JP2020040859A - Magnesium hydroxide particles and method for producing the same - Google Patents

Abstract

To provide magnesium hydroxide particles with their fluidity and mechanical properties not lowering even after being combined with a resin, a method for producing the same, a resin composition comprising the magnesium hydroxide particles, and a molded article comprising the resin composition.SOLUTION: Magnesium hydroxide particles according to the present invention have a BET specific surface area of less than 0.5 m/g and an average particle diameter of 10 μm or more. In a method for producing the magnesium hydroxide particles according to the present invention, an alkali metal hydroxide is added to a suspension containing magnesium hydroxide so as to represent more than 800 parts by mass based on 100 parts by mass of solid contents of the magnesium hydroxide, and which is followed by hydrothermal treatment at more than 230°C.SELECTED DRAWING: Figure 2

Description

  The present invention relates to magnesium hydroxide particles and a method for producing the same, a resin composition containing the magnesium hydroxide particles, and a molded product containing the resin composition.

  BACKGROUND ART Metal hydroxides such as aluminum hydroxide and magnesium hydroxide are non-toxic inorganic substances and contain no halogen and are environmentally friendly, and thus have been widely used in various fields. For example, metal hydroxides such as aluminum hydroxide and magnesium hydroxide are used in a wide range of fields such as automobile vehicles, railway vehicles, ships, aircraft, industrial equipment, electronic devices, electronic components, insulated wires, optical fiber cables, etc. , Additives, resin fillers, highly functional materials, and catalysts.

  Aluminum hydroxide is an inorganic material having excellent acid resistance, but its decomposition temperature is low, decomposition starts at about 180 ° C, and about 80% of the crystal structure of water is released by 300 ° C. For example, when aluminum hydroxide is molded using a thermoplastic resin as a resin additive, there is a problem that a foaming phenomenon occurs at a temperature of about 200 ° C. or more, and the mechanical strength of the molded body is reduced.

On the other hand, magnesium hydroxide starts to decompose at about 300 ° C., so that it can withstand high processing temperatures. For example, Patent Document 1 discloses that by using magnesium hydroxide having a BET specific surface area of 1 to 25 m ² / g and an average particle diameter of 5 to 500 μm, magnesium hydroxide having good sphericity and high density can be obtained. It states that it can be provided. Further, Patent Document 1 describes that magnesium hydroxide is produced by reacting a water-soluble magnesium salt with ammonia under specific conditions.

JP-A-3-29004

  However, according to the study of the present inventors, magnesium hydroxide described in Patent Document 1 has a large BET specific surface area and a structure in which primary particles are aggregated. And reduced the mechanical properties, and there was room for further improvement.

  Therefore, an object of the present invention is to provide magnesium hydroxide particles and a method for producing the same, which do not cause a decrease in fluidity or mechanical properties even after being combined with a resin, and a resin composition containing the magnesium hydroxide particles and the resin composition. An object of the present invention is to provide a molded article including a product.

  As a result of intensive studies, the present inventors have found that the above-described problems can be solved by adopting the following configuration, and have completed the present invention.

That is, the magnesium hydroxide particles of the present invention have a BET specific surface area of less than 0.5 m ² / g and an average particle diameter of 10 μm or more. Various physical property values in the present invention are values measured by the methods adopted in the examples.

Since the magnesium oxide particles of the present invention have a BET specific surface area of less than 0.5 m ² / g and an average particle diameter of 10 μm or more, even after the magnesium oxide particles of the present invention are combined with a resin, their fluidity and mechanical properties are high. It is possible to prevent the characteristics from deteriorating. Although this mechanism is not clear, it is considered as follows. By controlling the average particle size of the magnesium hydroxide particles to 10 μm or more, the strength of the particles as a structure increases, and it is estimated that the fluidity and mechanical properties such as resin filling property and melt flow rate can be improved. Is done. Further, by controlling the BET specific surface area of the magnesium hydroxide particles to be less than 0.5 m ² / g, the contact area with the resin or the like becomes small when blended with the resin or the like. It is presumed that the fluidity such as the rate and the mechanical properties are easily improved, and the effects of the present invention are more easily obtained.

  In the magnesium hydroxide particles of the present invention, the ratio ([001] / [110]) of the half width of the diffraction peak derived from the [001] plane and the [110] plane in X-ray diffraction is 0.75 or more and less than 1.15. It is preferred that As a result, the obtained magnesium hydroxide particles do not grow crystals in a deviated direction, so that the filling property to the resin, the fluidity such as the melt flow rate, and the mechanical properties are improved.

  The magnesium hydroxide particles of the present invention are composed of higher fatty acids, higher fatty acid alkaline earth metal salts, coupling agents, esters composed of fatty acids and polyhydric alcohols, and phosphate esters composed of phosphoric acid and higher alcohols. Magnesium hydroxide particles that have been surface-treated with at least one surface treatment agent selected from the group are preferred. Thereby, the degree of dispersion of the magnesium hydroxide particles in the organic polymer material (in the molded product) can be further improved.

  The present invention also includes a resin composition in which the magnesium hydroxide particles are mixed in an amount of 5 to 500 parts by mass with respect to 100 parts by mass of the resin. Thereby, since the resin composition of the present invention contains magnesium hydroxide particles having good fluidity and mechanical properties such as filling property and melt flow rate into the resin, excellent fluidity and mechanical properties are provided. In addition to exerting the desired properties, it is possible to suppress a decrease in the physical properties of a molded article obtained therefrom and to secure desired properties.

  In the resin composition of the present invention, the resin is preferably a thermoplastic resin. Thereby, the effect of the present invention can be more reliably obtained without impairing the characteristics of the resin.

  Furthermore, the present invention also includes a molded article containing the resin composition.

