JPS61163517A - Antproof heat shrinkable tube - 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 (Technical Field of the Invention) The present invention relates to a termite-proofing heat treatment method used to prevent damage caused by termites to, for example, buried plastic pipes, electric wires and cables, or their connections. It concerns shrink tubing.

(Background of the Invention) Electric wires and cables are exposed to various usage conditions and environments, and their lifespan is usually determined by the electrical and mechanical deterioration of their jackets and insulators. Among these, many accidents have been reported in which electricity and communication suddenly become unavailable due to feeding damage from termites, rats, koramori moths, etc. with a frequency of 9 times.

In addition, termite damage also occurs to plastic pipes used for water or sewage.

Termite prevention methods for electric wires and cables can be basically divided into two types: (a) electric, although there are slight differences depending on the type of termites, environment, etc.

In other words, in method (a), the structure and materials of the wires and cables are devised, a layer containing termiticide is added,
Methods such as applying termiticides can be cited, and method (b) includes applying termite-proofing treatment to the soil along the installation route.

Among these methods, conventionally, from the viewpoint of processing the wires and cables and mainly from the viewpoint of cost, the method of adding a termiticide to the sheath material of the wires and cables has been most commonly adopted. In particular, so-called dorin-based drugs such as aldrin, dieldrin, and endrin were mainly used, but their use has now been banned as it has become clear that they are harmful to human stock and cause environmental pollution (1981 lθ Cabinet Order No. 302 of May 2nd).

Therefore, instead of using drugs, measures are now increasingly being taken from the viewpoint of structural design and material design.

That is, methods such as protecting the cable itself with a metal sheath or adding a coating layer such as nylon on the cable sheath are beginning to be adopted.

However, regardless of the cable structure mentioned above, the electric wire-cable connection section must be independently treated for termites. That is, cable connections are usually coated with lead tape or the like, which is highly effective against termites, but is not perfect. Therefore, applying an anti-corrosion tube containing an anti-termite agent to the outermost sheath of the cable connection part is effective in making the anti-termite properties more complete.

In particular, if the anti-corrosion tube is heat-shrinkable, it will be easier to apply the coating. That is, the heat-shrinkable tube can be heat-shrinked by simply heating it with a gas burner, torch lamp, etc. after being inserted into the cable connection part, and can completely and reliably cover the cable connection part.

Here, a heat-shrinkable tube is a tube molded product made of a thermoplastic resin composition that is expanded and deformed under heating and then cooled and solidified while maintaining the deformation strain.For example, it is made as follows. . A tube molded product made from a thermoplastic resin composition such as cross-linked polyethylene is heated to a temperature higher than its softening point or crystal melting point, and is expanded by applying an external force such as internal pressure. Cool to below melting point temperature. The deformation strain imparted to the tube by this operation becomes hard and chemotactic, and even if external forces such as internal pressure are removed, the tube hardly returns to its original shape and maintains its expanded shape. After inserting this into a plastic pipe, electric wire/cable, etc., the tube is heated to a temperature above its softening point or crystal melting point using a heating device such as a gas burner or a torch lamp, and the deformation strain frozen and fixed inside is eliminated. It will recover to its original shape.

To provide the heat shrink tube tζ termite resistance as described above,
A termiticide may be added to the thermoplastic resin composition used.

Thermoplastic resin compositions that can be used for termite-proof heat-shrinkable tubes include plastics containing extracts of Japanese cypress wood (Japanese Utility Model Publication No. 34623/1983) and plastics containing 10% by weight or more of creosote oil (Japanese Patent Publication No. 57/1986). −
30787), polyester plasticizer (molecular weight 3
PVC (Tokuko Sho 55-8810
A resin composition containing 5 to 50 parts by weight of one or more compounds represented by 01 to C4 alkylidene group or Br Br Br Br (Japanese Utility Model Application Publication No. 57-140016); PVC mixed with fenitrothion or phoxim or chlorpyrifos and zinc octylate or zinc persate (Japanese Unexamined Patent Publication No. 58-25012 or No. 58
-142927, JP-A-58-169810), etc. are known.

The anti-termite agent used in heat-shrinkable tubes for corrosion protection at the connections between electric wires and cables must have excellent long-lasting anti-termite effects, as plastic pipes, electric wires and cables are used for long periods of time. . In particular, volatilization during material mixing, tube extrusion, and expansion processing under heating is extremely low, and specifically, it has thermal stability even under conditions of several minutes to one hour at temperatures of about 160 to 220 degrees Celsius. is desirable. It is desirable that no pluming occurs even after molding. Excellent thermal stability is required even when heat-shrinking with a burner or the like during construction.

In the case of cable connections, it is of course undesirable for the mechanical properties, electrical properties and other properties of the base material to be impaired after installation.

However, there has been no anti-corrosion heat shrinkable tube that satisfies the above-mentioned properties and contains an anti-termiticide that is also excellent in anti-termite effects.

(Disclosure of the Invention) As a result of various studies, the present inventors have discovered that a specific efficacy enhancer that has excellent termite-proofing effects and has low thermal decomposition properties especially at high temperatures can be used in plastic pipe materials or electric wire-cable joint materials. When blended with widely used vinyl chloride resin (PVC), it was found that blooming did not occur, and based on this knowledge, the termite-proof heat-shrinkable tube of the present invention was completed. That is, the present invention provides bis(2, 3, 3,
This is a termite-proof heat shrinkable tube containing 3-tetrachloropropyl ether.

