JPH0649807B2 - Flame-retardant resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a flame retardant excellent in heat aging that can pass a severe flame retardancy test of UL758 VW-1 combustion test by crosslinking by irradiation or by compounding with a chemical crosslinking agent. Resin composition.

In the flame-retardant resin composition of the present invention, a unique combination of resistance to deterioration by heat and flame and excellent electrical properties is essentially important, and low smoke density and non-corrosive vapor are desirable. It is especially useful for insulation of building wires, equipment wires, automobile wires and the like.

In recent years, from the consideration of minimizing damage when a flame of a building is generated, it is required for electric wires and cables to meet extremely strict flame retardancy standards.

One of the most stringent of these standards is the following means as a flame retardant method for the conventional plastic coating material for electric wires and cables to pass the UL758 VW-1 combustion test applied to electric wires and cables. is there.

(i) In the case of vinyl chloride, the flammable plasticizer is reduced and antimony trioxide is added.

(ii) In the case of polyolefin, an organic halogen compound (eg decabromodienyl ether, hexabromobenzene, perchloropentacyclodecane, etc.) and antimony trioxide are added in the order of several tens PHR.

However, since the coating material flame-retarded by such means contains a large amount of halogen, a large amount of harmful halogen gas is generated at the time of combustion, which poses a risk of causing another major disaster at the time of fire.

For this reason, in recent years, many proposals have been made for another means of stopping the addition and use of the halogen-containing compound and mixing the water-containing inorganic compound with the base plastic. However, in order to pass the VW-1 test which is the severe flame retardancy test described above by this method, the amount of the water-containing inorganic compound mixed reaches 2-3 times the amount of the base plastic, which is the other base. It is highly likely that the physical properties of the polymer will be impaired and the properties of the cable covering material will be lost. Japanese Unexamined Patent Publication (Kokai) No. 58-1741 proposes a flame-retardant composition using a specific ethylene-vinyl acetate copolymer, but this composition has a drawback that the tensile elongation at break residual rate decreases after heat aging. Atsuta

In addition, as disclosed in, for example, Japanese Patent Application Laid-Open No. 56-18636, there is known a means capable of significantly improving flame retardancy by filling a remarkably small amount of a water-containing inorganic compound.

However, when the flame-retardant resin composition by such means is extrusion-coated on a cable, the produced insulated electric wires are stacked on top of each other, or wound on a bobbin, and the coated electric wires are stacked and pressed against each other. There has been a drawback that the coating layers adhere to each other and the separability thereof is significantly lowered.

It has been proposed to use a so-called coupling agent in order to modify the surface of an inorganic compound as a means for improving such drawbacks. A coupling agent is a compound that strongly affects the interface between an organic polymer and an inorganic substance or metal and forms a strong bridging between the materials, and two or more different reactive groups are introduced into the molecule. , One of which is chemically bonded to an inorganic substance and the other is chemically bonded to an organic polymer.

Examples of coupling agents include, for example, JP-A-53-110.
No. 644 proposes treatment with a titanate coupling agent. However, although the titanate coupling agent may have an effect of increasing the tensile elongation at break, it generally has a large effect of lowering the rigidity and a strong effect of softening the composition, and is extremely expensive. Further, as shown in JP-A-51-101049, although improvement of impact strength is recognized, the effect of high elongation cannot be expected.

An object of the present invention is to provide a novel halogen-free flame-retardant resin composition which is improved in these drawbacks, does not cause deterioration of properties especially after heat aging, is highly safe and is pollution-free.

The present inventors, as a result of intensive studies to solve the above problems, identified a substrate plastic as described below, and inorganic hydrate surface-treated with a large amount of silane coupling agent (inorganic hydrate The term "indicates a hydrate of a metal oxide and includes metal hydroxide and its hydrate") to solve the above problems by blending amorphous silica and / or carbon black and an epoxy resin. They have found that they can do so and have completed the present invention.

That is, the present invention provides (a-1) a vinyl acetate content of 30% by weight.
The above ethylene-vinyl acetate copolymer, (a-2) a mixture of two or more ethylene-vinyl acetate copolymers having a total vinyl acetate content of 30% by weight or more, or (a-3) these ethylene-acetic acid Vinyl copolymer or ethylene-
100 parts by weight of a mixture having a vinyl acetate content of 30% by weight or more obtained by substituting 20% by weight or less of a vinyl acetate copolymer mixture with polyolefin, and (b) an inorganic hydrate having a surface treated with a silane coupling agent. 250 parts by weight,
(C) 5 to 70 parts by weight of amorphous silica, carbon black or a mixture thereof, and (d) 0.5 to 1 of epoxy resin
Provided is a flame-retardant resin composition containing 0 part by weight.