  In the method for producing magnesium hydroxide particles of the present invention, an alkali metal hydroxide is added to a suspension containing magnesium hydroxide so as to be more than 800 parts by mass relative to 100 parts by mass of solid magnesium hydroxide. A hydrothermal treatment at a temperature higher than 230 ° C. By producing magnesium hydroxide particles under severe conditions in which the amount of the alkali metal hydroxide added is large and the temperature during the hydrothermal treatment is high, the crystal growth of the primary particles of the obtained magnesium hydroxide particles is promoted. Therefore, since the particle size tends to be large, it is possible to prevent the fluidity and the mechanical properties from decreasing even after the obtained magnesium oxide particles are combined with the resin.

In the present invention, the method for producing magnesium hydroxide particles may include a magnesium hydroxide particle having a BET specific surface area of less than 0.5 m ² / g and an average particle diameter of 10 μm or more in the magnesium hydroxide. preferable. By using particles having a large particle size, magnesium hydroxide particles having a large particle size can be efficiently produced, so that magnesium hydroxide particles having good fluidity and good mechanical properties can be produced more reliably.

  In the present invention, the magnesium hydroxide particles obtained above are used as seed particles, and the seed particles are added to a suspension containing magnesium hydroxide so as to be 5% by mass or more of the solid content of magnesium hydroxide. It is preferable that the method is a method for producing magnesium hydroxide particles in which a metal hydroxide is added so as to be more than 800 parts by mass with respect to 100 parts by mass of magnesium hydroxide solid content and subjected to hydrothermal treatment at more than 230 ° C. By using seed particles having a large particle size, magnesium hydroxide particles having a large particle size can be efficiently produced, so that the fluidity and mechanical properties such as resin filling property and melt flow rate are more reliable. Magnesium hydroxide particles can be produced.

3 is a photograph of a scanning electron microscope (FESEM) showing the magnesium hydroxide particles obtained in Example 1. 6 is a scanning electron microscope (FESEM) photograph showing the magnesium hydroxide particles obtained in Example 3. 4 is a photograph of a scanning electron microscope (FESEM) showing the magnesium hydroxide particles obtained in Comparative Example 1.

[Magnesium hydroxide particles]
The magnesium hydroxide particles in the present invention are composed of powder containing magnesium hydroxide as a main component. The ratio of magnesium hydroxide as a main component is preferably 95% or more, more preferably 98% or more, and 99% or more. % Or more is more preferable. Note that an impurity component derived from a raw material can be included. Magnesium hydroxide is inexpensive, chemically stable, basic, non-toxic, does not burn itself, absorbs heat when decomposed, and decomposes to reduce heat capacity. By releasing large water molecules, it has excellent properties in applications such as non-halogen flame retardants, tracking resistant agents, additives, resin fillers, highly functional materials, and catalysts.

The magnesium hydroxide particles of the present invention have a BET specific surface area of less than 0.5 m ² / g, preferably 0.48 m ² / g or less, more preferably 0.48 m ² / g, from the viewpoint of improving fluidity and mechanical properties. 0.3 m ² / g or less. The lower limit of the BET specific surface area of the magnesium hydroxide particles of the present invention is not particularly limited from the viewpoint that the effects of the present invention are not impaired, but is preferably 0.01 m ² / g or more from the viewpoint of practicality, 0.03m more preferably at least ² / g, more preferably not less than 0.05 m ² / g. Further, BET specific surface area of magnesium hydroxide particles of the present invention, from the viewpoint of improving the fluidity and mechanical characteristics, is preferably less than 0.01 m ² / g or more ^{0.5m 2 / g, 0.03m 2 /} g or 0.48m or less, more preferably ² / g, more preferably 0.05 m ² / g or more 0.3 m ² / g or less.

  The average particle diameter of the magnesium hydroxide particles of the present invention is 10 μm or more, preferably 11 μm or more, and more preferably 12 μm or more, from the viewpoint of improving the fluidity and mechanical properties. The upper limit of the average particle diameter of the magnesium hydroxide particles of the present invention is not particularly limited from the viewpoint that the effects of the present invention are not impaired, but from the viewpoint of practicality, is preferably 200 μm or less, more preferably 100 μm or less. , 80 μm or less. In addition, the average particle size of the magnesium hydroxide particles of the present invention is preferably from 10 μm to 200 μm, more preferably from 11 μm to 100 μm, even more preferably from 12 μm to 80 μm, from the viewpoint of improving the fluidity and mechanical properties.

  In the magnesium hydroxide particles of the present invention, from the viewpoint of reducing the deviation in the direction of crystal growth, the ratio of the half width of the diffraction peak derived from the [001] plane and the [110] plane in X-ray diffraction ([001] / [ 110]) is preferably 0.75 or more and less than 1.15, and more preferably 0.80 or more and 1.14 or less. Further, in the magnesium hydroxide particles of the present invention, the half width of the diffraction peak of [001] (2θ = 18.6 °) in X-ray diffraction is preferably 0.30 ° or less from the viewpoint of increasing the crystallinity, 0.25 degrees or less are more preferable, and 0.20 degrees or less are still more preferable. In addition, from the same viewpoint, the half width of the diffraction peak of [110] (2θ = 58.6 °) in X-ray diffraction is preferably 0.30 ° or less, and more preferably 0.20 ° from the viewpoint of increasing the crystallinity. The following is more preferable, and 0.18 degrees or less is still more preferable. The lower limit of the half width of the [001] diffraction peak (2θ = 18.6 °) in the X-ray diffraction of the magnesium hydroxide particles of the present invention, and the [110] diffraction peak (2θ = 58. The lower limit of the half-value width of 6 °) is not particularly limited from the viewpoint that the effect of the present invention is not impaired, but is preferably 0.01 ° or more and 0.05 ° or more, respectively, from the viewpoint of practicality. Is more preferable, and more preferably 0.07 degrees or more.

