JP7305327B2 - Electrofusion joint, piping structure, and method for manufacturing electrofusion joint - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrofusion joint, a piping structure, and a method for manufacturing an electrofusion joint.

2. Description of the Related Art Conventionally, when connecting synthetic resin gas pipes and water supply and sewerage pipes, there is known a technique of energizing and fusing an electrical fusion joint in which a heating wire is embedded.
When connecting pipes made of synthetic resin by fusion, conditions such as the optimum voltage and time for fusion (fusion conditions) differ depending on the properties of the resin, the diameter and thickness of the pipe, and the like.
The fusion conditions differ depending on the type of pipe or joint, and the electric fusion joint is attached with a fusion management tag on which information on the fusion conditions is recorded (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2009-92111

The bodies of pipes and joints are color coded according to their type.
However, joints are not necessarily colored in the same color as pipes for the same use, and it is desired to easily identify the use of the joint regardless of the color of the joint main body (main body portion).

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electric fusion joint, a piping structure, and a method for manufacturing an electric fusion joint that can easily identify the application of the joint.

In order to solve the above problems, the present invention has the following aspects.
[1] A body portion and an identification portion formed integrally with the body portion, wherein the identification portion has a color difference (ΔE) with the body portion of 1 or more, and based on the color of the identification portion An electrofusion joint that can identify the application of the joint by
[2] The electric fusion joint according to [1], wherein the body portion is formed in a tubular shape, and the identification portion is formed in a layered shape covering the inner peripheral surface of the body portion from the inside in the radial direction.
[3] The electric fusion joint according to [1], wherein a heating wire is embedded in the inner peripheral surface of the body portion, and the identification portion covers the heating wire.
[4] The electrofusion joint according to any one of [1] to [3], a cylindrical main body, and one or more identifiers integrally formed on the outer surface of the main body and extending in the pipe axis direction of the main body and a resin pipe comprising a layer, wherein a color difference (ΔE) between the identification portion and the identification layer is 10 or less.

[5] The method for manufacturing an electrofusion joint according to [2], comprising the steps of placing the identification portion in a resin molding die, and injecting a first resin onto the outer peripheral surface of the identification portion. and a step of molding the body portion.
[6] The method for manufacturing an electrofusion joint according to [3], wherein the heating wire coated with the identification part is wound around the core mold, and the heating wire is wound around the core mold. A method for manufacturing an electric fusion joint, comprising the steps of fitting a resin molding die with a gap from the resin molding die, and injecting a first resin into the resin molding die to mold the main body. .

The electrofusion joint of the present invention allows for easy identification of joint applications.

1 is a cross-sectional view showing an electrofusion joint according to one embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view showing an electrofusion joint according to another embodiment of the present invention; It is a fragmentary sectional view showing the piping structure concerning one embodiment of the present invention. It is the side view which looked at the piping structure of FIG. 3 from the direction of A. FIG.

[Electrofusion joint]
An electrofusion joint of the present invention comprises a joint body and an identification member attached to the outer surface of the joint body.
BEST MODE FOR CARRYING OUT THE INVENTION An electric fusion joint according to one embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1 , the electrofusion joint 1 of the present embodiment includes a main body portion 10 formed in a tubular shape and an identification portion 30 integrally formed with the main body portion 10 . The electric fusion joint 1 is a so-called socket formed in the shape of a straight pipe.
The identification portion 30 is formed in a layered shape covering the inner peripheral surface 10a of the main body portion 10 from the inside in the radial direction. An annular stopper 14 is formed on the inner peripheral surface of the identifying portion 30 near the center in the tube axis direction. The stopper 14 has a function of stopping the connected resin pipe.
The electric fusion joint 1 includes terminal cover portions 11, 11 projecting from the outer surface of the body portion 10, and terminals 12, 12 provided in the vicinity of the terminal cover portions 11, 11. As shown in FIG.
Openings 21 and 22 are formed at both ends of the main body 10 in the tube axis direction.

