JP2003253266A - Flame-retardant, method for production thereof and flame-retardant resin composition containing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant composed mainly of magnesium hydroxide particles and having excellent acid resistance. <P>SOLUTION: The flame retardant is composed of magnesium hydroxide particles having a surface-coating layer composed of 0.1-20 wt.% silica in terms of SiO<SB>2</SB>based on the magnesium hydroxide. Preferably, the magnesium hydroxide particle is further surface-treated with at least one kind of surface-treating agent selected from higher fatty acids, higher fatty acid alkali metal salts, polyhydric alcohol higher fatty acid esters, anionic surfactants, phosphoric acid esters, silane coupling agents, aluminum coupling agents, titanate coupling agents, organosilanes, organosiloxanes and organosilazanes. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a flame retardant mainly containing magnesium hydroxide particles, a method for producing the same, and a flame retardant resin composition containing the same. More specifically, the present invention relates to a flame retardant composed of magnesium hydroxide particles having a coating layer composed of silica on the surface thereof, and preferably, it is difficult to further treat such magnesium hydroxide particles with a surface treating agent. Regarding fuel. When such a flame retardant according to the present invention is blended with a resin to form a flame-retardant resin composition, the resin composition can have excellent acid resistance. Furthermore, the present invention relates to a method for producing such a flame retardant and a flame retardant resin composition containing the same.

[0002]

2. Description of the Related Art Conventionally, thermoplastic resins are widely used in various industrial fields such as construction, electricity, machinery, transportation, etc. because they are excellent in moldability and mechanical properties and electrical properties. Has been. In particular, a polyvinyl chloride resin composition containing a halogen-based flame retardant has excellent flame retardancy and is therefore widely used as a wire coating. However, such a wire coating causes a situation of burning once. In that case, a toxic halogen gas is generated, and if such a situation occurs in an underground facility or the like, for example, a serious situation may occur.

Therefore, in recent years, in order to solve such a problem, it has been recommended to use a polyolefin resin as a resin and a non-halogen flame retardant such as magnesium hydroxide as a flame retardant.

It is well known in the art that metal hydroxides such as magnesium hydroxide are useful as flame retardants. However, in general, a metal hydroxide must be blended in a large amount with respect to the resin in order to impart effective flame retardancy to the resin composition, while the metal hydroxide is a hydrophilic compound having a hydroxyl group. There is a problem that the dispersibility is poor because the dispersibility and compatibility with the resin, which is an inorganic substance and an organic polymer, is low. In addition, when a large amount of metal hydroxide is mixed with a resin to form a flame-retardant resin composition, the desired physical properties of the resin may be impaired. Further, in general, metal hydroxides are likely to react with acids, and for example, a resin composition containing a large amount of magnesium hydroxide will give rise to carbonates or carbonates due to the action of moisture or carbon dioxide in the air over time. There is a problem that a basic carbonate is generated to cause a whitening phenomenon in which the surface of the resin composition becomes white.

Therefore, in order to solve the above-mentioned problems of the flame retardant composed mainly of magnesium hydroxide, various improvements have been conventionally proposed. For example, Japanese Unexamined Patent Publication No. 1-24503
Japanese Patent Laid-Open Publication No. 9-93 proposes that a magnesium hydroxide particle surface has a coating layer composed of a higher fatty acid alkali metal salt and a water-insoluble salt of boric acid or silicic acid to improve acid resistance and dispersibility. There is. Similarly, JP-A-10-3388.
Japanese Patent Laid-Open No. 18 proposes to provide a coating layer made of aluminum hydroxide on the surface of magnesium hydroxide particles in order to enhance acid resistance.

As described above, conventionally, a coating layer is formed on the surface of magnesium hydroxide particles to improve the performance as a flame retardant, and the dispersibility and the dispersibility when the resin composition is blended with a resin. Various attempts have been made to improve the acid resistance, but the improvement of the acid resistance is still insufficient. Therefore, conventionally, the flame retardant mainly composed of magnesium hydroxide particles has been used as an acid chemical or an acid gas. It could not be used for chemical plant applications that often come into contact with or for outdoor applications that are exposed to acid rain. In addition, it cannot be used for applications such as lithography resists that are subjected to acid cleaning.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems in the conventional flame retardant composed of magnesium hydroxide. The purpose is to provide an excellent flame retardant. A further object of the present invention is to provide a method for producing such a flame retardant and a flame retardant resin composition containing the same.

[0008]

According to the present invention, it is difficult to form magnesium hydroxide particles having a coating layer of 0.1 to 20% by weight of SiO ₂ on the surface of magnesium hydroxide in terms of SiO _{2 with} respect to magnesium hydroxide. A combustible is provided.

Further, according to the present invention, magnesium hydroxide particles having a coating layer composed of 0.1 to 20% by weight of silica in terms of SiO _{2 with} respect to magnesium hydroxide on the surface are used as the higher fatty acid or higher fatty acid alkali. At least one selected from metal salts, polyhydric alcohol higher fatty acid esters, anionic surfactants, phosphoric acid esters, silane coupling agents, aluminum coupling agents, titanate coupling agents, organosilanes, organosiloxanes and organosilazanes. Provided is a flame retardant obtained by surface treatment with a surface treatment agent.

Further, according to the present invention, after coating the surface of the magnesium hydroxide particles with a coating layer made of silica in an amount of 0.1 to 20% by weight in terms of SiO _{2 with} respect to magnesium hydroxide, further, Higher fatty acid, higher fatty acid alkali metal salt, polyhydric alcohol higher fatty acid ester, anionic surfactant, phosphoric acid ester, silane coupling agent,
Provided is a method for producing a flame retardant, which comprises performing surface treatment with at least one surface treatment agent selected from aluminum coupling agents, titanate coupling agents, organosilanes, organosiloxanes and organosilazanes.

Further, according to the present invention, there is provided a flame-retardant resin composition obtained by mixing 5 to 350 parts by weight of the flame retardant with 100 parts by weight of the resin.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, silica, alumina, titania and zirconia are each SiO ₂ .n.
H ₂ O (0 ≦ n ≦ 2), Al ₂ O ₃ · nH ₂ O (0 ≦ n ≦
3), TiO ₂ · nH ₂ O (0 ≦ n ≦ 2) and ZrO ₂ ·
It means a (hydrous) oxide of silicon, aluminum, titanium and zirconium represented by nH ₂ O (0 ≦ n ≦ 2).

