JP2005256934A - Electric fusion joint and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain an electric fusion joint being formed by providing gasoline resistance and its manufacturing method, capable of easily connecting a polyethylene multilayer tube having a barrier layer of an ethylene-vinyl alcohol copolymer in the middle so as to obtain gasoline resistance. <P>SOLUTION: This electric fusion joint 11 is provided with a heating wire 12 embedded in a joint inner tube portion 13 comprising polyethylene resin so as to respectively fuse polyethylene resin on the outer-periphery surface at an end part of the multiple layer tube to be joined and polyethylene resin on an inner-periphery surface of a receiving port of the electric fusion joint so that they are jointed. The barrier layer 14 of an ethylene-vinyl alcohol copolymer is provided on the outer periphery of the joint inner tube portion 13. A joint outer tube 15 comprising polyethylene resin is provided on the outer periphery of the barrier layer 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to an electric fusion joint and a method for producing the same, and more specifically, a barrier layer made of an ethylene-vinyl alcohol copolymer is added to a polyethylene resin in order to add barrier properties against gasoline, light oil, kerosene, and various organic solvents. The present invention relates to an electric fusion welded joint for connecting a multilayer pipe provided between an outer pipe and an inner pipe, and a method for manufacturing the same.

As a synthetic resin pipe used for gasoline transportation, a multilayer pipe made of polyamide and an ethylene-vinyl alcohol copolymer has been proposed (for example, see Patent Document 1). The multilayer pipe for transporting gasoline is mainly used as a piping material for connecting an automobile tank and an engine. Therefore, little consideration is given to the connection between the multilayer tubes.
JP 2003-21276 A

  However, in the case of pipes used for gasoline transportation at a gas station, it is necessary to connect the pipes at the bent or branched parts of the pipes. It is necessary to use a pipe joint that can be connected. For example, it is desirable to use a pipe joint such as an electric fusion joint for connecting a polyethylene pipe often used for a water pipe or a gas pipe.

  On the other hand, by providing a barrier layer made of an ethylene-vinyl alcohol copolymer having excellent gasoline resistance between an outer tube and an inner tube made of polyethylene resin, it is possible to impart gasoline resistance to the polyethylene tube. It has been broken.

  Therefore, the present invention can easily connect a polyethylene multilayer tube having a barrier layer made of an ethylene-vinyl alcohol copolymer in the middle to obtain gasoline resistance, and the joint itself has a barrier property against gasoline or the like. It is an object of the present invention to provide a given electric fusion joint and a manufacturing method thereof.

  In order to achieve the above object, an electric fusion joint of the present invention is an electric machine for connecting a multilayer pipe provided with a barrier layer made of an ethylene-vinyl alcohol copolymer between an outer pipe and an inner pipe made of polyethylene resin. A fusion joint for melting and joining the polyethylene resin on the outer peripheral surface of the end of the multilayer pipe and the polyethylene resin on the inner peripheral surface of the electrofusion joint to the inner pipe part made of polyethylene resin. And a barrier layer made of an ethylene-vinyl alcohol copolymer is provided on the outer periphery of the joint inner pipe portion, and a joint outer pipe portion made of polyethylene resin is provided on the outer periphery of the barrier layer. It is said.

  In addition, the method for producing an electric fusion joint according to the present invention includes electric fusion for connecting a multilayer pipe provided with a barrier layer made of an ethylene-vinyl alcohol copolymer between an outer pipe made of polyethylene resin and an inner pipe. A method for manufacturing a joint, wherein the first configuration includes a step of injection molding polyethylene resin to form a joint inner pipe portion, and a step of winding a heating wire around the outer peripheral surface of the joint inner pipe portion after molding. , A step of injection-molding or inserting an ethylene-vinyl alcohol copolymer on the outer periphery of the inner pipe part of the joint after the heating wire is wound, and a polyethylene resin is injection-molded on the outer periphery of the barrier layer after the molding. And a step of forming a joint outer pipe portion.

  Furthermore, the second configuration of the method for manufacturing an electric fusion joint according to the present invention includes a step of winding a polyethylene-coated heating wire around the outer periphery of the injection molding core, and disposing the injection molding core in a mold. A step of forming a joint inner pipe portion in which a heating wire is embedded by injection molding polyethylene resin, and an injection molding or insertion of an ethylene-vinyl alcohol copolymer on the outer periphery of the joint inner pipe portion after molding A step of forming a layer and a step of forming a joint outer pipe portion by injection-molding polyethylene resin on the outer periphery of the barrier layer after forming.

