WO2016163562A1

WO2016163562A1 - Magnesium hydroxide particles and method for producing same

Info

Publication number: WO2016163562A1
Application number: PCT/JP2016/061957
Authority: WO
Inventors: 興東王; 康平大堀; 純子武藤; 浩一根立
Original assignee: 協和化学工業株式会社
Priority date: 2015-04-10
Filing date: 2016-04-07
Publication date: 2016-10-13
Also published as: TW201702182A; JP2016199460A

Abstract

The purpose of the present invention is to provide magnesium hydroxide particles and magnesium oxide particles, which have fine and uniform particle diameters, while having high purity and excellent dispersibility. The present invention is a method for producing magnesium hydroxide particles, which comprises: a step (i) wherein an aqueous solution of a soluble magnesium salt is reacted with an aqueous alkaline solution, thereby producing a slurry containing magnesium hydroxide particles; a step (ii) wherein the thus-obtained slurry is subjected to a heat treatment at 0-100°C for 5-500 hours at atmospheric pressure; a step (iii) wherein a cake containing the magnesium hydroxide particles is separated from the heat-treated slurry and purified; and a step (iv) wherein the separated and purified cake is dried, thereby obtaining magnesium hydroxide particles.

Description

Magnesium hydroxide particles and method for producing the same

The present invention relates to magnesium hydroxide particles having a fine and uniform particle size, high purity and excellent dispersibility, and a method for producing the same.

Magnesium hydroxide is widely used as a flame retardant for polymer materials, highly functional materials, catalysts and the like. Magnesium oxide is used as a fiber acid acceptor, electromagnetic steel material, resin filler, catalyst, catalyst carrier, and the like. In order to exhibit excellent performance in these applications, the magnesium hydroxide particles and the magnesium oxide particles are required to have fine and uniform particle diameters, high purity, and excellent dispersibility.
As a method for producing fine magnesium hydroxide particles, there is disclosed a method of producing magnesium hydroxide particles of 5 to 80 nm by vapor phase oxidation method, and further contacting these magnesium oxide particles with water vapor to produce magnesium hydroxide. (Patent Document 1). This method is expensive to manufacture and difficult to produce in large quantities. Moreover, since it contacts with water vapor | steam in the manufacturing process which synthesizes magnesium hydroxide from magnesium oxide, it is difficult to obtain highly dispersed particles.
In recent years, a method using an autoclave has been adopted as a method for producing magnesium hydroxide. Patent Document 2 describes a method of producing magnesium hydroxide particles by reacting an aqueous magnesium chloride solution and an aqueous alkaline solution to produce a magnesium hydroxide slurry, and maintaining the temperature at 101 to 200 ° C. In this manufacturing method, since the time for growing the crystal is short, the aggregate formed immediately after the synthesis grows while maintaining the aggregation. As a result, the finally obtained magnesium hydroxide particles contain a large amount of agglomerates, so that it is difficult to obtain those having excellent dispersibility. Moreover, in this manufacturing method, when there are many alkali raw materials, since impurities elute from an autoclave and an impurity mixes, it is necessary to limit a reaction rate.
JP 2007-137694 A JP 2012-72004 A

An object of the present invention is to provide magnesium hydroxide particles having a fine and uniform particle diameter, high purity and excellent dispersibility, and a method for producing the same. Another object of the present invention is to provide magnesium oxide particles having a fine and uniform particle diameter, high purity and excellent dispersibility.
When the present inventors react an aqueous solution of a soluble magnesium salt with an alkaline aqueous solution and heat-treat it under atmospheric pressure at a low temperature for a long time, compared with the case of using an autoclave or the like and applying heat at a high temperature under pressure, it is finer. The present inventors have found that magnesium hydroxide particles having a uniform particle size, high purity, and excellent dispersibility can be obtained.
That is, the present invention includes the following inventions.
1. (I) reacting an aqueous solution of a soluble magnesium salt with an aqueous alkali solution to produce a slurry containing magnesium hydroxide particles,
(Ii) The obtained slurry was heat-treated at 0 to 100 ° C. under atmospheric pressure for 5 to 500 hours,
(Iii) separating and purifying the cake containing magnesium hydroxide particles from the heat-treated slurry, and (iv) drying the separated and purified cake to obtain magnesium hydroxide particles.
The manufacturing method of the magnesium hydroxide particle | grains including each process.
2. 2. The method according to item 1 above, wherein the soluble magnesium salt is magnesium chloride or magnesium sulfate.
3. 2. The method according to item 1, wherein the aqueous alkaline solution is an aqueous solution of sodium hydroxide.
4). 2. The production method according to item 1 above, wherein 0.1 to 5.7 mol / L of a soluble magnesium salt is reacted with 1.0 to 18.0 N aqueous alkali solution.
5. The resulting magnesium hydroxide particles are
(A) The average secondary particle size (MV) is 50 to 800 nm,
(B) D ₅₀ / MV is 0.70 to 0.99, where D ₅₀ is a volume-based cumulative 50% particle diameter by laser diffraction scattering particle size distribution measurement,
(C) The OH desorption temperature in thermogravimetric analysis when heated at 10 ° C./min in an air atmosphere is 360 to 388 ° C.,
The manufacturing method of the preceding clause 1.
6). (A) The average secondary particle size (MV) is 50 to 800 nm,
(B) D ₅₀ / MV is 0.70 to 0.99, where D ₅₀ is a volume-based cumulative 50% particle diameter by laser diffraction scattering particle size distribution measurement,
(C) The OH desorption temperature in thermogravimetric analysis when heated at 10 ° C./min in an air atmosphere is 360 to 388 ° C.,
Magnesium hydroxide particles characterized by the above.
7). 7. Magnesium hydroxide particles according to item 6 above, wherein the Cl ion content is 50 to 300 ppm.
8). 7. Magnesium hydroxide particles according to item 6 above, wherein the content of SO ₄ ions is 50 to 300 ppm.
9. 7. Magnesium hydroxide particles according to item 6, wherein the BET specific surface area is 8.0 to 280 m ² / g.
10. 7. Magnesium hydroxide particles according to item 6, wherein the purity is 99.5% by weight or more.
11. 7. Magnesium hydroxide particles according to item 6, wherein the total content of Cr, Ni, Ti, Mn, Mo, Fe, Zn, Al, Cd, Co, Pb and Zr is 10 to 150 ppm.
12 Magnesium oxide particles obtained by firing the magnesium hydroxide particles according to item 6 at 350 to 1200 ° C.
13 7. A resin composition comprising 100 parts by weight of a synthetic resin and 0.01 to 350 parts by weight of magnesium hydroxide particles according to item 6 above.
14 13. A resin composition comprising 100 parts by weight of a synthetic resin and 0.01 to 350 parts by weight of the magnesium oxide particles according to item 12 above.

