JP3749682B2 - Magnesium hydroxide flame retardant, method for producing the same, and flame retardant resin composition using the flame retardant - Google Patents

Description

【００３０】
合格ラインはそれぞれ、酸素指数で30以上、引張強度で10Mpa以上、引張伸びで200%以上、体積固有抵抗(含浸96時間後)で1.0×1014Ω・cm以上とした。なお酸素指数は実施例1〜3，比較例1〜７とも30以上であったので、表1には示さなかった。
【００３１】
表1から明らかなように、表面処理剤をステアリン酸とすると引張強度や引張伸びの他に、耐水試験後の体積固有抵抗が不足する(比較例1)。表面処理剤をシランカップリング剤のみとする、あるいは撹拌処理温度が220℃を超えると、耐水試験後の体積固有抵抗が不足する(比較例2,6)。表面処理剤をアルコールリン酸エステルのみとする、あるいは非加熱や100℃で撹拌する、またメディア型のミルではなく撹拌型のヘンシェルミキサーを用いると、引張強度や引張伸びが不足する(比較例3,4,5,7)。これに対して実施例では、機械的物性及び耐水性に優れた難燃剤や難燃性樹脂組成物が得られる。
【００３２】
実施例では、特定のシランカップリング剤（γ-メタクリロキシプロピルトリメトキシシラン約１重量％）を用いたが、シランカップリング剤の種類は任意である。また特定のアルコールリン酸エステル（モノ-ステアリルアルコールリン酸エステルとジ-ステアリルアルコールリン酸エステルの1:1混合物約１重量%）を用いたが、アルコールリン酸エステルの種類を変えても、１〜２基の飽和アルコールによりリン酸エステルの水素イオンを置換し、かつ１個の残存水素イオンを有するものであれば、ほぼ同等の結果が得られた。オレフィン樹脂には、エチレン・アクリル酸エチル・無水マレイン酸三元共重合体を用いたが、オレフィン樹脂の種類は任意である。表１から明らかなように、決定的に重要なのは以下の点で、これ以外の点は適宜に変更できる。
・ シランカップリング剤とアルコールリン酸エステルとを併用すること、
・ メディアミルを用いて粉砕と表面処理とを同時に行うこと、
・ 表面処理温度を120℃〜220℃とすること。
【００３３】
表1には示さなかったが、シランカップリング剤が水酸化マグネシウムと表面処理剤の合計量の0.5重量%未満では、引張強度が不足して好ましくない。シランカップリング剤が水酸化マグネシウムと表面処理剤の合計量の5重量%を超えると、引張伸びが不足して好ましくない。アルコールリン酸エステルが水酸化マグネシウムと表面処理剤の合計量の0.5重量%未満では、耐水試験後の体積固有抵抗が不足して好ましくない。アルコールリン酸エステルが水酸化マグネシウムと表面処理剤の合計量の5重量%を超えると、引張強度と引張伸びが不足して好ましくない。天然ブルーサイト鉱石の粗粉体の平均粒子径が8μmを超えると、引張強度が不足し好ましくない。天然ブルーサイト鉱石の粗粉体は、表面処理剤と共に粉砕するのであるから、粉砕前の平均粒子径が5μm超であることが好ましい。
【００３４】
【発明の効果】
本発明では、樹脂配合時の機械的物性及び耐水性に優れ、かつ低コストで経済性に優れた水酸化マグネシウム系難燃剤が得られる。この難燃剤を配合することにより、幅広い用途で、環境に優しいノンハロゲン難燃材料によりハロゲン系材料を代替することが可能となる。[0001]
[Field of the Invention]
The present invention relates to a magnesium hydroxide flame retardant used as a non-halogen flame retardant material, a method for producing the same, and a flame retardant resin composition using the flame retardant. More specifically, the present invention provides a magnesium hydroxide flame retardant which is excellent in mechanical properties and water resistance of a resin composition when blended with a polyolefin resin and is relatively inexpensive.
[0002]
[Prior art]
Magnesium hydroxide is an olefin-based resin composition for the purpose of preventing secondary disasters such as fuming, toxicity, and corrosion during combustion of the resin composition as disclosed in, for example, JP-A-1-41929. It has been added to. Magnesium hydroxide is a non-halogen flame retardant, and in line with the social needs of global environmental conservation and ecology, the resin composition using magnesium hydroxide does not contain halogens or heavy metals. As a material, it is being widely applied mainly for the use of electric wire coating used in automobile wire harnesses and the like.
