JP2007261923A - Magnesium hydroxide-based powder, its manufacturing method, resin composition and molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide magnesium hydroxide-based powder which does not hydrolyze an ester resin when blended with the ester resin. <P>SOLUTION: The magnesium hydroxide-based powder is obtained by forming a covering layer of a mixture of an Si compound and an Al compound on a synthesized magnesium hydroxide particle, which has the BET specific surface area of ≥0.1 m<SP>2</SP>/g and <1 m<SP>2</SP>/g and the average particle size of >5 μm and ≤20 μm and the [101]/[001] peak intensity ratio of which is ≥0.9 when measured by an X-ray diffraction method, by the ratio of 0.2-10 mass% ((the Si compound)+(the Al compound)) in terms of SiO<SB>2</SB>and Al<SB>2</SB>O<SB>3</SB>to 100 mass% magnesium hydroxide. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnesium hydroxide-based powder blended in an ester-based resin and the like, a method for producing the same, and the obtained resin composition and molded body.

  Synthetic resins having ester bonds (hereinafter referred to as ester resins) include polylactic acid resins, polybutylene terephthalate resins, polyethylene terephthalate resins, and polycarbonate resins, and also include synthetic elastomers having ester bonds. By the way, although aluminum hydroxide and magnesium hydroxide are generally used for non-halogen flame retardants and tracking resistance agents, aluminum hydroxide is concerned about foaming due to dehydration decomposition during high-temperature processing of the resin. Silica having no alkali surface has good hydrolysis resistance of the ester-based resin, but does not exhibit an effect as a flame retardant or tracking resistance. Next, the inventors have found that when magnesium hydroxide is blended with an ester-based resin, the surface of the magnesium hydroxide is alkaline and the resin may be hydrolyzed.

  A basic object of the present invention is to provide a magnesium hydroxide-based powder that does not hydrolyze an ester-based resin, a method for producing the same, and a resin composition and a molded body that contain this magnesium hydroxide-based powder.

The magnesium hydroxide powder of the present invention has a BET specific surface area of 0.1 m ² / g or more and less than 1 m ² / g, an average particle diameter of more than 5 μm and 20 μm or less, and [101] / [001] peak intensity in X-ray diffraction ratio to 0.9 or more synthetic magnesium hydroxide particles, a mixed coating layer of Si compound and Al compound, relative to 100 wt% of magnesium hydroxide in a total amount of SiO ₂ and Al ₂ O ₃ in terms of 0.2 to 10 mass % Formed.
Preferably, the magnesium-based powder hydroxide, BET specific surface area of 0.1m ² /g~0.8m ² / g, an average particle diameter of the 5.5Myuemu～20myuemu.
In this specification, the description regarding the magnesium hydroxide-based powder also applies to the production method, the resin composition, and the molded body as it is unless the context is unnatural.

  Preferably, the magnesium hydroxide particles in which the mixed coating layer of the Si compound and the Al compound is further formed of hardened oil, fatty acid ester, silane coupling agent, silicon oil, phosphate ester, surfactant, and polymer flocculant. Surface treatment is performed at a ratio of 0.1 to 10% by mass with respect to 100% by mass of magnesium hydroxide by at least one kind.

  Preferably, the Si compound is at least one compound of the group consisting of sodium silicate, colloidal silica, and precursors thereof, and the Al compound is aluminum chloride, aluminum sulfate, aluminum nitrate, sodium aluminate, alumina sol and At least one compound of the group consisting of these precursors.

