JPS5846507A - Semiconductive polyolefin composition - 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 Including. ) This invention relates to improvements in semiconducting polyolefin compositions used in areas that come into contact with metals such as copper, such as semiconducting layers of insulated cables.

In high-voltage coolers using polyolefins such as polyethylene, crosslinked polyolefins, and ethylene proprene rubber as insulators, ethylene-prone rubber is used as a semiconductor layer.
The base material used is vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene propylene rubber, or a mixture thereof, to which carbon black is added to impart conductivity.

However, when in direct contact with copper conductors or copper tapes, moisture that enters during manufacturing processes such as steam crosslinking or during use can cause the copper to discolor or, in severe cases, corrode. In particular, carbon plectrum added to impart electrical conductivity tends to absorb moisture, and this tendency is more pronounced than in those to which no carbon black is added. Therefore, a method of coating with a compound such as benzotriazole has been adopted, but this increases the number of steps and is expensive.

There is also a method of adding a general-purpose copper damage inhibitor to a semiconductive compound, but it has the disadvantage that it is difficult to disperse because it generally has a high melting point.

The present invention has been made in view of the above, and its purpose is to discolor metals such as copper that are in contact with them,
An object of the present invention is to provide a semiconductive polyolefin composition that does not migrate to an insulator, contaminate the insulator, and deteriorate electrical characteristics.

The present invention is characterized by a semiconductive polyolefin composition in which 0.1 to 5 parts by weight of a liquid epoxy resin synthesized from bisphenol A and epichlorohydrin and having an epoxy equivalent of 280 or less is added to a semiconductive compound having an ethylene polymer as a base material. The point is that

4.4'-thiobis(6-ternyabutyl-m-cresol), 2.2'-thiodiethylbis-[:3-(3
, 5-di-tert-butyl-4-hydroxyphenyl)-propionate], °bendaerinurity-tetraquine (3-(3,5" di-tert-butyl-4-hydroxyphenyl) propionate) Even if sulfur-based or sulfur-containing phenolic antioxidants are added, they have no effect on preventing discoloration of copper that comes into contact with it.Additionally, even if these are combined with thioethers such as distearylthiodiglobionate, On the other hand, poly-2,
When an amine-based antioxidant such as 2,4-) dimethyl 1,2-dihydroquinoline is added, the anti-discoloration effect of copper is transferred to the insulator, contaminating the insulator, and causing damage due to flooding due to charging. It was confirmed that the breakdown voltage was reduced.

In contrast, epoxy resins with an epoxy equivalent of 280 or less, such as 2,2-bis(4-hydroxyphenyl)
Diglycidyl etherification product of propane with epichlorohydrin or 2-methylepichlorohydrin (trade name: Epicote 828 (Shell Chemical), Mark
It has been experimentally clarified that adding P-17 (Adeka Argus Chemical)) exhibits the effect of preventing copper discoloration and does not migrate to the insulator and contaminate the insulator. An epoxy resin with an equivalent weight of 280 or less is liquid and will be uniformly dispersed in the mixture when used, but an epoxy resin with an epoxy equivalent weight of 280 or more will become solid and will not be uniformly dispersed. In addition, the liquid state is advantageous in terms of handling such as measurement. Therefore, in the present invention, the epoxy equivalent is 280
The following liquid epoxy resins were used. Furthermore, if the amount of liquid epoxy resin added is 5 parts by weight or more, it will affect the physical properties of the semiconductive compound, and if it is less than 0.1 part by weight, the above-mentioned effects will be reduced. The amount was limited to 5 parts by weight. It was confirmed that this produced an effect of preventing copper discoloration and an effect of preventing insulator contamination, and also reduced the drop in breakdown voltage after electrification due to water immersion.

Furthermore, even if an antioxidant, a lubricant, a vulcanization aid, etc. are added, the effect of preventing copper discoloration is sufficiently maintained. However, the transition to the insulator may contaminate the insulator and degrade its electrical characteristics, so care must be taken in selecting it.

Examples and reference examples of the present invention will be described below.

Example 1 Ethylene-vinyl acetate copolymer (VA==, 19%, M
I=15') I00 parts by weight, 70 parts by weight of acetylene black, 0.3 parts by weight of 4,4'-thiobis-(6-tert-butyl-m-cresol), 20 parts by weight of dicumyl peroxide. was added, and 2.0 parts by weight of Epicoat 828 was added.

Example 2゜Ethylene-ethyl acrylate copolymer (EA amount = 18
%, MI=20), same amounts of acetylene black, antioxidant, and crosslinking agent were added as in Example 1, and 1.0 part by weight of Mark EP-17 was added.

Reference example 1゜ In Example 1, the addition of Epicote 828 was excluded.

Reference example 2゜ In Example 2Vc, addition of MarkEP-1 was excluded.

Next, the test methods and test results for the semiconductive compositions shown in Example 1.2 and Reference Example 1.2 will be explained.

(1) Copper discoloration test A copper wire was sandwiched between uncrosslinked sheets of a semiconductive composition about 2 cm thick, and after being remolded at a temperature below the decomposition temperature of the crosslinking agent,
After crosslinking in water vapor of 1'3 Kt/d for 15 minutes, it was left to stand at room temperature for 30 days, and at this stage the state of discoloration of the copper was observed.

(2) Insulator contamination test due to migration to insulator A sheet of semiconductive composition and a cross-linked polyethylene insulator sheet are placed one on top of the other, a load is applied so that they are in close contact with each other, and the mixture is placed in a constant temperature bath at 90°C for 2 hours. After leaving it for a week, the presence or absence of insulator contamination was observed.

(3) Breakdown voltage residual rate test after submergence voltage application Forming a semiconducting layer with each semiconducting composition
20-1 semiconducting layer thickness: 1 group, crosslinked polyethylene insulator thickness: 5.5 mm) was prototyped, crosslinking was performed using water vapor, and ACloKv was applied in water at 90°C.
After several days, the voltage application was stopped, the breakdown voltage was measured, and the residual ratio (%) with respect to the initial value was determined.

Table 1 shows the test results in the above test.

Table 1 As shown in Table 1, those using the semiconductive composition shown in Example 1.2 had no copper discoloration and no contamination of the insulator.
Therefore, the electrical characteristics of the insulator will not be deteriorated by corroding the copper.

The breakdown voltage residual rate after flooding is nearly 100%, and the drop in breakdown voltage is minimal. On the other hand, reference example 1
．． When the semiconductive composition shown in No. 2 was used, the results were unsatisfactory in terms of discoloration, copper discoloration, and residual percentage of broken mold.

According to the examples of the present invention, the above test results are obtained because epoxy resin has the effect of capturing organic acids, and organic acids such as acetic acid and acrylic acid generated from EVA and EEA during steam crosslinking are This is thought to be because it traps acids and also traps the decomposition residue of the crosslinking agent, which is an acidic substance.

Although cross-linked polyethylene insulators were used in the tests (2) and (3) above, cables using insulators such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate-v polyethylene propylene rubber, etc. A similar effect can be obtained in the case of

A similar effect can also be found in the case of non-crosslinked polyolefin insulated cables such as polyethylene.

As described above, the present invention has the effect of not discoloring metals such as copper that are in contact with the layer, or migrating to the insulator, contaminating the insulator, and deteriorating the electrical characteristics. .

Claims (1)

[Claims] A liquid material with an epoxy equivalent of 280 or less synthesized from bisphenol A and epichlorohydrin in a semiconductive compound based on ethylene polymer;
A semiconducting polyolefin composition, characterized in that the composition contains up to 5 parts by weight.