JPS6076549A - Flame retardant resin 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 [Background and Objects of the Invention] The present invention relates to a flame-retardant resin composition that is flame-retardant and foams and carbonizes when exposed to flame to form a heat insulating layer.

For example, in electric wires and cables, polyethylene, 413 polyethylene, ethylene-propylene copolymer rubber, etc. are used as insulators.

These insulators are flammable, and in order to impart flame retardancy, it has been attempted to incorporate flame retardants such as halogen compounds into the insulators.

Addition of a flame retardant to a thermoplastic resin involves sacrificing the excellent electrical, mechanical, and chemical properties of the resin molded product, and is also unfavorable from the viewpoint of processability and economy.

For this reason, it is being considered to strengthen the flame retardancy of the protective sheath by adding no or only a small amount of flame retardant to the insulator.

The properties required of such a protective sheath include not only flame retardancy, but also resistance to softening or melting due to the heat of a fire, and excellent heat insulation properties. It can be said that it is best to form a strong foamed carbonized layer by heat.

Various resin compositions have been proposed that form a foamed carbonized layer when exposed to heat during a fire, but a resin compound that forms a foamed carbonized layer that can sufficiently protect the interior has not yet been obtained. .

The present invention is based on the above, and aims to provide a flame-retardant resin composition that has flame retardancy and can form a strong foamed carbonized layer when exposed to flame.

[Summary of the invention] The formation of a foamed carbonized layer is particularly important in electric wires and cables that are mainly composed of combustible materials.The formation of the foamed layer blocks heat, softens the internal combustible resin due to a rise in temperature, and Prevents liquefaction, gasification, etc. This foamed carbonized I- must not develop cracks, cracks, etc. when exposed to flame.
Also, it cannot be lost due to falling. In order for the foamed carbonized layer to maintain its shape even after long-term contact with flame, it is important that it quickly turn into a carbide.

Thus, the present invention comprises (a) a resin component containing polyvinyl chloride, an ethylene-vinyl acetate copolymer, and chlorinated polyethylene, (b) a zinc compound, (C) a compound of acrylic acid and/or methacrylic acid, ( d) A flame-retardant resin composition comprising one or more selected from oxides, hydroxides, and carbonates of antimony, molybdenum, silicon, aluminum, magnesium, and calcium.

In the present invention, polyvinyl chloride includes homopolymers, copolymers mainly composed of vinyl chloride,
For example, vinyl chloride and ethylene-vinyl acetate, ethylene-
A graft copolymer of ethyl acrylate, chlorinated polyethylene, polyurethane, etc., or a copolymer of vinyl chloride, ethylene, propylene, vinyl acetate, etc. may be used.

The ethylene-vinyl acetate copolymer has a vinyl acetate content of 15 ffim% or more and a melt index of 1.
Particularly preferred are those of 5 or less. Of course, this also includes those based on ethylene-vinyl acetate, such as Levaloy, a trade name commercially available from Dllpont.

As the chlorinated polyethylene, one having a salt content of 35 to 45% is particularly preferable.

Any combination of polyvinyl chloride, ethylene-vinyl acetate copolymer and chlorinated polyethylene may be used, but for example, for 100ffi star part of polyvinyl chloride, ethylene-vinyl acetate copolymer
A total of 3 vinyl acetate copolymer and chlorinated polyethylene
It is preferably 0 mass part or more.

Moreover, it is preferable that 10 mm or more of each of the ethylene-vinyl acetate copolymer and the chlorinated polyethylene is contained.

The combination of these three types of polymers is achieved through a delicate balance of the polymer's carbonization, melt viscosity, gasification, and foamability during flame contact, as well as its retention properties. This is an essential combination for formation.

Zinc compounds are good dehydrochlorination agents for polyvinyl chloride,
In other words, it is a zinc compound that has a carbonization catalytic effect, and the released hydrogen chloride works effectively to impart flammability and as a foaming gas, and at the same time carbonizes polyvinyl chloride and chlorinated polyethylene after dehydrochlorination. As for lead carbonate,
Examples include zinc borate, zinc phosphorus, zinc pyromellitate, etc., and the content is 100ffif of polyvinyl chloride.
It is appropriate to use 0.5 gLm part or more for the fi part.