FIG. 1 shows an X-ray diffraction spectrum (top) and library search results (bottom) of magnesium hydroxide particles (Example 1) that were heat-treated at 45 ° C. for 140 hours and then dried at 120 ° C. for 20 hours.
FIG. 2 is an SEM photograph of magnesium hydroxide particles (Example 3) taken at 50,000 times.
FIG. 3 is an SEM photograph of the surface-treated magnesium hydroxide particles (Example 7) taken at 50,000 times.
FIG. 4 shows the particle size distribution of magnesium hydroxide particles (Example 1) that were heat-treated at 45 ° C. for 140 hours and then dried at 120 ° C. for 20 hours.
FIG. 5 is a particle size distribution of magnesium hydroxide particles (Example 3).
FIG. 6 is a particle size distribution of the surface-treated magnesium hydroxide particles (Example 7).
FIG. 7 is an SEM photograph of a cross section of a resin composition in which 130 parts by weight of magnesium hydroxide particles (Example 3) are blended with 100 parts by weight of LLDPE resin at a magnification of 10,000 times.
FIG. 8 is an SEM photograph of a cross section of a resin composition obtained by mixing 130 parts by weight of magnesium hydroxide particles (Comparative Example D) with 100 parts by weight of LLDPE resin at a magnification of 10,000 times.
FIG. 9 shows a TG-DTA curve and OH desorption temperature of magnesium hydroxide particles (Example 1) that were heat-treated at 45 ° C. for 140 hours and then dried at 120 ° C. for 20 hours. The desorption temperature of OH was 382.4 ° C.
FIG. 10 shows a TG-DTA curve and OH desorption temperature of magnesium hydroxide particles (Example 3). The desorption temperature of OH was 378.5 ° C.
FIG. 11 shows a TG-DTA curve and OH desorption temperature of magnesium hydroxide particles (Comparative Example A). The desorption temperature of OH was 389.3 ° C.
FIG. 12 shows a TG-DTA curve and OH desorption temperature of magnesium hydroxide particles (Comparative Example D). The desorption temperature of OH was 402.5 ° C.
FIG. 13 shows the X-ray diffraction spectrum (upper) and library search result (lower) of the magnesium oxide particles (Example 11).
FIG. 14 is a SEM photograph of magnesium oxide particles (Example 11) taken at 35,000 times.
FIG. 15 is a particle size distribution of magnesium oxide particles (Example 11).
FIG. 16 is a particle size distribution of magnesium oxide particles (Example 9).

