JPH0873649A - Flame retardant thermoplastic resin composition - Google Patents

Abstract

PURPOSE: To obtain the subject resin composition, applicable to various thermoplastic resins without using a halogen-based compound and having remarkable flame retardancy and strength by blending a thermoplastic resin with a flame retardant comprising a thermally expandable graphite and red phosphorus in a specific proportion. CONSTITUTION: This flame retardant thermoplastic resin composition is obtained by blending 100 pts.wt. thermoplastic resin (e.g. polypropylene) with 5-150 pts.wt. total amount of a thermally expandable graphite and red phosphorus at a weight ratio of the thermally expandable graphite to red phosphorus within the range of (9:1) to (1:9) as a flame retardant and melt kneading the components using a laboratory plastomill, etc. The resultant composition is excellent in balance among mechanical properties such as strength and elongation in addition to remarkable flame retardancy without emitting toxic halogen-based gases and scattering the graphite even in burning or processing and applicable to various thermoplastic resins.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flame-retardant thermoplastic resin composition.

[0002]

2. Description of the Related Art Since many thermoplastic resins are inherently easy to burn, the performance as a flame-retardant material has been required with the expansion of their applications in recent years, and they have been subjected to flame-retardant treatment by various methods. Conventionally, a method of adding a halogen-containing compound has been generally used, but this method can give a high degree of flame retardancy, but since a large amount of gas is generated during processing and combustion, it corrodes equipment. Sexuality and toxicity to the human body are problems. Particularly in recent years, halogen-free flame-retardant materials have been strongly demanded in terms of safety.

Therefore, studies on flame retardancy of resins by adding hydrated metal oxides such as aluminum hydroxide, magnesium hydroxide, and basic magnesium carbonate which do not generate toxic gas during combustion have been actively conducted. . However, it is necessary to add a large amount in order to impart sufficient flame retardancy to a flammable thermoplastic resin composition only with a hydrated metal oxide, and as a result, the mechanical strength of the molded product is significantly reduced. However, there was a problem that it could not be put to practical use.

Further, in JP-A-3-41163 and JP-A-3-41164, thermal expansive graphite alone is used as a flame retardant in a thermoplastic resin, but in this case also sufficient flame retardancy is obtained. To give it, it is necessary to add a large amount. Further, when the thermally expandable graphite is used alone, there is a problem that a large amount of expanded graphite is scattered during combustion.

Further, in JP-A-58-67737, flame retardancy is imparted by simultaneously adding a hydrate of an inorganic metal compound, heat-expandable graphite and red phosphorus to a polyolefin resin. There is no description of resins other than polyolefin-based resins, and if a large amount of hydrates of inorganic metal compounds are used, the mechanical strength and elongation of the resulting molded article will decrease, and it will not There was a problem that the subsequent workability was lowered.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to effectively use various thermoplastic resins without using a halogen-based compound, and to achieve remarkable flame retardancy and It is intended to provide a flame-retardant thermoplastic resin composition having excellent mechanical properties.

[0007]

The thermoplastic resin used in the present invention is not particularly limited, and examples thereof include polypropylene resin, polyethylene resin, polystyrene resin, acrylonitrile-butadiene-styrene resin, poly (1-) Butene resin, polypentene resin, polycarbonate resin, polyphenylene ether resin, nylon resin, acrylic resin, polyamide resin, and the like. These may be used alone or in combination of two or more.

Examples of the polypropylene resin include a propylene homopolymer, a copolymer containing propylene as a main component, and a mixture thereof. Examples of the copolymer include propylene containing propylene as a main component.
Examples include α-olefin copolymers. Examples of the α-olefin include ethylene, 1-hexene, and 4
-Methyl-1-pentene, 1-octene, 1-butene,
1-pentene etc. are mentioned.

Examples of the polyethylene-based resin include ethylene homopolymers, copolymers containing ethylene as a main component, and mixtures thereof. Examples of the copolymers include ethylene-containing ethylene-based polymers. Examples include α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, and the like. Above α
-As the olefin, for example, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene, 1-
Penten etc. are mentioned.

Examples of the polystyrene resin include homopolymers of vinyl aromatic compounds, copolymers with other monomers copolymerizable therewith, and graft copolymers thereof. As the vinyl aromatic compound, styrene,
Examples include α-substituted styrenes such as α-methylstyrene and nuclear-substituted styrenes such as vinyltoluene. Examples of the other monomer copolymerizable with the vinyl aromatic compound include acrylonitrile, acrylic acid, methacrylic acid, and vinyl heterocyclic compounds such as methyl or ethyl ester thereof.

Examples of the acrylonitrile-butadiene-styrene resin include acrylonitrile, butadiene,
A copolymer containing styrene as a main component and a mixture thereof,
Examples thereof include a mixture of an acrylonitrile-styrene copolymer and an acrylonitrile-butadiene copolymer rubber, a copolymer obtained by graft-polymerizing styrene and acrylonitrile in the coexistence of a butadiene rubber latex or a styrene-butadiene rubber latex.

