JPH0861581A - Pipe connecting method - Google Patents

Abstract

PURPOSE: To enhance the connecting strength of pipes made of thermoplastic resin which are fusion attached by irradiation of microwaves using a cylindrical core, wherein the enhancement of the connecting strength is obtained by including triiron tetroxide in thermoplastic resin to form the intermediate layer of the cylindrical core of a specific structure. CONSTITUTION: When pipes 1 of thermoplastic resin are connected, a cylindrical core 2 is fited on the connection part of pipes 1, and connection is generated by irradiation of microwaves using the core 2. The core 2 is formed from a material of the same series as the pipes 1, and an intermediate layer 3 made of a material of the same series as the pipes 1 and containing triiron tetroxide is furnished nearer the bore. A hole 4 is formed directed inward from the periphery, and at least one connection part 5 is provided. Ocular check if the heat emission layer 3 is melted, and if the layer not containing triiron tetroxide is melted, is performed by observing the bottom of the hole 4, and the result from this ocular check is used to perform control of the heated condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fusing a pipe by irradiating it with microwaves using a cylindrical core having a specific structure.

[0002]

2. Description of the Related Art Various proposals have been made for a method of connecting pipes molded of a thermoplastic resin. As a heat fusion method, a conductive pattern such as a nichrome wire is embedded in the resin to flow an electric current. A method of fusion by Joule heat (Japanese Patent Publication No. 61-41293, Japanese Patent Publication No. 64-74381, etc.) and a method of heating by irradiation of electromagnetic waves using a resin in which a substance that absorbs various electromagnetic waves and converts them into heat is dispersed. 3-186690, JP-A-2-261626, etc.).

The method using electromagnetic waves is characterized in that it can be heat-fused in a non-contact state and that a jig for bonding can be easily formed.

[0004]

The method of irradiating electromagnetic waves has the advantages as described above, but in actual practice, if sufficient heat is generated, a substance that converts electromagnetic waves into heat is expensive or resin In order to give a sufficient amount of heat generation, it is necessary to use a large amount, and there have been problems that the physical properties of the resin are greatly deteriorated, or the fluidity is poor and sufficient adhesive strength cannot be obtained.

[0005]

[Means for Solving the Problems] The present inventors completed the present invention by intensively studying a method of adhering pipes inexpensively and easily by solving the above problems.

That is, the present invention relates to a method for connecting a pipe made of a thermoplastic resin by irradiating with microwaves using a cylindrical core provided in contact with the outer surface of the pipe at the connecting portion. The core of, has an intermediate layer from the inner circumference made of the same material as the pipe, containing ferrosoferric oxide, and has a non-penetrating hole provided from the outer circumference to the inner circumference. A method of connecting pipes, wherein the core has a shape having at least one connecting portion.

In the present invention, the resin forming the pipe is not particularly limited as long as it is thermoplastic, and specifically, polyvinyl alcohol, polyvinyl acetate, polyamide, polyethylene, polypropylene, or a copolymer of ethylene, propylene, etc. Polyolefins such as coalesced,
Polystyrene, polyvinyl chloride, polyvinylidene chloride,
Polymethylmethacrylate, or copolymers such as styrene, vinyl chloride, methylmethacrylate, vinylidene chloride, polycarbonate, polyamide, polyester, polyimide, polyether, polyetherketone,
Any kind of condensation type engineering plastic such as polyetheretherketone may be used.

The size, shape and molding method of the thermoplastic resin pipe are not particularly limited, as is clear from the spirit of the present invention.

In the present invention, commercially available ferric tetroxide can be used, which is obtained by pulverizing natural magnetite or by calcination of iron in air, iron (III) oxide.
Examples thereof include those obtained by reducing water with steam-containing hydrogen, and those obtained by finely pulverizing red hot iron with water vapor. The particle size of such ferrosoferric oxide is 1000 μm or less, preferably 0.01 to 100 μm.
Those having a size of about m are preferably used.

In the present invention, the method of incorporating the above-mentioned iron (III) tetroxide into the thermoplastic resin forming the intermediate layer of the cylindrical core is not particularly limited, and any method can be used as long as it can be well mixed. But good. For example, it is also possible to mix ferric tetroxide with a polymer solution, mix well by a known mixing method such as a ball mill and a homogenizer, and then disperse and mold and dry it into the shape described below. It is preferable to heat-melt and mix the iron oxide and the ferrosoferric oxide. Specifically, it is easy to mold the cylindrical core described below by mixing the thermoplastic resin and ferrosoferric oxide with a Henschel mixer, etc., then heating and melting with an extruder, Brabender, etc., and then pelletizing. Is.

The ratio of the thermoplastic resin to the iron (III) tetroxide is about 100: 1 to 100: 500 (weight ratio), preferably about 100: 5 to 100: 200 (weight ratio).

