JPH06336536A - Flame retardant, flame-retardant resin composition, and production of flame-retardant foam - Google Patents

Abstract

PURPOSE:To obtain a flame-retardant resin composition being excellent in flame retardancy, not generating any noxious halogen gases when burnt and having excellent modability and to provide a process for producing a flame- retardant foam having excellent frame retardancy and fine closed cells. CONSTITUTION:This flame retardant composition comprises polyethylene or an ethylene/vinyl acetate copolymer (EVA) as the resin component and phenylphosphonic acid or diphenylphosphinic acid as the flame retardant. When an ethylene/vinyl acetate copolymer (EVA) is used as the resin component, the flame retardant composition contains phenylphosphonic acid or diphynylphosphinic acid in combination with a hydrated metal oxide. Another flame-retardant resin composition is prepared by adding a melamine derivative to any one of the flame retardant compositions. The production process comprises adding an azodicarbonamide blowing agent to any one of the resin compositions, molding the resulting mixture into a sheet, crosslinking the sheet by irradiation with electron beams, and foaming the sheet by heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame retardant, a flame retardant resin composition and a method for producing a flame retardant foam.

[0002]

2. Description of the Related Art Conventionally, there has been a strong demand for flame-retardant plastic materials for applications such as electric wires for electric power plants, cables, electric wires for vehicles and electric wires for cabins in case of fire. Further, it is demanded that the flame-retardant plastic material is not only flame-retardant but also does not generate a halogen-based gas which is harmful to the human body during a fire.

As such a flame-retardant plastic material, it has been reported that polyethylene or ethylene-vinyl acetate copolymer contains an inorganic flame retardant such as aluminum hydroxide (Japanese Patent Laid-Open No. 61-36343). Gazette).
Further, as the flame-retardant resin foam, a foam obtained by foaming a composition comprising a polyolefin resin and an inorganic flame retardant such as aluminum oxide has been reported (JP-A-3-269).
No. 029 publication).

[0004]

However, the flame-retardant resin composition according to Japanese Patent Laid-Open No. 61-36343 needs to contain a large amount of an inorganic flame retardant, and when it is formed into a molded product, it has a high mechanical strength. , Especially the performance related to elongation is poor,
When used as a coating material or the like, it was not practically usable.

Further, the foam described in JP-A-3-269029 needs to use a large amount of an inorganic flame retardant,
As a result, there is a problem that it is difficult to obtain a foam having a fine closed cell structure which affects the foamability.

The object of the present invention is to provide a flame retardant having excellent flame retardancy and to generate a toxic halogenated gas at the time of burning. It is to provide a flame-retardant resin composition which is excellent in moldability without any use, and a method for producing a foam having a fine closed cell structure made of the flame-retardant resin composition.

[0007]

The flame retardant of the present invention comprises an arylphosphonic acid or a diarylphosphinic acid. The arylphosphonic acid is a compound represented by ArP (O) (OH) ₂ (in the formula, Ar represents an aryl group, and examples thereof include a phenyl group, a tolyl group, and a xylenyl group), and examples thereof include phenylphosphone. Acid, tolylphosphonic acid,
Examples include xylenylphosphonic acid and the like.

The above-mentioned diarylphosphinic acid means Ar ₂
A compound represented by P (O) OH (in the formula, Ar represents an aryl group, and examples thereof include a phenyl group, a tolyl group, and a xylenyl group), and examples thereof include diphenylphosphinic acid and
Examples thereof include ditolylphosphinic acid, dixylenylphosphinic acid, tolylphenylphosphinic acid, xylenylphenylphosphinic acid, and xylenyltolylphosphinic acid.

The second aspect of the present invention comprises a polyolefin resin and the above flame-retardant resin. Examples of the polyolefin resin include α-such as polyethylene, polypropylene and polybutene.
Olefins, ethylene-propylene copolymers, ethylene-propylene-diene terpolymers, ethylene-ethyl acrylate copolymers, ethylene-butene copolymers, ethylene-butene diene terpolymers, ethylene-vinyl acetate copolymers, etc. These may be used alone or in combination of two or more.

