JP2002309098A - Flame-retardant resin composition and formed product thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retardant resin composition and its formed products each generating no halogen-based gas in their combustion, especially to provide formed products having good flame retardancy and mechanical strength. SOLUTION: This flame-retardant resin composition is obtained by compounding 80-200 pts.wt. magnesium hydroxide-based solid solution, 3-30 pts.wt. salt of an inorganic acid with melamine per 100 pts.wt. thermoplastic resin (ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-methacrylate copolymer, ethylene-methyl acrylate copolymer, liner low-density polyethylene and the like). And the other objective formed products comprising the composition are also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant resin composition which does not generate a halogen-based gas by burning, and a molded product thereof. In particular, the present invention relates to molded articles having both good flame retardancy and mechanical strength, for example, various extruded articles such as electric wires used in the fields of electronic devices and automobiles, and injection molded articles.

[0002]

2. Description of the Related Art Conventionally, thermoplastic resins have been used in a wide range of fields because of their excellent moldability, lightness, durability, and electrical insulation. However, since it is an organic material unlike an inorganic material represented by a metal, it has a drawback that it is inherently flammable. Since flame retardancy is indispensable from the viewpoint of fire prevention, a flame retardant resin composition in which various flame retardants are blended with a thermoplastic resin has been proposed and disclosed.

In order to impart flame retardancy to a thermoplastic resin,
It has been common practice to mix an organic halogen compound and antimony trioxide and utilize the chemical and physical synergistic effects of both. However, the resin composition containing an organic halogen-based compound has been regarded as a problem due to the corrosiveness of halogen-based gas generated at the time of combustion, molding, or incineration of a molded article.

[0004] In order to solve such a problem, there is a method of adding a hydrated metal oxide, but it has been necessary to add a large amount because of insufficient flame retardancy. Further, as described in, for example, "Polymer Digest", Vol. 51, 1 , page 61, 1999, a combination with various flame-retardant aids such as red phosphorus, a metal compound, and a nitrogen compound has been performed.

[0005]

The use of a melamine salt as a flame retardant is disclosed in Japanese Patent Publication No. 61-44095, and melamine phosphate is mentioned as an example of an organic phosphate. JP-A-7-330980 discloses a flame-retardant resin composition containing melamine or melamine cyanurate, a hydrated metal oxide and talc as essential flame retardants for nitrogen compounds. Properties and mechanical strength were not obtained. Japanese Patent No. 2885358 discloses the use of a magnesium hydroxide-based solid solution, but the addition amount is large and sufficient flame retardancy and mechanical strength performance have not been obtained. In recent years, further higher flame retardancy has been required.

[0006]

Means for Solving the Problems A first invention of the present invention is:
A flame-retardant resin composition comprising a thermoplastic resin (A) and a magnesium hydroxide-based solid solution (B) represented by the following general formula (I) and a salt of an inorganic acid and melamine (C). Mg _1-x M _x (OH) ₂ ... (I) (wherein, M represents at least one divalent metal ion selected from the group consisting of Mn, Fe, Co, Ni, Cu, and Zn; Is 0.001 ≦ x <0.5).

[0007] The second invention is a thermoplastic resin (A) 100
8 parts by weight of magnesium hydroxide solid solution (B)
0 to 200 parts by weight, salt of inorganic acid and melamine (C) 3 to 3
The flame-retardant resin composition according to the first invention, wherein 0 parts by weight are blended.

In a third aspect, the thermoplastic resin (A) is an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-methyl methacrylate copolymer, or an ethylene-methacrylic acid copolymer. The flame-retardant resin according to the first or second invention, characterized in that it is one selected from ethylene-methyl acrylate copolymer and linear low-density polyethylene or a mixture of two or more thereof. A composition.

In a fourth aspect of the present invention, (A) comprises at least a mixture of an ethylene-vinyl acetate copolymer (a1) and an ethylene-methyl methacrylate copolymer (a2), and the ratio is a1 / a2 = 0. The flame-retardant resin composition according to any one of the first to third inventions, which is 1 to 1.5.

A fifth invention is the flame-retardant resin composition according to any one of the first to fourth inventions, wherein (C) is melamine sulfate.

