JP6951022B2 - Magnesium hydroxide particles with slow growth rate and low aspect ratio and their manufacturing method - Google Patents

Description

The present invention relates to magnesium hydroxide particles having a small growth rate of crystallite size when the precursor magnesium hydroxide particles are heat-treated, excellent dispersibility, a low aspect ratio, and a low bulk density, a method for producing the same, and magnesium oxide. It relates to a manufacturing method.

Magnesium hydroxide particles are widely used as flame retardants for polymer materials, high-performance materials, heat storage materials, paper coating agents, and the like. Magnesium oxide is used as an antacid for rubber and the like, a filler for resins, and a carrier for catalysts. In any of the applications, in order to exhibit excellent performance, it is required that the particle size of magnesium hydroxide or magnesium oxide is uniform and that it has a property of being highly filled.

In the production method for obtaining fine particles of magnesium hydroxide, the conventional method of shortening the heat treatment time under pressurized conditions results in insufficient denseness of the crystallites constituting the particles, resulting in an angular shape and a high bulk density. Since the aspect ratio is high, it is difficult to further improve the filling property.

Patent Document 1 discloses a method for producing hexagonal columnar magnesium hydroxide particles that can be highly filled in resin or rubber and has excellent dispersibility. In this production method, magnesium oxide particles are pulverized and an organic acid is added in the rehydration step.

However, since the manufacturing process is complicated, the manufacturing cost is high, and it becomes difficult to obtain fine and uniform particles. Further, the obtained magnesium hydroxide particles are hexagonal columnar particles whose crystal outer shape is composed of two upper and lower hexagonal basal planes parallel to each other and six outer peripheral prismatic planes formed between these basal planes. That is, since the edge portion has an angular shape with a sharp angle, the dispersibility, acid resistance, and filling property are not always sufficient when blended with a resin or rubber. Further, it can be expected that the angular shape easily damages the interface with the resin or rubber, and as a result, adversely affects the physical properties and durability of the molded product.

Japanese Unexamined Patent Publication No. 2006-3066659

An object of the present invention is to provide magnesium hydroxide particles and magnesium oxide particles which are excellent in dispersibility when blended in a resin or rubber and can be highly filled, and a method for producing these.

As a result of diligent research to solve the above problems, the present inventors provide a two-step manufacturing process having different pressure, temperature and time in the heat treatment process for growing magnesium hydroxide particles after the synthesis reaction. As a result, the growth of the crystallites constituting the particles is controlled, and as a result, magnesium hydroxide particles having a rounded polygonal shape, a low aspect ratio, a uniform particle size, and a low bulk density are obtained. It was found that the present invention could be completed.

According to the present invention, by providing a two-step heat treatment step, magnesium hydroxide particles having characteristics that cannot be obtained by a conventional production method can be obtained. Since the first heat treatment step is under low temperature and normal pressure conditions, the crystallites constituting the precursor magnesium hydroxide particles become dense. Therefore, even when the second heat treatment is performed under high temperature and pressure conditions, both the growth rate and the growth rate of the crystallite size become slow, the average secondary particle size is uniform and small, and the bulk density is low. Magnesium particles can be obtained. In addition to these characteristics, the obtained magnesium hydroxide particles have a low aspect and a rounded polygonal shape, so that they can be uniformly and highly filled in applications such as organic polymer materials and inorganic materials. The handleability at that time is also good. Therefore, the resin composition containing the magnesium hydroxide particles of the present invention can improve desired properties such as acid resistance, thermal conductivity, and flame retardancy. Further, since the shape of the magnesium hydroxide particles of the present invention is rounded, the blended particles are less likely to damage the contact surface with the resin, and the obtained molded product is excellent in physical properties and durability.

Further, according to the production method of the present invention, since the production equipment does not need to be significantly complicated, the magnesium hydroxide particles of the present invention can be industrially inexpensively, safely and mass-produced.

FIG. 5 is a particle size distribution diagram of precursor particles obtained by treating at 70 ° C. for 22 hours after the reaction in Example 4. It is a particle size distribution map of magnesium hydroxide of Example 4. 6 is an SEM photograph (50,000 times) of the precursor particles obtained by treating the precursor particles at 70 ° C. for 22 hours after the reaction in Example 4. It is an SEM photograph (50,000 times) of magnesium hydroxide of Example 4. FIG. It is an SEM photograph (50,000 times) of magnesium hydroxide of Example 8.