The flame retardant according to the present invention comprises magnesium hydroxide particles having on the surface thereof a coating layer of 0.1 to 20% by weight of silica in terms of SiO _{2 with} respect to magnesium hydroxide.

According to the invention, the water-soluble silicate is neutralized with an acid in the presence of magnesium hydroxide particles at a temperature in the range 5 to 100 ° C., preferably in the range 50 to 95 ° C. By depositing silica on the surface of the magnesium hydroxide particles, a coating layer made of silica can be provided on the surface of the magnesium hydroxide particles.

In particular, according to the invention, an aqueous slurry of magnesium hydroxide particles is above 60 ° C., preferably 60
While maintaining at ~ 95 ° C, 0.1 to 20% by weight of water-soluble silicate (e.g., sodium silicate) in terms of SiO _{2 with} respect to magnesium hydroxide was added to the resulting mixture. Acid (for example, sulfuric acid or hydrochloric acid) is added over 40 minutes, and the slurry is adjusted to pH 6 to 10, preferably
It is preferable that the surface of the magnesium hydroxide particles is provided with a coating layer made of dense and high-density silica by neutralizing to 6 to 9.5.

In this method, a water-soluble silicate was added to an aqueous slurry of magnesium hydroxide particles when a coating layer made of dense and high-density silica was formed on the surface of the magnesium hydroxide particles. The upper limit of the time to add the acid to the mixture is not particularly limited, however,
From the viewpoint of production efficiency, it is usually about 3 hours.

A coating layer made of such high-density silica
Magnesium hydroxide particles having
An aqueous slurry of magnesium hydroxide particles at 60 ° C or higher,
Hydroxylation is preferably performed while maintaining the temperature at 60 to 95 ° C.
SiO for magnesium ₂0.1 to 20 layers in conversion
% Water soluble silicate (eg sodium silicate)
And acid (for example, sulfuric acid or hydrochloric acid) in an approximately equivalent ratio for 40 minutes
After adding over the above, if necessary, add more acid,
Neutralize to pH 6-10, preferably 6-9.5
The same can be obtained by and.

Also in this method, the upper limit of the time for adding the silicate and the acid to the slurry of the magnesium hydroxide particles when the coating layer made of dense and high-density silica is formed on the surface of the magnesium hydroxide particles. Although not particularly limited, it is usually about 3 hours from the viewpoint of production efficiency.

In the above two methods of forming a coating layer made of silica on the surface of magnesium hydroxide particles,
When a water-soluble silicate is added to an aqueous slurry of magnesium hydroxide particles and an acid is added to the obtained mixture in a short time such as 10 minutes, or an aqueous slurry of magnesium hydroxide particles. When a water-soluble silicate and an acid are added in a short time, the coating layer made of silica formed on the surface of the magnesium hydroxide particles is not dense and has a low density. However, the flame retardant according to the present invention may have a coating layer made of low-density silica on the surface of the magnesium hydroxide particles as described above.

However, according to the present invention, as described above, when a coating layer made of low-density silica is formed by forming a coating layer made of high-density silica on the surface of magnesium hydroxide particles. In comparison, a flame retardant with improved acid resistance can be obtained.

According to the present invention, as described above, when a flame retardant composed of magnesium hydroxide particles having a coating layer composed of silica on the surface thereof is obtained, the water-soluble silicate is added to magnesium hydroxide. In terms of SiO ₂ ,
It is preferably used in the range of 1 to 20% by weight, and most preferably in the range of 3 to 20% by weight.

In the present invention, the magnesium hydroxide slurry is a magnesium hydroxide prepared by neutralizing an aqueous solution of a water-soluble magnesium salt (eg, magnesium chloride or magnesium nitrate) with an alkali such as sodium hydroxide or ammonia. It refers to an aqueous slurry obtained by precipitation or an aqueous slurry obtained by dispersing magnesium hydroxide particles in an aqueous medium.

The origin of the above-mentioned magnesium hydroxide particles is not limited at all, and for example, it is obtained by pulverizing natural ore or an aqueous solution of magnesium salt to be neutralized with an alkali. It may be a powder, a powder obtained by treating magnesium hydroxide particles with an appropriate modifier such as a borate salt, a phosphate salt, a water-soluble zinc salt, or the like. Further, the magnesium hydroxide particles may be a solid solution containing different metal elements such as zinc, cobalt, copper, nickel and iron.

In the present invention, the aqueous slurry means an aqueous solution in which the dispersion medium of the slurry contains water or a small amount of a water-soluble organic solvent. Similarly, the aqueous solution means that the solvent of the solution is water or a small amount of a water-soluble organic solvent. An aqueous solution containing an organic solvent.

According to the present invention, the flame retardant of magnesium hydroxide particles having a coating layer of silica on the surface, the coating layer made of silica per magnesium hydroxide, in terms of SiO _2, 0. 1 to 20% by weight, preferably 1 to 20% by weight,
Particularly preferably, it is in the range of 3 to 20% by weight. The ratio of the coating layer made of silica is magnesium hydroxide,
When it is less than 0.1% by weight in terms of SiO ₂ ,
When a flame retardant having excellent acid resistance cannot be obtained, and the ratio of the coating layer made of silica is more than 20% by weight in terms of SiO _{2 with} respect to magnesium hydroxide,
The flame retardance per unit weight of the flame retardant becomes low, and in order to impart the desired flame retardancy to the resin composition, it is necessary to blend an unnecessarily large amount of the flame retardant, and the desired properties of the resin are required. There is a risk of damage.

As described above, after adding the water-soluble silicate to the magnesium hydroxide slurry, an acid (for example, sulfuric acid) is added to neutralize the silicate, or the water-soluble silicate is added to the slurry. By simultaneously adding an acid salt and an acid to neutralize the silicate, silica is precipitated on the surface of the magnesium hydroxide particles, thus forming a coating layer made of silica on the surface of the magnesium hydroxide particles. be able to. However, the magnesium hydroxide slurry having the silica coating layer formed in this manner has a disadvantage of poor filterability.

Therefore, according to the present invention, as described above, after forming a coating layer made of silica on the surface of the magnesium hydroxide particles in the slurry of magnesium hydroxide, the coating layer is similarly formed on the coating layer. By further forming a second coating layer made of at least one selected from alumina, titania and zirconia, the filterability of the magnesium hydroxide particles can be improved. here,
The proportion of the second coating layer is appropriately in the range of 0.03 to 10% by weight in total calculated as Al ₂ O ₃ , TiO ₂ and ZrO _{2 with} respect to magnesium hydroxide. Is. In the present invention, the coating layer made of silica on the surface of the magnesium hydroxide particles may be referred to as the first coating layer with respect to the second coating layer.