In the present invention, the reason why the ethylene-vinyl acetate copolymer is specified as described above (in particular, the vinyl acetate content is 30% or more) is that the vinyl acetate content in the base plastic is not more than 30% by weight, preferably 40% by weight or more. This is because it is impossible to pass the VW-1 combustion test while maintaining the excellent mechanical properties and flexibility of the base material plastic. Also, the heat aging resistance is improved in proportion to the increase in vinyl acetate content. Further, in the present invention, the ethylene-vinyl acetate copolymer having a Mooney viscosity of 8 or more is preferable in terms of mechanical properties. Particularly, those of 10 to 60 are preferable.

Polyolefin that is optionally mixed with the ethylene-vinyl acetate copolymer is polyethylene, ethylene-propylene copolymer, ethylene-α-olefin copolymer, or the like. The mixing amount is preferably 20 PHγ or less in order to maintain mechanical properties.

In the present invention, 120 to 250 parts by weight of an inorganic hydrate surface-treated with a silane coupling agent is added to 100 parts by weight of the above-mentioned substrate plastic. If it exceeds the upper limit, the original excellent mechanical properties and flexibility of the substrate plastic will be impaired.

What is particularly important here is to increase the rigidity conventionally known by using an inorganic hydrate surface-treated with 0.1% by weight or more, preferably 1.2% by weight or more of a silane coupling agent. At the same time, it is possible to maintain sufficient tensile elongation at break even after heat aging.

The silane used in the present invention is a silane represented by the general formula RR'SiY2, in which R is a non-hydrolyzable organic group such as an alkyl group or a vinyl group, and Y is a hydrolyzable organic group such as an alkoxy group. , R'is a group R or a group Y
And a vinylalkoxysilane such as vinyltriethoxysilane is particularly preferred. The amount of silane added can vary depending on the amount of inorganic hydrate to be mixed, but it is generally in the range of 0.1 to 5% by weight of the amount of inorganic hydrate. If it is 0.1% by weight or less, the effect of improving heat aging resistance is poor, and if it is 5% by weight or more, the effect is saturated, which is meaningless from an economical point of view, and a tendency for elongation to decrease is also recognized. The theoretical amount of the silane coupling agent necessary for the surface treatment of the inorganic hydrate is 1% by weight, but the range of 1.2 to 3% by weight is particularly preferable from the viewpoint of dispersibility.

As the inorganic hydrate, aluminum hydroxide and magnesium hydroxide are preferable. Magnesium hydroxide is the most preferable in terms of mechanical strength. The treatment of the inorganic hydrate with the silane coupling agent is preferably performed in advance from the viewpoint of dispersibility in the base material plastic.

As the amorphous silica, any commercially available one can be used. An example thereof is Tokushiru (product of Tokuyama Soda Co., Ltd.).

As the carbon black, those that can be mixed with the extrusion-molded resin are preferable, and examples thereof include diamond black FE.
F (product of Mitsubishi Kasei Co.) is mentioned.

Furthermore, a small amount of the base plastic 100 may be added to the composition of the present invention.
Addition of 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, per part by weight of the epoxy resin can improve the heat aging resistance of the composition. Examples of the epoxy resin include a bisphenol type epoxy resin produced by condensation of bisphenol A and epichlorohydrin, a novolak type epoxy resin produced by condensation of novolak resin and epichlorohydrin, an aliphatic cyclic epoxy resin having a cyclohexene oxide structure, and a cyclic acetal structure. Epoxy resin having, a glycol type epoxy resin produced by condensation of polyalkylene ether glycol and epichlorohydrin, and the like, appropriately selected from epoxidized polybutadiene, epoxidized soybean oil, epoxidized linseed oil, etc. according to the purpose of use. be able to. Particularly, a bisphenol type epoxy resin is preferable.

The composition of the present invention can be cross-linked, and as a cross-linking means, known means for plastics, such as radiation cross-linking, peroxide cross-linking, and silane cross-linking can be applied.

Incidentally, the composition of the present invention may be mixed with other additives as necessary, for example, a colorant, a flame retardant, an anti-aging agent, a cross-linking agent, a foaming agent, etc., as long as the characteristics thereof are not deteriorated. it can. An ordinary extruder, Banbury mixer, open roll, or the like is appropriately used for mixing these.

