JPH0260964A - Tracking-resistant organic insulation material - Google Patents

Abstract

PURPOSE:To make it possible to markedly improve the tracking resistance of an organic insulation material by using a combination of magnesium with a metal carbonate as the anti-tracking agent. CONSTITUTION:100 pts.wt. polymeric material is mixed with 3-70 pts.wt. magnesium hydroxide and 2-30 pts.wt. metal carbonate. Examples of the polymeric material include polyethylene, an ethylene copolymer, an ethylene/propylene rubber, polyisobutylene and a butyl rubber. Examples of the metal carbonate include those of zinc, strontium, nickel, lithium, barium, calcium, magnesium, and cobalt.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to improvement of tracking-resistant organic insulating materials.

<Prior Art> In organic insulators used in salt-damaged areas and other type-contaminated areas, such as the insulation coating of electric wires, leakage current flows due to the adhesion of salts, dust, or moisture containing ionic pollutants, resulting in a joule drop. Due to the evaporation of adhering moisture due to heat, the leakage current path is disconnected and a discharge occurs at that point.The surface of the insulator is carbonized due to this discharge, and thereafter, due to the cumulative occurrence of carbonization, the carbonization path grows in a dendritic shape. The occurrence of a phenomenon known as tracking is unavoidable.

Therefore, tracking is unavoidable in -i rubbers and plastics due to their molecular structure, but tracking does not occur in inorganic materials, and conventionally, the trunking resistance of rubber and plastic insulating materials has been improved. It is known that inorganic powders are mixed in to improve
(better than aluminum hydroxide) exists.

<Problems to be Solved> However, even when this magnesium hydroxide is selected as the anti-tracking agent, the amount of anti-tracking agent added to 100 parts by weight of the polymer is usually 40 to 50 parts by weight, which is large in mold-contaminated environments. However, 70 parts by weight or more is required, which inevitably reduces the mechanical strength of the insulator.

However, an idea has been proposed in which the decomposition products generated by the discharge are allowed to escape from the insulator surface by, for example, gasification to eliminate the formation of carbonization paths, but this has not been put to practical use.

Under such circumstances, the inventors of the present invention conducted a study with the aim of improving the tracking resistance of the material for the edge of the machine case, and found that if a mixture of magnesium hydroxide and metal carbonate is used as an anti-tracking agent, the tracking resistance will be improved. I learned that it is possible to significantly improve

As mentioned above, magnesium hydroxide is a known anti-tracking agent. However, metal carbonate, such as calcium carbonate, generally makes little contribution to improving tracking resistance and is only recognized as a mere filler. However, according to the experimental results of the present inventors, a mixture of magnesium hydroxide and calcium carbonate can dramatically improve the trunking resistance compared to magnesium hydroxide alone, or significantly increase the amount added. It has become clear that this can be reduced. For example, the tracking resistance of a composition in which 3 parts by weight of magnesium hydroxide and 1 part by weight of calcium carbonate are added to 100 parts by weight of an EPDM base is as follows: The amount is equivalent to or more than that of the added composition.

The present invention is based on this unexpected finding and aims to dramatically improve the trunking resistance of organic insulating materials.

<Means for Solving the Problems> The anti-tracking organic insulation 1 according to the present invention contains 3 to 70 parts of magnesium hydroxide per 100 parts by weight of the polymer material.
It is characterized by containing 2 to 30 parts by weight of metal carbonate.

In the above, the amount of magnesium hydroxide added is 3 to 70
The reason for limiting it to parts by weight is that if it is less than 3 parts by weight, no practical effect of improving tracking resistance can be obtained even in the coexistence with metal carbonates, and if it is more than 70 parts by weight or more, the mechanical strength of the insulating material decreases. This is because it becomes noticeable. The reason why the amount of metal carbonate added was limited to 2 to 30 parts is that below 2 parts,
Synergistic improvement effect on tracking resistance due to the addition of the carbonate (synergistic effect due to mixing with magnesium hydroxide)
is not achieved satisfactorily, and if the amount exceeds 30 parts by weight, the mechanical strength of the insulating material will decrease significantly.

There are no particular limitations on the polymer material, but polyolefins such as polyethylene, ethylene copolymers, ethylene-brobylene rubber 11, polyisobutylene, butyl rubber, etc. are usually used.

There are no particular limitations on the above magnesium hydroxide, but
In order to ensure dispersibility in polymeric materials, it is desirable to perform surface treatment with fatty acids such as stearic acid and oleic acid, fatty acid metal salts, and the like.