As the heat-expandable graphite used in the present invention, conventionally known ones can be used, and powders of natural scaly graphite, pyrolytic graphite, quiche graphite and the like are mixed with inorganic acids such as concentrated sulfuric acid, nitric acid and selenic acid. And a graphite intercalation compound obtained by treatment with a strong oxidizer such as concentrated nitric acid, perchloric acid, perchlorate, permanganate, dichromate, and hydrogen peroxide solution. It is a crystalline compound that maintains the layered structure. Further, it is preferable to use a product obtained by further neutralizing this with ammonia, an aliphatic lower amine, an alkali metal compound, an alkaline earth metal compound or the like.

Examples of the aliphatic lower amine include monomethylamine, dimethylamine, trimethylamine,
Examples thereof include ethylamine, propylamine and butylamine. Examples of the alkali metal compounds and alkaline earth metal compounds include hydroxides, oxides of potassium, sodium, calcium, barium, magnesium and the like,
Examples thereof include carbonates, sulfates and organic acid salts.

When the particle size of the heat-expandable graphite is small, the degree of expansion of the graphite is small, so that the flame retardancy is lowered. At that time, the dispersibility deteriorates and the physical properties decrease, so
0-200 mesh is preferred.

As the red phosphorus used in the present invention, commercially available red phosphorus may be used, but from the viewpoint of moisture resistance and safety (spontaneous ignition during kneading, etc.), the surface of the red phosphorus particles is made of resin. It is preferable to use a coated product.

In the present invention, the weight ratio of the heat-expandable graphite and red phosphorus is such that when the amount of the heat-expandable graphite is small, the sufficient flame retardant effect cannot be obtained. Of the thermal expansion graphite: red phosphorus =
It is limited to 9: 1 to 1: 9, preferably 5: 1 to 1: 5, and more preferably 3: 1 to 1: 3.

The amounts of the above-mentioned thermally expandable graphite and red phosphorus are
If the amount is reduced, a sufficient flame retardant effect cannot be obtained, and if the amount is increased, mechanical properties such as strength and elongation are deteriorated and it cannot be used.
5 to 15 in total with respect to 100 parts by weight of the thermoplastic resin
Limited to 0 parts by weight.

Further, in the present invention, a phenol-based, amine-based, sulfur-based, etc. antioxidant, a metal damage inhibitor, a filler, and the like may be added, if necessary, as long as the physical properties of the composition are not impaired.
Antistatic agents, stabilizers, crosslinking agents, lubricants, softeners, pigments and the like may be added.

The flame-retardant thermoplastic resin composition of the present invention is obtained by kneading the above-mentioned components with a device such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader mixer, a roll and a Labo Plastomill. .

[0020]

EXAMPLES The present invention will be described below with reference to examples. (Examples and Comparative Examples) Each component was melt-kneaded using a Labo Plastomill at the compounding and molding temperatures shown in Tables 1 and 2,
A resin composition was obtained. The obtained resin composition was pressed at the indicated molding temperature to prepare a test piece. The flame retardancy of this test piece was evaluated according to JIS K7201. The test piece is an A-1 test piece (length 150 mm × width 6.
The oxygen index was measured as 5 mm × thickness 3.0 mm), and those having an oxygen index of 30 or more were evaluated as ⊚, those having an oxygen index of 28 or more and less than 30 were evaluated as ◯, and those having an oxygen index of less than 28 were evaluated as x. In addition, the presence or absence of graphite scattering during the evaluation of flame retardance was observed, and those in which expanded graphite did not scatter were evaluated as ◯, and those in which scattering did occur were evaluated as x. Further, the tensile properties were evaluated at room temperature according to JIS K 7113, and those having an elongation of 200% or more were evaluated as ◯, and those not having an elongation were evaluated as x. The above results are shown in Tables 1 and 2.

The components used in the examples and comparative examples shown in Tables 1 and 2 are as follows. PP: polypropylene, density = 0.90, MI (melt index) = 1.5 LDPE: low density polyethylene, density = 0.92, MI
= 3.4 EVA: ethylene-vinyl acetate copolymer, vinyl acetate content 19% by weight, density = 0.92, MI = 2.5 ABS: acrylonitrile-butadiene-styrene copolymer, density = 1.20, MI = 22 PSt: high density polystyrene, density = 1.06, MI =
1.7 Thermally expandable graphite: CA-60S (manufactured by Nippon Kasei Co.) Red phosphorus: Nova Red 120 (manufactured by Rin Kagaku Kogyo Co., Ltd.)

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

The flame-retardant thermoplastic resin composition of the present invention comprises
No toxic halogen-based gas is generated or graphite is scattered during combustion or processing, and in addition to outstanding flame retardancy, it has a good balance with mechanical properties such as strength and elongation, so it can be used in a wide range of applications. .

Claims (1)

[Claims] 1. A thermoplastic resin of 100 parts by weight and a total amount of thermally expandable graphite and red phosphorus of 5 to 150 parts by weight, wherein said thermally expandable graphite: red phosphorus (weight ratio) = 9: 1 to 1 : 9. A flame-retardant thermoplastic resin composition.