If the amount of the flame retardant added is too small, the flame retardancy will not be exhibited, and if it is too large, the elongation of the resin composition will decrease and the moldability will decrease, so the polyolefin resin 100
1 to 50 parts by weight is preferable with respect to parts by weight.

The third aspect of the present invention is a flame-retardant resin composition to which a melamine derivative is further added. As the melamine derivative, for example, melamine, melamine cyanurate,
Examples include melamine phosphate.

When the amount of the melamine derivative added is small, the synergistic effect with the flame retardant is small, and when it is too large, the elongation of the resin composition is lowered and the moldability is lowered. , 1 to 50 parts by weight is preferable.

4 of the present invention is a flame-retardant resin composition comprising an ethylene-vinyl acetate copolymer resin, the flame retardant according to claim 1 and a hydrated metal oxide.

The ethylene-vinyl acetate copolymer resin is not particularly limited as long as it is a polymer obtained by copolymerizing ethylene and vinyl acetate (usually called EVA). As the resin composition, the above ethylene-
The vinyl acetate copolymer resin may be used alone, or an ethylene-vinyl acetate copolymer resin and a mixture of one or more polyolefin resins may be used, but the vinyl acetate content in the resin is 5 in view of moldability. It is preferably about 20% by weight.

The vinyl acetate content is 5% by weight of the total resin content.
When the amount is less than the above, the dispersibility of the flame retardant other than the resin component is deteriorated, and when it exceeds 20% by weight, the tackiness of the surface of the molded product is increased and the moldability is deteriorated, and free acetic acid is generated during melt kneading This is because it is easy and the physical properties of the obtained resin composition are deteriorated.

When the amount of the arylphosphonic acid or diarylphosphinic acid which is a flame retardant is reduced, the flame retardancy is not exhibited, and when the amount is too high, the elongation of the resin composition is deteriorated when used in combination with a hydrated metal oxide. Therefore, the moldability is deteriorated, so 1 to 50 parts by weight is preferable to 100 parts by weight of the ethylene-vinyl acetate copolymer resin.

Examples of hydrated metal oxides include calcium hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium hydroxide, barium hydroxide, etc., which may be used alone. However, it is also possible to use two or more types in combination. Among them, aluminum hydroxide and magnesium hydroxide are particularly preferable, and by using them in combination, a further flame retardant effect can be obtained.

If the amount of the hydrated metal oxide added is small, the synergistic effect with the flame retardant composed of arylphosphonic acid or diarylphosphinic acid is small, and if it is too large, the elongation of the resin composition decreases and the moldability decreases. Therefore, 50 parts by weight per 100 parts by weight of ethylene-vinyl acetate copolymer resin
˜200 parts by weight is preferred.

The fifth aspect of the present invention is a flame-retardant resin composition further containing a melamine derivative. Examples of the melamine derivative include melamine, melamine cyanurate, and melamine phosphate, as in the case of the third aspect of the invention. When the addition amount of the melamine derivative is small, the synergistic effect with the flame retardant is small, and when the addition amount is too large, the elongation of the resin composition decreases and the moldability decreases, so 100 parts by weight of the ethylene-vinyl acetate copolymer resin is used. On the other hand, 1 to 50 parts by weight is preferable.

In addition to the above components, a polyhydric alcohol may be added to the system to which the arylphosphonic acid is added as a flame retardant. Examples of the polyhydric alcohol include pentaerythritol, arabitol, sorbitol, inositol, resosinol and the like. If the amount of the polyhydric alcohol added is too small or too large, it is difficult to obtain the effect of addition, so 0.05 to 0.3 parts by weight is preferable with respect to 1 part by weight of the arylphosphonic acid.

