JPH09189394A - Melting device for plastic pipe and plastic pipe melting method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely improve heating efficiency by providing a sleeve having a microwave absorption chamber which is formed by lining a microwave absorber on the internal circumferential walls of connecting plastic counterpipe outer holding parts and both outer holding parts. SOLUTION: The ratio of the diameter of the internal circumference constituted of a microwave absorber 431 which is formed by lining the internal circumferences of end part connecting plastic counterpipe holding parts 41, 42 opened to an opening end of a sleeve 4 and a microwave irradiation chamber 3 and the inside face of the microwave absorption chamber 43 is preferable to be approximately 2-3. An appropriate air insulating layer is formed between the outer circumferential face of the connecting plastic counterpipe held between the connecting plastic counterpipe holding parts 41, 42 and the internal circumferential face of the microwave absorber 431. The temperature rising in the sleeve part is thus reduced, the connecting plastic counterpipe, etc. except for a heating part are prevented from damaged by heat generation of the microwave irradiation, and the leakage of the microwave is reduced from the microwave irradiation chamber 3 through the sleeve 4 so that it can be used safely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic pipe fusing device and a plastic pipe fusing method using the same, and more particularly to a plastic pipe fusing device using microwave heating and a plastic pipe using the same. The fusion method.

[0002]

2. Description of the Related Art Pipes made of thermoplastic resin such as polyethylene, polypropylene and polyvinylidene fluoride are widely used as fluid transport pipes such as water pipes, drain pipes and gas pipes. As a method of joining these thermoplastic resin tubes to each other, for example, as described in JP-A-5-278110, the tube end faces of the tubes to be joined are melted and then pressed in the tube axial direction. The "butt joining (butt joining) method" of joining by means of a joint is widely practiced.

Further, as disclosed in Japanese Patent Publication No. 45-20399, a method of fusion-bonding a joint surface by a joint [electro fusion (EF) joint] having a heating wire inside, "electro fusion" Fusion (E
F) Law ”.

However, in the butt joining method,
Since a hot plate, a heater, etc. for heating and melting both end faces of the tubes are required, the apparatus required for joining becomes large-scale. Furthermore, not only does it take time to bond,
There is a problem in that by pressing in the tube axis direction, beads that largely protrude from the inner and outer edges of the tube end surface where the molten resin is joined can be formed.

Further, in the electrofusion method, since an electrothermal mechanism has to be incorporated in the joint, the manufacturing process is complicated and the cost is high. Also in terms of construction, the heating wire may be damaged in the distribution stage, short-circuited due to energization, and the resin forming the joint in the vicinity of the heating wire may be thermally deteriorated. There is.

As a measure for solving the problems in the butt joining method and the electric fusion method, a microwave fusion joint using a microwave fusion resin in which a conductive material is contained in a thermoplastic resin has been proposed. There is. For example, JP-A-3-
Japanese Patent No. 186690 discloses a fusion-bonded joint for a plastic pipe, which is provided in contact with the outer surface of a thermoplastic pipe to be connected and contains an inorganic substance, an organic substance or the like having a property of generating heat when irradiated with microwaves, A microwave heating fusion-bonding joint for a thermoplastic pipe, which comprises an annular core made of a mixture of a body and a polymer of the same material, and a thermoplastic tubular body closely fitted to the outer periphery of the core. It has been disclosed and is disclosed in the above-mentioned JP-A-3-186690.
1 (1) and 1 (2) of the publication, a microwave radiation source (not shown) is introduced into a heating bonding chamber by a waveguide and a frequency of 245.
An example is shown in which microwaves of 0 MHz and 600 W are transmitted and the thermoplastic pipes are connected using the microwave heating fusion-bonding joint of the thermoplastic pipes (pipe diameter 50 mmφ).

However, in the microwave heating device described in the above-mentioned Japanese Patent Laid-Open No. 3-186690, there is no means for preventing microwave leakage, and the outside diameter of the connected thermoplastics pipe, that is, the connected thermoplastics. When the inner diameter of the insertion sleeve of the tube exceeds the length of about 1/2 of the wavelength of the microwave, the sleeve does not serve as a cut-off waveguide, and the sleeve portion has almost no leak prevention function. It is difficult to keep the level below the level at which there is no harmful effect on the human body, and not only that, but the heating efficiency is significantly degraded, and the sleeve itself absorbs the microwaves and heats up in the sleeve itself. It has a problem.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to prevent microwave leakage in a sleeve portion of a microwave heating device and to perform heating safely. An object of the present invention is to provide a highly efficient plastic pipe fusion device and a plastic pipe fusion method using the same.

