JPH0925375A - Heat aging-resistant composition, and electric wire and cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. mainly comprising an ethylene-propylene rubber and improved in stability under heat without addition of a large amt. of an age-resister. SOLUTION: This compsn. consists of a base polymer comprising 100-30 pts.wt. ethylene/α/olefin copolymer of at most 0.88g/cm<3> in density obtd. by polymn. in the presence of a single site catalyst, and 0-70 pts.wt. ethylene- propylene rubber and/or ethylene/propylene/diene copolymer admixed therewith.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having excellent heat aging resistance, and an electric wire and a cable using the resin composition as an insulator.

[0002]

2. Description of the Related Art As a moving cable such as a cabtire cable, ethylene-propylene rubber (EPM) or ethylene-propylene-diene terpolymer (EPDM) is used.
It is known to have an insulator made of a resin composition in which an inorganic filler such as calcium carbonate and tarex, a cross-linking agent such as dicumyl peroxide, and the like are mixed. This is because ethylene-propylene rubber (EPM) and ethylene-propylene-diene terpolymer (EPDM) (hereinafter, these are collectively referred to as ethylene-propylene rubber in the present invention) have a low specific gravity and are lightweight. This is because it is soft and highly flexible, and has excellent electrical insulation and weather resistance.

By the way, a moving cable having an insulator mainly composed of such ethylene-propylene rubber is used.
When used in a high temperature environment exceeding 0 ° C., the insulator is required to have excellent high temperature heat aging resistance. In order to meet this requirement, it is possible to add a large amount of an antioxidant such as a phenolic antioxidant to a composition mainly composed of ethylene-propylene rubber. Inconveniences such as blooming (exudation) of the inhibitor, inhibition of ethylene-propylene rubber crosslinking, and deterioration of physical properties of the insulator occur. Further, the anti-aging agent is expensive, and there is a disadvantage that the unit price of the material increases.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to improve the heat aging resistance of a composition comprising ethylene-propylene rubber at high temperature, regardless of the increase in the amount of the antioxidant added. is there.

[0005]

Means for Solving the Problems This problem is obtained by polymerizing ethylene-propylene rubber by using a single-site catalyst and ethylene-α-having a density of 0.88 g / cm ³ or less.
The solution is to use a mixture of olefin copolymers as the base polymer of the composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The heat-aging-resistant composition of the present invention is an ethylene-α-olefin copolymer having a density of 0.88 g / cm ³ or less (hereinafter, single-site copolymer) polymerized with 0-70 parts by weight of ethylene-propylene rubber and a single-site catalyst. A base polymer consisting of 100 to 30 parts by weight, and if necessary, an inorganic filler, an antioxidant, a softening agent, a cross-linking agent, a cross-linking aid and the like are added to the base polymer Is. In addition, the electric wire and cable of the present invention have their heat insulating and aging composition formed as an insulator.

As the ethylene-propylene rubber, one which has been conventionally used in the electric wire coating field is used, and either ethylene-propylene rubber (EPM) or ethylene-propylene-diene terpolymer (EPDM) is used. Can be used alone or in combination. When these are used in combination, the quantitative ratio of the two is not particularly limited. In the present invention, an ethylene-propylene-diene copolymer (EPD) which is particularly easy to crosslink.
M) is preferable, and among them, the Mooney viscosity is 20 to 70.
It is preferable to use an insulating material having a low viscosity because the compression restitution property is improved.

The single-site copolymer according to the present invention is a copolymer of ethylene and α-olefin which has a narrow molecular weight distribution and a narrow composition distribution in which active species are polymerized by using one special organometallic catalyst. It is a polymer. As the α-olefin here, propylene, butene, pentene, octene-1 and the like are used, and the mole fraction of the α-olefin in the copolymer is in the range of 5 to 20%. As this copolymer, one having a density of 0.88 g / cm ³ or less is used. A single-site copolymer having a density of more than 0.88 g / cm ³ lacks flexibility, and is not easily used as an insulator. This is disadvantageous because the flexibility is reduced and the weight is increased to reduce the mobility.

A preferred specific example of this single-site copolymer is an ethylene-octene-1 copolymer having a density of 0.868 g / cm ³ ("ENGAGE CL80".
01 ”product name, manufactured by Dow Chemical Company). The mixing ratio of the single site copolymer and the ethylene-propylene rubber is 100 to 30 for the single site copolymer.
The ethylene-propylene rubber is added in an amount of 0 to 70 parts by weight per part by weight. If the amount of the single-site copolymer is less than 30 parts by weight, the effect of improving the heat aging resistance cannot be obtained.

If necessary, an inorganic filler is added to the heat aging-resistant composition mainly containing a base polymer composed of such a single-site copolymer and ethylene-propylene rubber. Well-known calcium carbonate, talc, diatomaceous earth, clay, mica, etc. are used as the inorganic filler, and those which have been surface-treated with a fatty acid such as stearic acid in advance in consideration of dispersion in the base polymer are preferable. The blending amount of this inorganic filler is in the range of 80 to 200 parts by weight with respect to 100 parts by weight of the base polymer, but it may be other than this depending on the application.

