JPS60161444A - Low smoke softening composition - Google Patents

Abstract

PURPOSE:A composition, obtained by incorporating ethylene-vinyl acetate copolymer resin and ethylene-propylene rubber with a hydrated inorganic compound, red phosphorus and a silane coupling agent, and crosslinking the resultant mixture, having high flame retardancy, low-smoking properties and improved flexibility and electrical characteristics. CONSTITUTION:A low-smoking flexible composition obtained by incorporating (A) 80-20pts.wt. ethylene-vinyl acetate copolymer resin with 5-30wt% vinyl acetate content and (B) 20-80pts.wt. ethylene-propylene rubber with 50-200pts. wt. hydrated inorganic compound, preferably aluminum hydroxide, (D) 5-50pts. wt. red phosphorus, preferably fine particulate red phosphorus having the surface coated with a resin and (E) 0.5-5pts.wt. silane coupling agent, preferably having vinyl group, and crosslinking the resultant mixture by irradiation with electron rays. The content ratio between the components (C) and (D) is preferably 1:5 to give particularly high flame retardancy.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention provides a flame-retardant resin composition that emits significantly less smoke when burned, and is suitable for use in electric wires for vehicles, etc., which require particularly excellent flexibility and electrical properties. The present invention relates to a composition used for an insulator.

[Background of the invention]

Flame retardation of conventional polyolefin resins is often achieved by the combined use of halogen-containing flame retardants and antimony trioxide. However, although such a composition exhibits a high degree of flame retardancy because it contains halogen, it generates a large amount of smoke when burned, which is a problem.

It is known to add a large amount of a hydrated inorganic compound such as aluminum hydroxide to a polyolefin resin as a composition that generates less smoke during combustion. Regarding smoke generation, this composition produces less smoke than a composition that uses a combination of the above-mentioned halogen-containing flame retardant and antimony dioxide, but it still cannot be put into practical use because it does not have satisfactory low smoke generation and flame retardancy. Not yet.

In particular, it has been difficult to provide a composition that has both excellent flexibility and electrical properties when a large amount of hydrated inorganic compound is added.

[Summary of the invention]

The present invention was made in view of the above points, and contains 80 to 20 parts by weight of an ethylene vinyl acetate copolymer resin having a vinyl acetate content of 5 to 1 wt%, and 20 to 80 parts by weight of ethylene propylene rubber. Water use inorganic compounds 50-200
The present invention provides a crosslinking composition containing 5 to 50 parts by weight of red phosphorus and 0.5 to 5 parts by weight of a silane coupling agent.

The composition of the present invention has sufficiently high flame retardancy and low smoke emission, and is also excellent in mechanical properties including flexibility and electrical properties.

[Detailed description of the invention]

In the present invention, the amount of vinyl acetate is 5wt96 to 50wt4
When a mixture of ethylene vinyl acetate copolymer resin and ethylene propylene rubber (including ethylene propylene diene terpolymer) is used, a composition with good flexibility can be obtained. The mixing ratio of ethylene vinyl acetate copolymer resin and ethylene propylene rubber is 80 to 20 parts by weight of ethylene vinyl acetate copolymer resin and 20 to 20 parts by weight of ethylene propylene rubber.
Parts by weight: 80 ethylene vinyl acetate copolymer resin
If the amount of ethylene propylene rubber is less than 20 parts by weight, the flexibility will not be sufficient, and if the amount of ethylene-vinyl acetate copolymer resin is less than 20 parts by weight and the amount of ethylene propylene rubber exceeds 80 parts by weight, the tensile strength at break will be is no longer sufficient. Further, the ethylene vinyl acetate copolymer resin used has a vinyl acetate content of 5 wt% to 30 wt96. 5wt
If it is less than 4, the flexibility will not be sufficient, and if it exceeds 80 wt%, the tensile strength at break will not be sufficient.

Examples of water conserving inorganic compounds include aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium hydroxide, barium hydroxide, etc., and aluminum hydroxide is particularly preferred because it provides higher flame retardancy.

Red phosphorus exists as elemental phosphorus when it is contained in resin, and when kneading it into resin, it is mixed into the resin to prevent oxidation ring reactions from occurring on the surface of the red phosphorus particles, due to the hygroscopicity of the generated phosphoric acid. In order to prevent moisture from adhering to the surface and to prevent ignition due to increased temperature, it is preferable to knead particles of red phosphorus whose surfaces are coated with a resin. It is also possible to incorporate red phosphorus into the resin by mixing it with the resin.

The reason why a hydrated inorganic compound and red phosphorus are used together in the present invention is to obtain a highly flame-retardant and low-smoking composition.Although the water-containing inorganic compound alone exhibits low smoke-emitting properties, the flame retardance is satisfactory. It is not something that should be done, and even red phosphorus alone is not satisfactory in terms of flame retardancy.

