JPH11349851A - Production of coupling agent-treated inorganic particle and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing coupling agent-treated inorganic particles, wherein the two requirements of the achievment of the uniform surface treatment by a wet treating process and the realization of a high rate of utilization of a coupling agent by a dry treating process are both satisfied, to provide inorganic particles obtained by this process, and to provide a synthetic resin composition containing the above inorganic particles and a synthetic resin and forming a molding having excellent physical properties. SOLUTION: There is provided a process for producing a coupling agent-treated inorganic particles, comprising pouring a coupling agent solution to an aqueous suspension of inorganic particles under agitation, agitating the mixture, and drying the mixture by heating without dewatering by filtration and concentration. In one embodiment, the coupling agent solution is a silane coupling agent or a titanate coupling agent in the form of a concentrate, an aqueous solution, or an alcoholic solution. In another embodiment, the drying is performed by spraying the mixture in the form of fine liquid drops into hot air. In yet another embodiment, the drying is performed by means of a spray drier or paddle drier. In yet another embodiment, the inorganic particles are made of magnesium hydroxide having a BET specific surface area of 15 m<2> /g or below and a mean secondary particle diameter of 2 μm or below and being in the form a hexagonal plate in respect to the shape of a primary crystalline particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a coupling agent-treated inorganic particle suitable for use as an additive or a filler of a synthetic resin, an inorganic particle obtained by the production method, and containing the inorganic particle. The present invention relates to a synthetic resin composition and a molded article obtained from the synthetic resin composition. More specifically, a coupling agent-treated inorganic material that has excellent surface treatment uniformity, a high utilization rate of an expensive coupling agent, and satisfies the principle condition that a bond is formed between the coupling agent and the surface of the inorganic particle. The present invention relates to a method for producing particles, inorganic particles obtained by the production method, and a synthetic resin composition containing the inorganic particles. Further, the present invention relates to a molded article obtained from the synthetic resin composition.

[0002]

2. Description of the Related Art Inorganic particles used as additives and fillers in synthetic resins generally enhance compatibility with polymers, and processability and moldability of the resulting synthetic resin composition or physical properties of molded articles, Surfactant to improve appearance, etc.
The surface is treated with an organic reagent such as a higher fatty acid. There have also been many proposals to mix inorganic particles treated with various coupling agents into a synthetic resin. However, the coupling agent is generally expensive, and the synthetic resin composition containing the coupling agent-treated inorganic particles has poor processability. There was no. Rather, it is mostly used in a so-called integral blend system, in which inorganic particles treated with higher fatty acids are mainly used and a coupling agent is added at the time of kneading as needed.

Recently, there has been a demand for inorganic particles surface-treated with a coupling agent based on the fact that they are not satisfied with the use of the integral blend method and want to extract and use the original performance of the coupling agent. Is coming out.

[0004] As a method for surface-treating inorganic particles with a coupling agent, a dry method is known. For example, while intensely stirring the dry powder of the inorganic particles in the Hensiel mixer, the aqueous solution of the coupling agent is dropped or sprayed and injected using a spray or the like. And is commonly practiced. In this dry method, the entire amount of the aqueous solution of the coupling agent is absorbed by a dry powder of the inorganic particles, and the chemical bond of the coupling agent is formed between the coupling agent and the surface of the inorganic particles by heat dehydration. This is a method that satisfies the processing conditions according to the characteristic. According to this method, the effective utilization rate of the coupling agent used for the treatment is naturally increased to the limit. In this respect, it can be said that the coupling agent is the most suitable surface treatment agent for the dry treatment method.

A method of treating inorganic particles with a coupling agent by a wet surface treatment method has also been proposed. However, the use of an organic solution such as alcohol is a requirement, and there are too many problems to implement for industrial production.

[0006]

When inorganic particles treated with a coupling agent obtained by a conventional dry treatment method are mixed with a synthetic resin, the effect of improving performance as expected is often not obtained. The reason for this is that not only the surface treatment is not uniform in the conventional dry treatment, but also a part of the coupling agent acts as a binder to strongly coagulate the inorganic particles and deteriorate the dispersibility in the resin. It is believed that.
If a uniform surface treatment can be performed, the coupling agent is not localized in the inorganic particles, so that it does not act as a binder, the dispersibility is maintained well, and the effect of the coupling agent treatment is sufficiently exhibited. Becomes That is, it is considered that various physical properties of the synthetic resin composition containing the coupling agent are also improved.