Hereinafter, the magnesium hydroxide particles and magnesium oxide particles of the present invention will be described in detail based on preferred embodiments, but the present invention is not limited to these descriptions.

(Average growth rate of crystallite size)
The magnesium hydroxide particles of the present invention have an average growth rate of crystallite size from the precursor of 0.5 to 200.0%, a preferable upper limit of 190%, and a more preferable upper limit of 170%, which is preferable. The lower limit is 0.6%.

(The bulk density)
The bulk density of the magnesium hydroxide particles of the present invention is 1.5 to 3.0 ml / g, the preferred upper limit is 2.9 ml / g, the more preferred upper limit is 2.8 ml / g, and the preferred lower limit is. It is 1.8 ml / g, and the more preferable lower limit is 2.0 ml / g.

(BET specific surface area and aspect ratio)
BET specific surface area of the magnesium hydroxide particles of the present invention is 0.2~50m ² / g, a preferred upper limit is ^{45 m} 2 / g, and more preferred upper limit is ^{40 m} 2 / g, preferable lower limit is 0.3m ^{It is 2} / g, and the more preferable lower limit is 0.5 m ² / g.
The aspect ratio of the magnesium hydroxide particles of the present invention is 1 to 6, the preferable upper limit is 5, and the more preferable upper limit is 4.

(Average particle size of magnesium hydroxide)
The magnesium hydroxide particles of the present invention have an average particle size MV of 0.1 to 1.5 μm by laser diffraction / scattering particle size distribution measurement, a preferable upper limit of 1.45 μm, and a more preferable upper limit of 1.40 μm. The preferred lower limit is 0.12 μm, and the more preferred lower limit is 0.13 μm.

(Purity of magnesium hydroxide, impurities)
The purity of the magnesium hydroxide particles of the present invention is 99.5% or more, preferably 99.6% or more, and more preferably 99.7% or more.
The total content of Cr, Ni, Ti, Mn, Mo, Fe, Zn, Cd, Co, Pb and Zr contained in the magnesium hydroxide particles of the present invention is 5 to 110 ppm in terms of metal element, and the preferable upper limit is It is 60 ppm, with a more preferred upper limit of 40 ppm.
The content of the water-soluble sodium salt contained in the magnesium hydroxide particles of the present invention is 300 ppm or less in terms of metal elements.

(Average particle size of magnesium oxide)
The magnesium oxide particles obtained by the production method of the present invention have an average particle size MV of 0.1 to 1.5 μm by laser diffraction / scattering particle size distribution measurement, a preferable upper limit of 1.45 μm, and a more preferable upper limit of 1. It is .40 μm, the preferred lower limit is 0.12 μm, and the more preferred lower limit is 0.13 μm.

The method for producing magnesium hydroxide particles of the present invention is
After reacting the aqueous solution of the soluble magnesium salt and the alkaline aqueous solution at 0 to 99 ° C. at a reaction rate of 50 to 400 mol%, as the first heat treatment step, while keeping the temperature at 0.0 to 120 ° C. under normal pressure conditions, 1 The step (a) of obtaining a slurry of the precursor magnesium hydroxide by maintaining it for 0 to 350 hours.
As a second heat treatment step, the slurry of the step (a) is heat-treated for 0.5 to 200 hours while being maintained at 115-265 ° C. under pressurized conditions to obtain a magnesium hydroxide slurry, and a step (b). Step (c) of obtaining magnesium hydroxide particles by filtering, washing and drying the slurry of (b).
including.

The method for producing magnesium hydroxide particles of the present invention is
After obtaining the slurry of the step (a), the magnesium hydroxide cake obtained by further washing with deionized water 5 to 100 times by mass with respect to the solid content of the magnesium hydroxide slurry and filtering is deionized. Step (a') of resuspending in either water or a 0.1-6.0 mol / L soluble magnesium salt aqueous solution to obtain a magnesium hydroxide slurry.
including.

The method for producing magnesium oxide particles of the present invention is
Step (d) of firing the magnesium hydroxide particles of the present invention or the magnesium hydroxide particles obtained by the production method of the present invention at 400 to 1800 ° C. in an air atmosphere.
including.
The preferred upper limit of the firing temperature is 1700 ° C., the more preferred upper limit is 1600 ° C., the preferred lower limit is 450 ° C., and the more preferred lower limit is 500 ° C.