The shape of the cylindrical core in 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 pipe to be connected, 2 is a cross section of a cylindrical core, and is made of the same material as the pipe. 3 is a part containing ferrosoferric oxide. Further, 4 is a hole opened from the outer circumference to the inner circumference 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, but it is necessary that the size of the hole does not impair the strength of the cylindrical core even if it is large. The depth of the hole is generally such that it does not reach the layer containing ferrosoferric oxide, and usually the layer has a thickness of about 1/3 to 1/10 of the thickness of the pipe. Preferably.

By observing the bottom of the hole, the layer containing ferrosoferric oxide, which is a heat generating layer, is heated and the layer is melted, or the heat is transmitted to melt the layer not containing ferrosoferric oxide. Can be observed. Therefore, by adjusting the depth of the holes in this portion in accordance with the thickness of the layer that needs to be heated and melted, it becomes possible to observe whether or not sufficient heat was generated by microwave irradiation. By providing a thin protrusion on the bottom of the hole, the molten state can be more easily observed because the protrusion bends or falls when the bottom portion melts.

FIG. 2 is a vertical sectional view of a connecting portion of a pipe.
3 to 3 are the same as those in FIG. 1, and 5 represents a connecting portion of a cylindrical core.
The cylindrical cores are connected at 5 parts and are usually reinforced with resin bolts. When the bolts are tightened, it is preferable to apply pressure so that the cylindrical core and the outer circumference 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. Microwaves can be heated to the extent that the thermoplastic resin is sufficiently fused with a wavelength and energy that are commercially available as microwave ovens for household use, and microwaves with a frequency of several gigahertz (usually 2.45 gigahertz) are generated. Available, several KW /
Energy of about 1 kg is sufficient.

[0016]

EXAMPLES The present invention will be further described with reference to the following examples.

Example 1 10 g of iron trioxide (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) and 20 g of high-density polyethylene (brand name: Stafrene E792) manufactured by Nippon Petrochemical Co., Ltd. were added to a Labo Plastomill R type (Toyo Seiki Seisakusho Co., Ltd.). (Manufactured by KK) and mixed well at 240 ° C. This operation was repeated to obtain about 100 g of a mixture. 220 mixture
A sheet having a thickness of 1 mm was formed by press molding at ℃. On the other hand, high-density polyethylene (brand name: Staflen E801) manufactured by Nippon Petrochemical Co., Ltd. was similarly press-molded to a thickness of 1 m.
m sheets and 3 mm sheets were obtained.

90 mm × 1 mixed with ferrosoferric oxide
Cut out into a sheet of 60 mm, and the high-density polyethylene is 100 mm in thickness of 1 mm and 3 mm, respectively.
It was cut out into a size of 170 mm and was laminated so that the sheet in which ferrosoferric oxide was dispersed was in the center, and press-molded at 230 ° C. to obtain a composite sheet having a thickness of 3 mm. When a sheet made by the same operation was cut in the middle, the thicknesses of the polyethylene part, the ferrosoferric oxide-containing part and the polyethylene part were 0.6 mm and 0.8
mm and 1.6 mm in thickness.

This sheet was heated at 240 ° C. so as to cover a pipe having an outer diameter of 50 mm and a thickness of 5 mm (high-density polyethylene manufactured by Nippon Petrochemical Co., Ltd. (brand name: Stafrene E801) formed by an extrusion molding method). After molding, a cylindrical core was molded on the outer surface of the pipe. Further, four holes having an inner diameter of 5 mm and a depth of 1.2 mm were formed on the outer side. The core connection was about 20 mm and was connected with nylon bolts. Figure 1,
The one set as in 2 was put in a commercially available microwave oven (Toshiba microwave oven ERT-540F manufactured by Toshiba) and irradiated with microwaves for 8 minutes. It was possible to observe that the bottom of the hole melted and changed at 7 minutes and 40 seconds after irradiation, and the light reflected well. When I took it out and removed the bolt, it was well bonded. I inserted a knife into the connection part and pierced it, but it did not come off. Further, when the bonded portion was cut into slices and the bonding state of the cylindrical core and the pipe was observed, they were completely bonded.

[0020]

INDUSTRIAL APPLICABILITY By carrying out the method of the present invention, a pipe can be easily connected, which is extremely valuable industrially.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a connecting portion of a pipe provided with a cylindrical core according to the present invention.

FIG. 2 is a vertical sectional view of a connecting portion of a pipe provided with a cylindrical core according to the present invention.

[Explanation of symbols]

1 Cross-section of pipe to be connected 2 Cross-section of cylindrical core 3 Intermediate layer containing ferrosoferric oxide 4 Hole provided from the outer circumference to the inner circumference of the cylindrical core 5 Connection part of the cylindrical core

Claims (1)

[Claims] 1. A method for connecting a pipe made of a thermoplastic resin by irradiating with microwaves using a cylindrical core provided in contact with an outer surface of the pipe at a connecting portion, wherein the cylindrical core is Containing ferrosoferric oxide,
It has an intermediate layer from the inner circumference made of the same material as the pipe,
A method for connecting pipes, characterized in that it has a hole that does not penetrate from the outer circumference toward the inner circumference, and that the cylindrical core has at least one connection portion.