  Further, the shape of the magnesium hydroxide particles of the present invention may be such that the primary particles or the secondary particles have a flat plate shape, an irregular shape, or a needle shape, but from the viewpoint of improving fluidity and mechanical properties. The primary particles preferably have a flat or irregular shape, and more preferably a flat shape. The flat plate may be slightly deformed such as a rounded apex as long as it is a substantially flat three-dimensional shape, but is preferably a hexagonal flat plate shape.

  The magnesium hydroxide particles of the present invention do not necessarily have to have a purity of 100%, and may contain impurities depending on the production method and the like. For example, it is a compound of a metal such as iron, copper, manganese, chromium, cobalt, nickel, and vanadium. The content of these impurities is desirably 0.1% by mass or less in particles in terms of metal.

  The magnesium hydroxide particles of the present invention may be surface-treated products that have been surface-treated by using a surface-treating agent or the like. As the surface treatment agent, a known compound used for the purpose can be used. The surface treatment is selected from the group consisting of higher fatty acids, higher fatty acid alkaline earth metal salts, coupling agents, esters composed of fatty acids and polyhydric alcohols, and phosphate esters composed of phosphoric acid and higher alcohols. It is preferable to use at least one of them. By performing the surface treatment, it is possible to improve the dispersibility of the magnesium hydroxide particles in the resin (or in the molded article), and thereby maintain or improve the physical properties of the resin composition and the molded article. Among them, it is preferable to use a coupling agent such as a silane coupling agent from the viewpoint of improving tensile strength. In addition, a surfactant can be used as a surface treatment agent.

  Examples of the coupling agent include γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane Γ-acryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, p-trimethoxysilylstyrene, p-triethoxysilylstyrene, p-trimethoxysilyl-α-methylstyrene, p-triethoxysilyl -Α-methylstyrene 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyl Limethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-propyl-3-amino Silane coupling agents such as propyltrimethoxysilane, 4-aminobutyltrimethoxysilane, decyltrimethoxysilane, isopropyltriisostearoyl titanate, isopropyltris (dioctyl pyrophosphate) titanate, isopropyltri (N-aminoethyl-amino) Titanate-based coupling agents such as ethyl) titanate and isopropyltridecylbenzenesulfonyltitanate; and aluminum-based coupling agents such as acetoalkoxyaluminum diisopropylate. It is below. Such coupling agents may be used alone or in combination of two or more.

  Examples of the higher fatty acids include higher fatty acids having 10 or more carbon atoms, such as stearic acid, erucic acid, palmitic acid, lauric acid, and behenic acid, and stearic acid is preferable in terms of dispersibility and handling properties. Examples of the alkali metal salts of higher fatty acids include the above-mentioned alkali metal salts of higher fatty acids. As the alkali metal, lithium, sodium, potassium and the like can be suitably used. From the viewpoint of dispersibility, alkali metal salts of higher fatty acids are preferable, and among them, sodium stearate is more preferable. These may be used alone or in combination of two or more.

  Examples of esters composed of a fatty acid and a polyhydric alcohol include esters of a fatty acid with a polyhydric alcohol such as glycerin monostearate and glycerin monooleate.

  Phosphoric acid esters composed of phosphoric acid and higher alcohols include, for example, mono- or diesters of orthophosphoric acid and oleyl alcohol, stearyl alcohol and the like, or a mixture of both, and their acid forms or alkali metal salts or amine salts. And the like.

  As the surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be suitably used.

  Examples of the anionic surfactant include alkyl sulfate salts such as sodium lauryl sulfate, higher alcohol sodium sulfate and triethanolamine lauryl sulfate; alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate; alkylnaphthalenes such as sodium alkylnaphthalenesulfonate. Sulfonates; alkyl sulfosuccinates such as sodium dialkyl sulfosuccinate; alkyl diphenyl ether disulfonates such as sodium alkyl diphenyl ether disulfonate; alkyl phosphates such as potassium alkyl phosphate; sodium polyoxyethylene lauryl ether sulfate , Polyoxyethylene alkyl ether sodium sulfate, polyoxyethylene alkyl ether triethanolamine sulfate, polyoxyethylene Ruki Ruch enyl ether polyoxyethylene alkyl (or alkyl aryl), such as sodium sulfate and the like sulfuric ester salts and the like.

  Examples of the cationic surfactant and the amphoteric surfactant include alkylamine salts such as coconutamine acetate and stearylamine acetate; lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyldimethylammonium chloride, and alkyl. Quaternary ammonium salts such as pendyl dimethyl ammonium chloride: alkyl betaines such as lauryl betaine, stearyl betaine, lauryl carboxymethyl hydroxyethyl imidazolinium betaine; and amine oxides such as lauryl dimethylamine oxide.

  Examples of the nonionic surfactant include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether such as polyoxyethylene higher alcohol ether, and polyoxyethylene. Polyoxyethylene alkylaryl ethers such as nonylphenyl ether; polyoxyethylene derivatives; sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate Fatty acid esters such as sorbitan and sorbitan distearate; polyoxyethylene sorbitan monolaurate, polyoxyethylene Polyoxyethylene sorbitan such as Tylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate Fatty acid esters; polyoxyethylene sorbitol fatty acid esters such as polyoxyethylene sorbite tetraoleate; glycerin fatty acid esters such as glycerol monostearate, glycerol monooleate, and self-emulsifying glycerol monostearate; polyethylene glycol monolaurate, polyethylene glycol Monostearate, polyethylene glycol distearate, polyethylene glycol Polyoxyethylene fatty acid esters, such as oleate polyoxyethylene alkylamine, polyoxyethylene hardened castor oil, alkyl alkanol amide.