The contents of water conserving inorganic compounds and red phosphorus per 100 parts by weight of the resin components (ethylene vinyl acetate copolymer and ethylene propylene rubber) are 50 to 200 parts by weight and 5 to 5 parts by weight, respectively.
50 parts by weight, the water use inorganic compound exceeds 200 parts by weight,
In addition, if the amount of red phosphorus exceeds 50 parts by weight, the mechanical properties of the composition will deteriorate so much that it cannot be used.
When the amount is less than 5 parts by weight, sufficient flame retardancy cannot be obtained.

In particular, when the content ratio of the water-use inorganic compound and red phosphorus is 5 parts inorganic compound to 1 part red phosphorus, high flame retardance can be obtained, which is preferable.

Furthermore, in the present invention, a silane coupling agent is added in order to obtain excellent electrical properties; if the silane coupling agent is not added, electrical properties such as insulation resistance will not be sufficient. Further, the content of the silane coupling agent is preferably 0.5 to 5 parts by weight, and if it is less than 0.5 parts by weight, the electrical properties will not be sufficient, and if it exceeds 5 parts by weight, flame retardancy will deteriorate and plume will occur, which is not preferable.

Further, crosslinking may be carried out by chemical crosslinking using an organic peroxide or crosslinking by electron beam irradiation (electron beam irradiation), and electron beam crosslinking is preferable because it generates less smoke.

In addition to the hydrated inorganic compound, red phosphorus, the composition of the invention includes:
Anti-aging agents, colorants, processing aids, crosslinking aids, softeners, ultraviolet deterioration inhibitors, etc. may be added as appropriate.

〔Example〕

The various formulations shown in Table 1 were mixed using a Banbury mixer, burned, and then 1 ram and 2 mm thick sheets were produced using a hot press.

The following various tests were conducted on the obtained breath sea) K. The results are also shown in Table 1.

(1) Flame retardancy The oxygen index of the 2 mm receipt was measured according to JIS K7201 to evaluate the flame retardance.

(11) Tensile strength, elongation, and 100% modulus The tensile strength and elongation of the 1M thick sheet were measured according to JIS C800516.

At that time, the force at 100% elongation (100% modulus) was also calculated.

(iii) Smoke generation The amount of smoke generated was measured for the 1 mJl sheet using an NBS smoke chamber. The maximum amount of smoke was determined by conducting two tests, one without flame and one with flame. The maximum amount of smoke generated is calculated using the following formula, and the smaller the value, the less amount of smoke generated.

Here, V: NBS smoke chamber capacity (18f
t3), A: Surface area of the sample (6,25 inches) L: Optical path length (lft), T: Minimum light transmittance (96) Gy
) Insulation Resistance The thick sheet was forced to absorb water at 120° C. for one day, and then the volume resistivity was measured using a super megohmmeter.

(Note 1) Manufactured by Sumitomo Chemical Co., Ltd. However, in Comparative Example 5, polyethylene was used.

(Note 2) Manufactured by Sumitomo Chemical (Note 3) Manufactured by Sanken Kako ■Product name: Sumperosox DCP (
Note 4) Shin-Etsu Chemical ■ (Note 5) Manufactured by Showa Light Metal ■, product name Hisilite H32
(Note 6) Manufactured by Phosphorus Handicraft ■, product name Nobalet +12
0 (Note 7) In Example 2, the irradiation dose for electron beam crosslinking was 24 Mrad.As can be seen from the results in Table 1, the compositions of the present invention (Examples 1 to 8) had a high % modulus value), electrical properties, flame retardancy (high oxygen index), and low smoke generation, but the composition that does not contain a silane coupling agent (Comparative Example 1) has an insulation resistance of i, oxio Composition with low Ω,an and 10 parts by weight of ethylene propylene rubber (Comparative Example 2)
has low elongation and therefore insufficient flexibility, and the composition containing 90 parts by weight (Comparative Example 8) has low tensile strength. The composition containing a halogen-containing flame retardant (Comparative Example 4) produced a significantly large amount of smoke. In addition, a composition in which vinyl acetate in the ethylene vinyl acetate copolymer was 40% by weight (Comparative Example 6) had a tensile strength at break of 0.80 kg/+am'', which was not sufficient.
The six-set acid compound (Comparative Example 5) using polyethylene that does not contain vinyl acetate has an elongation of 48,096 and insufficient flexibility.

From the above results, the effects of the present invention are clear.

Agent Patent attorney Tetsu Tsukasa Udai (♂, □1 trouble 5.)'

Claims (1)

Scope of Claims: (1) 50 to 200 parts by weight of a hydrated inorganic compound is added to 80 to 20 parts by weight of an ethylene vinyl acetate copolymer resin having a vinyl acetate content of 5 to 80 wt4 and 20 to 80 parts by weight of ethylene propylene rubber. parts, 5 to 50 parts by weight of red phosphorus,
A low-smoke flexible composition containing 0.5 to 5 parts by weight of a silane coupling agent and characterized by crosslinking (2) A composition using particulate red phosphorus whose surface is coated with a resin as the red phosphorus. (3) The low-smoke flexible composition according to item 1, characterized in that the water-use inorganic compound is aluminum hydroxide (4) Molecular structure (5) The low-smoke flexible composition according to item 1, characterized in that a silane coupling agent having a vinyl group is used therein;
Low-smoke softening composition described in section