Hereinafter, the magnesium hydroxide particles and the 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.
[Method for producing magnesium hydroxide particles]
The method for producing magnesium hydroxide particles of the present invention includes each step of a reaction step (i), a heat treatment step (ii), a separation and purification step (iii), and a drying step (iv).
<Reaction step (i)>
The reaction step (i) is a step of producing a slurry containing magnesium hydroxide particles by reacting an aqueous solution of a soluble magnesium salt with an aqueous alkaline solution.
(Soluble magnesium salt)
A soluble magnesium salt can be used as the magnesium raw material. Examples of the soluble magnesium salt include magnesium chloride, magnesium chloride dihydrate, magnesium chloride hexahydrate, magnesium nitrate, magnesium acetate, magnesium sulfate, and bitter juice. As the soluble magnesium salt, magnesium chloride or magnesium sulfate is preferred.
The concentration of the soluble magnesium salt is preferably 0.1 to 5.7 mol / L, more preferably 0.5 to 5.5 mol / L, and still more preferably 1.0 to 5.0 mol / L. When a magnesium chloride aqueous solution is used, it is preferably 0.1 to 5.7 mol / L, more preferably 0.5 to 5.5 mol / L, and still more preferably 1.0 to 5.0 mol / L. When a magnesium sulfate aqueous solution is used, it is preferably 0.1 to 4.6 mol / L, more preferably 0.5 to 4.4 mol / L, and still more preferably 1.0 to 4.2 mol / L. .
(alkali)
Examples of the alkaline aqueous solution include aqueous solutions of sodium hydroxide, potassium hydroxide, ammonia and the like. The aqueous alkaline solution is preferably an aqueous solution of sodium hydroxide. The concentration of the alkaline aqueous solution is preferably 1.0 to 18.0 N, more preferably 2.0 to 15.0 N, and still more preferably 3.0 to 12.0 N.
(Reaction rate)
The reaction rate between the aqueous solution of the soluble magnesium salt and the alkaline aqueous solution is 50 to 400 mol%, preferably 60 to 350 mol%, more preferably 80 to 300 mol%, as magnesium. In addition, a reaction rate shows that it is 100 mol% at the time of the theoretical measurement of Mg2 ⁺ ion: OH ^- ion = 1: 2. Even when the reaction rate is 50 mol% or less, magnesium hydroxide fine particles having excellent dispersibility can be obtained, but the recovery rate of the produced magnesium hydroxide is lowered. Further, even when the reaction rate is 400 mol% or more, magnesium hydroxide fine particles having excellent dispersibility can be obtained. However, since the viscosity of the reaction product becomes high and washing with water becomes difficult, the production cost is further increased.
<Heat treatment step (ii)>
The heat treatment step is a step of heat treating the obtained slurry at 0 to 100 ° C. for 5 to 500 hours under atmospheric pressure.
The heat treatment is performed under atmospheric pressure. The higher the heat treatment temperature is, the higher the average secondary particle size of the magnesium hydroxide obtained, because the nano-sized particles dissolve and the growth of primary particles is promoted. Therefore, when it is desired to obtain fine particles while increasing the heat treatment temperature, the heat treatment time must be shortened. On the other hand, when the heat treatment time is shortened, aggregates of primary particles of magnesium hydroxide generated during the synthesis reaction of magnesium hydroxide remain without being sufficiently separated. These aggregates remain as aggregates even after the drying step, and hydrogen bonds and capillarity work strongly on these aggregates, so that the particles after drying are further aggregated.
That is, at a heat treatment temperature higher than 100 ° C., the obtained magnesium hydroxide particles have both a primary particle size and a secondary particle size that are increased if the heat treatment time is lengthened, and aggregates are contained if the heat treatment time is shortened. And dispersibility will deteriorate.
Therefore, the heat treatment temperature is 0 to 100 ° C., preferably 0 to 95 ° C., more preferably 20 to 90 ° C., and further preferably 35 to 85 ° C. Within this range, the crystal growth of the primary particles of magnesium hydroxide is difficult to promote, and the heat treatment time can be extended.
The heat treatment time is 5 to 500 hours, preferably 8 to 400 hours, more preferably 10 to 300 hours. Within this range, the magnesium hydroxide agglomerates generated in the reaction step are sufficiently separated, and hydrogen bonding and capillary action between the fine particles after drying are suppressed, so that the dispersibility having a uniform particle size is achieved. Excellent magnesium hydroxide particles can be obtained.
<Separation and purification step (iii)>
The separation and purification step is a step of separating and purifying the cake containing magnesium hydroxide particles from the heat-treated slurry.
The magnesium hydroxide cake can be separated by filtration. You may filter, washing with water. Purification can be performed by washing with water. In the water washing, it is preferable to resuspend the magnesium hydroxide cake while stirring the magnesium hydroxide cake and water, and then filter this to obtain the magnesium hydroxide cake again. The water is preferably washed in 1 to 4 portions, and more preferably in 1 to 3 portions. The amount of water is preferably 5 to 100 times that of magnesium hydroxide particles on a weight basis.
The conductivity (purity) of water is preferably 100 μS / cm or less, more preferably 10 μS / cm or less, and even more preferably 0.5 μS / cm or less.
About the temperature of water and the water bath at the time of stirring, stirring speed, and stirring time, it can carry out by a well-known method. For example, the temperature of water and the water bath at the time of stirring can be 10 to 80 ° C., the stirring speed can be 100 to 800 rpm, and the stirring time can be 0.5 to 5 hours.
Although impurities in the magnesium hydroxide can be removed by washing with water, the magnesium hydroxide particles obtained after drying aggregate and deteriorate dispersibility. Therefore, in order to obtain magnesium hydroxide particles with few impurities and excellent dispersibility, it is required to reduce impurities contained in magnesium hydroxide after heat treatment and reduce the amount of water used for washing.
In the production method of the present invention, since the heat treatment temperature is 0 to 100 ° C., the crystal structure has a thermodynamically unstable characteristic as compared with magnesium hydroxide produced at a higher heat treatment temperature. For this reason, it is easy to remove impurities such as Cl from the product by washing with water. Therefore, Cl ions in the magnesium hydroxide particles obtained by the production method of the present invention are easily removed by washing with water even when a magnesium chloride aqueous solution is used as a raw material. Moreover, SO ₄ ions in the magnesium hydroxide particles obtained by the production method of the present invention are easily removed by washing with water even when a magnesium sulfate aqueous solution is used as a raw material.
<Drying step (iv)>
The drying step is a step of drying the magnesium hydroxide cake. Drying can be performed by a known method.
<Magnesium hydroxide particles>
The magnesium hydroxide particles of the present invention have a chemical composition represented by Mg (OH) ₂ .
(Average secondary particle size (MV))
The magnesium hydroxide particles of the present invention have an average secondary particle size (MV) of 50 to 800 nm, preferably 80 to 600 nm, more preferably 100 to 500 nm after the drying step.
_{(D 50)}
The D ₅₀ of the magnesium hydroxide particles of the present invention is preferably 35 to 792 nm, more preferably 57.6 to 594 nm, and even more preferably 75 to 495 nm.
_(D 50 / MV)
The D ₅₀ / MV of the magnesium hydroxide particles of the present invention is 0.70 to 0.99, preferably 0.72 to 0.99, more preferably 0.75 to 0.99. Here D ₅₀ is a cumulative 50% particle diameter on a volume basis by a laser diffraction scattering particle size distribution measurement.
_{_(D} 90 _/ _D ₁₀₎
The D ₉₀ / D ₁₀ of the magnesium hydroxide particles of the present invention is preferably 4 or less, more preferably 3.8 or less, and even more preferably 3.5 or less.
(OH release temperature)
The magnesium hydroxide particles of the present invention have an OH desorption temperature of 360 to 388 ° C., preferably 365 to 386 ° C., more preferably 370 to 385 ° C. in thermogravimetric analysis when the temperature is raised at 10 ° C./min in an air atmosphere. It is.
Since the magnesium hydroxide particles of the present invention are heat-treated at a low temperature of 0 to 100 ° C., the crystal structure is characterized by thermodynamically unstable as compared with magnesium hydroxide heat-treated at a higher temperature. Therefore, the magnesium hydroxide particles of the present invention have a lower OH desorption temperature in thermogravimetric analysis than magnesium hydroxide produced by heat treatment at a temperature higher than 100 ° C. As a result, the flame retardancy is excellent.
(BET specific surface area)
The BET specific surface area of the magnesium hydroxide particles of the present invention is preferably 8.0 to 280 m ² / g, more preferably 10.0 to 250 m ² / g, still more preferably 15.0 to 200 m ² / g.
(Cl ion content)
The content of Cl ions in the magnesium hydroxide particles is preferably 50 to 300 ppm, more preferably 50 to 270 ppm, and still more preferably 50 to 250 ppm. The crystal structure of the magnesium hydroxide particles of the present invention is thermodynamically unstable, can easily remove Cl ions by purification, and has a low Cl ion content.
(SO ₄ ion content)
The content of SO ₄ ions in the magnesium hydroxide particles of the present invention is preferably 50 to 300 ppm, more preferably 50 to 270 ppm, and still more preferably 50 to 250 ppm. The crystal structure of the magnesium hydroxide particles of the present invention is thermodynamically unstable, and SO ₄ ions can be easily removed by purification, and the content of SO ₄ ions is small.
(purity)
The purity of the magnesium hydroxide particles of the present invention is preferably 99.5% or more, more preferably 99.6% or more, and further preferably 99.7% or more.
(Total metal content)
The total content of Cr, Ni, Ti, Mn, Mo, Fe, Zn, Al, Cd, Co, Pb and Zr in the magnesium hydroxide particles of the present invention is preferably 10 to 150 ppm, more preferably 15 to 100 ppm. Yes, more preferably 20 to 80 ppm. The crystal structure of the magnesium hydroxide particles of the present invention is thermodynamically unstable, metal impurities can be easily removed by purification, and the content of metal impurities is small.
<Magnesium oxide>
The magnesium oxide particles of the present invention have a chemical composition represented by MgO. The magnesium oxide particles of the present invention can be obtained by firing the magnesium hydroxide particles of the present invention, preferably at 350 to 1200 ° C. The firing temperature is more preferably 400 to 1100 ° C, still more preferably 500 to 1000 ° C.
(Average secondary particle size (MV))
The magnesium oxide particles of the present invention have an average secondary particle size (MV) of preferably 50 to 800 nm, more preferably 80 to 600 nm, and still more preferably 100 to 500 nm.
_{(D 50)}
The D ₅₀ of the magnesium oxide particles of the present invention is preferably 35 to 792 nm, more preferably 57.6 to 594 nm, and further preferably 75 to 495 nm.
_(D 50 / MV)
The D ₅₀ / MV of the magnesium oxide particles of the present invention is preferably 0.70 to 0.99, more preferably 0.72 to 0.99, and even more preferably 0.75 to 0.99. Here, D ₅₀ is a volume-based cumulative 50% particle diameter measured by laser diffraction scattering type particle size distribution measurement.
_{_(D} 90 _/ _D ₁₀₎
The D ₉₀ / D ₁₀ of the magnesium oxide particles of the present invention is preferably 4 or less, more preferably 3.8 or less, and even more preferably 3.5 or less.
(BET specific surface area)
The BET specific surface area of the magnesium oxide particles of the present invention is preferably 1.0 to 280 m ² / g, more preferably 5.0 to 250 m ² / g, still more preferably 10.0 to 200 m ² / g.
(purity)
The purity of the magnesium oxide particles of the present invention is preferably 99.5% or more, more preferably 99.6% or more, and further preferably 99.7% or more.
(Total metal content)
The total content of Cr, Ni, Ti, Mn, Mo, Fe, Zn, Al, Cd, Co, Pb and Zr in the magnesium oxide particles of the present invention is preferably 10 to 150 ppm, more preferably 15 to 100 ppm, Preferably it is 20 to 80 ppm.
<Surface treatment agent>
The magnesium hydroxide particles and magnesium oxide particles of the present invention are preferably surface-treated depending on the application. A known compound can be used as the surface treatment agent. The surface treatment agent is preferably at least one selected from the group consisting of higher fatty acids, anionic surfactants, higher fatty acid alkaline earth metal salts, coupling agents, phosphoric esters comprising phosphoric acid and higher alcohols, and silicone oils. .
Examples of higher fatty acids include stearic acid, erucic acid, palmitic acid, lauric acid, and behenic acid.
Anionic surfactants include polyethylene glycol ether sulfate, amide bond sulfate, ester bond sulfate, ester bond sulfonate, amide bond sulfonate, ether bond sulfonate, ether bond alkylaryl sulfonic acid. Examples thereof include salts, ester-bonded alkyl aryl sulfonates, and amide-bonded alkyl aryl sulfonates.
Examples of the higher fatty acid alkaline earth metal salt include alkaline earth metal salts such as magnesium, beryllium, calcium, and barium.
Examples of coupling agents include r- (2-aminoethyl) aminopropyltrimethoxysilane, r- (2-aminoethyl) aminopropylmethyldimethoxysilane, r-methacryloxypropyltrimethoxysilane, N-β- ( N-vinylbenzylaminoethyl) -r-aminopropyltrimethoxysilane / hydrochloride, r-glycidoxypropyltrimethoxysilane, r-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxy Silane, r-chloropropyltrimethoxysilane, hexamethyldisilazane, r-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, r-c Ropropylmethyldimethoxysilane, r-mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, β- (3,4 epoxy cyclohexyl) ) Ethyltrimethoxysilane, r-glycidoxypropylmethylethoxysilane, r-glycidoxypropyltriethoxysilane, r-methacryloxypropylmethyldimethoxysilane, r-methacryloxypropylmethyldiethoxysilane, r-methacryloxypropyl Triethoxysilane, N-β (aminoethyl) r-aminopropylmethyldimethoxysilane, N-β (aminoethyl) r-aminopropyltrimethoxysilane, N β (aminoethyl) r-aminopropyltriethoxysilane, r-aminopropyltrimethoxysilane, r-aminopropyltriethoxysilane, N-phenyl-r-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane Silane coupling agents such as γ-methacryloxypropyltrimethoxysilane, isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, isopropyl tridecylbenzenesulfonyl Titanate, tetraoctyl bis (ditridecyl phosphite) titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, isopropyl tridodecy Benzenesulfonyl titanate, tetraisopropylbis (dioctylphosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis- (ditridecyl) phosphite titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyltriocta Titanate coupling agents such as noyl titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, dicumyl phenyloxyacetate titanate, diisostearoyl ethylene titanate Aluminum cups such as acetoalkoxyaluminum diisopropylate A ring agent is mentioned.
Examples of phosphoric acid esters composed of phosphoric acid and higher alcohols include phosphoric acid esters composed of orthophosphoric acid and oleyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol or stearyl alcohol.
Examples of the silicone oil include dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, and cyclic dimethyl silicone oil.
The surface treatment can be performed by a known wet method and dry method. In the wet method, the amount of the surface treatment agent added is preferably 0.5 to 15 parts by weight, more preferably 1.0 to 12 parts by weight, and still more preferably 100 parts by weight of magnesium hydroxide particles and magnesium oxide particles. 2.0 to 10 parts by weight. The surface treatment temperature is preferably 0 to 100 ° C., more preferably 20 to 90 ° C., and further preferably 40 to 80 ° C.
<Resin composition containing magnesium hydroxide particles>
The resin composition of the present invention contains 100 parts by weight of a synthetic resin and 0.01 to 350 parts by weight of the magnesium hydroxide particles.
As synthetic resins, polymers or copolymers of C2 to C8 olefins (α-olefins) such as polyethylene, polypropylene, ethylene / propylene copolymers, polybutene, poly-4-methylpentene-1, etc., these olefins and dienes These copolymers are mentioned. Also, ethylene-acrylate copolymer, polystyrene, ABS resin, AAS resin, AS resin, MBS resin, ethylene / vinyl chloride copolymer resin, ethylene vinyl acetate copolymer resin, ethylene-vinyl chloride-vinyl acetate graft polymer resin, vinylidene chloride, polychlorinated Vinyl, chlorinated polyethylene, chlorinated polypropylene, vinyl chloride copolymer, vinyl acetate resin, phenoxy resin, polyacetal, polyamide, polyimide, polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene terephthalate, polybutylene terephthalate, methacrylic resin, etc. A thermoplastic resin can be illustrated.
Furthermore, thermosetting resins such as epoxy resins, phenol resins, melamine resins, unsaturated polyester resins, alkyd resins, and urea resins can be exemplified. Moreover, synthetic rubbers such as EPDM, butyl rubber, isoprene rubber, SBR, NBR, chlorosulfonated polyethylene, NIR, urethane rubber, butadiene rubber, acrylic rubber, silicone rubber, and fluorine rubber can be exemplified.
The compounding amount of the magnesium hydroxide particles is 0.01 to 350 parts by weight, preferably 0.1 to 320 parts by weight, more preferably 0.5 to 300 parts by weight with respect to 100 parts by weight of the synthetic resin.
<Resin composition containing magnesium oxide>
The resin composition of the present invention contains 100 parts by weight of a synthetic resin and 0.01 to 350 parts by weight of the magnesium oxide particles.
The synthetic resin is preferably at least one selected from the group consisting of thermoplastic resins, thermosetting resins and rubbers. As thermoplastic resin, polyethylene, copolymer of ethylene and α-olefin, ethylene and vinyl acetate, copolymer of ethylene and ethyl acrylate, copolymer of ethylene and methyl acrylate, polypropylene, propylene and others Α-olefin copolymer, polybutene-1, poly-4-methylpentene-1, polystyrene, copolymer of styrene and acrylonitrile, copolymer of ethylene and propylene diene rubber or butadiene, polyvinyl acetate, polyvinyl Examples include alcohol, polyacrylate, polymethacrylate, polyurethane, polyester, polyether, polyamide, ABS, polycarbonate, and polyphenylene sulfide.
Examples of the thermosetting resin include phenol resin, melamine resin, epoxy resin, unsaturated polyester resin, alkyd resin, and the like. As rubber, EPDM, SBR, NBR, copolymerized rubber of ethylene and other α-olefins such as propylene, octene, butyl rubber, chloroprene rubber, isoprene rubber, chlorosulfonated rubber, silicone rubber, fluorine rubber, chlorinated butyl rubber, Examples include brominated butyl rubber, epichlorohydrin rubber, and chlorinated polyethylene rubber.
The content of magnesium oxide particles is 0.01 to 350 parts by weight, preferably 0.1 to 320 parts by weight, and more preferably 0.5 to 300 parts by weight with respect to 100 parts by weight of the synthetic resin.

EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited by these Examples, unless the summary is exceeded. In the examples, each characteristic was measured by the following method.
(1) SEM photograph Using Field Emission Scanning Electron Microscope (JSM-7600F, manufactured by JEOL Ltd.), a photograph after kneading into particles after drying, particles after baking treatment and resin was taken.
(2) Analysis by X-ray diffraction method Qualitative analysis of the obtained magnesium hydroxide particles and magnesium oxide particles was performed using X-RAY DIFFRACTOMETER (RINT2000, manufactured by Rigaku).
(3) Particle size distribution and particle size 80 ml of a 0.2 wt% sodium hexametaphosphate aqueous solution was placed in a 100 ml glass beaker, and 0.8 g of the dried sample powder was added thereto and subjected to ultrasonic treatment for 3 minutes. About this aqueous solution, using a laser diffraction scattering type particle size distribution apparatus (MT3000, manufactured by Nikkiso Co., Ltd.), the average secondary particle size (MV), the volume-based cumulative 50% particle size (D ₅₀ ), and the volume-based cumulative 90 % Particle size (D ₉₀ ) and volume-based cumulative 10% particle size (D ₁₀ ) were measured.
(4) BET specific surface area A specific surface area was measured by a gas adsorption method using a specific surface area measuring device (NOVA2000, manufactured by Yuasa Ionics).
(5) Chemical composition The contents of Cl, SO ₄ , Fe, Zn and Al contained in the magnesium hydroxide particles after drying are quantified using a fluorescent X-ray (XRF) analyzer (RIX2000, manufactured by Rigaku). Analysis was carried out.
In order to measure the content of Cr, Ti, Mn, Mo, Ni, Cd, Co, Pb and Zr contained in the dried magnesium hydroxide particles, a sample dissolved in an acid was prepared, and an ICP emission spectrometer Quantitative analysis was performed using SPS3500D (manufactured by HITACHI).
(6) Thermogravimetric analysis Thermogravimetric analysis of the obtained magnesium hydroxide particles and magnesium oxide particles was performed using a thermal analyzer (TG-DTA 2000SA, manufactured by Bruker AXS). The sample weight was 10 mg, the air flow rate was 100 ml / min, and the heating rate was 10 ° C./min.
(7) Flame Retardancy Evaluation and Appearance Evaluation of Resin Composition The test specimen is composed of 100 parts by weight of LLDPE resin (linear low density polyethylene, Novatec LLUF-240, Nippon Polyethylene Co., Ltd.) and magnesium hydroxide particles as a flame retardant. 130 parts by weight were mixed and kneaded at 160 ° C. and 30 rpm for 5 minutes by a small batch kneader (manufactured by Brabender). The kneaded material was molded in a mold of 130 mm × 70 mm × 3 mm at 150 ° C. and 100 kg / cm ² for 5 minutes. The molded product was cut into a size of 130 mm × 15 mm, and flame retardancy was evaluated according to the UL94V standard (1/8 inch).
(8) Evaluation of Dispersion State of Magnesium Hydroxide Particles in Resin Molded Product Visually observe the dispersion state of magnesium hydroxide particles in the range of 5 × 5 cm with respect to the surface of the molded product produced by the method of (7). evaluated. “○” when the aggregated primary particles of magnesium hydroxide are not observed, “△” when 1 to 4 are observed, “△”, when 5 or more are observed, “×” As evaluated.
(9) Evaluation of scorch characteristics of rubber composition For 100 parts by weight of chloroprene rubber (CR) (M-40, manufactured by Denki Kagaku Kogyo), 4 parts by weight of magnesium oxide as an acid acceptor and 1 of anti-aging agent PA Parts by weight, 5 parts by weight of two types of ZnO as a crosslinking agent, 50 parts by weight of carbon black SRF · CB (Seast S, manufactured by Tokai Carbon Co., Ltd.) and 0.5 parts by weight of a vulcanization accelerator 22 as reinforcing fillers After mixing and kneading for 10 minutes at 40 ° C. with an open roll, press vulcanization treatment was performed at 153 ° C. for 30 minutes to prepare a sample. The molded article for measuring compression set was subjected to a press vulcanization treatment for 40 minutes. About a molded article, according to JIS K6251 and JIS K6253, 200% modulus (M200), 400% modulus (M400), 600% modulus (M600) of vulcanized rubber, strength at break (TB), elongation at break ( EB) and hardness (Shore A hardness) were measured. Regarding the heat aging characteristics, vulcanized rubber was aged in an air atmosphere at 100 ° C. for 168 hours based on JIS K6257, and then the change in Shore A hardness was measured.
(10) Evaluation of dispersion state of magnesium oxide particles in rubber molded product Visually evaluate the dispersion state of magnesium oxide particles in the range of 5 × 5 cm on the surface of the rubber molded product produced by the method of (9). did. “○” if the aggregated primary particles of magnesium oxide were not observed, “◯”, 1 to 4 observed “△”, 5 or more observed as “×” evaluated.
(11) Evaluation of fluidity of pellets of flame retardant resin composition The fluidity of pellets of flame retardant resin composition containing the magnesium hydroxide particles of the present invention is determined by a melt indexer (manufactured by Takara Thermistor Co., Ltd.). MFR was measured under the condition of 190 ° C. and 21.6 kg.
(12) Evaluation of Colorability of Flame Retardant Resin Composition The colorability of the flame retardant resin composition blended with the magnesium hydroxide particles of the present invention is determined using a colorimetric colorimeter (Nippon Denshoku). 3 points in the same sheet were measured by Kogyo Co., Ltd., and the average value was obtained.
(13) Evaluation of tensile property of flame retardant resin composition The tensile property of the flame retardant resin composition containing the magnesium hydroxide particles of the present invention is a universal testing machine (instrument tester) The tensile properties were evaluated by Ron Corporation.
Examples 1 to 10 and Comparative Examples A to D (magnesium hydroxide)
Example 1
At normal pressure and 20 ° C., put 6.5 L of 4.2 mol / L magnesium chloride aqueous solution into a 20 L stainless steel container, slowly add 6.5 L of 8.4 N aqueous sodium hydroxide solution while stirring, and let it react. The total volume of the solution was adjusted to 16 L with ionic water, and the slurry concentration was adjusted to 100 g / L.
Next, the temperature of the water bath was set to 45 ° C., and heat treatment was performed under a stirring condition of 350 rpm. Table 3 shows the distribution of the particles of the slurry after 1, 5, 24, 43, 48, 52, 69, 91, 115, 120, 123 and 140 hours after the start of the heat treatment.
Further, the slurry after the heat treatment for 140 hours was filtered while adding 20 times the pure water (deionized water, 0.5 μS / cm) on a weight basis to the magnesium hydroxide particles to obtain magnesium hydroxide particles. On the other hand, it was washed twice with 25 times pure water on a weight basis and dried at 120 ° C. for 20 hours. As a result of analysis by an X-ray diffraction method, the obtained particles were magnesium hydroxide (Mg (OH) ₂ ) particles (FIG. 1).
Example 2
At normal pressure and 20 ° C., put 6.5 L of 4.2 mol / L magnesium chloride aqueous solution into a 20 L stainless steel container, slowly add 9.1 L of 12.0 N sodium hydroxide aqueous solution with stirring, and let it react. The total volume of the solution was adjusted to 16 L with ionic water, and the slurry concentration was adjusted to 100 g / L. Thereafter, the temperature of the water bath was set to 60 ° C., and heat treatment was performed for 15 hours under a stirring condition of 350 rpm. Thereafter, in the same manner as in Example 1, filtration, washing with water and drying were performed to obtain magnesium hydroxide particles.
Example 3
Magnesium hydroxide particles were obtained in the same manner as in Example 1 except that the heat treatment temperature was changed to 70 ° C. and the heat treatment time was changed to 15 hours.
Comparative Example A
800 ml of the same slurry as the slurry before heat treatment in Example 3 was taken and reacted in a 0.98 L autoclave (manufactured by Nitto Koatsu Co., Ltd.). Thereafter, the temperature was set to 150 ° C., and heat treatment was performed for 1 hour under a stirring condition of 500 rpm. Thereafter, filtration, washing with water and drying were performed in the same manner as in Example 1 to obtain magnesium hydroxide particles.
Example 4
Magnesium hydroxide particles were obtained in the same manner as in Example 3 except that the heat treatment temperature was changed to 90 ° C.
Comparative Example B
Magnesium hydroxide particles were obtained in the same manner as in Comparative Example A except that the heat treatment time was changed to 3 hours.
Example 5
At normal pressure and 20 ° C., put 6.5 L of 4.2 mol / L magnesium chloride aqueous solution into a 20 L stainless steel container, slowly add 3.9 L of 8.4 N sodium hydroxide aqueous solution with stirring, and react to remove. The total volume of the solution was adjusted to 10.6 L with ionic water, and the concentration of the slurry was 90 g / L.
The temperature of the water bath was set to 70 ° C., and heat treatment was performed for 15 hours under a stirring condition of 350 rpm. Thereafter, filtration, washing with water and drying were performed in the same manner as in Example 1 to obtain magnesium hydroxide particles.
Comparative Example C
800 ml of the same slurry as the slurry before heat treatment of Example 5 was taken and reacted in a 0.98 L autoclave (manufactured by Nitto Koatsu Co., Ltd.), set at 150 ° C., and heat treated for 1 hour under stirring conditions of 500 rpm. Thereafter, in the same manner as in Example 1, filtration, washing and drying were performed to obtain magnesium hydroxide particles.
Comparative Example D
Commercially available magnesium hydroxide particles (Kisuma 5A, manufactured by Kyowa Chemical Industry Co., Ltd.).
Example 6
At normal pressure and 20 ° C., 4.0 L of a 5.5 mol / L magnesium chloride aqueous solution is placed in a 20 L stainless steel container, and 8.25 L of 16.0 N sodium hydroxide aqueous solution is slowly added with stirring to react. The total volume of the solution was adjusted to 12.83 L with ionic water, and the concentration of the slurry was 100 g / L.
The temperature of the water bath was set to 70 ° C., and heat treatment was performed for 15 hours under a stirring condition of 350 rpm. Thereafter, filtration, washing with water and drying were carried out in the same manner as in Example 1 to obtain magnesium hydroxide particles.
Example 7
After processing in the same manner as in Example 3, surface treatment was performed with 3.0% by weight of stearic acid based on the solid content to obtain magnesium hydroxide particles.
Example 8
Magnesium hydroxide particles were obtained in the same manner as in Example 3 except that the magnesium raw material was changed to 4.2 mol / L MgSO ₄ .
Example 9
Magnesium hydroxide particles were obtained in the same manner as in Example 1 except that the heat treatment temperature was changed to 20 ° C. and the heat treatment time was changed to 165 hours.
Example 10
Magnesium hydroxide particles were obtained in the same manner as in Example 1 except that the heat treatment temperature was changed to 99 ° C. and the heat treatment time was changed to 10 hours.
(Relationship between heat treatment conditions and particle size distribution)
In the method for producing magnesium hydroxide particles of the present invention, as is apparent from the distribution state of the slurry particles after the start of heat treatment (Table 3 (Example 1)), the aggregates produced during the reaction are separated as the heat treatment time becomes longer. It can be confirmed that the particles are fine and uniform.
(About particle size distribution)
The magnesium hydroxide particles of the present invention have a fine and uniform particle diameter regardless of the presence or absence of surface treatment. As can be seen from the SEM photograph (FIG. 2 (Example 3)) of the magnesium hydroxide particles not subjected to the surface treatment and the SEM photograph after the surface treatment (FIG. 3 (Example 7)), there is no conspicuous aggregate. It can be confirmed that the particles are uniform. Further, the particle size distribution of the magnesium hydroxide particles not subjected to the surface treatment (FIG. 4 (Example 1), FIG. 5 (Example 3)) and the particle size distribution of the particles after the surface treatment (FIG. 6 (Example 7)). Can be confirmed to have a fine and uniform particle diameter.
(About dispersibility)
The magnesium hydroxide particles of the present invention have excellent dispersibility despite being fine particles. The SEM photograph (FIG. 7 (Example 3)) of the cross section of the resin composition which knead | mixed the magnesium hydroxide particle of this invention in LLDPE resin, and the resin composition which knead | mixed commercially available magnesium hydroxide particle in LLDPE resin As is apparent from comparison with a cross-sectional SEM photograph (FIG. 8 (Comparative Example D)), the magnesium hydroxide particles of the present invention are uniformly dispersed without being aggregated even when kneaded into a resin. Can be confirmed.
(OH release temperature)
The magnesium hydroxide particles of the present invention have a lower OH desorption temperature in thermogravimetric analysis than magnesium hydroxide that has been heat-treated at a temperature higher than 100 ° C. The desorption temperatures of OH in the thermogravimetric analysis of the magnesium hydroxide particles of the present invention are 382.4 ° C. (FIG. 9 (Example 1)) and 378.5 ° C. (FIG. 10 (Example 3)).
These OH desorption temperatures were 389.3 ° C. (FIG. 11 (Comparative Example A)) and 402.5 ° C. (FIG. 12 (Comparative Example D)). Compared with low characteristics. This is considered to be because the magnesium hydroxide particles of the present invention have a thermodynamically weak crystal structure. Therefore, there is a feature that it can be easily removed by washing with impurities such as Cl incorporated in the magnesium hydroxide particles.
For Examples 1 to 10 and Comparative Examples A to D, the synthesis conditions (raw material concentration, raw material usage, reaction rate, heat treatment conditions) and the characteristics of the obtained magnesium hydroxide particles (MV, D ₉₀ / D ₁₀ , D ₅₀₎ , D ₅₀ / MV, BET specific surface area) are shown in Table 1 (1) and Table 1 (2). For Examples 1 to 8 and Comparative Examples A to D, the chemical composition of magnesium hydroxide particles (magnesium hydroxide purity, impurities (Cl, SO ₄ , Cr, Ni, Ti, Mn, Mo, Fe, Zn, Al, Table 2 shows the contents of Cd, Co, Pb, and Zr)), presence / absence of surface treatment, evaluation of the combustibility of the resin composition, and evaluation of the dispersion state in the molded product.

