JP2527037B2 - Heat resistant polyolefin insulated wire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a crosslinked polyolefin insulated wire, and more particularly, to a polyolefin insulated wire capable of significantly improving heat aging resistance.

[Prior Art] Polyolefin has a number of suitable properties such as excellent electrical properties such as an electrical insulation pair and a dielectric constant, good mechanical properties, and excellent moldability.
Until now, it has been widely used as an insulating material and a covering material for electric wires and cables.

However, there is no problem, and one of them is a problem of oxidative deterioration. In other words, when used in the atmosphere, it gradually oxidizes and deteriorates due to the absorption of oxygen and shows brittleness, and in particular, deteriorates in a short time as its use temperature increases, lowering the mechanical strength, It is already well known that a reduction in flexibility and a reduction in electrical properties are caused.

Oxidation process of polyolefin is generally the oxidation initiation reaction,
It is considered that the progression reaction and the termination reaction are proceeding in combination, and in order to promptly carry out the termination reaction, a number of antioxidants have been proposed so far, and amine-based, phenol-based, Additives such as sulfur-containing compounds have been used alone or in various combinations.

[Problems to be Solved by the Invention] In recent years, the use temperature conditions of polyolefin insulated wires have become increasingly severe, and there are many cases in which use at higher temperatures is compelled. As additives useful at such relatively high temperatures, combinations of phenolic compounds and phosphite compounds, combinations of phenolic compounds and sulfur compounds, or combinations of amine compounds and sulfur compounds have been used so far. It is known to have a relatively large effect on improving characteristics. Then, various investigations have been conducted not only on the type but also on the combination ratio, the addition amount, etc. of these additives, and numerous proposals have been made for them as well, and they are sufficiently practical in the temperature range for ordinary purposes. It has been widely applied by those skilled in the art as a material that withstands.

The above-mentioned heat aging inhibitors, for example, have the drawback of discoloring polyolefins by adding them or inhibiting crosslinking, and also require insulation coating of electric wires of particularly high heat-resistant grade requiring higher heat aging characteristics. It is still not enough for use as a material. On the other hand, the demand for heat-resistant properties has become extremely high due to the miniaturization of equipment and the thinning of electric wires associated with the sophistication of equipment, and the demand for compositions that can withstand practical use under such conditions is increasing today. Although it is becoming increasingly stronger, the fact is that the type, combination ratio or amount of additives that can respond to such demands as a heat aging inhibitor have not been sufficiently studied and disclosed.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the object of the present invention is to significantly improve heat aging characteristics without coloring or bridging inhibition, particularly in wires and cables having a high heat resistance grade, and to be practically used in a high temperature region far exceeding a normal temperature range. It is intended to provide a heat-resistant polyolefin insulated wire which is possible.

[Means for Solving the Problems] The present invention relates to 100 parts by weight of polyolefin, tetrakis- (methylene-dodecyl-thio-propionate).
Methane and N, N ^- - hexamethylene bis - a (3,5-di -t- butyl-4-hydroxy-hydroxy raw bromide), the former and the latter ratio is 3: 2 to 3: is in the first range, and The composition is obtained by coating the composition added as an insulator in a total amount of 5.0 parts by weight or more and 15 parts by weight or less and crosslinking it.

The polyolefin used in the present invention is a homopolymer of α-olefin such as ethylene, propylene, butene-1, hexene-1, 4-methyl-pentene-1, or a random or block copolymer composed of two or more thereof. Yes, polyethylene, polypropylene, polybutene-1, polyisobutene, poly-3-methyl-butene-
1, poly-4-methyl-pentene-1, ethylene-propylene copolymer, ethylene-butene-1 copolymer, propylene-4-methyl-pentene-1 copolymer, propylene-butene-1 copolymer, Examples thereof include propylene-4-methyl-pentene-1 copolymer, decene-1--4-methyl-pentene-1 copolymer, and ethylene-propylene-butene-1 copolymer.