To form a coating layer made of alumina as the second coating layer, as described above, the water-soluble silicate is added to the slurry of magnesium hydroxide, and then the acid is added to the above-mentioned silicate. Or a water-soluble silicate and an acid are added to the slurry at the same time to neutralize the silicate to precipitate silica on the surface of the magnesium hydroxide particles, and thus silica on the surface. After obtaining a slurry of magnesium hydroxide particles having a coating layer made of, while maintaining the pH constant, sodium aluminate and an acid (for example, sulfuric acid or hydrochloric acid) may be added to the slurry for aging.

Similarly, to form a coating layer made of titania as the second coating layer, after forming a coating layer made of silica on the surface of magnesium hydroxide particles in a slurry of magnesium hydroxide, the slurry is made For example, add titanyl sulfate and alkali (eg sodium hydroxide),
It may be aged, and in order to form a coating layer made of zirconia as the second coating layer, a coating layer made of silica is formed on the surface of magnesium hydroxide particles in a slurry of magnesium hydroxide, and then the slurry is added to the slurry. For example, zirconyl sulfate and alkali (for example, sodium hydroxide) may be added and aged.

However, according to the present invention, as described above, a coating layer made of silica is formed on the surface of the magnesium hydroxide particles, and then a second coating layer made of alumina, titania or zirconia is formed thereon. Instead of forming, a coating layer containing, on the surface of the magnesium hydroxide particles, a second oxide consisting of at least one selected from alumina, titania and zirconia together with silica is similarly formed. The filterability of magnesium oxide particles can be improved.

As described above, even when a coating layer made of silica and at least one second oxide selected from alumina, titania and zirconia is formed on the surface of the magnesium hydroxide particles, the ratio of silica is water. It is in the range of 0.1 to 20 wt% in terms of SiO _{2 with} respect to magnesium oxide, and the proportion of the second oxide is in terms of Al ₂ O ₃ , TiO ₂ and ZrO _{2 with} respect to magnesium hydroxide. In total, the range is 0.03 to 10% by weight.

To form a coating layer made of silica and alumina on the surface of magnesium hydroxide particles, for example, a water-soluble silicate and sodium aluminate are added to a slurry of magnesium hydroxide, and then an acid is added. The silicate and sodium aluminate are neutralized, or the water-soluble silicate, sodium aluminate and acid are simultaneously added to the slurry to neutralize the silicate and sodium aluminate. The silica and alumina may be deposited on the surface of the magnesium hydroxide particles.

The preferred flame retardant according to the present invention is magnesium hydroxide particles having a coating layer consisting of 0.1 to 20% by weight of silica in terms of SiO _{2 with} respect to magnesium hydroxide on the surface of higher hydroxide or higher fatty acid alkali. Metal salt,
At least one surface treatment agent selected from polyhydric alcohol higher fatty acid ester, anionic surfactant, phosphoric acid ester, silane coupling agent, aluminum coupling agent, titanate coupling agent, organosilane, organosiloxane and organosilazane The surface treatment is performed at.

Such a flame retardant according to the present invention comprises a magnesium hydroxide particle having a surface coated with a coating layer made of silica in an amount of 0.1 to 20% by weight based on SiO _{2 of} magnesium hydroxide. Furthermore, higher fatty acids, higher fatty acid alkali metal salts, polyhydric alcohol higher fatty acid esters,
Obtained by surface treatment with at least one surface treatment agent selected from anionic surfactants, phosphoric acid esters, silane coupling agents, aluminum coupling agents, titanate coupling agents, organosilanes, organosiloxanes and organosilazanes be able to.

Surface treatment of the magnesium hydroxide particles with the above-mentioned surface treatment agent hardly improves the acid resistance thereof.
However, according to the present invention, first, a coating layer made of silica is provided on the surface, and then such a magnesium hydroxide particle is subjected to a surface treatment with a surface treating agent, whereby the acid resistance is remarkably improved. A flame retardant composed of magnesium particles can be obtained.

According to the present invention, when a flame retardant obtained by further surface-treating magnesium hydroxide particles having a coating layer made of silica with a surface-treating agent is obtained, the surface of the magnesium hydroxide particles is In order to impart a coating made of silica to the water-soluble silicate, the content of the water-soluble silicate is 0.1 to 20% by weight in terms of SiO _{2 with} respect to magnesium hydroxide,
It is preferably used in the range of 0.5 to 15% by weight.

When a coating layer made of silica is formed on the surface of magnesium hydroxide particles by using less than 0.1% by weight of water-soluble silicate in terms of SiO _{2 with} respect to magnesium hydroxide. Even if such magnesium hydroxide particles are further treated with a surface treatment agent, a flame retardant having excellent acid resistance cannot be obtained. On the other hand, when the ratio of the coating layer made of silica is magnesium hydroxide to SiO ₂
When it is more than 20% by weight in terms of conversion, the flame retardancy per unit weight of the flame retardant becomes low, and an unnecessarily large amount of flame retardant is added to impart desired flame retardancy to the resin composition. There is no choice but to mix them, which may impair the desired properties of the resin.

According to the present invention, the surface of the magnesium hydroxide particles is thus provided with a coating layer made of silica, or the first coating layer made of silica and at least one selected from alumina, titania and zirconia. A second coating layer made of a seed, or after forming a coating layer made of silica and at least one selected from alumina, titania and zirconia, and further subjecting this to a surface treatment agent for surface treatment. The acid resistance can be dramatically increased by the synergistic effect of the coating layer made of silica and the surface treatment with the surface treatment agent.

According to the present invention, the above-mentioned surface treatment agent is preferably higher fatty acid, higher fatty acid alkali metal salt, polyhydric alcohol higher fatty acid ester, anionic surfactant, phosphoric acid ester, silane coupling agent, At least one selected from aluminum coupling agents, titanate coupling agents, organosilanes, organosiloxanes and organosilazanes is used.

The higher fatty acid is preferably a saturated or unsaturated higher fatty acid having 14 to 24 carbon atoms,
Specific examples thereof include oleic acid and stearic acid. Further, as the alkali metal salt of such higher fatty acid, for example, sodium salt and potassium salt are preferable. Specific examples of the polyhydric alcohol fatty acid ester include glycerin monostearate and glycerin monooleate.