In the method for producing a magnesium hydroxide powder of the present invention,
As a raw material for magnesium hydroxide particles, an aqueous suspension of magnesium hydroxide or magnesium oxide, or an aqueous solution of magnesium chloride, magnesium sulfate or magnesium nitrate,
When the raw material of the magnesium hydroxide particles is an aqueous suspension of magnesium hydroxide or magnesium oxide, wet pulverization is performed by adding lithium hydroxide or sodium hydroxide in a molar ratio of OH ⁻ / Mg ²⁺ of 5 or more. And
When the raw material of the magnesium hydroxide particles is an aqueous solution of magnesium chloride, magnesium sulfate or magnesium nitrate, lithium hydroxide or sodium hydroxide is added in a molar ratio of OH ⁻ / Mg ²⁺ of 5 or more,
In either case, after addition of lithium hydroxide or sodium hydroxide, by hydrothermal treatment at 200-270 ° C,
Synthetic magnesium hydroxide particles having a BET specific surface area of 0.1 m ² / g or more and less than 1 m ² / g, an average particle diameter of more than 5 μm and 20 μm or less, and a [101] / [001] peak intensity ratio in X-ray diffraction of 0.9 or more ,
Surface treatment of the obtained synthetic magnesium hydroxide, mixed coating layer of Si compound and Al compound, 0.2-10 mass with respect to 100 mass% of magnesium hydroxide in the total amount of SiO ₂ and Al ₂ O ₃ conversion Form at a rate of%.

Moreover, the resin composition of this invention mix | blends 5-500 mass parts of magnesium hydroxide type powder in any one of Claims 1-3 with respect to 100 mass parts of synthetic resins which have an ester bond.
Moreover, this invention exists in the molded object of the resin composition of Claim 5.

BET specific surface area of the magnesium hydroxide particles is limited to less than 1 m ² / g at 0.1 m ² / g or more, preferably 0.1m ² /g~0.8m ² / g. When the BET specific surface area is less than 0.1 m ² / g, sufficient flame retardancy cannot be obtained. On the contrary, in the case of 1 m ² / g or more, since the uniform coating with the surface treatment agent is not performed, the pH of the magnesium hydroxide particles is high, and the ester resin is hydrolyzed by the alkalinity of the magnesium hydroxide surface, The handling of the resin composition is lowered, and there is a concern that the original characteristics (impact resistance, etc.) of the resin may be lowered. Moreover, acid resistance is also low.

  The average particle size of the magnesium hydroxide particles is more than 5 μm and limited to 20 μm or less, and preferably 5.5 μm to 20 μm. When the average particle size exceeds 20 μm, sufficient flame retardancy cannot be obtained. Conversely, when the average particle size is 5 μm or less, since the uniform coating with the surface treatment agent is not performed, the pH is high and the alkalinity of the magnesium hydroxide surface is high. As a result, the ester-based resin is hydrolyzed, the handling of the resin composition is lowered, and there is a concern that the original properties (impact resistance, etc.) of the resin are lowered. Moreover, acid resistance is also low.

  The [101] / [001] peak intensity ratio in X-ray diffraction is limited to 0.9 or more. When the [101] / [001] peak intensity ratio in X-ray diffraction is less than 0.9, since the uniform coating with the surface treatment agent is not applied, the pH is high, and the ester resin is hydrolyzed due to the alkalinity of the magnesium hydroxide surface. As a result, the handling of the resin composition is lowered, and there is a concern that the original properties (impact resistance, etc.) of the resin are lowered. Moreover, acid resistance is also low.

  As for the surface treatment, hydrolysis treatment and tracking resistance of the ester resin can be improved if the magnesium hydroxide particles are previously surface treated with an inorganic material obtained by mixing silica and alumina. Furthermore, hardened oil, fatty acid ester, silane coupling agent, silicon oil, phosphate ester on the mixed coating layer of Si compound and Al compound for the purpose of improving acid resistance, workability, mold releasability, etc. The surface treatment may be performed with at least one of a surfactant and a polymer flocculant.

Examples of the hardened oil include beef fat hardened oil and castor hardened oil.
Examples of fatty acid esters include fatty acid esters of higher polyhydric alcohols and higher fatty acid esters. Examples of fatty acid esters of polyhydric alcohols include glycerin-monostearate, glycerin-distearate, glycerin-monooleate, and glycerin-diolate. Examples of higher fatty acid esters include stearic acid, oleic acid, palmitic acid, linoleic acid, lauric acid, capric acid, behenic acid, montanic acid, and other methyl esters, ethyl esters, n-propyl esters, iso-propyl esters, butyl esters, octyls. Examples include esters, lauryl esters, stearyl esters, and behenyl esters.

