JP3369000B2 - How to connect pipes - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fusing a pipe by irradiating a microwave with a cylindrical core having a specific structure. 2. Description of the Related Art Various methods have been proposed for connecting pipes formed of a thermoplastic resin. As a method of heating and fusing, a conductive pattern such as a nichrome wire is embedded in a resin. (Japanese Patent Publication No. 61-41293, JP-A-64-74381, etc.) and a method of heating by irradiation with electromagnetic waves using a resin in which a substance that absorbs and converts various electromagnetic waves into heat is dispersed. (JP-A-3-186690, JP-A-2-216626, etc.). [0003] The method using electromagnetic waves is characterized in that it can be heated and fused in a non-contact state, and that a jig for bonding is easily formed. [0004] The method of irradiating electromagnetic waves has the advantages as described above. However, in order to obtain sufficient heat, in practice, it is difficult to use a material that converts electromagnetic waves into heat. In order to give a sufficient amount of heat to the resin, it is necessary to use a large amount of the resin, and there is a problem that the physical properties of the resin are greatly reduced, or that the fluidity is poor and a sufficient adhesive strength cannot be obtained. Means for Solving the Problems The present inventors have solved the above-mentioned problems and have intensively studied a method of bonding a pipe easily and inexpensively, and completed the present invention. That is, the present invention relates to a method of connecting a pipe made of a thermoplastic resin by irradiating a microwave with a cylindrical core provided in contact with an outer surface of the pipe at a connection portion. The core of which contains triiron tetroxide, has an inner periphery made of the same material as the pipe, and has a non-penetrating hole provided from the outer periphery toward the inner periphery, and furthermore, the cylindrical core has At least one
It is a pipe connection method characterized by having two connection parts. In the present invention, the resin forming the pipe is not particularly limited as long as it is thermoplastic, and specific examples thereof include polyvinyl alcohol, polyvinyl acetate, polyamide, polyethylene, polypropylene, and copolymers of ethylene and propylene. Polyolefins such as coalescence,
Polystyrene, polyvinyl chloride, polyvinylidene chloride,
Polymethyl methacrylate, or styrene, vinyl chloride, methyl methacrylate, copolymers such as vinylidene chloride, polycarbonate, polyamide, polyester, polyimide, polyether, polyether ketone,
Any material such as a condensed engineering plastic such as polyetheretherketone may be used. [0008] The size, shape and molding method of the thermoplastic resin pipe are not particularly limited as is clear from the gist of the present invention. In the present invention, commercially available iron tetroxide can be used. Natural magnetite is finely pulverized, iron is calcined in the air, iron (III) oxide.
Can be exemplified by a product obtained by reducing water with hydrogen containing steam, or a product obtained by pulverizing a product obtained by applying steam to red-hot iron. The particle size of such ferric oxide is not more than 1000 μm, preferably 0.01 to 100 μm.
m is preferably used. In the present invention, there is no particular limitation on the method for incorporating the above-mentioned triiron tetroxide into the thermoplastic resin forming the inner periphery of the cylindrical core, and any method can be used as long as it can be mixed well. But it is good. For example, it is possible to mix the polymer solution with triiron tetroxide, disperse by mixing well by a well-known mixing method such as a ball mill and a homogenizer, and then form and dry into a shape described below. It is preferable to heat-melt and mix triiron tetroxide. Specifically, after mixing the thermoplastic resin and triiron tetroxide with a Henschel mixer, etc., heat-melt and mix with an extruder, Brabender, etc., and then pelletize to easily form a cylindrical core described later. It is. Here, the ratio of the thermoplastic resin to triiron tetroxide is about 100: 1 to 100: 500 (weight ratio), preferably about 100: 10 to 100: 200 (weight ratio). The shape of the cylindrical core according to the present invention will be described below. FIG. 1 is a cross-sectional view of a connecting portion of a pipe, 1 is a cross-section of a connecting pipe, and 2 is a cross-section of a cylindrical core, which is made of the same material as the pipe. 3 is a portion containing triiron tetroxide. Reference numeral 4 denotes a hole formed from the outer periphery to the inner periphery of the cylindrical core. The size of the hole is not particularly limited as long as the bottom of the hole can be easily observed, and it is necessary that the size of the hole does not impair the strength of the cylindrical core. The depth of the hole is generally such that it does not reach the layer containing triiron tetroxide, and usually a layer having a thickness of about 1/3 to 1/10 of the thickness of the pipe remains. Preferably it is. By observing the bottom of this hole, the layer containing ferric oxide, which is the heat generating layer, is heated and the layer is melted, or the heat is transmitted and the layer containing no ferric oxide is melted. Can be observed. Therefore, if the depth of the hole in this portion is adjusted according to the thickness of the layer that needs to be heated and melted, it becomes possible to observe whether or not sufficient heat has been generated by microwave irradiation. By providing a thin projection at the bottom of the hole, when the bottom portion is melted, the projection bends or falls down, so that the molten state can be more easily observed. FIG. 2 is a longitudinal sectional view of a connecting portion of the pipe, and FIG.