(Magnesium raw material and concentration)
In step (a), a soluble magnesium salt can be used as the magnesium hydroxide raw material of the present invention, preferably magnesium chloride, magnesium chloride dihydrate, magnesium chloride hexahydrate, magnesium sulfate, magnesium nitrate. Hexahydrate, magnesium acetate, bitter juice and the like are preferably mentioned.
In the step (a), the concentration of the soluble magnesium salt used in the present invention can be used at a concentration within a range in which each raw material does not precipitate in the solution. When an aqueous magnesium chloride solution is used, its concentration is 0.1 to 5.7 mol / L, the preferred upper limit is 5.5 mol / L, the more preferred upper limit is 5.0 mol / L, and the preferred lower limit is 0. It is .5 mol / L, and the more preferable lower limit is 1.0 mol / L. When an aqueous magnesium sulfate solution is used, its concentration is 0.1 to 4.6 mol / L, the preferred upper limit is 4.4 mol / L, the more preferred upper limit is 4.2 mol / L, and the preferred lower limit is 0. It is .5 mol / L, and the more preferable lower limit is 1.0 mol / L. When an aqueous magnesium nitrate solution is used, its concentration is 0.1 to 6.0 mol / L, the preferred upper limit is 5.0 mol / L, the more preferred upper limit is 4.5 mol / L, and the preferred lower limit is 0. It is .5 mol / L, and the more preferable lower limit is 1.0 mol / L. When an aqueous magnesium acetate solution is used, its concentration is 0.1 to 8.0 mol / L, the preferred upper limit is 7.0 mol / L, the more preferred upper limit is 6.0 mol / L, and the preferred lower limit is 0. It is .5 mol / L, and the more preferable lower limit is 1.0 mol / L.

(Alkaline raw material and concentration)
In the step (a), as the alkaline raw material of magnesium hydroxide in the present invention, an aqueous solution such as sodium hydroxide, potassium hydroxide, or ammonia is preferably mentioned. The concentration of the alkaline aqueous solution is 1.0 to 18.0 N, the preferred upper limit is 16.0 N, the more preferred upper limit is 12.0 N, the preferred lower limit is 1.5 N, and the more preferred lower limit is 2.0 N. Is.

(Reaction temperature)
In the step (a), the aqueous solution of the soluble magnesium salt and the aqueous alkaline solution are mixed at 0 to 99 ° C. and reacted. The preferred upper limit of the mixing temperature is 90 ° C., the more preferred upper limit is 75 ° C., the preferred lower limit is 20 ° C., and the more preferred lower limit is 35 ° C.

(Reaction rate)
In the step (a), the reaction rate between the aqueous solution of the soluble magnesium salt and the aqueous alkaline solution is 50 to 400 mol% as magnesium, the preferable upper limit is 350 mol%, the more preferable upper limit is 200 mol%, and the preferable lower limit is 60 mol%. The more preferable lower limit is 80 mol%. The reaction rate is shown to be 100 mol% at the time of theoretical measurement of ^{Mg 2+} ion: OH ^{-ion = 1: 2.} When the reaction rate is 50 mol% or less, magnesium hydroxide particles having excellent dispersibility can be obtained, but the recovery rate of the produced magnesium hydroxide is low. Even when the reaction rate is 400 mol% or more, magnesium hydroxide particles having excellent dispersibility can be obtained, but the viscosity of the reactants increases, which makes it difficult to wash with water. Furthermore, the manufacturing cost is high.

(Maintenance temperature and maintenance time of reaction slurry)
In step (a), the reaction slurry is maintained under open conditions to obtain precursor particles. The maintenance temperature is 0.0 to 120 ° C., the preferred upper limit is 115 ° C., the more preferred upper limit is 100 ° C., the preferred lower limit is 20 ° C., and the more preferred lower limit is 40 ° C. The maintenance time is 1.0 to 350 hours, the preferred upper limit is 300 hours, the more preferred upper limit is 280 hours, the preferred lower limit is 1.5 hours, and the more preferred lower limit is 2.0 hours. When the maintenance temperature is lowered, it is better to lengthen the maintenance time.

(Washing and resuspension of precursor particles)
The slurry containing the precursor particles may be used as it is in the next heat treatment step, or may be used in the next heat treatment step after being filtered and / or washed with water and resuspended. In step (a'), the growth rate of particles can be suppressed and the bulk density of magnesium hydroxide can be reduced by adding the steps of filtration and / or washing with water and resuspension. Deionized water or an aqueous solution of soluble magnesium salt can be used as the solution to be resuspended. When the soluble magnesium salt aqueous solution is used, the pH of the slurry is around 7 to 8, and when deionized water is used, the pH of the slurry is around 10.5. Therefore, it is better to use the soluble magnesium salt aqueous solution. The growth of crystallite size can be slowed down when hydrothermal treatment is performed under pressurized conditions in step (b). When a soluble magnesium salt aqueous solution is used, its concentration is 0.1 to 6.0 mol / L, the preferred upper limit is 5.5 mol / L, the more preferred upper limit is 5.0 mol / L, and the preferred lower limit is 0. It is .3 mol / L, and the more preferable lower limit is 0.5 mol / L.