In order to achieve a uniform surface treatment of the coupling agent to the inorganic particles, a wet surface treatment is most preferred. However, after subjecting the inorganic particles to a wet surface treatment with a coupling agent and then filtering and dehydrating as in the case of the conventional higher fatty acid treated product before passing through the drying step, most of the coupling agent used flows out together with the filtrate and causes loss. Not only become
The COD (Chemical Oxygen Demand) in the wastewater is also high, and there is a problem that the wastewater treatment is costly.

The present inventors have studied the elements of the above-mentioned problems, and as a result, have reached the present invention. That is, an object of the present invention is to provide a method for producing a coupling agent-treated inorganic particle which balances two factors, that is, a uniform surface treatment property by a wet treatment method and a high utilization rate of a coupling agent by a dry treatment method, and the production method. The purpose is to provide the obtained inorganic particles.
Another object of the present invention is to provide a synthetic resin composition capable of providing a molded article having excellent physical properties when inorganic particles treated with a coupling agent are blended with the synthetic resin.

[0009]

According to the present invention, a coupling agent solution is poured into an aqueous suspension of inorganic particles under stirring, mixed with stirring, and then heated and dried without filtration, dehydration and concentration. Provided are a method for producing inorganic particles treated with a coupling agent, inorganic particles obtained by the method, a synthetic resin composition containing the inorganic particles, and a molded article obtained from the synthetic resin composition.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The inorganic particles used in the production method of the present invention include metal compounds such as hydroxides, carbonates, basic carbonates, basic sulfates, phosphates, silicates and oxides. It is. Next, metal compounds suitable for use in the present invention will be specifically exemplified. Aluminum hydroxide, magnesium hydroxide, solid solution hydroxide: Mg _1-x M _x (OH) _{2 wherein}
M is a divalent metal such as Mn, Co, Fe, Ni, Zn, etc., x <
Indicate the number of 1], hydrotalcite compound, LiA
l ₂ (OH) _{6 An} ^- _{1 / n} · mH ₂ O [wherein, A is an n-valent anion, m> 3], charcoal alumite type compound, magnesium carbonate, calcium carbonate, basic carbonate Calcium, dawsonite, basic magnesium sulfate: M
g ₆ (OH) ₁₀ SO ₄ .3H ₂ O, calcium phosphate, talc, mica, kaolin, alumina, titania, magnesia, zinc white, and spinel type oxide [MgAl ₂ O ₄ ,
ZnAl ₂ O ₄ ] and the like. The production method of the present invention relates to magnesium hydroxide, preferably BE, which is useful as a flame retardant for synthetic resins.
It is useful as an additive such as magnesium hydroxide having a T specific surface area of 15 m ² / g or less, an average secondary particle diameter of 2 μm or less, and more preferably hexagonal plate-like primary crystal particles, or a stabilizer for a synthetic resin. It is suitable for surface treatment of inorganic particles such as hydrotalcite compounds, preferably hydrotalcite compounds having a BET specific surface area of 40 m ² / g or less and an average secondary particle diameter of 4 μm or less.

The BET specific surface area was determined by measuring the adsorption of nitrogen at the nitrogen boiling point and applying the BET equation with the area occupied by nitrogen adsorption being 16.2 °. The average secondary particle diameter was determined by measuring the particle size distribution by a laser light diffraction scattering method. The shape of the primary crystal grains was observed by a scanning electron microscope (SEM) photograph at a magnification of about 10,000.

The concentration of the aqueous suspension of the inorganic particles used in the present invention must be low, especially when the viscosity is high, but the higher the concentration, the higher the concentration of the aqueous solution. Good. The concentration that can be used is 0.
It is 1% by weight to 40% by weight. However, from the viewpoints of productivity and economy, the range is preferably 5 to 30% by weight, more preferably 10 to 25% by weight. In the spray drying, the suspension of the surface-treated inorganic particles may be atomized by any method, and examples thereof include a rotary atomizer method, a nozzle spray method, and a disk spray method. The size of the fine droplet is about 50 to 1200 μm in diameter.
m is preferable, and the range of 100 to 600 μm is more preferable. If the droplets are larger than this range, the falling speed becomes faster, the time in the hot air becomes shorter, the drying time tends to be insufficient, and the obtained product tends to be insufficiently dried. The preferable drying time, that is, the residence time in hot air is generally several seconds to several tens of seconds. If the size of the droplets is smaller than the above range, the particles become fine particles and have a poor flow, resulting in poor workability. Hot air temperature is about 100-600 ° C
And more preferably in the range of 120 to 500 ° C. At a temperature lower than this range, drying tends to be insufficient, and at a high temperature, the product may be thermally decomposed,
Not desirable.