The heat aging-resistant composition of the present invention may be crosslinked. For this purpose, 3 to 10 parts by weight of a crosslinking agent composed of an organic peroxide such as dicumyl peroxide is added to 100 parts by weight of the base polymer. Further, in order to accelerate the crosslinking, 5 to 15 parts by weight of zinc dimethacrylate, triacyl isocyanurate or the like can be added as a crosslinking aid to 100 parts by weight of the base polymer.

Further, in the heat aging-resistant composition of the present invention, an antioxidant may be added in order to further improve the heat aging resistance. In this anti-aging agent,
Phenol-based antioxidants such as 4,4′-thiobis- (3-methyl-6-t-butylphenol) are mainly used, but thio-based and phosphorus-based antioxidants can also be used. The amount of the antioxidant added is preferably in the range of 0.3 to 3 parts by weight with respect to 100 parts by weight of the base polymer, and a compounding amount exceeding 3 parts by weight is useless, and the adverse effect of adding a large amount is disadvantageous.

In the heat aging-resistant composition of the present invention, a softening agent may be added to further enhance the flexibility of the insulating material. Paraffinic oil or the like is used as the softener, and the softener is 5 to 20 parts with respect to 100 parts by weight of the base polymer.
It is added in the range of parts by weight. Further, carbon black, an ultraviolet absorber, a flame retardant and the like can be added as required.

Specific examples of the compounding agent for the heat aging-resistant composition of the present invention include the following. Ethylene-octene-1 copolymer 45-55 parts by weight Ethylene-propylene-diene copolymer 55-45 parts by weight Inorganic filler 90-120 parts by weight Softener 3-8 parts by weight Anti-aging agent 0.5-1 part by weight Part Cross-linking agent 3-5 parts by weight Cross-linking aid 8-12 parts by weight

In such a heat aging resistant composition,
Since the thermal stability of the single-site copolymer is extremely good, the heat aging resistance, particularly the heat aging resistance at a high temperature of 120 ° C. or higher, becomes good without adding a large amount of the antioxidant. Further, since it is rich in flexibility, it has good flexibility when used as an insulator, and since it has a low density, it is lightweight and the cable can be handled easily. Further, since the amount of the antioxidant to be added is small, the disadvantages such as blooming, inhibition of crosslinking and deterioration of physical properties due to the addition of a large amount of the antioxidant do not occur.

Hereinafter, the working effects will be clarified by showing concrete examples. The composition having the composition shown in Table 1 was used for 150
The mixture was kneaded at 0 ° C. and extruded into a sheet to prepare a test sheet, which was heated at 200 ° C. for 10 minutes to crosslink. This sheet was subjected to elongation at break, heat aging resistance, and bending test. The heat aging resistance is measured at 135 ° C, 150
The elongation before and after heating of the sheet heated at 168 ° C. and 160 ° C. was measured, and the result was expressed by the residual rate (%). Also,
The bending test was performed according to JIS-C-3005. The results are shown in Table 1.

[0017]

[Table 1]

In Table 1, * 1 ethylene-propylene-diene copolymer ("EP
T3045 ", trade name, manufactured by Mitsui Petrochemical Co., Ltd. * 2 Ethylene-propylene rubber (" EPT004 "
5 ”, trade name, manufactured by Mitsui Petrochemical Co., Ltd.) * 3 Ethylene-octene-1 copolymer, density 0.86
8 g / cm ³ (“ENGAGE CL8001”, trade name, manufactured by Dow Chemical Co.). From the results in Table 1, the composition of the present invention is especially 150
It can be seen that the heat aging resistance at a high temperature of up to 160 ° C is extremely excellent.

[0019]

As described above, the heat aging-resistant composition of the present invention has excellent heat aging resistance especially at high temperatures. Therefore, an electric wire or cable having an insulator made of this heat aging-resistant composition also exhibits excellent heat resistance. Further, in this composition, the single-site copolymer is cheaper than the ethylene-propylene rubber, and the amount of the high-temperature antioxidant used is small, so that the composition can be obtained at low cost. Further, it is possible to prevent blooming, crosslinking inhibition, and deterioration of physical properties due to the addition of a large amount of antiaging agent.

Claims (2)

[Claims] 1. A density 0.88 obtained by polymerizing an ethylene-propylene rubber and / or an ethylene-propylene-diene copolymer with 0 to 70 parts by weight by a single-site catalyst.
g / cm ³ or less ethylene-α-olefin copolymer 1
A heat aging resistant composition comprising a base polymer mixed with 0 to 30 parts by weight. 2. A wire or cable comprising the heat-aging composition according to claim 1 as an insulator.