JP3504991B2 - Flame retardant thermoplastic resin composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant thermoplastic resin composition. 2. Description of the Related Art Many thermoplastic resins are inherently flammable. In recent years, it has been required to impart flame-retardant properties with the expansion of applications for use. Is being processed. As a method of making a thermoplastic resin flame-retardant, a method of adding a halogen-containing compound is generally performed. In addition to being able to certainly impart a high degree of flame retardancy by adding a halogen-containing compound, Deterioration of molding processability and reduction of mechanical strength of molded products are relatively small, but a large amount of smoke may be generated during molding and combustion, and special equipment for preventing corrosion of equipment is required. there were.
Therefore, there is a strong demand for a method for imparting flame retardancy without using a halogen-containing compound. [0003] Under these circumstances, studies on resin flame retardation by adding hydrated metal oxides that do not generate gas during combustion, such as aluminum hydroxide, magnesium hydroxide, and basic magnesium carbonate, have been actively conducted. It has become to be. However, in order to impart sufficient flame retardancy to a flammable thermoplastic resin using only these hydrated metal oxides, it is necessary to add a large amount of hydrated metal oxides. However, there is a problem that the mechanical strength of the resulting molded article is significantly reduced. As a method of imparting flame retardancy without using a halogen-containing compound, for example, Japanese Patent Application Laid-Open No.
No. 3 and JP-A-3-41164 disclose a method in which thermally expandable graphite is solely added as a flame retardant to a thermoplastic resin. However, in order to impart sufficient flame retardancy, a large amount of graphite is used. However, there is a problem that a large amount of expanded graphite is scattered during combustion. Further, for example, Japanese Patent Application Laid-Open No. 62-275138
Japanese Patent Application Laid-Open Publication No. H11-176,086 discloses a method of making a thermoplastic resin flame-retardant by simultaneously adding heat-expandable graphite and red phosphorus to the thermoplastic resin. However, since red phosphorus has a risk of ignition and the like, it is actually used. We had to pay close attention to this. [0006] For example, Japanese Patent Application Laid-Open No. 6-25476 discloses a method of making a thermoplastic resin flame-retardant by adding a two-component mixed flame retardant of thermally expandable graphite and ammonium polyphosphate. However, in this method, since the heat-expandable graphite obtained by treating with an inorganic acid and a strong oxidizing agent is used without being subjected to a neutralization treatment, when this is used as it is, a thermoplastic resin composition is used. Of the machine, and the machine may be corroded during kneading and molding. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and has as its object to provide a high flame-retardant performance without using any halogen-containing compound. An object of the present invention is to provide a flammable thermoplastic resin composition. The flame-retardant thermoplastic resin composition of the present invention comprises a thermoplastic resin and a mixture of a neutralized heat-expandable graphite and ammonium polyphosphate. The thermoplastic resin used in the present invention is not particularly limited as long as it can be heated and melt-molded.
