JPH0914574A - Anti-corrosion protection method for propulsion pipe - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method capable of forming a high hardness anticorrosion protective layer on an outer peripheral surface of a propulsion pipe, particularly on a joint portion where the pipe ends are welded, in an extremely short time. [Structure] Joint portion A formed by welding the ends of the propulsion pipes 1 and 2
And arranging the mold 4, and injecting the reaction liquid containing the norbornene-based monomer, the metathesis catalyst, and the activator into the void B formed by the joint 4 and the mold 4, Is cured to form an anticorrosion protective layer that covers the joint portion A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosion protection method for a propulsion pipe, and more specifically, when welding the pipe ends of the propulsion pipe one after another at a construction site to proceed with the direct pushing propulsion work,
The present invention relates to a method for forming an anticorrosion protective layer having excellent anticorrosion performance and high hardness in an extremely short time over the joint portion of each propulsion pipe and the entire length of the propulsion pipe.

[0002]

2. Description of the Related Art Recently, a direct push propulsion method has been adopted as a method of burying piping across a road or the like. This construction method has an advantage that it is not necessary to cut off road traffic at the time of construction because the pipe can be buried in a state of crossing the road without excavating the road from the ground surface.

This direct thrusting method is generally performed as follows. That is, hard holes are dug at appropriate places on both sides of the road, and from one vertical hole to the other vertical hole, a pipe of a predetermined length is sequentially pushed directly into the ground by, for example, a jack to cross the road. . At this time, the pipes to be sequentially pushed into the soil are welded to each other in the vertical holes in one vertical hole. At the end of the construction, one long pipe was buried in the ground crossing the road.

[0004] By the way, in the pipes used, the outer surface of a metal pipe such as a steel pipe is usually covered with an anticorrosion protective layer of a desired thickness made of a resin such as polyethylene or polyurethane, leaving about 150 mm of the pipe end portion. The outer surface of the uncoated pipe end is anticorrosive. When carrying out propulsion work using such pipes, first remove the anticorrosion coating on the pipe ends and bare the surface of the metal pipe, then abut the pipe ends of the pipes Weld to a weld. Therefore, in the joint portion of each pipe, there is a welded portion and a bare exposed surface portion that is barely exposed to both sides of the welded portion with a desired length.

Therefore, it is necessary to immediately form an anticorrosion protective layer for the joint portion so as to cover the outer peripheral surface of the joint portion, and to perform anticorrosion protection treatment on the joint portion. In that case, the anticorrosion protective layer after formation is directly pushed into the ground and violently rubs against the sand and gravel in the ground to be worn away, and may be peeled from the joint portion. It is required to be made of a material that is large and that is not easily damaged by the above-mentioned friction. Generally, the hardness of the anticorrosion coating layer in the propulsion pipe is required to be 60 or more in Shore hardness D. It is preferably 70 or more. Also,
It is an important property required for the anticorrosion protection layer that it can be formed quickly at the construction site and thus contributes to shortening the time of the propulsion work.

By the way, in the propulsion work, when the anticorrosion protective layer is formed on the outer peripheral surface of the above-mentioned propulsion pipe joint, the outer peripheral surface of the joint is covered with, for example, a mold having a split structure, A method is employed in which a liquid reactive resin is injected into a void formed between the mold and the outer peripheral surface, and the reactive resin is cured to form an anticorrosion protective layer. For example, the curing reaction is completed within 0.5 to 1 hour 2
A method is known in which a liquid-mixing type urethane-based resin is press-fitted into the cavity of the above-mentioned mold to cure.