  ADVANTAGE OF THE INVENTION According to this invention, the polyethylene multilayer pipe | tube provided in the middle with the barrier layer which consists of an ethylene-vinyl alcohol copolymer can be easily connected by the same operation | work as a general polyethylene pipe for water supplies or gas. Moreover, since the barrier layer which consists of an ethylene-vinyl alcohol copolymer is provided also in the joint, sufficient barrier property with respect to gasoline etc. can be provided also to the joint itself.

  FIG. 1 is a sectional front view for explaining each process of manufacturing an electrofusion joint according to a first embodiment of the present invention. FIG. 2 shows a process for manufacturing an electrofusion joint according to a second embodiment of the present invention. FIG. 3 is a cross-sectional side view showing an example of a multilayer pipe connected by the electric fusion joint of the present invention, and FIGS. 4 and 5 are electric fusion joints shown in the second embodiment. FIG. 4 is a cross-sectional front view of the main part showing a state before the end of the multilayer pipe is inserted into the receptacle of the electric fusion joint, and FIG. It is a cross-sectional front view of the principal part which shows the state which inserted the edge part of the multilayer pipe into the receptacle of the fusion joint.

  First, as shown in FIG. 1 (D), an electrofusion joint 11 shown in the first embodiment includes a joint inner pipe portion 13 made of polyethylene resin in which a heating wire 12 is embedded, and an outer periphery of the joint inner pipe portion 13. A multilayer pipe structure having a barrier layer 14 made of an ethylene-vinyl alcohol copolymer and a joint outer pipe portion 15 made of polyethylene resin provided on the outer periphery of the barrier layer 14.

  The basic structure, shape, etc. of the electric fusion joint 11 can be the same as those of a polyethylene resin electric fusion joint for water and gas, depending on the size of the pipe (multilayer pipe) to be connected. For example, when the size is 100, it is only necessary to have a receiving port of about 114 mm. As the heating wire 12, a heating wire having a wire diameter of about 0.5 to 1.0 mm that has been conventionally used can be used.

  As shown in FIG. 1A, first, the electrofusion joint 11 is manufactured by injection-molding a polyethylene resin to form a bobbin that becomes the joint inner pipe portion 13 of the electrofusion joint 11. Next, as shown in FIG. 1 (B), the heating wire 12 is wound around a predetermined position on the outer peripheral surface of the joint inner pipe portion 13. Next, as shown in FIG. 1C, the barrier layer 14 is formed by injection-molding or insert-molding an ethylene-vinyl alcohol copolymer on the outer periphery of the joint inner pipe portion 13 around which the heating wire 12 is wound. Finally, a polyethylene resin is injection-molded on the outer periphery of the barrier layer 14 to form the joint outer pipe portion 15. Simultaneously with the injection molding of the joint outer pipe portion 15, both ends of the heating wire 12 are connected to the connector 16, respectively, and indicator pins 17 are formed in the vicinity of the connector 16, respectively. The fusion joint 11 is formed.

  When manufacturing the electric fusion joint 11 by such a manufacturing process, the thickness of the heating wire winding part in the said joint inner pipe part 13 is the polyethylene resin of the joint inner pipe part 13 by heat_generation | fever of the heating wire 12 at the time of a multilayer pipe | tube connection. The thickness of the outer peripheral surface of the multilayer pipe is set to a thickness that can be melted and joined, and depending on the size of the electrofusion joint 11, usually 1.0 to 2.0 mm is appropriate.

  Moreover, as shown in FIG. 2 (D), the electrofusion joint 21 shown in the second embodiment of FIG. 2 includes a joint inner pipe portion 23 made of polyethylene resin in which a heating wire 22 is embedded, and the joint inner pipe portion. A multi-layer pipe structure having a barrier layer 24 made of an ethylene-vinyl alcohol copolymer provided on the outer periphery of 23 and a joint outer pipe portion 25 made of polyethylene resin provided on the outer periphery of the barrier layer 24; The basic configuration is the same as that of the electric fusion joint 11 shown in the first embodiment.