A sixth invention is a molded article obtained by using the flame-retardant resin composition according to any one of the first to fifth inventions.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The thermoplastic resin (A) used in the present invention is not particularly limited. For example, polyolefins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-
Ethylene copolymers such as methyl methacrylate (MMA) copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, and ethylene-α-olefin copolymer synthesized with a conventional catalyst or a metallocene catalyst Polyolefin elastomers such as linear low-density polyethylene, styrene-based copolymer, polyurethane elastomer, polyester elastomer, ethylene-propylene copolymer elastomer, thermoplastic elastomers such as polyamide elastomer and styrene-based elastomer, polyester, etc. No. These thermoplastic resins can be used alone or in combination of two or more.

In general, a flame-retardant thermoplastic resin tends to decrease in mechanical strength such as tensile strength and tensile elongation when the flame retardancy is increased. Copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate (MMA) copolymer, ethylene-methacrylic acid copolymer, ethylene-
The use of a thermoplastic resin composed of one or a mixture of two or more selected from ethylene copolymers such as ethylene copolymers such as methyl acrylate copolymer and linear low-density polyethylene results in flame retardancy. It is more preferable because a flame-retardant thermoplastic resin having both good properties and good mechanical strength can be obtained. If necessary, the above-mentioned thermoplastic resin can be used in combination with a mixture of these resins.

Among them, a mixture of an ethylene copolymer composed of an ethylene-vinyl acetate copolymer (a1) and an ethylene-methyl methacrylate copolymer (a2) has flame retardancy, mechanical strength and heat resistance. It is more preferable from the viewpoint of improvement, and it is particularly preferable that the ratio of a1 / a2 is 0.1 to 1.5.

When a copolymer of ethylene and an acid or an ester thereof represented by an ethylene-vinyl acetate copolymer or an ethylene-methyl methacrylate copolymer is used, if the amount of the acid or ester component is less than 6% by weight, the molding is carried out. The hardness of the product tends to be high, and if it is more than 50% by weight, the mechanical properties tend to decrease. Therefore, the acid or ester component is preferably in the range of 6 to 50% by weight from the viewpoint of balance between flame retardancy, mechanical strength and flexibility.

The magnesium hydroxide solid solution (B) used in the present invention is represented by the following general formula (I). Mg _1-x M _x (OH) ₂ ... (I) (wherein, M represents at least one divalent metal ion selected from the group consisting of Mn, Fe, Co, Ni, Cu, and Zn; Satisfies 0.001 ≦ x <0.5, and particularly preferably satisfies 0.002 ≦ x <0.4. A flame-retardant resin composition having both mechanical strength cannot be obtained.

The average particle diameter of the magnesium hydroxide-based solid solution (B) is determined by using a Coulter method particle and a particle size distribution analyzer,
Alternatively, it can be measured by a laser analysis / scattering particle size distribution analyzer. The average particle diameter obtained by any one of the above-mentioned measurement methods is preferably in the range of 0.1 to 10 μm. If the thickness is less than 0.1 μm, poor dispersion is likely to occur during melting and kneading with the resin, so that the flame retardant effect is not easily obtained.
If it is larger than 0 μm, the particles may be conspicuous in the resin composition, and the appearance may be significantly impaired.

In order to improve the dispersibility in a resin and easily exhibit an excellent flame-retardant effect, the magnesium hydroxide-based solid solution (B) of the present invention comprises a higher fatty acid such as stearic acid or oleic acid or its alkali. Dry treatment or wet treatment with metal salt, silane coupling agent, titanate coupling agent, anionic surfactant, phosphate ester, aluminum coupling agent, surface treatment agent such as polyhydric alcohol and fatty acid ester Is preferably performed. Magnesium hydroxide solid solution (B)
0.1 to 10 parts by weight of these surface treatment agents
It is preferably processed in parts by weight.

The mixing amount of the magnesium hydroxide-based solid solution (B) with respect to 100 parts by weight of the thermoplastic resin (A) is 80-2.
00 parts by weight is preferable, and 100 to 180 parts by weight is particularly preferable. If the amount is less than the above range, it is difficult to obtain flame retardancy. If the amount is too large, the mechanical strength of the flame retardant resin composition may be reduced.