The electrofusion joint 1 includes a heating wire 13 such as a nichrome wire. The heating wire 13 is embedded in the inner peripheral surface 10 a of the body portion 10 of the electric fusion joint 1 . The heating wire 13 is formed so as to generate heat and melt the surrounding synthetic resin when energized.

The terminal cover portions 11, 11 are formed in a cylindrical shape integrally with the main body portion 10 in order to protect the metal terminals 12, 12 inside.
Since the outer diameters of the terminal cover portions 11, 11 are determined according to the connector (not shown) of the fusion splicer, they are constant regardless of the characteristics of the resin of the resin pipe to be connected, the diameter, the wall thickness, etc. is the size of

The terminals 12, 12 protected by the terminal cover portions 11, 11 are connected to the heating wire 13 embedded in the inner peripheral surface 10a of the body portion 10, and the terminals 12, 12 are connected to the connector of the fusion splicer. , and is formed so that the heating wire 13 can be energized.

The identification portion 30 is colored according to the application of the electric fusion joint 1 .
Applications of the electric fusion joint 1 include, for example, tap water, sewage, gas, plants, and rentals.
The electric fusion joint 1 differs in size, shape, withstand pressure, etc. according to its use, and is preferably connected to resin pipes used for the same use.
By matching the use of the electric fusion joint 1 and the use of the resin pipe, the electric fusion joint 1 and the resin pipe are joined more reliably, and leakage of fluid flowing through the resin pipe is suppressed. Cheap.

A color difference (ΔE) between the identification portion 30 and the main body portion 10 is 1 or more, preferably 5 or more, and more preferably 10 or more. When the color difference is equal to or greater than the above lower limit value, the operator can easily recognize the identification portion 30 during the fusing work. Although the upper limit of the color difference is not particularly limited, it is, for example, 100 or less, and preferably 80 or less in practice.
Color differences include color differences in the L*a*b* color system defined in JIS Z8781-4:2013.
The color difference can be measured using a spectral color difference meter (handy type spectral color difference meter "NF333" manufactured by Nippon Denshoku Industries Co., Ltd.), and is preferably measured in a darkened environment such as a dark room.
Here, the color difference (ΔE) is calculated by the following formula.
ΔE=√((L ₁ −L ₂ ) ² +(a ₁ −a ₂ ) ² +(b ₁ −b ₂ ) ² ) (1)
In equation (1), L ₁ , a ₁ , and b ₁ represent the brightness L, the chromaticity a in the red direction, and the chromaticity b in the yellow direction, respectively, and L ₂ , a ₂ , and b ₂ are They respectively represent the lightness L of the main body 10, the chromaticity a in the red direction, and the chromaticity b in the yellow direction.

Examples of the synthetic resin (first resin) forming the main body 10 include high-density polyethylene, medium-density polyethylene, crosslinked polyethylene, polypropylene, polyolefin resins such as polybutene, polyphenylene sulfide, polyethylene terephthalate, and vinyl chloride. mentioned.
From the viewpoints of moldability and cost, the first resin is preferably high-density polyethylene, medium-density polyethylene, or crosslinked polyethylene, and more preferably high-density polyethylene or medium-density polyethylene.
These first resins may be used alone or in combination of two or more.

The mass average molecular weight of the first resin is preferably 1.0×10 ² or more and 1.0×10 ⁶ or less, more preferably 1.5×10 ² or more and 3.0×10 ⁵ or less. When the mass average molecular weight is within the above numerical range, the main body 10 is likely to have desired physical properties as a joint.
The mass average molecular weight of the first resin is measured according to JIS K 7252-1.

The content of the first resin is preferably 90% by mass or more and 100% by mass or less with respect to the total mass of the body portion 10 . When the content of the first resin is within the above numerical range, the main body 10 is likely to have desired physical properties as a joint.

The main body 10 may contain various additives such as antioxidants, ultraviolet absorbers (UVA), light stabilizers, and pigments in addition to the first resin.

As the synthetic resin (second resin) forming the identification portion 30, the same resin as the first resin can be used. The second resin may be the same as or different from the first resin.