The coupling agents used in the present invention are various silane coupling agents and titanate coupling agents. Next, these will be specifically exemplified.

Vinyl silane compounds such as vinyl ethoxysilane, vinyl trimethoxy silane, vinyl tris (β-methoxyethoxy) silane, γ-methacryloxypropyl trimethoxy lan, γ-aminopropyl trimethoxy lan, Ν-β- Amino-based silane compounds such as (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropylmethyldimethoxysilane, and γ-ureidopropyltriethoxysilane;
γ-glycidoxypropyltrimethoxysilane, β-
Epoxy silane compounds such as (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, mercapto silane compounds such as γ-mercaptopropyltrimethoxysilane, Ν-phenyl-γ- Phenylamino silane compounds such as aminopropyltrimethoxysilane;

Isopropyl triisostearoylated titanate, tetraoctyl bis (ditridecyl phosphite) titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, isopropyl tridodecyl benzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (Dioctyl phosphite) titanate, tetra (1,1-diallyloxymethyl-1-)
Butyl) bis- (ditridecyl) phosphite titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyltrioctanoyl titanate,
Isopropyl dimethacrylisostearoyl titanate, isopropyl tristearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate,
Titanate compounds such as dicumylphenyloxyacetate titanate and diisostearoylethylene titanate;

The amount of the coupling agent used in the surface treatment is preferably in the range of 0.01 to 3% by weight, more preferably 0.05 to 2% by weight, based on the inorganic particles. When the amount of the coupling agent to be used is out of the above range, inorganic particles capable of providing a practical synthetic resin composition or molded article with a balance in mechanical properties and chemical properties cannot be obtained.

The coupling agent solution used for the surface treatment of the present invention may be used as it is, but may be used in the form of water and / or water.
Alternatively, it may be used after being diluted with alcohols, or may be used in water and / or alcohol solution adjusted to pH by adding an acid. Further, as a method of adding the coupling agent solution, no special means such as spraying using a spray or the like is required, and it is sufficient to simply pour a predetermined amount accurately into the suspension of the inorganic particles. Stirring after pouring may be such that it can be uniformly mixed within a predetermined time, and a particularly strong stirring force is not required.

In the production method of the present invention, the aqueous suspension of the inorganic particles after the wet-process surface treatment is dried substantially without filtration, dehydration or concentration by a reduced pressure filter or a pressure filter, or the like. This is a method for producing inorganic particles treated with a coupling agent by drying using a spray drier or a paddle drier. In a conventional manufacturing method that does not use a spray drier or a paddle drier, it is necessary to carry out filtration dehydration before drying. At this time, the coupling agent moves into the filtrate and is lost. In addition, since the cake after dehydration has a thixotropic viscoelasticity, there are problems such as difficulty in detaching from the filter cloth and inability to shred the cake. It was difficult or almost impossible to work. The manufacturing method of the present invention is a manufacturing method capable of avoiding many problems as described above.

In the present invention, synthetic resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer. Coalesce, ethylene-propylene copolymer, propylene homopolymer, ethylene-propylene rubber, ethylene-propylene-diene rubber, polybutene,
Polyolefins such as butyl rubber, polypropylene-based thermoplastic elastomers, polyethylene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers such as polystyrene-based thermoplastic elastomers, bisphenol A epoxy resin, cresol novolac epoxy resin,
Phenol novolak type epoxy resin, biphenyl type epoxy resin, naphthalene ring-containing epoxy resin, allylphenol novolak type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin and epoxy resins such as halides thereof, polyamide 6, polyamide 66 , Polyamide 610, polyamide 12, polyamide 46 and other polyamide resins, polyurethane, HIPS, PS, AB
It means a synthetic resin such as S and polyester.

