JP2585026B2 - Inorganic flame retardant for thermoplastic resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnesium hydroxide type inorganic flame retardant for a thermoplastic resin having excellent carbonation resistance.

[Conventional technology]

Recently, magnesium hydroxide has attracted attention as a harmless flame retardant for thermoplastic resins, and various proposals have been made regarding thermoplastic resin flame retardants using the same magnesium hydroxide.

For example, JP-A-51-82334 discloses a self-extinguishing resin composition containing 55 to 25% by weight of a thermoplastic resin having a melt index of 10 to 0.1 g / 10 minutes and 45 to 75% by weight of magnesium hydroxide. It has been proposed to use magnesium hydroxide having a specific surface area of 45 m ² / g or less in order to prevent the generation of silver streaks in extrusion or injection molding.

JP-A-52-59643 discloses that the bulk density of a magnesium hydroxide powder is 0.35 to 0.70 g / m in order to improve uniform dispersibility in a resin, moldability or mechanical properties of the resin.
A plastic filler having a specific surface area of 10 to 30 m ² / g in cc, and a ratio of a thickness of a crystallite in a direction perpendicular to a (110) plane in a crystal lattice to that of a (001) plane of 1.7 to 2.7 is used. Proposals have been made to use it.

Furthermore, Japanese Patent Publication No. 52-43663 discloses an average particle size for improving the moldability, mechanical properties, and heat deterioration properties of a resin.
It has been proposed to use magnesium hydroxide having an oil absorption of 50 ml / g or less and an activity value of 30 mg / g or less in an amount of 40% by weight or more based on the thermoplastic resin.

Further, Japanese Patent Application Laid-Open No. 54-83952 discloses various properties such as dispersibility, non-agglomeration, suitability for molding, imparting physical properties such as impact resistance, improving molding appearance, and flame retardancy to resin. The BET specific surface area is about 20 m ² / g or less and the ratio of the BET specific surface area / Brain method specific surface area is 1 to about 3
It has been proposed to use magnesium hydroxide in the range of (1).

[Problems to be solved by the invention]

Recently, regarding a thermoplastic resin composition using magnesium hydroxide as a flame retardant, there has been a problem of deterioration of the resin due to carbonation of magnesium hydroxide. Magnesium hydroxide originally has high reactivity with carbon dioxide, and gradually reacts with dilute carbon dioxide to produce magnesium carbonate. In other words, magnesium hydroxide filled in the resin as a flame retardant reacts slowly with carbon dioxide in the air,
Magnesium carbonate (xMgCO ₃ · yMg
(OH) ₂ · zH ₂ O) crystals precipitate. As a result, the surface of the resin composition is powdered, the appearance is deteriorated, and the physical properties of the resin such as strength and insulating properties are remarkably reduced, so that the resin composition cannot be used.

Conventionally, various proposals have been made for the purpose of improving the properties of a resin composition by limiting the properties of magnesium hydroxide used in a thermoplastic resin as a flame retardant as described above. In any case, the problem of deterioration of the resin composition due to carbonation of magnesium is powerless.

In addition, magnesium hydroxide used as a flame retardant is usually surface-modified with an anionic surfactant or the like in order to improve compatibility with a resin. When used for a resin, deterioration of the resin due to carbonation of magnesium hydroxide cannot be prevented. Furthermore, in the step of kneading magnesium hydroxide in the resin, a method of using an additive to prevent carbonation of magnesium hydroxide is considered, but it is difficult to perform uniform dispersion, It is difficult to completely prevent deterioration of the resin composition due to carbonation.

Further, in order to improve the carbonation resistance of magnesium hydroxide, JP-A-52-128899 discloses that magnesium hydroxide is dissolved in a solution having amphoteric hydroxide in water of pH ≧ 3. JP-A-52-65538 discloses a method of treating magnesium hydroxide with P-nitrobenzeneazoorcinol, and JP-A-52-65539 discloses a method of treating magnesium hydroxide with P-nitrobenzeneazo-α-naphthol. A method of treating magnesium hydroxide has been proposed,
All were aimed at mild carbon oxide resistance, and could not exhibit sufficient carbonation resistance under severe carbonation conditions.

An object of the present invention is to solve the above problems and to provide an inorganic flame retardant for a heat-superplastic resin excellent in carbonation resistance.

[Means for Solving the Problems] [Action] As a result of repeated studies to solve the problems as described above, the present inventors produced a magnesium-antimony compound on the surface of magnesium hydroxide particles, It has been discovered that the carbonation resistance can be significantly improved by making the particles.

That is, the present invention comprises composite particles in which magnesium hydroxide particles are reacted with antimony chloride using water as a medium and the surface portion of the magnesium hydroxide particles is a magnesium-antimony compound, and the magnesium-antimony compound in the composite particles is It is a carbonation-resistant inorganic flame retardant for thermoplastic resin, characterized in that its content is 2 to 30% by weight.

Magnesium hydroxide used as a raw material in the present invention,
Ordinary products obtained by known production methods may be used. For example,
A method of obtaining magnesium hydroxide by adding an alkaline substance such as slaked lime to seawater or bitterness,
As disclosed in JP-A-115799, a method for obtaining magnesium hydroxide by heating a basic magnesium chloride or nitrate-magnesium salt in an aqueous medium under a pressurized condition.
As disclosed in Japanese Patent No. 109820, a method of obtaining magnesium hydroxide by hydrating magnesium oxide calcined at 1400 ° C. or higher in an aqueous suspension slurry of an acid or a magnesium salt, and further disclosed in JP-A-60-15529 As shown, a method may be mentioned in which ammonia gas is blown into synthetic bitter to cause a reaction to obtain magnesium hydroxide. The specific surface area or particle diameter of the magnesium hydroxide used as a raw material is not particularly limited, but is preferably selected in consideration of the mechanical substance of the obtained resin.