[0003]
Magnesium hydroxide production methods used for such non-halogen flame retardant applications can be broadly divided into two methods: reaction synthesis and natural mineral grinding. The reaction synthesis method includes, for example, a method of reacting by adding a caustic or slaked lime slurry in seawater or bitter juice, a method of adding sodium hydroxide to a magnesium hydroxide slurry and hydrothermally treating it (Japanese Patent Publication No. 50-23680) A method of hydrothermally treating a basic magnesium salt slurry (Japanese Patent Laid-Open No. 52-115799) and a method of reacting a magnesium salt solution with ammonia (Japanese Patent Laid-Open No. 61-168522, etc.) are known. In any method, the synthesized magnesium hydroxide is washed, surface-treated, dehydrated, dried and pulverized to obtain a magnesium hydroxide flame retardant.
[0004]
On the other hand, the natural mineral pulverization method is a method in which natural brucite ore mainly composed of magnesium hydroxide is pulverized and surface-treated to form a magnesium hydroxide flame retardant. For example, it is disclosed in Japanese Patent Publication No. 7-42461. As known in the art, natural brucite ore is made into an aqueous slurry, wet pulverized, this pulverized product slurry is surface-treated with an emulsion of fatty acid ammonium salt or amine salt, solid-liquid separated, and then dried. It has been.
[0005]
Further, as disclosed in, for example, JP-A-7-16230, in order to suppress the hygroscopicity of the flame retardant composition, natural brucite ore is pulverized, fatty acid, fatty acid metal salt, silane coupling agent, titanate A method of performing a surface treatment with a surface treatment agent containing a coupling agent as a main component is known. Further, JP-A-10-226789 discloses a natural brucite pulverized product as a silane coupling agent in order to obtain a relatively low cost magnesium hydroxide flame retardant having excellent water resistance, dispersibility and flame retardancy. And a method for producing a magnesium hydroxide flame retardant having an average particle diameter of 1 to 10 μm, which is mechanochemically treated in the presence of a silane surface treatment agent and the coating layer and the particle surface are chemically bonded.
[0006]
[Problems of the prior art]
For non-halogen flame retardant materials obtained by blending magnesium hydroxide flame retardant, magnesium hydroxide flame retardant, for example, 50-100 parts by weight with respect to 100 parts by weight of resin, high flame resistance is required Is added in an amount of 100 parts by weight or more. As the blending amount of the magnesium hydroxide flame retardant increases, the flame resistance is improved, but the mechanical properties are lowered. In particular, when high flame retardancy is required, this tendency is conspicuous in a high filling blend of 100 parts by weight or more of a magnesium hydroxide flame retardant, and the blending design of the flame retardant material becomes difficult. It has been found that not only the compounding amount of magnesium hydroxide flame retardant but also the properties of magnesium hydroxide flame retardant affect the mechanical properties degradation, and the mechanical properties are less degraded even with high filling. There is a need for magnesium hydroxide flame retardants.
[0007]
Of the magnesium hydroxide flame retardants, magnesium hydroxide obtained by reactive synthesis has relatively uniform particle properties and relatively fine and uniform particle size, so that it has relatively mechanical properties even when filled at high levels. It has the characteristic that it is easy to make a material with a small drop. However, compared to the natural mineral grinding method, the raw material cost is high, the manufacturing process is complicated, and it is economically disadvantageous because it requires a process with high energy cost, and the uses that are used as non-halogen flame retardants are limited. It must be a thing.
[0008]
On the other hand, a magnesium hydroxide flame retardant produced by a natural mineral pulverization method is expected to be an economical material with relatively low cost because it uses inexpensive natural brucite ore as a raw material. In particular, a method comprising only a dry process as disclosed in Japanese Patent Application Laid-Open No. 7-126230 and Japanese Patent Application Laid-Open No. 10-226789 is an environment-friendly non-halogen flame retardant material that replaces halogen-based materials for a wide range of applications. Expected to get.
