JPH07290575A - Connection of pipes - Google Patents

Abstract

PURPOSE:To easily connect pipes as an integral molded article by providing a cylindrical core made inwardly narrow in its inner diameter in a tapered state from both end parts thereof and provided with a thin-walled part at a connection part and inserting adhesive jigs having outer diameters made taper in the same way in the gaps between the core and pipes to irradiate them with a microwave. CONSTITUTION:The inner diameters of both end parts of a cylindrical core 1 having the same quality as pipes 3 are made larger than the outer diameters of the pipes 3 and made inwardly narrow continuously and thin-walled parts 4 are provided to the core 1 to observe such a state that a resin is heated until melted. Cylindrical adhesive jigs 2 composed of the same quality as the pipes are inserted in the gaps between the cylindrical core 1 and the pipes 3 to be irradiated with a microwave. The adhesive jigs 2 have an inner diameter same to the outer diameter of each of the pipes 3 and the outer diameter thereof is larger than the min. inner diameter of the cylindrical core 1 and made taper in the same way as the inner diameter of the core and the adhesive jigs 2 contain a substance generating heat by the irradiation with a microwave. The heat generating substance is needle titanium oxide.

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 by using a bonding jig having a specific structure. More specifically, it relates to a pipe bonding method using a bonding jig having a specific shape and a cylindrical core.

[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 with 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 an electromagnetic wave has the advantages as described above, but in actuality, in order to obtain sufficient heat generation, a large amount of a substance that absorbs an electromagnetic wave and converts it into heat is contained in the resin. Therefore, the fluidity of the layer in which the substance that generates heat by the irradiation of electromagnetic waves is dispersed and the portion that covers the layer are significantly different. Therefore, there is a problem in that it is difficult to form an integrally formed product.

[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 by using a cylindrical core provided in contact with the outer surface of the pipe at the connecting portion. The core is made of the same material as the pipe, the inner diameter of both ends is larger than the outer diameter of the pipe, and the inner diameter is continuously narrowed toward the inner side, and the core has a thin wall portion. , Has 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 end and is smaller from the larger end Towards the other end, the diameter decreases continuously with the same rate of change as the inner diameter of the cylindrical core, and it is made of the same material as the pipe and contains a substance that generates heat when irradiated with microwaves. Bonding jig is 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 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 condensation type engineering plastics such as styrene, vinyl chloride, methylmethacrylate, vinylidene chloride copolymers, polycarbonate, polyamide, polyester, polyether, polyetherketone, polyetheretherketone, polysulfone, polyimide, etc. Etc. may be anything.

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, as a substance that generates heat when irradiated with microwaves, any substance having such a property can be used. Specifically, titanium oxide and ferric tetroxide can be used. , Copper oxide, zinc oxide, and the like, and particularly preferably acicular titanium oxide and ferrosoferric oxide are used.

As the acicular titanium oxide, a commercially available acicular titanium oxide can be used. The acicular titanium oxide has a minor axis length of 0.01 to 10 μm and an aspect ratio of 5 to 1000, such as magnesium and calcium. It may be doped with another metal oxide, or may be doped with tin oxide, indium oxide, or the like to be conductive, or may be commercially available. The crystal form of titanium oxide may be either rutile type or anatase type, but it is necessary that the shape of fine particles is acicular. Commercially available iron trioxide is also available, and natural magnetite is pulverized, or iron is burned in air,
Examples thereof include iron (III) oxide reduced with hydrogen containing steam, and one synthesized by finely pulverizing red hot iron with steam applied. The particle size of such ferrosoferric oxide is 1000 μm or less, preferably 0.0
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 incorporating the substance which generates heat when irradiated with the microwave into the thermoplastic resin forming the cylindrical bonding jig, as long as it can be well mixed. Any method will do. For example, it is possible to mix a substance that generates heat when a polymer solution is irradiated with microwaves, mix well by a known mixing method such as a ball mill and a homogenizer, and then disperse the mixture, followed by molding and drying into the 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 or the like, then heated and melted and mixed with an extruder, a Brabender, etc., and then pelletized to form a bonding jig described later. Easy to do.

Here, the ratio of the thermoplastic resin and 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 in 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 that covers the pipe and is made of the same material as the pipe. Reference numeral 4 denotes a thin-walled portion provided on the cylindrical core, and the thin-walled portion is preferably provided at a position where the bonding jig is inserted. 3 is a cross section of the pipe to be connected, 2 is an adhesive jig sandwiched between the cylindrical core 1 and the pipe 3, and contains a substance that generates heat when irradiated with microwaves, and is of the same material as the pipe. Formed by.