(Heat treatment)
In step (b), the obtained slurry containing the precursor particles is further heat-treated under pressurized conditions. The heat treatment temperature is 115-265 ° C., the preferred upper limit is 250 ° C., the more preferred upper limit is 230 ° C., the preferred lower limit is 120 ° C., and the more preferred lower limit is 130 ° C. The heat treatment time is 0.5 to 200 hours, the preferred upper limit is 180 hours, the more preferred upper limit is 150 hours, the preferred lower limit is 1 hour, and the more preferred lower limit is 1.5 hours.

(Washing with water after heat treatment)
In the step (c), the amount of washing water is 20 to 200 times, preferably 25 to 150 times, more preferably 30 to 100 times, the amount of deionized water based on the mass of magnesium hydroxide. ..

(surface treatment)
The magnesium hydroxide particles and magnesium oxide particles of the present invention can be surface-treated depending on the application. Known compounds can be used as the surface treatment agent. As the surface treatment agent, at least one selected from the group consisting of higher fatty acids, higher fatty acid alkaline earth metal salts, surfactants, coupling agents and phosphoric acid esters consisting of phosphoric acid and higher alcohols shall be used. Is preferable.

Examples of higher fatty acids include higher fatty acids having 10 or more carbon atoms such as stearic acid, lauric acid, palmitic acid, and erucic acid. Examples of higher fatty acid alkaline earth metal salts include alkaline earth metal salts such as magnesium, beryllium, calcium and barium. As the surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant are preferable, and for example, polyoxyethylene uralyl ether, polyoxyethylene stearyl ether, and sorbitandistea. Examples thereof include sorbitan fatty acid esters such as rates, higher alcohol sodium sulfate, coconatamine acetate, and lauryl betaine. Examples of the coupling agent include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, p-triethoxysilylstyrene and the like. Examples of phosphoric acid esters composed of phosphoric acid and higher alcohols include phosphoric acid esters composed of orthophosphoric acid and oleyl alcohol.

As the surface treatment method, known wet methods and dry methods can be applied. In the wet method, the amount of the surface treatment agent added is 0.01 to 15 parts by weight, preferably 1.0 to 12 parts by weight, and more preferably 2 with respect to 100 parts by weight of magnesium hydroxide or magnesium oxide particles. .0 to 10 parts by weight. The surface treatment temperature is 20 to 100 ° C, preferably 40 to 95 ° C, and more preferably 50 to 85 ° C. Examples of the dry treatment include a method in which the surface treatment agent is dispersed in an organic solvent, mixed well with the powder, and the organic solvent can be blown off at 120 ° C.

(Acid resistance)
The surface-treated magnesium hydroxide particles of the present invention have an elution rate of 45 to 60% by weight in 0.1N hydrochloric acid, a preferable upper limit of 58% by weight, and a preferable lower limit of 50% by weight.

(Resin composition)
The present invention includes a resin composition in which magnesium hydroxide or magnesium oxide is mixed with a synthetic resin or synthetic rubber. Examples of resins include polystyrene, polypropylene, polyethylene, copolymers of ethylene with other α-olefins, copolymers of ethylene with vinyl acetate, ethyl acrylate or methyl acrylate, propylene with other α-olefins. Polymers with, polybutene-1,4-methylpentene-1, styrene and acrylonitrile copolymers, styrene and acrylonitrile and butadiene copolymers, ethylene and propylene diene rubber or butadiene copolymers, For thermoplastic resins such as polyvinyl acetate, polyacrylate, polymethacrylate, polyurethane, polyester, polyether, polyamide, polyvinyl chloride, chlorinated polyethylene, phenol resin, melamine resin, epoxy resin, unsaturated polyester resin, alkyd resin, etc. Examples include thermocurable resins. Examples of synthetic rubber include EPDM, SBR, NBR, butyl rubber, isoprene rubber, chlorosulfonated polyethylene, silicone rubber, fluororubber, urethane rubber, acrylic rubber and the like.