In the case of copolymerization, a polyunsaturated compound such as a conjugated diene or a non-conjugated diene or a compound containing acrylic acid, methacrylic acid, vinyl acetate or the like as a copolymerization component is also included together with the α-olefin. These polymers are acid-modified,
For example, a polymer graft-modified with an α, β-unsaturated fatty acid, an alicyclic carboxylic acid, or a derivative thereof may be used.

 Also, chlorinated polyethylene is included.

Further, in the present invention, an admixture obtained by adding a synthetic rubber, an inorganic filler, a flame retardant, and a polyfunctional monomer to these polyolefins can be used according to the application. The synthetic rubber that can be used in the present invention is ethylene-α
-Olefin copolymer rubber is preferred. Examples of the ethylene-α-olefin copolymer rubber include copolymer rubbers of ethylene and α-olefin, for example, propylene, butene-1, hexene-1, and the like.

However, as a wire covering material requiring particularly high heat resistance and crosslinkability, it is preferable to mainly use polyethylene, ethylene vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer.

 The above polyolefins may be blended with each other.

Although so many kinds as additives have been proposed, it tetrakis - (methylene - dodecyl - thio - propionate) methane and N, N ^- - hexamethylene bis (3,5
Di-t-butyl-4-hydroxy-hydrocinnamamide) combination should be selected. Next, the combination ratio must be in the range of 3: 2 to 3: 1 for the former and the latter. Thus, tetrakis- (methylene-dodecyl-
Thio-propionate) methane is always used in excess in the above range. Outside this range, heat resistance is reduced by half. Regarding the addition amount of both, the total amount of both should be 5.0 to 15 parts by weight with respect to 100 parts by weight of polyolefin. If it is less than 5.0 parts by weight, sufficient heat resistance cannot be obtained. If it is more than 15 parts by weight, blooming of additives, difficulty in kneading, and decrease in strength are caused. Preferably, the amount is 8.0 to 12 parts by weight.

By the above range, it has been found that a high degree of heat resistance that cannot be predicted from a conventionally known combination technology with a sulfur-based antioxidant and a phenol-based antioxidant is obtained, and the present invention has been completed. Is.

[Examples] Hereinafter, the present invention will be described with reference to Examples.

100 parts by weight of polyethylene (NUC ultra low density polyethylene,
Components such as those shown in Examples and Comparative Examples in Tables 1 and 2 were added to Nackflex, DFDA1137, MI = 0.8, d = 0.906, and the evaluation items shown in the lower column of each table were evaluated.

A test material composed of each component was kneaded with a 6-inch test roll, and the obtained composition was extrusion-coated using a 40 mm extruder to produce an electric wire having an insulation thickness of 0.5 mm.

Then, irradiation was performed with an electron beam at 20 Mrad to effect crosslinking.

The xylene-insoluble content in the evaluation items shown in Table 1 was determined by measuring the solid residue after extracting with xylene at 110 ° C. for 24 hours, and the coloring was visually determined. The heat aging characteristics were evaluated at a temperature of 200 ° C. using an ACR-UL oven manufactured by Toyo Seiki Seisaku-Sho, Ltd., with the number of air replacements being 200 times per hour.

 Table 1 shows the components of the test materials and the evaluation results.

The tetrakis- (methyle-dodecyl-thio-propionate) methane according to the present invention can be obtained as Synox 412S from White Calcium Co., Ltd., for example. Also N according to the present invention, N ^- - hexamethylene bis (3,5-di -
t-butyl-4-hydroxy-hydroxynamamide)
For example, Irganox 10 from Japan Ciba-Geigi Co., Ltd.
Available as 98.

The comparative additives used in Table 1 are Japanese Ciba
Irriganox 1010 (pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]) from Gaigi Co., Ltd., Irganox 1035 (2,2-thio-diethylenebis [ 3- (3,5-di-
t- butyl-4-hydroxyphenyl) propionate]), NOCRAC MB (2-(mercaptobenzimidazole of Ouchi Shinko Co.), Sumiraiza of Sumitomo Chemical Co., BBM-S (4, 4 ^- - butylidene - bis -(3-methyl-
6-tert-butyl-phenol), Nocrac 224 (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) from Ouchi Shinko Co., Ltd., DSTP (distearyl. Thiodipropionate), Irganox 1330 (1,3,5-trimethyl-, manufactured by Ciba-Geigy Japan, Ltd.)
2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene).