In addition to the second resin, the identification portion 30 preferably contains a coloring agent from the viewpoint of improving the distinguishability between the main body portion 10 and the identification portion 30 . As the coloring agent, pigments and dyes can be mentioned, and commercially available products can be used.
Examples of pigments include organic pigments such as azo, phthalocyanine, threne, and dye lake; inorganic pigments such as oxide, molybdenum chromate, sulfide-selenide, and ferrocyanide. be done.
The type and content of the coloring agent can be appropriately determined according to the color of the identification portion 30 . The color of the identification portion 30 can be appropriately determined according to the application of the electrofusion joint 1 .
For example, when the electrofusion joint 1 is used for clean water, the identification part 30 is preferably yellow or red, and when the electrofusion joint 1 is used for gas, the identification part 30 is preferably blue or black.
Since the identification portion 30 contains a coloring agent, the identification portion 30 can be colored according to the application of the electrofusion joint 1 . In addition, the application of the electric fusion joint 1 can be identified by the color of the identification portion 30 regardless of the color of the body portion 10 .

Next, a method for manufacturing the electrofusion joint 1 will be described.
The method of manufacturing the electric fusion joint 1 comprises a step of placing the identification portion 30 in a resin molding die (not shown), and injecting a first resin onto the outer peripheral surface of the identification portion 30 to form the body portion 10. and a step of molding.
First, the identifying portion 30 corresponding to the shape of the electric fusion joint 1 is molded as a preform (preforming step). In the present embodiment, it is preferable that the identification section 30 has a straight tubular shape.
Next, the identification part 30, which is a preform, is arranged in the resin mold (arrangement step). The heating wire 13 is spirally wound around the outer peripheral surface of the identification portion 30 (winding step).
Next, the main body 10 is formed by injecting the first resin onto the outer peripheral surface of the identification section 30 around which the heating wire 13 is helically wound (main body forming step).
By the above steps, the electric fusion joint 1 including the identifying portion 30 integrally formed in a layer covering the inner peripheral surface 10a of the body portion 10 from the inside in the radial direction is obtained.
In addition, you may perform a winding process before an arrangement|positioning process.

The electric fusion joint 1 includes an identification portion 30 having a color difference of 1 or more from the body portion 10 . The identifying portion 30 is colored to indicate the application of the electrofusion joint 1, so that the application of the joint can be easily identified regardless of the color of the body portion 10. FIG.
In addition, since the color difference between the identification portion 30 and the body portion 10 is 1 or more, the identification portion 30 can be easily visually recognized, and the application of the joint can be more easily identified.
Further, when the electric fusion joint 1 is viewed from the opening 21 or the opening 22, the identification part 30 is exposed at the opening end, so that the identification part 30 remains unchanged even after the electric fusion joint 1 and the resin pipe are connected. 30 colors are easily visible.
Further, in the electric fusion joint 1, the identification part 30 is integrally formed with the main body part 10, so the identification part 30 is separated from the main body part 10 compared to the fusion management tag of Patent Document 1. No fear.

Next, an electric fusion joint according to another embodiment of the present invention will be described.
In addition, in the constituent elements of the electric fusion joint 2 shown in FIG. 2, the same reference numerals are given to the same constituent elements as those of the electric fusion joint 1, and the explanation thereof is omitted.

As shown in FIG. 2 , the electric fusion joint 2 includes a tubular main body 10 and a heating wire 13 embedded in an inner peripheral surface 10 a of the main body 10 . The heating wire 13 is covered with an identification portion 32 . A portion of the identification portion 32 is exposed on the inner peripheral surface 10 a of the main body portion 10 . Note that the identification portion 32 may not be exposed from the body portion 10 , and in this case, the identification portion 32 may be visible through the inner peripheral surface of the body portion 10 . Transmission in this case is not limited to complete transmission. That is, the color of the identification portion 32 may be visible through the body portion 10 (so-called translucent state) while the colors of the identification portion 32 and the body portion 10 are mixed.

The color of the identification portion 32 is the same as the color of the identification portion 30 described above.
That is, the color difference (ΔE) between the identifying portion 32 and the main body portion 10 is 1 or more.
The identification portion 32 may be made of the second resin described above, or may be made of another material. Other materials include resin paints and the like.

