JPH04334811A - Flame retardant electric insulating composite - Google Patents

Abstract

PURPOSE:To provide a flame retardant electric insulating composite to prevent the generation of a poison gas in the combustion, and to furnish an abrasion resistance, an oil resistance, and a flame resistance, as to a flame retardant electric insulating composite used as an insulator of a power line or a cable. CONSTITUTION:In an ethylene-vinyl acetate copolymer including the vinyl acetate 20wt.% or more, or in a polymer mixed to include the vinyl acetate 20wt.% or more, 50 to 100 pts.wt. of a metal hydroxide a surface treatment by vinylsilane or aminosilane has been applied is mixed to 100 pts.wt. of the polymer, and furthermore, a calcium system compound Ca(OOCR)n (R is an alkyl group, and n is a natural number) is added at least 0.5 pts.wt. or more.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a flame-retardant electrical insulation composition used as an insulator for electric wires and cables, and in particular,
This invention relates to a flame-retardant electrical insulating composition that prevents the generation of toxic gases during combustion and has wear resistance, oil resistance, and flame retardancy.

0002

[Prior Art] Flame-retardant electrical insulation compositions used as insulation coatings for electric wires, cables, etc. are generally made of polyvinyl chloride or halogen-based flame-retardant cross-linked polyethylene to minimize the spread of fire in the unlikely event of a fire. Flame retardant materials such as chloropropylene rubber and the like are often used. However, when these flame-retardant materials are burned, they release a large amount of highly toxic halogen-based gas and also emit a large amount of smoke, so there is a concern that damage may be amplified. Furthermore, when this flame-retardant material is incinerated, it may generate harmful dioxins and cause environmental pollution. For this reason, non-halogen flame retardant materials that incorporate metal oxides are attracting attention as a flame retardant material that does not have these drawbacks.

0003
.

[Problems to be Solved by the Invention] Recently, the development and practical application of this non-halogen flame retardant material has been vigorously promoted in various fields, and one of them is that it has flexibility comparable to chloroprene rubber, and There is a growing demand for materials with excellent wear resistance, oil resistance, and flame retardancy.

By the way, in order to impart the desired flame retardancy, it is necessary to mix a large amount of metal hydroxide into the polymer, but as a result, the required flexibility and abrasion resistance are significantly impaired. There was a problem with putting it away.

Therefore, the present invention was devised to effectively solve the above-mentioned drawbacks, and its purpose is to have the flame retardancy of the conventional one, excellent flexibility, wear resistance,
An object of the present invention is to provide an electrical insulating composition with good oil resistance.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an ethylene vinyl acetate copolymer having a vinyl acetate content of 20% by weight or more, or a polymer blended so that the vinyl acetate content is 20% by weight or more. Inside, the polymer 1
00 parts by weight, 50 to 300 parts by weight of metal hydroxide surface-treated with vinylsilane or aminosilane are mixed, and calcium-based compound Ca(OOCR)n (
R is an alkyl group and n is a natural number) at least 0.5 part by weight.

In the present invention, ethylene vinyl acetate copolymers or other polymers such as polyethylene, ethylene ethyl acrylate copolymers, ethylene methyl methacrylate copolymers, ethylene propylene rubber, ethylene butene copolymers, ethylene butene terpolymers, etc. or ethylene with different vinyl acetate contents can be used. Vinyl acetate copolymers can be used as a blend, but in any case the vinyl acetate content must be 20% by weight or more based on 100% of the polymer. That is, if it is less than 20% by weight, flexibility will be impaired and oil resistance will be significantly reduced.

[0008] Then, 50 to 300 parts by weight of a metal oxide surface-treated with vinylsilane or aminosilane is mixed with 100 parts by weight of such polymer. That is, the present inventors have found that by surface-treating the metal oxide used with vinylsilane or aminosilane, the affinity of the metal hydroxide is significantly improved, and the wear resistance and oil resistance are improved.