Examples of the anionic surfactants include sulfuric acid ester salts of higher alcohols such as stearyl alcohol and oleyl alcohol, sulfuric acid ester salts of polyethylene glycol ether, amide bond sulfuric acid ester salts, ester bond sulfuric acid ester salts, ester bond. Examples thereof include sulfonate, amide bond sulfonate, ether bond sulfonate, ether bond alkylallyl sulfonate, ester bond alkylallyl sulfonate, and amide bond alkylallyl sulfonate.

As the phosphoric acid ester, phosphoric acid triester, diester, monoester or a mixture thereof is used. As a specific example of phosphoric acid triester,
For example, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, hydroxylphenyl diphenyl phosphate, cresyl diphenyl phosphate. , Xylenyl diphenyl phosphate, oleyl phosphate, stearyl phosphate and the like.

Specific examples of the diester or monoester (that is, acidic phosphate ester) include, for example, methyl acid phosphate (mixture of monomethyl ester and dimethyl ester), ethyl acid phosphate (monoethyl ester and diethyl ester). Mixture), isopropyl acid phosphate (mixture of monoisopropyl ester and diisopropyl ester), butyl acid phosphate (mixture of monobutyl ester and dibutyl ester), 2-ethylhexyl acid phosphate (mono-2-ethylhexyl ester and di-2- Mixture with ethylhexyl ester), isodecyl acid phosphate (mixture of monoisodecyl ester and diisodecyl ester), dilauryl acid phosphate, Uryl acid phosphate (mixture of monolauryl ester and dilauryl ester), tridecyl acid phosphate (mixture of monotridecyl acid phosphate and ditridecyl acid phosphate), monostearyl acid phosphate, distearyl acid phosphate, stearyl acid phosphate ( Mixture of monostearyl ester and distearyl ester), isostearyl acid phosphate (mixture of monoisostearyl ester and diisostearyl ester), oleyl acid phosphate (mixture of monooleyl ester and dioleyl ester), behenyl acid phosphate (A mixture of monobehenyl ester and dibehenyl ester) and the like.

These acidic phosphoric acid esters may be metal salts, that is, salts of at least one metal selected from Ia, IIa, IIb and IIIa of the periodic table. Therefore,
Preferred specific examples include, for example, lithium salt, magnesium salt, calcium salt, strontium salt, barium salt, zinc salt, aluminum salt and the like.

The silane coupling agent is a hydrolyzable group typified by an alkoxyl group together with a reactive functional group selected from an amino group, an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, a mercapto group, a chlorine atom and the like. With organosilane.

Therefore, the silane coupling agent is not particularly limited, but for example, vinylethoxysilane, vinyltris (2-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-amino. Propyltrimethoxysilane, β-
(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, 3-
Examples include chloropropyltrimethoxysilane and the like.

Examples of the aluminum coupling agent include acetylalkoxyaluminum diisopropylate, and examples of the titanate coupling agent include isopropyl triisostearoyl titanate and isopropyl tris (dioctyl pyrophosphate) titanate. , Isopropyl tri (N
-Aminoethylaminoethyl) titanate, isopropyl tridecylbenzene sulfonyl titanate and the like can be exemplified.

As the organosiloxane, an organosiloxane oligomer containing an organodisiloxane or an organopolysiloxane is used. Examples of the organodisiloxane include hexamethyldisiloxane, hexaethyldisiloxane, hexapropyldisiloxane,
Hexaphenyldisiloxane, sodium methylsiliconate and the like can be mentioned. Further, examples of the organosiloxane oligomer include methylphenylsiloxane oligomer and phenylsiloxane oligomer.

However, according to the present invention, organopolysiloxane is particularly preferable as the organosiloxane, and so-called silicone oil is particularly preferably used as a specific example of such organopolysiloxane. For example, so-called straight silicone oils such as dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, methylpolycyclosiloxane and the like can be mentioned.

According to the present invention, so-called modified silicone oils having various organic groups are also preferably used. Examples of such modified silicone oils include polyether modified, epoxy modified, amino modified, carboxyl modified, mercapto modified, carbinol modified, methacrylic modified, long chain alkyl modified silicone oils, etc. It is not limited to. The organosilane typically refers to an organosilicon compound having a hydrolyzable group such as an alkoxyl group together with an alkyl group and / or an aryl group.
Examples thereof include phenyltrimethoxysilane, diphenyldimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, trimethylchlorosilane, hexyltriethoxysilane and decyltrimethoxysilane.

Examples of the organosilazane include hexamethyldisilazane, hexaethyldisilazane, hexaphenyldisilazane, hexaethylcyclotrisilazane, methylpolysilazane, phenylpolysilazane and the like.

Such a surface treating agent is contained in an amount of 0.1 to 20% by weight, preferably 0.5 to 0.5%, based on magnesium hydroxide.
˜15% by weight, particularly preferably 1 to 10% by weight. The surface treatment of the magnesium hydroxide particles with such a surface treatment agent can be performed by either a wet method or a dry method. When the magnesium hydroxide particles are wet-treated, for example, as described above,
Form a coating of silica on the surface of the magnesium hydroxide particles in a magnesium hydroxide slurry, then
A surface treatment agent is added to the magnesium hydroxide slurry in an appropriate form such as an emulsion, an aqueous solution or a dispersion liquid,
PH 6-12 at a temperature of 20-95 ° C, preferably under heating.
After stirring and mixing in the above range, the magnesium hydroxide particles may be filtered, washed with water, dried and pulverized.

When the surface treatment of the magnesium hydroxide particles is carried out by a dry method, as described above, after the silica coating is formed on the surface of the magnesium hydroxide particles in the slurry of magnesium hydroxide, a water treatment is conducted. The magnesium oxide particles are filtered, washed with water, dried and crushed.
The surface treatment agent may be stirred and mixed at 00 ° C., preferably under heating.

The flame retardant according to the present invention thus comprises magnesium hydroxide particles having a coating layer made of silica on the surface, and preferably such magnesium hydroxide particles are further surface-treated with the above-mentioned surface treating agent. It has a high acid resistance. In particular, according to the present invention, a flame retardant having excellent acid resistance can be obtained by using an organosiloxane, a silane coupling agent or an organosilane as the surface treatment agent. In the present invention, the most preferable surface treatment agent is an organopolysiloxane, and by using methylhydrogenpolysiloxane among the organopolysiloxanes, a flame retardant having a remarkably high acid resistance can be obtained.

The flame-retardant resin composition according to the present invention can be obtained by uniformly blending the above-mentioned flame retardant with the resin. The mixing ratio of the flame retardant to the resin depends on the use and required characteristics of the resulting resin composition, but is usually 100
It can be obtained by blending 5 to 350 parts by weight of the flame retardant with respect to parts by weight.

For example, resin 100 is used to prepare a flame-retardant resin composition for use as a flooring material, a wallpaper, a building material such as a decorative board, a casing of an electric device or a general molded product such as a transparent film.
A resin composition obtained by blending 5 to 200 parts by weight of the flame retardant according to the present invention with respect to parts by weight is preferably used. On the other hand, in order to obtain a self-extinguishing resin composition such as a wire or cable coating, the flame retardant according to the present invention is usually 50 to 350 parts by weight, preferably 10 parts by weight, based on 100 parts by weight of the resin.
A resin composition containing 0 to 300 parts by weight is preferably used. Further, for example, in the case of a resist for lithography, it is usually preferable to add 80 to 150 parts by weight of the flame retardant of the present invention to 100 parts by weight of the solid content. The amount of the flame retardant compounded to 100 parts by weight of the resin is 350
When it exceeds the weight part, desirable mechanical properties and chemical properties of the resin composition may be deteriorated.

In the present invention, the above resin may be appropriately selected according to the intended use and the required characteristics. Specific examples include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene monomer ternary copolymer. Polymer, ethylene-butene copolymer, ethylene-
Acrylic ester (for example, ethyl acrylate) copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer or other olefin homo- or copolymer polyolefin resin, aromatic such as styrene Homopolymer of vinyl monomer, copolymer such as ABS resin, poly (meth) acrylic resin, polyester such as polyethylene terephthalate, polybutylene terephthalate and polyarylate, 6-nylon, 6,6-nylon, 12- Polyamide such as nylon, 46-nylon, aromatic polyamide, polyphenylene ether, modified polyphenylene ether, polyether such as polyoxymethylene, polycarbonate, styrene-conjugated diene copolymer, polybutadiene, polyisoprene, acrylonitrile-butadiene Copolymer elastomer polychloroprene, and polyvinyl chloride.

If necessary, a thermosetting resin such as phenol resin, epoxy resin, unsaturated polyester or polyurethane may be used as the resin. These resins are used alone or as a mixture of two or more kinds.

The flame-retardant resin composition according to the present invention may contain, in addition to the above-mentioned flame-retardant agent, other additives, if necessary, depending on the respective resins. As such an additive, for example, a plasticizer, a lubricant, a filler, an antioxidant, a heat stabilizer, a nucleating agent, a cross-linking agent, a cross-linking aid, an antistatic agent, a compatibilizer, a light-proofing agent, a pigment, A foaming agent, an antifungal agent, etc. can be mentioned. Also, if necessary,
Other conventionally known flame retardants and flame retardant aids may be added.

Such a resin composition is kneaded by mixing the above flame retardant with the resin by an appropriate means such as a single-screw extruder, a twin-screw extruder, a roll kneader, a kneader kneader or a Banbury mixer. Can be obtained by Further, the resin composition according to the present invention thus obtained, depending on the application and purpose, for example, injection molding, extrusion molding, blow molding, press molding, vacuum molding, calender molding, transfer molding, laminate molding, It can be suitably used for the production of various molded products by appropriate means.

[0061]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples. (Preparation of flame retardant)

Example 1 (Preparation of flame retardant a) 4 mol / L in a reactor filled with 5 L of water
16.7 L of magnesium chloride aqueous solution and 14.3 mol /
After simultaneously adding 8.4 L of an aqueous sodium hydroxide solution of L under stirring, a hydrothermal reaction was carried out at 170 ° C. for 1 hour. The magnesium hydroxide thus obtained was filtered and washed with water, and the cake thus obtained was resuspended in water to obtain an aqueous slurry of magnesium hydroxide (150 g / L). Also in the following examples and comparative examples, a water slurry of magnesium hydroxide (150 g / L) was prepared in this manner.

The magnesium hydroxide slurry (15
20 g (0 g / L) was heated to 80 ° C., 150 g of sodium silicate as SiO ₂ was added, and sulfuric acid was added over 1 hour until the pH of the slurry reached 9, and the slurry was further added at 80 ° C. After aging for 1 hour, a coating layer made of high-density silica was formed on the surface of the magnesium hydroxide particles.
Magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried and pulverized to obtain a flame retardant a according to the present invention.

Example 2 (Preparation of flame retardant b) Magnesium hydroxide slurry (1
50 g / L) 20 L was heated to 80 ° C., 300 g of sodium silicate as SiO ₂ was added, and then the pH of the slurry
Sulfuric acid was added over 1 hour until the value reached 9, and the slurry was aged at 80 ° C. for 1 hour to form a coating layer made of high-density silica on the surface of the magnesium hydroxide particles. Magnesium hydroxide particles were separated from such slurry by filtration, washed with water, dried and pulverized to obtain a flame retardant b according to the present invention.

Example 3 (Preparation of flame retardant c) Magnesium hydroxide slurry (1
50 g / L) 20 L was heated to 80 ° C., 450 g of sodium silicate as SiO ₂ was added, and then the pH of the slurry
Sulfuric acid was added over 1 hour until the value reached 9, and the slurry was aged at 80 ° C. for 1 hour to form a coating layer made of high-density silica on the surface of the magnesium hydroxide particles. Magnesium hydroxide particles were separated from such a slurry by filtration, washed with water, dried and pulverized to obtain a flame retardant c according to the present invention.

Example 4 (Preparation of flame retardant d) Magnesium hydroxide slurry (1
50 g / L) 20 L was heated to 80 ° C., 450 g of sodium silicate as SiO ₂ was added, and then the pH of the slurry
Sulfuric acid was added over 10 minutes, and the slurry was aged at 80 ° C. for 1 hour to form a coating layer of low-density silica on the surface of the magnesium hydroxide particles. Magnesium hydroxide particles were separated from such a slurry by filtration, washed with water, dried and pulverized to obtain a flame retardant d according to the present invention.

Example 5 (Preparation of Flame Retardant A) 20 L of magnesium hydroxide aqueous slurry (150 g / L) was heated to 80 ° C. with stirring, and 30 g of sodium silicate in terms of SiO ₂ was added thereto. Then, sulfuric acid was added over 1 hour until the pH of the slurry reached 9, and the slurry was aged at 80 ° C. for 1 hour to form a coating layer made of high-density silica on the surface of the magnesium hydroxide particles. .

