JPH0776295B2 - Flame-retardant resin composition and flame-retardant insulated wire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flame-retardant resin composition, and particularly to a high voltage used mainly for a high voltage circuit for a cathode ray tube electron gun portion of a television receiver. The present invention relates to a flame-retardant sheath material for electric wires.

(Prior Art) A high-voltage electric wire used for a high-voltage circuit for a cathode ray tube electron gun portion of a television receiver used in Japan has a conductor covered with an insulator mainly made of polyethylene. Various studies have been made on methods such as applying a flame-retardant sheath material to the outer layer to protect polyethylene inside. At present, the structure disclosed in Japanese Patent Publication No. 51-8465 is predominant.

According to the publication, specifically, the softening point 105 as an insulator is used.
Using polyethylene with a high softening point of ℃ or higher, it was used as an electric wire insulator that passed the operating temperature of 105 ℃ described in Subject 758 of the UL standard in the United States. Described is a double-coated structure in which a highly flame-retardant sheath material mainly composed of a graft copolymer obtained by graft-copolymerizing vinyl chloride with a polymer is described, and combined with the use of a polyethylene insulator having a high softening point. , High tracking resistance, high high voltage cut-through properties and large non-deformable wires are disclosed.

Further, as a more concrete form of such a flame-retardant sheath material, a structure disclosed in Japanese Patent Publication No. 52-41786 is known.

According to this technique, a graft copolymer obtained by graft-copolymerizing vinyl chloride with an ethylene-vinyl acetate copolymer is further used, and further, a mixture of one or more of antimony, arsenic, tin oxide or sulfide, and a molecular weight. 200-1
It has been disclosed to compound 500 inorganic halogen-containing organic compounds, inorganic fillers for sintering, specific inorganic and organic flame retardants and inorganic fillers, which makes the above-mentioned graft copolymer-only system insufficient. In addition, the continuous flame resistance against flame contact is improved.

Further, many other techniques for providing such a flame-retardant sheath material are known, and for example, a graft copolymer of chlorinated polyethylene and vinyl chloride is radically crosslinked or high energy ray crosslinked ( Japanese Patent Publication No. 53-47148) and a graft copolymer obtained by grafting vinyl chloride onto an ethylene-vinyl ester copolymer are compounded with chlorinated polyethylene (Japanese Patent Publication No. 54-14611). Antimony trioxide is mixed in the compound. Yes (Japanese Patent Publication No. 54-1461)
No. 2), chlorinated polyethylene is blended with a graft copolymer of chlorinated polyethylene and vinyl chloride (Japanese Patent Publication No. 54-15057), and chlorinated polyethylene is blended with a graft copolymer of chlorinated polyethylene and vinyl chloride ( JP-B-54-15057), blending an ethylene copolymer into a graft copolymer of chlorinated polyethylene and vinyl chloride (JP-B-54-15058), grafting vinyl chloride onto an ethylene-vinyl ester copolymer. In the graft copolymer, a metal borate and calcium carbonate are blended (Japanese Patent Publication No. 56-41654), and hydrated alumina is also blended (Japanese Patent Publication No. 56-41655), and a zinc compound is added to chlorinated polyethylene. And antimony, zircon, molybdenum oxide or sulfide (JP-B-61-34746).

(Problems to be solved by the invention) However, as described in these publications, these proposed conventional flame-retardant sheath materials have almost all of the high flame-retardant properties as the first priority and electrical characteristics. Since these are supplemented by the selection of polyethylene or the like as an insulator, electrical characteristics due to the sheath material used are not considered so much.

However, with the recent increase in size and functionality of electronic devices,
The electrical properties of the sheath material, especially at high temperatures, have become unignorable.

And, more specifically, the greatest issue was the insulating property of the sheath material in a use atmosphere of 60 ° C or higher.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and in addition to the conventional high flame retardancy, flame retardant with improved electrical characteristics at room temperature or higher. A resin composition and a flame-retardant insulated wire using the same are provided.

A feature of the present invention is that a graft copolymer (hereinafter abbreviated as a graftmer) obtained by graft-copolymerizing vinyl chloride with an ethylene-methacrylic acid lower alkyl ester copolymer is used.

That is, the present invention is: a resin material mainly comprising a graft copolymer (A) obtained by graft-copolymerizing an ethylene-methacrylic acid lower alkyl ester copolymer with vinyl chloride, a halogen-containing organic flame retardant (B) and an inorganic flame-retardant agent. The present invention relates to a flame-retardant resin composition containing a combustible agent (C) and an inorganic filler (D), and further, an insulating coating made of a composition mainly composed of polyethylene having a high softening point is formed on a conductor, Externally, a resin material mainly composed of a graft copolymer (A) obtained by graft copolymerizing vinyl chloride onto an ethylene-methacrylic acid lower alkyl ester copolymer, a halogen-containing organic flame retardant (B) and an inorganic flame retardant (C). ) And an inorganic filler (D) are mixed to provide a flame-retardant insulated electric wire coated with the flame-retardant resin composition.