[0009]

According to the present invention, there is provided a fusion device for a plastic pipe having a microwave irradiation chamber and a sleeve for supporting a plastic pipe to be connected at a side end of the microwave irradiation chamber. The sleeve has an open end and a plastic pipe outer surface gripping portion provided at an end connected to the microwave irradiation chamber and a diameter-increased inner peripheral wall between the plastic pipe outer surface gripping portions to absorb microwaves. A gist of a fusion bonding device for a plastic tube is a microwave absorbing chamber having a space in which a body is stretched.

According to a second aspect of the present invention, a plastic pipe is connected by using a pipe joint containing a material that absorbs microwave power to generate heat, and the pipe joint portion is melted with the plastic pipe according to the first aspect. A method for fusing a plastic pipe, characterized in that the plastic pipe is housed in a microwave irradiation chamber of the welding device, and the microwave is applied while the connected plastic pipe is held on the inner surface of the sleeve of the fusion device. Is.

The plastic material forming the plastic pipe is not particularly limited as long as it is a thermoplastic resin that can be extruded or injection-molded. For example, ethylene,
Mainly composed of polymers and copolymers of mono-olefins such as propylene and butene, for example, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, ethylene-propylene block copolymer Polymer, ethylene-propylene random copolymer, polybutene-1, polymethylpentene-1
Polyolefin resin such as, vinyl chloride resin, polycarbonate, polyethylene terephthalate, polyester resin such as polybutylene terephthalate, polyamide,
Acrylic resin, polyphenylene sulfide (PP
S), polysulfide, polyethersulfone, polyetheretherketone, polyvinylidene fluoride (PV
DF), polyvinylidene chloride (PVDC), perfluoroalkoxy fluororesin (PFA) and the like. These may be used alone or in combination of two or more.

In the microwave fusion splicing joint, a heating portion made of a microwave fusion plastic composition in which a conductive material that absorbs microwave power to generate heat is mixed with the plastic material forming the plastic pipe is a plastic to be connected. It is a joint provided near the fusion-bonded portion of the inner surface or the outer surface to be joined to the pipe.

The above-mentioned conductive substance has a conductivity of 0.1.
Inorganic conductive materials, organic conductive materials and the like are not particularly limited as long as they are in the vicinity of S / cm or higher,
For example, examples of the inorganic conductive substance include ferrite powder, and examples of the organic conductive substance include carbon black, polyaniline, polythiophene, polypyrrole, polyacetylene, polyphenylacetylene, polyphenylene, polyfuran, polyperinaphthalene, and alkyl groups and alkoxy groups thereof. Examples thereof include organic polymer substances such as substitution products of groups. Above all, aniline-based polymer fine particles are preferably used.

The aniline-based polymer fine particles are, for example,
The aniline derivative monomer and the acid are dissolved in a solvent such as water, and an oxidant is added to this solution, and the mixture is stirred to carry out oxidative polymerization.

Examples of the aniline derivative monomer include aniline, N-methylaniline, N-ethylaniline, o-toluidine, m-toluidine, 2-ethylaniline, 3-ethylaniline, 2,3-dimethylaniline, 2 , 5-dimethylaniline, 2,6-dimethylaniline, 2,6-diethylaniline, 2-methoxyaniline, 3-methoxyaniline, 2,5-dimethoxyaniline, 3,5-dimethoxyaniline, o-phenylenediamine, m -Phenylenediamine, 2-aminobiphenyl, N, N-diphenyl-p-phenylenediamine and the like can be mentioned. The concentration of the aniline derivative monomer in the solvent is preferably 0.1 to 1 mol / l.

Examples of the acid include inorganic protonic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; inorganic acid esters such as sulfuric acid ester and phosphoric acid ester; organic acids such as p-toluenesulfonic acid and carboxylic acid; polystyrene. Polymeric acids such as sulfonic acid may be mentioned. The concentration of the acid is 0.1 N
1N is preferred.