[0009]
However, the flame retarding effect of the magnesium hydroxide flame retardant is lower than that of the halogen flame retardant. When blended in a polyolefin resin or the like, sufficient flame retardancy cannot be obtained unless blended in a large amount in the resin. For example, an insulated wire used for an automobile wire harness is required to have flame retardancy that passes a ISO 45 ° inclining combustion test from the viewpoint of safety against fire accidents. In order to pass such a combustion test, generally a large amount of magnesium hydroxide flame retardant is blended in the resin to increase the flame retardancy, but the dispersibility deteriorates and the tensile strength and elongation of the resin composition are reduced. The mechanical properties such as
[0010]
As a method for solving such a problem, for example, in Patent No. 2525968, a large amount of magnesium hydroxide is blended without deteriorating mechanical properties. Therefore, a crosslinking agent such as a silane coupling agent is blended and melted. A method of performing chemical crosslinking or electron beam crosslinking during kneading or extrusion is shown. Further, for example, Japanese Patent Application Laid-Open No. 2000-294036 discloses that when a predetermined amount of magnesium hydroxide surface-treated with a crosslinkable silane coupling agent is blended, high flame retardancy and mechanical properties can be satisfied.
[0011]
Moreover, in the flame-retardant resin composition used for coating such as a wire harness, water resistance is an important characteristic along with mechanical properties. That is, when exposed to rainwater, moisture, or the like for a long time, the electrical insulation of the wire coating material is lowered, and there is a risk of short-circuiting or electric leakage. However, magnesium hydroxide flame retardant surface-treated only by a simple dry process as disclosed in JP-A-7-126230 and JP-A-10-226789 sufficiently satisfies mechanical properties and water resistance. could not.
[0012]
[Problems of the Invention]
An object of the present invention is to provide a magnesium hydroxide flame retardant excellent in mechanical properties and water resistance when blended with a resin, and at low cost and excellent in economic efficiency, a method for producing the same, and a resin composition using the flame retardant To provide things.
[0013]
[Means for Solving the Problems]
The inventor has reached the present invention as a result of earnest examination of each element of the above-mentioned problems. That is, in the method of dry pulverizing natural brucite ore, two types of surface treatment agents consisting of a silane coupling agent and an alcohol phosphate ester are added to the natural brucite ore powder, and 150 mils are added using a media pulverizer. It has been found that the object of the present invention can be achieved by simultaneously performing pulverization and surface treatment while heating to ˜250 ° C. to obtain a predetermined average particle size.
[0014]
In the present invention, in a method for producing a magnesium hydroxide flame retardant by dry pulverizing natural brucite ore, two types of surfaces comprising a silane coupling agent and an alcohol phosphate ester are used on the natural brucite ore coarse powder. Using a media pulverizer capable of heating the object to be crushed by adding a treatment agent, pulverization and surface treatment are simultaneously performed while heating to 120 to 220 ° C., and the average particle diameter is 1 μm or more and 5 μm or less. The particles have a coating layer of a surface treatment agent.
The average particle diameter is preferably 2 to 5 μm, the average particle diameter of the coarse powder is, for example, more than 5 μm and 8 μm or less, and the respective addition amounts of the silane coupling agent and the alcohol phosphate ester are magnesium hydroxide and a surface treatment agent. Preferably, the content is 0.5 to 5% with respect to the total amount. The heating temperature is 120 to 220 ° C, preferably 150 to 200 ° C. According to the present invention, a magnesium hydroxide flame retardant having excellent mechanical properties and water resistance at the time of blending a resin, low cost and excellent economy is provided.
[0015]
Examples of the silane coupling agent used in the present invention include γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, and the like. Methacryloxy, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, etc., vinyl, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycol Epoxy systems such as Sidoxypropyltriethoxysilane, β- (3,4 Epoxycyclohexyl) ethyltrimethoxysilane, N-β (Aminoethyl) γ-Aminopropylmethyldimethoxysilane, N-β (Aminoethyl) γ-Amino Propyltrimethoxysilane, N-β ( Minoechiru) .gamma.-aminopropyltriethoxysilane, .gamma.-aminopropyltrimethoxysilane, .gamma.-aminopropyltriethoxysilane, amino-based such as N- phenyl--γ- aminopropyltrimethoxysilane.
[0016]
The alcohol phosphate ester may be an ester of alcohol and phosphoric acid, for example, a monoalcohol ester or a dialcohol ester, and residual hydrogen ions in phosphoric acid (hydrogen ions remaining without esterification reaction) are alkali metal ions or You may substitute by alcohol amine ion etc. However, in the present invention, alcohol phosphate ester is reacted with magnesium hydroxide in a dry manner under heating, so that the position of residual hydrogen ion becomes the reaction position with magnesium hydroxide, and the residual hydrogen ion in phosphoric acid is converted to alkali metal ion. Substitution with alcohol amine ions or the like is not preferable because the reactivity with the magnesium hydroxide surface decreases.
[0017]
The alcohol phosphate ester used in the present invention is preferably a mono- or di-saturated alcohol phosphate ester, and a trialcohol phosphate ester is not preferred because of its low reactivity with magnesium hydroxide. Such alcohol phosphates include, for example, mono-stearyl alcohol phosphate, di-stearyl alcohol phosphate, mono-lauryl alcohol phosphate, di-lauryl alcohol phosphate, mono-myristyl alcohol phosphate , Di-myristyl alcohol phosphate, mono-palmityl alcohol phosphate, di-palmityl alcohol phosphate, mono-aralkyl alcohol phosphate, di-aralkyl alcohol phosphate, mono-beher alcohol There are phosphoric acid ester, di-beher alcohol phosphoric acid ester, mono-lignoseryl alcohol phosphoric acid ester, di-lignoseryl alcohol phosphoric acid ester and the like, which are used alone or in combination.
[0018]
In the medium pulverizer (media mill) having a structure capable of heating the object to be pulverized in the present invention, for example, a container containing the object to be pulverized is heated by a jacket, and the object to be pulverized and the medium are transferred into the container. Use the one that can be moved. Specific examples include a batch type or continuous type ball mill, a vibrating ball mill, a media agitation type mill, and the like. For example, the media is heated by jacket heating, and the media includes water such as alumina balls, zirconia balls, metal balls, and metal rods. Media harder than magnesium oxide can be used.
[0019]
The treatment temperature in the media grinder of the present invention is 120 to 220 ° C, preferably 150 to 200 ° C. When the temperature is lower than 120 ° C., the mechanical properties are insufficient. When the temperature is higher than 220 ° C., the surface treatment agent is burnt and the resin composition is colored, and the water resistance is also lowered.
[0020]
The magnesium hydroxide flame retardant of the present invention is blended in maleic anhydride, acrylic acid, vinyl acetate, ethylene and propylene resins and copolymer resins thereof. Naturally, the suitable conditions regarding a magnesium hydroxide flame retardant also apply to the resin composition to which the flame retardant is added.
[0021]
【Example】
Examples (Examples 1 to 3) in which a silane coupling agent and an alcohol phosphate ester are used in combination as a surface treatment agent and pulverized with heating at 120 to 220 ° C. using a media mill are shown below. As a comparative example, one not using a silane coupling agent and an alcohol phosphate ester (Comparative Example 1) or one using only one of these (Comparative Examples 2 and 3) is shown. Comparative Examples 4 to 6 show the media mill surface treatment temperature (mill internal temperature) at room temperature, 100 ° C., or 250 ° C. Further, instead of the media mill, Comparative Example 7 shows what is stirred with heating with a Henschel mixer and pulverized with a hammer mill.
[0022]
[Example 1]
1 kg of natural brucite coarsely pulverized product with an average particle size of 6 μm, 10 g of γ-methacryloxypropyltrimethoxysilane, a mixture of mono-stearyl alcohol phosphate and di-stearyl alcohol phosphate (50% by weight) : 50 wt%) 10 g was placed in a jacket-type batch media stirring mill with an internal volume of 10 liters, heated to 150 ° C., and stirred for 30 minutes. Alumina balls with a diameter of 5 mm were used for the mill media. After the treatment, the powder was taken out from the batch-type media stirring mill and used as a surface-treated product sample.
[0023]
[Examples 2 and 3]
A surface-treated product sample was obtained in the same manner as in Example 1 except that the temperature inside the media stirring mill was 200 ° C. (Example 2) or 210 ° C. (Example 3).