Examples 11 to 17 and Comparative Examples E to H (magnesium oxide particles)
Example 11
100 g of the dried magnesium hydroxide particles obtained in Example 3 was put into a 300 ml alumina crucible, and particles fired at 500 ° C. for 2 hours using an electric furnace were obtained. As a result of analysis by X-ray diffraction, the obtained particles were magnesium oxide (MgO) (FIG. 13).
Example 12
Magnesium oxide particles were obtained in the same manner as in Example 11 except that the firing temperature was changed to 650 ° C.
Example 13
Magnesium oxide particles were obtained in the same manner as in Example 11 except that the firing temperature was changed to 700 ° C.
Example 14
100 g of the dried magnesium hydroxide particles obtained in Example 4 was put into a 300 ml alumina crucible and baked at 500 ° C. for 2 hours using an electric furnace to obtain magnesium oxide particles.
Example 15
Magnesium oxide particles were obtained in the same manner as in Example 14 except that the firing temperature was changed to 650 ° C., and then surface treatment was performed with 3.0 wt% stearic acid.
Example 16
Magnesium oxide particles were obtained in the same manner as in Example 14 except that the firing temperature was changed to 700 ° C.
Example 17
100 g of the dried magnesium hydroxide particles obtained in Example 8 was put in a 300 ml alumina crucible and baked at 650 ° C. for 2 hours using an electric furnace to obtain magnesium oxide particles.
Comparative Example E
100 g of the dried magnesium hydroxide particles obtained in Comparative Example A was put into a 300 ml alumina crucible and baked at 650 ° C. for 2 hours using an electric furnace to obtain magnesium oxide particles.
Comparative Example F
Magnesium oxide particles were obtained in the same manner as in Comparative Example E, except that the dry magnesium hydroxide particles used were changed to those obtained in Comparative Example B.
Comparative Example G
Magnesium oxide particles were obtained in the same manner as in Comparative Example E, except that the dry magnesium hydroxide particles used were changed to those obtained in Comparative Example C.
Comparative Example H
Magnesium oxide particles were obtained in the same manner as in Comparative Example E except that the dry magnesium hydroxide particles used were changed to those obtained in Comparative Example D, and then surface treatment was performed with 3.0 wt% stearic acid. .
(Magnesium oxide)
The magnesium oxide particles of the present invention have a fine and uniform particle size. As can be seen from the SEM photograph (FIG. 14) and the particle size distribution (FIG. 15) of the magnesium oxide particles of the present invention (Example 11), it can be confirmed that there are no noticeable aggregates and that the particles have a fine and uniform particle size.
Regarding Examples 11 to 17 and Comparative Examples E to H, treatment conditions (raw material concentration, raw material usage, reaction rate, heat treatment temperature, heat treatment time, slurry concentration, firing temperature, firing time), and characteristics of the obtained magnesium oxide particles (BET specific surface area, particle size, presence / absence of surface treatment), vulcanized physical properties (M200, M400, M600, TB, EB, Shore A, compression set, scorch time), heat aging resistance and evaluation of dispersion state of molded product Is shown in Table 4.