1 to 3 are the same as those in FIG. 1, and 5 is a connecting portion of a cylindrical core.
The cylindrical core is connected at 5 and is usually reinforced with resin bolts. When the bolts are tightened, it is preferable to apply pressure so that the cylindrical core and the outer periphery of the pipe come into close contact with each other. The assembly of the pipe and the cylindrical core as described above is then irradiated with microwaves. The microwave can be heated to the extent that the thermoplastic resin can be sufficiently fused with the wavelength and energy of the degree commercially available as a microwave oven for home use, and the microwave having a frequency of several gigahertz (usually 2.45 gigahertz) can be used. Available, several KW /
Energy of about 1 kg is sufficient. The present invention will be further described with reference to examples. Example 1 10 g of ferric oxide (reagent manufactured by Wako Pure Chemical Industries, Ltd.) and high-density polyethylene manufactured by Nippon Petrochemical Co., Ltd. (brand name Staphrene E)
792) 20 g was mixed well at 240 ° C. with Labo Plastmill R type (manufactured by Toyo Seiki Seisaku-sho, Ltd.). This operation was repeated to obtain about 100 g of the mixture. 220 ° C of the mixture
To form a 1 mm thick sheet. on the other hand,
Similarly, high-density polyethylene manufactured by Nippon Petrochemical Co., Ltd. (brand name: Staphlen E801) was press-molded to obtain a sheet having a thickness of 4 mm. A mixture of triiron tetroxide is 90 mm × 1
A high-density polyethylene was cut out into a sheet having a size of 100 mm × 170 mm and press-formed at 230 ° C. to form a composite sheet having a thickness of 3 mm. When the sheet made by the same operation was cut in the middle, the thickness of the polyethylene part and the triiron tetroxide containing part was 2.4 mm and 0.8 mm.
Was thick. The inner side of the sheet is covered with a pipe having a diameter of 50 mm and a thickness of 5 mm (formed by extrusion molding using a high-density polyethylene manufactured by Nippon Petrochemical Co., Ltd. (brand name: Staflen E801)). As an iron trioxide containing part,
By heating at 240 ° C., a cylindrical core was formed on the outer surface of the pipe. In addition, four holes with an inner diameter of 5 mm and a depth of 2 mm
Opened individually. The connecting portion of the core was about 20 mm, and was connected with a nylon bolt. A commercially available microwave oven (Toshiba Microwave Oven ERT-
540F) and irradiated with microwaves for 8 minutes. Irradiation 7
In 40 minutes, it was observed that the bottom of the hole was melted and changed to reflect well. When it was taken out and the bolt was removed, it was well adhered. A knife was inserted into the connection and it was gouged but did not come off. When the bonded portion was cut into slices and the state of bonding between the cylindrical core and the pipe was observed, it was completely bonded. According to the present invention, pipes can be easily connected by implementing the method of the present invention, which is extremely valuable industrially.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a pipe connecting portion provided with a cylindrical core according to the present invention. FIG. 2 is a longitudinal sectional view of a connection portion of a pipe provided with a cylindrical core according to the present invention. [Description of Signs] 1 Cross section of pipe to be connected 2 Cross section of cylindrical core 3 Inner circumference containing triiron tetroxide 4 Hole provided from outer circumference to inner circumference of cylindrical core 5 Cylindrical core Connection

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-129195 (JP, A) JP-A-47-34768 (JP, A) JP-A-4-321189 (JP, A) JP-A 5- 60288 (JP, A) JP-A-6-55641 (JP, A) JP-A-56-44287 (JP, U) JP-A-3-26897 (JP, U) JP-A-3-91518 (JP, U) WO 93/10962 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 65/00-65/82 F16L 47/02-47/03

Claims (1)

(57) Claims 1. A pipe made of a thermoplastic resin is connected by irradiating a microwave using a cylindrical core provided in contact with an outer surface of the pipe at a connection portion. The method, wherein the cylindrical core comprises ferric oxide.
It has an inner periphery made of the same material as the pipe, has a non-penetrating hole provided from the outer periphery to the inner periphery, and has a cylindrical core having at least one connection portion. Characteristic pipe connection method.