JPS628885B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a highly heat-resistant electrical insulation composition based on ethylene/α-olefin/polyene ternary copolymer rubber. Butyl rubber and ethylene/propylene rubber are widely used as electrical insulating materials with rubber-like elasticity, but because the physical strength of these polymers is low, they are reinforced with large amounts of inorganic fillers. Known examples of such inorganic fillers include talc, finely divided talc, clay, finely divided clay, silane surface-modified finely divided clay, calcium carbonate, finely divided calcium carbonate, magnesium carbonate, fumed silica, aluminum hydroxide, and silicate powder. It is being Among these, fine talc, fine clay, silane surface-modified fine clay, and fine calcium carbonate are used because the average particle size, particle size distribution, and dispersibility when blending pose problems for high voltage applications. These inorganic fillers are cheaper than the base polymer and have the advantage of reducing costs, but because they are blended in large quantities, it has been difficult to obtain materials with excellent heat resistance. On the other hand, the present inventors have discovered that certain ethylene, α-olefin, and
We conducted research on an electrical insulation composition with excellent heat resistance using polyene ternary copolymer rubber as a base polymer, and filed an application earlier.However, we also considered adding an inorganic filler to reduce the cost of this composition. It is not possible to obtain excellent heat resistance even by blending ordinary fine powder talc, fine powder clay, surface-modified fine powder clay treated with a silane coupling agent, etc., and only by blending a certain inorganic filler. It was discovered that a material with excellent heat resistance can be obtained. The present invention was made based on such knowledge, and consists of ethylene, an α-olefin having 4 to 10 carbon atoms, and a polyene at a polymerization molar ratio of ethylene/α-olefin of 80/20 to 95/5. Ethylene/α-olefin rubber copolymerized to contain a polyene component with an iodine value of 4 to 30, silicone modified fine powder clay of 10 to 60 PHR, anti-aging agent of 0.5 to 7 PHR, stabilizer of 5 The present invention provides a composition with excellent heat resistance and electrical insulation properties, which is characterized by containing ~40 PHR and crosslinking with an organic peroxide. Ethylene/α-olefin used in the present invention
Examples of polyene ternary copolymer rubber include a terpolymer of ethylene, 1-butene, and 5-ethylidene-2-norbolden, which is available as a product of Mitsui X-75 from Mitsui Petrochemical Industries, Ltd. It is marketed under the name The silicone surface-modified fine powder clay used in the present invention is a fine powder clay whose surface has been modified with silicone, and is manufactured by Burgess Pigment Co., Ltd.
It is commercially available under the trade name. The amount of this stuff is
10 to 60 PHR is appropriate; if it is less than this, the effect of reducing the price will be weak, and if it is more than this, the physical properties and heat resistance will deteriorate. Examples of anti-aging agents used in the present invention include 2-mercaptobenzimidazole or its derivatives, bis[2-methyl-4-{3-n-alkyl (C ₁₂ or ₁₄ ) thiopropionyloxy} 5-t-
butylphenyl] sulfide, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-S-triazine-2,4,6(1H.
3H, 5H) trione, 4,4'-bis(2,2'-dimethylbenzene)diphenylenediamine, and low-temperature reaction products of diphenylamine and acetone. These may be used alone or in combination of two or more if necessary. Stabilizers used in the present invention include zinc white, litharge, red lead, tribasic lead sulfate, basic lead sulfite, dibasic lead phosphite, and lead-barium compounds. Among these, a combination of zinc white and red lead or zinc white and resurge is preferred. In the present invention, the amount of anti-aging agent is 0.5~
The reason why the amount of stabilizer was limited to 5 to 40 PHR was as follows. In other words, if the amount of anti-aging agent added is less than 0.5 PHR or the amount of stabilizer added is less than 5 PHR, heat resistance will be insufficient; Amount is 40PHR
Even if the temperature is exceeded, the heat resistance improvement effect does not improve any further.
On the contrary, if the anti-aging agent is in excess, bleeding will occur, and if the stabilizer is in excess, the mechanical properties will deteriorate, which are both undesirable. The organic peroxides used in the present invention include di-t-butyl peroxide, di-t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butyl peroxy)hexane, 2,5-dimethyl-
2,5-di(t-butylperoxy)hexyne-
3,1,1-bis(t-butyl-peroxy)-
3,3,5-trimethyl-cyclohexane, n-
Butyl-4,4-bis(t-butylperoxy)
Valerate, etc., especially dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,
5-di(t-butylperoxy)hexyne-3 is preferred. In the present invention, sulfur, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, quinoid compounds, poly-P-dinitrosobenzene, etc. can be appropriately blended as a crosslinking aid together with the organic peroxide. . In the present invention, from the viewpoint of crosslinking efficiency, heat resistance, etc., the appropriate amount of organic peroxide is 1 to 5 PHR, and the amount of crosslinking aid is 0.1 to 7 PHR. In addition, other known additives may be appropriately blended into the composition of the present invention as long as the heat resistance is not reduced. The composition of the present invention is prepared by adding an antiaging agent and a stabilizer to the above-mentioned ethylene/α-olefin/polyene ternary copolymer rubber, kneading the mixture at a temperature of 60 to 90°C for 5 to 15 minutes, and then adding a crosslinking agent to the terpolymer rubber. After adding a crosslinking aid and kneading for 15 to 30 minutes, a predetermined molding process is carried out by a conventional method, and crosslinking is carried out by heating at 160 to 200°C for 15 to 30 minutes. The composition of the present invention obtained in this way is
It has excellent heat resistance, with both tensile strength and elongation remaining over 70% even after being heated in a constant temperature bath at 158°C for 168 hours. It also has excellent mechanical properties, and can be used as insulators for large-capacity power transmission high-voltage cables, insulators for motor lead wires and equipment wiring, etc., which require these properties.
It is also suitable as a cable insulator for nuclear power plants. Next, examples will be described. Example With the formulation shown in Table 1, Mitsui X-75, anti-aging agent, stabilizer and filler were first kneaded for 10 minutes on an open roll at 80°C, then cross-linking agent and cross-linking aid were added and mixed for 5 minutes. I kneaded it and took out the sheet. Next, this composition was applied using a frame plate with a thickness of 1 mm.
Crosslinking was carried out by heating and pressing in a press at 160°C for 30 minutes. Dumbbell samples according to JIS were punched out from the obtained sheet materials, and their characteristics were measured according to JIS. The measurement results are shown in Table 2.