However, when this urethane resin is used, it takes more time to fully cure and develop the final strength, and the flexural modulus of the anticorrosion protective layer after completely curing is 1800 to 9000 kg / As low as cm ² . Also, in the case of this two-liquid type urethane resin, the viscosity when press-fitting is 5
Since it is as high as about 00 to 1500 cps, the pressure at the time of press fitting also increases accordingly, and the pressure applied to the mold and the joint portion becomes as high as 10 to 40 kg / cm ² . Therefore, when arranging the mold on the outer peripheral surface of the propulsion pipe, it must be arranged so that liquid leakage does not occur between the two, which is a work that requires a considerably high degree of skill. Moreover, every time the joint portion is subjected to the anticorrosion protection treatment, the above-mentioned work of arranging the mold, which requires skill, must be performed, which is not a preferable construction method for on-site work that requires quickness and simplicity.

Moreover, the thickness of the anticorrosion protective layer formed is 10
When it is considerably thicker than 0 mm, when the high-viscosity urethane resin as described above is press-fitted, air is often entrained in the mold, and the air is present as a void in the formed anticorrosion protective layer, and the quality is improved. It is easy to cause defects. When the urethane resin is cast to form an anticorrosion protective layer, in order to completely cure it, it is usually press-molded into a mold and then heated to be subjected to a post-curing treatment. In the end, the time required to complete the entire anticorrosion protection treatment also becomes long, and the effect is short in terms of speed.

Further, as to the anticorrosion protection treatment in the propulsion work, for example, the method disclosed in Japanese Patent Publication No. 7-6595 is known. In the case of the method disclosed herein, a polyethylene or polyurethane anticorrosion layer is provided as a first layer by coating the outer peripheral surface of the joint portion, and further, a polyester in which glass fibers or metal fibers are mixed is further provided. Or a second protective layer of epoxy acrylate resin
It is provided as a layer for anticorrosion protection. In particular, the examples disclose a method of forming the first layer with a polyethylene heat shrink tube or sheet.

[0010]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 7-6
In the method disclosed in Japanese Laid-Open Patent Publication No. 595, the following measures have been proposed in Examples regarding the formation of the protective layer in order to shorten the time required for propulsion work.
First, the first treatment is to add a catalyst for accelerating the curing reaction to polyester or epoxy acrylate. However, since this treatment greatly affects the progress of the curing reaction of the resin depending on the temperature of the construction site and the temperature of the piping, workability is poor, and the quality of the formed protective layer is difficult to be uniform, which makes it difficult to perform the work in the field. There are many disadvantages to adoption.

Another procedure is to form a first layer of polyethylene heat shrink tubing or sheet and then form a second layer with the first layer having a residual heat of 40 ° C. or higher. It is a thing. However, in this procedure, the starting point of work for forming the second layer is limited by the residual heat state of the first layer. Therefore, this procedure lacks flexibility in field work. For example, when the first layer is formed, the first layer immediately begins to cool to ambient temperature, so the work for forming the second layer is started before the first layer has a residual heat of 40 ° C or higher. Must. Therefore, in an actual field work, if the work is to be carried out quickly, it is necessary to take measures such as forming the first layer with a heat-generating material or heating the pipe itself, and
When forming the layer, it is necessary to preheat the first layer.

When this treatment is applied, according to FIG. 7 of the above-mentioned prior art, the gelling time of the second layer is about 15 minutes when the temperature of the first layer is 40 ° C., and It takes 20 minutes or more to develop the strength that enables propulsion work.
However, these times are long for propulsion work. Furthermore, in this treatment, since the second layer is formed before the heat dissipation and cooling of the first layer are completed, the inside of the layer is in a heat storage state, and the viscosity of the polyethylene of the first layer is low, The shear strength in the pipe axis direction between the pipe and the outermost second layer is extremely low. Therefore, when the propulsion work is performed in this state, the second layer may be displaced in the tube axis direction. Therefore, in the end, the second
Even after the formation of the layer, it is necessary to leave it until the first layer is completely cooled, and the time required for the anticorrosion protection treatment as a whole must be long.

The present invention solves the above-mentioned problems in protection against corrosion of a propulsion pipe joint represented by Japanese Patent Publication No. 7-6595, and provides the propulsion pipe joint and the entire length of the propulsion pipe. An object of the present invention is to provide an anticorrosion protection method for a propulsion pipe capable of forming a high hardness anticorrosion protection layer in an extremely short time.