  Silicon oil includes unmodified silicone oil and modified silicone oil. Examples of the unmodified silicone oil include methylphenyl silicone oil in which part of the side chain of polysiloxane is a phenyl group, and methylhydrogen silicone oil in which part of the side chain of polysiloxane is a hydrogen atom. Examples of the modified silicone oil include alkoxy modification, amino modification, carboxy modification, epoxy modification, silazane modification, phenol modification, carbinol modification, methacryl modification, mercapto modification, polyether modification, methylstyryl modification, alkyl modification, and higher grades. Examples include fatty acid ester modification, fluorine modification, and hydrophilic special modification. The silicone oil can be used alone or in combination of two or more.

  Examples of the silane coupling agent include γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, methacryloxy series such as γ-methacryloxypropyltriethoxysilane, vinyltri Vinyl series such as methoxysilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane , Β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and the like, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N beta (aminoethyl) .gamma.-aminopropyltriethoxysilane, .gamma.-aminopropyltrimethoxysilane, .gamma.-aminopropyltriethoxysilane, there are amino-based, such as N- phenyl--γ- aminopropyltrimethoxysilane. The said silane coupling agent can be used individually by 1 type or in combination of 2 or more types.

  Phosphoric esters include phosphate esters of mono and di-saturated alcohols such as mono-stearyl acid phosphate, di-stearyl acid phosphate, mono-lauryl acid phosphate, di-lauryl acid phosphate, mono-myristyl Acid Phosphate, Di-Myristyl Acid Phosphate, Mono-Palmityl Acid Phosphate, Di-Palmityl Acid Phosphate, Mono-Arakil Acid Phosphate, Di-Arakil Acid Phosphate, Mono-Beher Acid Phosphate , Di-beher acid phosphate, mono-lignoseryl acid phosphate, di-lignoseryl acid phosphate and metal salts thereof (Na, K, Al, Ca, Mg, Zn, Ba), etc., mono and di -Saturated alcohol It may be used one type or a mixture thereof phosphate ester le.

  Examples of the surfactant include sulfate esters of higher alcohols such as anionic stearyl alcohol and oleyl alcohol, sulfate esters of polyethylene glycol ether, amide bond sulfate esters, ester bond sulfate esters, ester bond sulfonates, amides. Examples include bonded sulfonates, ether-bonded sulfonates, ether-bonded alkyl allyl sulfonates, ester-bonded alkyl allyl sulfonates, amide-bonded alkyl allyl sulfonates, and nonionic glycerin fatty acid esters or sorbitan fatty acid esters. It is done.

  Polymer flocculants are roughly classified into three types: nonionic, anionic and cationic. Examples of nonionic polymer flocculants include polyacrylamide. Examples of the anionic polymer flocculant include acrylamide / sodium acrylate copolymer. Examples of the cationic polymer flocculant include a copolymer of acrylamide / dimethylaminoethyl acrylate methyl chloride quaternary salt.

  When the magnesium hydroxide powder of the present invention is blended with an ester resin, excellent flame retardancy is obtained, the ester resin is not hydrolyzed, and the original characteristics of the resin can be utilized. The handling property of the resin composition is not lowered and the acid resistance is also high.

  Although the optimal example for implementing this invention is shown below, this invention is not limited to this.

  A sample powder in which magnesium hydroxide particles were coated with a mixed coating layer of an Si compound and an Al compound was manufactured, and then blended with a resin having an ester bond to examine the hydrolyzability of the resin when it was made into a resin composition. Furthermore, the handling property in the case of molding this resin composition and the flame retardancy and tracking resistance of the molded product were evaluated.

Example 1
Production of sample powder
To an aqueous suspension containing 100 g of magnesium hydroxide having a BET specific surface area of 30 m ² / g and an average particle size of 5.3 μm, 800 g of NaOH flakes were added (OH ⁻ / Mg ²⁺ molar ratio = 11.7), and Pure water was added to adjust the liquid volume to 1.5 L. 1 kg of zirconia balls having a diameter of 3 mm was added thereto, and wet pulverized for 15 minutes at 650 rpm with stirring. Thereafter, zirconia balls were removed from the suspension and poured into a 2 L nickel autoclave, and hydrothermal treatment was performed at 270 ° C. for 10 hours with stirring. The slurry after the hydrothermal treatment was vacuum filtered, and then thoroughly washed with 20 times or more volume of water relative to the solid content. Then, it is emulsified by returning to water again, and at room temperature under stirring, a mixed aqueous solution of sodium aluminate and colloidal silica is added to the solid content by 1% by mass in terms of Al ₂ O ₃ and 1% by mass in terms of SiO ₂ Then, the surface coating treatment was performed for 1 hour. Thereafter, vacuum filtration, washing with water (more than 20 times the solid content), drying and pulverization were performed to obtain a sample powder of magnesium hydroxide powder. The existence form of Si compound or Al compound is mainly SiO ₂ and Al ₂ O ₃ or a hydroxide thereof. Hereinafter, this sample is referred to as Example 1.

Production of Flame Retardant Resin Composition and Molded Body After blending and mixing 100 parts by mass of the sample powder as described above with 100 parts by mass of polylactic acid resin, 180 labs were used using a lab plast mill (manufactured by Toyo Seiki Co., Ltd.). Kneaded at 50 ° C for 5 minutes at a rotation speed of 50rpm, performed die press molding at 150 ° C, and molded product A-1 for combustion test by oxygen index method (length 150mm, width 6.5mm, thickness 3mm) Got. The production conditions for the flame-retardant resin molded body are the same in the following.

Production of tracking-resistant resin composition and molded body
After blending and mixing 30 parts by mass of the above-mentioned sample powder with 100 parts by mass of PBT resin, mixing for 20 minutes with a blender, and then using an injection molding machine at 340 ° C, length 100 mm, width 100 mm, thickness 3 mm A sheet was formed. The manufacturing conditions for the tracking-resistant resin molding are the same in the following.

Analysis / Evaluation Method The sample powder, resin composition, and molded body were analyzed and evaluated as follows. The results are shown in Table 1 for Example 1 and Examples 2 to 10 described later, and the results are shown in Table 2 for each Comparative Example described later.

Measurement of BET specific surface area, average particle diameter and [101] / [001] peak intensity ratio The BET specific surface area of the sample powder was measured by the nitrogen adsorption method, and the particle size distribution was determined by suspending the sample powder in ethanol. The dispersion was treated with ultrasonic waves for 3 minutes and then measured by a laser diffraction method. In addition, the [101] / [001] peak intensity ratio in X-ray diffraction was measured using an X-ray diffractometer (Cu Kα ray, 40 kV, 50 mA) manufactured by Rigaku Corporation, and the peak intensity of [101] (2θ = 38.0 °) and [001] peak intensity (2θ = 18.6 °) was measured.

Evaluation of pH and acid resistance of sample powder The potentiometric titration method was used for the pH and acid resistance test of the sample powder. That is, 1.0 g of the sample powder prepared in Example 1 was added to 100 ml of a 0.1% by mass aqueous solution of polyethylene glycol monolauryl ether (n = 25), stirred for 5 minutes with a stirrer, and then dispersed for 10 minutes with ultrasound. A suspension was prepared. While maintaining this suspension at 25 ° C. in a thermostatic bath and bubbling with N ₂ gas, using an automatic titrator (AT-400, manufactured by Kyoto Electronics Industry Co., Ltd.), 0.1 mol / L nitric acid aqueous solution was added at 0.1 ml / L A titration curve was obtained by dropping dropwise at a rate of min (0.6 mmol / min as hydrogen ions per 1 mol of magnesium hydroxide) and measuring the pH in the titration solution using a glass electrode. The pH before dropping nitric acid means the original pH of the sample powder. The lower the pH, the denser the alkali surface of magnesium hydroxide is coated with the surface treatment agent, resulting in more efficient hydrolysis resistance of the resin. Suppress it. The pH before nitric acid dropping is preferably 7.0 or less. On the other hand, the pH after dropping 10 ml of nitric acid indicates the acid resistance of the powder, and the pH after dropping 10 ml of nitric acid is preferably 3.0 or less because of high acid resistance.

Evaluation of Hydrolyzability of Resin The kneading torque when kneading the polylactic acid resin and the sample powder with a lab plast mill was measured to evaluate the hydrolyzability of the polylactic acid resin. As the hydrolysis proceeds, the kneading torque of the resin composition is lower than the kneading torque of the resin itself, and the resin composition becomes liquid. Specifically, when the torque after 5 minutes from the start of kneading is 19 N · m or more, hydrolysis was not progressed, and when the torque was 19 N · m or less, hydrolysis was progressing and X was marked.

