Electrofusion joint with connecting member

Description: TECHNICAL FIELD [Detailed description of the invention]

[Industrial application field] The present invention relates to an electrofusion joint with a connecting member for connecting a connected body such as a polyolefin pipe, particularly a conduit for hot water, to a connecting terminal such as a nozzle of a conduit header. [Conventional technology] A crosslinked polyolefin pipe such as silane crosslinked polyethylene is used as a conduit for hot water. This crosslinked polyolefin is excellent in high temperature performance such as heat resistance and high temperature creep characteristics, and has shape retention performance, but unlike non-crosslinked polyolefin, it cannot be fused to the connected body. Therefore, the electrofusion joint used as the joint of the non-crosslinked polyolefin pipe cannot be used as the joint of the crosslinked polyolefin pipe. Also, crosslinked polyolefins cannot be used to form electrofusion joints. Therefore, as a joint for connecting a crosslinked polyolefin pipe or a joint using a crosslinked polyolefin, a joint for mechanically joining is used. However, in the case of hot water pipes, the working pressure is high and strength is required, which makes the structure complicated, and the workability of the pipes is poor. In addition, since sealing is performed by compression, the sealing performance deteriorates due to stress relaxation of the pipes and sealing materials. There is a problem that long-term performance degradation occurs. Further, since the connecting terminal such as the nozzle of the conduit header is usually made of metal, it is difficult to connect such a connecting terminal to the crosslinked thermoplastic resin pipe. Further, in a general electrofusion joint, when the connected body is a thin-walled resin pipe, there is a problem that the connecting portion is deformed by heating and swells inward, and the internal flow path is narrowed. [Problems to be solved by the invention] In order to solve the above problems, the present invention can improve heat resistance by using a crosslinked thermoplastic resin, improve sealing performance by fusion, prevent deformation of the connected body at the time of fusion, and can prevent deformation of the connected body at the time of fusion. It is an object of the present invention to provide an electrofusion joint with a connecting member which can easily connect a plastic resin pipe to a connecting terminal such as a nozzle of a conduit header and has good workability. [Means to solve problems] The present invention is an electrofusion joint with the following connecting members. (1) A crosslinked thermoplastic resin layer and a non-crosslinked thermoplastic resin layer integrally formed with the crosslinked thermoplastic resin layer at a position in contact with an inner connected body on one end side of the crosslinked thermoplastic resin layer. , The heating wire provided on the inside, the outer surface, or the inner surface of the non-crosslinked thermoplastic resin layer, the connecting member inserted and fixed inside the other end side of the crosslinked thermoplastic resin layer, and the above. An electrofusion joint with a connecting member having a connected body support portion provided so as to form a connected body insertion groove inside a non-crosslinked thermoplastic resin layer. (2) The electrofusion joint with a connecting member according to (1) above, wherein the crosslinked thermoplastic resin layer is adhered to the connecting member with a modified thermoplastic resin. (3) The electrofusion joint with a connecting member according to (1) or (2) above, wherein the connected body support portion is integrally formed with a connecting member or a crosslinked thermoplastic resin layer. In the present invention, one end of the crosslinked thermoplastic resin layer and the non-crosslinked thermoplastic resin layer are adjacent to each other and integrated. Since the crosslinked thermoplastic resin does not have fusion properties, even if the crosslinked thermoplastic resin and the non-crosslinked thermoplastic resin after cross-linking are molded by extrusion molding, injection molding, etc., the respective layers are not separated and integrated. When the uncrosslinked crosslinkable thermoplastic resin and the non-crosslinkable thermoplastic resin are heat-molded and integrated, and then the crosslinkable thermoplastic resin is crosslinked, the crosslinked thermoplastic resin and the non-crosslinked thermoplastic resin are integrated and laminated. The body is obtained. In the present invention, a laminate in which a crosslinked thermoplastic resin layer and a non-crosslinked thermoplastic resin layer are integrated is used. The cross-linked thermoplastic resin has a three-dimensional structure by intermolecular cross-linking of the thermoplastic resin, and is cross-linked with a cross-linking agent such as a silane-cross-linked thermoplastic resin or a divinylbenzene-cross-linked thermoplastic resin, as well as an organic peroxide. It may be directly crosslinked by radiation or the like. The non-crosslinked thermoplastic resin is a thermoplastic resin such as polyolefin that does not have crosslinkability and is generally used as a thermoplastic resin. Examples of the thermoplastic resin according to the present invention include polyolefins, and examples of the polyolefin include a single or copolymer of an α-olefin having 2 to 20 