In order to generate a magnesium-antimony compound on the surface of the magnesium hydroxide particles, magnesium hydroxide and antimony chloride are reacted in an aqueous solution. SbCl ₃ and SbCl ₅ can be used as antimony chloride. By this reaction, magnesium-antimony compounds such as Mg ₄ Sb ₂ O ₉ , MgSb ₂ O ₆ , Mg ₂ Sb ₂ O ₇ , and MgSb ₂ O ₄ are formed on the surface of the magnesium hydroxide particles.

The mechanism by which the magnesium-antimony compound is formed on the surface of the magnesium hydroxide particles is not clear, but, for example, when SbCl ₃ is added to an aqueous suspension of magnesium hydroxide, SbCl ₃ is added and hydrolyzed in the slurry. Then, it can be inferred that SbOCl reacts with magnesium hydroxide on the particle surface to generate a magnesium-antimony compound.

As can be seen in JP-A-53-30648 and JP-A-62-41242, the flame retardant effect was improved by adding antimony oxide (for example, Sb ₂ O ₃ ) to magnesium hydroxide. Although inorganic flame retardants have been proposed, they cannot be used in the present invention because antimony oxide is almost insoluble in water.

The content of the magnesium-antimony compound in the composite particles needs to be 2 to 30% by weight, and if the content is less than 2% by weight, the carbonation resistance of the composite particles is not sufficient, and 30% by weight.
%, The effect as a flame retardant becomes insufficient, which is not preferable. On the other hand, if the content exceeds 15% by weight, the carbonation resistance is not improved in spite of the cost increase, so that the content of the magnesium-antimony compound must be selected as needed within the above range.

The mechanism by which the carbonation resistance is improved in the present invention is considered to be due to the fact that the magnesium-antimony compound inert to carbon dioxide is formed almost uniformly on the surface of the magnesium hydroxide to form composite particles.

Although the composite particles in the present invention can be used as they are as a flame retardant, they may be used after further modifying the surface with an organic substance in order to improve the compatibility with the resin. Organic substances used for surface modification include anionic surfactants such as sodium stearate, potassium stearate, sodium oleate, potassium oleate, sodium laurate, potassium laurate, sodium behenate, potassium behenate, lauryl. Examples thereof include sodium benzenesulfonate and coupling agents such as vinyltriethoxysilane, γ-glucidoxypropyltrimethoxysilane, isopropyltriisostearoyl titanate, and bisdioctylhyrophosphate oxyacetate titanate.

〔The invention's effect〕

As described above, by using the composite according to the present invention as a flame retardant for a thermoplastic resin, a magnesium hydroxide type excellent in carbonation resistance, which cannot be achieved by a conventional flame retardant using magnesium hydroxide, is obtained. A flammable resin can be manufactured, and the effect is great.

〔Example〕

 Hereinafter, the present invention will be described specifically with reference to Examples.

Example 1 1 kg of magnesium hydroxide having a BET specific surface area of about 10 m ² / g
Was suspended in water, and 400 g of SbCl ₃ was added to the suspension slurry. After stirring for 1 hour, dehydration, washing with water, and dry pulverization were performed. Observation of the obtained powder by X-ray diffraction revealed that the powder had a composition of magnesium hydroxide and MgSb ₂ O ₆ . According to the analysis result, MgSb ₂ O ₆ in the powder was about 20 wt%. When this powder was observed with a TEM, it was found that the particles were almost the same as the magnesium hydroxide used, and had extremely fine particles formed on the surface. The obtained powder was mixed with 150 parts with respect to 100 parts of EVA resin, and roll-molded. Using the molded sheet, a carbonation resistance test and a flammability test were performed.
Table 1 shows the results.

Examples 2 to 6 and Comparative Examples 1 to 3 Powders were prepared in the same manner as in Example 1, except that the amount of SbCl ₃ added was changed, and mixed with EVA resin to perform the same test. Table 1 shows the results.

Example 7 and Comparative Example 4 The powders obtained in Example 3 and Comparative Example 1 were surface-modified with stearic acid, and the same test as in Example 1 was performed.
Table 1 shows the results.

Comparative Example 5 A powder was obtained under the same conditions as in Example 1 except that 400 g of SbCl _{3 in} Example 1 was changed to 200 g of Sb ₂ O ₃ . Observation of the obtained powder by X-ray diffraction revealed that the powder was composed of magnesium hydroxide and Sb ₂ O _3, and from the analysis results, it was found that Sb ₂ O ₃ in the powder was about 17 wt%. In addition, this powder
Observation by EM showed that magnesium hydroxide particles and Sb ₂ O
It was a mixture with ₃ particles. The obtained powder is EVA resin 100
The same test as in Example 1 was carried out using a molded sheet obtained by mixing 150 parts by weight and roll forming. Table 1 shows the results.

Continuation of the front page (56) References JP-A-53-30648 (JP, A) JP-A-62-41242 (JP, A)

Claims (1)

(57) [Claims] 1. A composite particle comprising a magnesium-antimony compound in which the surface of the magnesium hydroxide particle is reacted with antimony chloride using water as a medium, wherein the magnesium-antimony compound is contained in the composite particle. A carbonation-resistant inorganic flame retardant for a thermoplastic resin, wherein the content is 2 to 30% by weight.