[0024]
[Comparative Examples 1 and 2]
A surface-treated sample was obtained in the same manner as in Example 1 except that the surface treating agent was only 10 g of stearic acid (Comparative Example 1). A surface treatment sample was obtained in the same manner as in Example 1 except that the surface treatment agent was only 10 g of γ-methacryloxypropyltrimethoxysilane (Comparative Example 2). Further, the surface treatment agent was treated in the same manner as in Example 1 except that the surface treatment agent was only 10 g of a mixture of mono-stearyl alcohol phosphate and di-stearyl alcohol phosphate (weight ratio: 50% by weight: 50% by weight). A treated sample was obtained (Comparative Example 3).
[0025]
[Comparative Examples 4-6]
Using a media stirring mill, non-heated during the stirring process (Comparative Example 4), the temperature inside the mill during the stirring process was set to 100 ° C. (Comparative Example 5), or the temperature inside the mill was set to 250 ° C. (Comparative Example 6) Otherwise, a surface treatment sample was obtained in the same manner as Example 1.
[0026]
[Comparative Example 7]
1 kg of natural brucite crude product having an average particle size of 6 μm, 10 g of γ-methacryloxypropyltrimethoxysilane, a mixture of mono-stearyl alcohol phosphate and di-stearyl alcohol phosphate (50% by weight) : 50 wt%) 10 g was put in a 10 liter Henschel mixer (mixer with stirring type and without media), dry-mixed for 5 minutes, heated to 150 ° C., and stirred at high speed for 30 minutes. The stirring was stopped 10 minutes after the start of high-speed stirring, and the operation of scraping off the deposits on the inner wall and the stirring wall was performed once. The powder that had been heated and mixed with the Henschel mixer was pulverized with a hammer mill, and then again heated and mixed at about 150 ° C. for 15 minutes in a Henschel mixer to obtain a surface-treated sample.
[0027]
The average particle diameter of the surface-treated magnesium hydroxide (magnesium hydroxide flame retardant) obtained in Examples 1 to 3 and Comparative Examples 1 to 7 was measured by a laser diffraction method. The average particle size was measured after ultrasonically dispersing the sample in special grade ethanol.
[0028]
Next, with respect to 100 parts by weight of ethylene / ethyl acrylate / maleic anhydride terpolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bondine TX-8030, MFR: 3), hydroxylation prepared in Examples and Comparative Examples After mixing and mixing 100 parts by weight of a magnesium surface-treated product, the mixture was kneaded at 150 ° C. for 5 minutes at a rotation speed of 50 rpm using a Laboplast mill manufactured by Toyo Seiki Co., Ltd., and further press molded at 150 ° C. In the flame retardancy test, a sheet having a thickness of 3 mm was prepared, a test piece having a length of 150 mm and a width of 6.5 mm was prepared, and the oxygen index (based on JIS K7201) was measured. The tensile test was performed in accordance with JIS K7113 using a sheet with a thickness of 2 mm and punched into a dumbbell shape. In addition, the water resistance test was conducted by preparing a sheet having a thickness of 1 mm × length 130 mm × width 130 mm, and heating the sheet in 10% by weight saline (pure water 90% by weight: salt 10% by weight) heated to 80 ° C. After impregnating for a period of time, the surface of the sheet is dried for 8 hours at 40 ° C., left for 3 hours in an atmosphere of 30 ° C. and 50% relative humidity, and then a voltage of 500 V is applied to measure the current value after 1 minute. Volume resistivity was calculated (based on JIS K7194). These results are shown in Table 1.
[0029]
[Table 1]

[0030]
Each of the passing lines had an oxygen index of 30 or more, a tensile strength of 10 Mpa or more, a tensile elongation of 200% or more, and a volume resistivity (after 96 hours of impregnation) of 1.0 × 10 14 Ω · cm or more. Since the oxygen index was 30 or more in Examples 1 to 3 and Comparative Examples 1 to 7, they were not shown in Table 1.
[0031]
As is apparent from Table 1, when the surface treatment agent is stearic acid, in addition to the tensile strength and tensile elongation, the volume resistivity after the water resistance test is insufficient (Comparative Example 1). When the surface treatment agent is only the silane coupling agent or the stirring treatment temperature exceeds 220 ° C., the volume resistivity after the water resistance test is insufficient (Comparative Examples 2 and 6). If the surface treatment agent is alcohol phosphate ester only, or it is not heated or stirred at 100 ° C, or if a stirring type Henschel mixer is used instead of a media type mill, the tensile strength and tensile elongation will be insufficient (Comparative Example 3 , 4,5,7). On the other hand, in an Example, the flame retardant and flame retardant resin composition excellent in mechanical physical property and water resistance are obtained.