The blending amount of magnesium hydroxide or magnesium oxide in the resin composition is 0.5 to 400 parts by weight, preferably 1.0 to 380 parts by weight, more preferably 1.0 to 380 parts by weight, based on 100 parts by weight of the synthetic resin or synthetic rubber. Is 1.5 to 350 parts by weight.

The resin composition of the present invention may contain other flame retardants, flame retardant aids and the like in order to improve physical properties such as flame retardancy. For example, carbon powder, red phosphorus and the like or a mixture thereof are preferable. The blending amount of the flame retardant aid is preferably 15 parts by weight or less with respect to the total amount of the resin composition.

The resin composition of the present invention can also contain other additives, for example, a cross-linking aid, a cross-linking agent, a softening agent, an antioxidant, a weathering agent, a lubricant, an antistatic agent, and an antioxidant. , Foaming agent, colorant and the like. One type of these additives may be blended, or two kinds may be blended. These additives are preferably blended in an amount of 35 parts by weight or less with respect to 100 parts by weight of the resin.

The resin composition of the present invention can be obtained by blending the magnesium hydroxide particles of the present invention and other inorganic particles and organic particles in the resin. Examples of the method of dispersing such a component in the thermoplastic resin include a method of mixing by a single-screw kneader, a twin-screw kneader, a kneader, a roll kneader and the like. The molded body is molded by a press molding machine, a calendar molding machine, or the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded.

Regarding the obtained magnesium hydroxide particles, (1) aspect ratio, (2) particle size distribution and average particle size, (3) crystallite size, growth rate and growth rate, (4) BET specific surface area, and (5) bulk. Regarding the density, (6) acid resistance, (7) flame retardancy of the resin composition, (8) thermal conductivity in the thickness direction, and (9) appearance of the extruded strand, and the obtained magnesium oxide particles, (2). The following methods were used to evaluate the particle size distribution and average particle size, (10) thermal conductivity, and (11) handleability during resin kneading.

(1) Aspect ratio First, an SEM photograph of the dried particles was taken using a Field Emission Scanning Electron Microscope (JSM-7600F, manufactured by JEOL Ltd.). Next, 20 particles are randomly selected from the obtained 20,000 times image, and among the straight lines passing through the center of each particle, the particle diameter represented by the longest straight line is represented by the long diameter and the shortest straight line. The particle size was measured as the minor axis, and the major axis / minor axis ratio was determined. Finally, the average value of the obtained major / minor axis ratios of the 20 points was taken as the aspect ratio.

(2) 80 ml of an aqueous solution of sodium hexametaphosphate having a particle size distribution and an average particle size of 0.2% by weight was placed in a 100 ml glass beaker, 0.8 g of the dried sample powder was placed therein, and ultrasonic treatment was performed for 3 minutes. .. The particle size distribution of this aqueous solution was measured using a laser diffraction / scattering type particle size distribution device (manufactured by MT3000 Nikkiso Co., Ltd.), and the average particle size MV was determined.

(3) Crystallite size, growth rate and growth rate First, using X-RAY DIFFRACTOMETER (manufactured by RINT2000 Rigaku), the (101) plane, (001) plane and the magnesium hydroxide particles after heat treatment and the precursor. The half-value width β of the (110) plane was measured. At that time, the measurement current and the measurement voltage are set to 20 mA and 40 kv, respectively, and the measurement angles 2θ of the (101) plane, the (001) plane and the (110) plane are set to 17 to 20, 36 to 40 and 57 to 60, respectively. The number of smooth points was 31.
By substituting these values into the Scherrer equation, the crystallite sizes of the (101) plane, the (001) plane, and the (110) plane were obtained, respectively.
Scherrer equation: D _hkl = K × λ / (βcosθ)
D _hkl : Crystallite size (Å) perpendicular to the (hkl) plane
K: Scherrer constant λ: Measured X-ray wavelength (Å)
β: Full width at half maximum (radians)
θ: Bragg angle of diffraction line In the equation, K = 0.9 and λ = 1.542.