  In the manufacture of the electric fusion joint 21, first, as shown in FIG. 2A, a polyethylene-coated heating wire 32 that is the source of the heating wire 22 is wound around the outer periphery of the injection molding core 31. The polyethylene-coated heating wire 32 does not need to be special, and the same one used for a conventional water-fusion or gas-made polyethylene resin electrofusion joint can be used.

  Next, the core 31 around which the polyethylene-coated heating wire 32 is wound is placed in a predetermined mold, and a polyethylene resin is injection-molded to embed the heating wire 22 as shown in FIG. The inner pipe portion 23 is formed. At this time, the polyethylene coating of the polyethylene-coated heating wire 32 is integrated with the injection-molded polyethylene resin by being melted by heat at the time of injection molding of the polyethylene resin, and the heating wire 22 is embedded in the joint inner pipe portion 23. It will be in the state.

  Further, as shown in FIG. 2C, the barrier layer 24 is formed by injection-molding or insert-molding an ethylene-vinyl alcohol copolymer on the outer periphery of the joint inner pipe portion 23 in which the heating wire 22 is embedded. Finally, a polyethylene resin is injection molded on the outer periphery of the barrier layer 24 to form the joint outer tube portion 25. Simultaneously with the injection molding of the joint outer pipe portion 25, both ends of the heating wire 22 are respectively connected to the connectors 26, and indicator pins 27 are formed in the vicinity of the connectors 26, respectively. The fusion joint 21 is formed.

  As shown in FIG. 3, a multilayer pipe 41 for transporting gasoline, which is a connection target of the electric fusion joints 11 and 21 shown in both the above-described embodiments, includes an inner pipe 42 made of polyethylene resin and ethylene-vinyl in order from the inside. It has a three-layer structure in which a barrier layer 43 made of an alcohol copolymer and an outer tube 44 made of polyethylene resin are laminated. The overall dimensions of the multilayer pipe 41 can be set in the same way as for polyethylene resin pipes for water and gas. For example, when the size is 100, the outer diameter is set to 114 mm and the wall thickness is set to 10 mm. That's fine.

  The polyethylene resin used in the electric fusion joints 11 and 21 and the multilayer pipe 41 may be the same as the polyethylene resin used for ordinary water or gas polyethylene pipes, for example, high-density polyethylene. . Further, the balance of the thicknesses of the joint inner pipe parts 13, 23 and the joint outer pipe parts 15, 25 and the balance of the thicknesses of the inner pipe 42 and the outer pipe 44 can be arbitrarily set according to manufacturability and the like. It is. Further, the surfaces of the electric fusion joints 11 and 21 and the multilayer pipe 41 can be colored to indicate that they are gasoline-resistant pipes.

  The ethylene-vinyl alcohol copolymer constituting the barrier layers 14, 24, 43 is an ethylene-vinyl alcohol copolymer or a mixture mainly composed of an ethylene-vinyl alcohol copolymer, and the ethylene-vinyl alcohol copolymer. As the above, those having an ethylene content of 35 to 70 mol% and a saponification degree of 95 mol% or more can be used. If the ethylene content is less than 35 mol%, a problem may occur in the moldability. If the ethylene content exceeds 70 mol%, the moldability is improved, but the barrier property is lowered and the desired gasoline resistance cannot be obtained. Moreover, even if the degree of saponification is less than 95 mol%, the barrier property is lowered, which is not preferable. The thickness of the barrier layers 14, 24, and 43 may be any thickness as long as sufficient barrier properties, particularly gasoline resistance, can be obtained. Usually, 100 to 300 μm is appropriate. Sex is hardly improved.

  Furthermore, conventionally used various additives can be mixed with the polyethylene resin or ethylene-vinyl alcohol copolymer. Moreover, an adhesive layer can be interposed between the respective layers as required. As this adhesive layer, any adhesive can be used as long as it can adhere a polyethylene resin and an ethylene-vinyl alcohol copolymer. For example, an adhesive resin composed of maleic anhydride and grafted polyolefin. Can be used. A thickness of about 100 μm is sufficient for the adhesive layer.