The flame-retardant resin composition of the present invention has high safety, is non-polluting because it does not contain halogen, and has no deterioration in physical properties after heat aging, and is useful for wire coating, wall materials, etc. is there.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples.

Examples 1 to 5 and Comparative Examples 1 to 7 By coating the composition shown in Table 1 on a conductor of 0.5φ and irradiating it with an electron beam of 10 Mrad to crosslink,
A 0.9φ coated electric wire was obtained.

Next, the tests shown in Table 2 were performed on each covered electric wire. The results are listed in the table.

The details of 1) to 17) in Tables 1 and 2 are as follows.

1) Vinyl acetate content = 60%, Mooney viscosity = 55, Dainippon Ink and Chemicals product (Ebaslen 410P) 2) Vinyl acetate content = 60%, Mooney viscosity = 20, Dainippon Ink and Chemicals prototype product 3) Density = 0 .925, MI = 0.5, product of Mitsui Petrochemicals 4) vinyl acetate content = 20%, product of Toyo Soda Co., Ltd. (Ultrasen UE-631) 5) "Hijilite H-42M", without silane coupling treatment, Showa Light Metal Co., Ltd. product 6) 1% by weight vinyltriethoxysilane of "Hidilite H-42" (KBE-1003, product of Shin-Etsu Chemical Co., Ltd.)
7) "Heidilite H-42" with 3% by weight of KBE-1
Surface treated with 003 8) "Kisuma 5A", without silane coupling treatment, Kyowa Chemical Co., Ltd. product 9) "Kisuma 5A" surface treated with 3% by weight of KBE-1003 10) "Tokushiru", Tokuyama Soda Company product 11) Kaolin clay having an average particle size of 5μ 12) Bisphenol type epoxy resin, Dainippon Ink and Chemicals, Inc. product (Epiclon-850) 13) JIS C3005 14) JIS K7216 15) Coated wire wound around a 1 Km bobbin 60 Evaluation is carried out by allowing to stand at 24 ° C. for 24 hours and then rewinding.

16) JIS K7201 17) It is evaluated as passing by passing all 10 test products.

As seen in Tables 1 and 2, Comparative Examples 1, 2, 3, 5, 6
In the case of the compositions of 7 and 7, both have problems in physical properties after heat aging. This is because the vinyl acetate content of the ethylene-vinyl acetate copolymer was less than 30% by weight (Comparative Example 3), and the inorganic hydrate was not treated with the silane coupling agent (Comparative Examples 1, 2 and 5) or the absence of epoxy resin (Comparative Examples 6 and 7). In the case of the composition of Comparative Example 4, clay is used instead of the amorphous silica or the carbon black, and therefore there is a problem in terms of tackiness.

On the other hand, the composition of the present invention is remarkably improved in such problems and the various properties are balanced, so that the composition is an acceptable product as a whole.

As described above, the present invention provides a flame-retardant resin composition in which the conventional problems are eliminated as a result of specifying the composition and the like of the filler using a specific base material plastic, and safety. It has an extremely great effect on the industry, such as improving productivity.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location (C08L 23/02 23:08 31:04 63:00) (C08K 13/06 9:06 3:04 3: 36 3:22) (72) Inventor Shin Kajiwara 6 Yawata Kaigan Dori, Ichihara City, Chiba Furukawa Electric Co., Ltd. Chiba Electric Wire Works (56) References JP-A-58-79040 (JP, A) JP-A-57- 212247 (JP, A) JP-A-61-228049 (JP, A)

Claims (1)

[Claims] 1. An (a-1) ethylene-vinyl acetate copolymer having a vinyl acetate content of 30% by weight or more, and (a-2) two or more kinds of ethylene-acetic acid having a total vinyl acetate content of 30% by weight or more. A mixture of vinyl copolymers or (a-3) 20% by weight or less of these ethylene-vinyl acetate copolymers or a mixture of ethylene-vinyl acetate copolymers is replaced with polyolefin to obtain a vinyl acetate content of 30% by weight or more. 120 to 250 parts by weight of the inorganic hydrate surface-treated with (b) a silane coupling agent, to 100 parts by weight of the admixture,
(C) 5 to 70 parts by weight of amorphous silica, carbon black or a mixture thereof, and (d) 0.5 to 1 of epoxy resin
A flame-retardant resin composition comprising 0 parts by weight.