JPS6116833A - Termite resistant heat-shrinkable tube - Google Patents

Abstract

PURPOSE:To enhance the termite resistant effect without causing blooming or the like, by incorporating a specified organic phosphorus agent that is less decomposed thermally at high temperatures into a vinyl chloride resin that will be used for a pipe material or the like. CONSTITUTION:The present termite resistant heat-shrinkable tube contains isopropyl=2-[ethoxy(isopropylamino)thiophospholyoxy]benzoate. An isophenphos represented by the formula is incorporated in an amount of 0.05-5wt% into a thermoplastic resin composition for the heat-shrinkable tube. The compound is mixed, for example, using a calender roll, Banbury, etc. Such a thermoplastic composition is extruded into a tube, and is crosslinked chemically or by means of an electron beam. Then the tube is heated to or over its softening temperature, the diameter is mechanically increased, and keeping that state, it is cooled to room temperature to obtain a heat-shrinkable tube.

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a termite-proofing heat treatment system 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 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 damage caused by termites, rats, kolamori moths, etc.

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

Although there are slight differences in termite prevention methods for electric wires and cables depending on the type of termites, environment, etc., the basic methods are (a) imparting termite-proofing properties to the electric wires and cables themselves, and (b) applying termite-proofing to the electric wires and cables. It can be roughly divided into two types: providing termite prevention to the area around the installation.

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, from the viewpoint of processing of electric wires and cables and mainly from the viewpoint of cost, the method of adding a termiticide to the sheath material of electric wires and cables has been most commonly adopted. In particular, so-called dorin-based agents such as aldrin, dieldrin, and endrin were mainly used, but their use has now been prohibited as it has become clear that they are harmful to humans and livestock and cause environmental pollution. May 2nd Cabinet Order No. 302).

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 connection parts of electric wires and cables must be independently treated for termites. That is, cable connections are usually covered with lead tape or the like, and although they are fairly termite-proof, they are not perfect. Therefore, it is effective to apply an anti-corrosion coating containing an anti-termite agent to the outermost sheath of the cable connection part in order to further improve the anti-termite properties.

In particular, if the anti-corrosion cheese 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, a cold lamp, etc. after being inserted into the cable connection part, and the cable connection part can be completely and reliably covered.

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. Made. 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 is fixed, and even when external forces outside the internal pressure are removed, the tube hardly returns to its original shape and maintains its expanded shape. After inserting this into plastic pipes, electric wires, cables, etc.
When the cheese is heated to a temperature higher than its softening point or crystal melting point using a heating tool such as a gas burner or a torch lamp, the deformation strain that has been frozen and fixed inside is eliminated, and the piece recovers to its original shape.

In order to impart termite-proofing properties to the above-mentioned heat-shrinkable cheese, a termite-proofing agent 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). −
3078'7), PVC containing a polyester plasticizer (molecular weight 3000 or more) (Japanese Patent Publication No. 55-8'8)
10), a resin composition containing 5 to 50 parts by weight of one or more compounds represented by an alkylidene group (Utility Model Publication No. 57-14.001)
6), PVC mixed with fenitrothion or phoxim or chlorpyrifos and zinc octylate or zinc persate (JP-A-58-25012 or JP-A-58-14-2927, JP-A-58-16)
9810) etc. are known.

The termiticide used in heat-shrinkable tubes for corrosion protection at the connections of 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. Specifically, it is desirable that the temperature be about 160 to 220°C for several minutes to one hour. Excellent thermal stability is required even when heat-shrinking with a burner or the like during construction. At the cable connection part, after it is installed,
Naturally, it is undesirable that the mechanical properties of the material, electrical properties, and other properties of the base material are impaired.

However, there has been no anti-corrosive heat-shrinkable tube containing a termiticide that satisfies the above-mentioned properties and also has an excellent anti-termite effect.

(Disclosure of the Invention) As a result of various studies, the present inventors have found that a specific organic phosphorus agent that has an excellent termite-proofing effect and has low thermal decomposition, especially at high temperatures, has been developed.
It was discovered that when blended with polyvinyl chloride resin (PVC), which is widely used in plastic pipe materials and joint materials for electric wires and cables, it does not cause pluming, etc. Based on this knowledge, the termite-resistant heat-shrinkable resin of the present invention Completed Cheeve. That is, the present invention provides isopropyl-2
-Anti-termite heat shrinkable tea containing [ethoxy(isopropylamino)thiophosphoryloxy]benzoate-
It is bu.