Examples of the vinyl silane include CH2
=CHSi(OCH3)3, CH2 =CHSi(
OC2 H5 ), CH2 = CHSi(OC2 H4
Examples of aminosilane include NH2 C3 H6 Si(OC2
H5)3, NH2C2H4NHC3
H6Si(OCH3)3,NH2CONHC
3 H6 Si(OC2 H5 )3 is a typical example. This surface treatment may be carried out by either a dry method using a Henschel mixer or the like or a wet method in which treatment is carried out in a slurry, but the wet method provides a product with higher performance. Although the amount of surface treatment is not particularly specified, it is desirable to add at least an amount that forms a monomolecular film on the surface of the metal hydroxide.
It is necessary to add it in a range of 1 to 3 parts by weight per 0 parts by weight.

[0010] As the metal oxide, aluminum hydroxide,
Magnesium hydroxide, magnesium carbonate, calcium aluminate, etc. may be used alone or in combination, but the amount to be mixed is 50 to 3 parts by weight per 100 parts by weight of the polymer.
00 parts by weight. That is, if the amount of the mixture is less than 50 parts by weight, the desired flame retardance cannot be imparted, and if the amount of the mixture exceeds 300 parts by weight, the flexibility and abrasion resistance will be significantly lowered.

[0011] Calcium-based compound is Ca (OOCR)
n (R is an alkyl group, n is a natural number), and examples include calcium laurate, calcium ricinoleate, calcium hydroxystearate, and calcium stearate. The amount of this calcium-based compound added is at least 0 per 100 parts by weight of the polymer.
．． It is necessary to add 5 parts by weight or more, and if the amount of the calcium-based compound added is less than the limited value (0.5 parts by weight), the desired improvement in kneading processability cannot be expected. That is, by using a polymer with a high vinyl acetate content, the polymer tends to adhere to metal, and the kneading processability becomes significantly worse. Therefore, as a result of various studies, it was found that adding this calcium-based compound is extremely effective.

As described above, the flame-retardant electrical insulating composition of the present invention made of these materials is crosslinked by peroxide, electron beam irradiation, etc. in order to obtain various desired physical properties.

[0013]

[Function] As described above, the present invention provides an ethylene vinyl acetate copolymer having a vinyl acetate content of 20% by weight or more or a polymer blended so that the vinyl acetate content is 20% by weight or more. In contrast, metal hydroxide surface-treated with vinylsilane or aminosilane was
By mixing 0 to 300 parts by weight, it is possible to achieve the desired flame retardancy, and by surface treating the metal oxide with vinylsilane or aminosilane, the affinity of the metal hydroxide can be greatly improved. , wear resistance and oil resistance are improved. In addition, by adding at least 0.5 parts by weight of a calcium-based compound Ca(OOCR)n (R is an alkyl group, n is a natural number) together with this metal hydroxide, kneading processability is improved and the desired flexibility is achieved. It becomes possible to have the same gender.

[0014]

[Embodiment] An embodiment of the present invention will be described below.

[0015]

[Table 1]

Table 1 shows various examples 1 of formulations according to the invention.
6 shows various evaluations of various compositions of Comparative Examples 1 to 4 of Comparative Examples 1 to 6 and other formulations. Various methods for evaluating various compositions include preparing predetermined amounts of each component by kneading them in a Banbury mixer, and then evaluating tensile properties, oil resistance, abrasion resistance, flame retardance, and kneading processability. The various evaluation methods are as follows.

■ Tensile properties After kneading, a sheet with a thickness of 1 mm was rolled out using a 6-inch roll, and
Crosslinking was carried out at 80°C for 10 minutes. Thereafter, a tensile test was conducted on the test piece punched out using a JIS dumbbell No. 4 using a Schopper type tensile tester at a tensile speed of 500 mm/min. For oil resistance, a sample punched out with this JIS dumbbell No. 4 was used, and after immersing it in ASTM #2 oil at 100°C for 24 hours,
After 24 hours had passed, a tensile test was conducted and evaluated.

■Abrasion resistance In accordance with JISO-D-611, a 0.75φ needle was placed on a 2 mm thick sheet, a load of 800 g was applied, and the abrasion thickness was examined. One reciprocation of the needle was counted as one test, and after 500 tests, if the abrasion thickness was 1 mm or less, it was passed, and if it exceeded 1 mm, it was judged to be rejected.