In addition, as bis(2,3,3,3-tetrachloropropyl)ether (hereinafter referred to as the present compound) according to the present invention, BA
There is a product name S-421 manufactured by SF.

In the present invention, the present compound is usually contained in the thermoplastic resin composition of the heat shrinkable tube in an amount of 0.01 to 10% by weight, preferably 0.05 to 5% by weight. Mixing with the resin can be carried out by conventional methods (for example, using calender rolls, Banbury, etc.).

In the present invention, as the base resin of the thermoplastic resin composition, for example, in addition to PvC, polyolefins such as polyethylene and ethylene-α olefin copolymer,
Compositions containing ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, chlorinated polyethylene, and other various synthetic rubbers to facilitate mixing of the present compound can be used.

After the thermoplastic resin composition is extruded to obtain a tube-molded product, it is subjected to chemical crosslinking or electron beam irradiation crosslinking. When crosslinking PvC by electron beam irradiation, it is preferable to mix a required amount of a polyfunctional monomer (for example, 2 to 10 parts by weight) in advance.

The thermoplastic resin composition may contain pigments, fillers, stabilizers, crosslinking agents, and the like, if necessary.

The crosslinked tube molded product is heated to a temperature higher than the softening point or crystal melting point of the resin composition to mechanically expand and expand the diameter of the tube molded product. Next, the expanded state is cooled to room temperature to obtain the heat-shrinkable tube of the present invention.

The termite-proof heat-shrinkable tube of the present invention, which is made by blending the present compound into the tube material, has not only superior termite-proofing effects but also the ability to meet the requirements for electric wires and cables, compared to tubes using other termiticides. The following experiment shows that it also has excellent electrical properties.

(Test termiticide) Table 1 shows the test termiticides used.

Table 1 No. Name Molecular formula 1%) Ether (this compound) Regarding the termiticide properties of the drugs themselves shown in Table 1, the following termicidal efficacy test was conducted, and the results shown in Table 2 were obtained. .

Anticidal efficacy test (knockdown test) (a) Dilution solvent: acetone drug concentration of 0.1% and 1%
And so.

(B) Test termites: House termites (C) Test method 2 Japanese termites countermeasures - The termiticidal properties of the drug were evaluated based on the mortality rate after 24 hours (25°C) in accordance with all specified methods. .

Table 2 (Unit: Mortality rate % after 24 hours) (Test sheet) PVC (Polymerization degree: approximately 1100-1300) 100
A PVC compound consisting of 50 parts plasticizer (phthalate ester), 30 parts filler (heavy calcium carbonate), and 5 parts stabilizer (tribasic lead sulfate) was mixed with the termiticide shown in Table 1 together with the plasticizer. , mixed on a roll for about 10 minutes at 180°C, 1
Take out u-thick sheet and preheat at 160℃ for 10 minutes.
Pressed for 10 minutes and added with termiticide 396.
An 8cInX 17α sample sheet was obtained. This 1jL
An IL-thick PVC sheet was coated on pine sapwood of 30 square meters, the overlapping part and the end part were completely sealed with adhesive tape with metal tape, and the sheet was subjected to a field test. Field tests were conducted for three years, and the results are shown in Table 3.

Table 3 Table 4 also shows the electrical properties (insulation resistance) of the PVC sheets obtained in the same manner.

First of all, it can be seen from Table 3 that Prothiophos has sufficient anti-termitic and anticidal properties as a drug itself, but in field tests, even PvC sheets with 396 added showed 1&IL.
The thickness has been penetrated. Therefore, even if it is mixed into electrical cable coatings, no anti-termite effect can be expected.

As shown in Table 4, chlorpyrifos has a 396-added Pv
The insulation resistance value of the C sheet decreased to about 1/1433 of that of the additive-free product (a decrease of more than 3 digits), making it unsuitable as a corrosion-proofing material for electric wires and cables.

In this respect, the present compound and fenitrothion only show a decrease of 0 to 2 digits, and can maintain the IQIIΩ value, which is generally required as an anticorrosion material for electric wires and cables.

(Tube extrusion test) A PVC compound with the same composition as the test sheet was extruded as a tube material using an extruder to obtain a tube, which was then crosslinked by electron beam irradiation and heated to approximately double the diameter of the tube. The tube was expanded and cooled to room temperature while maintaining the expanded state to obtain a heat-shrinkable tube. An appropriate amount of sample was taken from this heat shrink tube, and the remaining amount of the added termiticide in the PVC was determined. The results are shown in Table 5.

Table 5 (Unit: Residual Rate 96) As shown in Table 5, most of the added amount of fenitrothion decomposes and evaporates, making it impractical.

Although it is possible to improve the survival rate to some extent by lowering the material temperature during extrusion as much as possible, it is necessary to suppress the heat generation in the extruder, so the screw rotation speed must be reduced. As a result, the extrusion speed decreases and the extrusion time increases, which inevitably increases the extrusion cost. On the other hand, a considerable proportion of the PVC compound to which the present compound was added remained, and from this point as well, it can be seen that it is an extremely effective termiticide.

This compound does not cause blooming from the tube surface even after molding.

As mentioned above, the heat-shrinkable tube made of a thermoplastic resin composition containing this compound as an active ingredient not only has an excellent termite-proofing effect, but also has the ability to volatilize and decompose the termiticide during extrusion processing and heat shrinkage. are extremely rare.

Claims (1)

[Claims] A termite-proof heat-shrinkable tube containing bis(2,3,3,3-tetrachloropropyl)ether.