The present invention will be described in more detail below.

The proportion of each constituent component of the graftmer (A) can be arbitrarily selected according to the purpose of use and the like, but in general,
Ethylene in the trunk polymer is composed of 40 to 95% by weight, preferably 50 to 90% by weight, lower methacrylic acid lower alkyl ester 5 to 60% by weight, preferably 10 to 50% by weight, and grafted to the above trunk polymer. The proportion of vinyl chloride to be copolymerized is 20 to 80% by weight, preferably 30 to 60% by weight.

Examples of the methacrylic acid lower alkyl ester that constitutes the above-mentioned trunk copolymer include methacrylic acid esters such as methyl, ethyl, and propyl, and the methyl ester is preferable.

In the present invention, the graftmer (A) may be used alone or as a mixture with another resin compatible with the graftmer (A).

In this case, if a compatible resin such as polyethylene, polypropylene, polyvinyl alcohol, vinyl chloride resin, or chlorinated polyethylene is added to the graftmer (A),
Adjustment of mechanical strength and flexibility, and improvement of flame retardancy and foam expansion can be expected.

From the viewpoint of mechanical strength, it is desirable that the graftmer (A) has a high degree of polymerization, for example, 1000 or more.

However, flame retardance is insufficient, it is difficult to maintain the foam expansion property, and flame and flame spread easily when the graftmer alone or in a mixed system with a compatible resin is used.

Therefore, in the present invention, it is necessary to blend an appropriate amount of the halogen-containing organic flame retardant (B), the inorganic flame retardant (C) and the inorganic filler (D).

As the halogen-containing organic flame retardant (B), tetrabromobutane, perchloropentacyclodecane, tetrabromobisphenol A, chlorinated paraffin, brominated triphenyl phosphate, decabromodiphenyl, decabromodiphenyl oxide, brominated epoxy, etc. Is typical, and aromatic halogen compounds such as decabromodiphenyl are more preferable in terms of heat resistance.

Typical examples of the inorganic flame retardant (C) include antimony, arsenic, tin oxide, and sulfide.
Antimony trioxide is particularly preferable. In order to maintain the durability of flame retardancy, the graft filler (A) is added to the inorganic filler (D).
Is preferably added, and as the inorganic filler (D), asbestos, talc, clay, mica, zinc borate,
Typical examples are aluminum hydroxide, calcium carbonate, barium sulfate, magnesium oxide and the like, with talc, clay and zinc borate being particularly preferred.

By adding the halogen-containing organic flame retardant (B) and the inorganic flame retardant (C) and the inorganic filler to the resin material mainly composed of the graft copolymer (A) of the present invention, the halogen-containing organic flame retardant Since it contains a combination of specific additives consisting mainly of a flame retardant (B), it exhibits high flame retardance that passes the VW-1 standard, and since a specific graft copolymer (A) is used, it is at room temperature or above, especially 60 Electrical properties such as volume resistivity in a high temperature atmosphere above ℃
It is significantly superior to the C-EVA graft copolymer.

Therefore, the halogen-containing organic flame retardant (B), the inorganic flame retardant (C), and the inorganic filler (D) may be blended in appropriate amounts within the range where the above effects can be obtained, but each component is added in an appropriate amount. Is preferred.

The addition amount of the components (B) to (D) can be adopted in a relatively wide range depending on the purpose of use, application, etc.

Further, the composition of the present invention may be colored with a heat stabilizer, an ultraviolet absorber, a cross-linking agent (including a peroxide type), another filler, a foaming agent, a lubricant, a dye, a pigment, etc., if necessary. Various organic and inorganic additives such as agents can be added.

For the production of the composition of the present invention, a single-screw extruder, a multi-screw extruder,
A Banbury mixer, a roll, a kneader, a heatable Henschel mixer type high-speed fluid mixer, or the like can be used, and each compounding component can be produced by melt-kneading at a temperature higher than the melting point of the thermoplastic resin.

For the use of the composition of the present invention, wire coating materials (particularly sheath materials) are particularly suitable, but flame-retardant materials such as injection molded products, tubes, extrusion molding, compression molding, rolling molding, stretch molding, foam molding, etc. It can also be applied to applications that require

When the composition of the present invention is used as an insulated wire particularly as a sheath material, an insulator is preferably formed on a conductor, preferably a polyethylene having a high softening point of an appropriate thickness or a flame-retardant material thereof (for example, chlorinated polyethylene). Or a blend of a flame retardant, etc.), if necessary, insulative coating in the form of its crosslinked body, and further, a sheath of the flame retardant composition containing the graftmer (A) of the present invention is applied to the outside.