■ After kneading with a flame-retardant Banbury mixer, the temperature is 100 to 130°C.
80mm extruder held at (screw L/D=
20), a 0.2 mm thick copper tape was wrapped around a wire core made by twisting three ethylene propylene rubber insulated wires with an outer diameter of 4.0 mm, and then extrusion coating was applied to a thickness of 2 mm, and a pressure of 13 cm/ A cable was produced by crosslinking in cm2 of water vapor for 3 minutes.

[0020] Then, 10 cables with a length of 2.4 m were lined up vertically, and 2 flames of 70,000 BTU/hr were placed at the bottom end.
After applying the flame for 0 minutes, remove the flame and pass if the flame self-extinguishes within 1.8 m. If the flame spreads over 1.8 m, the test is failed. (This test is a vertical tray combustion test in accordance with IEEE Standard 383.) .

(2) Kneading processability After thorough kneading at 100° C., those that did not stick to the rotor and could be easily taken out were rated as good kneading properties, and those that significantly stuck to the rotor were rated as poor.

As is clear from Table 1, Examples 1 to 6
Each of the compositions exhibited a tensile strength exceeding 0.9 mm/mm, and the tensile properties maintained 70% or more of the initial value even after the oil resistance test. In addition, both have good wear resistance, flame retardancy, and kneading processability.

On the other hand, Comparative Example 1 in which the flame retardant was mixed in an amount of 30 parts by weight, which is less than the limit value of the present invention, failed in abrasion resistance and flame retardancy. Moreover, in Comparative Example 2, in which the vinyl acetate content was 12% by weight (*3), which is less than the limiting value of the present invention, the oil resistance was significantly lowered compared to Examples 1 to 6. In addition, flame retardants surface-treated with stearic acid (*6)
In Comparative Example 3 using , the abrasion resistance was rejected. Also,
Comparative Example 4, in which a lubricant other than the calcium-based compound specified in the present invention was added, had very poor kneading processability.

That is, as can be seen from Table 1, the oil resistance of ethylene vinyl acetate copolymers with a vinyl acetate content of less than 20% by weight or polymers with a vinyl acetate content of less than 20% by weight decreases; If the amount of the flame retardant mixed in is less than 50 parts by weight per 100 parts by weight of the polymer, the abrasion resistance and flame retardance will fail. Furthermore, if the flame retardant to be mixed is surface-treated with stearic acid, the wear resistance will be rejected, and if a lubricant other than a calcium-based compound is added, the kneading processability will be significantly deteriorated.

Therefore, the flame retardant electrical insulation composition of the present invention uses an ethylene vinyl acetate copolymer having a vinyl acetate content of 20% by weight or more, or a polymer blended so that the vinyl acetate content is 20% by weight or more. This prevents a decrease in flexibility and oil resistance. In addition, by mixing 50 to 300 parts by weight of a metal hydroxide surface-treated with vinylsilane or aminosilane to 100 parts by weight of the polymer, it is possible to provide the desired flame retardance. In addition, by surface-treating the metal oxide with vinylsilane or aminosilane, the affinity of the metal hydroxide is greatly improved, and the wear resistance and oil resistance are improved. In addition, together with this metal hydroxide, a calcium-based compound Ca(OOCR)n (R is an alkyl group, n is a natural number)
By adding at least 0.5 parts by weight or more, it is possible to improve kneading processability and provide desired flexibility.

[0026]

[Effects of the Invention] In summary, according to the present invention, it is possible to have the abrasion resistance, oil resistance, flexibility, etc. required for insulators such as electric wires and cables, as well as excellent flame retardancy. This has the excellent effect of greatly improving the durability and reliability of insulating materials such as electric wires and cables.

Claims (1)

[Claims] Claim 1: In an ethylene vinyl acetate copolymer having a vinyl acetate content of 20% by weight or more or a polymer blended so that the vinyl acetate content is 20% by weight or more, vinylsilane or 50 to 300 parts by weight of metal hydroxide surface-treated with aminosilane is mixed, and calcium-based compound Ca (OOCR)
n (R is an alkyl group, n is a natural number) at least 0.
A flame-retardant electrical insulating composition, characterized in that it contains 5 parts by weight or more.