Evaluation of Handling Property of Resin Composition The handling property at the time of molding of a resin composition containing the above-mentioned polylactic acid resin or PBT resin and sample powder was evaluated. In the case where the hydrolysis of the resin has progressed, the resin composition at high temperature becomes liquid, the thixotropy is high, and the handling property is deteriorated. Those with good handling properties were marked with ◯, and those with poor handling properties were marked with ×.

Oxygen Index of Molded Body The oxygen index of the molded body of the polylactic acid resin composition described above was measured according to JISK 7201. A high oxygen index means high flame retardancy. For example, in the above formula, the oxygen index that can pass the UL-94 standard vertical combustion test (V-1) is 38.0 or more. Is preferred.

Tracking Resistance of Molded Body The relative tracking index (CTI value) of the molded body of the PBT resin composition described above was measured according to IEC60112. The CTI value represents the voltage until ignition, and the larger the value, the better the electrical characteristics and the better the insulating property and the less likely to ignite.

Example 2
360 g of MgCl ₂ .6H ₂ O was weighed, 1 L of pure water was added and stirred to prepare an MgCl ₂ aqueous solution. While stirring this MgCl ₂ aqueous solution, 790 g of NaOH flakes were added (OH ⁻ / Mg ²⁺ molar ratio = 11.2), and pure water was further added to prepare a 1.5 L suspension. The suspension was poured into a 2 L nickel autoclave and hydrothermally treated for 10 hours at 250 ° C. with stirring. The slurry after the hydrothermal treatment was vacuum filtered, and then thoroughly washed with 20 times or more volume of water relative to the solid content. Thereafter, the mixture was again emulsified in water, and at room temperature and under stirring, the mixed aqueous solution of alumina sol and sodium silicate was 1% by mass in terms of Al ₂ O ₃ and 1% by mass in terms of SiO _{2 with} respect to the solid content in terms of magnesium hydroxide. A sample powder and a molded body were produced by performing the same operation as in Example 1 except that the surface coating treatment was performed for 1 hour by adding%, and analysis and evaluation were performed.

Example 3
BET specific surface area of 40 m ² / g, an average particle diameter of magnesium oxide 69g of 3.2 .mu.m, the LiOH · H ₂ O was added 400g (OH ^- / Mg ²⁺ molar ratio = 5.6), 1.5 L by adding water The liquid volume was adjusted. 1 kg of zirconia balls having a diameter of 3 mm was added thereto, and wet pulverized for 15 minutes at 650 rpm with stirring. Thereafter, the zirconia balls were removed from the suspension, poured into a 2 L nickel autoclave, and subjected to a hydrothermal hydration reaction at 200 ° C. for 10 hours under stirring, and the same operation as in Example 1 was performed. Sample powders and compacts were manufactured and analyzed and evaluated.

Example 4
After heating the liquid surface-treated with a mixed aqueous solution of sodium aluminate and colloidal silica in Example 1 to 80 ° C., further using a beef tallow oil suspension with a concentration of 1 mass% at a temperature of 80 ° C. A sample powder and a molded body were produced by performing the same operation as in Example 1 except that the surface treatment was performed by adding 1% by mass to the solid content, and analysis and evaluation were performed.

Example 5
The liquid surface-treated with a mixed aqueous solution of sodium aluminate and colloidal silica in Example 1 was heated to 80 ° C., and then a stearic acid monoglyceride aqueous suspension having a concentration of 1 mass% at a temperature of 80 ° C. was used. A sample powder and a molded body were produced by performing the same operations as in Example 1 except that the surface treatment was performed by adding 1% by mass of monoglyceride to the solid content, and analysis and evaluation were performed.

Example 6
The liquid surface-treated with a mixed aqueous solution of sodium aluminate and colloidal silica in Example 1 was heated to 80 ° C., and further, an aqueous solution of sodium monostearyl phosphate and sodium distearyl phosphate having a concentration of 1% by mass at a temperature of 80 ° C. was used. The sample powder and the molded body were manufactured in the same manner as in Example 1 except that the surface treatment was performed by adding 1% by mass of the sodium monostearyl phosphate and sodium distearyl phosphate to the solid content. Analysis and evaluation were performed.