The composition of the present invention may be crosslinked by ionizing radiation or the like, if necessary.

Specific examples of the high softening point polyethylene used as the insulator include what is called a medium pressure method, a low pressure method or a high density polyethylene having a softening point of 105 ° C. or higher.
When this polyethylene is used as a crosslinked product, it is preferable to perform irradiation with high-energy radiation.

By applying polyethylene having a high softening point as an insulator on the conductor, a flame-retardant insulated wire having significantly improved electrical characteristics at room temperature or higher can be obtained in combination with the selection of the sheath material.

(Function) A flame-retardant resin composition disclosed in Japanese Patent Publication No. 52-41786, which is the mainstream as a conventional sheath material, is made of ethylene-based resin.
Based on a vinyl acetate copolymer-based graft copolymer obtained by graft copolymerizing vinyl chloride,
Although various flame retardants and inorganic fillers are also added,
The electrical properties of this composition, like common insulating materials,
The volume resistivity decreased as the temperature increased, and when the atmosphere became a high temperature, the volume resistivity was below the limit value of 10 ¹¹ Ω · cm as an insulator.

On the other hand, it is surprising that the use of the graftmer of the present invention can maintain its insulating property even in a high temperature atmosphere, although its theoretical mechanism of action is not clear. We were able to develop a flame-retardant sheath material.

Furthermore, this graftmer alone cannot be said to have high flame retardancy, and it is necessary to perform flame retardation treatment by a method of adding various flame retardants and / or inorganic fillers disclosed in JP-B-52-41786. .

(Example) Hereinafter, the present invention will be described with reference to examples, but the invention is not limited thereto.

A flame-retardant composition having the weight ratio shown in Table 1 was kneaded with a 6-inch open roll and pressed at 150 ° C. to prepare a sheet-like sample having a thickness of 1 mm. This was irradiated with an electron beam (10 Mrad) to crosslink.

The temperature change of the volume resistivity of this sample was measured. The results are shown in Table 2. It can be seen that the insulating property of 10 ¹¹ Ω · cm is maintained even at a high temperature of 80 ° C.

(Comparative Example) A sample was prepared in the same manner as in the Example except for the flame retardant formulation, and the change in volume resistivity with temperature was measured. The results are also shown in Table 2.

It is less than 10 ¹¹ Ω · cm at 80 ° C, which means that it cannot be said to be insulating.

In addition, in the said flame-retardant composition, each graftmer used is as follows. Grafter 1: ethylene-methyl methacrylate copolymer VC graft amount-50% by weight, degree of polymerization: 1030 Grafter 2: ethylene-methylmethacrylate copolymer VC graft amount-45% by weight, degree of polymerization: 1480 Graftmer 3: ethylene- Methyl methacrylate copolymer VC graft amount-40% by weight, degree of polymerization: 1230 Grafter 4: VC grafter of ethylene-vinyl acetate copolymer (Sumigraft GF manufactured by Sumitomo Chemical Co., Ltd.) Note VC: Vinyl chloride Methyl methacrylate content: 38% by weight (Effects of the Invention) As described above, the flame-retardant resin composition of the present invention retains its insulating property even in a high temperature atmosphere, and therefore, for high voltage used in a high voltage circuit for TV CRT electron guns. When used as a sheath material for electric wires, shielded wires, and coaxial wires, it has the effect of maintaining excellent electrical characteristics.

Further, by using polyethylene having a high softening point as an insulator in combination with the sheath material, there is also an effect that a flame-retardant electric wire having excellent electrical characteristics at room temperature or higher can be obtained.

Claims (2)

[Claims] 1. A resin material mainly comprising a graft copolymer (A) obtained by graft-copolymerizing an ethylene-methacrylic acid lower alkyl ester copolymer with vinyl chloride, a halogen-containing organic flame retardant (B) and an inorganic flame retardant. A flame-retardant resin composition comprising (C) and an inorganic filler (D). 2. A graft obtained by applying an insulating coating made of a compound mainly composed of polyethylene having a high softening point on a conductor, and graft-copolymerizing vinyl chloride onto an ethylene-methacrylic acid lower alkyl ester copolymer on the outside thereof. A flame-retardant resin composition obtained by mixing a resin material mainly comprising a copolymer (A) with a halogen-containing organic flame retardant (B), an inorganic flame retardant (C) and an inorganic filler (D). Flammable insulated wire.