JP3308633B2 - Foamable flame-retardant resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamable flame-retardant resin composition.

[0002]

2. Description of the Related Art Polyolefin resin foams are inherently flammable foams, but in recent years, their performance has been required as a flame-retardant material in accordance with the expansion of applications, and flame-retardant treatment has been performed by various methods. Have been. As a method of the flame retarding treatment, a method of adding a halogen compound to a polyolefin-based resin and foaming the same was generally used. The polyolefin-based resin foam obtained by this method is excellent in flame retardancy and moldability, and the strength of a molded article obtained by using the polyolefin-based resin foam is small. There is a drawback that gas is generated and corrodes the equipment and harms the human body.

In order to solve the above-mentioned drawbacks, Japanese Patent Laid-Open Publication No.
No. 5,171, and JP-A-3-269029, an inorganic flame retardant such as aluminum hydroxide, magnesium hydroxide, or basic magnesium carbonate is added.
Flame-retardant resin foams that do not generate halogen-based gas during combustion have been proposed, but in order to impart sufficient flame retardancy to polyolefin-based resin foams that are inherently flammable, a large amount of inorganic flame retardants must be used. It has to be added, and there is a drawback that the foamability of the resulting flame-retardant resin foam is reduced.

Japanese Patent Application Laid-Open No. 2-187434 discloses a flame-retardant foamed sheet in which red phosphorus exhibiting a flame-retardant effect is added in addition to an inorganic flame retardant, so that the amount of the inorganic flame retardant added is reduced. However, in order to obtain sufficient flame retardancy, it is necessary to add a large amount of red phosphorus, and therefore, there is a disadvantage that the foamability of the obtained flame-retardant foam sheet is reduced.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to provide a foamable flame-retardant resin composition capable of obtaining a foam having excellent flame retardancy and foamability.

[0006]

Polyolefin resin matrix used in the present invention, in order to solve the above-mentioned object, et styrene - vinyl acetate copolymer alone or 50% or more by weight of ethylene -
It is a mixture of a vinyl acetate copolymer and one or more other polyolefin resins.

When the content of vinyl acetate in the polyolefin resin matrix is reduced, the compatibility of the inorganic flame retardant with the polyolefin resin matrix is reduced. When the content is increased, the vinyl flame retardant resin composition of the present invention is obtained. 5-20% by weight because the moldability of the foam decreases
Is limited to

When the polyolefin resin matrix is a mixture of an ethylene-vinyl acetate copolymer and one or more other polyolefin resins, the content of vinyl acetate in the whole mixture is 5 to 20% by weight. The ethylene-vinyl acetate copolymer preferably used includes those having a vinyl acetate content of 10 to 25% by weight.

In the above polyolefin resin matrix, the polyolefin resin used together with the ethylene-vinyl acetate copolymer includes, for example, polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-propylene-diene terpolymer, ethylene-ethyl An acrylate copolymer, an ethylene-butene copolymer, an ethylene-butene-diene terpolymer and the like can be mentioned.

The inorganic flame retardant used in the present invention includes, for example, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium hydroxide, barium hydroxide and the like. Magnesium hydroxide, which may be used alone or in combination.

When the amount of the inorganic flame retardant is small, the flame retardancy of the foam obtained from the foamable flame-retardant resin composition of the present invention decreases, and when the amount is large, the foamable flame-retardant resin composition of the present invention increases. Since the strength of the foam obtained from is reduced, 50 parts by weight based on 100 parts by weight of the polyolefin resin matrix is used.
It is limited to ~ 200 parts by weight.

When the amount of red phosphorus used in the present invention decreases, the flame retardancy of the foam obtained from the foamable flame-retardant resin composition of the present invention decreases. Since the strength of the foam obtained from the resin composition decreases, the amount is limited to 5 to 50 parts by weight based on 100 parts by weight of the polyolefin resin matrix.

Although the above-mentioned red phosphorus may be used as it is, it has a high hygroscopicity and a high risk of spontaneous ignition. Therefore, red phosphorus whose particle surface is coated with a resin such as a phenol resin or a melamine resin is used. You may be.

The melamine compound used in the present invention includes, for example, melamine, melamine cyanurate,
Melamine phosphate and the like. When the amount of the melamine compound is reduced, the flame retardancy of the foam obtained from the foamable flame-retardant resin composition of the present invention decreases, and when the amount increases, the foam obtained from the foamable flame-retardant resin composition of the present invention increases Of the polyolefin resin matrix 1
It is limited to 5 to 50 parts by weight based on 00 parts by weight.

The polyhydric alcohol used in the present invention includes, for example, pentaerythritol, dipentaerythritol, tripentaerythritol, arabitol, sorbitol, inositol, resorcinol and the like.

Regardless of whether the amount of the polyhydric alcohol is small or large, the flame retardancy of the foam obtained from the foamable flame-retardant resin composition of the present invention is reduced. Parts by weight is limited to 1 to 15 parts by weight.

