JPS5968345A - Resin composition - Google Patents

Abstract

PURPOSE:To provide a resin compsn. having excellent resistance to tracking and weather and useful for cables and cable terminals mainly for outdoor use, by blending magnesium hydroxide and iron oxide with a thermoplastic resin, rubber or a mixture thereof. CONSTITUTION:At least 20pts.wt. magnesium hydroxide and at least 4pts.wt. iron oxide are blended with 100pts.wt. thermoplastic resin such as ethylene/ propylene copolymer, rubber such as SBR or natural rubber, or mixture thereof with the proviso that thecombined amount of magnesium hydroxide and iron oxide does not exceed 200pts.wt., whereby the desired resin compsn. can be obtd.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a resin composition with excellent tracking resistance and weather resistance, and the present invention relates to an insulating composition for cables, cable terminals, etc. mainly used outdoors. It is used as a.

[Background of the invention]

Electric cables, cable terminals, connections, etc. that are installed outdoors for long periods of time and are exposed to wind and rain, etc., are exposed to wind and rain, seawater near the coast, and various electrolytes from exhaust air near factories adhere to them, causing discharge. occurs, and a carbonized conductive path is formed along the surface.

In order to prevent this, various efforts have been made to change the shape or mix the materials. For example, as an example of devising the compounding ratio, a large amount of filler is blended into resin or rubber, and rigid druggability is further improved by using hydrated alumina and oxides such as transition metals in combination. Efforts have also been made to improve it (Special Publication No. 50-15318).

On the other hand, although those used outdoors have good weather resistance, they are eventually discarded. With the exception of ceramic materials, organic insulating materials are susceptible to the effects of ultraviolet rays from sunlight and moisture from wind and rain. Generally, when used outdoors, a carbon blank is blended which is most effective in terms of weather resistance.

However, in general, when carbon black is added in a large amount, tracking resistance deteriorates, so it is difficult to strike a balance between the two. That is, in order to satisfy weather resistance and maintain tracking resistance, a large amount of filler has to be added, resulting in poor processability or sacrificing mechanical properties.

Furthermore, in recent years, requirements for anti-tracking properties have become even more stringent, and it is necessary to increase the amount of filler blended.
Processing is becoming more and more difficult over and over again.

In view of the above points, the present invention provides a resin composition and a composition having excellent tracking resistance and weather resistance.

[Summary of the invention]

The gist of the present invention is that 20 parts by weight or more of magnesila hydroxide J1 and 4 parts by weight or more of iron oxide are blended into a thermoplastic resin, rubber, or a mixture thereof, and the above magnesium hydroxide and the above iron oxide are blended. There is a resin composition characterized in that a total of 200 parts by weight or less of these substances is blended.

[Detailed description of the invention]

In the present invention, thermoplastic resins include homopolymers of olefins such as ethylene, ethylene-propylene copolymers, ethylene t"i'+: acid vinyl copolymers, ethylene ethyl acrylate copolymers, ethylene-(I' - In addition to ethylene copolymers such as olefin cothylamines, ethylene-propylene-dienenic polymers, salt-accumulated polyethylene, chlorosulfonated polyethylene, etc. are used.

-1-Foot Among the examples of thermoplastic resins, there are those that generally fall into the category of combs, but other types include silicone rubber, nitrile combs, fluororubber,
SBR, natural rubber, butyl rubber, chloroprene, etc. are used.

In the present invention, a mixture of the above thermoplastic resin and comb can also be used.

In the present invention, magnesium hydroxide is produced, for example, from bittern and slaked lime, pulverized, and then subjected to an appropriate surface treatment (for example, treatment with a fatty acid, a silane coupling agent, etc.).
The reason for specifying the blending amount to be 20 parts by weight or more is that it is particularly preferable because it has good dispersibility.
This is because if the amount is less than 0 parts by weight, little effect on 1liIJ tracking will be observed.

The iron oxide used in the present invention is Fe2O3 or Fe
The effect remains the same no matter which one, such as aO4, is the main ingredient.

The reason for specifying the amount of iron oxide in 4 parts by weight is as follows:
This is because if the amount is less than 4 parts by weight, little effect on weather resistance will be observed.

The maximum amount of magnesium hydroxide and iron oxide that can be blended varies significantly depending on the type of thermoplastic resin or rubber used, but the total amount of magnesium hydroxide and iron oxide is 200%.
When the amount exceeds the weight part, processing becomes difficult, for example, when blending with an ethylene-σ-olefin copolymer. and,
The higher the crystallinity of the resin, the lower the maximum blending amount tends to be. Therefore, the maximum blending amount cannot be determined uniformly, but is determined based on the difficulty of processing based on the type of thermoplastic resin or rubber.