FIG. 2 is a view of the pipe, the cylindrical core, and the bonding jig as seen from above, showing an example of the shape of the thin-walled portion provided on the cylindrical core. There is.
When the bonding jig is melted by irradiation with microwaves, the resin forming the melted bonding jig is heated and the resin forming the cylindrical core is also heated and melted. It can be seen by observing that when the protrusion as shown in FIG. 1 is provided in this thin portion, the protrusion bends or falls, so that it is more clearly heated until the resin melts.

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

In this bonding jig, the inner diameter is made 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 with the pipe can be improved. It is more preferable to apply pressure from both ends of the pipe when applying the microwave so that the bonding jig adheres well when melted by irradiation of the microwave.

The bonded portion assembled as shown in FIG. 1 is then irradiated with microwaves. As microwaves, it is possible to heat the microwaves to the extent that they are sufficiently fused with a thermoplastic resin at a wavelength and energy that are commercially available as household microwave ovens.
Microwaves with a frequency of several gigahertz (usually 2.45 gigahertz) can be used, and energy of about several KW / 1 Kg is sufficient.

[0018]

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

Example 1 15 g of needle-shaped titanium oxide (anatase type, brand name NT-100) manufactured by Fuji Titanium Industry Co., Ltd. and Nippon Petrochemical Co., Ltd.
High density polyethylene (brand name Staflen E792) 1
5g of Labo Plastomill R type (Toyo Seiki Seisakusho Co., Ltd.)
Product) and mixed well at 240 ° C. This operation was repeated to obtain about 100 g of a mixture. The mixture was pressed at 220 ° C. to form a wedge-shaped sheet having a thickness of 1 mm on the one hand and a thickness of 3 mm on the other hand, and a width between them of 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 were formed by an extrusion molding method using high-density polyethylene (brand name: Staflen E801) manufactured by Nippon Petrochemical Co., Ltd.
A 0 mm (inner diameter is 50 mm) pipe was molded.
A pipe having an outer diameter of 70 mm was cut out by 100 mm, and the pipe was cut by inclining so that the inner diameter of the center portion (a portion of 50 mm from both ends) was 50 mm and the inner diameters of both ends were 56 mm to obtain a cylindrical core. Four holes each having a diameter of 5 mm (opened until a thickness of 1 mm remained, not a through hole) were formed at four positions at a position of 8 mm from the end in this cylindrical core. The above sheets were tightly wound in a single layer and pushed into a cylindrical core so that two pipes each having an outer diameter of 50 mm were joined to each other so that a thin portion was formed at each end.

The thus-assembled connection part similar to that shown in FIG. 1 was placed in a commercially available microwave oven (Toshiba microwave oven ERT-540F manufactured by Toshiba) and irradiated with microwaves for 8 minutes. At the time of irradiation, a rubber band was put in the pipe, the ends of the rubber were taken out of the pipe, and both sides were fixed with a polyethylene sheet having a thickness of 2 mm so that the pipe was pushed toward the center. When the bonded portion was cut into slices and the bonding state of the bonding jig and the pipe was observed, it was completely bonded.
Also, when observing the holes provided in the cylindrical core, it can be seen that the thin portion of the cylindrical core is deformed and the resin portion forming the cylindrical core is also melted.

Example 2 Instead of acicular titanium oxide, iron tetraoxide (Wako Pure Chemical Industries, Ltd.)
Produced by the same method as in Example 1 except that reagents were used,
Similarly, it was completely bonded.

[0023]

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

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

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

[Explanation of symbols]

 1 Cross-section of cylindrical core 2 Cross-section of cylindrical bonding jig 3 Cross-section of pipe to be connected 4 Thin-walled part of cylindrical core

Claims (2)

[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 It is made of the same material as the pipe, the inner diameter of both ends is larger than the outer diameter of the pipe, and the inner diameter is continuously narrowed toward the inner side. It has the same inner diameter as the outer diameter, 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, which contains a substance that heats up when irradiated with microwaves, is continuously reduced at the same rate as the inner diameter of the cylindrical core. Connection pipes, characterized in that inserted between the tubular core and the pipe is irradiated with microwaves. 2. The method according to claim 1, wherein the substance that generates heat when irradiated with microwaves is acicular titanium oxide or ferrosoferric oxide.