Next, a method for manufacturing the electrofusion joint 2 will be described.
The method of manufacturing the electrofusion joint 2 includes winding the heating wire 13 covered by the identification portion 32 around a core mold (not shown), and opening a gap from the outside of the core mold around which the heating wire 13 is wound to perform resin molding. and a step of injecting a first resin into the resin molding mold to mold the body portion 10 .
First, the heating wire 13 is covered with the identifying portion 32 (covering step). The covering step may be performed by spraying the material forming the identifying portion 32 onto the heating wire 13 or by immersing the heating wire 13 in the material forming the identifying portion 32 .
Next, the heating wire 13 coated with the identification portion 32 is spirally wound around the core mold (winding step).
Next, a resin molding mold having a gate for injecting the first resin is fitted into the core mold around which the heating wire 13 is wound with a gap from the outside (fitting step).
Next, the first resin is injected into the inside of the resin molding die to mold the body portion 10 (body portion molding step).
Next, after the injection molding is completed, the mold for resin molding is removed.
Next, the core molds are separated from each other along the axial direction to remove the core molds from the injection molded body (core mold removing step).
Finally, the first resin injected into the gate is cut off from the injection molded body to obtain the electrofusion joint 2 .
Through the above steps, the heating wire 13 covered with the identification portion 32 is embedded in the inner peripheral surface 10a of the body portion 10, and the electric fusion joint 2 in which the body portion 10 and the identification portion 32 are integrally formed is obtained. .

The electric fusion joint 2 includes an identification portion 32 having a color difference of 1 or more from the main body portion 10 . The identification portion 32 is colored to indicate the application of the electrofusion joint 2, so that the application of the joint can be easily identified regardless of the color of the body portion 10. FIG.
In addition, since the color difference between the identification portion 32 and the body portion 10 is 1 or more, the identification portion 32 can be easily visually recognized, and the application of the joint can be more easily identified.
Furthermore, since the identification portion 32 can be formed with a smaller amount of material than the identification portion 30 described above, the cost can be reduced.

[Piping structure]
As shown in FIG. 3 , the piping structure S of this embodiment includes an electric fusion joint 1 and a resin pipe 40 inserted into an opening 22 of the electric fusion joint 1 .
3, illustration of the resin pipe inserted into the opening 21 is omitted.

The resin pipe 40 includes a cylindrical main body 41 and one or more identification layers 42 integrally formed on the outer surface of the main body 41 and extending in the pipe axial direction of the main body 41 .
The identification layer 42 is strip-shaped. As shown in FIG. 4, four identification layers 42 are annularly arranged at intervals of 90° around the tube axis of the main body 41 .
The outer diameter of the resin pipe 40 is substantially the same as the inner diameter of the opening 22 of the electric fusion joint 1 . The end portion of the resin pipe 40 is fitted to the stopper 14 of the electric fusion joint 1 and is fused and connected.

The resin pipe 40 is cylindrically formed of synthetic resin. As the synthetic resin (third resin) forming the resin pipe 40, the same resin as the synthetic resin (first resin) forming the body portion 10 described above can be used.
From the viewpoints of moldability and cost, the third resin is preferably high density polyethylene, medium density polyethylene or crosslinked polyethylene, more preferably high density polyethylene or medium density polyethylene.
These third resins may be used alone or in combination of two or more.

The mass average molecular weight of the third resin is preferably 1.0×10 ² or more and 1.0×10 ⁶ or less, more preferably 1.5×10 ² or more and 3.0×10 ⁵ or less. When the mass-average molecular weight is within the above numerical range, the main body 41 is likely to have desired physical properties as a pipe.
The weight average molecular weight of the third resin is measured by the same method as for the weight average molecular weight of the first resin.

The content of the third resin is preferably 90% by mass or more and 100% by mass or less with respect to the total mass of the main body 41 . When the content of the third resin is within the above numerical range, the main body 41 is likely to have desired physical properties as a resin pipe.

The main body 41 may contain various additives such as antioxidants, ultraviolet absorbers (UVA), light stabilizers, and pigments in addition to the third resin.

