JP3165490B2 - Flame retardant electrical insulation 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 flame-retardant composition which does not generate harmful halogen-based gas during combustion, and which has excellent extrusion characteristics and is particularly suitable as an insulating material and sheath material for electric wires and cables. The present invention relates to an electrical insulating composition.

[0002]

2. Description of the Related Art Olefin polymers have been widely used as insulating layers and sheath layers of insulated wires because of their excellent electrical properties, low cost and good workability. However, since olefin-based polymers are flammable substances themselves, when applied to the above-mentioned applications, it is necessary to impart high flame retardancy from the viewpoint of safety and fire prevention. A method of incorporating a halogen-based flame retardant or the like into a polymer has been widely adopted. However, these generate a large amount of halogen-based gas during combustion, causing problems such as corrosiveness to surrounding equipment and toxicity to the human body. A method of mixing an inorganic hydrate such as aluminum hydroxide or magnesium hydroxide has been proposed.

[0003]

However, the above-mentioned method can impart high flame retardancy by mixing a large amount of an inorganic hydrate with an olefin polymer, but on the other hand, the olefin polymer cannot be used. This causes a new problem that the excellent original workability and mechanical properties are significantly reduced.

[0004] The present invention has been made based on these points, and its object is to impart high flame retardancy without impairing the processability and mechanical properties of olefin-based polymers, and to provide harmful substances. An object of the present invention is to provide an electrical insulating composition which does not generate any halogen-based gas.

[0005]

In order to achieve the above object, the flame-retardant electrical insulating composition according to the present invention comprises 100 to 300 parts by weight of an inorganic hydrate with respect to 100 parts by weight of an olefin-based polymer; , Lithium carbonate, lithium borate
And 0.5 parts by weight or more of a lithium compound selected from lithium, lithium phosphate and lithium fluoride .

The olefin polymer used in the present invention includes polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-α-olefin copolymer , An ethylene-propylene copolymer, and the like, which are used alone or in combination of two or more. Further, these may be used as main components, and a crosslinkable component may be appropriately contained together with these.

Examples of the inorganic hydrate include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, hydrotalcite and the like. These are mixed with 100 to 300 parts by weight based on 100 parts by weight of the olefin polymer. Preferably. If the amount is less than 100 parts by weight, the desired high flame retardancy cannot be obtained. If the amount exceeds 300 parts by weight, the viscosity of the composition increases and the processability such as extrusion is remarkably reduced, and the decrease in mechanical strength is large. Not practical.

In the present invention, flame retardancy can be greatly improved by adding a lithium compound in addition to the inorganic hydrate. As lithium compounds,
Examples thereof include lithium carbonate, lithium borate, lithium phosphate, and lithium fluoride, and particularly preferably, lithium carbonate is used. The lithium compound is preferably added in an amount of 0.5 part by weight or more based on 100 parts by weight of the olefin-based polymer. If the amount is less than 0.5 part by weight, a significant improvement in flame retardancy cannot be obtained. Can not solve.

In the present invention, in addition to the above components, a filler,
A reinforcing agent, a processing aid, a cross-linking agent, a cross-linking auxiliary, an antioxidant, a coloring agent, a flame retardant auxiliary, and the like may be appropriately added.

[0010]

According to the present invention, a high degree of flame retardancy can be realized without mixing a large amount of inorganic hydrate, thereby impairing the excellent processability and mechanical properties inherently possessed by olefin polymers. Nothing.

[0011]

The present invention will be described in more detail with reference to the following examples. The materials used in the examples and comparative examples are shown in Table 1.
It was shown to.

[0012]

[Table 1]

As a working method, the materials shown in Table 2
The composition thus obtained was kneaded with an inch open roll, and the composition thus obtained was heated and crosslinked with a press at a crosslinking temperature of 180 ° C. for a crosslinking time of 10 minutes to obtain a sheet having a thickness of about 1.0 mm. Using these sheets, JIS C 3005, J
Each evaluation was performed based on IS K7201 and the results are shown in Table 2. The oxygen index was evaluated using a flammability tester ON-1 manufactured by Suga Test Instruments Co., Ltd. In addition, extrusion processability,
Using a 20 mmφ resin extruder with a L / D = 20 and a compression ratio of 2.0, a tube having a thickness of 0.5 mm and an inner diameter of 4 mm was extruded under the conditions of a set temperature cylinder of 100 ° C. and a head of 120 ° C., and evaluated. It was also described in. In this example, lithium carbonate was used as the lithium compound.

[0014]

[Table 2]

As can be seen from Table 2, the compositions according to the present invention (Examples 1 to 7 ) all have a tensile strength of 6.8 MPa or more, an elongation of 230% or more, and oxygen The index is 34 or more, indicating that the flame retardancy is also very good. Also, the extrudability is good. On the other hand, Comparative Example 1 is a case where the amount of the inorganic hydrate to be mixed is less than the range of the present invention, but the lithium compound (lithium carbonate)
Has an effect of improving the flame retardancy, the oxygen index is as low as 27, which is not high. Conversely, when the amount of the inorganic hydrate exceeds the range of the present invention as in Comparative Example 4, the tensile strength and elongation are significantly reduced, and furthermore, extrusion is difficult. Also, Comparative Example 2 is a case of not adding a lithium compound (lithium carbonate), although Comparative Example 3 is a case where the addition amount of lithium compound (lithium carbonate) is less than the scope of the present invention, Example 3 and As can be seen from comparison with Example 4 , since the effect of improving the flame retardancy of the lithium compound (lithium carbonate) cannot be obtained, the oxygen index is as low as 29 and the flame retardancy is insufficient, which is not preferable.

[0016]

As described in detail above, according to the present invention,
In a flame-retardant olefin-based polymer composition that does not generate harmful halogen-based gas during combustion, lithium carbonate,
From lithium oxalate, lithium phosphate or lithium fluoride
By adding a specific amount of the selected lithium compound,
A high degree of flame retardancy can be realized without impairing the excellent processability and mechanical properties of the olefin polymer. For this reason, this flame-retardant electrical insulating composition is particularly suitable as a covering material such as an insulating material or a sheath material for electric wires and cables, and a highly safe molded product that does not generate harmful gas during combustion can be obtained. It is informative.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 23/00-23/36 C08K 3/00-13/08 H01B 3/44

Claims (2)

(57) [Claims] 1. An inorganic hydrate of 100 to 300 parts by weight per 100 parts by weight of an olefin-based polymer, and lithium carbonate, lithium borate, lithium phosphate or lithium phosphate.
Is a flame-retardant electrical insulating composition containing 0.5 parts by weight or more of a lithium compound selected from lithium fluoride . 2. The flame-retardant electrical insulating composition according to claim 1, wherein the lithium compound is lithium carbonate.