Next, the growth rate of the crystallite size of the (hkl) plane when the precursor was heat-treated was determined by (Equation 1).
D _hkl growth rate (%) = _(D after heat treatment _hkl - of _{D hkl} / precursors of the precursor _{D hkl} × 100 (Equation 1)

Furthermore, _{the growth rate of D hkl} was determined by (Equation 2).
D Growth rate (Å / hour) of _hkl = _{(D hkl} after heat treatment - _{D hkl} precursors) / heating time (Equation 2)

Finally, the average growth rate of the crystallites was determined by (Equation 3).
Average growth rate of crystallite size (%) = ( _{Growth rate of D 101} + Growth rate of D ₀₀₁ + Growth rate of D ₁₁₀ ) / 3 × 100 (Equation 3)

(4) The specific surface area was measured by the gas adsorption method using a BET specific surface area specific surface area measuring device (trade name: NOVA2000 manufactured by Yuasa Ionics Co., Ltd.).

(5) Bulk Density 10 g of sample powder was placed in a 100 ml graduated cylinder made of glass, and padding was performed 30 times to determine the bulk density.

(6) As an index of acid resistance of acid-resistant magnesium hydroxide, the elution rate in 0.1N hydrochloric acid was measured. First, 100 ml of a 0.1 N hydrochloric acid solution was placed in a 200 ml glass beaker, 0.5833 g of dried magnesium hydroxide powder was added thereto, and the mixture was stirred at 26 ° C. for 5 minutes. Next, after measuring the pH value of the suspension, the suspension was filtered, and the recovered product was dried at 120 ° C. for 5 hours to measure the mass, and the elution rate of magnesium hydroxide was calculated by the following formula. rice field.
Elution rate (%) = (0.5833 g-mass of recovered powder) /0.5833 × 100

(7) Flame Retardant Evaluation Specimen Sample of Resin Composition consists of 100 parts by weight of LLDPE resin (Novatec LL UF-240 Japan Polyethylene Corporation) and 130 parts by weight of magnesium hydroxide particles as a flame retardant. The mixture was kneaded at 160 ° C. and 30 rpm for 5 minutes using a small batch type kneader (manufactured by Brabender, Germany). The kneaded product was molded in a 130 mm × 70 mm × 3 mm mold at 150 ° C. for ² to 5 minutes at 100 kg / cm. The molded product was cut into a size of 130 mm × 15 mm, and flame retardancy was evaluated in accordance with the UL94V standard.

(8) Evaluation of Thermal Conductivity in the Thickness Direction 75 parts by weight of magnesium hydroxide particles are blended as a heat conductive agent with 100 parts by weight of an ethylene / 1-octene copolymer (ENGAGE8200 DuPondau Elastomer Co., Ltd.), and the thickness is 8 mm. A disk-shaped specimen sample of × 30 mmφ was prepared. The thermal conductivity of the sample was measured in a room temperature atmosphere using a 6φ sensor with a hot disk method thermal conductivity measuring device (Kyoto Denshi Kogyo: TPS-2500S).

(9) Appearance of Extruded Strand The surface of the extruded strand obtained from the resin molded product obtained in (7) above was visually evaluated. Regarding the visual evaluation, the surface condition was evaluated as ⊚ for very good, ◯ for good, and Δ for normal.

(10) Thermal conductivity A disk-shaped test having a thickness of 8 mm × 30 mmφ by blending 300 parts by weight of magnesium oxide particles as a heat conductive agent with 100 parts by weight of an ethylene / 1-octene copolymer (ENGAGE8200 Dupondau Elastomer Co., Ltd.). A body sample was prepared. The thermal conductivity of the sample was measured in a room temperature atmosphere using a 6φ sensor with a hot disk method thermal conductivity measuring device (Kyoto Denshi Kogyo: TPS-2500S).

(11) Handleability of powder during resin kneading Comprehensively judging the scattering of powder during kneading, the ease of biting into the screw, and the adhesion to the hopper, all items are good as the handleability of the powder. Those that were good items were indicated by ⊚, those that had good items of 2 to 3 items were indicated by ◯, and those that had good items of 1 item or less were indicated by Δ.

Put 0.4 L of 4.2 mol / L magnesium chloride aqueous solution in a 1.0 L container, slowly add 0.4 L of 8.4 N sodium hydroxide aqueous solution while stirring to react, and stir at 70 ° C. and 500 rpm. While maintaining the mixture under open conditions for 1 hour, a slurry containing precursor particles was obtained.
The obtained slurry containing the precursor particles was placed in a 1.0 L autoclave, heat-treated for 5 hours under pressurized conditions while stirring at 130 ° C. and 500 rpm, and then filtered to control the magnesium hydroxide solid content. It was washed with 20 times more deionized water on a mass basis.
After washing the magnesium hydroxide cake with water again, it is suspended in deionized water, and then 20% colloidal silica (Nissan Chemical Co., Ltd.) corresponding to 3 parts by weight of _{SiO 2 with respect to the mass of magnesium hydroxide solid content at 80 ° C. with stirring.} Snowtex O) manufactured by Kogyo Co., Ltd. was added, treated for 2 hours, washed with deionized water 10 times the solid content, and dried at 120 ° C. for 20 hours to obtain particles of Example 1.