The color difference (ΔE) between the main body 41 and the identification layer 42 in the L*a*b* color system defined in JIS Z8781-4:2013 is preferably 1 or more, more preferably 5 or more, and furthermore 10 or more. preferable. When the color difference is equal to or greater than the lower limit value, it is easy to distinguish between the main body 41 and the identification layer 42 . Although the upper limit of the color difference is not particularly limited, it is, for example, 100 or less, and preferably 80 or less in practice.
The color difference in the resin pipe 40 can be measured by the same method as the color difference (ΔE) between the identification portion 30 and the main body portion 10 described above.
The color difference in the resin pipe 40 is calculated by Equation (1) described above.
In the resin pipe 40, L ₁ , a ₁ , and b ₁ in the formula (1) represent the lightness L of the main body 41, the red chromaticity a, and the yellow chromaticity b, respectively, and L ₂ and a ₂ , _b2 represent the lightness L, red chromaticity a, and yellow chromaticity b of the identification layer 42, respectively.

The lightness (L*) of the main body 41 or the identification layer 42 in the L*a*b* color system defined in JIS Z8781-4:2013 is preferably 20 or more. When the lightness (L*) of the main body 41 or the identification layer 42 is 20 or more, the main body 41 or the identification layer 42 is easily visible even in a dark place such as a pipe space where the resin pipe 40 is installed.

The resin (fourth resin) forming the identification layer 42 may be the same type of resin as the first resin, or may be a different type of resin. Also, the fourth resin may be the same type of resin as the second resin, or may be a different type of resin. Also, the fourth resin may be the same type of resin as the third resin, or may be a different type of resin. From the standpoint of difficulty in peeling the identification layer 42 from the outer surface of the main body 41, the fourth resin is preferably the same kind of resin as the third resin.
Examples of the fourth resin include resins similar to the third resin, preferably high-density polyethylene, medium-density polyethylene, or crosslinked polyethylene, more preferably high-density polyethylene or medium-density polyethylene.
The fourth resin may be used alone or in combination of two or more.

The weight average molecular weight of the fourth resin is similar to the weight average molecular weight of the third resin.

The content of the fourth resin is preferably 1.0×10 ⁻⁵ mass % or more and 10 mass % or less with respect to the total mass of the identification layer 42 . When the content of the fourth resin is within the above numerical range, the identification layer 42 is likely to have desired physical properties as a resin pipe.

From the viewpoint of improving weather resistance, the identification layer 42 preferably contains an antioxidant. Examples of antioxidants include phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, amine-based antioxidants, lactone-based antioxidants, and the like.

The content of the antioxidant is preferably 10 ppm (ppm is the mass standard; the same shall apply hereinafter) to 5000 ppm, more preferably 100 ppm to 2000 ppm, and more preferably 300 ppm to 1500 ppm with respect to the total mass of the identification layer 42. More preferred. When the content of the antioxidant is equal to or higher than the above lower limit value, the weather resistance of the identification layer 42 is likely to be improved. When the content of the antioxidant is equal to or less than the above upper limit, the balance with the content of other additives is excellent, and the physical properties of the identification layer 42 are likely to be improved.
Antioxidants may be used alone or in combination of two or more.

From the viewpoint of improving weather resistance, the identification layer 42 preferably contains an ultraviolet absorber (UVA). Examples of UV absorbers include benzophenone UV absorbers, salmalate UV absorbers, benzocoat UV absorbers, benzotriazole UV absorbers, cyanoacrylate UV absorbers, and quenchers.
Benzophenone-based UV absorbers and benzotriazole-based UV absorbers are particularly preferred as UV absorbers for polyethylene or polypropylene.
Benzophenone-based UV absorbers include 2-hydroxy-4-methoxy-benzophenone and the like.
Benzotriazole-based UV absorbers include 2-(2-hydroxy-5-methylphenyl)benzotriazole (Sumisorb200, manufactured by Sumika Chemtex Co., Ltd.), 2-(2-hydroxy-5-t-butyl-5- methylphenyl)-5-chlorobenzotriazole (Tinuvin326, manufactured by BASF), 2-(2-hydroxy-3,5-di-t-butylphenyl)-5-chlorobenzotriazole (Tinuvin327, manufactured by BASF), 2 -(2-Hydroxy-3,5-di-t-amylphenyl)benzotriazole (Tinuvin 328, manufactured by BASF) and the like.