[0014]

In order to achieve the above-mentioned object, in the present invention, a die is arranged so as to cover the outer peripheral surface of the propulsion pipe, and the outer peripheral surface of the propulsion pipe and the metal mold are arranged. After injecting a reaction solution containing a norbornene-based monomer, a metathesis catalyst, and an activator into the cavity formed by the mold, the reaction solution is cured to form an anticorrosion protective layer that covers the outer peripheral surface. A featured anti-corrosion protection method for a push-push tube is provided.

In particular, in the present invention, a propulsion pipe capable of forming an anticorrosion protective layer having high hardness and excellent anticorrosion performance in a joint portion formed by welding the pipe ends of the propulsion pipe in an extremely short time. An anticorrosion protection method is provided. The case of applying the method of the present invention to the joint portion of the propulsion pipe will be described in detail below.

As shown in the partial sectional view of FIG. 1, the surface portion 1a of the propulsion pipe 1 is removed by removing the anticorrosion coating (not shown) on the end of the propulsion pipe 1 which has already been propelled in the soil G. Of the propulsion pipe 2 to be welded is removed to expose the surface portion 2a of the propulsion pipe, and the pipe ends of the propulsion pipes are butted against each other. Weld.

Therefore, the welded portion 3 and the bare exposed surface portions 1a and 2a located on both sides of the welded portion 3 are formed in the joint portion A of the propulsion pipes 1 and 2 after the welding is completed. Next, as shown in FIG. 2, the mold 4 is placed so as to cover the outer peripheral surface of the connecting portion A. As shown in FIG. 3, the mold 4 has a cylindrical shape as a whole so that it can be divided into two in the radial direction. The upper mold and the lower mold have bolts 5a and nuts. It can be tightened with 5b. An injection port 4a for injecting a reaction solution described later is attached to one mold (the mold located on the lower side), and an air hole 4b is formed on the other mold (the mold located on the upper side). The total length of the mold 4 is longer than the length of the joint portion A shown in FIG. 1, and both end portions 4c and 4d thereof can press-contact the coating layer 1b of the propulsion pipe 1 and the coating layer 2b of the propulsion pipe 2, respectively. The mold surfaces 4e and 4f near both ends 4c and 4d are tapered surfaces.

Therefore, when the mold 4 is arranged outside the joint A, both ends 4 of the mold 4 in the longitudinal direction inside the mold 4 are arranged.
A void portion B is formed between c and 4d so as to surround the coating layers 1b and 2b and the joint portion A. Prior to disposing the mold 4, the outer peripheral surface of the joint A is subjected to a surface treatment of about SIS St-3 using, for example, a disk sander, and the surfaces of the coating layers 1b and 2b are After removing dust, water, oil, etc. with a dry cloth and a suitable solvent, roughening with sandpaper with a grain size of 30 to 120 improves the adhesion with the anticorrosion coating layer formed there. Is suitable. Known primer treatment, acid treatment, heat treatment and the like may be performed depending on the situation.

In this state, the reaction liquid is injected into the cavity B from the injection port 4a of the mold 4. The reaction liquid used in the method of the present invention contains a norbornene-based monomer, a metathesis catalyst, an activator, and, if necessary, an optional component described below, and the norbornene-based monomer is ring-opened. It causes bulk polymerization. That is, in order to prevent bulk polymerization of the norbornene-based monomer with only one liquid, the above-mentioned components are divided into two or more liquids to prepare a reaction stock solution, and these are prepared immediately before injection into the mold. Each reaction stock solution is mixed.

The reaction solution has a low viscosity of about 300 cps immediately after mixing the reaction stock solution, and is very fluid. Therefore, when injecting the reaction liquid into the void B of the mold 4, it is not necessary to apply a large pressure to the reaction liquid, and the reaction liquid is promptly injected in every corner of the void B with the start of the injection work. It is injected into a uniform state without entraining air.