carbon atoms, preferably 2 to 12 carbon atoms. Preferred α-olefins include ethylene, propylene, butene-1, 4-methylpentene-1 and the like. As the connecting member, a metal tube or the like having a connecting portion such as a screw to the connecting terminal at one end can be used. The connection member and the crosslinked thermoplastic resin layer are preferably adhered by an adhesive material such as a modified thermoplastic resin. The adhesive material is preferably interposed between the connecting member and the crosslinked thermoplastic resin layer, but may be dispersed in the crosslinked thermoplastic resin layer. As the modified thermoplastic resin, polyolefin is modified with unsaturated carboxylic acid such as acrylic acid and maleic acid; unsaturated carboxylic acid anhydride such as maleic anhydride; amide of unsaturated carboxylic acid; and unsaturated epoxide such as glycidyl methacrylate. Some have been modified by graft copolymerization with a monomer. The content of the modified monomer in the modified thermoplastic resin is preferably in the range of 0.001 to 5% by weight with respect to the modified thermoplastic resin. The connected body support portion is preferably formed integrally with the connecting member or the crosslinked thermoplastic resin layer, but may be formed of another material. The connected body insertion groove is formed so as to open at one end of the electrofusion joint. [Activity] In the electrofusion joint with a connecting member of the present invention, a non-crosslinked thermoplastic resin layer in which heating wires are arranged on the inner, outer surface, or inner surface and a connecting member coated with an adhesive material such as a modified thermoplastic resin are injected. It is manufactured by injecting a crosslinkable thermoplastic resin in a state of being inserted into a molding mold, laminating and integrating them, and then crosslinking the crosslinked thermoplastic resin layer to form a crosslinked thermoplastic resin layer. In this case, the adhesive material may not be coated on the connecting member, but may be dispersed in the crosslinked thermoplastic resin to be injected. Further, the connected body support portion can be formed integrally with the connecting member in advance, or can be integrally formed with the crosslinkable thermoplastic resin layer forming the crosslinked thermoplastic resin layer. In the electrofusion joint manufactured in this way, the connecting member is connected to a connecting terminal such as a nozzle of a conduit header, and the end of the connected body such as a thermoplastic resin tube is inserted into the connected body insertion groove to generate non-crosslinking heat. When the non-crosslinked thermoplastic resin layer is attached so as to be in contact with the plastic resin layer and supported by the connected body support portion and the heating wire is energized, the non-crosslinked thermoplastic resin layer is melted and integrally fused to the connected body. As a result, the metal connection terminal and the resin connected body can be reliably connected in a leakage-prevented state. At the time of this fusion, the connected body such as the thermoplastic resin tube softens as the non-crosslinked thermoplastic resin layer melts, but it may be deformed because the inner surface of the connected body is supported by the connected body support portion. Absent. The surface layer or the whole of the connected body is preferably a thermoplastic resin, particularly a resin having compatibility, and a non-crosslinked thermoplastic resin exhibits particularly excellent fusion property. [Example] Hereinafter, examples of the present invention will be described with reference to the drawings. 1 to 3 are cross-sectional views of an electrofusion joint with a connecting member according to another embodiment. In the figure, reference numeral 1 denotes an electrofusion joint, which is integrally formed with the crosslinked polyolefin layer 2 at a position in contact with the tubular crosslinked polyolefin layer 2 and the inner connected body 5 on the one end side of the crosslinked polyolefin layer 2. The non-crosslinked polyolefin layer 3, the heating wire 4 provided on the inside, outer surface or inner surface of the non-crosslinked polyolefin layer 3, and the connecting member inserted and fixed to the inside of the other end side of the crosslinked polyolefin layer 2. 6 and the modified polyolefin layer 7 as an adhesive material interposed between the insertion portion 6a of the connecting member 6 and the crosslinked polyolefin layer 2, and the connected body insertion groove 8 is formed inside the non-crosslinked polyolefin layer 3. It has a connected body support portion 9 provided in the above. The connected body 5 is made of a tube having a thermoplastic resin layer such as polyethylene, and may be entirely made of a fused thermoplastic resin. However, when a heat-resistant material such as crosslinked polyolefin is used, the outer surface is melted. Use one coated with a adaptable thermoplastic resin. The crosslinked polyolefin layer 2 has a tubular structure that covers the entire circumference of the abutting portion 10 of the insertion portion 6a of the connecting body 5 and the connecting member 6, and is a portion of the portion corresponding to the connecting body 5 on one end side in the longitudinal direction. The non-crosslinked polyolefin layer 3 is laminated on the inner circumference, and the