The content of the ultraviolet absorber is preferably 10 ppm or more and 1000 ppm or less, more preferably 50 ppm or more and 800 ppm or less, and even more preferably 80 ppm or more and 400 ppm or less, relative to the total mass of the identification layer 42 . When the content of the ultraviolet absorber is equal to or higher than the above lower limit, the weather resistance of the identification layer 42 can be easily improved. When the content of the ultraviolet absorber is equal to or less than the above upper limit, the balance with the content of other additives is excellent, and the physical properties of the identification layer 42 are likely to be improved.
Ultraviolet absorbers may be used alone or in combination of two or more.

From the viewpoint of improving weather resistance, the identification layer 42 preferably contains a light stabilizer. Examples of light stabilizers include salicylate light stabilizers, benzophenone light stabilizers, benzotriazole light stabilizers, cyanoacrylate light stabilizers, hindered amine light stabilizers (HALS), and the like.
As the light stabilizer, a hindered amine light stabilizer is preferred.
Hindered amine light stabilizers include tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate (manufactured by ADEKA Co., Ltd., trade name: ADEKA STAB LA-52”), 2,2,6,6-tetramethyl-4-piperidyl methacrylate (manufactured by ADEKA Corporation, trade name “ADEKA STAB LA-87”), bis(2,2,6,6-tetramethyl -4-piperidyl) sebacate (manufactured by ADEKA Co., Ltd., trade name "ADEKA STAB LA-77Y", trade name "ADEKA STAB LA-77G") and the like.

The content of the light stabilizer is preferably 10 ppm or more and 1000 ppm or less, more preferably 50 ppm or more and 800 ppm or less, and even more preferably 80 ppm or more and 400 ppm or less, relative to the total mass of the identification layer 42 . When the content of the light stabilizer is equal to or higher than the above lower limit, the weather resistance of the identification layer 42 is likely to be improved. When the content of the light stabilizer is equal to or less than the above upper limit, the balance with the content of other additives is excellent, and the physical properties of the identification layer 42 are likely to be improved.
A light stabilizer may be used individually by 1 type, and may use 2 or more types together.

The identification layer 42 may contain carbon black from the viewpoint of improving weather resistance and improving the visibility of the resin pipe 40 . Examples of carbon black include furnace black, acetylene black, channel black and thermal black.
The content of carbon black is preferably 1000 ppm or more and 5.0×10 ⁵ ppm or less, more preferably 2000 ppm or more and 3.0×10 ⁵ ppm or less, and 20000 ppm or more and 1.0× 10 ⁵ ppm or less is more preferable. When the content of carbon black is at least the above lower limit, the weather resistance of the identification layer 42 is improved, and the distinguishability between the main body 41 and the identification layer 42 is easily improved. When the content of carbon black is equal to or less than the above upper limit, the balance with the content of other additives is excellent, and physical properties of the identification layer 42 are likely to be improved.
One type of carbon black may be used alone, or two or more types may be used in combination.

The identification layer 42 preferably contains a coloring agent from the viewpoint of improving the distinguishability between the main body 41 and the identification layer 42 . Examples of the coloring agent include those similar to those used in the identification section 30 described above.
The type and content of the coloring agent can be appropriately determined according to the color of the identification layer 42 . The color of the identification layer 42 can be appropriately determined according to the application of the electrofusion joint 1 .
For example, when the electrofusion joint 1 is used for clean water, the identification layer 42 is preferably yellow or red, and when the electrofusion joint 1 is used for gas, the identification layer 42 is preferably blue or black.
Since the identification layer 42 contains a coloring agent, the identification layer 42 can be colored according to the application of the electrofusion joint 1 . In addition, the application of the electrofusion joint 1 can be identified by the color of the identification layer 42 regardless of the color of the body portion 10 .

