JPH02142006A - Flame retardant electrical insulation composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flame-retardant electrical composition with low smoke emission, low toxicity, and no corrosion, which is suitable as an insulator or sheath material for electrical cables. It is something.

[Prior art] In place of the conventional method of mixing halogen compounds or phosphorous compounds as a flame retardant treatment method for polymers, inorganic hydroxides such as magnesium hydroxide have recently been used from the perspective of placing importance on safety in the event of a fire. The method of mixing things is attracting attention. These materials have the characteristics of being less smoke-producing and toxic than halogen-based compounds and phosphorus-based materials, and are also non-corrosive.

[Problem to be solved by the invention] However, inorganic hydroxides have inferior flame retardancy compared to the above-mentioned halogen-based and phosphorus-based compounds, so they must be mixed in large amounts in order to obtain the same effect. As a result, there is a problem in that mechanical properties such as tensile properties and trauma resistance are significantly reduced.

The present invention has been made in view of these points, and aims to provide a flame-retardant electrical insulating composition that eliminates the drawbacks of the conventional techniques and has improved mechanical properties.

[Means and effects for solving the problem] This invention has the following features:
The present invention relates to a flame-retardant electrical insulation composition characterized in that 50 to 300 parts by weight of an inorganic hydroxide is mixed with 100 parts by weight of an ethylene ethyl acrylate copolymer modified with an unsaturated organic acid or a derivative thereof.

This makes it possible to significantly improve mechanical properties while maintaining flame retardancy.

[Example] In the present invention, an ethylene ethyl acrylate copolymer modified with an unsaturated organic acid or its derivative refers to an ethylene ethyl acrylate copolymer modified with an unsaturated organic acid or its derivative in the presence of an organic peroxide. is obtained by grafting reaction by heating.

Examples of unsaturated organic acids include maleic acid, fumaric acid, ichconic acid, and citraconic acid, and examples of derivatives thereof include anhydrides and metal salts.

The content of unsaturated organic acid or its derivative is
0.01 to 1% by weight based on 0.00.
This is because if it is less than 0.1% by weight, the desired mechanical properties cannot be improved, and if it is more than 1% by weight, the adhesion to metal becomes large and kneading becomes difficult.

In this invention, the above-mentioned modified ethylene ethyl acrylate copolymer is melt flow)-MFRo.
, 1~10g/10min, ethyl acrylate content 15~
A content of 40% by weight is desirable; outside this range, mechanical properties such as tensile properties are significantly reduced.

Inorganic hydroxides suitable for this invention include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, hydrotalcites, and the like. This inorganic hydroxide needs to be mixed in a range of 50 to 300 parts by weight with respect to the above-mentioned modified ethylene ethyl acrylate copolymer], O0 parts by weight, and if it is less than 50 parts by weight, it will not achieve the desired flame retardancy. Moreover, if it exceeds 300 parts by weight, extrusion processability will be significantly reduced and molding will become difficult.

In this invention, in addition to the above two components, a crosslinking agent, an antioxidant,
A lubricant, softener, coupling agent, etc. may be added.

Hereinafter, specific examples of the present invention will be described together with comparative examples. The modified ethylene ethyl acrylate copolymers shown in Examples 1 to 6 and Comparative Examples 1 to 4 in Table 1 were 210
A 40 m/m extruder (L/D=2
5), maleic anhydride is grafted onto an ethylene ethyl acrylate copolymer in the presence of an initiator dicumyl peroxide.

After panburi kneading various ingredients in the mixing ratios shown in Examples 1 to 6 and Comparative Examples 1 to 4 in Table 1, the mixture was heated at 160°C.
An 80 m/m extruder (L/D=
20), the outer periphery of three twisted ethylene propylene rubber insulated wire cores with an outer diameter of 3 mm was coated by extrusion to a thickness of 2 mm, and various cables were prepared and used as samples.

The evaluation results of the cables obtained on each side are summarized in the lower column of Table 1.

For tensile properties, JIS dumbbell No. 3 test pieces were prepared after press molding to a thickness of 1 mm at a temperature of 190° C., and tensile tests were conducted using a Schopper type testing machine at a speed of 200111 m /min.

The scratch resistance was evaluated using the 41:1 JIS C3003 hardness method. The surface of the cable was rubbed with empi and the hardness of the empi was determined at the point where it turned white.

The flame retardant evaluation is 2.4 in accordance with IEEE standard 383.
Eight m-long cables are lined up vertically, 70 and 0 from the bottom.
00 B T U / l]r for 20 minutes, then remove the flame and pass if the flame self-extinguishes at a distance of less than 1.8 m.
Those whose fire spread over 1.8 m were rejected.

On the other hand, Comparative Example 1 with a small content of inorganic hydroxide failed in flame retardancy, and Comparative Example 2 with a content of more than 300 parts by weight had poor extrudability.

Comparative Example 3, in which the above modification was not performed, had poor scratch resistance, and Comparative Example 4, in which a non-specified polymer was used, failed in terms of flame retardancy.

As is clear from Table 1, Examples 1 to 1 according to this invention J
The composition shown in No. 6 has excellent tensile properties and scratch resistance, and passes the vertical tray burn test.

(The following is a blank space) [Effects of the Invention] According to the present invention, a halogen-free flame-retardant electrical insulating composition having excellent mechanical properties such as tensile properties and trauma resistance can be obtained.

Claims (3)

[Claims] 1. A flame-retardant electrical insulation composition prepared by mixing 50 to 300 parts by weight of an inorganic hydroxide with 100 parts by weight of an ethylene ethyl acrylate copolymer modified with an unsaturated organic acid or a derivative thereof. 2. The content of the unsaturated organic acid or its derivative in the unsaturated organic acid or its derivative in the ethylene ethyl acrylate copolymer modified with the unsaturated organic acid or its derivative is 0.01 to 1% by weight based on the polymer. The flame retardant electrical insulation composition according to claim 1. 3. 2. The ethylene ethyl acrylate copolymer modified with an unsaturated organic acid or its derivative has an MFR (melt flow rate) of 0.1 to 10 g/10 min and an ethyl acrylate content of 5 to 40% by weight. Flame retardant electrical insulation composition.