JP2857733B2 - Heat resistant crosslinked polyolefin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinked polyolefin composition useful as an electric insulating material, and more particularly to a heat resistant crosslinked polyolefin composition having excellent heat resistance, especially heat aging resistance.

[0002]

2. Description of the Related Art Polyolefin resins are widely used as various insulating materials because of their excellent electrical insulation properties and also excellent workability, water resistance and chemical resistance. However, since the heat resistance is not enough, in order to use it as an insulating material used in a high-temperature environment, for example, as an insulating coating material for heat-resistant electric wires, for example, irradiation with radiation or blending with an organic peroxide and heat-treating. Crosslinking has been used to increase the heat distortion temperature. However, even if the thermal deformation is suppressed by the crosslinking, it cannot be used for a long time unless the heat aging resistance is improved. Therefore, various attempts have been made to improve the heat aging resistance of the polyolefin resin.

In order to improve the heat aging resistance of such a polyolefin resin, a polyolefin polymer containing a benzimidazole compound and tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate is used. A method of blending an anti-aging agent (Japanese Patent Publication No. 4-504),
N, N'-di [diethyl-bis-3 (3,5-di-t-
Butyl-4-hydroxyphenol) propionate]
Oxamide and Benzimidazole Antioxidants and Pb
A method of blending one or two of O and ZnO (Japanese Patent Publication No. 5-1815), a method of blending zinc oxide, a benzimidazole-based antioxidant and a phenol-based antioxidant (Japanese Patent Laid-Open Publication No. No. 252246) has been proposed.

[0004]

However, the requirements for the heat aging resistance of polyolefin resins have become more and more severe, and these conventional techniques have not been able to sufficiently cope with them. Therefore, an object of the present invention is to provide a novel crosslinked polyolefin composition having further improved heat aging resistance.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
For 100 parts by weight of polyolefin, tris (3,5
- di -t- butyl-4-hydroxybenzyl) isocyanurate (A) and bis [2-methyl-4- {3-n-alkyl (C ₁₂ or C ₁₄₎ thio propionyloxy} -5
-T-butylphenyl] sulfide (B ₁ ) or decamethylene dicarboxylic acid disalicyloyl hydrazide (B ₂ )
A blend having a weight ratio of 95: 5 to 5:95 with respect to 0.5 to 15
Parts by weight, and 1 to 15 parts by weight of zinc oxide.

The polyolefin used in the heat-resistant crosslinked polyolefin composition of the present invention includes ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1, 3-methylbutene-1, and 4-methylpentene.
A homopolymer of an olefinic hydrocarbon monomer such as 1,
And copolymers of two or more of these monomers, for example, ethylene-propylene copolymers, ethylene-butene-1 copolymers, and the like, or these olefinic hydrocarbon monomers and a small amount of a vinyl ester monomer or (meth) Copolymer with acrylate monomer, for example, ethylene-
Vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, etc., and these various polymers can be used alone or as a mixture of two or more.

The amount of component (A) tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate used in the heat-resistant crosslinked polyolefin composition of the present invention is 100 parts by weight of the above-mentioned polyolefin. 4 for
Not more than parts by weight. If the amount exceeds 4 parts by weight, mechanical properties such as tensile strength of the composition will be reduced, and furthermore, a bleed phenomenon will occur and problems such as impairing the appearance of the product will occur.

The component (B) used in combination with the component (A) in the heat-resistant crosslinked polyolefin composition of the present invention comprises:
Bis [2-methyl-4-{3-n-alkyl (C ₁₂ or C ₁₄₎ thio propionyloxy} -5-t-butylphenyl] sulfide (B ₁₎ or decamethylene dicarboxylic acid disalicyloylhydrazide (B ₂ ), the amount of (B ₁ ) or (B ₂ ) used is in the range of 95: 5 to 5:95 by weight with respect to the component (A), preferably 9: 5.
The range is from 0:10 to 10:90. Outside this range, heat aging resistance is undesirably reduced.

The total amount of the components (A) and (B) used is 0.1 to 100 parts by weight of the above-mentioned polyolefin.
It is 5 to 15 parts by weight, preferably 1 to 10 parts by weight. The total amount of the components (A) and (B) used is 0.5
If the amount is less than 10 parts by weight, sufficient heat aging resistance cannot be obtained, and
Exceeding the parts by weight not only reduces the mechanical properties such as the tensile strength of the composition, but also causes problems such as bleeding of the component (B) and impairing the appearance of the product.

The amount of zinc oxide used in the heat-resistant crosslinked polyolefin composition of the present invention is 1 to 15 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the above polyolefin. If the amount of zinc oxide is less than 1 part by weight, the synergistic effect of the above components (A) and (B) is not sufficient, and excellent heat aging resistance is not exhibited.
If it exceeds 15 parts by weight, heat aging resistance is saturated, and
The mechanical properties deteriorate.

