JPS6053409B2 - Foamed polyolefin insulated wire - Google Patents

Description

Detailed Description of the Invention The present invention is a foamed polyolefin in which polyolefin or a copolymer resin mainly composed of polyolefin is coated with a foaming agent and a specific flame retardant on a conductor, and then foamed to a specific value and crosslinked by radiation. It relates to insulated wires.

Polyolefins, such as polyethylene, polypropylene, ethylene/vinyl acetate copolymer or ethylene/vinyl acetate copolymer
When making a polypropylene copolymer flame retardant, it is well known that an organic compound containing halogen or phosphorus or an inorganic compound such as antimony oxide is added as a flame retardant, and a combination of these two is used to make the polypropylene copolymer flame retardant. While improving the properties, it is common practice to modify the polyolefin itself by crosslinking it with radiation or the like to improve heat resistance properties and the like.

However, it is necessary to add a considerable amount of the flame retardant to obtain its effect, and as a result, there is a problem that the electrical properties of the insulator of the wire, especially the dielectric constant and volume resistivity, decrease. .

As a result of various studies conducted by the present inventors, it was found that when these compositions are foamed within a certain range of values, the electrical properties are close to those of polyolefin insulators that do not contain flame retardants, and the electrical properties are superior to unfoamed insulators. I found it.

That is, the degree of foaming of the insulator is in the range of 20 to 50%. That is, the gist of the present invention is to apply a blowing agent to a polyolefin or a copolymer resin mainly composed of the polyolefin on a conductor, and 10 to 10 parts of the polyolefin or this copolymer to 10 heel weight parts.
5 parts of trichloroethyl phosphate, tridibromopropyl phosphate, trilibenyl phosphate, perchloropentacyclodecane, phosphorus-containing polyol,
A foamed polyolefin insulated wire made of a composition containing a flame retardant selected from tribromophenyl acrylate or a flame retardant in combination with antimony trioxide, which has a foaming degree of 20 to 50% and is cross-linked by radiation. It is. Examples of polyolefins include low-density polyethylene/ethylene, medium-density polyethylene, high-density polyethylene, polypropylene, etc., and examples of copolymer resins mainly composed of polyolefins include ethylene/vinyl acetate copolymer, ethylene/polypropylene copolymer, etc. Such as merging.

In addition, as blowing agents, P,P-oxybis(benzenesulfonylhydrazide), trihydrazinotriazine,
Examples include azobisformamide, benzenesulfonyl hydrazide, and azodicarbonamide.

The blending amount of the flame retardant is 10 to 50 parts by weight per 10 parts by weight of the polyolefin.

In addition, the amount of the above-mentioned blowing agent is usually 100% of the polyolefin.
The amount is 5 to 15 parts by weight. Foaming is performed to make the electrical properties comparable to polyolefin insulators that do not contain flame retardants. As mentioned above, this foaming degree is 20 to 50.
It should be within the range of %. i.e. 20%
This is because a foaming degree of less than 50% cannot approach the dielectric constant of an insulator that does not contain flame retardants, and although it is better to have a higher foaming degree, it is difficult to achieve a foaming degree of 50% or more with chemical foaming agents. This is because. The insulator foamed in this area is then cross-linked by radiation.
Foaming forms a cross-linked insulator.

Next, examples of the present invention will be shown. Example A low density polyethylene composition having the following composition was heated at 160°C for 1
A foam sheet with a foaming degree adjusted to 40% was prepared under a pressure of 50 k9/al, and γ-rays of CO-60 were applied to it at 10 MRa.
d irradiation to produce foamed crosslinked polyethylene.

In addition, as a comparative example, low density polyethylene with the same composition except for the blowing agent was heated at 140°C and 150k9/c! 1 of pressure and crosslinked as before. The electrical properties of this sheet are shown in Table 1. Composition of low-density polyethylene composition Low-density PEIO weight part (Nippon Unica Co., Ltd., DFD-205) Chlorinated PE5 weight part (Showa Yuka Co., Ltd., Elastrene 401A) Dechlorane Plus-252 weight part Trioxide Antimony 1 rut area stabilizer
0. Calcium stearate, Antige Crystal
2 parts by weight tribromophenyl acrylate 5 parts by weight blowing agent 15
Parts by weight (Sankyo Chemical Co., Ltd., Selmaikou S) Example 1 The product of the experimental example was applied to a 0.4 order copper wire at 2.0Wr! coating to a thickness of n, then foaming by 40%, and further increasing the gel fraction to 8.
The electrical properties of an insulated wire cross-linked to 0% by radiation were measured.

As a comparative example, an unfoamed insulated wire was also measured in the same manner. The results are shown in Table 2.

The electrical properties and oxygen index of other flame retardants specified by the present invention were also investigated in the same manner as in the above examples, and the specific volume resistivity of the flame retardants according to the present invention was approximately 2 x 1015 Ω・α.
, dielectric constant (1σHz) 2.2-2. Sleeping dielectric loss approximately 2~
4 x 101, and an oxygen index of about 29 to 31, which is extremely excellent, while unfoamed flame retardant-added crosslinking has a volume resistivity (Ω・C7l) of about 2×1015 Ω・G, and a dielectric constant of 2.8.
~3.01 dielectric loss (103Hz) approximately 5~7×10−
4. The oxygen index was 30 to 33, the dielectric constant was slightly poor, and in the case where no flame retardant was added, the oxygen index was also very poor, and it was confirmed that it was inferior to the present invention.

Claims (1)

[Claims] 1. On the conductor, polyolefin or this copolymer is added with a blowing agent and 10 to 50 parts by weight of trichloroethyl phosphate, tridibromopropyl phosphate, triphenyl phosphate, or perchloropenta per 100 parts by weight of the polyolefin or copolymer. A composition containing a flame retardant selected from cyclodecane, phosphorus-containing polyol, tribromophenyl acrylate, or a combination of these and antimony trioxide is coated with a foaming degree of 20 to 50% and cross-linked by radiation. A foamed polyolefin insulated wire characterized by: