JP3340254B2 - How to connect pipes - Google Patents

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 a microwave with a bonding jig having a specific structure. More specifically, the present invention relates to a method for bonding a pipe using a bonding jig having a specific shape and a cylindrical core.

[0002]

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 to flow a current. A method of fusing by Joule heat (JP-B-61-41293, JP-A-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-2-216626, 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]

Although the method of irradiating electromagnetic waves has the advantages as described above, in practice, in order to obtain sufficient heat generation, a large amount of a substance that absorbs electromagnetic waves and converts it into heat is contained in the resin. The layer in which the substance that generates heat by the irradiation of the electromagnetic wave is dispersed and the portion that covers the layer differ greatly in fluidity. Therefore, there is a problem that it is difficult to mold as an integral molded product.

[0005]

Means for Solving the Problems The inventors of the present invention have solved the above-mentioned problems, and have earnestly studied a method of bonding a pipe inexpensively and easily, and have 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 the pipe is made of the same material as the pipe, and the inside diameter of both ends is larger than the outside diameter of the pipe, and the inside diameter is continuously narrowed toward the inside, and has a through hole. And the outer diameter is at least larger than the minimum inner diameter of the cylindrical core, and the outer diameter of one end is larger than that of the other, from the larger end to the smaller end. A cylindrical bonding jig made of the same material as the pipe, containing a substance that generates heat when irradiated with microwaves, and that is continuously reduced at the same rate of change as the inner diameter of the cylindrical core. Inserted between the cylindrical core and the pipe is a pipe connection method and then irradiating microwaves.

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 copolymers such as styrene, vinyl chloride, methyl methacrylate, and vinylidene chloride; condensed engineering plastics such as polycarbonate, polyamide, polyester, polyether, polyetherketone, polyetheretherketone, polysulfone, and polyimide Anything 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, as the substance which generates heat when irradiated with microwaves, any substance having such properties can be used. Specifically, titanium oxide, triiron tetroxide, etc. , Copper oxide, zinc oxide, and the like, and particularly preferably, acicular titanium oxide and triiron tetroxide are used.

As the acicular titanium oxide, a commercially available one can be used. The acicular titanium oxide has a minor axis of 0.01 to 10 μm and an aspect ratio of 5 to 1000, and may be magnesium, calcium, etc. A material doped with another metal oxide, a material doped with tin oxide, indium oxide or the like to make it conductive, or a commercially available material can be used as it is. The crystal form of titanium oxide may be either rutile type or anatase type, but it is necessary that the fine particles have a needle shape. Also, commercially available iron trioxide can be used, and natural magnetite is finely pulverized, or iron is calcined in air,
Examples thereof include a product obtained by reducing iron (III) oxide with hydrogen containing water vapor, a product obtained by pulverizing a material obtained by applying steam to red-hot iron, and the like. The particle size of such ferric oxide is not more than 1000 μm, preferably not more than 0.0 μm.
Those having a size of about 1 to 100 μm are preferably used.

In the present invention, there is no particular limitation on the method of causing the thermoplastic resin forming the cylindrical bonding jig to contain the substance which generates heat when irradiated with the microwave, as long as it can be mixed well. Any method may be used. For example, a substance that generates heat when irradiated with microwaves to a polymer solution is mixed, mixed well by a well-known mixing method such as a ball mill or a homogenizer, and then dispersed and then formed into a shape described below. It is preferable to heat-melt and mix the plastic resin powder and a substance that generates heat when irradiated with microwaves. Specifically, a thermoplastic resin and a substance that generates heat when irradiated with microwaves are mixed with a Henschel mixer, etc., and then heated and melted and mixed with an extruder, Brabender, etc., and then formed into a pellet to form a bonding jig described below. It is easy to do.

The ratio of the thermoplastic resin to the substance that generates heat when irradiated with microwaves is 100: 1 to 100:
About 500 (weight ratio), preferably 100: 10 to 10
It is about 0: 200 (weight ratio).

The shapes of the cylindrical core and the bonding jig according to the present invention will be described below. FIG. 1 is a cross-sectional view of a connecting portion of a pipe, and 1 is a cross section of a cylindrical core covering the pipe, which is made of the same material as the pipe. Reference numeral 4 denotes a through hole provided in the cylindrical core, and the through hole is preferably opened at a position where the bonding jig is inserted. 3 is a cross section of the pipe to be connected, 2 is a bonding jig sandwiched between the cylindrical core 1 and the pipe 3, and contains a substance that generates heat when irradiated with microwaves, and is made of the same material as the pipe. Formed by

FIG. 2 is a view of the assembled state of the pipe, the cylindrical core, and the bonding jig as viewed from above, and shows an example of the shape of a hole formed in the cylindrical core. When the bonding jig is melted by irradiating microwaves, confirm that the resin constituting the melted bonding jig comes out of these holes and that it has melted, and that the resin does not move due to bonding and cylindrical core Can be.