  In order to perform surface treatment of magnesium hydroxide particles using such a surface treatment agent, a known dry method or wet method can be applied. As a dry method, the surface treatment agent may be added in a liquid, emulsion, or solid state with stirring using a mixer such as a Henschel mixer, and the magnesium hydroxide particles may be sufficiently mixed with or without heating. As a wet method, a surface treatment agent is added in a solution state or an emulsion state to an aqueous solvent or a non-aqueous solvent slurry by adding magnesium hydroxide particles, and mechanically mixed at a temperature of, for example, about 1 to 100 ° C. In this case, the non-aqueous solvent may be removed by drying or the like. Examples of the non-aqueous solvent include isopropyl alcohol and methyl ethyl ketone. The addition amount of the surface treatment agent can be appropriately selected.However, when the dry method is adopted, the surface treatment level tends to be uneven compared to the wet method. good. Specifically, the range is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, based on 100% by mass of the magnesium hydroxide particles. When the wet method is employed, the content is preferably in the range of 0.1 to 5% by mass, more preferably 0.3 to 3% by mass, based on 100% by mass of the magnesium hydroxide particles, from the viewpoint of sufficient surface treatment and prevention of aggregation of the surface treating agent. % Is more preferable.

  The magnesium hydroxide particles having been subjected to the surface treatment can be carried out by appropriately selecting means such as granulation, drying, pulverization, and classification as necessary. The physical property values of the magnesium hydroxide particles before the surface treatment are as described above, but since the ratio of the surface treatment is a small amount relative to the magnesium hydroxide particles, the magnesium hydroxide particles after the surface treatment Can be almost the same as those of the magnesium hydroxide particles before the surface treatment. Therefore, description of each physical property value of the magnesium hydroxide particles after the surface treatment is omitted here.

[Production method of magnesium hydroxide particles]
In the method for producing magnesium hydroxide particles of the present invention, an alkali metal hydroxide is added to a suspension containing magnesium hydroxide so as to be more than 800 parts by mass relative to 100 parts by mass of solid magnesium hydroxide. And a hydrothermal treatment at a temperature exceeding 230 ° C.

  In the present invention, magnesium hydroxide as a raw material is typically obtained as follows. An aqueous solution of magnesium chloride or a hydrate thereof is prepared, and an alkali (for example, an aqueous solution of sodium hydroxide) is added thereto to obtain a suspension. The suspension is subjected to hydrothermal treatment to obtain a slurry. Is filtered, washed, and dried to produce a desired magnesium hydroxide. In the state of the suspension, the particle properties such as the average particle diameter of the raw material magnesium hydroxide can be adjusted by a known pulverization method (for example, a wet pulverization method). When performing the surface treatment as a post-process by a wet method, the slurry subjected to the hydrothermal treatment is filtered and washed, and then returned to pure water to obtain a magnesium hydroxide slurry, and a surface treatment agent is added. Is preferred. The above-mentioned hydrothermal treatment can be performed by performing heat treatment at 100 to 250 ° C. for about 1 to 10 hours with stirring in a known pressure-resistant heating vessel such as an autoclave. Thereafter, if necessary, washing, dehydration, granulation, drying, pulverization, classification, and the like can produce surface-treated magnesium hydroxide.

  As the magnesium chloride or a hydrate thereof that can be used in the above step, water-soluble magnesium salts such as magnesium chloride hexahydrate, magnesium chloride dihydrate, and magnesium chloride anhydrate are preferably exemplified. Usually, the water-soluble magnesium salt is used as an aqueous solution. In addition, seawater or irrigation may be used as a magnesium raw material. The concentration of magnesium ion in each aqueous solution is preferably 0.01 to 5 mol / L, and more preferably 0.05 to 4 mol / L, from the viewpoint of allowing the reaction to proceed sufficiently.

  As the alkali that can be used in the above step, for example, an alkali metal hydroxide, an alkaline earth metal hydroxide, or the like can be used. As the alkali metal hydroxide, sodium hydroxide, potassium hydroxide, or the like can be used. As the alkaline earth metal hydroxide, magnesium hydroxide, calcium hydroxide and the like can be used. The alkali concentration of the alkaline aqueous solution may be about 0.1 to 18N, preferably 0.5 to 15N.

  A suspension containing magnesium hydroxide can be prepared by reacting the water-soluble magnesium salt prepared in the above procedure with an aqueous alkali solution at about 1 to 100 ° C. for 0.01 to 10 hours.

In the present invention, magnesium hydroxide as a raw material can be produced by the above procedure, but can be used for both natural products and synthetic products, and can be obtained as a commercial product. In the present invention, magnesium hydroxide as a raw material can be used by hydrating magnesium oxide. From the viewpoint of improving fluidity, mechanical properties, and the like, magnesium hydroxide as a raw material has a BET specific surface area of less than 0.5 m ² / g and an average particle diameter of 10 μm or more. Is preferably contained in the resulting magnesium hydroxide. In addition, each physical property value (each physical property value including the BET specific surface area and the average particle diameter) of magnesium hydroxide as a raw material can adopt the same value as each physical property value of the above-mentioned magnesium hydroxide particles. Therefore, it is omitted here.

  In the present invention, from the viewpoint of producing coarse particles, a suspension containing magnesium hydroxide as a raw material, an alkali metal hydroxide, more than 800 parts by mass relative to 100 parts by mass of magnesium hydroxide solids, preferably 820 parts by mass or more, more preferably 850 parts by mass or more. The upper limit of the amount of the alkali metal hydroxide to be added is not particularly limited from the viewpoint that the effects of the present invention are not impaired, but from the viewpoint of improving productivity, based on 100 parts by mass of magnesium hydroxide solids. It is preferably 2,000 parts by mass or less, more preferably 1500 parts by mass or less, and still more preferably 1200 parts by mass or less. In addition, from the viewpoint of improving productivity, the amount is preferably more than 800 parts by mass and 2,000 parts by mass or less, more preferably 820 parts by mass or more and 1500 parts by mass or less, and 850 parts by mass or more and 1200 parts by mass with respect to 100 parts by mass of magnesium hydroxide solids. Parts or less are more preferred. In the present invention, as the alkali metal hydroxide, for example, lithium hydroxide, sodium hydroxide, potassium hydroxide and the like can be used.