Example 7
In the solution obtained by surface coating with a mixed aqueous solution of sodium aluminate and colloidal silica in Example 1, a γ-methacryloxypropyltrimethoxysilane aqueous solution having a concentration of 1% by mass adjusted to pH = 3 with acetic acid was used. Except for adding 1% by mass of methacryloxypropyltrimethoxysilane to the solid content and performing surface treatment, the same operations as in Example 1 were performed to produce sample powders and compacts, which were then analyzed and evaluated. It was.

Example 8
To the liquid surface-treated with the mixed aqueous solution of sodium aluminate and colloidal silica in Example 1, methyl hydrogen silicone oil was further used, and the surface treatment was performed by adding 1% by mass of methyl hydrogen silicone oil to the solid content. A sample powder and a molded body were produced by performing the same operation as in Example 1 except that the analysis was performed and the evaluation was performed.

Example 9
In the solution obtained by surface coating with a mixed aqueous solution of sodium aluminate and colloidal silica in Example 1, an acrylamide / sodium acrylate copolymer was further used in an amount of 1% by mass with respect to the solid content. A sample powder and a molded body were produced by performing the same operations as in Example 1 except that the surface treatment was performed by adding%, and analysis and evaluation were performed.

Comparative Example 1
BET specific surface area of 40 m ² / g, an average magnesium oxide particle diameter of 3.2 .mu.m 69 g, and 150g added ^{_{LiOH · H 2 O (OH -}} / Mg 2+ molar ratio = 2.1), 1.5 L by adding water The liquid volume was adjusted. 1 kg of zirconia balls having a diameter of 3 mm was added thereto, and wet pulverized for 15 minutes at 650 rpm with stirring. Thereafter, the zirconia balls were removed from the suspension, poured into a 2 L nickel autoclave, and subjected to a hydrothermal hydration reaction at 190 ° C. for 10 hours under stirring. Sample powders and compacts were manufactured and analyzed and evaluated.

Comparative Example 2
100 g of ground natural brucite with a BET specific surface area of 2.5 m ² / g, an average particle size of 13.7 μm, and a [101] / [001] peak intensity ratio of 0.21 in X-ray diffraction is suspended in 1 L of pure water with stirring. did. To this suspension, a mixed aqueous solution of sodium aluminate and colloidal silica was added at 1% by mass in terms of Al ₂ O ₃ and 1% by mass in terms of SiO ₂ with stirring at room temperature for 1 hour. Heat the surface-coated liquid to 80 ° C, and then add 1% by weight of beef fat hardened oil to the solid content at a temperature of 80 ° C using a beef tallow oil suspension with a concentration of 1% by weight. To produce sample powders and compacts for analysis and evaluation.

Comparative Example 3
360 g of MgCl ₂ .6H ₂ O was weighed, 1 L of pure water was added and stirred to prepare an MgCl ₂ aqueous solution. While stirring this MgCl ₂ aqueous solution, 383 mL of 8.3N NaOH aqueous solution was added (OH ⁻ / Mg ²⁺ molar ratio = 1.8), and pure water was further added to prepare a 1.5 L suspension. This suspension was poured into a 2 L nickel autoclave and hydrothermally treated at 140 ° C. for 5 hours with stirring. The slurry after the hydrothermal treatment was vacuum filtered, and then thoroughly washed with 20 times or more volume of water relative to the solid content. Then, it is emulsified by returning to water again, and at room temperature under stirring, a mixed aqueous solution of sodium aluminate and colloidal silica is added to the solid content by 1% by mass in terms of Al ₂ O ₃ and 1% by mass in terms of SiO ₂ 1 hour surface coating treatment, and then using methyl hydrogen silicone oil to add 1% by mass of methyl hydrogen silicone oil to the solid content, surface treatment to produce sample powder and molded body, analysis And evaluated.

Comparative Example 4
A sample powder and a molded body were produced in the same manner as in Example 1 except that the surface coating treatment was not performed, and analysis and evaluation were performed.

Comparative Example 5
Except that the surface coating treatment was not performed with the mixed aqueous solution of sodium aluminate and colloidal silica in Example 5 (surface treatment was performed only with stearic acid monoglyceride), the same operations as in Example 5 were performed to produce sample powders and molded products. Analysis and evaluation.

Comparative Example 6
A sample powder was prepared in the same manner as in Example 9, except that the surface coating was not performed with a mixed aqueous solution of sodium aluminate and colloidal silica in Example 9 (surface treatment was performed only with an acrylamide / sodium acrylate copolymer). And a molded object was manufactured and analyzed and evaluated.

Comparative Example 7
The sample powder of Comparative Example 7 was prepared in the same manner as in Example 1 except that a molded product of the resin composition was produced using a commercially available zinc solid solution type composite magnesium hydroxide (ZnO content: 25% by mass). To produce sample powders and compacts for analysis and evaluation.

Comparative Example 8
The sample powder of Comparative Example 8 was prepared by performing the same operation as in Example 1 except that a molded product of the resin composition was produced using commercially available spherical silica (FB-910 manufactured by Electrochemical Co., Ltd.). Molded bodies were manufactured and analyzed and evaluated.

Claims (6)

Synthetic magnesium hydroxide particles having a BET specific surface area of 0.1 m ² / g or more and less than 1 m ² / g, an average particle diameter of more than 5 μm and 20 μm or less, and a [101] / [001] peak intensity ratio in X-ray diffraction of 0.9 or more , Magnesium hydroxide-based powder in which a mixed coating layer of Si compound and Al compound is formed at a ratio of 0.2 to 10% by mass with respect to 100% by mass of magnesium hydroxide as a total amount in terms of SiO ₂ and Al ₂ O ₃ body. The magnesium hydroxide particles forming the mixed coating layer of the Si compound and the Al compound are further at least one of hardened oil, fatty acid ester, silane coupling agent, silicon oil, phosphate ester, surfactant, and polymer flocculant. The magnesium hydroxide powder according to claim 1, wherein the surface treatment is performed at a ratio of 0.1 to 10% by mass with respect to 100% by mass of magnesium hydroxide. The Si compound is at least one compound selected from the group consisting of sodium silicate, colloidal silica, and precursors thereof, and the Al compound is aluminum chloride, aluminum sulfate, aluminum nitrate, sodium aluminate, alumina sol, and precursors thereof. The magnesium hydroxide-based powder according to claim 1, which is at least one compound of the group consisting of: As a raw material for magnesium hydroxide particles, an aqueous suspension of magnesium hydroxide or magnesium oxide, or an aqueous solution of magnesium chloride, magnesium sulfate or magnesium nitrate,
When the raw material of the magnesium hydroxide particles is an aqueous suspension of magnesium hydroxide or magnesium oxide, wet pulverization is performed by adding lithium hydroxide or sodium hydroxide in a molar ratio of OH ⁻ / Mg ²⁺ of 5 or more. And
When the raw material of the magnesium hydroxide particles is an aqueous solution of magnesium chloride, magnesium sulfate or magnesium nitrate, lithium hydroxide or sodium hydroxide is added in a molar ratio of OH ⁻ / Mg ²⁺ of 5 or more,
In either case, after addition of lithium hydroxide or sodium hydroxide, by hydrothermal treatment at 200-270 ° C,
Synthetic magnesium hydroxide particles having a BET specific surface area of 0.1 m ² / g or more and less than 1 m ² / g, an average particle diameter of more than 5 μm and 20 μm or less, and a [101] / [001] peak intensity ratio in X-ray diffraction of 0.9 or more ,
Surface treatment of the obtained synthetic magnesium hydroxide, mixed coating layer of Si compound and Al compound, 0.2-10 mass with respect to 100 mass% of magnesium hydroxide in the total amount of SiO ₂ and Al ₂ O ₃ conversion The manufacturing method of the magnesium hydroxide type powder formed in the ratio of%. A resin composition comprising 5 to 500 parts by mass of the magnesium hydroxide-based powder according to any one of claims 1 to 3 with respect to 100 parts by mass of a synthetic resin having an ester bond. A molded article of the resin composition according to claim 5.