The content of the colorant is preferably 1 ppm or more and 25000 ppm or less with respect to the total mass of the identification layer 42 . When the content of the coloring agent is equal to or higher than the above lower limit value, the distinguishability between the main body 41 and the identification layer 42 is easily improved. When the content of the colorant is equal to or less than the above upper limit, the balance with the content of other additives is excellent, and physical properties of the identification layer 42 are likely to be improved.
The colorants may be used singly or in combination of two or more.

In the piping structure S, the color difference between the identification portion 30 integrally formed with the main body portion 10 and the identification layer 42 formed on the resin pipe 40 is preferably 10 or less, more preferably 5 or less, and further preferably 1 or less. preferable. When the color difference is less than the above upper limit, it is easy to recognize that the electric fusion joint 1 and the resin pipe 40 are used for the same purpose. As a result, erroneous connection between the electric fusion joint 1 and the resin pipe 40 can be easily suppressed, and poor connection between the electric fusion joint 1 and the resin pipe 40 can be reduced.
Further, it is preferable that the identification portion 30 and the identification layer 42 are colored in the same system according to the use of the piping structure S. Since the identification portion 30 and the identification layer 42 are colored in the same system, it is easy to recognize that the electric fusion joint 1 and the resin pipe 40 are used for the same purpose, and the above effects can be easily obtained. .

In the piping structure S, the resin pipe 40 is inserted into the opening 22 of the electric fusion joint 1, the heating wire 13 of the electric fusion joint 1 is energized to generate heat, and the synthetic resin around the heating wire 13 is melted. It is obtained by joining the identification part 30 and the resin pipe 40 by the above.
The fusion conditions for the electrical fusion joint 1 can be appropriately determined according to the size, type, application, and the like of the electrical fusion joint 1 .

A method of manufacturing the resin pipe 40 includes a step of forming the main body 41 and the identification layer 42 by co-extrusion molding.
As a manufacturing apparatus for the resin pipe 40, for example, a manufacturing apparatus including an extruder, a sizing die, a cooling tank, and a cutting machine can be exemplified. An extruder is a coextrusion capable former. The extruder has at least two feed ports. A sizing die is a cylindrical member whose diameter decreases as it goes downstream. The cooling bath is a device that cools the diameter-reduced resin pipe and hardens the resin. As the cooling bath, for example, a water-cooled cooling bath can be used.

An example of a method for manufacturing the resin pipe 40 using the manufacturing apparatus will be described.
A third resin and, if necessary, an additive (the third resin and the additive may be collectively referred to as a third resin composition) are introduced from one feed port of the extruder. A fourth resin and an additive (the fourth resin and the additive may be collectively referred to as a fourth resin composition) are introduced from another supply port of the extruder. The third resin composition is heated above the melting point of the third resin and kneaded. The fourth resin composition is heated above the melting point of the fourth resin and kneaded. Next, the third resin composition and the fourth resin composition are extruded into a cylinder by an extruder. The third resin composition and the fourth resin composition flow through separate channels and then join together, and the fourth resin composition forms the identification layer 42 .
As a result, a cylindrical molded body in which the identification layer 42 is integrally formed on the outer surface of the main body 41 is obtained.

Next, the cylindrical compact is inserted into a sizing die. The cylindrical molded body has a desired thickness as it passes through the sizing die. A cylindrical molded body adjusted to a desired thickness is inserted into a cooling bath. The cooling bath cools the cylindrical molded body and hardens the resin. The cured cylindrical molded body is cut to a desired length to form a resin pipe 40 .

The heating temperature of the third resin composition in the extruder is, for example, preferably 170° C. or higher and 250° C. or lower, more preferably 180° C. or higher and 220° C. or lower. When the heating temperature is within the above numerical range, good fluidity can be obtained while suppressing thermal decomposition of the third resin.
The heating temperature for the fourth resin composition in the extruder is the same as the heating temperature for the third resin composition.