The particles of Example 2 were obtained by the same method as in Example 1 except that the heat treatment temperature in the autoclave was changed to 165 ° C., the heat treatment time was changed to 3 hours, and the surface treatment agent was changed to stearic acid.

Particles of Example 3 were obtained by the same method as in Example 2 except that the maintenance time of the precursor under open conditions was changed to 5 hours.

Particles of Example 4 were obtained by the same method as in Example 2 except that the maintenance time of the precursor under release conditions was changed to 22 hours.

Particles of Example 5 were obtained by the same method as in Example 4 except that the concentration of the sodium hydroxide solution was changed to 16.8N.

Put 25.0 L of 4.2 mol / L magnesium chloride aqueous solution in a 50 L container, slowly add 25.0 L of 8.4 N sodium hydroxide aqueous solution while stirring to react, and stir at 115 ° C. and 250 rpm. The mixture was maintained under open conditions for 2 hours to obtain a slurry containing precursor particles.
The obtained slurry containing the precursor particles was placed in a 50 L autoclave, heat-treated for 3 hours under pressurized conditions while stirring at 165 ° C. and 250 rpm, filtered, and 20% by mass with respect to magnesium hydroxide. Washed with double deionized water.
The magnesium hydroxide cake after washing with water was subjected to the same surface treatment method as in Example 2 to obtain particles of Example 6.

After obtaining a slurry containing the precursor particles by the same method as in Example 4, the slurry containing the obtained precursor particles was filtered, and half of the obtained magnesium hydroxide cake (49 g as powder) was added to 600 ml. It was resuspended in 4.2 mol / L magnesium chloride aqueous solution. The slurry containing the resuspended precursor particles is placed in a 1.0 L autoclave, heat-treated for 5 hours under pressurized conditions while stirring at 140 ° C. and 500 rpm, and then filtered to obtain magnesium hydroxide solid content. On the other hand, it was washed with 20 times more deionized water on a mass basis.
The magnesium hydroxide cake after washing with water was subjected to the same surface treatment method as in Example 2 to obtain particles of Example 7.

After obtaining a slurry containing the precursor particles by the same method as in Example 1 except that the maintenance temperature of the precursor under open conditions was changed to 40 ° C. and the maintenance time was changed to 120 hours, the obtained precursor particles were used. The slurry containing the slurry was filtered, washed with deionized water 20 times by mass with respect to the solid content of magnesium hydroxide, filtered again, and the obtained magnesium hydroxide cake was resuspended in the deionized water.
The slurry containing the resuspended precursor particles is placed in a 1.0 L autoclave, heat-treated for 50 hours under pressurized conditions while stirring at 200 ° C. and 500 rpm, and then filtered to obtain magnesium hydroxide solid content. On the other hand, it was washed with 20 times more deionized water on a mass basis.
The magnesium hydroxide cake after washing with water was subjected to the same surface treatment method as in Example 2 to obtain particles of Example 8.

(Comparative Example 1)
Particles of Comparative Example 1 were obtained by the same method as in Example 6 except that the maintenance step at 115 ° C. for 2 hours under open conditions was eliminated.

(Comparative Example 2)
Put 0.4 L of 2.1 mol / L magnesium chloride aqueous solution in a 1.0 L stainless steel container, slowly add 0.36 L of 4.2 N sodium hydroxide aqueous solution while stirring to react, and stir at room temperature at 500 rpm. While maintaining the mixture under open conditions for 1 hour, a slurry containing precursor particles was obtained.
The obtained slurry containing the precursor particles was placed in a 1.0 L autoclave, heat-treated for 2 hours under pressurized conditions while stirring at 160 ° C. and 500 rpm, and then filtered to control the magnesium hydroxide solid content. It was washed with 20 times more deionized water on a mass basis.
The magnesium hydroxide cake after washing with water was subjected to the same surface treatment method as in Example 2 to obtain particles of Comparative Example 2.

(Comparative Example 3)
Particles of Comparative Example 3 were obtained by the same method as in Comparative Example 2 except that the surface treatment agent was changed to colloidal silica.