[Table] The ingredients in Table 1 are as follows. MITSUI {3-n
-Alkyl (C ₁₂ or ₁₄ ) thiopropionyloxy}5-t-butylphenyl] sulfide Triam705 manufactured by Adeca Argus Chemical Co., Ltd. Triallyl trimellitate Vurges 5178 manufactured by Wako Pure Chemical Industries, Ltd. Silicone-modified clay Vurges manufactured by Burgess Pigment Co., Ltd. KE Silane-modified clay Translink clay #37 manufactured by Burgess Pigment Co., Ltd. Silane-modified clay Fresport Mistron vapor talc manufactured by Kaslin Fine powder talc White tex manufactured by Nihon Mistron Co., Ltd. Calcined clay

【table】

Claims (1)

[Claims] 1. Ethylene, an α-olefin having 4 to 10 carbon atoms, and a polyene in a polymerization molar ratio of ethylene/α-olefin of 80/20 to 95/5, and the iodine value is indicated. Ethylene/α-olefin rubber copolymerized to contain 4 to 30 polyene components is blended with 10 to 60 PHR of silicone improved fine powder clay, 0.5 to 7 PHR of anti-aging agent, 5 to 40 PHR of stabilizer, and organic peroxide. A highly heat-resistant electrical insulating composition characterized by being crosslinked with a material. 2 The anti-aging agent is 2-mercaptobenzimidazole or its derivative, bis[2-methyl-4-
{3-n-alkyl (C ₁₂ or ₁₄ ) thiopropionyloxy} 5-t-butylphenyl] sulfide,
1,3,5-tris(3,5-di-t-butyl-
4-hydroxybenzyl)-S-triazine-
2・4・6・(1H・3H・5H) Trion, 4・
Claim No. 1, characterized in that it consists of one or more selected from 4'-bis(2,2'-dimethylbenzene)diphenylenediamine and a low-temperature reaction product of diphenylamine and acetone. The highly heat-resistant electrical insulating composition according to item 1. 3. The stabilizer consists of one or more selected from zinc white, litharge, red lead, tribasic lead sulfate, basic lead sulfite, dibasic lead phosphite, and lead-barium compounds. A highly heat-resistant electrical insulating composition according to claim 1 or 2.