When it is heated to a temperature of about 60 ° C., it is rapidly exothermicly cured and solidified within 5 minutes.
Since the process of this curing reaction is ring-opening polymerization, no decomposition gas is generated, and the mechanical strength characteristics such as compression hardness, elongation, flexural modulus, etc. begin to develop reliably from the initial stage of the curing reaction. The value of 50% or more of the final characteristic value is reached within about 10 minutes after the initiation of the curing reaction.

Here, as the norbornene-based monomer,
It may be anything as long as it has a norbornene ring, for example, a bicyclic compound such as norbornene or norbornadiene; a tricyclic compound such as dicyclopentadiene or dihydrodicyclopentadiene; a tetracyclododecene such as tetracyclododecene. Tetracycles; pentacycles such as tricyclopentadiene; heptcycles such as tetracyclopentadiene; alkyls such as methyl, ethyl, propyl, butyl, alkenyls such as vinyl, alkylidene such as ethylidene, phenyl. , Tolyl, naphthyl and the like substituted with an aryl; further, a substituent having a polar group such as an ester group, an ether group, a cyano group and a halogen atom.

These monomers may be used alone or in a suitable mixture of two or more kinds.
Among these, tricyclic, tetracyclic or pentacyclic are preferred because they are easily available, have excellent reactivity, and have excellent heat resistance of the cured product after the reaction. You can The norbornene-based monomer is ring-opening polymerized to be resinified and solidified. At this time, the ring-opening polymer to be formed is preferably thermosetting. For that purpose, 10% by weight or more, preferably 30% by weight or more, of the norbornene-based monomer to be used may be a crosslinkable monomer. This crosslinkable monomer has a reactivity of 2
A polycyclic norbornene-based monomer having two or more heavy bonds in one molecule, specifically, dicyclopentadiene,
Examples thereof include tricyclopentadiene and tetracyclopentadiene.

The metathesis catalyst is a catalyst for promoting the ring-opening polymerization of the norbornene-based monomer, and the kind thereof is not particularly limited, and metathesis is carried out to cause the ring-opening polymerization of the norbornene-based monomer. Any material may be used, and examples thereof include halides such as tungsten, molybdenum and tantalum, oxyhalides, oxides and ammonium salts.

The amount of the metathesis catalyst used is usually set to 0.01 to 50 mmol, preferably 0.1 to 20 mmol, per 1 mol of the norbornene-based monomer in the reaction solution used. If this amount is too small, the activity for ring-opening polymerization of the norbornene-based monomer is too low and it takes a lot of time for ring-opening polymerization, so that curing in the mold does not proceed rapidly, and However, if the amount used is too large, ring-opening polymerization will proceed rapidly, and the reaction solution will cure in the process of being injected into the cavity of the mold, or the metathesis catalyst will precipitate and the reaction solution will be in a homogeneous state. It becomes difficult to save.

An activator capable of enhancing the catalytic activity of the metathesis catalyst is further added to such a reaction solution. Any activator may be used as long as it can activate the metathesis catalyst, and examples thereof include alkylaluminum, alkylaluminum halides, alkoxyalkylaluminum halides, aryloxyalkylaluminum halides and organic tin compounds. .

The amount of the activator used is not particularly limited, but it is usually the metathesis catalyst 1 in the reaction solution.
It is set to 1 to 10 moles per mole. This is because if the amount used is too small or too large, the same disadvantages as in the case of the metathesis catalyst occur. Furthermore,
Other optional components such as known antioxidants, fillers, pigments, colorants, foaming agents, flame retardants, and solid lubricants such as graphite may be added to the reaction liquid.