Benzoate is commonly referred to as isofenphos.

In the present invention, this isofenphos is used as a heat-shrinkable material.
It is usually contained in the thermoplastic/resin composition of 0.01 to 10% by weight, preferably 0.05 to 5% by weight.

Mixing with resin can be done by conventional methods (e.g. calender roll,
The method described by Bunbury et al.) can be used.

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,
It is possible to use a composition in which isofenphos is easily mixed by blending ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, chlorinated polyethylene, and various other synthetic rubbers.

After the thermoplastic resin composition is extrusion-molded to obtain a molded tube, chemical crosslinking or electron beam irradiation crosslinking is performed. When crosslinking PVC by electron beam irradiation, it is advisable to blend a required amount (for example, 2 to 10 parts by weight) of a polyfunctional monomer in advance.

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

The crosslinked chive molded product is heated to a temperature higher than the softening point or crystal melting point of the resin composition to mechanically expand the diameter of the chive 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 cheese of the present invention, which is made by blending isofenphos into a cheese material, not only has a higher termite-proofing effect than those using other termiticides, but also has excellent termite-proofing properties that are necessary for use in electric wires and cables. The following experiment shows that it also has excellent electrical properties.

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

Table 1 Number Name Molecular Formula 1 Formula % 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) Diluent: acetone drug concentration of 0.15% and 1
%.

(b) Test termites: Termite worker ants (c) Test method 2 The termiticidal activity of the drug was evaluated based on the mortality rate after 24 hours (at 25°C) in accordance with the method specified by the Japan Termite Countermeasures Association.

Table 2 (Unit: Mortality rate after 24 hours 96) pvc (degree of polymerization: approximately 1100-9=O=8) 1
00 parts plasticizer (phthalate ester) 50 parts filler (heavy calcium carbonate) 80 parts stabilizer (tribasic lead sulfate) 5 parts PVC compound was preheated at 160°C for 10 minutes to prevent termites shown in Table 1. , subjected to press processing for 10 minutes, termiticide 396
A 13an x 17cm sample sheet of the additive was obtained. This 1 mm thick PVC sheet is 30i.

It was coated on the corner pine sapwood, and the overlapping part and end part were completely sealed with adhesive tape with metal tape, and then 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.

Table 4 First, it can be seen from Table 3 that Prothiophos has sufficient anti-termitic and termiticidal properties as a drug itself, but in a field test, even a PVC sheet with 8% additive was penetrated through a 1 mm thickness. Oops. Therefore, no anti-termite effect can be expected even if it is mixed into electrical/cable coatings.

As shown in Table 4, chlorpyrifos has a 396-added PV
The insulation resistance value of the C sheet decreased to about 171433 compared to the additive-free product (a decrease of more than 3 digits), making it unsuitable as a corrosion-proofing material for electric wires and cables.

It can maintain 1O12Ω, which is generally required as an anti-corrosion material.

(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-shrinkable tube, and the remaining amount of the added termiticide in the PVC was determined. The results are shown in Table 5.

Table 5 (Unit: Survival rate %) However, by lowering the material temperature during extrusion as much as possible, it is possible to improve the survival rate to some extent, but in order to do so, it is necessary to suppress heat generation in the extruder, so it is necessary to reduce the screw rotation speed. This results in a decrease in extrusion speed and an unavoidable increase in extrusion time, that is, an increase in extrusion cost. On the other hand, most of the PVC compound to which isofenphos was added remained, and from this point as well, it can be seen that it is an extremely effective termiticide.

Infenphos does not cause blooming from the surface of the tube even after molding.

As mentioned above, the heat-shrinkable cheese made of a thermoplastic resin composition containing isofenphos as an active ingredient not only has an excellent termite-proofing effect, but also prevents the volatilization of the termite-proofing agent during extrusion processing and heat shrinkage. Decomposition is extremely low.

Claims (1)

[Claims] (1) A termite-proof heat-shrinkable tube containing isopropyl 2-[ethoxy(isopropylamino)thiophosphoryloxy]benzoate.