Examples 18 to 22 and Comparative Examples I to M (resin compositions)
(Non-crosslinked resin composition)
Example 18
The magnesium hydroxide particles of Example 4 were surface-treated with 2% by weight of stearic acid, dried at 105 ° C. for 16 hours and further dried at 120 ° C. for 2 hours. EVA (Evaflex V421 Mitsui DuPont Polychemical Co., Ltd.) Company) Magnesium hydroxide particles 150 parts by weight with respect to 90 parts by weight, modifier α-olefin copolymer (Tuffmer MH7020) 10 parts by weight, phenolic antioxidant (IRGANOX 1010) 0.5 parts by weight And 0.5 part by weight of a sulfur-based antioxidant (DLTDP) are melt-mixed at 160 to 200 ° C. with a continuous kneading extruder (Cay Engineering Co., Ltd. KCK80 × 2-35VEX), and the extruded resin composition strand is pelletized. After cutting with a vacuum dryer (LCV-242 manufactured by Tabai Espec Co., Ltd. Dried at 60 ° C. and to produce a pellet.
The obtained pellets were kneaded at 130 to 160 ° C. for 15 minutes with a small batch kneader (manufactured by Brabender Co., Ltd.), and the pellets taken out in an oval shape were 160 with a hot press (ANSF-50HH / C). A sheet having a thickness of 1 mm was prepared at a temperature of 1 ° C.
Comparative Example I
A pellet and a sheet of the resin composition were obtained in the same manner as in Example 18 except that the magnesium hydroxide particles used were changed to the magnesium hydroxide particles of Comparative Example A.
Comparative Example J
Preparation of magnesium hydroxide particles having an MV of 4.31 μm, a D ₅₀ / MV of 0.86, and a BET specific surface area of 30 m ² / g in advance, except that the magnesium hydroxide particles used are changed to the magnesium hydroxide particles described above. Were the same as in Example 18 to obtain pellets and sheets of the resin composition.
(Peroxide-crosslinked resin composition)
Example 19
The magnesium hydroxide particles of Example 4 were surface-treated with 2% by weight of stearic acid, dried at 105 ° C. for 16 hours and further dried at 120 ° C. for 2 hours. EVA (Evaflex V421 Mitsui DuPont Polychemical Co., Ltd.) Company) Magnesium hydroxide particles 150 parts by weight with respect to 90 parts by weight, modifier α-olefin copolymer (Tuffmer MH7020) 10 parts by weight, phenolic antioxidant (IRGANOX 1010) 0.5 parts by weight And 0.5 part by weight of a sulfur-based antioxidant (DLTDP) were melt-mixed at 160 to 200 ° C. with a continuous kneading extruder, the extruded resin composition strand was cut with a pelletizer, and then 60 ° C. with a vacuum dryer. And dried to prepare pellets.
The obtained pellets were blended with 1 part by weight of peroxide (DCP) per 100 parts by weight of the resin component (total of 90 parts by weight of EVA and 10 parts by weight of the modifier α-olefin copolymer). The mixture was melt-mixed at 115 ° C. for 10 minutes, taken out in an oval shape, formed into a thickness of 2 mm at 120 ° C. by a hot press, and a crosslinked sheet having a thickness of 1 mm at 180 ° C. was obtained.
Comparative Example K
Resin composition pellets and a crosslinked sheet were obtained in the same manner as in Example 19 except that the magnesium hydroxide particles used were changed to the magnesium hydroxide particles of Comparative Example A.
Comparative Example L
Preparation of magnesium hydroxide particles having an MV of 4.31 μm, a D ₅₀ / MV of 0.86, and a BET specific surface area of 30 m ² / g in advance, except that the magnesium hydroxide particles used are changed to the magnesium hydroxide particles described above. Obtained a resin composition pellet and a crosslinked sheet in the same manner as in Example 19.
(Silane-crosslinked resin composition)
Example 20
The magnesium hydroxide particles of Example 5 were surface-treated with 0.3% by weight of a silane coupling agent, dried at 105 ° C. for 16 hours, and further dried at 120 ° C. for 2 hours to obtain a silane crosslinkable EVA resin (link). Ron XVF600N (Mitsubishi Chemical Corporation) 135 parts by weight of magnesium hydroxide particles subjected to the above treatment with respect to 87 parts by weight, 10 parts by weight of a modifier α-olefin copolymer (Tuffmer MH7020), phenolic antioxidant (IRGANOX1010) 0.5 parts by weight and 0.5 parts by weight of a sulfur-based antioxidant (DLTDP) were mixed and melted at 160 to 200 ° C. by a small batch kneader to prepare an oval resin composition.
The obtained oval resin composition had a resin component of 97 parts by weight (a total of 87 parts by weight of a silane crosslinkable EVA resin and 10 parts by weight of a modifier α-olefin copolymer) and 3 parts by weight of a crosslinking acceleration catalyst masterbatch. The mixture was melted and mixed at 180 ° C. for 10 minutes with a small batch kneader, and again taken out in an oval shape, formed into a thickness of 2 mm at 160 ° C. and further formed into a thickness of 1 mm at 180 ° C. The molded resin composition was immersed in ion exchange water at 80 ° C. for 24 hours to obtain a crosslinked sheet.
Example 21
Magnesium hydroxide particles to be used were changed to the magnesium hydroxide particles of Example 4, and a cross-linked sheet was obtained in the same manner as in Example 20 except that the blending amount was changed to 140 parts.
Example 22
A crosslinked sheet was obtained in the same manner as in Example 20 except that the magnesium hydroxide particles used were changed to the magnesium hydroxide particles of Example 4.
Comparative Example M
Prepare magnesium hydroxide particles having an MV of 0.87 μm, a D50 / MV of 0.83, and a BET specific surface area of 6 m 2 / g in advance. A crosslinked sheet was obtained in the same manner as in Example 20 except that the amount was changed to 140 parts.
Comparative Example N
A crosslinked sheet was obtained in the same manner as in Comparative Example M, except that the amount of magnesium hydroxide particles used was changed to 150 parts.
Table 5 shows the evaluation of fluidity, colorability and tensile properties of the resin compositions for Examples 18 to 19 and Comparative Examples I to L.
Table 6 shows the evaluation of the tensile properties and the flammability of the resin compositions for Examples 20 to 22 and Comparative Examples M to N.