Further, polybutadiene, styrene-butadiene copolymer, styrene-butadiene-is added to this reaction solution.
When a diene elastomer such as a styrene copolymer or a styrene-isoprene-styrene copolymer, natural rubber, polyisoprene, or ethylene-propylene-diene terpolymer is blended, the impact resistance of the obtained cured product is improved. Therefore, it is preferable. When the diene-based elastomer is blended, the blending amount is set to 15% by weight or less, preferably 10% by weight or less, based on the weight of the norbornene-based monomer in the reaction solution. This is because if the blending amount becomes too large, the reaction liquid becomes highly viscous and it becomes difficult to inject it into the mold, and the heat resistance and rigidity of the cured product will start to decrease. As described above, the reaction solution composed of the above components is prepared by dividing the reaction solution into two or more solutions so that the ring-opening polymerization reaction of the norbornene-based monomer does not occur with only one solution. Every time, it is mixed immediately before the injection work into the mold, and at that time, the ring-opening polymerization reaction of the norbornene-based monomer occurs and the curing reaction proceeds.

For example, a reaction stock solution A composed of a norbornene-based monomer, a metathesis catalyst, and other optional components, and a reaction stock solution B composed of a norbornene-based monomer, an activator, and other optional components, are each alone. Does not cause a curing reaction. However, when the reaction stock solution A and the reaction stock solution B are mixed,
At that time, a component necessary for the ring-opening polymerization reaction, that is,
The reaction liquid in which all of the norbornene-based monomer, the metathesis catalyst, and the active material are prepared becomes the ring-opening polymerization reaction of the norbornene-based monomer. In the present invention, the reaction stock solution is mixed to form a reaction solution, which is immediately poured into the cavity of the mold to be cured.

Usually, a mixing head of a reaction injection molding machine is attached to the injection port of a mold, and two or more kinds of the above-mentioned reaction stock solutions are simultaneously injected into the mixing head to cause collision and mixing to form a reaction solution. It is prepared and poured into the cavity of the mold as it is. Since the method of the present invention is applied at the construction site, considering the workability, it is preferable to prepare the reaction solution using two types of reaction stock solutions, but the reaction is performed using three or more types of reaction stock solutions. A liquid may be prepared.

In this case, since the norbornene-based monomer and the respective components are sufficiently mixed with each other after the reaction stock solutions are mixed, and the ring-opening polymerization proceeds, the reaction stock solutions before mixing are
In both cases, it is preferable to contain a norbornene-based monomer. However, when the norbornene-based monomer, the metathesis catalyst, and the activator are contained in the reaction stock solution before mixing, ring-opening polymerization of the norbornene-based monomer starts before mixing, and therefore, normally, The metathesis catalyst and the activator do not coexist in one reaction stock solution.

The viscosity of the reaction stock solution to be used is not particularly limited, but if the viscosity is too high or too low, it becomes difficult to mix the reaction stock solutions and inject it into the mold. Is usually 50 to 2000 cps, preferably 100
It is set within the range of 1000 cps. When the reaction solution prepared by mixing the above-mentioned reaction stock solution is injected into the cavity B of the mold 5 shown in FIG. 2, the ring-opening polymerization reaction of the norbornene-based monomer proceeds in the cavity B and the injection is performed. The reaction liquid becomes a cured product.

Before the injection of the reaction solution, the sheet heating element is attached to the outer surface or the inner surface of the die 4 or the heating element is embedded in the thick portion of the die 4 to mold the sheet with the sheet heating element. If the inner surface of 4 is preheated to a temperature of 60 ° C., for example, the injected reaction solution will generate heat by proceeding with the curing reaction from the portion in contact with the mold 4, and the heat generated at that time will also add to the injected reaction solution. It is preferable because it can be rapidly hardened to the inside.