  In the present invention, it is preferable that the suspension obtained by adding the alkali metal hydroxide to the suspension containing magnesium hydroxide in the above-described amount is subjected to hydrothermal treatment. The hydrothermal treatment is carried out in a known pressure-resistant heating vessel such as an autoclave under stirring at a temperature higher than 230 ° C, preferably 235 ° C or higher, more preferably 250 ° C or higher. Although the upper limit of the temperature of the hydrothermal treatment is not particularly limited from the viewpoint that the effects of the present invention are not impaired, from the viewpoint of practicality, it is preferably 350 ° C or lower, more preferably 300 ° C or lower, and more preferably 280 ° C or lower. More preferred. In addition, from the viewpoint of practicality, the temperature is preferably higher than 230 ° C and 350 ° C or lower, more preferably 235 ° C or higher and 300 ° C or lower, further preferably 250 ° C or higher and 280 ° C or lower. The time of the hydrothermal treatment is preferably about 1 to 100 hours, more preferably about 5 to 50 hours. In the present invention, from the viewpoint of producing coarse particles, hydrothermal treatment can be performed at a temperature higher than 230 ° C and 300 ° C or lower for about 1 to 50 hours.

  In the present invention, desired magnesium hydroxide particles can be produced by washing, dehydrating, granulating, drying, pulverizing, and classifying the slurry obtained by the hydrothermal treatment, as necessary.

  In the case where the surface treatment in the subsequent step is performed by a wet method, the slurry subjected to the hydrothermal treatment is filtered and washed, then returned to pure water to obtain a magnesium hydroxide slurry, and a surface treatment agent is added. Is preferred. The above-mentioned hydrothermal treatment can be performed by performing heat treatment at 100 to 250 ° C. for about 1 to 10 hours with stirring in a known pressure-resistant heating vessel such as an autoclave. Thereafter, if necessary, the surface-treated magnesium hydroxide particles can be produced by washing, dehydrating, granulating, drying, pulverizing, classifying, and the like.

  In the present invention, from the viewpoint of producing coarse particles, the magnesium hydroxide particles obtained above are used as seed particles, and the seed particles are added to a suspension containing magnesium hydroxide in an amount of 5% by mass or more based on the magnesium hydroxide solid content. The alkali metal hydroxide is added so as to be more than 800 parts by mass with respect to 100 parts by mass of the solid content of magnesium hydroxide, and hydrothermal treatment can be performed at more than 230 ° C. In the present invention, preferably, the seed particles are added to the suspension containing magnesium hydroxide so as to be 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more of the magnesium hydroxide solid content. it can. The upper limit of the amount of the seed particles is not particularly limited from the viewpoint that the effect of the present invention is not impaired, but is preferably 50% by mass or less and 40% by mass or less from the viewpoint of improving productivity. Is more preferred. In addition, the amount of the seed particles added is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 50% by mass, and more preferably 20% by mass to 40% by mass from the viewpoint of improving productivity. More preferred. In addition, from the viewpoint of producing coarse particles, magnesium hydroxide particles obtained using seed particles can be further used as seed particles.

When the magnesium hydroxide particles obtained above are used as seed particles, the BET specific surface area is less than 0.5 m ² / g and the average particle diameter is 10 μm or more from the viewpoint of improving fluidity, mechanical properties, and the like. It is preferable to use magnesium hydroxide particles as seed particles. In addition, each physical property value (each physical property value including a BET specific surface area and an average particle diameter) of the magnesium hydroxide used as seed particles can adopt the same value as each physical property value of the above-mentioned magnesium hydroxide particles. Therefore, it is omitted here. Further, even when the seed particles are used, the same values as described above can be adopted as the addition amount of the alkali metal hydroxide, the conditions of the hydrothermal treatment, and the like.

[Resin composition]
The resin composition of the present invention is characterized in that the magnesium hydroxide particles are blended in an amount of 5 to 500 parts by mass with respect to 100 parts by mass of the resin. The magnesium hydroxide particles can be preferably blended in an amount of 50 to 300 parts by mass, more preferably 100 to 200 parts by mass, based on 100 parts by mass of the resin.

  Although not particularly limited, it is preferable to use a thermoplastic resin as the resin. Examples of the thermoplastic resin include, but are not limited to, (meth) acrylates such as polymethyl methacrylate (PMMA), ethylene / (meth) acrylate copolymer, and methyl acrylate / methyl methacrylate copolymer alone. Acrylic resin such as polymer or copolymer; high density polyethylene, low density polyethylene, linear low density polyethylene, ultra low density polyethylene, EVA (ethylene vinyl acetate resin), EEA (ethylene ethyl acrylate resin), EMA (ethylene Methyl acrylate copolymer resin), EAA (ethylene acrylic acid copolymer resin), polyethylene resin (PE) such as ultra high molecular weight polyethylene; polypropylene homopolymer, polypropylene resin (PP) such as ethylene propylene copolymer; ABS resin ( Acryloni Polystyrene resin; polycarbonate resin; polyphenylene resin; polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN); nylon 6, nylon 66, nylon 610; Polyamide resins including various nylons such as nylon 612, nylon 11, nylon 12, and nylon 46 are exemplified. These resins may be used alone or in combination of two or more.

  In the present invention, for example, the thermoplastic resin is selected from the group consisting of acrylic resin, polyethylene resin (PE), polypropylene resin (PP), ABS resin, polystyrene resin, polycarbonate resin, polyphenylene resin, polyester resin and polyamide resin. It is preferable to contain at least one resin. From the viewpoint of improving fluidity, mechanical properties, and the like, it is more preferable that the thermoplastic resin contains an acrylic resin and a polyethylene resin (PE).