[0032]
In the examples, a specific silane coupling agent (about 1% by weight of γ-methacryloxypropyltrimethoxysilane) was used, but the type of silane coupling agent is arbitrary. In addition, a specific alcohol phosphate ester (about 1% by weight of a 1: 1 mixture of mono-stearyl alcohol phosphate ester and di-stearyl alcohol phosphate ester) was used. When the hydrogen ions of the phosphate ester were substituted with ˜2 saturated alcohols and had one residual hydrogen ion, almost the same result was obtained. As the olefin resin, an ethylene / ethyl acrylate / maleic anhydride terpolymer was used, but the type of the olefin resin is arbitrary. As is clear from Table 1, the following points are critical and other points can be changed as appropriate.
・ Combined use of silane coupling agent and alcohol phosphate ester,
・ Simultaneous grinding and surface treatment using a media mill,
・ The surface treatment temperature should be 120 to 220 ° C.
[0033]
Although not shown in Table 1, if the silane coupling agent is less than 0.5% by weight of the total amount of magnesium hydroxide and the surface treatment agent, the tensile strength is insufficient, which is not preferable. When the silane coupling agent exceeds 5% by weight of the total amount of magnesium hydroxide and the surface treatment agent, the tensile elongation is insufficient, which is not preferable. If the alcohol phosphate is less than 0.5% by weight of the total amount of magnesium hydroxide and the surface treatment agent, the volume resistivity after the water resistance test is insufficient, which is not preferable. When the alcohol phosphate exceeds 5% by weight of the total amount of magnesium hydroxide and the surface treatment agent, the tensile strength and the tensile elongation are insufficient, which is not preferable. When the average particle size of the natural brucite ore coarse powder exceeds 8 μm, the tensile strength is insufficient, which is not preferable. Since the coarse powder of natural brucite ore is pulverized together with the surface treatment agent, the average particle diameter before pulverization is preferably more than 5 μm.
[0034]
【The invention's effect】
In the present invention, a magnesium hydroxide flame retardant excellent in mechanical properties and water resistance at the time of resin blending, low cost and excellent in economic efficiency can be obtained. By blending this flame retardant, it is possible to replace halogen-based materials with environmentally friendly non-halogen flame retardant materials in a wide range of applications.

Claims (4)

Crude natural brucite ore powder is pulverized in the temperature range of 120-220 ° C using a heatable media grinder in the presence of two surface treatment agents consisting of a silane coupling agent and an alcohol phosphate ester. And a particle surface treatment, a magnesium hydroxide flame retardant comprising particles having an average particle diameter of 1 μm to 5 μm and a coating layer of the surface treatment agent. The addition amount of the silane coupling agent is 0.5 to 5% by weight based on the total amount of the natural brucite coarse powder and the surface treatment agent, and the addition amount of the alcohol phosphate is natural brucite coarse powder. The hydroxylation according to claim 1, characterized in that it is 0.5 to 5% by weight based on the total amount of the body and the surface treatment agent, and the average particle size of the natural brucite coarse powder is more than 5 µm and not more than 8 µm. Magnesium flame retardant. Crude natural brucite ore powder is pulverized in the temperature range of 120-220 ° C using a heatable media grinder in the presence of two surface treatment agents consisting of a silane coupling agent and an alcohol phosphate ester. And a particle surface treatment at the same time, and a method for producing a magnesium hydroxide-based flame retardant, wherein the particles have an average particle diameter of 1 μm to 5 μm and have a coating layer of the surface treatment agent. Crude natural brucite ore powder is pulverized in the temperature range of 120-220 ° C using a heatable media grinder in the presence of two surface treatment agents consisting of a silane coupling agent and an alcohol phosphate ester. Flame retardant obtained by kneading a magnesium hydroxide flame retardant comprising particles having an average particle diameter of 1 μm or more and 5 μm or less and having a coating layer of the surface treatment agent, and an olefin resin. Resin composition.