Examples of the oxidizing agent include persulfate,
Examples thereof include peroxides such as hydrogen peroxide, permanganate, and dichromate; Lewis acids such as lead dioxide, manganese dioxide, and iron chloride. The concentration of the oxidizing agent is preferably 0.1 to 1 mol / l with respect to the solvent.

The aniline-based polymer fine particles can be prepared by the above method, but commercially available products such as "Versicon" manufactured by Allied Signal Co. can also be used.

The above conductive aniline polymer fine particles are
It is used as a microwave fusion plastic composition by containing 5 to 100 parts by weight to 100 parts by weight of the plastic having thermal adhesiveness to the plastic constituting the tubular body. When the content is less than 5 parts by weight, sufficient fusion bonding strength cannot be obtained at the time of butt joining of pipes, and when the content is more than 100 parts by weight, the microwave fusion plastic composition becomes a brittle material. The joint strength of the joint is reduced.

When the conductive material is mixed with the plastic, a sufficient kneading is given as a mixing means,
The conductive material is not particularly limited as long as it can be uniformly dispersed in the plastic, for example,
A single screw extruder, a twin screw extruder, a Banbury mixer, a roll, a Brabender plastograph, a kneader, etc. can be used.

The aniline polymer fine particles dispersed in the thermoplastic resin have a particle diameter of 0.1 to 100 μm.
Although it is desirable to use those in the range of m, secondary kneading may occur in the plastic composition, and sufficient kneading must be given to the plastic composition. It is desirable that the degree of kneading is measured by measuring the particle size of the aniline-based polymer particles dispersed in the plastic composition, and controlling this as the dispersed particle size.

The dispersed particle size of the aniline polymer fine particles is not particularly limited as long as the particle size can be accurately measured. For example, the microwave fusion plastic dyed with RuO ₄ in advance is used. When the composition is measured by backscattered electron of a scanning electron microscope, it can be measured relatively easily.

A large amount of energy is required to disperse the aniline-based polymer fine particles in a state where the dispersed particle size is less than 0.1 μm, and a device for dispersion becomes large,
It is not preferable in terms of cost. The dispersed particle size is 100μ
When it exceeds m, the calorific value becomes small, and the necessary calorific value cannot be obtained unless the content is more than 100 parts by weight with respect to 100 parts by weight of the plastic.

Examples of the microwave irradiation source of the microwave fusion device include, for example, 2.
A 45 GHz magnetron is used as an oscillation tube, and the microwave power generated in the oscillation tube is guided to the microwave irradiation chamber through the waveguide. The irradiation power is 100 to 2,0.
00W or the like is preferable.

The waveguide from the magnetron of the microwave irradiation source to the microwave irradiation chamber has a short-circuited end, and has a length of ¼ wavelength of the microwave in the waveguide. By setting the tube length of the waveguide in this way, the phases of the microwaves are aligned and the microwaves can be transmitted to the microwave irradiation chamber without loss.

The method of mounting the waveguide from the magnetron of the microwave irradiation source to the microwave irradiation chamber to the microwave fusion device is not particularly limited, but, for example, when a bayonet mechanism is used. It is not necessary to prepare an apparatus for each diameter of a plurality of types of pipe materials, and the microwave fusion bonding apparatus can be used most efficiently by a simple preparation work.

The microwave irradiation time varies depending on the size and shape of the tubular body to be joined, but is, for example, 50.
When joining mmφ or 75 mmφ gas medium-density polyethylene pipes to each other, a microwave is irradiated by a dedicated microwave irradiator to 120 to 1 until fusion is completed.
It is 80 seconds, generally 10 to 180 seconds.

The sleeve has an electromagnetic wave on an expanded inner peripheral wall between the outer surface gripping portion of the connected plastic tube and the outer surface gripping portions of the connected plastic tube provided at the open end and the end connected to the microwave irradiation chamber. The absorber is composed of a radio wave absorption chamber having a stretched space, and is provided at both ends of the microwave irradiation chamber, and a connected plastic pipe is connected to both connection ends of the microwave fusion joint. Alternatively, the microwave fusion may be performed by fusion, and when the microwave fusion joint is a stopper, it may be provided only on one surface of the microwave irradiation chamber. or,
If the microwave fusion splicing joint is a 90 ° elbow or a branch joint or valve having three or more directions, the required number of sleeves are provided on the wall surface in the connecting direction of the plastic pipe to be connected. Should be provided.

