping painting, but the coating material is applied from the upper wall to the lower wall portion through the side wall within the curing time when the coating material is applied to the inner wall of the pipe to form a cured coating film. As a result, the coating film thickness in the upper wall portion is thin and the coating film thickness in the lower wall portion is thick, resulting in a non-uniform coating film in the pipe. When this non-uniform coating film becomes the foundation of the functional surface layer, the retention of the functional filler is also non-uniform, combined with a reduction in the protection and anti-corrosion power of the base steel pipe in the thin coating area, reducing the functionality and piping life. May be shorter.
[0028]
Also, the adhesive used in the present invention is not particularly limited, and if the inner wall of the pipe is not painted, select one that has good adhesion to the pipe substrate, and if the inner wall of the pipe is already painted Those having good adhesion to the coating film may be selected and used.
[0029]
Further, the functional filler used in the present invention has a function of imparting various functions to the coating film, and specific shapes include a lump shape, a spherical shape, a fiber shape, a flake shape, a needle shape, and the like. However, it is generally sufficient that it is in the form of a powder, and the shape, particle size, etc. are not particularly limited. Those having a diameter of about 5 to 500 μm are used.
[0030]
Various functions include, for example, heat insulating properties, heat transfer properties, antibacterial properties, antifouling properties, deodorizing properties, deodorizing properties, chemical resistance (acid resistance, alkali resistance), soundproofing properties, silencing properties, vibration control, and lubricity. Abrasion resistance, conductivity, etc. are mentioned, and those having at least one of these properties are preferred.
[0031]
More specific functional fillers include various inorganic hollow fine particles for the purpose of heat insulation, similarly carborundum, chondrite, etc. for heat transfer, and various inorganic antibacterial agents for antibacterial properties. In addition, various inorganic catalysts (charge transfer type oxidation-reduction catalyst), etc. for antifouling, deodorizing and deodorizing properties, colloidal silica, zeolite, etc. for acid resistance, colloidal silica, dolomite, etc. for alkali resistance, PTFE (perfluoroethylene polymer) powder is used for general chemical resistance, pearlite, vermiculite, pumice, etc. are used for soundproofing, silencing and vibration control, and lubricity and wear resistance are used. Molybdenum disulfide, carborundum, etc., stainless steel powder, aluminum leaf, etc. are used for conductivity. However, it is natural that the present invention is not limited to these.
[0032]
Although it is the surface layer thickness of the functional filler, it varies depending on the purpose of the functionality to be imparted, the tube diameter and shape, the state of the inner wall of the tube and the shape and size of the functional filler used, but usually 0.01 to 1.0 mm, preferably 0.05 to 0.5 mm. When the functional surface layer thickness is thin, the functional performance duration is short due to wear and peeling during use, and when it is too thick, the filler holding power of the coating film base becomes weak, and part of the filler surface layer is agglomerated. It may collapse.
[0033]
In the present invention, there is no particular limitation on the method of forming the surface layer by setting and attaching the functional filler to the adhesive layer under the surface layer that fixes and holds the semi-cured coating film surface or the surface layer, and the functional filler is not particularly limited. Any method may be used as long as it can be installed and adhered evenly to the substrate, but from the viewpoint of efficiency and the like, the swirling airflow installation method and the puff pig installation method described below are preferable.
[0034]
When the pipe is sucked under reduced pressure or when a pressurized gas is introduced, the gas flows in the pipe as an air current. An airflow in which this flow swirls the inner wall of the pipe is called a swirling airflow. The diameter and shape of the tube used, the pipe inner wall state, the air velocity, etc. are related to the generation of the swirling airflow. However, when the gas in the tube moves at a speed of 0.5 m / sec or more, the swirling airflow is appear. The swirling air flow installation method is a method of forming a functional surface layer by placing a functional filler on the swirling air flow and swirling the inside of the pipe so that the functional filler is installed and adhered evenly on the inner wall of the pipe inner wall. The air velocity suitable for the swirling air flow installation method varies depending on the diameter and shape of the tube, the state of the inner wall of the tube and the gas used, the shape and size of the functional filler used, the specific gravity, etc., but is usually 0.5 to 20 m / sec. It is preferably 1 to 10 m / sec. When the air flow velocity is too slow, a swirling air flow is hardly generated in the pipe, and when it is too fast, the functional filler installed and attached to the inner wall of the pipe may be peeled off by the subsequent air flow.
[0035]
Next, puff pigs are made by covering the pig surface with fine fibers with long bristle legs or porous sponges, and adding (covering) functional fillers to the pipe inner walls to lay the fillers. Is. The development hint is obtained from the female white powder puff makeup, and the name is also called “puff pig”. A method of introducing a puff pig coated with a functional filler into a pipe, sucking the inside of the pipe under reduced pressure, and moving the pipe so as to puff the inner wall of the pipe is called a puff pig installation method.
[0036]
The amount of installation / attachment of the functional filler to the base is not particularly limited, and may be an amount that covers almost the entire surface of the base, but may of course be less.
[0037]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1: Formation of heat-insulating composite coating film After mixing the main component and curing agent of a two-component solventless epoxy paint with a working life of 1.5 hours, the inner wall of a steel pipe cylindrical pipe having an inner diameter of 105 mm and a length of 1000 mm Immediate coating was performed to obtain a film thickness of 0.5 mm. The coating method is to introduce 300g of the epoxy paint and a 104mm diameter paint pig from the inlet of the pipe, attach a vacuum suction pump to the outlet of the pipe, and reduce the vacuum so that the moving speed of the paint pig is 1000mm / sec. The force was adjusted (see coating principle in FIG. 3).
[0038]
One hour after mixing the main component of the epoxy coating and the curing agent was 30 minutes after painting the inner wall of the pipe, and the coating film was in a semi-cured state before being dry to the touch.
[0039]
The suction force of the vacuum suction pump at the outlet of the pipe was adjusted so that the air velocity at the center of the pipe was 2 m / sec from the inlet of the pipe, and the generation of a swirling air flow was confirmed in the pipe. The swirling airflow was stably generated at an airflow velocity of 2 m / second or more. From the pipe inlet, as a functional filler, 30 g of glass inorganic hollow microparticles with an outer diameter of 100 μm having a single cavity with a diameter of 50 μm inside the sphere are put in a swirling airflow and placed on the semi-cured coating on the inner wall of the pipe A composite coating film having a surface layer composed of inorganic hollow fine particles was formed. The average thickness of the surface layer was 200 μm.
[0040]
After leaving at room temperature for 3 days, the thermal insulation of the composite coating was measured. For measurement, install a heat diffusion medium that uniformly diffuses heat on the heat source heater, and set the surface layer of inorganic hollow fine particles in close contact with the medium, and measure the temperature of the material steel plate. It went by.
Comparative Example 1
In the same manner as in Example 1, the inner wall of the pipe was painted with an epoxy paint. Then, without forming the surface layer with the functional filler, the epoxy paint coating film was allowed to stand for 3 days to make a pipe inner wall consisting only of the underlying epoxy coating film, not a composite coating film having no surface layer. Thereafter, in the same manner as in Example 1, the heat insulating property of the epoxy coating film was measured.
[0041]
The result combined with the heat insulating property of the material steel pipe is shown in FIG. From this result, it was found that the surface layer made of inorganic hollow fine particles showed heat insulation.
Example 2
A pipe inner wall having a composite coating film was prepared in the same manner as in Example 1 except that silica gel containing an antiseptic (average particle size 30 μm) was used as the functional filler instead of the glass inorganic hollow fine particles. This pipe was connected to a household drain pipe and used as a household drain pipe for 3 months. Thereafter, the drain pipe was taken out and the inner wall of the pipe was observed, but there was no solid matter, no finger touch and no odor.
Comparative Example 2
The paint used in Example 1 was mixed with 30 g of the preservative-containing silica gel used in Example 2 to obtain an epoxy paint. A pipe inner wall was made in the same manner as in Comparative Example 1 except that this paint was used. In the same manner as in Example 2, it was connected to a household drain pipe and taken out after 3 months. Although there was no fixed matter on the inner wall of the pipe, there was a finger touch and a slight odor was observed.
[0042]
From this, it was found that the silica gel containing a preservative has a greater effect as a preservative when localized as a surface layer of a composite coating film than when it is delocalized uniformly in the coating film. .
[Brief description of the drawings]
FIG. 1 is a process diagram schematically showing the production principle of a composite coating film structure according to the present invention.
FIG. 2 is a schematic view illustrating a comparison between a general functional coating film in which a functional filler is uniformly dispersed in a coating film and a composite coating film structure according to the present invention.
FIG. 3 is a schematic diagram showing the principle of painting the inside of a pipe with a painting pig.
4 is a graph comparing the heat insulating properties of a raw steel plate, a heat insulating composite coating film of Example 1, and an epoxy coating film of Comparative Example 1. FIG.

