JPS61109996A - Method of joining water cross-linking type polyolefin pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a water-crosslinkable or water-crosslinked polyolefin pipe (hereinafter referred to as a water-crosslinked polyolefin pipe).
Regarding the joining method. More specifically, the present invention relates to a method for joining water-crosslinked polyolefin pipes that is easy to join and has high joining strength.

[Prior Art] Water-crosslinkable polyolefin pipes are usually joined by adhesion using a water-crosslinkable polyolefin adhesive. In order to obtain a strong bond using this method, it is necessary to sufficiently heat both the part of the pipe to be joined and the adhesive.

Therefore, water-crosslinked polyolefin pipes have conventionally been joined in the following manner.

As shown in Figure 2, pipe (1) and pipe (
A heating jig (5) into which the sleeve (Z) can be inserted is used to join the pipes (1), and the heating jig (5) is heated to, for example, about 250°C.
Heat the parts to be joined of 1) and sleeve (2). Next, use the heating jig (5) to once remove the pipe (1) and sleeve (2) and apply water-crosslinkable polyolefin adhesive to those parts to be joined. Then, the pipe (1) and the sleeve (21) are inserted into the heating jig (5) again to heat the parts to be joined.After the heating is finished, the pipe (1) and the sleeve (21) are inserted again. Remove the pipe (1) and sleeve (
2) and are fitted and joined.

[Problems to be Solved by the Invention] Conventional bonding methods have complicated procedures. In addition, if you do not strictly follow the established work standards, such as the time required for heating and adhesive application, as well as the procedure, the pipe may become deformed due to heat or the adhesive strength will be insufficient, making it impossible to obtain a good joint. Can not. However, in actual work sites, it is not always easy to strictly adhere to the work standards, which sometimes results in poor joining of pipes.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, an object of the present invention is to provide a method for joining pipes that is simple and reliable.

(Means for solving the problems) The method for joining water-crosslinked polyolefin pipes of the present invention is as follows:
An adhesive prepared by mixing a water-crosslinkable polyolefin adhesive with a polar material, a conductive material, or a ferromagnetic metal powder is applied to the parts of the pipe to be joined, the parts to be joined are brought into close contact, and then the parts to be joined are This method is characterized by heating and bonding using a high frequency heating method.

[Function] The joining method of the present invention is a method of adhesively joining the parts of pipes coated with a water-crosslinkable polyolefin adhesive by heating using a high-frequency heating method, and the joining method is performed using a conventional heating jig. This is an extremely simple method compared to the method of preheating.

In addition, water-crosslinkable or water-crosslinked polyolefins are
Whether it is pipes or adhesives, they are not heated by high frequency waves, or even if they are heated, they do not reach very high temperatures. Therefore, in the present invention, a polar material, a conductive material, or a ferromagnetic metal powder is mixed into a water-crosslinkable polyolefin adhesive, and the adhesive is made to be subjected to high frequency heating.

Therefore, according to the method of the present invention, heating only needs to be carried out once after the parts of the pipes to be joined are brought into close contact with each other, and since the parts to be heated are only the adhesive and a limited part of the pipe adjacent to it, heating The work is extremely simple and easy, and no thermal deformation occurs.

``Example'' Next, an example of the method of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram showing an embodiment of the joining method of the present invention.

In Figure 1, (1) is a pipe, (2) is a pipe (1
), (3) is an adhesive applied to the parts to be joined, and (4) is a high-frequency heating device for applying high-frequency heating.

The joining method of the present invention first involves connecting a pipe (1) and a sleeve (2).
), apply adhesive (3) to the pipe (1) and attach the sleeve (
Fit 2 together and make sure they stick together. The bonding is then carried out by heating the portion to be bonded using a high frequency heating device (4).

In the method of the present invention, a polar material, a conductive material, or a ferromagnetic metal powder is mixed into the polyolefin adhesive as described above for high frequency heating. They are the temperature required to obtain a strong bond with the adhesive, usually 140-3
There is no particular restriction as long as it can be heated to 00°C.

Typical polar materials include polyvinyl chloride,
Examples include chlorinated polyethylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethyl-acrylic acid copolymer, etc. Examples of conductive materials include carbon black, aluminum powder, copper powder, etc. Examples of the ferromagnetic metal powder include powders of iron, nickel, and cobalt.