As is clear from Table 1, Example 1 shows that even under severe conditions of 200 ° C, which is considered to be beyond the limit for polyolefins.
It shows a remarkable heat resistance of 6.5 days. Considering that carbonization occurs in a few days when no additive is added, it can be seen that a remarkable effect of improving heat resistance is exhibited.

No. 1 of the comparative example is Seanox 412S and Irganox 10
There are 10 combinations, which are widely used as one of the best systems in the past. 1: 1 ratio or 1: 2 or 2:
Used in ratios such as 1, but in any ratio
It showed no heat aging properties for more than 3.5 days. The other relatively promising systems are far below the 6.5 day heat aging properties of Example 1.

Further, it is clear from the fact that xylene-insoluble matter does not inhibit crosslinking, and there is no problem of coloring contamination, and it can be clearly understood that it can be a composition suitable as an electric wire coating material.

Table 1 also teaches that the additives according to the present invention have no effect by either one alone, and it is necessary to add both within the range defined in the present invention.

Table 2 shows the results of evaluating the compounding ratio of the additives according to the present invention (Synox 412S and Irganox 1098 described above) and the relationship between the total addition amount and the heat aging resistance.

It can be said from Table 2 that if the total amount of both additives is increased within the range of the ratio of the present invention, the heat aging characteristics are further greatly improved. However, when the total amount added is close to 15 parts by weight, the effect is saturated and, conversely, problems occur in bloom and kneadability.
For the usage ratio, refer to the component code 412S: 1098 from 3: 2
Table 2 shows that a range of 3: 1 is extremely effective. For example, when 1098 is used in excess of 412S, the heat aging characteristics are greatly deteriorated as compared with the Examples as in Comparative Examples 12 to 17.

In addition to this, as Example 8, the same composition as in Example 3 was used except that dicumyl peroxide was further mixed in an amount of 1.5 parts by weight using a 40 m / m extruder at 130 ° C. on a tin-plated copper wire having an outer diameter of 0.8 mm. It was extrusion coated to a thickness of 0.8 mm and crosslinked by steam at 200 ° C. When a heat-resistant aging property was examined using a tube-shaped sample of an insulator of the electric wire, it showed a remarkable property of 10.0 days at 200 ° C.

The polyolefin according to the present invention is a filler other than the above,
There is no problem even if a lubricant, a processing aid, a flame retardant, a coloring agent or the like is added. In the case of cross-linking, it does not matter whether chemical cross-linking, radiation cross-linking or silane graft water cross-linking is used.

[Effects of the Invention] As described in detail above, according to the polyolefin insulated wire of the present invention, the heat aging characteristics can be dramatically improved, and in today's industry, insulated wires require high heat resistance. It is not an exaggeration to say that the industrial value possessed by the present invention is immeasurable, as the field of application is increasing.

 ─────────────────────────────────────────────────── --- Continued from the front page (56) References JP-A-50-67347 (JP, A) JP-A-55-118938 (JP, A) JP-A-59-188432 (JP, A) JP-A 61- 209241 (JP, A) Actually opened 64-54606 (JP, U)

Claims (1)

(57) [Claims] 1. Tetrakis- (methylene-dodecyl-thio-propionate) based on 100 parts by weight of polyolefin.
Methane and N, N ^- - hexamethylene bis - a (3,5-di -t- butyl-4-hydroxy hydrocinnamate raw bromide), the former and the latter ratio is 3: There is a 1 in the range: 2-3 A heat-resistant polyolefin insulated wire obtained by coating and crosslinking the composition added as an insulator in a total amount of 5.0 parts by weight or more and 15 parts by weight or less.