FIG. 3 is a perspective view showing the shape of the bonding jig. The inside of the jig is indicated by a dotted line. The inside is the same diameter as the outside diameter of the pipe, and the outside is inclined. It is shown that.

The bonding jig can be formed such that the inner diameter is smaller than the outer diameter of the pipe at the end having the smaller outer shape if necessary, so that the pipe and the bonding jig do not slip when the pipe is pushed in. By applying pressure to the bonding jig by the cylindrical core, the adhesion to the pipe can be further improved. When applying microwaves, it is more preferable to apply pressure from both ends of the pipe so that the bonding jig is brought into close contact with the bonding jig when it is melted by microwave irradiation.

A microwave is applied to the bonded portion assembled as shown in FIG. As a microwave, it can be heated to the extent that the thermoplastic resin is sufficiently fused with the wavelength and energy that are commercially available as a household microwave oven,
Microwaves having a frequency of several gigahertz (usually 2.45 gigahertz) can be used, and energy of about several KW / 1Kg is sufficient.

[0018]

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

EXAMPLE 1 15 g of acicular titanium oxide (anatase type, brand name NT-100) manufactured by Fuji Titanium Industry Co., Ltd. and Nippon Petrochemical Co., Ltd.
Made high-density polyethylene (brand name Staphlen E792) 1
5 g of Labo Plastomill R type (Toyo Seiki Seisakusho Co., Ltd.)
Was mixed well at 240 ° C. This operation was repeated to obtain about 100 g of the mixture. The mixture was pressed at 220 ° C. to form a wedge-shaped sheet having one thickness of 1 mm and the other thickness of 3 mm, with a width between 50 mm and a length of 300 mm.

A pipe having an outer diameter of 50 mm and a thickness of 5 mm and an outer diameter of 70 mm and a thickness of 1 are formed by extrusion molding using high-density polyethylene manufactured by Nippon Petrochemical Co., Ltd. (brand name: Staflen E801).
A pipe of 0 mm (inner diameter becomes 50 mm) was formed.
A pipe having an outer diameter of 70 mm was cut out by 100 mm, and the pipe was inclined and cut so that the inner diameter at the center (portion 50 mm from both ends) was 50 mm and the inner diameter at both ends was 56 mm, thereby obtaining a cylindrical core. 5 mm from the end of this cylindrical core
Four holes of 2 mm × 5 mm were formed. The above-mentioned sheet was tightly wound into a single layer and pressed into a cylindrical core so that the two pipes having an outer diameter of 50 mm were joined to each other so that a thin portion came to the end.

The assembly having the connection portion similar to that shown in FIG. 1 was put into a commercially available microwave oven (Toshiba Microwave Oven ERT-540F) and irradiated with microwaves for 8 minutes. At the time of irradiation, a rubber band was put into the pipe, the end of the rubber was taken out of the pipe, and both sides were stopped with a sheet of polyethylene having a thickness of 2 mm to push the pipe toward the center. When the bonded portion was cut into a circle and the state of bonding between the bonding jig and the pipe was observed, it was completely bonded.
Further, the composition comprising polyethylene and titanium oxide constituting the bonding jig protruded into the hole provided in the cylindrical core, and it can be seen that the bonding jig was sufficiently melted.

Example 2 Iron trioxide (Wako Pure Chemical Industries, Ltd.) was used instead of acicular titanium oxide.
The procedure was the same as in Example 1 except for the use of
Similarly, it was completely adhered.

[0023]

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 connecting portion of a pipe provided with a cylindrical core and a cylindrical bonding jig according to the present invention.

FIG. 2 is a plan view of a state where a pipe, a cylindrical core, and a cylindrical bonding jig are assembled, as viewed from above.

FIG. 3 is a perspective view showing the shape of a cylindrical bonding jig according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 Cross section of cylindrical core 2 Cross section of cylindrical bonding jig 3 Cross section of connected pipe 4 Through hole

Claims (2)

(57) [Claims] 1. A method of connecting a pipe made of a thermoplastic resin by irradiating microwaves using a cylindrical core provided in contact with an outer surface of the pipe at a connecting portion, wherein the cylindrical core is It is made of the same material as the pipe, and the inner diameter at both ends is larger than the outer diameter of the pipe, and the inner diameter is continuously narrowed inward, and has a through hole, and the same inner diameter as the outer diameter of the pipe And the outer diameter is at least larger than the minimum inner diameter of the cylindrical core, and the outer diameter of one end is larger than that of the other, and the outer diameter is cylindrical from the larger end to the smaller end. It is continuously reduced at the same rate of change as the inner diameter of the core, and contains a substance that generates heat when irradiated with microwaves. Connection pipes and irradiating the microwaves was inserted between types. 2. The method according to claim 1, wherein the substance which generates heat when irradiated with microwaves is acicular titanium oxide or iron trioxide.