The radio wave absorber stretched on the inner peripheral wall of the radio wave absorbing chamber is, for example, a radio wave absorber obtained by binding a radio wave absorber such as ferrite, silicon carbide, or carbon directly or by using a heat-resistant inorganic cement as a binder. An absorber may be used. Further, when the ratio of the diameter of the connected plastic pipe to the wavelength of the microwave is within several times, the microwave absorber is stretched on the inner peripheral wall of the electromagnetic wave absorbing chamber so that the microwave is absorbed uniformly. It is preferable that the inner peripheral wall of the radio wave absorption chamber constitutes an annular wall surface.

When the ratio of the pipe diameter of the connected plastic pipe to the wavelength of the microwave exceeds several times and the pipe diameter becomes large, the inner peripheral wall of the electromagnetic wave absorbing chamber does not need to be annular. Even if it is formed in any shape, it does not hinder the fusion work of the plastic pipe. Especially when the diameter of the plastic pipe to be connected is much larger than the wavelength of the microwave, if the inner surface is a sharp uneven surface in which pyramids are densely arranged,
The microwave absorption is performed more effectively.

The inner diameter of the inner peripheral wall of the electromagnetic wave absorbing chamber in which the electromagnetic wave absorber is stretched is preferably 2 to 3 times the inner diameter of the outer surface gripping portion of the plastic pipe to be connected. A sufficient heat insulating layer can be formed between the outer surface of the plastic tube to be connected and the outer surface of the plastic tube to be connected. When the inner diameter of the inner peripheral wall of the electromagnetic wave absorber in which the electromagnetic wave absorber is stretched is out of the above range, if the upper limit of the above range is not satisfied, the entire fusion bonding apparatus becomes large and the usability becomes poor, and the lower limit of the above range is set. If it comes off, the heat insulation during fusion of the plastic pipe to be connected may not be sufficient, and the plastic pipe may be deformed after the connection.

Further, if necessary, heat radiation fins may be provided on the outer peripheral wall of the electromagnetic wave absorbing chamber to further lower the temperature in the electromagnetic wave absorbing chamber.

The microwave irradiation chamber and the sleeve of the above-mentioned microwave fusion device are not particularly limited in the structure for opening and closing, but only one surface of the microwave irradiation chamber can be opened and closed, and the narrow microwave irradiation chamber. In order to avoid the inconvenience of inserting the connected plastic pipe into the microwave fusion joint, for example, in a plane containing the center line of the connected plastic pipe and the outlet of the microwave fusion joint, or continuously It is preferable that the structure is divided into parts and can be opened and closed.

The method for connecting the microwave fusion splicing joint and the plastic tube to be connected is not particularly limited,
For example, any joining method conventionally used for joining plastic pipes such as a taper sleeve method, a butt joining method, and a flange joining method in which the opening of the microwave fusion joint is gradually reduced in diameter is applicable. . At the time of the joining, the plastic pipe to be connected is gripped by the plastic pipe outer surface gripping portion of the sleeve connected to the microwave irradiation chamber and is fixed at the fusion position of the microwave fusion joint. In order to stabilize the attachment position, an auxiliary fixing tool made of a material having a small thermal adhesive property with the plastic tube to be connected may be used as necessary.

Since the plastic pipe fusing device of the present invention according to claim 1 is constructed as described above, a sufficient area for absorbing microwaves is formed, and the absorbed power per unit is small. Therefore, the temperature of the sleeve part does not rise so much that the plastic pipe to be connected other than the heat generating portion is not damaged by thermal deformation due to the heat generated by the microwave irradiation, and the microwave is passed from the microwave irradiation chamber through the sleeve. There is little leakage, and the operator can use it safely without worrying about any damage due to microwave exposure.