Further, in the method of the present invention, prior to disposing the mold on the outer side of the joint portion, the following treatment may be applied to the joint portion to further enhance the anticorrosion protection effect, which is preferable. is there. For example, in the joint portion, a thermoplastic rubber-based urethane containing ethylene-vinyl acetate copolymer-based, polyamide-based, styrene-isoprene block copolymer (SIS), styrene-butadiene block copolymer (SBS), etc. When a sheet or tape of hot-melt adhesive such as thermosetting resin such as resin, modified polyolefin, and water-soluble polyvinyl alcohol, polyol, etc. is wound and a cured layer of the above-mentioned reaction liquid is formed thereon, the reaction occurs. The heat generated during the curing reaction of the liquid softens these hot melt adhesives and firmly adheres them to the joint, and also firmly adheres to the inner surface of the formed hardened layer, which results in the axial direction of the pipe generated during propulsion work. A very excellent resistance force against the shear stress of is developed.

Further, conventional anti-corrosion paints such as butyl rubber type, asphalt type, mixed type thereof, tar epoxy resin type, epoxy resin type, urethane resin type, acrylic resin type, lead type rust inhibitor, etc. are jointed. It is also suitable for improving the anticorrosion property when applied to the area. Furthermore, as in the conventional case, even if a heat shrinkable tube or sheet layer is formed as an anticorrosion layer on the joint portion and the above-mentioned cured layer of the reaction solution is formed as a protective layer on it, an excellent anticorrosion protective effect is obtained. Is obtained.

When the curing reaction of the reaction liquid in the mold 4 is completed, the mold 4 is removed, and as shown in FIG. 4, the joint A and the coating layers 1b and 2b are covered, and both ends are covered. On the outer surface of the portion, an anticorrosion protective layer 6 having a tapered surface of a shape in which the tapered surface of the mold 4 is transferred is formed. The anticorrosion protection layer 6 has a high hardness and is less worn during propulsion. Further, the anticorrosion protective layer 6 is formed only by injecting the reaction liquid into the mold, and is formed within 5 minutes at most after the start of the work, which is very suitable for field work.

The above description is for the case where the outer peripheral surface of the propulsion pipe joint portion is subjected to anticorrosion protection treatment, but the method of the present invention is not limited to this, and the plastic coated pipe produced in the factory is not limited thereto. The tube after being applied over the entire length of the coating layer may be used as a propulsion tube as it is, or if the tube obtained by applying it over the entire length of the outer peripheral surface of a metal tube such as a steel tube is used as it is. It can be used as a propulsion tube.

In this case, the anticorrosion protective layer of the present invention can be formed in an extremely short time even if the entire length of the target tube is long, so that the molds can be sequentially coated from one end to the other end. Even if the operation of arrangement-injection of reaction solution-demolding is promoted, the time required for the whole construction is not so long.

[0039]

Example An anticorrosion protective layer was formed on the joint of a polyethylene-coated steel pipe as follows. Steel pipe with an outer diameter of 300 mm, which is coated with a polyethylene coating layer with a thickness of about 3 mm 1.
After removing the anticorrosion coating (not shown) on the pipe end of No. 2, the pipe ends were butted and welded (Fig. 1).

On the other hand, 75 parts by weight of dicyclopentadiene and 25 parts by weight of asymmetric cyclopentadiene trimer were mixed,
Here, 5 parts by weight of a styrene-isoprene-styrene block copolymer (trade name, Kraton 1170, manufactured by Ciel) and 2 parts by weight of a phenolic antioxidant (trade name, Irganox 1010, manufactured by Ciba Geigy) are dissolved. , The obtained solution is divided into two liquids, one of which is
A reaction stock solution A was prepared by mixing 40 mmol of diethylaluminum chloride (activator), 44 mmol of n-propanol, and 20 mmol of silicon tetrachloride per liter, and the other solution contained tri (tridecyl). Ammonium molybdate (metathesis catalyst) 10
A reaction stock solution B was prepared by adding millimoles. Both reaction stock solutions A and B were allowed to stand by at a temperature of 30 ° C.

SIS with a disc sander on the surface of the joint A
A base treatment of about St-3 is applied, and the coating layers 1b and 2
After roughening the surface of b with sandpaper with a grain size of about 80, the outside diameter of both ends 4c and 4d is 3 outside the joint A.
18mm, inner diameter of central part is 330mm, total length is 550m
At m, a metal mold 4 having a two-divided structure in which a planar heating element was embedded in a thick portion immediately below the mold surface was placed (FIG. 2).