When the coupling agent-treated inorganic substance obtained by the production method of the present invention is applied to a synthetic resin composition as an additive, a filler, or the like, the type of the coupling agent and the type of the synthetic resin can be appropriately selected. The present invention provides a resin composition having excellent mechanical and chemical properties, which cannot be obtained with a conventional fatty acid-treated product, and a molded product from the resin composition. For example, EVA (ethylene / vinyl acetate copolymer) and EEA (ethylene / ethyl acrylate copolymer) treated with aminosilane-based coupling agent, TPO (polyolefin-based thermoplastic elastomer)
When aminosilane-based or mercaptosilane-based coupling agent-treated inorganic particles are used for the base resin, both tensile strength and elongation maintain high values. In addition, the use of epoxysilane-based or aminosilane-based coupling agent-treated inorganic particles with epoxy resin improves the physical properties of the cured product without delaying the curing reaction, and makes the epoxy resin composition excellent in water absorption resistance and thermal shock resistance. Things are provided.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0022]

Examples 1 to 5 and Comparative Examples 1 and 2 The average secondary particle diameter was 0.
A 150 g / L aqueous suspension was prepared at a Mg (OH) ₂ concentration of 58 μm using a magnesium hydroxide having a BET comparison area of 6.5 m ² / g. A 5% by weight aqueous solution of γ-aminopropyltrietoxin silane was prepared, and the respective addition amounts shown in Table 1 were poured into a magnesium hydroxide suspension aqueous solution with stirring, stirred for 30 minutes, and then led to a spray drier. And dried.

In Comparative Example 1, 1.5 kg of the dry powder of magnesium hydroxide used in Example 1 was placed in a Henschel mixer having a capacity of 20 L, and 150 mL of a 5% by weight aqueous solution of γ-aminopropyltrietoxin silane was added.
The dry powder was added with high speed stirring. In the meantime, the operation of stopping the stirring, scraping off the deposits on the inner wall and the stirring wall and restarting the stirring was repeated three times. After the treatment, the mixture was heated to 100 ° C., dried, and pulverized. Comparative Example 2
Was subjected to a wet treatment in the same manner as in Example 1, then dehydrated with a press filter and then dried and pulverized. Table 1 shows the analysis value (shown in the column of adsorption amount) of the treating agent content of the obtained magnesium hydroxide treated with γ-aminopropyltrietoxin silane and the measured value of the average particle size.

Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Addition amount (wt%) 0.3 0.4 0.5 0.6 1.0 0.5 1.0 Adsorption amount (wt%) 0.20 0.29 0.39 0.40 0.63 0.30 0.1 Utilization rate (%) 66 72 70 67 63 60 10 Average secondary particle diameter (μm) 0.55 0.58 0.58 0.58 0.60 0.70 0.58 (1) Adsorption amount: Treating agent molecule based on Si content obtained by X-ray fluorescence analysis (2) Effective utilization rate (%) = (adsorption amount / addition amount) × 10
0 As is evident from the results shown in Table 1, in the wet surface treatment with an aqueous solution-spray dryer drying method, the effective utilization rate is better in the case of this aminosilane-based treatment agent than in the case of the dry treatment using a Henschel mixer. Has become. The average particle size in the case of dry processing is 0.70 μm.
m is much larger than the original magnesium hydroxide used, 0.58 μm, indicating that strong aggregation has occurred in part. On the other hand, in the case of wet processing, it is understood that the dispersibility is excellent.

[0025]

Examples 6 to 9 and Comparative Examples 3 and 4 The average secondary particle diameter was 0.1.
A magnesium hydroxide having a BET comparison area of 7.2 m ² / g and a surface treatment agent solution of 52 μm was used. A 5% by weight aqueous solution of vinylethoxysilane adjusted to pH 3.5 to 4.0 by adding an acid was used. Except for the above, the same operation as in Example 1 was performed to obtain a coupling agent-treated magnesium hydroxide.

In Comparative Example 3, a dry treatment was carried out using a Hensiel mixer in the same manner as in Comparative Example 1 except that the magnesium hydroxide used, the treating agent and the amounts added were the same as in Example 8. Comparative Example 4 was operated in the same manner until the same wet treatment as in Example 8 was performed, and after the treatment, filtration, dehydration, drying, and pulverization were performed as in Comparative Example 2. Table 2 shows the results.