  The resin composition may contain other additives in addition to the above components as long as the effects of the present invention are not impaired. Examples of such additives include antioxidants, antistatic agents, pigments, foaming agents, plasticizers, fillers, reinforcing agents, flame retardants, crosslinking agents, light stabilizers, ultraviolet absorbers, and lubricants. Can be

  The amount of the other additives is not particularly limited from the viewpoint that the effects of the present invention are not impaired, but is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin.

[Molded body]
A molded article can be obtained using the resin composition. Such a molded article can be obtained by a known molding method after blending a predetermined amount of magnesium hydroxide particles with a resin or the like. Examples of such a molding method include extrusion molding, injection molding, and calendar molding.

  Since the above-mentioned predetermined magnesium hydroxide particles are blended in the molded article, the molded article is excellent in mechanical properties, flame retardancy and the like. Such a molded article can be used for various applications requiring mechanical properties, flame retardancy, and the like. For example, OA equipment, automobile parts (interior / exterior parts), railway vehicles, ships, aircraft, industrial equipment, game machines, Building materials (indoor and housing materials), electrical products (outside air conditioners and refrigerators, so-called general electronic and electrical equipment housing applications), interior decorations, insulated wires, optical fiber cables, sundries, stationery, furniture, musical instruments (recorders) , Mechanical parts and the like.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

[Analysis with magnesium hydroxide particles]
The following analysis was performed on each magnesium hydroxide particle (sample powder) obtained in the following Examples and Comparative Examples. The results of each analysis are shown in Tables 1 and 2 and FIGS.

(1) BET specific surface area A sample powder pretreated at about 130 ° C. for about 30 minutes in an atmosphere of nitrogen gas using an eight-stage preheat unit (manufactured by MOUNTECH) was converted into a BET specific surface area measuring apparatus by Macsorb HM Model-1208. (Mountech) and the BET specific surface area was measured by a nitrogen gas adsorption method.

(2) Average particle size 50 mL of ethanol was placed in a beaker of 100 mL capacity, about 0.2 g of sample powder was put therein, and subjected to ultrasonic treatment (UD-201, manufactured by Tommy Seiko Co., Ltd.) for 3 minutes to prepare a dispersion. The preparation of the laser diffraction method - using a particle size distribution meter (manufactured by Nikkiso Co., Ltd. Microtrac HRA Model 9320-X100), the _{D 50} value of the volume reference average particle diameter ([mu] m), was measured.

(3) Observation of Particles by Scanning Electron Microscope A double-sided tape was stuck on an aluminum sample table, and a sample powder was applied from above on the aluminum sample table by tracing with a spatula spatula. After gold deposition, a 1000-fold photograph of the particle image of the sample powder was taken using a scanning electron microscope (FE-SEM: S-4700 manufactured by Hitachi, Ltd.). 1 to 3 show SEM photographs.

(4) Ratio of the half width of the diffraction peak derived from the [001] plane and the [110] plane in the X-ray diffraction ([001] / [110])
Using an X-ray diffractometer (Rigaku Corporation, RINT-2500, Kα ray of Cu, 40 kV, 50 mA, integrated powder X-ray analysis software “PDXL2”), the scanning interval is 0.03 °, and the scanning speed is 5.0 °. The sample powder was measured in the range of 3 to 60 ° / min. In X-ray diffraction, the ratio of the half width of the diffraction peak derived from the [001] plane to the [110] plane (the half width of the diffraction peak derived from the [001] plane to the half width of the diffraction peak derived from the [110] plane) Ratio = half width of diffraction peak derived from [001] plane / half width of diffraction peak derived from [110] plane) is the half width of diffraction peak of [001] (2θ = 18.6 °) and [110]. ] (2θ = 58.6 °).

<Example 1>
1000 g of NaOH flakes are added to a suspension containing 100 g of magnesium hydroxide having a BET specific surface area of 35 m ² / g and an average particle diameter of 4.4 μm (1000 parts by mass per 100 parts by mass of solid magnesium hydroxide). Part), to a liquid volume of 1.5 L. The prepared suspension was poured into a 2 L-volume autoclave having a liquid contact part made of Teflon (registered trademark), and subjected to a hydrothermal treatment at 250 ° C. for 10 hours with stirring. The suspension after the hydrothermal treatment was subjected to vacuum filtration, and then sufficiently washed with water at a volume 20 times or more the solid content. Then, it was dried at 120 ° C. for 8 hours or more, and pulverized to obtain magnesium hydroxide particles (sample powder).

<Example 2>
Except that 25 g of magnesium hydroxide particles obtained in Example 1 were used as seed particles and added to a suspension containing 75 g of magnesium hydroxide having a BET specific surface area of 35 m ² / g and an average particle size of 4.4 μm. The same operation as in Example 1 was performed to obtain magnesium hydroxide particles.

<Example 3>
Except that 25 g of magnesium hydroxide particles obtained in Example 2 were used as seed particles and added to a suspension containing 75 g of magnesium hydroxide having a BET specific surface area of 35 m ² / g and an average particle diameter of 4.4 μm. The same operation as in Example 1 was performed to obtain magnesium hydroxide particles.

<Example 4>
850 g of NaOH flakes were added (850 parts by mass based on 100 parts by mass of magnesium hydroxide solids), and the procedure of Example 1 was repeated except that the hydrothermal treatment was performed at 235 ° C. for 30 hours. Particles were obtained.

<Comparative Example 1>
The same operation as in Example 1 was performed except that 800 g of NaOH flakes were added (800 parts by mass with respect to 100 parts by mass of solid content of magnesium hydroxide) and the hydrothermal treatment was performed at 200 ° C. for 10 hours. Particles were obtained.

<Comparative Example 2>
After decarbonation treatment of seawater by a conventional method, a magnesium hydroxide slurry was obtained by using lime milk by a known means. Sodium hydroxide was added to the slurry and hydrothermal synthesis was performed to obtain a magnesium hydroxide slurry having a particle size of 6 μm. The slurry was separated by a vacuum filter and dried to obtain magnesium hydroxide particles.