Therefore, the thickness of the void B in the mold 4 is, for example, about 5 mm between the exposed surface portions 1a and 2a. Then, adjust the temperature of the inner surface of the mold 4 to 60 ° C,
The same volumes of the above-mentioned reaction stock solution A and reaction stock solution B were mixed using a reaction injection molding machine to obtain a reaction solution, which was immediately injected into the cavity B from the injection port 4a of the mold 4.

After the start of the injection, the internal surface temperature of the mold 4 changes with time, the surface temperatures of the coating layers 1b and 2b change with time, and the temperature of the central portion in the thickness direction of the reaction solution injected into the void B changes with time. Was measured respectively. The results are shown in FIG. In the figure, curve I is the curve of the mold inner surface temperature over time.
II represents the time variation of the coating layer surface temperature, and curve III represents the time variation of the central temperature of the reaction solution.

As is apparent from FIG. 5, the injected reaction solution first initiates a curing reaction at the portion in contact with the inner surface of the mold at a temperature of 60 ° C., and heat generation at that time rapidly induces the internal curing reaction. Finally, the curing reaction is completed and solidified in about 5 minutes. The mold was removed 10 minutes after the injection of the reaction solution. The anticorrosion protective layer 6 as shown in FIG. 4 was formed on the outer side of the joint portion.

This anticorrosion protective layer is JISK under constant temperature.
Shore hardness (TYPE-D) was measured according to 7215. The value was 80. This hardness is a value that can sufficiently withstand wear during propulsion. When the flexural modulus of the anticorrosion protective layer at a temperature of 23 ° C. was measured, the value was in the range of 17,000 to 19000 kg / cm ² . The Shore hardness of the formed anticorrosion protective layer was measured at various temperatures. FIG. 6 shows the result.

As is clear from FIG. 6, in the case of this anticorrosion protective layer, the hardness was not significantly decreased up to the measurement temperature of 100 ° C.,
Considering together with the results shown in FIG. 5, it can be seen that the target hardness characteristics are exhibited in the initial stage after the start of injection of the reaction liquid. Also, as is clear from FIG.
Since the surface temperature of the coating layers 1b and 2b rises to a temperature of about 140 ° C. in the initial stage (about 2 minutes after the start of the reaction), when the coating layer is made of polyethylene, for example, the surface temperature is sufficiently higher than its softening point. Has become. Therefore, the formed anticorrosion protective layer and the coating layer are heat-sealed, and together with the effect of the roughening treatment, very excellent peeling resistance and tear resistance are exhibited between the two layers. This is suitable for propulsion work.

For comparison, an epoxy resin (trade name, Epicoat 801, Epicure 3220, manufactured by Yuka Shell Co., Ltd.) and a polyurethane resin (trade name, Polyway AR-).
100 m, manufactured by San Techno Chemical Co., Ltd., thickness 5 m
m anticorrosion coating layer was formed. In the case of an epoxy resin, a reaction time of 40 minutes is required until the Shore hardness D of the anticorrosion coating layer reaches 60, and in the case of a polyurethane resin, it takes 60 minutes or more before the Shore hardness D reaches 60. I needed time.

As described above, the method of the present invention makes it possible to form a highly hard anticorrosion coating layer on the joint portion in an extremely short time, and is useful as a novel anticorrosion protection treatment in propulsion work. Next, for comparison, on the outer peripheral surface of the joint portion, a shrink tube made of a hot-melt adhesive having an inner layer made of ethylene-vinyl acetate copolymer as a main component and an outer layer made of heat-shrinkable polyethylene is used as an anticorrosion protective layer. (Thickness 2 mm)
Was formed.