Claims (8)

A coating structure of a pipe inner wall having a composite structure comprising a surface layer composed of a functional filler and a coating film base for protecting the inner surface of the pipe inner wall or an adhesive layer under the surface layer for fixing and holding the surface layer. A coating structure on the inner wall of a pipe having a composite structure consisting of a surface layer made of a functional filler, an adhesive layer under the surface layer that fixes and holds the surface layer, and a coating film base under the adhesive layer for the purpose of protecting the inner wall surface of the pipe . Functional filler is heat insulation, heat transfer, antibacterial, antifouling, deodorant, deodorant, chemical resistance, soundproof, silencer, vibration control, lubricity, wear resistance, conductivity The coating structure of the inner wall of the pipe according to claim 1 or 2, wherein the coating film structure has at least one characteristic. The coating is applied to the inner wall of the pipe by a vacuum suction pig method to form a coating film base for the purpose of protecting the inner wall of the pipe, and then a functional filler is provided on the coating film to form a surface layer. Method of coating film construction on the inner wall of piping. By applying paint to the inner wall of the pipe using the vacuum suction pig method, a coating film base for the purpose of protecting the inner wall of the inner wall of the pipe is formed, then an adhesive layer is formed, and a functional filler is installed on the adhesive layer. The coating film construction method for the inner wall of the pipe, which consists of forming a surface layer. The method according to claim 4 or 5, wherein the surface layer is formed by generating a swirling air flow in the pipe and setting a functional filler on the coating film base or the adhesive layer. The method according to claim 6, wherein the swirling airflow in the pipe is generated by moving the gas in the pipe at a speed of 0.5 m / second or more. The method according to claim 4 or 5, wherein the surface layer is formed by introducing a puff pig containing a functional filler into the pipe and coating the functional filler from the puff pig onto the coating film base or the adhesive layer.

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