As described above, the resin composition of the present invention is one in which magnesium hydroxide and iron oxide are used in combination, and by the combination thereof, the tracking resistance is improved more than before, and other weather-resistant pigments (such as titanium white We were able to achieve a significant improvement in weather resistance that cannot be achieved with TiO).

The present invention will be explained below using examples.

The formulations shown in Examples Tables 1 and 2 (Examples 1 to 7) were formed into sheets and exposed to an electron beam of 20 Mrad, and each of the obtained materials was tested for tracking resistance and A weather resistance test was conducted.

The results are listed in Tables 1 and 2.

(1) Tracking resistance test: ASTM D23
03, contaminated liquid (surfactant 0.1% Na (J
While flowing an aqueous solution containing 70.2% (70.2%) between the electrodes that were in contact with the sheet sample, the voltage between the electrodes was gradually increased, and the voltage at which tracking progressed was determined.

(11) Weather resistance test: A dumbbell-shaped sheet sample was punched out and left outdoors, and a tensile test was conducted after a certain period of time. If the elongation rate was 100% or more, it was considered to have passed. This standard serves as a guideline to ensure that normally insulated wires do not break when bent.

The same tests as in the Examples were also conducted for the formulations (Comparative Examples 1 to 8) shown in Tables 1 and 2 for ratio 1 bite cases.

(IU) ・IEVA (ethylene vinyl acetate copolymer); specific gravity 0.
95. MI (Melt Intex) 3, 2EEA (ethylene ethylene acrylate copolymer) containing 25% by weight of vinyl acetate)
Specific gravity 0.93, MI 6 , ethyl acrylate 18% by weight content-3EPDM, ML, 100°C: 50. Iodine value 10*4・LDPE (low density polyethylene); specific gravity 0.92°Mll, 2.5 average particle size 0.3/1. Surface area (BET) 107+
2. #=64.4'-thiobis(6-tert-butyl-8-methylphenol) *7 Average particle size 3.5/l (Note) *IEVAi specific gravity 0.95. MI3. vinyl acetate 25
Double notification: % content *2 Average particle size 0.37z + surface area (BET) to n
rz7p-3HAF, average particle size 23 mμ, surface area 72”
2/, F (N2 adsorption amount) *4.4・,4・′-thiobis(6-cushary-phthyl-3-methylphenol) From the comparison between the example and comparative examples 1 and 2, 20 parts by weight of magnesium hydroxide It can be seen that by blending the above two, the l-racking onset voltage becomes 4 KV or more, which is significantly improved compared to the one containing 50 parts by weight of aluminum hydroxide. In addition, regarding weather resistance, the resin composition of the present invention shows a significantly smaller degree of deterioration than the comparative example even after two years.

Comparing Example 2.7 and Comparative Examples 3 to 6, the effects of the present invention are even clearer. That is, the ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) compositions containing 4 parts by weight or more of iron oxide (Examples 2 and 7) had outstanding weather resistance, and were not exposed to the outdoors for many years. The change in elongation is also small. In contrast, the compositions containing titanium white (TiO2), which is said to be a pigment for improving weather resistance (Comparative Examples 14 and 5), showed a significant decrease in elongation due to outdoor exposure, and the effect of increasing the aging of titanium white was almost negligible. I can't admit it.

Furthermore, when a small amount of 2 parts by weight of iron oxide is added (Comparative Example 3), the service life ends after about 2 years due to outdoor exposure.

When carbon black was blended to improve weather resistance (Comparative Example 6, tracking performance deteriorated).

If the total amount of magnesium hydroxide and iron oxide exceeds 200 parts by weight, even if a relatively large amount of resin or rubber, such as an amorphous ethylene-α-olefin copolymer, is used, Mixing and processing were difficult, resulting in a composition with extremely poor mechanical performance, and there was no need to test for tracking resistance and weather resistance.

In the examples, electron beam irradiation crosslinking was performed, but the present invention is not limited to this, and for example, so-called chemical crosslinking using an organic peroxide or the like may be performed, and crosslinking may not be performed depending on the purpose.

Claims (1)

[Claims] (1) 20 parts by weight or more of magnesium hydroxide and 4 parts by weight or more of iron oxide are mixed into 100 parts by weight of a thermoplastic resin, rubber, or a mixture thereof, and the total of the above magnesium hydroxide and the above iron oxide is 200 parts by weight. 1. A resin composition characterized in that it is blended in an amount equal to or less than part by weight.