The mixing ratio of these is 5 to 300 parts per 100 parts of the water-crosslinkable polyolefin adhesive (by weight, the same applies hereinafter);
The amount is preferably 20 to 200 parts, but is not limited to this range, and any blending ratio may be used as long as the necessary heating temperature is changed.

For example, if a polar material or a small amount of conductive powder is mixed in, it will be heated by high frequency dielectricity, and if a large amount of ferromagnetic powder is mixed in, it will be heated by high frequency dielectricity. In any case, the high-frequency heating method heats from the inside, so the temperature rises quickly and the necessary areas are heated uniformly, resulting in good adhesive bonding.

As the water-crosslinkable polyolefin adhesive used in the method of the present invention, conventionally used polyolefin adhesives having a hydrolyzable silane group in the main chain and/or side chain can be used as they are. . Examples of polyolefins include polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, and ethylene-vinyl acetate copolymer.
Examples include ethylene acrylate copolymer and chlorinated polyethylene.

Examples of water crosslinking accelerators include dibutyltin dilaurate, acetic acid box 18, stannous caprylate, and naphthene M.
A silanol condensation catalyst such as lead or zinc caprylate may be added in an amount of about 0.001 to 1 part per 100 parts of water-crosslinkable polyolefin.

Such water-crosslinkable polyolefin adhesives are applied to the parts of the pipe to be joined in a molten state or in the form of a solvent solution, or the adhesive is formed into a sheet or film and is wound or pasted on the parts to be joined. It will be worn. Thereafter, the parts of the pipes to be joined are brought into close contact and heated using a high frequency heating device.

The pipes may be joined by butt joining in addition to the sleeve joining described above.

In order to obtain a strong bond, it is desirable to heat the adhesive and its surroundings to a temperature that is about 20° C. or more, preferably about 50° C. or more higher than the melting point of the water-crosslinkable polyolefin used in the adhesive. For this purpose, in the case of dielectric heating, it is necessary to use a high frequency wave with a frequency of 10 to 508H7 for approximately 2 to 1
It only takes 20 seconds, and in the case of induction heating, frequency 1
It is sufficient to apply a high frequency of oO~500KH7 for about 1~10 seconds.

After high-frequency heating, applying pressure in the direction of inserting the pipe into the sleeve will improve the adhesion between the pipe and the sleeve, making the joint even stronger.

For example, 100 parts of water-crosslinkable polyethylene and ethylene-
An adhesive consisting of 80 parts of vinyl acetate and 0.02 parts of dibutyltin dilaurate was applied to the parts to be joined of the water-crosslinked Borie-ethylene vibrator and the water-crosslinked polyethylene sleeve, the two were fitted tightly together, and the high frequency of 408H7 was applied. Hold the pipe slightly further into the tube for 15 seconds,
After cooling, an extremely strong bond was formed.

[Effects of the Invention] The bonding method of the present invention is extremely simple because bonding can be performed with just two steps: applying an adhesive and applying high-frequency heating. This also makes it easier to comply with work standards at actual work sites, making it easier to perform reliable joining.

Furthermore, with high-frequency heating, it is extremely easy to control the heating temperature and heating time by the high-frequency heating device, and it is also possible to avoid heating parts other than the joint, which prevents joint defects such as I-stiffness that damage the pipe's surface shape. can also be avoided.

As described above, the joining method of the present invention has extremely high industrial applicability.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the joining method of the present invention, and FIG. 2 is an explanatory diagram showing a conventional joining method. (Drawing codes) (1): Water-crosslinked polyolefin pipe (3): Adhesive (4): High-frequency heating device I ¥1 Figure 1: Water-crosslinked polyolefin pipe

Claims (1)

[Claims] 1 A method for joining water-crosslinkable or water-crosslinked polyolefin pipes, wherein an adhesive containing a water-crosslinkable polyolefin adhesive mixed with a polar material, a conductive material, or a ferromagnetic metal powder is applied to the parts of the pipes to be joined. 1. A method for joining water-crosslinked polyolefin pipes, the method comprising coating the parts to be joined together, and then heating and joining the parts to be joined using a high-frequency heating method.