In the flame-retardant resin composition of the present invention, if necessary, an antioxidant, a lubricant, a softener, a dispersant,
Processing aids such as carbon black and surface treatment agents for hydrated metal oxides may be added as appropriate. The flame-retardant resin composition of the present invention has a high flame-retardant property while maintaining good mechanical strength, in particular, elongation property, and does not generate a halogenated gas at the time of burning, so that it is an extremely safe plastic material. Although it can be provided for a wide variety of uses, it is particularly suitable for a film molded product.

Finally, the sixth aspect of the present invention is the above-mentioned claim 2.
A method for producing a flame-retardant foam obtained by mixing a flame-retardant resin composition selected from Nos. 5 to 5 with a foaming agent, crosslinking the mixture with ionizing radiation, and then heat-foaming the mixture.

The amount of the foaming agent added varies depending on the expansion ratio of the foam, but is usually 15 to 3 with respect to 100 parts by weight of the resin composition.
0 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 ammonium bicarbonate.

As the ionizing radiation, electron rays, γ rays,
X rays, neutron rays and the like can be mentioned, but electron rays are preferable, and the irradiation dose thereof is usually in the range of 1 to 10 megarads.

The flame-retardant resin composition of the present invention can be obtained by uniformly kneading the above components using a kneading device such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader mixer, or a roll. . Then, the obtained mixture is used to form a sheet. The obtained sheet-shaped molded product is irradiated with ionizing radiation to crosslink the resin component, and then heated in a heating furnace to obtain a flame-retardant foam. These foaming steps can be carried out batchwise or continuously as required.

The flame-retardant foam obtained by the production method of the present invention has a high flame-retardant property while maintaining a heat insulating function as a foam, and is used for building materials, transportation equipment such as automobiles, packaging materials, household daily necessities. , And can be used for a wide range of other purposes.

[0027]

According to the present invention, by using an arylphosphonic acid or a diarylphosphinic acid as a flame retardant, it is possible to obtain a flame retardant effect on a resin material as a substitute for an inorganic flame retardant. Further, the flame-retardant resin composition of the present invention has excellent flame retardancy because an arylphosphonic acid or a diarylphosphinic acid is added as a flame retardant to a polyolefin resin, and unlike an inorganic flame retardant,
The affinity between the resin component and the flame retardant is high. further,
Since neither resin nor flame retardant contains halogen,
No halogenated gas is generated during combustion.

When an ethylene-vinyl acetate copolymer is used as the resin component, even if a hydrated metal oxide is added to some extent in addition to the arylphosphonic acid or diarylphosphinic acid, the affinity with the resin component is increased. Since it can be maintained, the flame retardant effect can be further improved while ensuring moldability. Furthermore, by adding a melamine derivative to the above flame retardant resin composition, a further flame retardant effect can be obtained. Further, according to the method for producing a flame-retardant foam of the present invention, the resin film elongation rate of the flame-retardant resin composition to be foamed is improved, so that the bubble film is not broken during foaming. As a result, it is possible to obtain a foam having flame retardancy while ensuring a fine independent foam structure.

[0029]

EXAMPLES Examples of the present invention will be described. Example 1
13 and Comparative Examples 1 to 9 (Tables 1 to 4) using a Labo Plastomill at 140 ° C. and 60 rp.
A flame-retardant resin composition was obtained by melt-kneading at m for 5 minutes. As resin component, low density polyethylene (LDP
E) [density 0.92, melt index 3.4], ethylene-vinyl acetate copolymer resin (EVA) [vinyl acetate content 19%, density 0.92, melt index 2.5] Phenylphosphonic acid as a flame retardant,
Diphenylphosphinic acid [both manufactured by Wako Pure Chemical Industries, Ltd.] was used.