The compound of acrylic acid and/or methacrylic acid is, for example, methyl methacrylate, and is specifically known under the trade names Metablane P, Metablane L, etc. commercially available from Mitsubishi Rayon Co., Ltd.

These metabranes are widely recognized as processing aids and high molecular weight lubricants for polyvinyl chloride, but the inventors have recognized that these compounds exhibit extremely unique behavior in forming a foamed carbonized layer when exposed to flame. Ta.

That is, it was found that there was a significant difference in the formation of foamed cells in the foamed carbonized layer formation stage at 200° C. or higher between when these compounds were added and when these compounds were not added.

The amount of acrylic acid and/or methacrylic acid added is not particularly limited, but is 0 to 100 parts under pressure of polyvinyl chloride.
．． A range of 5 to 20 parts by weight is particularly effective.

Antimony, molybdenum, silicon, aluminum, magnesium, calcium oxides, hydroxides or jA
As acid salts, antimony dioxide, molybdenum dioxide,
Examples include silicon dioxide, aluminum hydroxide, alumina oxide, magnesium hydroxide, magnesium carbonate, calcium carbonate, etc., and these may be used alone or in combination of two or more.

Naturally, materials such as clay and talc, which are composed of aggregations of oxides such as aluminum oxide, silicon oxide, and magnesium oxide, are also included in the range.

These are inorganic compounds, and during combustion, most of them remain in the carbide with almost no change, and are separated from the carbide from the polymer to form a strong residual film after combustion.

The amount of the above-mentioned compound added is not particularly limited, and the more the better, but in consideration of other physical properties, the preferred range is 5 to 150 parts by weight per 100 parts by weight of polyvinyl chloride.

In the present invention, in addition to the various components mentioned above, plasticizers, stabilizers, lubricants, flame retardants, fillers, antioxidants, colorants, etc. may be added. Furthermore, it is also possible to add a polyfunctional monomer and apply a free radical generator or an energetic beam to create a three-dimensional cross-linked structure to improve heat deformation resistance and the like.

The composition of the present invention is particularly effective as a protective material for flammable insulators or sheaths of electric wires and cables, but can also be used as a protection material for other combustible products. When this ready-made material is used as a protective material, it may be directly molded onto the outer periphery of a combustible product by extrusion or the like, or it may be formed into a tape, tube, etc. and then applied to the flammable product.

[Examples and Comparative Examples] Compositions were prepared using the blending ratios shown in the 6 examples in Table 1.

Next, a copper wire having a diameter of 5 m+n was coated with polyethylene as an insulator to a thickness of 1.2 mm (G), and the above composition was coated on the outer periphery by extrusion to a thickness of 1 mm to obtain an electric wire.

The evaluation results for the obtained electric wires are as shown in the lower column of Table 1.

The combustion test was conducted by placing the electric wire directly on the ground and setting the inner flame height to 50III.
11. Bunsen burner flame with external flame height 100o+m 4
Three cycles were performed at an angle of 51 gL with one cycle of 30 seconds of flame contact and 30 seconds of flame removal, and those that did not extinguish for 30 seconds or more in any cycle were rejected.

Regarding the cracked state of the sheath, the sheath was open and the insulator was exposed, and depending on the size, it was classified as a crack (opening of 1 mm or less) or crack (opening of 2 mm or more).

The thickness of the foamed carbonized layer was measured after 3 cycles of flame application and flame removal.

The state of the insulator was observed after three cycles of flame application and flame removal.

Table 1 (mixed genus unit is m@part)

Claims (1)

[Claims] (+) (a) a resin component containing polyvinyl chloride, an ethylene-vinyl acetate copolymer, and chlorinated polyethylene, (b) a zinc compound, (C) an acrylic acid and/or methacrylic acid A flame-retardant resin composition comprising: a compound; (d) one or more selected from oxides, hydroxides, or carbonates of antimony, molybdenum, silicon, aluminum, magnesium, and calcium; .