Polyethylene resin, polypropylene resin, poly (1
-) Butene resins, polypentene resins, polystyrene resins, acrylonitrile-butadiene-styrene resins, polycarbonate resins, polyphenylene ether resins, vinyl chloride resins, and the like. As the polyethylene resin, any of an ethylene homopolymer, a copolymer containing ethylene as a main component, and a mixture thereof can be used. Ethylene and α-
Copolymers with olefins can be mentioned. As the α-olefin, propylene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene, 1-
Pentene and the like. Examples of the copolymer with a component other than the α-olefin include an ethylene-vinyl acetate copolymer, an ethylene-ethylene acrylate copolymer, and a graft copolymer thereof. As the polypropylene-based resin, any of propylene homopolymer, a copolymer containing propylene as a main component and a mixture thereof can be used. And a copolymer of propylene and an α-olefin. Examples of the α-olefin include ethylene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene, 1-pentene and the like. Examples of the acrylonitrile-butadiene-styrene resin include copolymers containing acrylonitrile, butadiene and styrene as main components, blends of homopolymers of these components, styrene-acrylonitrile copolymers and acrylonitrile-butadiene. Examples include a blend with a copolymer rubber, a graft polymer obtained by graft copolymerization of styrene and acrylonitrile in the presence of butadiene rubber latex or styrene-butadiene rubber latex. The polystyrene resin includes a polymer of a monomer of an α-substituted styrene such as styrene or α-methylstyrene or a monomer of a vinyl aromatic compound such as nucleus-substituted styrene such as vinyltoluene; Other monomers copolymerizable with the body, for example, acrylonitrile, (meth) acrylic acid, a copolymer of a methyl or ethyl ester thereof and a heterocyclic compound, or the α-substituted styrene monomer or Examples include a graft copolymer obtained by grafting a heterocyclic compound to a polymer of a vinyl aromatic compound monomer. As the heat-expandable graphite, conventionally known substances can be used. For example, powders such as natural flaky graphite, pyrolytic graphite, and quiche graphite can be used.
Treatment with inorganic acids such as concentrated sulfuric acid, nitric acid and selenic acid and strong oxidizing agents such as concentrated nitric acid, perchloric acid, perchlorate, permanganate, dichromate, hydrogen peroxide, etc. It is a crystalline compound that has been produced and maintains the layered structure of carbon. In the present invention, the heat-expandable graphite obtained by the above-mentioned acid treatment is used after being neutralized 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, for example, monomethylamine, dimethylamine, trimethylamine, ethylamine, propylamine, butylamine, and the like.As the alkali metal compound and the alkaline earth metal compound, potassium, sodium, calcium, barium, Examples include hydroxides, oxides, carbonates, sulfates, and organic acid salts of magnesium and the like. If the above-mentioned heat-expandable graphite is used without being subjected to a neutralization treatment, the stability of the resin composition is impaired, and corrosion occurs in a molding machine during kneading and molding, which is not preferable. If the particle size of the heat-expandable graphite is too small, the degree of expansion of the heat-expandable graphite is small and sufficient flame retardancy cannot be obtained. If the particle size is too large, the dispersibility when mixing and kneading with the polyolefin resin is reduced. Since the physical properties of the obtained molded article are deteriorated, the mesh size is preferably 20 to 200 mesh. Examples of the ammonium polyphosphates used in the present invention include ammonium polyphosphate, melamine-modified ammonium polyphosphate and the like, which may be used alone or in combination of two or more. The ammonium polyphosphates have a 2% weight loss temperature of 180 to 250 ° C. by thermogravimetric analysis from the viewpoint of improving flame retardancy.
Those having a% weight loss temperature in the range of 270 to 310 ° C are preferred. The 2% or 5% weight loss temperature was measured using a thermogravimetric analyzer (abbreviated as TGA) at a heating rate of 10 ° C. /
Min. Under the air flow of 200 ml / min.
This refers to the temperature at which the weight of a sample decreases by 2% by weight or 5% by weight when a 0 mg sample is heated from room temperature to 900 ° C. The mixing ratio of the neutralized heat-expandable graphite and ammonium polyphosphate is 1:10 by weight.