Next, a slurry of such magnesium hydroxide particles was added to methylhydrogenpolysiloxane 9
An emulsion containing 0 g was added, and the mixture was stirred at 80 ° C. for 1 hour, then magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried and pulverized to obtain a flame retardant A according to the present invention.
Got

Example 6 (Preparation of Flame Retardant B) In preparation of the above flame retardant A, except that 90 g of sodium silicate in terms of SiO ₂ was used.
Flame retardant B was obtained in the same manner.

Example 7 (Preparation of flame retardant C) Flame retardant C was obtained in the same manner as in the preparation of flame retardant A except that 150 g of sodium silicate was used in terms of SiO ₂ .

Example 8 (Preparation of Flame Retardant D) A flame retardant D was prepared in the same manner as above, except that 300 g of sodium silicate in terms of SiO ₂ was used in the preparation of flame retardant A.

Example 9 (Preparation of Flame Retardant E) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., 90 g of sodium silicate in terms of SiO ₂ was added, and the pH of the slurry was adjusted. Sulfuric acid was added over 1 hour until
The slurry was aged at 80 ° C. for 1 hour to form a coating layer made of high-density silica on the surface of the magnesium hydroxide particles.

Next, a slurry of such magnesium hydroxide particles was added to methylhydrogenpolysiloxane 3
An emulsion containing 0 g was added, and the mixture was stirred at 80 ° C. for 1 hour, then magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried and pulverized to obtain a flame retardant E according to the present invention.
Got

Example 10 (Preparation of flame retardant F) Flame retardant F according to the present invention was prepared in the same manner as in the preparation of flame retardant E, except that an emulsion containing 150 g of methylhydrogenpolysiloxane was used.
Got

Example 11 (Preparation of Flame Retardant G) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C. and 90 g of sodium silicate as SiO ₂ was added.
Sulfuric acid was added over 1 hour until H became 9, and then 8
After aging for 1 hour at 0 ° C., while maintaining the pH 9, Al ₂
15 g of sodium aluminate and sulfuric acid were added in terms of O ₃ and aged for 1 hour to form a coating layer made of high-density silica on the surface of the magnesium hydroxide particles, and further, a coating layer made of alumina was formed thereon. Formed.

Then, a slurry of such magnesium hydroxide particles was added to methylhydrogenpolysiloxane 9
An emulsion containing 0 g was added, and the mixture was stirred at 80 ° C. for 1 hour, then magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried and pulverized to obtain a flame retardant G according to the present invention.
Got

Example 12 (Preparation of flame retardant H) In the preparation of flame retardant G, Al ₂ O
A flame retardant H according to the present invention was obtained in the same manner except that 30 g of sodium aluminate was used in terms of ₃ .

Example 13 (Preparation of Flame Retardant J) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., and 150 g of sodium silicate as SiO ₂ was added. Sulfuric acid is added over 1 hour until
After aging at 80 ° C. for 1 hour, a coating layer made of high-density silica was formed on the surface of the magnesium hydroxide particles.

Thereafter, the slurry of magnesium hydroxide particles was cooled to 40 ° C., an emulsion containing 90 g of methylhydrogenpolysiloxane was added thereto, the mixture was stirred for 1 hour, and the magnesium hydroxide particles were separated from the slurry by filtration. After that, it was washed with water, dried, and pulverized to obtain a flame retardant J according to the present invention.

Example 14 (Preparation of Flame Retardant K) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C. and 150 g of sodium silicate as SiO ₂ was added. Sulfuric acid is added over 1 hour until
After aging at 80 ° C. for 1 hour, a coating layer made of high-density silica was formed on the surface of the magnesium hydroxide particles.

Thereafter, the slurry of magnesium hydroxide particles was heated to 90 ° C., an emulsion containing 90 g of methylhydrogenpolysiloxane was added thereto, and the mixture was stirred at 90 ° C. for 1 hour. Separation by filtration, washing with water, drying and pulverization gave a flame retardant K according to the present invention.

Example 15 (Preparation of Flame Retardant L) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., 90 g of sodium silicate in terms of SiO ₂ was added, and the pH of the slurry was adjusted. Sulfuric acid was added over 1 hour until
After aging at 80 ° C. for 1 hour to form a coating layer made of high-density silica on the surface of the magnesium hydroxide particles, the magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried, and then pulverized.

90 g of methylhydrogenpolysiloxane was added to the magnesium hydroxide particles thus obtained while being dry-stirred at 500 rpm using a Henschel mixer, and mixed for 10 minutes. The magnesium hydroxide particles thus treated were heat treated at 80 ° C. for 1 hour to obtain a flame retardant L according to the present invention.

Example 16 (Preparation of Flame Retardant M) In preparation of flame retardant L, 90 g of methyl hydrogen polysiloxane was added, and the mixture was stirred and mixed for 10 minutes and then heat-treated at 150 ° C. for 1 hour.
Similarly, a flame retardant M according to the present invention was obtained.

Example 17 (Preparation of Flame Retardant W) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., 150 g of sodium silicate in terms of SiO ₂ was added, and the pH of the slurry was adjusted. Sulfuric acid was added over 1 hour until the number reached 9, and the mixture was further aged at 80 ° C. for 1 hour to form a coating layer of high density silica on the surface of the magnesium hydroxide particles.
Magnesium hydroxide particles are separated from the slurry by filtration,
It was washed with water, dried and crushed.

The magnesium hydroxide particles thus obtained were dry-stirred at 500 rpm using a Henschel mixer, and 90 g of methylhydrogenpolysiloxane was added thereto and mixed for 10 minutes. The magnesium hydroxide particles thus treated were heat treated at 150 ° C. for 1 hour to obtain a flame retardant W according to the present invention.

Example 18 (Preparation of Flame Retardant I) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., and 90 g of sodium silicate as SiO ₂ was added.
Sulfuric acid was added over 1 hour until H became 9, and then 8
After aging at 0 ° C. for 1 hour, a coating layer made of high-density silica was formed on the surface of the magnesium hydroxide particles.

Next, 90 g of decyltrimethoxysilane was added to such a slurry of magnesium hydroxide particles, and the mixture was stirred at 80 ° C. for 1 hour. Then, the magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried and pulverized. Then, a flame retardant I according to the present invention was obtained.

Example 19 (Preparation of Flame Retardant O) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., and 90 g of sodium silicate as SiO ₂ was added.
Sulfuric acid was added over 1 hour until H became 9, and then 8
After aging at 0 ° C. for 1 hour, a coating layer made of high-density silica was formed on the surface of the magnesium hydroxide particles.

Next, 0.9 L of a 10 wt% aqueous solution of sodium stearate (90 g of sodium stearate) was added to such a slurry of magnesium hydroxide particles, and the mixture was stirred at 80 ° C. for 1 hour. Was separated by filtration, washed with water, dried and pulverized to obtain a flame retardant O according to the present invention.

Example 20 (Preparation of Flame Retardant V) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., 150 g of sodium silicate as SiO ₂ was added, and the pH of the slurry was adjusted to 9 Sulfuric acid is added over 1 hour until
After aging at 80 ° C. for 1 hour, a coating layer made of high-density silica was formed on the surface of the magnesium hydroxide particles.

Next, 90 g of γ-methacryloxypropyltrimethoxysilane was added to such a slurry of magnesium hydroxide particles, and the mixture was stirred at 80 ° C. for 1 hour, then the magnesium hydroxide particles were separated from the slurry by filtration and washed with water. , Dried and crushed to obtain the flame retardant V according to the present invention.

Example 21 (Preparation of flame retardant X) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., 300 g of sodium silicate in terms of SiO ₂ was added, and the pH of the slurry was adjusted. Sulfuric acid was added over 10 minutes, and the slurry was aged at 80 ° C. for 1 hour to form a coating layer of low-density silica on the surface of the magnesium hydroxide particles.

Then, a slurry of such magnesium hydroxide particles was added to methylhydrogenpolysiloxane 9
An emulsion containing 0 g was added, and the mixture was stirred at 80 ° C. for 1 hour, then magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried and pulverized to obtain a flame retardant X according to the present invention.
Got

Comparative Example 1 (Preparation of Flame Retardant S) Magnesium hydroxide particles were separated from 20 L of magnesium hydroxide aqueous slurry (150 g / L) by filtration, washed with water, dried, and then pulverized. 90 g of methylhydrogenpolysiloxane was added to the magnesium hydroxide particles while they were dry-stirred at 500 rpm using a Henschel mixer, and they were mixed for 10 minutes. The magnesium hydroxide particles thus treated were heat treated at 150 ° C. for 1 hour to obtain a flame retardant S as a comparative example.

Comparative Example 2 (Preparation of Flame Retardant R) 20 L of an aqueous slurry of magnesium hydroxide (150 g / L) was heated to 80 ° C., and 0.9 L of a 10 wt% aqueous solution of sodium stearate (sodium stearate) was added thereto. 90 g) was added and the mixture was stirred at 80 ° C. for 1 hour. Thereafter, magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried and then pulverized to obtain a flame retardant R as a comparative example corresponding to a commercial product.

Comparative Example 3 (Preparation of Flame Retardant P) To 20 L of magnesium hydroxide aqueous slurry (150 g / L) was added 30 g of sodium aluminate in terms of Al ₂ O ₃ , and then hydrochloric acid having a concentration of 1 mol / L was added. After 0.58 L was added over 1 hour, the temperature was raised to 80 ° C., 3 L of a 3 wt% aqueous solution of stearyl alcohol phosphate (stearyl alcohol phosphate 90 g) was added thereto, and the mixture was stirred for 30 minutes. Thereafter, magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried, and then pulverized to obtain a flame retardant P as a comparative example corresponding to a commercially available acid resistant product.

Comparative Example 4 (Preparation of Flame Retardant T) 71 g of sodium hydroxide was added to 20 L of magnesium hydroxide aqueous slurry (150 g / L), and further 4.8 L of aluminum chloride hexahydrate aqueous solution having a concentration of 3% by weight ( After adding 30 g of Al ₂ O ₃ over 30 minutes, the mixture was stirred for 30 minutes. Magnesium hydroxide particles were separated from the slurry by filtration, washed with water, and then redispersed in 20 L of water. The temperature of this slurry was raised to 80 ° C., 3 L of a 3 wt% sodium stearate aqueous solution (90 g of sodium stearate) preheated to 80 ° C. was added thereto, and the mixture was stirred for 30 minutes. Thereafter, magnesium hydroxide particles were separated from the slurry by filtration, washed with water, dried, and then pulverized to obtain a flame retardant T as a comparative example corresponding to a commercially available acid resistant product.

(Preparation of flame-retardant resin composition) Example 22 Polyethylene resin (MFR 1 g / 10 min, melting point 120)
C) 100 parts by weight, as shown in Tables 1 to 4, 100 parts by weight of each of the flame retardants obtained in the above Examples 1 to 21 was added, and a kneader kneader was used for 15 minutes at 160 ° C. After melt-kneading, the resin composition was formed into pellets. The pellets were formed into a sheet with a biaxial roll at 130 ° C., and pressed with a hot press at 160 ° C. for 3 minutes at 50 kgf / cm ² to form a sheet having a thickness of 1.0 mm. This sheet was punched into strips and subjected to an acid resistance test in accordance with JIS K 7114 using 30% by weight sulfuric acid as a test solution. Separately, the above sheet was punched into a strip shape and the oxygen index was measured according to JIS K7201. The results are shown in Tables 1 to 4.

Here, the acid resistance can be evaluated by the weight reduction of the sample, and the lower the value (weight reduction), the better the acid resistance, and the higher the oxygen index, the higher the oxygen index. Shows excellent flame retardancy.

In addition, in each of Examples 1 to 21 above, when the flame retardant was produced, the magnesium hydroxide particles were formed with the coating layer, or after the coating layer was formed and further subjected to the surface treatment, magnesium hydroxide was added. Table 1 to Table 3 show the separation time and the water washing time when the particles are filtered. Here, the separation time means that a water slurry of magnesium hydroxide is added to the filter paper No. It means the time required from the start of filtration using 5C until the drop of the filtrate reaches 5 drops / minute, and the water washing time means the magnesium hydroxide particles filtered from the slurry in a certain amount of water (10 L). It is the separation time defined above when the slurry is dispersed into a slurry and filtered.

Comparative Example 5 100 parts by weight of the same polyethylene resin as used in Example 22 was added with 100 parts by weight of each flame retardant obtained in Comparative Examples 1 to 5 as shown in Table 4, In the same manner as in 22, a sheet was obtained from the resin composition, subjected to an acid resistance test, and the oxygen index was measured. The results are shown in Table 4. In addition, in Comparative Examples 1 to 4, Table 4 shows the separation time and the water washing time according to the above definitions when manufacturing the flame retardant.

Comparative Example 6 A sheet was prepared in the same manner as in Example 22 without adding a flame retardant to the same polyethylene resin as that used in Example 22, and was subjected to an acid resistance test, and the oxygen index was measured. . The results are shown in Table 4 as blanks.