Further, as other additives, melamine [manufactured by Nissan Chemical Industries, Ltd.], melamine cyanurate [MC6
10, manufactured by Nissan Chemical Industries, Ltd.], aluminum hydroxide [B703S, manufactured by Nippon Light Metal Co., Ltd.], magnesium hydroxide [Kisuma 54A, manufactured by Kyowa Chemical Industry Co., Ltd.], pentaerythritol [Wako Pure Chemical Industries, Ltd.] ], Decabromophenyl oxide (DBDPO) [AFR-1021, Asahi Glass Co., Ltd.] and antimony trioxide [Otsuka Chemical Co., Ltd.]
Manufactured] was used.

The resin composition thus obtained is molded at a molding temperature of 140 ° C.
Was molded into a sheet having a thickness of 3.0 mm, and the pressed sheet-shaped molded product was evaluated for flame retardancy and elongation (%) by the test method described below. Flame-retardant test : The flame-retardant property was evaluated by measuring the oxygen index with an A-1 test piece (150 mm × 6.5 mm, thickness 3.0 mm) according to JIS-K7201.

The growth rate: dumbbell test piece (10mm ×
2.5 mm, thickness 1.0 mm) was prepared, and the elongation percentage with respect to the original length at the time point when the test piece broke at 23 ° C., relative humidity 50% and tensile speed 200 mm / min was evaluated. Tables 1 to 4 show the evaluation results of various flame-retardant resin composition samples performed as described above.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

The flame-retardant resin compositions shown in Examples 14 to 22 and Comparative Examples 10 to 16 (Tables 5 to 7) were used as a foaming agent.
An unfoamed flame-retardant resin composition was obtained by melt-kneading the mixture of azodicarbonamide with a Labo Plastomill at 140 ° C. and 60 rpm for 5 minutes. The unfoamed flame-retardant resin composition thus obtained is pressed at a molding temperature of 140 ° C. to be molded into a sheet having a thickness of 2.5 mm, and then the sheet has an absorbed dose of 3.0 using an electron beam accelerator. A dose equivalent to megarads was applied to crosslink. further,
A sheet of flame-retardant foam was obtained by heating this sheet in an oven at 230 ° C.

The flame retardancy of the obtained flame retardant foam sheet was evaluated according to JIS-K7201. Furthermore, as the expansion ratio of the foam sheet, the reciprocal of the density (cc /
The evaluation was performed by using g) as a substitute characteristic value. The results are shown in Tables 5-7.

[0039]

[Table 5]

[0040]

[Table 6]

[0041]

[Table 7]

[0042]

As described above in detail, according to the present invention,
By using arylphosphonic acid or diarylphosphinic acid, an effect as an organic flame retardant instead of an inorganic one can be obtained. Therefore, while using a polyethylene resin or ethylene-vinyl acetate copolymer as the resin component and adding arylphosphonic acid or diarylphosphinic acid as a flame retardant, while maintaining good elongation as a mechanical property, As a flame-retardant resin material that has excellent flame retardancy and does not generate toxic halogenated gas when burned, it can be applied to a wide range of applications.

Further, according to the method for producing a flame-retardant foam of the present invention, it is possible to obtain a fine independent foam while the flame retardant is added to the resin component used. As a result, the flame-retardant foam obtained by the production method of the present invention has excellent flame retardancy while having a function as a foam, and does not generate a toxic halogenated gas during combustion, which is extremely safe and heat-insulating. As a foam having properties such as heat resistance, light weight, and electric insulation, it can be applied to a wide range of applications.

Claims (6)

[Claims] 1. A flame retardant comprising an arylphosphonic acid or a diarylphosphinic acid. 2. A flame-retardant resin composition comprising a polyolefin resin and the flame retardant according to claim 1. 3. The flame-retardant resin composition according to claim 2, further comprising a melamine derivative. 4. A flame-retardant resin composition comprising an ethylene-vinyl acetate copolymer resin, the flame retardant according to claim 1, and a hydrated metal oxide. 5. The flame-retardant resin composition according to claim 4, further comprising a melamine derivative. 6. A flame-retardant foam produced by mixing a flame-retardant resin composition selected from claims 2 to 5 with a foaming agent, cross-linking with ionizing radiation, and then heat-foaming. Method.