Since the method for connecting plastic pipes according to the second aspect of the present invention is configured as described above, heat generated by microwave irradiation causes damage such as thermal deformation to the connected plastic pipes other than the heat generating portion. It is possible to use it safely without giving it, and since there is little leakage of microwaves from the microwave irradiation chamber through the sleeve, there is no fear of the operator being hindered by microwave exposure.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

(Embodiment 1) FIG. 1 is a perspective view showing a situation in which a plastic pipe is fused by a microwave fusion joint using the plastic pipe fusion device of the present invention. By showing the internal plastic pipe and the microwave fusion joint through the outer wall of the device, the positional relationship between the fusion device and the connected plastic pipe and the microwave fusion joint will be described. Reference numeral 1 is a magnetron which is a microwave irradiation source, and 2 is a waveguide, which is connected to a circular waveguide from a rectangular waveguide 21 to a rectangular circular converter 22 and opened to the microwave irradiation chamber 3. The open end is a short-circuited end, and microwaves can be efficiently transmitted. 23 is a bayonet.

Reference numeral 4 is a sleeve, 41 and 42 are gripped portions of the connected plastic tube 5 at the open end of the sleeve and the end opening to the microwave irradiation chamber 3, and 43 is a microwave absorption chamber. Reference numerals 431 denote microwave absorbers stretched on the inner wall of the microwave absorption chamber 43. The microwave absorbing chamber 43 is expanded in diameter from the connected plastic pipe 5 gripping portions 41 and 42, and a space is formed between the external surface of the connected plastic pipe 5 and the microwave absorber 431.

The microwave irradiating chamber 3 and the sleeves 4 and 4 connected to the microwave irradiating chamber 3 are divided into two parts on the plane including the center of the plastic tube 5 to be connected, and the plastic tube 5 to be connected and the microwave fusion joint 6 are microwaved. It is set at a predetermined position in the absorption chamber 43, the connected plastic pipe 5 and the microwave fusion joint 6 are connected, and after fusion, the integrated plastic pipe 5 and the microwave fusion joint 6 have an integrated length. It is easy to take out the scale. In the embodiment shown in FIG. 1, the upper chamber 31 of the microwave irradiation chamber 3 and the lower chamber 32 of the microwave irradiation chamber 3 which are divided into two are connected rotatably about a hinge 33. Reference numerals 34 and 34 are grips and fixtures for opening and closing the microwave irradiation chamber 3.

FIG. 2 is a partially cutaway perspective view showing a part of the microwave irradiation chamber 3 and an inner surface of the sleeve 4 connected to the microwave irradiation chamber 3, and an open end of the sleeve 4 and an end opening to the microwave irradiation chamber 3. The ratio of the diameters of the inner circumferences of the part-to-be-connected plastic tube grips 41 and 42 and the inner circumference formed by the microwave absorber 431 stretched on the inner surface of the microwave absorption chamber 43 is preferably about 2 to 3. Shows that an appropriate heat insulating layer is formed between the outer peripheral surface of the connected plastic tube 5 held between the connected plastic tube holding parts 41 and 42 and the inner peripheral surface of the microwave absorber 431. ing.

(Embodiment 2) Next, using the apparatus shown in FIGS. 1 and 2, a nominal diameter of 75 (outer diameter 89 mmφ, thickness 8.
1 mm) polyethylene pipe for city gas was connected by a microwave fusion joint. Preparation of adhesive layer sheet Medium density polyethylene (Mitsui Petrochemical Co., Ltd., MFR = 0.
2 g / 10 min) was formed into a sheet having a thickness of 0.3 mm. Preparation of heat generating layer sheet Medium density polyethylene (Mitsui Petrochemical Co., Ltd., MFR = 0.
2 g / 10 min) 100 parts by weight and aniline-based polymer particles (manufactured by Allied Signal Co., trade name: Versi
con) 30 parts by weight were mixed and molded into a sheet having a thickness of 0.5 mm.

The heat generating layer sheet was sandwiched between the two adhesive layer sheets by a heat laminator to prepare a resin sheet for microwave fusion.

The obtained resin sheet for microwave fusion is wound around a pair of core portions of an insert mold for pipe fitting by winding it into a cylindrical shape with a length of 45 mm. A microwave fusion tube fitting (cheese) having the same size as a gas HF (heat fusion) fitting (cheese) having a nominal diameter of 75 made of the same material as the sheet was produced.

The same microwave fusion pipe joint was connected to the same polyethylene pipe for gas with a nominal diameter of 75 as that used for the pipe joint, which was used for microwave (2.45 GHz).
(1 z kW, 1 kW) for 120 seconds to fuse the tube body to the microwave fusion tube joint.