Further, bis [2-methyl-
4- {3-n- alkyl (C ₁₂ or C ₁₄₎ thio propionyloxy} when using -5-t-butylphenyl] sulfide (B _1), it is effective to blend talc. Such talc is a pulverized product of hydrous magnesium silicate or a calcined product thereof, and has an effect of suppressing the bleeding of the component (B ₁ ).
It is preferably 50 parts by weight or less based on 00 parts by weight. If the amount used exceeds 50 parts by weight, the mechanical properties and moldability will be significantly reduced.

[0012] The heat-resistant crosslinked polyolefin composition of the present invention may further contain various additives as necessary. Examples of such additives include antimony trioxide, inorganic flame retardants such as zirconium oxide, organic halogen-based flame retardants such as decabromodiphenyl ether, fillers such as talc, calcium carbonate, silica, and clay; and trimethylolpropane-trimethacrylate. Examples include a crosslinking assistant, a crosslinking agent such as an organic peroxide, and other antioxidants and lubricants.

The heat-resistant cross-linked polyolefin composition of the present invention comprises the above-mentioned components. The cross-linking is carried out by heating in the presence of an organic peroxide, by ionizing an electron beam or the like. A method of irradiating radiation can be used.

[0014]

The heat-resistant crosslinked polyolefin composition of the present invention comprises:
Due to the synergistic action of the component (A), the component (B) and the zinc oxide, extremely excellent heat aging resistance is exhibited.

[0015]

The density of the polyolefin is 0.924,
A low density polyethylene (LDPE) having an MI of 0.25;
Using a high-density polyethylene (HDPE) having a density of 0.949 and an MI of 0.30 and an ethylene-ethyl acrylate copolymer (EEA) containing 15% by weight of ethyl acrylate and having a MI of 0.75, (A ) ADK STAB AO-20 (Asahi Denka as component, a trade name), (B ₁₎ ADK STAB AO-23 (Asahi Denka as component, trade name), also (B ₂₎ Stab CDA-6 (manufactured by Asahi Denka as component, (Trade name), zinc oxide (ZO), antimony trioxide (FR1) and decabromodiphenyl ether (FR2) as flame retardants, talc (T) as an inorganic filler, and stearic acid ( S)
And trimethylolpropane trimethacrylate (TMPT) as a crosslinking aid were uniformly mixed by an open roll at 150 ° C. according to the composition shown in Table 1, and then press-formed at 175 ° C. to form a 1 mm thick sheet. Produced. Thereafter, crosslinking was performed by irradiation with an electron beam of 14 Mrad.

Each of the crosslinked sheets thus obtained is subjected to heat aging at 180 ° C. for 240 hours and 336 hours,
Table 1 shows the residual ratio of elongation after heat aging to initial elongation measured according to the method of JIS K6301. Also, the presence or absence of bleed was visually inspected, and ◎ when no bleeding occurred, 発 生 when slight bleeding occurred but there was no problem in appearance, and x when bleeding occurred. .

[0017]

[Table 1]

From these results, it can be seen that the heat-resistant crosslinked polyolefin composition of the present invention, in which the component (A), the component (B) and the zinc oxide are used in combination, has excellent heat aging resistance and little bleeding. I understand.

[0019]

The heat-resistant cross-linked polyolefin composition of the present invention is remarkably excellent in heat aging resistance, so that it is useful as an insulating material used in a high-temperature environment. A heat-resistant polyolefin electric wire that can be used continuously at a high temperature of 120 to 150 ° C. for a long time is obtained.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 23/00-23/36

Claims (3)

(57) [Claims] [Claim 1] With respect to 100 parts by weight of polyolefin,
Tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate (A) and bis [2-methyl-4
- {3-n-alkyl (C ₁₂ or C ₁₄₎ thio propionyloxy} -5-t-butylphenyl] sulfide (B
₁₎ or the weight ratio of decamethylene dicarboxylic acid disalicyloylhydrazide (B ₂₎ is 95: 5 to 5: formulation 95 and formulation 0.5 to 15 parts by weight of the zinc oxide 1-15 parts by weight A heat-resistant crosslinked polyolefin composition characterized by comprising: 2. Tris (3,5-di-tert-butyl-4-)
The heat-resistant crosslinked polyolefin composition according to claim 1, wherein the amount of (hydroxybenzyl) isocyanurate (A) is 4 parts by weight or less. 3. Bis [2-methyl-4- {3-n-alkyl (C ₁₂ or C ₁₄ ) thiopropionyloxy} -5-
t- butylphenyl] sulfide (B ₁₎ an effective amount of a by blending the talc according to claim 1 or 2 refractory crosslinked polyolefin composition.