Table 2 Example 6 Example 7 Example 8 Example 9 Comparative Example 3 Comparative Example 4 Addition amount (wt%) 0.4 0.7 1.0 1.5 1.0 1.0 Adsorption amount (wt%) 0.10 0.41 0.57 0.92 0.55 0.09 Utilization rate ( %) 25 58 57 61 55 9 Average secondary particle size (μm) 0.50 0.52 0.52 0.53 0.70 0.52

[0028]

Examples 10 and 11 and Comparative Example 5 The average secondary particle diameter was 0.1.
5% by weight aqueous solution of γ-glycidoxypropyltrimethoxysilane as a surface treating agent solution using magnesium hydroxide having a BET specific surface area of 66 m ² / g of 6.2 m ² / g (after being sufficiently dissolved by stirring for 15 minutes or more) Used for surface treatment)
The same operation as in Example 1 was performed except for using, to obtain a coupling agent-treated magnesium hydroxide. In Comparative Example 5, wet surface treatment was performed in the same manner as in Example 10,
Then, the same operation as in Comparative Example 2 was performed. Table 3 shows the results
Shown in Table 3 Example 10 Example 11 Comparative Example 5 Addition amount (wt%) 1.0 0.3 1.0 Adsorption amount (wt%) 0.85 0.24 0.12 Utilization rate (%) 85 80 12

[0029]

Example 12, Comparative Examples 6 and 7 100 parts by weight of an ethylene-ethyl acrylate copolymer (EEA: "NUC830") and maleic anhydride-modified polyethylene (Nippon Petrochemical Co., Ltd.)
1 part by weight of an antioxidant (“Irganox1010” manufactured by Ciba-Geigy) and 20 parts by weight of each sample (sample obtained in Example 3 and Comparative Example 1, magnesium stearate-treated magnesium hydroxide) (Fatty acid-treated product)) After mixing 150 parts by weight, the mixture was kneaded at 190 ° C with a single screw extruder to obtain pellets. This pellet was vacuum-dried at 50 ° C. for 16 hours, and then pressed twice at 190 ° C. for 5 minutes using a press molding machine. A dumbbell-shaped test piece was punched out of the obtained sheet, and a test for measuring each characteristic value was performed. It was a piece.

Table 4 Example 12 Comparative Example 6 Comparative Example 7 MI (g / 10min) 0.21 0.14 0.34 MFR (g / 10min) 30 20 39.4 Yield Point Tensile Strength (kgf / mm ²⁾ ) 0.70 0.65 0.60 Tensile strength at break (kgf / mm ² ) 1.15 0.95 0.90 Elongation (%) 630 510 640 Sample Example 3 Comparative Example 1 Stearic acid treatment Cup according to the present invention The ring agent-treated product is superior to the fatty acid-treated product and the dry coupling agent-treated product in mechanical properties, and is also superior in workability to the dry-processed product.

[0031]

Examples 13 to 16 and Comparative Examples 8 to 9 Using an average secondary particle diameter of 0.60 μm, a BET specific surface area of 6.8 m ² / g magnesium hydroxide, and adding an acid as a surface treatment solution to pH
A 5 wt% aqueous solution of γ-methacryloxypropyltrimethoxysilane adjusted to 3.5 to 4.0 was used, and the operation was performed in the same manner as in Example 1 except that the addition amount was changed as shown in Table 5. A magnesium hydroxide treated with a coupling agent was obtained. Comparative Example 8 was performed in the same manner as in Comparative Example 1 except that magnesium hydroxide, the treatment solution, and the amount added were the same as those in Example 16.
Dry processing was performed using a Henschel mixer in the same manner as in the above. In Comparative Example 9, magnesium hydroxide, a treatment solution and the amount of addition thereof were the same as in Example 15, and the same operation as in Example 1 was performed until the wet treatment, and then filtration, dehydration, drying, and pulverization were performed in the same manner as in Comparative Example 2. went. Table 5 shows the test results.