10 to 10: 1 is preferred. When the mixing ratio is out of the above range, there is almost no difference in flame retardancy between the case where the thermally expandable graphite and the ammonium polyphosphate are used alone. In the resin composition of the present invention, if the amount of the mixture of the neutralized heat-expandable graphite and the ammonium polyphosphate is too small, sufficient flame retardancy cannot be obtained. Since a foam cannot be obtained, the amount is limited to 5 to 200 parts by weight based on 100 parts by weight of the thermoplastic resin. A hydrated metal compound may be added to the resin composition as a flame retardant aid. Examples of the hydrated metal oxide include aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dawsonite, and the like. These may be used alone or in combination of two or more. In the above resin composition, the amount of the hydrated metal oxide used depends on the amounts of the thermally expandable graphite and ammonium polyphosphates added. Since the mechanical strength of
The amount is preferably 100 parts by weight or less based on 100 parts by weight of the thermoplastic resin. The above resin composition may further contain an antioxidant such as a phenol-based, amine-based or sulfur-based antioxidant, a metal harm inhibitor, a filler, an antistatic agent and a stabilizer as far as the physical properties are not impaired. , A cross-linking agent, a lubricant, a softening agent, a pigment and the like may be added. The above resin composition is prepared by mixing a thermoplastic resin, neutralized heat-expandable graphite, ammonium polyphosphate and other components with a single screw extruder, a twin screw extruder,
It is obtained by kneading using a kneading device such as a Banbury mixer, a kneader mixer or a roll. Next, an embodiment of the present invention will be described. (Examples 1 to 6, Comparative Examples 1 to 5 ) A predetermined amount of a polyolefin resin shown in Tables 1 and 2,
The neutralized heat-expandable graphite, ammonium polyphosphate, and other components were melt-kneaded at a molding temperature shown in Tables 1 and 2 using a Labo Plastomill to obtain a flame-retardant thermoplastic resin composition. The obtained flame-retardant thermoplastic resin composition was press-molded at the molding temperatures shown in Tables 1 and 2 to produce samples. No corrosion was observed in the cylinder, screw, etc. of the Labo Plastomill in the melt kneading. In addition,
The pH of the neutralized heat-expandable graphite was measured by a pH meter after charging 1 g of the heat-expandable graphite in 100 cc of pure water at 25 ° C. and stirring with a stirrer for 5 minutes.
It was 0. Using the samples obtained in the above Examples and Comparative Examples, the following performance tests were performed, and the results are shown in Tables 1 and 2. (A) Flame retardancy test A-1 test piece (150 in accordance with JIS K7201)
× 6.5 × 3 mm thickness), the oxygen index was evaluated as “O” when the oxygen index was 28 or more, and as “X” when the oxygen index was less than 28. (B) Scattering of graphite Regarding the scattering of graphite, x indicates that the expanded graphite scattered during the oxygen index measurement in (a), and ○ indicates that it did not. [Table 1] [Table 2] In Tables 1 and 2, the following components were used. PP: polypropylene (density = 0.90, MI = 1.
5) LDPE: low density polyethylene (density = 0.92, M
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 strength polystyrene (density = 1.06, MI
= 1.7)-Neutralized heat-expandable graphite: "CA-" manufactured by Nippon Kasei Co., Ltd.
60S ”, average particle size 60 mesh, ammonium polyphosphate (1): 2% weight loss temperature by Sumitomo Chemical“ Sumisafe P ”TGA 214 ° C, 5
% Weight loss temperature 294 ° C ・Ammonium polyphosphate (2 ): “Host manufactured by Hoechst
aflam-AP422 ”TGA 2% weight loss temperature 306
C., 5% weight loss temperature 334 ° C. The thermogravimetric analyzer “Type: TG / DTA320” manufactured by Seiko Electronics Co., Ltd. was used for TGA measurement. Density: g
/ Cm ³ , MI: g / 10 min. The composition of the flame-retardant thermoplastic resin composition of the present invention is as described above, and excellent flame retardancy can be imparted without using any halogen-containing compound. Since there is no generation of halogen-based gas during combustion or processing, it can be used for a wide range of applications requiring flame retardancy, such as in the field of building materials.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 1/00-101/16

Claims (1)

(57) [Claim 1] 100% by weight of a thermoplastic resin, a neutralized heat-expandable graphite, and a 2% weight loss temperature by thermogravimetric analysis of 180 to 250 ° C, and A flame-retardant thermoplastic resin composition comprising 5 to 200 parts by weight of a mixture with ammonium polyphosphate having a 5% weight loss temperature of 270 to 310 ° C.