  For example, when connecting the multi-layer pipe 41 using the electric fusion joint 21, first, as shown in FIG. 4, an end face of the end of the multi-layer pipe 41 is scraped to remove the oxide film. Expose. Next, as shown in FIG. 5, the end portion (joint portion) of the multilayer pipe 41 after scraping is inserted into the receptacle of the electric fusion joint 21, the connector 26 is connected to the power source, and the heating wire 22 is energized. The polyethylene resin around the heating wire 22, that is, the polyethylene resin on the joint surface 45 of the multilayer tube 41 and the polyethylene resin on the inner peripheral surface of the opening of the electrofusion joint 21 are melted to electrically connect the outer surface of the end portion of the multilayer tube 41 The receiving joint inner surface of the fusion joint 21 is heat-sealed. At this time, the indicator pin 27 protrudes by the melt expansion of the polyethylene resin outside the heating wire 22.

  In this way, the multi-layer pipe 41 having gasoline resistance is used for transporting gasoline at a gas station or the like by connecting by heat fusion using the electric fusion joints 11 and 21 having gasoline resistance. It is possible to easily connect the pipes at the bent portion or branching portion of the pipe to be performed, and the gasoline resistance of the entire pipe is not impaired.

It is a sectional front view for every process explaining the manufacturing process of the electrofusion joint which shows the 1st form example of this invention. It is a cross-sectional front view for every process explaining the manufacturing process of the electrofusion joint which shows the 2nd example of this invention. It is a cross-sectional side view which shows an example of the multilayer pipe | tube connected with the electrofusion joint of this invention. It is a cross-sectional front view of the principal part which shows the state before inserting the edge part of a multilayer pipe in the receptacle of an electric fusion joint. It is a cross-sectional front view of the principal part which shows the state which inserted the edge part of the multilayer pipe in the receptacle of the electric fusion joint.

Explanation of symbols

  11, 21 ... electrofusion joint, 12, 22 ... heating wire, 13, 23 ... joint inner pipe part, 14, 24 ... barrier layer, 15, 25 ... joint outer pipe part, 16, 26 ... connector, 17, 27 ... Indicator pin, 31 ... Core for injection molding, 32 ... Polyethylene-coated heating wire, 41 ... Multi-layer pipe, 42 ... Inner pipe, 43 ... Barrier layer, 44 ... Outer pipe, 45 ... Bonding surface

Claims (3)

  An electric fusion joint for connecting a multi-layer pipe provided with a barrier layer made of an ethylene-vinyl alcohol copolymer between an outer pipe and an inner pipe made of polyethylene resin, the joint inner pipe made of polyethylene resin In addition, a heating wire for melting and joining the polyethylene resin on the outer peripheral surface of the end of the multilayer tube and the polyethylene resin on the inner peripheral surface of the electrofusion joint is buried, and ethylene is embedded on the outer periphery of the inner tube portion of the joint. An electric fusion joint characterized in that a barrier layer made of a vinyl alcohol copolymer is provided, and a joint outer pipe part made of polyethylene resin is provided on the outer periphery of the barrier layer.   An electrical fusion joint manufacturing method for connecting a multilayer pipe provided with a barrier layer made of an ethylene-vinyl alcohol copolymer between an outer pipe and an inner pipe made of a polyethylene resin, wherein the polyethylene resin is injection-molded Forming a joint inner pipe part, winding a heating wire around the outer peripheral surface of the joint inner pipe part after molding, and ethylene-vinyl alcohol copolymer on the outer periphery of the joint inner pipe part after the heating wire winding. An electric fusion process comprising a step of forming a barrier layer by injection molding or inserting a coalescence and a step of injection-molding a polyethylene resin on the outer periphery of the molded barrier layer to form a joint outer pipe portion A method for manufacturing a joint.   A method of manufacturing an electric fusion joint for connecting a multilayer pipe provided with a barrier layer made of an ethylene-vinyl alcohol copolymer between an outer pipe and an inner pipe made of polyethylene resin, the outer periphery of an injection molding core A step of winding a polyethylene-coated heating wire, and a step of molding the inner pipe portion in a state where the heating wire is embedded by placing the injection molding core in a mold and injection-molding polyethylene resin, A step of forming a barrier layer by injection molding or inserting an ethylene-vinyl alcohol copolymer on the outer periphery of the joint inner tube after molding, and a joint outer tube by injection molding polyethylene resin on the outer periphery of the molded barrier layer And a step of forming the part.

Images