[0104]

[Table 1]

[0105]

[Table 2]

[0106]

[Table 3]

[0107]

[Table 4]

As shown in Tables 1 to 4, the resin composition containing the flame retardant according to the present invention has high acid resistance. In particular, a flame retardant obtained by forming a coating layer made of silica on the surface of magnesium hydroxide particles and further surface-treating such magnesium hydroxide particles has excellent acid resistance. Above all, the coating layer made of silica is made of high-density silica, and the flame retardant formed by surface treatment with polysiloxane has particularly excellent acid resistance.

In the production of the flame retardant according to the present invention, the filterability of magnesium hydroxide particles can be improved by forming a coating layer made of silica and then forming a second coating layer made of alumina, for example. Significantly improved.

On the other hand, the flame retardant S in which the magnesium hydroxide particles are only surface-treated with polysiloxane and the flame retardant R in which the magnesium hydroxide particles are only surface-treated with sodium stearate are inferior in acid resistance. . Similarly, flame retardants P and T obtained by forming a coating layer made of alumina on the surface of magnesium hydroxide particles and further surface-treating it with stearyl alcohol phosphate or sodium stearate also have poor acid resistance. ing.

[0111]

As described above, the flame retardant according to the present invention is
It has a coating layer made of silica on the surface, and preferably further comprises magnesium hydroxide particles surface-treated with the surface-treating agent, and when blended with a resin to give a flame-retardant resin composition. Gives high acid resistance to the resin composition. Therefore, the flame-retardant resin composition obtained by blending the flame-retardant agent according to the present invention with a resin is not only flame-retardant but also very excellent in acid resistance, and is used for building materials and electric wire coating materials, particularly acidic chemicals It can be suitably used for chemical plant applications where there are many opportunities to come into contact with acid gas and the like and outdoor applications where it is exposed to acid rain and the like. Further, it can be suitably used for applications such as lithography resists that are subjected to acid cleaning.

Of course, the flame retardant according to the present invention is not limited in its application, and besides the above, it can be suitably used for the production of various molded products such as electric parts, automobile parts and pipes. it can.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Mori             5-1, Ebishimacho, Sakai City, Osaka Prefecture Sakai Chemical Industry             Within the corporation F-term (reference) 4H028 AA10 AB02 BA06                 4J002 AC031 AC061 AC071 AC091                       BB031 BB051 BB061 BB071                       BB121 BB151 BC031 BC051                       BD041 BF031 BG041 BG061                       BG111 BN151 CB001 CF061                       CF071 CG001 CH071 CL011                       CL031 CL061 DE076 FB076                       FD136 GN00 GQ00 GQ01

Claims (12)

[Claims] 1. A flame retardant comprising magnesium hydroxide particles, which has a coating layer consisting of 0.1 to 20% by weight of silica in terms of SiO _{2 with} respect to magnesium hydroxide on the surface. 2. Al ₂ O ₃ , TiO ₂ and ZrO on magnesium hydroxide on a coating layer made of silica, respectively.
_{The second} coating layer made of at least one selected from alumina, titania and zirconia in terms of 2 to 0.03 to
The flame retardant according to claim 1, which has a range of 10% by weight. 3. A coating layer made of silica further comprises Al ₂ O ₃ , TiO ₂ and ZrO for magnesium hydroxide, respectively.
Flame retardant according to claim 1 having the alumina in ₂ equivalent, at least one second oxide selected from titania and zirconia in the range of 0.03 to 10 wt%. 4. Magnesium hydroxide particles having a coating layer composed of 0.1 to 20% by weight of silica in terms of SiO _{2 with} respect to magnesium hydroxide on the surface thereof are higher fatty acids, higher fatty acid alkali metal salts and polyhydric alcohols. Surface with at least one surface treatment agent selected from higher fatty acid ester, anionic surfactant, phosphate ester, silane coupling agent, aluminum coupling agent, titanate coupling agent, organosilane, organosiloxane and organosilazane Flame retardant obtained by treatment. 5. Al ₂ O ₃ , TiO ₂ and ZrO are added to magnesium hydroxide on a coating layer made of silica, respectively.
_{The second} coating layer made of at least one selected from alumina, titania and zirconia in terms of 2 to 0.03 to
The flame retardant according to claim 4, which has a content of 10% by weight. 6. A coating layer made of silica further comprises Al ₂ O ₃ , TiO ₂ and ZrO for magnesium hydroxide, respectively.
Flame retardant of claim 4 having the alumina in ₂ equivalent, at least one second oxide selected from titania and zirconia in the range of 0.03 to 10 wt%. 7. A magnesium hydroxide particle surface is provided with a coating layer made of 0.1 to 20% by weight of silica in terms of SiO _{2 with} respect to magnesium hydroxide, and then a higher fatty acid or higher fatty acid alkali. At least one selected from metal salts, polyhydric alcohol higher fatty acid esters, anionic surfactants, phosphoric acid esters, silane coupling agents, aluminum coupling agents, titanate coupling agents, organosilanes, organosiloxanes and organosilazanes. A method for producing a flame retardant, which comprises performing a surface treatment with a surface treatment agent. 8. Al ₂ O ₃ , TiO ₂ and Z for magnesium hydroxide respectively on a silica coating layer.
The second coating layer of at least one selected from alumina, titania and zirconia is converted to 0.0 in terms of rO _2.
The method for producing a flame retardant according to claim 7, wherein the flame retardant is formed in the range of 3 to 10% by weight. 9. A silica coating layer further comprises Al ₂ O ₃ , TiO ₂ and ZrO for magnesium hydroxide, respectively.
_The method for producing a flame retardant according to claim 7, which comprises at least one second oxide selected from alumina, titania, and zirconia in terms of 2 in the range of 0.03 to 10% by weight. 10. A magnesium hydroxide of 0.1 to 2
Using 0% by weight of the surface treatment agent, a temperature of 20 to 95 ° C., p
The method for producing a flame retardant according to any one of claims 7 to 9, wherein the surface treatment is performed with H6 to 12 by a wet method. 11. A magnesium hydroxide of 0.1 to 2
The method for producing a flame retardant according to any one of claims 7 to 9, wherein the surface treatment is performed by a dry method at a temperature of 5 to 300 ° C using 0% by weight of the surface treatment agent. 12. A flame-retardant resin composition comprising 100 parts by weight of a resin and 5 to 350 parts by weight of the flame retardant according to any one of claims 1 to 6.