JPS6072946A - Fire-retardant resin composition - Google Patents

Abstract

PURPOSE:The titled composition, which has fire retardancy and forms a strong foamed carbonized layer when brought into contact with flame, comprising a resin component made of PVC and a specified copolymer, a zinc compound, and a (meth)acrylic acid compound. CONSTITUTION:The fire-retardant resin composition comprises a resin component (A) containing PVC and an ethylene-vinyl acetate copolymer, a zinc compound (B) (e.g. zinc carbonate), and a compound of acrylic and/or methacrylic acid (C). The resin component (A) composed of two types of polymers serves to form a heat-insulating foamed carbonized layer, while the compound (B) acts as a carbonization catalyst. The compound (C) also serves to form a foamed carbonized layer when brought into contact with flame. The above combination can give the composition fire retardancy, and enables it to foam and be carbonized to form a heat-insulating layer when brought into contact with flame.

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, crosslinked polyethylene, ethylene-propylene 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.

Adding a twisting agent to a thermoplastic resin entails sacrificing the excellent electrical, mechanical, and chemical properties of the resin molded article, 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 additional twist agent 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. The best method is to form a strong foamed carbonized layer by applying heat.

Various resin compositions have been proposed that form a foamed carbonized layer due to heat generated during a fire, but a resin composition that can form 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 JfJ when exposed to flame.

[Summary of the Invention The formation of a tm carbonized layer is especially possible with combustible materials! It is important in electric wires 9 cables having a structure mainly composed of 4, and the formation of the ttt layer blocks heat and prevents the internal combustible resin from softening, liquefying, gasifying, etc. due to temperature rise. This foamed carbonized layer must not develop any cracks, cracks, cracks, etc. when exposed to flame, and may fall off due to falling.0 The foamed carbonized layer maintains its shape even when in contact with flame for a long time. In order to achieve this, it is important to quickly turn into carbide.

Thus, the present invention provides a flame retardant material comprising: (a) a resin component containing polyvinyl chloride and an ethylene-vinyl acetate copolymer, (b) a zinc compound, and (C) a compound of acrylic acid and/or methacrylic acid. A resin composition is provided.

Polyvinyl chloride according to the present invention includes homopolymers, copolymers mainly composed of vinyl chloride,
For example, vinyl chloride and ethylene-vinyl acetate, ethylene-
It may be a graft copolymer with ethyl acrylate, chlorinated polyethylene, polyurethane, etc., or a copolymer of vinyl chloride with ethylene, propylene, vinyl acetate, etc.

The ethylene-vinyl acetate copolymer has a vinyl acetate content of 15fE% or more and a melt index of 15.
The following are particularly preferred, and of course also include those based on ethylene-vinyl acetate, such as Luvaloy, a trade name commercially available from Dupo++.

The ethylene-vinyl acetate copolymer is softened by the temperature rise during flame contact, and the decomposed gas generated at the same time helps foaming, and is preferably 30 parts by weight or more per 100 ffi parts of vinyl chloride.

The combination Uo of these two types of polymers is achieved based on a delicate balance of carbonization, melt viscosity, gasification, foamability, and other properties of the polymers when exposed to flame, and is effective in forming a foamed carbonized heat insulating layer.・It is an essential silk combination.

Zinc compounds are good dehydrochlorination agents for polyvinyl chloride,
In other words, it has a carbonization catalytic effect, and the released hydrogen chloride acts effectively as a flame-retardant agent and foaming gas, and at the same time, it is effective in forming polyvinyl chloride and chlorinated polyethylene after dehydrochlorination. Carbonize.

Zinc compounds include zinc carbonate, zinc borate, zinc phosphate, and pyromellit i! ! Examples include zinc, and the content thereof is 0.5ii per 100ffi parts of polyvinyl chloride.
11 copies or more is appropriate.

The compound of acrylic acid and/or methacrylic acid is, for example, methyl methacrylate, and specifically, it is known under the trade names of Metablane P1 and Metablane L, which are 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 present inventors have discovered that these compounds exhibit extremely unique behavior in forming a foamed carbonized layer when exposed to flame. Admitted.

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 per 100 melon parts of polyvinyl chloride.
．． A range of 5 to 20 dish melon parts is particularly effective.

In the present invention, in addition to the above-mentioned various components, plasticizers, stabilizers, lubricants, flame retardants, fillers, antioxidants, color enhancers, etc. may be added, and polyfunctional monomers may also be added, and free radical generators may be added. It is also possible to achieve three-dimensional cross-linking by applying or energetic wires to improve heat deformation resistance, etc.

The compositions of the present invention are particularly effective as protectants for flammable insulation or sheaths of electric wires and cables, but may also be used as protectants for other combustible products. When this composition is used as a protective material, it may be molded directly onto the outer periphery of a flammable product by extrusion or the like, or it may be molded 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 Table 1.

Next, a copper wire having a diameter of 5 mm was coated with cross-linked polyethylene as an insulator to a thickness of 1.2+n, and the above composition was extrusion coated on the outer periphery to a thickness of 1+u+ to obtain an electric wire.

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

In the combustion test, the electric wire was placed vertically, and the height of the inner flame was 50mm,
A Bunsen burner flame with an outer flame height of 100 mm was used at an angle of 45 degrees for 6 cycles, each cycle consisting of 15 seconds of flame application and 15 seconds of flame removal, and those that did not extinguish for 60 seconds or more in any cycle were rejected.

In addition, the occurrence of cracking and foaming carbonization were observed, and the thickness of the foaming carbonization layer was measured.

[Effects of the Invention] As is clear from the above explanation, the flame-retardant resin footwear of the present invention can foam and carbonize when exposed to flames to form a strong cracked layer, and has extremely excellent combustibility. It exerts a protective effect on the protective material.

Claims (1)

[Claims] (+) (F) a resin component containing polyvinyl chloride and an ethylene-vinyl acetate copolymer, (b)! I! ! A flame-retardant resin composition comprising: a lead compound; (C) a compound of acrylic acid and/or methacrylic acid.