Table 5 Example 13 Example 14 Example 15 Example 16 Comparative Example 8 Comparative Example 9 Addition amount (wt%) 0.3 0.5 1.0 1.5 1.5 1.0 Adsorption amount (wt%) 0.22 0.35 0.74 1.03 1.05 0.1 %) 73 70 74 69 70 10 Average secondary particle size (μm) 0.62 0.65 0.68 0.69 0.97 0.62

[0033]

Example 17, Comparative Examples 10 and 11 100 parts by weight of an ethylene-vinyl acetate copolymer (EVA: RB-11), 1 part by weight of an antioxidant (Irganox 1010) and a crosslinking agent (DC)
P) 0.5 part by weight of each sample (200 parts by weight of each of the coupling agent-treated magnesium hydroxide obtained in Example 16 and Comparative Example 8 and the magnesium hydroxide used in Comparative Example 7) was mixed. The mixture was kneaded at 100 ° C. with a screw extruder to obtain pellets. The pellet was vacuum-dried at 50 ° C. for 16 hours, and then cross-linked at 180 ° C., and a dumbbell-shaped test piece was punched from the obtained sheet to obtain a test piece for measurement. Table 6 shows the results.

Table 6 Example 17 Comparative Example 10 Comparative Example 11 Tensile strength at yield point (kgf / mm ² ) 1.33 0.95 0.82 Elongation at break (%) 230 180 250 Sample Example 16 Comparative Example 8 Stearic acid treatment

[0035]

According to the present invention, there is provided a method for producing inorganic particles having a high utilization of a coupling agent, enabling uniform surface treatment and control to a target treatment amount, inorganic particles obtained by the method, There is provided a synthetic resin composition which can provide a molded article containing the inorganic particles and having excellent mechanical properties, workability, and appearance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 9/06 C08K 9/06 C08L 23/00 C08L 23/00 63/00 63/00 C 101/00 101/00

Claims (13)

[Claims] 1. A coupling agent-treated inorganic particle, wherein a coupling agent solution is poured into an aqueous suspension of inorganic particles under stirring, and the mixture is stirred and mixed, and then heated and dried without filtration, dehydration and concentration. Manufacturing method. 2. The method according to claim 1, wherein the coupling agent solution is a stock solution, an aqueous solution, or an alcohol solution of a silane coupling agent or a titanate coupling agent.
The manufacturing method as described. 3. The method according to claim 1, wherein the drying is performed by spraying fine droplets in hot air. 4. The method according to claim 1, wherein the drying is performed using a spray drier or a paddle drier. 5. The method according to claim 1, wherein the inorganic particles have a BET specific surface area of 15 m ² /
g or less, average secondary particle diameter of 2 μm or less, magnesium hydroxide having a primary crystal particle shape of a hexagonal plate, or BET
^{2. The} method according to claim 1, wherein the hydrotalcite compound has a specific surface area of 40 m ² / g or less and an average secondary particle diameter of 4 μm or less. 6. 100 parts by weight of a synthetic resin and 1 to 1 parts of the inorganic particles treated with a coupling agent obtained by the production method according to claim 1.
And 300 parts by weight. 7. The inorganic particles having a BET specific surface area of 15 m ² /
g or less, average secondary particle diameter of 2 μm or less, magnesium hydroxide having a primary crystal particle shape of a hexagonal plate, or BET
7. The synthetic resin composition according to claim 6, which is a hydrotalcite compound having a specific surface area of 40 m ² / g or less and an average secondary particle diameter of 4 μm or less. 8. The method according to claim 6, wherein the synthetic resin is a polyolefin resin, and the inorganic particles treated with a coupling agent are magnesium hydroxide treated with a methacryloxy, vinyl or amino silane coupling agent. Synthetic resin composition. 9. The method according to claim 6, wherein the synthetic resin is an epoxy resin and the coupling agent-treated inorganic particles are an epoxy-based or amino-based silane coupling agent-treated hydrotalcite compound or magnesium hydroxide. Synthetic resin composition. 10. A molded article obtained from the synthetic resin composition according to claim 6. 11. The inorganic particles are at least one selected from the group consisting of metal hydroxides, carbonates, basic carbonates, basic sulfates, phosphates, silicates and oxides. Item 6. Coupling agent-treated inorganic particles obtained by the production method according to Item 1. 12. The inorganic particles have a BET specific surface area of 15 m.
² / g or less, average secondary particle diameter of 2 μm or less, coupling agent-treated inorganic particles obtained by the production method according to claim 1, wherein the primary crystal particles are hexagonal plate-shaped magnesium hydroxide. 13. The inorganic particles have a BET specific surface area of 40 m.
^2. Coupling agent-treated inorganic particles obtained by the production method according to claim 1, wherein the particles are hydrotalcite compounds having an average secondary particle diameter of 4 μm or less.