(Resin composition)
Since the magnesium hydroxide particles of the present invention are fine particles of uniform size, the resin composition containing them is characterized by very little discoloration (yellowing) (Examples 18 and 19). On the other hand, conventional resin compositions containing fine but irregular magnesium hydroxide particles have more discoloration (yellowing) than the resin composition of the present invention (Comparative Examples I, J, K, and L).
The resin composition of the present invention has good MFR (melt flow rate) correlated with extrusion processability (Example 18), and also has excellent flame retardancy and tensile properties (Examples 20 and 21). ).
Effects of the Invention According to the production method of the present invention, magnesium hydroxide particles having a fine and uniform particle diameter, high purity, and excellent dispersibility can be produced. Since the production method of the present invention is heat-treated at a low temperature of 0 to 100 ° C., the obtained magnesium hydroxide particles have a characteristic that the crystal structure is thermodynamically unstable. Therefore, impurities such as metals such as Cl ions, SO ₄ ions, nickel, chromium, lead, zinc, and aluminum can be easily removed from the product in the water washing step.
In addition, the magnesium hydroxide particles of the present invention have a fine and uniform particle diameter, are highly pure, and are excellent in dispersibility. Since the magnesium hydroxide particles of the present invention are manufactured by heat treatment at a low temperature of 0 to 100 ° C., the crystal structure is thermodynamically unstable and OH is released compared with magnesium hydroxide heat-treated at a higher temperature. The temperature is low. Therefore, it is excellent in flame retardancy. The magnesium hydroxide particles of the present invention have a low content of metals such as Cl ions, SO ₄ ions, nickel, chromium, lead, zinc, and aluminum. Further, the magnesium hydroxide particles of the present invention can achieve uniform kneading or uniform coating treatment in applications to organic polymer materials and inorganic materials.
In addition, the magnesium oxide particles of the present invention have a fine and uniform particle size, high purity, and excellent dispersibility. The magnesium oxide particles of the present invention have a low content of nickel, chromium, lead, zinc, and aluminum. Moreover, the magnesium oxide particle of this invention can implement | achieve uniform kneading | mixing or a uniform coating process in the use to an organic polymer material or an inorganic material.