The temperature of the cooling water in the cooling tank is preferably 20° C. or higher and 30° C. or lower, for example. If the temperature of the cooling water is within the above range, the cylindrical molded article can be sufficiently cured.

The inner diameter of the main body 41 of the resin pipe 40, the thickness of the main body 41, the thickness of the identification layer 42, the width of the identification layer 42, and the number of identification layers 42 depend on the size and shape of the die of the extruder and the sizing die. Adjustable.

As described above, in the piping structure S of the present embodiment, since the identification portion 30 and the identification layer 42 are colored in the same system, the application of the electric fusion joint 1 and the resin pipe 40 can be improved. are the same, erroneous connection between the electric fusion joint 1 and the resin pipe 40 can be suppressed, and poor connection between the electric fusion joint 1 and the resin pipe 40 can be reduced.
In the piping structure S, the combination of the colors of the identification layer 42, the body portion 10, and the identification portion 30 is, for example, red for the identification layer 42, black for the body portion 10, and red for the identification portion 30; The color of the identification layer 42 is green, the color of the body portion 10 is white, and the color of the identification portion 30 is green; the combination of the color of the identification layer 42 is gray, the color of the body portion 10 is black, and the color of the identification portion 30 is gray. is mentioned.

The piping structure S of this embodiment is formed by connecting the electric fusion joint 1 and the resin pipe 40 . However, the piping structure is not limited to this embodiment, and the electric fusion joint 2 may be employed instead of the electric fusion joint 1 .

The invention is not limited to the embodiments described above.
In the above-described embodiments, the shape of the electrofusion joints 1 and 2 are sockets. The present invention is not limited to this, and the shape of the electrofusion joint may be an elbow or a tee.
In the above-described embodiment, the identification layer 42 is formed on the resin pipe 40 . The present invention is not limited to this, and the resin pipe may not have the identification layer. In this case, it is preferable that the identifier and the main body of the resin pipe are colored in the same system.
In the above-described embodiment, the identification portion 30 is formed over the entire inner peripheral surface 10a of the body portion 10 . The present invention is not limited to this, and the identification portion may be formed on a part of the inner peripheral surface of the body portion.

Reference Signs List 1, 2 electric fusion joint 10 body portion 10a inner peripheral surface of body portion 11 terminal cover portion 12 terminal 13 heating wire 14 stopper 21, 22 opening 30, 32 identification portion 40 resin pipe 41 main body 42 identification layer S piping structure

Claims (5)

comprising a body portion and an identification portion integrally formed with the body portion,
The main body is formed in a tubular shape,
The identification portion is formed in a layered shape covering an inner peripheral surface of the main body portion from the inside in a radial direction,
The identification unit has a color difference (ΔE) of 1 or more in the L*a*b* color system defined in JIS Z8781-4:2013 with the main body,
An electrofusion joint, wherein the application of the joint can be identified based on the color of the identification portion. comprising a body portion and an identification portion integrally formed with the body portion,
A heating wire is embedded in the inner peripheral surface of the main body,
The identification unit covers the heating wire,
The identification unit has a color difference (ΔE) of 1 or more in the L*a*b* color system defined in JIS Z8781-4:2013 with the main body,
An electrofusion joint , wherein the application of the joint can be identified based on the color of the identification portion . The electrofusion joint according to claim 1 or 2 ;
A piping structure comprising a cylindrical main body and a resin pipe provided with one or more identification layers integrally formed on the outer surface of the main body and extending in the pipe axial direction of the main body,
A piping structure in which a color difference (ΔE) in the L*a*b* color system defined in JIS Z8781-4:2013 between the identification portion and the identification layer is 10 or less. A method for manufacturing an electrofusion joint according to claim 1 ,
A step of arranging the identification part in a resin molding mold;
A method of manufacturing an electric fusion joint, comprising: injecting a first resin onto the outer peripheral surface of the identification portion to mold the body portion. A method for manufacturing an electrofusion joint according to claim 2 ,
a step of winding the heating wire coated with the identification portion around a core mold, and fitting a resin molding mold with a gap from the outside of the core mold around which the heating wire is wound;
and injecting a first resin into the resin molding die to mold the main body.

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