Examples of the foaming agent used in the present invention include organic foaming agents such as azodicarbonamide and N, N-dinitrosopentamethylenetetramine, and inorganic foaming agents such as sodium bicarbonate and ammonium carbonate. No. When the amount of the foaming agent is reduced, the foamability of the foam obtained from the foamable flame-retardant resin composition of the present invention decreases, and the foaming agent obtained from the foamable flame-retardant resin composition of the present invention increases when the amount increases. Since the strength is reduced, it is limited to 15 to 30 parts by weight.

The composition of the foamable flame-retardant resin composition of the present invention is as described above. However, as long as the physical properties of the foamable flame-retardant resin composition are not impaired, a crosslinking agent, an antioxidant, a lubricant, and a softening agent are used. Agents, dispersants, processing aids and the like may be added.

The foamable flame-retardant resin composition of the present invention comprises a polyolefin resin matrix, an inorganic flame retardant, red phosphorus,
It is obtained by supplying a melamine compound, a polyhydric alcohol and a foaming agent to, for example, a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader mixer, a roll, or the like and melt-kneading them.

As a method for producing a foam using the foamable flame-retardant resin composition, for example, the foamable flame-retardant resin composition is formed into a sheet, and the resulting foamable flame-retardant resin sheet is ionized. Irradiating with radiating radiation to form a crosslinkable foamable flame-retardant resin sheet, and then supplying the obtained crosslinkable foamable flame-retardant resin sheet to a foaming furnace for foaming by heating.

The ionizing radiation includes, for example, an electron beam, a γ-ray, an X-ray, a neutron beam and the like, preferably an electron beam. The irradiation amount of the ionizing radiation is reduced, the strength of the foam obtained from the foamable flame-retardant resin composition of the present invention is reduced, and when the irradiation amount is increased, the foam obtained from the foamable flame-retardant resin composition of the present invention is increased. Since the foaming property is reduced, 1-1
0 Mrad is preferred.

[0022]

Next, embodiments of the present invention will be described. In addition,
“Parts” means “parts by weight”. Examples 1 to 3 and Comparative Examples 1 to 4 Ethylene of a predetermined amount (part) shown in Table 1 having a vinyl acetate content of 19% by weight, a density of 0.94 g / cm ³ , and a melt index of 2.5 g / 10 min. Vinyl acetate copolymer (manufactured by Mitsui Polychemicals, trade name: Evaflex EV46)
0); low-density polyethylene (manufactured by Mitsubishi Yuka Co., trade name: Yucalon YK-40) having a density of 0.92 g / cm ³ and a melt index of 3.4 g / 10 min; aluminum hydroxide (manufactured by Nippon Light Metal Co., Ltd.) : B703S); magnesium hydroxide (Kyowa Chemical Industry Co., Ltd., trade name: Kisuma 5)
A); red phosphorus (manufactured by Rin Kagaku Kogyo Co., Ltd., trade name: Nova Red 120); melamine (manufactured by Nissan Kagaku Kogyo Co., Ltd.);
0); pentaerythritol (manufactured by Wako Pure Chemical Industries); decabromodiphenyl ether (manufactured by Asahi Glass Co., Ltd., trade name: A)
FR-1021); antimony trioxide (manufactured by Sangoku Seisakusho)
And azodicarbonamide were supplied to Labo Plastomill and melt-kneaded at a temperature of 140 ° C. and 60 rpm for 5 minutes to obtain a foamable flame-retardant resin composition, and the obtained foamable flame-retardant resin composition was heated at a temperature of 140 ° C. Pressing was performed to obtain a foamable flame-retardant resin sheet having a thickness of 2.5 mm.

The obtained foamable flame-retardant resin sheet is irradiated with 3 Mrad of ionizing radiation and crosslinked to obtain a foamable flame-retardant resin crosslinked sheet, and the obtained foamable flame-retardant resin crosslinked sheet is placed in an oven. Foaming was performed by heating and foaming at a temperature of 230 ° C.

[0024]

[Table 1]

The flame retardancy of the foams obtained in Examples 1 to 3 and Comparative Examples 1 to 4 was evaluated by measuring the oxygen index in accordance with JIS K7201. In addition, the expansion ratio and the thickness of the foam were measured to evaluate the expandability, and the obtained results are shown in Table 2.

[0026]

[Table 2]

[0027]

As described above, the composition of the foamable flame-retardant resin composition of the present invention is excellent in flame retardancy and foamability.

Claims (1)

(57) [Claims] An ethylene-vinyl acetate copolymer alone or
50% by weight or more of ethylene-vinyl acetate copolymer and one kind
Consisting of a mixture with the above other polyolefin resin,
And the content is 100 parts by weight 5 to 20 wt% of the polyolefin resin matrix of vinyl acetic acid, 50-200 parts by weight inorganic flame retardants, red phosphorus 5 to 50 parts by weight, the melamine compound 5-50 parts by weight, multi A foamable flame-retardant resin composition comprising 1 to 15 parts by weight of a polyhydric alcohol and 15 to 30 parts by weight of a foaming agent.