As the metal carbonate, calcium carbonate, zinc carbonate, strontium carbonate, nickel carbonate, lithium carbonate, barium carbonate, carbonate, and further magnesium carbonate, cobalt carbonate, etc. can be used.

<Description of Examples> Examples of the present invention will be described below in comparison with comparative examples.

Example l Magnesium hydroxide (manufactured by Kyowa Chemical Co., Ltd., trade name: Kisuma 5B): 3 to 100 parts by weight of ethylene-propylene copolymer (manufactured by Mitsui Petrochemical Co., Ltd., trade name: EPT1045)
0 parts by weight, 10 parts by weight of calcium carbonate (heavy calcium carbonate manufactured by Maruo Calcium Co., Ltd.), and 1.5 parts by weight of dicumyl peroxide were added, mixed on a mixing roll, and heated at 160°C for 20 minutes. Press vulcanized under conditions,
Obtained an insulation sheet of 17.3 dragons.

Comparative Example 1 Same as Example 1 except that calcium carbonate was omitted.

Comparative Example 2 The same as Example 1 was used except that talc (talc manufactured by Asada Seifun Co., Ltd.) was used instead of calcium carbonate.

Tracking resistance tests A and B were conducted on these Example products and Comparative Example products under the following conditions.

Tracking Resistance Test A A test device compliant with ASTM, D, 2303 (slanted flat I-reverse method) was used. The surface of the sample was polished with sandpaper (silicone, carbide #420), and a specified amount of standard soil solution at a specified voltage was applied thereto to set a starting voltage of 3 KV, and the surface state of the sample was observed.

Tracking Resistance Test B The test equipment and method of dropping the staining liquid are the same as in the test. There is no sand in the soiling liquid! 1% mixed liquid is used, and the voltage application condition is 2K.
A constant voltage of V was applied, and the surface condition of the sample was observed after a predetermined period of time had elapsed.

The test results of Example 1, Comparative Example 1, and Comparative Example 2 are as follows.
As shown in the table. Therefore, in the tracking resistance test, in the case of Example 1, there was almost no erosion even when the voltage reached 5 KV or more, whereas in Comparative Examples 1 and 2, when the pressure was increased to 4 KV,
Burnt with KV.

In contrast to Trunking Resistance Test B, in Comparative Examples 1 and 2, combustion occurred 2 hours after electrification, whereas in Comparative Examples 1 and 2, there was only slight erosion even after 6 hours had passed after electrification. .

Comparative Example 3 The formulation was as shown in Table 1, and the results of tracking resistance tests A and B are shown in Table 1.

As is clear from the comparison between Comparative Example 3 and Example 1, Example 1 is superior in tracking resistance test B. Therefore, the addition of anti-tracking agent to the conventional product
With an addition amount of 40 parts (Example 1) compared to 40 parts (Comparative Example 3), it is possible to obtain an organic insulating material with excellent scratching resistance of 1 to 10 parts compared to the conventional product.

Examples 2 to 5 and Comparative Examples 4 and 5 The formulations were as shown in Table 2, and the results of tracking resistance tests A and B are shown in Table 2. Example 2 and comparative example 4
In contrast, according to the present invention, an insulating material with anti-tracking properties almost equivalent to that of the conventional product (Comparative Example 4) with an additive amount of 50 parts of anti-tracking agent can be obtained with an additive amount of 4 parts (Comparative Example 2). Can be done.

From Comparative Example 5, it is clear that when the amount of carbonate added is less than 2 polymerization parts, there is no synergistic effect (improvement in tracking resistance) with magnesium hydroxide.

Further, from the results of trunking resistance tests A and B in Example 5, it is clear that the present invention is useful for polyethylene, butyl rubber, etc. in addition to EPDM.

Examples 6 to 13 Ethylene-propylene terpolymer; 10 (1 part by weight, Magnesium hydroxide, 130 parts by weight of ram, dicumyl peroxide; 1.5 parts by weight, each metal carbonate as shown in Table 3) (all 10 parts by weight) part) was added.

The results of the tracking resistance tests A1 and B are shown in Table 3, and the effectiveness of each metal carbonate is clear.

<Effects of the Invention> As described above, according to the present invention, it is possible to provide an organic insulating material that has better tracking resistance than conventional products, or an organic insulating material that can reduce the amount of anti-tracking agent added. It is extremely useful for improving tracking resistance and mechanical strength of materials.

Table 1 Table 2 procedure correction building (spontaneous) 1999 March 1 day

Claims (1)

[Claims] 3 parts of magnesium hydroxide per 100 parts by weight of polymer material
-70 parts by weight, and a tracking-resistant organic insulating material characterized by containing 2 to 30 parts by weight of a metal carbonate.