JPH0326891B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field of the Invention) The present invention relates to a termite-proof heat-shrinkable tube used, for example, to prevent termite damage to buried plastic pipes, electric wire-cables, or their connections. (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 damage caused by termites, rats, bat 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 resistance to the electric wires and cables themselves, and (b)
It can be roughly divided into two types: providing termite protection around the area where electric wires and cables are installed. In other words, method (a) involves devising the structure and materials of the wires and cables, providing a layer containing termiticides, and applying termiticides, and method (b). One method is to apply anti-termite 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, deirdrin, and endrin were mainly used, but it has become clear that they are harmful to humans and animals and cause environmental pollution, and are now being used.
Its use is prohibited (Cabinet Order of October 2, 1981)
No. 302). Therefore, instead of using drugs, more and more measures are now 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 structure of the cable mentioned above, the wire-to-cable connection part must be independently treated for termites. That is, cable connections are usually covered with lead tape, which is highly effective against termites, but is not perfect. Therefore, applying an anti-corrosion tube containing an anti-termite material to the outermost sheath of the cable connection part is
Effective for complete termite prevention. 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 be safely and reliably coated over 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 is fixed, 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 plastic pipes, electric wires, cables, etc., the tube is heated to above its softening point or crystal melting point using a heating tool such as a gas burner or torch lamp, and the deformation strain frozen and fixed inside is eliminated. , almost recovers to its original shape. In order to impart termite-proofing properties to the heat-shrinkable tube as described above, a termite-proofing agent may be added to the thermoplastic resin composition used. Plastic containing extract of Cypress Naro wood as a thermoplastic resin composition that can be used for termite-proof heat-shrinkable tubes (Utility Model Publication No. 34623/1983)
Plastic containing 10% or more of creosote oil (Japanese Patent Publication No. 57-30787), PVC containing polyester plasticizer (molecular weight 3000 or more)
55-8810),

[Formula] X is Br m=1 to 4 Y is a C ₁ to C ₄ alkylidene group or A resin composition containing 5 to 50 parts by weight of one or more of the following compounds (Japanese Utility Model Publication No. 57-140016), mixed with fenitrothion, phoxim, or chlorpyrifos, and zinc octylate or zinc parsate, etc. PVC (JP-A-58-25012, JP-A-58-142927, JP-A-58-169810) and the like are known. The termiticide used in heat-shrinkable tubes for corrosion protection at electrical wire-cable connections must naturally have excellent long-lasting anti-termite effects, since plastic pipes and electrical wires-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. desirable. It is desirable that no blooming occurs even after molding. Excellent thermal stability is required even when heat-shrinking with a burner or the like during construction. Naturally, in the case of cable connections, it is undesirable for the mechanical properties, electrical properties, and other properties of the base material to be impaired after installation. However, there has not been a heat-shrinkable tube for corrosion protection that satisfies the above characteristics and contains a termiticide that is also excellent in termitproofing effects. (Disclosure of the Invention) As a result of various studies, the present inventors have discovered that a specific efficacy enhancer with excellent termite-proofing effects and low thermal decomposition properties especially at high temperatures can be used in plastic pipe materials or electric wire-cable joint materials. When blended with polyvinyl chloride resin (PVC), which is widely used in the industry, 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,
This is a termite-proof heat-shrinkable tube containing 3,3-tetrachloropropyl ether. The bis(2,3,3,3-tetrachloropropyl) ether (hereinafter referred to as the present compound) according to the present invention is available under the trade name S-421 manufactured by BASF. 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 it is contained in an amount of 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 a base resin for the thermoplastic resin composition, for example, in addition to PVC, polyolefins such as polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc. Union,
Alternatively, a composition containing chlorinated polyethylene or various other 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, chemical crosslinking or electron beam irradiation crosslinking is performed. When crosslinking PVC with electron beam irradiation, it is advisable to add 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 tube 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 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 effect, but also superior termite-proofing effects compared to those using other termiticides.
The following experiment shows that it has excellent electrical properties required for electric wires and cables. (Test termiticide) Table 1 shows the substances used as the test termiticide.

【table】
｜｜ ｜ ｜｜ ｜

Cl Cl HH Cl Cl
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. Anticide efficacy test (knockdown test) (a) Diluent: acetone drug concentration 0.1% and 1
%. (b) Test termites: Termite worker ants (c) Test method: 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] (Test sheet) PVC (degree of polymerization: approx. 1100-1300) 100 parts Plasticizer (phthalate ester) 50 parts Filler (heavy calcium carbonate) 30 parts Stabilizer (tribasic lead sulfate) From 5 parts The termiticide shown in Table 1 was mixed with a plasticizer into a PVC compound, mixed on a roll at 160℃ for about 10 minutes, taken out into a 1mm thick sheet, and further
Preheated at 160℃ for 10 minutes and pressed for 10 minutes,
A 13 cm x 17 cm sample sheet containing 3% termiticide was obtained. This 1 mm thick PVC sheet was covered on a 30 mm square pine sapwood, the overlapping portions and end portions 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,
The results are shown in Table 3.

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

[Table] 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, it was found that PVC containing 3%
Even a sheet with a thickness of 1mm was 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 an insulation resistance value of approximately 1/143 of that of a non-additive PVC sheet with 3% additive.
3 (a decrease of more than 3 digits), making it unsuitable as a corrosion-proofing material for electric wires and cables. In this regard, the present compound and fenitrothion are 0
The decrease is limited to ~2 digits, and the resistance of 10 ¹² Ω-cm, which is generally required as an anticorrosion material for electric wires and cables, can be maintained. (Tube extrusion test) A PVC compound with the same composition as the test sheet was extruded using an extruder as a tube material to obtain a tube, which was then crosslinked by electron beam irradiation.
This was heated to expand the diameter of the tube approximately twice, and while maintaining the expanded state, it was cooled to room temperature 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] (Unit: Survival rate %)
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 heat generation in the extruder, so the screw rotation speed must be reduced. First, the extrusion speed decreases, and the extrusion processing time increases, that is, the extrusion processing cost inevitably increases. On the other hand, a considerable proportion of the PVC compound to which this compound was added remained, indicating 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 the 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] 1. A termite-proof heat-shrinkable tube containing bis(2,3,3,3-tetrachloropropyl)ether.