With respect to the anticorrosion protective layer of Examples and the above Comparative Examples,
The following durability test was conducted. That is, as shown in FIG. 7, the hydraulic cylinder 7 is attached to one of the pipes 2 of the connecting pipe body in which the anticorrosion protection layer 6 is formed in the joint portion so that the anticorrosion coating layer 6 is located at the center. After setting the connection pipe body in the soil tank 8 and fixing it, 60% of the gravel-grade soil is placed in the soil tank.
The following soil 9 was filled around the connecting pipe body without any gap.

Then, a pressure of about 1.2 kg / cm ² is applied from above the soil 9 with the jack 10, and the hydraulic cylinder 7 is operated in that state to slide the connecting pipe body at a sliding speed of about 20 cm / min. The sliding length of 100m was promoted. After the test, the connection tube was taken out, the appearance was examined, and the anticorrosion protective layer 6 was covered with a compress to measure the insulation resistance. The results are shown in Table 1.

[0051]

[Table 1]

[0052]

As is apparent from the above description, in the present invention, a reaction liquid containing a norbornene-based monomer, a metathesis catalyst and an activator is used as the material of the anticorrosion protective layer formed in the joint portion of the propulsion pipe. Since the anticorrosion protective layer is used, the time required for forming the anticorrosion protective layer is extremely short, and the anticorrosion protective layer has a high hardness, and wear during propulsion is reduced. That is, the method of the present invention is extremely useful when applied in the field work in propulsion work.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a state in which propulsion pipes are welded to each other at their pipe ends.

FIG. 2 is a partial cross-sectional view showing a state in which a mold is arranged outside the joint section in FIG.

FIG. 3 is a side view of the mold used in FIG.

FIG. 4 is a partial cross-sectional view showing a state in which a corrosion protection layer is formed on the joint portion of the propulsion pipe.

FIG. 5 is a graph showing the time change of the temperature at each position in the mold when the reaction liquid is injected into the mold in the example.

FIG. 6 is a graph showing the temperature dependence of the Shore hardness D of the formed anticorrosion protective layer.

FIG. 7 is a schematic view showing a method for testing durability of an anticorrosion protective layer.

[Explanation of symbols]

 1, 2 Propulsion pipes 1a, 2a Bare surface 1b, 2b of the propulsion pipes 1, 2b Coating layer 3 Welded part 4 Mold 4a Injection port 4b Air holes 4c, 4d Both ends of mold 4 4e, 4f Mold 4 Taper part of inner surface of 5a Bolt 5b Nut 6 Anticorrosion protection layer 7 Hydraulic cylinder 8 Soil tank 9 Soil 10 Jack A Joint part of propulsion pipe B Void

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Ohama Inventor Hiroyuki Ohama 2-1, Konandai, Konan-ku, Kanagawa Prefecture Kamome housing complex No. 10 Building 604 (72) Inventor Toru Morita 2-6-1, Marunouchi Chiyoda-ku, Tokyo Within Kawakawa Electric Co., Ltd. (72) Inventor Tetsuo Kadoma 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Kazuo Toho 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Date Inside the ZEON Corporation (72) Inventor Makoto Yamamoto 1-2-1 Yokou, Kawasaki-ku, Kanagawa Prefecture Kanagawa Japan Zeon Corporation R & D Center (72) Inventor Hirotoshi Tanimoto 1-2-2 Yokou, Kawasaki-ku, Kanagawa Prefecture No. 1 in the General Development Center of Zeon Corporation

Claims (2)

[Claims] 1. A mold is disposed so as to cover the outer peripheral surface of the propulsion tube, and a norbornene-based monomer, a metathesis catalyst, and a void are formed between the outer peripheral surface of the propulsion tube and the mold. An anticorrosion protection method for a propulsion pipe, which comprises injecting a reaction solution containing an activator and then curing the reaction solution to form an anticorrosion protective layer covering the outer peripheral surface. 2. The anticorrosion protection method for a propulsion pipe according to claim 1, wherein the outer peripheral surface is a peripheral surface of a joint portion formed by welding pipe ends of the propulsion pipe.