heating wire 4 is embedded inside the non-crosslinked polyolefin layer 3 in FIG. 1, on the outer surface of the heating wire 4 in FIG. 2, and on the inner surface in FIG. The connecting member 6 is made of a metal tube, and a threaded portion 11 as a connecting portion is formed on the protruding portion 6b on the opposite side of the insertion portion 6a, and a hexagonal spanner hook 12 is formed on the intermediate portion. The modified polyolefin layer 7 is interposed between the insertion portion 6a of the connecting member 6 and the crosslinked polyolefin layer 2 over the entire circumference to bond the two. The connected body support portion 9 extends integrally from the insertion portion 6a of the connecting member 6 so as to form a connected body insertion groove 8 with the non-crosslinked polyolefin layer 3. In the above electrofusion joint 1, the non-crosslinked polyolefin layer 3 in which the heating wire 4 is embedded or wound on the inner, outer surface or inner surface, and the insertion portion 6a and the cover of the connecting member 6 in which the outer surface is coated with the modified polyolefin layer 7 are covered. In a state where the connecting body support portion 9 is inserted into the injection molding mold, a crosslinkable polyolefin containing a crosslinking agent, a crosslinking aid, etc. is injected into the polyolefin to be laminated and integrated, and then the crosslinkable polyolefin layer is crosslinked. It is produced by forming a crosslinked polyolefin layer 2. The electrofusion joint 1 manufactured in this way is connected by screwing the threaded portion 11 of the protruding portion 6b of the connecting member 6 into a connecting terminal such as a nozzle of a conduit header. Then, when the connected body 5 such as a polyolefin tube is inserted into the connected body insertion groove 8 and abutted against the insertion portion 6a of the connecting member 6 and the heating wire 4 is energized, the non-crosslinked polyolefin layer 3 melts and the connected body 5 It is fused to and integrated. At the time of fusion, the connected body 5 made of a thermoplastic resin is softened as the non-crosslinked polyolefin layer 3 is melted, or is deformed because the inner surface of the connected body 5 is supported by the connected body support portion 9. Never. Therefore, the flow path of the connected body 5 is not narrowed, and it is possible to maintain a flow path that is almost the same as before the connection. Further, in the above-mentioned electrofusion joint 1, since the tubular crosslinked polyolefin layer 2 bears the heat resistance strength, it is excellent in shape retention even when used for connecting a hot water supply pipe or the like. On the other hand, in a state where the crosslinked polyolefin layer 2 is integrated with the connecting member 6 and the non-crosslinked polyolefin layer 3, the non-crosslinked polyolefin layer 3 is fused and integrated with the connected body 5, so that the sealing property is excellent and the hot water supply pipe can be used. Maintains sealing properties for a long time even when used. FIG. 4 is a cross-sectional view showing another embodiment. In this embodiment, the connected body support portion 9 is integrally formed with the crosslinked polyolefin layer 2 by the crosslinked polyolefin, and has the same effects as those in the above embodiment. FIG. 5 is a cross-sectional view showing still another embodiment. In this embodiment, the connected body support portion 9 is integrally formed with the non-crosslinked polyolefin layer 3 by the non-crosslinked polyolefin. In the above embodiment, the connected body support portion 9 is integrally formed of the same material as the connecting member 6 or the crosslinked polyolefin layer 2, but other materials such as non-crosslinked polyolefin or metal are fixed. You may. Further, although the modified polyolefin layer 7 is separately formed as the adhesive material layer, the modified polyolefin may be dispersed in the crosslinked polyolefin layer 2. Further, the shapes and structures of the crosslinked polyolefin layer 2, the non-crosslinked polyolefin layer 3, the connected body support portion 9, etc. are not limited to those shown in the drawings and can be changed. When the heating wire 4 is provided on the outer surface or the inner surface of the non-crosslinked polyolefin layer 3, it may be wound around the non-crosslinked polyolefin layer 3 or the connected body 5. [Effect of the invention] According to the present invention, the connecting member and the non-crosslinked thermoplastic resin layer are integrated with the crosslinked thermoplastic resin layer, and heating wires are provided on the inside, outer surface or inner surface of the non-crosslinked thermoplastic resin layer. It is possible to obtain an electrofusion joint which is excellent in high temperature performance and sealing property, can prevent deformation of the connected body, and is also excellent in workability such as mounting work.

[Simple explanation of drawings]

1 to 5 are cross-sectional views of another embodiment. In each figure, the same reference numerals indicate the same or corresponding parts, where 2 is a crosslinked polyolefin layer, 3 is a non-crosslinked polyolefin layer, 4 is a heating wire, 5 is a connected body, 6 is a connecting member, 7 is a modified polyolefin layer, and 8 Is the insertion groove of the connected body, and 9 is the support portion of the connected body.