The melamine salt (C) with an inorganic acid used in the present invention is a salt of melamine with one or more inorganic acids selected from nitric acid, sulfuric acid, polyphosphoric acid, boric acid, phosphorous acid and sulfurous acid. One or a combination of two or more of the above is also possible. The salt of inorganic acid and melamine (C) is prepared by adding a basic amount of melamine to water, adding a calculated amount of inorganic acid, heating and reacting, neutralizing to a melamine salt, filtering, drying,
Obtained through a pulverizing process.

The average particle diameter of the salt (C) of the inorganic acid and melamine is from 0.1 to 0.1 obtained by either a Coulter particle and a particle size distribution measuring device or a laser analysis / scattering type particle size distribution measuring device. Those having a range of 50 μm are preferably used.

The salt (C) of an inorganic acid and melamine has a lower solubility in water from the viewpoint of actual use conditions, for example, the problem of dew condensation on wallpaper, the weather resistance when the electric wire is used outdoors and the like. Has good flame retardancy and good appearance.
In particular, melamine sulfate is preferably used because of its excellent flame retardancy and low solubility in water.

The amount of the salt (C) of the inorganic acid and melamine is preferably 3 to 30 parts by weight based on 100 parts by weight of the thermoplastic resin (A). If the amount is less than 3 parts by weight, it is difficult to obtain the flame retardant effect, and if it exceeds 30 parts by weight, the mechanical strength may be reduced.

In the present invention, the magnesium hydroxide-based solid solution (B) and the inorganic acid and melamine salt (C) are used in combination.
The flame retardant effect is remarkably superior to that of a conventional metal hydroxide such as magnesium hydroxide alone or in combination with another flame retardant auxiliary. The reason for this is not clear, but in addition to the endothermic effect due to the dehydration of the magnesium hydroxide-based solid solution, the presence of divalent metal ions contributes to the formation of a carbonized layer. It is presumed that flame retardancy increases due to nitrogen release due to decomposition. In addition, when an ethylene-based copolymer, a linear low-density polyethylene, or a thermoplastic resin containing a mixture thereof is selected as the thermoplastic resin (A), the mechanical strength is dramatically improved, so severe difficulties are caused. It can also be used for molded products such as electric wires and electric parts that require fuel standards.

The flame-retardant resin composition of the present invention may contain, if necessary, various additives other than the above-mentioned components, such as antioxidants, ultraviolet absorbers, various dyes and pigments for coloring, crosslinking agents, In addition to a crosslinking aid, a foaming agent, a lubricant and the like, a flame retardant such as various metal salts can be contained.

The flame-retardant resin composition of the present invention is produced by melt-kneading the above components using a two-roll mill, a Banbury mixer, a kneader, a twin-screw kneader or the like.

Representative examples of the flame-retardant resin composition of the present invention include compounds and masterbatches.
In the case of a compound, the composition is as it is, and in the case of a master batch, a desired flame retardant concentration is obtained by appropriately diluting with a thermoplastic resin at the time of molding, and an extruder, a calender molding machine, a T-die molding machine, an injection molding machine or the like is used. To form a molded product.

Examples of the molded article of the present invention include various extruded articles such as electric wires, high-voltage electric wires, tubes and tapes used in the fields of electronic equipment and automobiles, injection molded articles, automobile interior materials, and films for building materials. And sheets, electric parts and the like. Further, these molded products can be subjected to secondary processing such as electron beam crosslinking or chemical crosslinking for the purpose of improving heat resistance and maintaining shape.