  This magnesium hydroxide powder was emulsified in a stainless steel container having an internal volume of 10 L so as to have a slurry concentration of 6 wt%. The slurry is maintained in a sufficiently stirred state by a stirrer, and magnesium hydroxide crystals are used as seed crystals to continuously supply a 12.7 wt% magnesium chloride solution and 25% aqueous ammonia using a tube pump. While maintaining the temperature at 60 ° C., crystals of magnesium hydroxide were precipitated. The precipitate of magnesium hydroxide was separated by a filter, washed with water and dried at 120 ° C. to obtain magnesium hydroxide particles.

[Analysis and evaluation of resin composition]
The respective magnesium hydroxide particles obtained in the above Examples and Comparative Examples were respectively blended with the following resin to prepare a resin composition, and the resin composition, or a molded article obtained by molding the same, was evaluated as follows. The test was performed. Tables 1 and 2 show the evaluation results.

(5) Evaluation of Fillability and Melt Flow Rate a. Measurement of Fillability and Melt Flow Rate in Table 1 PMMA (Polymethyl methacrylate) resin (trade name: Acrypet SV001, manufacturer: Mitsubishi Chemical Corporation) was used. 150 parts by mass of sample powder (magnesium hydroxide particles) are charged into a Labo Plastomill (manufactured by Toyo Seiki) heated to 220 ° C. with respect to 100 parts by mass of PMMA resin, and the ease of filling in that case is evaluated. did. In the sample powder, a sample in which hunting was settled within 1 minute was designated as {> a sample in which the hunting was settled in more than 1 minute to less than 3 minutes;

  Thereafter, the kneaded material obtained by melt-kneading at 220 ° C. for 5 minutes using a Labo Plastmill was crushed with a resin shredder, and a compound having a size of 5 mm or less was prepared with a sieve having a mesh size of 5 mm. The melt flow rate was measured under the conditions of a weight of 3.8 kg and a temperature of 230 ° C. in accordance with JIS K7210. The target value of the melt flow rate was 3.0 g / 10 minutes or more.

b. Measurement of Fillability and Melt Flow Rate in Table 2 PMMA (Polymethyl methacrylate) resin (trade name: Sumika MGSS, manufacturer: Sumitomo Chemical Co., Ltd.) or EVA (ethylene vinyl acetate) resin (trade name: EV-180, manufacturer : Mitsui DuPont Polychemical Co., Ltd.). Laboplastomill (manufactured by Toyo Seiki Co., Ltd.) heated to 150 parts by mass of a sample powder (magnesium hydroxide particles) at 220 ° C. and EVA resin at 180 ° C. with respect to 100 parts by mass of PMMA resin or EVA resin. And the ease of filling in that case was evaluated. In the sample powder, when the whole amount was filled in less than 1 minute, it was evaluated as ○, when it was less than 1 to 3 minutes, Δ when it was 3 minutes or more.

  Thereafter, the PMMA resin was melt-kneaded at 220 ° C. for 5 minutes to obtain a kneaded product using a Labo Plastomill. The melt flow rate was measured under the conditions of a weight of 3.8 kg and a temperature of 230 ° C. in accordance with JIS K7210. The target value of the melt flow rate was 1.5 g / min or more.

(6) Blackness Transparency was measured by sandwiching a sheet-shaped molded product between a spectrocolorimeter (KONICA MINOLTA) detector and a black plate, and measuring the blackness. The lower the value, the higher the transparency. The target value was less than 78%.

(7) Flexural strength a. Preparation of molded body for measurement After blending 150 parts by mass of sample powder (magnesium hydroxide particles) with PMMA resin (trade name: Sumika MGSS, manufacturer: Sumitomo Chemical Co., Ltd.), Labo Plastomill (Toyo Seiki Co., Ltd.) ), The kneaded material obtained by melt-kneading at 220 ° C. for 5 minutes at a rotation speed of 50 rpm is put into a mold having a space of 125 mm long × 13 mm wide × 3 mm thick and press-molded at 220 ° C. A molded body having a size of 125 mm × width 13 mm × thickness 3 mm was prepared.

b. Measurement of flexural strength The flexural modulus (N / mm ² ) of the molded body was measured based on JIS K7171. Specifically, using an Autograph AG-5000A type manufactured by Shimadzu Corporation, the A method without changing the strain rate was adopted as a test method, the distance between fulcrums was 40 mm, the test speed was 10 mm / min, the radius of the indenter R1 = 2 mm, The test was performed under the condition that the radius R2 of the support was 2 mm. The target value was 69 MPa or more in bending strength.

(8) Tensile test (tensile strength, tensile elongation)
EVA (ethylene vinyl acetate) resin (trade name: EV-180, manufacturer: DuPont Mitsui Polychemicals) was used. 150 parts by mass of sample powder (magnesium hydroxide particles) was melt-kneaded at 180 ° C. for 5 minutes with a Labo Plastomill (manufactured by Toyo Seiki) with respect to 100 parts by mass of EVA resin. It was molded to form a sheet molded body having a thickness of 2 mm. Tensile strength and tensile elongation were measured in accordance with JIS-K-7113 using a test piece punched out from the sheet molded body in a No. 2 dumbbell shape. The target values were 0.9 kgf / mm ² or more in tensile strength and 1000% or more in tensile elongation.

(9) Combustion test (flame retardancy)
Test pieces (length 125 mm, width 13 mm, thickness 3 mm) were obtained in the same procedure as in the above (7) and (8), and a combustion test was performed according to UL94V. The target value was V-0.