The magnesium hydroxide particles of the present invention are useful as a flame retardant for polymer materials and an inorganic filler for separators for non-aqueous secondary batteries. The magnesium oxide particles of the present invention are useful as an acid acceptor for organic polymer materials, a deodorant, an electromagnetic steel material, a resin filler, a catalyst, a catalyst carrier, and the like.
Furthermore, since the magnesium hydroxide and magnesium oxide particles of the present invention have a small amount of nickel, chromium, lead, zinc, and aluminum, they can be used as additives for electronic materials, pharmaceutical raw materials, and food and beverage products. It can also be used as a synthetic raw material for cosmetics, foods, pharmaceutical pH adjusters, polymer stabilizers, fine particle hydrotalcite, and the like.

Claims

(I) reacting an aqueous solution of a soluble magnesium salt with an aqueous alkali solution to produce a slurry containing magnesium hydroxide particles,
(Ii) The obtained slurry was heat-treated at 0 to 100 ° C. under atmospheric pressure for 5 to 500 hours,
(Iii) separating and purifying the cake containing magnesium hydroxide particles from the heat-treated slurry, and (iv) drying the separated and purified cake to obtain magnesium hydroxide particles.
The manufacturing method of the magnesium hydroxide particle | grains including each process.
The production method according to claim 1, wherein the soluble magnesium salt is magnesium chloride or magnesium sulfate.
The production method according to claim 1, wherein the alkaline aqueous solution is an aqueous solution of sodium hydroxide.
The production method according to claim 1, wherein a soluble magnesium salt of 0.1 to 5.7 mol / L is reacted with an alkaline aqueous solution of 1.0 to 18.0 N.
The resulting magnesium hydroxide particles are
(A) The average secondary particle size (MV) is 50 to 800 nm,
(B) D 50 / MV is 0.70 to 0.99, where D 50 is a volume-based cumulative 50% particle diameter by laser diffraction scattering particle size distribution measurement,
(C) The OH desorption temperature in thermogravimetric analysis when heated at 10 ° C./min in an air atmosphere is 360 to 388 ° C.,
The manufacturing method according to claim 1.
(A) The average secondary particle size (MV) is 50 to 800 nm,
(B) D 50 / MV is 0.70 to 0.99, where D 50 is a volume-based cumulative 50% particle diameter by laser diffraction scattering particle size distribution measurement,
(C) The OH desorption temperature in thermogravimetric analysis when heated at 10 ° C./min in an air atmosphere is 360 to 388 ° C.,
Magnesium hydroxide particles characterized by the above.
The magnesium hydroxide particles according to claim 6, wherein the content of Cl ions is 50 to 300 ppm.
The magnesium hydroxide particles according to claim 6, wherein the content of SO 4 ions is 50 to 300 ppm.
The magnesium hydroxide particles according to claim 6, wherein the BET specific surface area is 8.0 to 280 m 2 / g.
Magnesium hydroxide particles according to claim 6, having a purity of 99.5 wt% or more.
The magnesium hydroxide particles according to claim 6, wherein the total content of Cr, Ni, Ti, Mn, Mo, Fe, Zn, Al, Cd, Co, Pb and Zr is 10 to 150 ppm.
Magnesium oxide particles obtained by firing the magnesium hydroxide particles according to claim 6 at 350 to 1200 ° C.
A resin composition comprising 100 parts by weight of synthetic resin and 0.01 to 350 parts by weight of magnesium hydroxide particles according to claim 6.
A resin composition comprising 100 parts by weight of a synthetic resin and 0.01 to 350 parts by weight of the magnesium oxide particles according to claim 12.