In order to evaluate the fusion strength between the fused pipe and the pipe joint, a test piece was cut out from the overlapping fusion portion of the pipe and the pipe joint, and the T-type peel strength was measured. The test results show that the peel strength is 40 kg / cm or more, and that they are firmly fused. Further, in the tensile strength test of the joint portion of the above-mentioned tubular body, the tensile strength was 150 kg / cm ² or more, and the portion other than the joint portion was broken.

(Example 3) From the resin sheet for microwave fusion prepared in Example 2, a nominal diameter of 75 (outer diameter 89 mm) was obtained.
An annular resin sheet for microwave fusion was cut out in accordance with the cut sectional shape of a polyethylene pipe for gas (φ, thickness 8.1 mm). Next, a cheese having a nominal diameter of 75 for a spigot joint for gas to be used for butt fusion bonding is prepared in a joint shape in which the joint end has the same outer diameter dimension as the pipe, and the end of the spigot joint and the nominal diameter of 75 are prepared. Between the ends of the polyethylene pipe for gas, the annular resin sheet for microwave fusion is sandwiched and abutted against each other, and the two polyethylene pipes for gas are pressed from both directions, and the microwave (2.45 GHz) is used.
z, 1 kW) for 180 seconds to fuse the polyethylene pipes for gas to the spigot joints.

In order to evaluate the fusion strength between the fused pipe and the pipe joint, a tensile strength test was conducted on the joint portion of the pipe. As a result of the test, the tensile strength was 150 kg / cm ² or more, and the portion other than the joined portion was broken.

[0049]

Since the apparatus for fusing a plastic pipe of the present invention according to claim 1 is constructed as described above, a sufficient area for absorbing microwaves is formed, and the absorbed power per unit is absorbed. Since the temperature rise of the sleeve part is small, heat generated by microwave irradiation does not cause damage such as thermal deformation to the connected plastic pipes other than the heat generating part, and the sleeve is passed through the sleeve from the microwave irradiation chamber. There is little leakage of microwaves, and it can be used safely without any concern for workers due to microwave exposure.

Since the plastic pipe connecting method of the present invention according to claim 2 is constructed as described above, microwave energy is efficiently converted into heat by heat generation by microwave irradiation, and at the same time, heating in a large area. It does not cause damage such as thermal deformation to the connected plastic pipes other than the heat generating part, and there is little microwave leakage through the sleeve from the microwave irradiation chamber, so there is no concern for workers to be hindered by microwave exposure. It is safe to use.

[0051]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a fusion bonding apparatus for plastic pipes of the present invention, showing a situation in which plastic pipes are connected by a microwave fusion joint, with an outer wall of the fusion bonding apparatus seen through.

FIG. 2 is a partially cutaway perspective view showing, in an enlarged manner, a part of a microwave irradiation chamber 3 and a sleeve 4 connected to the microwave irradiation chamber 3 of the fusion bonding apparatus for plastic pipes shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetron 2 waveguide 21 square waveguide 22 square circular converter 23 bayonet 3 microwave irradiation chamber 31 microwave irradiation chamber upper chamber 32 microwave irradiation chamber lower chamber 33 hinge 34 microwave irradiation chamber opening / closing tool 4 sleeve 41, 42 Connected Plastic Pipe Grip 43 Microwave Absorption Chamber 431 Microwave Absorber 5 Connected Plastic Pipe 6 Microwave Fusion Joint

Claims (2)

[Claims] 1. A fusion device for a plastic pipe having a microwave irradiation chamber and a sleeve for supporting a plastic pipe to be connected at a side end of the microwave irradiation chamber, wherein the sleeve has an open end and the microwave irradiation. A microwave absorption chamber having a space in which a microwave absorber is stretched on an expanded inner peripheral wall between the connected plastic pipe outer surface grip portion provided at the end connected to the chamber and the connected plastic pipe outer surface grip portions. A fusion device for a plastic pipe, which comprises: 2. A microwave irradiation chamber of a fusion device for a plastic pipe according to claim 1, wherein a plastic pipe is connected using a pipe joint containing a material that absorbs microwave power and generates heat. And irradiating with microwaves in a state in which the plastic tube to be connected is gripped on the inner surface of the sleeve of the above-mentioned fusing device.