(Comparative Example 4)
Particles of Comparative Example 4 were obtained by the same method as in Example 1 of Patent Document (Japanese Unexamined Patent Publication No. 2006-306659). That is, fused MgO having a crystallite diameter of 58.3 × ^10-9 m was pulverized with a ball mill and passed through a 200 mesh sieve by a wet method. The particles that had passed through the sieve were added to a container having an internal volume of 20 L containing 10 L of acetic acid having a concentration of 0.02 mol / L so that the oxide (MgO) concentration was 100 g / L. While maintaining the obtained MgO-containing mixed solution at 90 ° C., a hydration reaction was carried out for 4 hours while stirring using a high-speed stirrer at a peripheral speed of the turbine blades of 10 m / s. The obtained reaction product was sieved through a 500 mesh sieve, and the fine particles that had passed through the sieve were subsequently filtered, washed with water, and dried to obtain magnesium hydroxide particles.

The dried magnesium hydroxide particles obtained in Example 1 were put into a 300 ml alumina crucible and fired at 650 ° C. for 2 hours using an electric furnace to obtain magnesium oxide particles. The obtained magnesium oxide particles are naturally cooled in an electric furnace, then stearic acid is dissolved in alcohol, and the surface is treated with stearic acid corresponding to 2 parts by weight based on the mass of magnesium oxide solids. The particles of Example 9 were obtained.

The particles of Example 10 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Example 2.

The particles of Example 11 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Example 3.

The particles of Example 12 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Example 4.

The particles of Example 13 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Example 5.

The particles of Example 14 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Example 6.

The particles of Example 15 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Example 7.

The particles of Example 16 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Example 8.

(Comparative Example 5)
The particles of Comparative Example 5 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Comparative Example 1.

(Comparative Example 6)
The particles of Comparative Example 6 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Comparative Example 2.

(Comparative Example 7)
The particles of Comparative Example 7 were obtained by the same method as in Example 9 except that the dried magnesium hydroxide particles were changed to those obtained in Comparative Example 4.

For Examples 1 to 8 and Comparative Examples 1 to 4, the physical characteristics of the crystallites are shown in Table 1, and the evaluation of the resin composition and the like are shown in Table 2. The evaluations and the like of Examples 9 to 16 and Comparative Examples 5 to 7 are shown in Table 3.

The magnesium hydroxide particles and magnesium oxide particles of the present invention can be suitably used as fillers for organic polymer materials and inorganic materials, catalysts and carriers for catalysts. Further, the resin composition of the present invention is a resin composition that can be suitably used for aircraft, automobile bodies, railroad vehicles, electronic machines, electronic parts, industrial equipment, and for example, manufacture of molded bodies and molded parts in the relevant field. Used for. Examples thereof include resin materials such as frames, frames, balls, toys, sheets, containers, cases, electric wires, cables, and optical fiber cords coated with the resin composition of the present invention.

Claims (3)

A method for producing magnesium hydroxide particles.
After reacting the aqueous solution of the soluble magnesium salt and the alkaline aqueous solution at 0 to 99 ° C. at a reaction rate of 50 to 400 mol%, as the first heat treatment step, 1.0 while keeping the temperature at 70 to 120 ° C. under normal pressure conditions. Step (a) of obtaining a slurry of precursor magnesium hydroxide by maintaining for ~ 350 hours,
As a second heat treatment step, the slurry of the step (a) is heat-treated for 0.5 to 200 hours while being maintained at 115-265 ° C. under pressurized conditions to obtain a magnesium hydroxide slurry, and the steps (b). The step (c) including the step (c) of filtering, washing and drying the slurry of (b) to obtain magnesium hydroxide particles is included.
A method for producing magnesium hydroxide particles, wherein the average growth rate of crystallite size before and after the second heat treatment step is 0.5 to 190%. A method for producing magnesium hydroxide particles.
After obtaining the slurry of the step (a), the magnesium hydroxide cake obtained by further washing with deionized water 5 to 100 times by mass with respect to the solid content of the magnesium hydroxide slurry and filtering is deionized. Step (a') of resuspending in either water or a 0.1-6.0 mol / L soluble magnesium salt aqueous solution to obtain a magnesium hydroxide slurry.
The method for producing magnesium hydroxide particles according to claim 1. It is a method for producing magnesium oxide particles .
請Motomeko 1 or 2 magnesium hydroxide particles obtained by the method described in, in an air atmosphere, firing at from 400 to 1,800 ° C. (d),
A method for producing magnesium oxide particles, including.

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