[0029]

EXAMPLES The present invention will be described below in detail with reference to examples, but the scope of the present invention is not limited to the examples unless it exceeds the gist. Hereinafter, “part” indicates “part by weight” and “%” indicates “% by weight”. Examples 1 to 9, Comparative Examples 1 to 6 A1: Ethylene-vinyl acetate copolymer (vinyl acetate = 2
A2: Ethylene-methyl methacrylate copolymer (MMA
A3: linear low-density polyethylene (MI = 2.1 / 10 m)
in., density = 0.91 g / cm ³ ) B1: To a magnesium hydroxide-based solid solution represented by the general formula Mg _0.98 Ni _0.02 (OH) ₂ , a 2 wt% oleic acid toluene solution (based on oleic acid) Magnesium hydroxide-based solid solution (average particle diameter 0.7 μm) sprayed with a 5-fold amount of toluene and subjected to surface treatment (dry surface treatment)
m) B2: magnesium hydroxide-based solid solution represented by the general formula Mg _0.95 Co _0.05 (OH) ₂ (average particle diameter 0.7 μm)
m) C1: Melamine sulfate (average particle size: 15 to 20 μm) Mg (OH) ₂ : Kisuma 5B (manufactured by Kyowa Chemical Industry Co., Ltd.) The mixture was melt-kneaded for 5 minutes with the two rolls set in Example 1 to obtain a flame-retardant resin composition. This was used to prepare a plate-like sample using a hot press at 200 ° C., and the following evaluation was performed.

As the evaluation of flame retardancy, a UL94 vertical combustion test method (test piece: 13 mm × 127 mm, thickness 3 mm,
An advanced flame retardancy test based on the number of tests n = 5) was performed. UL94 rating is 5VA, V0,
V1, V2, NG (not applicable) and V0 or higher were accepted. In Examples 7 to 9 and Comparative Examples 5 to 6, the combustion time (seconds) (total of n = 5) was determined. Each sample (n =
5) Pass was made within 60 seconds. Also, JIS K72
Oxygen index was measured according to No. 01.

The mechanical strength was measured in accordance with JIS K 6760 at a tensile speed of 200 mm / min. Rejected (x). Tables 1 and 2 show the above evaluation results.

[0032]

[Table 1]

[0033]

[Table 2]

The oxygen indexes of Examples 1 to 9 were in the range of 33 to 42, all of which were high values. In addition, it was confirmed that UL94 had excellent flame retardancy of V0 or more and excellent mechanical strength. In particular, in the formulations of Examples 7 to 9, the temperature reached 5 VA, and the burning time (total of n = 5) was 7 seconds or less, indicating extremely high flame retardancy and high mechanical strength. On the other hand, in the comparative example, a product satisfying both the flame retardancy and the mechanical strength was not obtained.

[0035]

The flame-retardant resin composition of the present invention does not use a halogen-based compound as a raw material, and therefore does not generate a halogen-based gas during combustion. Further, the flame-retardant resin composition of the present invention has both excellent flame retardancy and mechanical strength due to the synergistic effect of (B) and (C). It can be used in fields requiring properties, for example, flame-retardant electric wires, flame-retardant tapes, flame-retardant tubes, automotive interior materials, films for building materials, electric parts and the like.

Claims (6)

[Claims] 1. A thermoplastic resin (A) having the following general formula (I)
A flame-retardant resin composition comprising a magnesium hydroxide-based solid solution (B) as shown in (1) and a salt of an inorganic acid and melamine (C). Mg _1-x M _x (OH) ₂ ... (I) (wherein, M represents at least one divalent metal ion selected from the group consisting of Mn, Fe, Co, Ni, Cu, and Zn; Is 0.001 ≦ x <0.5.) 2. A blend of 80 to 200 parts by weight of a magnesium hydroxide-based solid solution (B) and 3 to 30 parts by weight of a salt of an inorganic acid and melamine (C) with respect to 100 parts by weight of a thermoplastic resin (A). The flame-retardant resin composition according to claim 1, wherein: 3. The thermoplastic resin (A) comprises an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer,
One or more selected from ethylene-methyl methacrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, and linear low-density polyethylene, or a mixture of two or more thereof. The flame-retardant resin composition according to claim 1 or 2, wherein 4. A method according to claim 1, wherein (A) is an ethylene-vinyl acetate copolymer (a1) and an ethylene-methyl methacrylate copolymer (a).
2) At least the mixture of a)
The flame-retardant resin composition according to any one of claims 1 to 3, wherein 2 is 0.1 to 1.5. 5. The flame-retardant resin composition according to claim 1, wherein (C) is melamine sulfate. 6. A molded article obtained by using the flame-retardant resin composition according to any one of claims 1 to 5.