(10) Measurement of thermal conductivity The thermal conductivity was measured using a laser flash method. After blending 150 parts by mass of a sample powder (magnesium hydroxide particles) with 100 parts by mass of PMMA resin (trade name: Sumika MGSS, manufacturer: Sumitomo Chemical Co., Ltd.), Labo Plastomill (Toyo Seiki Co., Ltd.) was used. The kneaded product obtained by melt-kneading at 220 ° C. for 5 minutes at a rotation speed of 50 rpm is put into a mold having a space of 125 mm × 13 mm × 1 mm in thickness and press-molded at 220 ° C., and 125 mm × width A molded body having a size of 13 mm and a thickness of 1 mm was prepared. Thereafter, the molded body was cut out so as to have a length of 10 mm, a width of 10 mm and a thickness of 1 mm, and the thermal conductivity was measured using LFA 467 HyperFlash (NETZSCH). The target value was 0.8 W / m · k or more.

  The results of the above analysis and evaluation are shown in Tables 1 and 2 and FIGS.

As shown in Table 1, in the resin compositions prepared using the magnesium hydroxide particles of Examples 1 to 4, the filling property of the PMMA resin was good and the target value of the melt flow rate was 3.0 g. / 10 minutes or more, and good results were obtained. On the other hand, in the case of magnesium hydroxide particles having a large BET specific surface area and a small average particle diameter as in Comparative Example 1, the filling property of the PMMA resin is poor, and the target value of the melt flow rate of 3.0 g / 10 minutes or more could not be reached, and good results could not be obtained. This is because, by controlling the BET specific surface area of the magnesium hydroxide particles to less than 0.5 m ² / g and the average particle diameter to 10 μm or more, the crystal growth of the primary particles is promoted, and the structure of the particles as a particle structure is further improved. It is presumed that since the strength was increased, the filling property into the resin, the fluidity such as the melt flow rate, and the mechanical properties were improved.

  In addition, comparing Examples 1 to 3, it was found that the use of the seed particles as the raw material of the magnesium hydroxide particles allows the particles to be coarsened. As shown in the raw material column of Table 1, by using the magnesium hydroxide particles obtained in Example 1 in Example 2 and the magnesium hydroxide particles obtained in Example 2 in Example 3, the average particle diameter was increased. It became clear that the BET specific surface area became smaller.

  Scanning electron microscope (FESEM) photographs of the magnesium hydroxide particles are shown in FIGS. 1 shows the magnesium hydroxide particles obtained in Example 1, FIG. 2 shows the magnesium hydroxide particles obtained in Example 3, and FIG. 3 shows the magnesium hydroxide particles obtained in Comparative Example 1. In Example 1 (FIG. 1) and Example 3 (FIG. 2), it was observed that the size of each particle was large and that the crystal growth of primary particles was promoted. On the other hand, in Comparative Example 1 (FIG. 3), each of the particles was aggregated, and it was observed that the crystal growth of the particles was different from Examples 1 and 3.

Table 2 shows the ratio ([001] / [110] of the half width of the diffraction peak derived from the [001] plane and the [110] plane in the X-ray diffraction of the magnesium hydroxide particles of Example 4 and Comparative Examples 1 and 2. ]). Further, Table 2 shows the fluidity and mechanical properties when the magnesium hydroxide particles of Example 4 and Comparative Examples 1 and 2 were blended into a PMMA resin or an EVA resin. When evaluated with a PMMA resin, the ratio of the half width of [001] to [110] ([001] / [110]) as in Example 4 was compared to Comparative Examples 1 and 2, and the PMMA resin was Was good, the melt flow rate was high, and the fluidity and mechanical properties such as blackness and thermal conductivity, bending strength, and flame retardancy were also good. As for the thermal conductivity (evaluated with PMMA resin), it was found that the thermal conductivity increased as the BET specific surface area of the magnesium hydroxide particles decreased. When evaluated with an EVA resin, the ratio of the half width of [001] to [110] ([001] / [110]) as in Example 4 was compared with Comparative Examples 1 and 2, and Was good, the melt flow rate was high, and the fluidity and mechanical properties such as blackness, tensile strength, tensile elongation, and flame retardancy were also good. This is presumed to be because the strength of the particles as a structure increased, and the fluidity and mechanical properties such as resin filling properties and melt flow rates could be improved.

Claims (9)

Magnesium hydroxide particles having a BET specific surface area of less than 0.5 m ² / g and an average particle diameter of 10 μm or more.   The water according to claim 1, wherein a ratio ([001] / [110]) of a half width of a diffraction peak derived from a [001] plane and a [110] plane in X-ray diffraction is 0.75 or more and less than 1.15. Magnesium oxide particles.   At least one selected from the group consisting of higher fatty acids, higher fatty acid alkaline earth metal salts, coupling agents, esters composed of fatty acids and polyhydric alcohols, and phosphate esters composed of phosphoric acid and higher alcohols; The magnesium hydroxide particles according to claim 1 or 2, which have been surface-treated with a surface treatment agent.   A resin composition comprising 5 to 500 parts by mass of the magnesium hydroxide particles according to any one of claims 1 to 3 based on 100 parts by mass of the resin.   The resin composition according to claim 4, wherein the resin is a thermoplastic resin.   A molded article comprising the resin composition according to claim 4.   Magnesium hydroxide particles which are added with an alkali metal hydroxide to a suspension containing magnesium hydroxide in an amount of more than 800 parts by mass with respect to 100 parts by mass of solid content of magnesium hydroxide, and subjected to hydrothermal treatment at more than 230 ° C. Manufacturing method. BET specific surface area of less than 0.5 m 2 / ^g, an average magnesium hydroxide particles having a particle diameter of 10μm or more, the production method of magnesium hydroxide particles according to claim 7 comprising in the magnesium hydroxide.   The magnesium hydroxide particles obtained in claim 7 are used as seed particles, and the seed particles are added to a suspension containing magnesium hydroxide so as to be 5% by mass or more of the solid content of magnesium hydroxide. A method for producing magnesium hydroxide particles, comprising adding an oxide in an amount of more than 800 parts by mass with respect to 100 parts by mass of a solid content of magnesium hydroxide, and performing a hydrothermal treatment at more than 230 ° C.