TWI600617B - Rod-like magnesium hydroxide particle and magnesium oxide particle with high specific surface area, and manufacturing method thereof - Google Patents

Description

Rod-shaped magnesium hydroxide particles having high specific surface area and rod-shaped magnesium oxide particles, and manufacturing method thereof

The present invention relates to a rod-shaped magnesium hydroxide particle having a high specific surface area and a rod-shaped magnesium oxide particle, and a process for producing the same.

Magnesium hydroxide particles and magnesium oxide particles are used in a wide variety of fields. Examples of the use of the magnesium hydroxide particles include a coating agent for an inkjet paper, a flame retardant, a heat storage material, a catalyst, and an electronic material. Examples of the use of the magnesium oxide particles include application of an optical material or inkjet paper. Agents, catalysts and electronic materials.

When the magnesium hydroxide particles are used in a coating agent for an inkjet paper, a flame retardant, a heat storage material, a catalyst, and an electronic material, the following cases are expected. In the coating agent, the magnesium hydroxide particles are required to have an OH group having a high affinity with many OH groups possessed by the dye ink and a positive charge which is easily adsorbed on a pigment ink having a large number of negative charges, and has a dye which is easily penetrated into the ink. Condensed structure between particles. Further, in the flame retardant, the heat storage material, and the catalyst, the magnesium hydroxide particles are required to have excellent dispersibility and have an aggregate structure exhibiting high reactivity. Further, in the electronic material, fine magnesium hydroxide particles excellent in dispersibility are required.

When the magnesium oxide particles are used in applications such as an optical material, a coating agent for inkjet paper, a catalyst, and an electronic material, the following cases are expected. In the optical material, the magnesium oxide particles are required to have excellent dispersibility and have an aggregate structure that easily diffuses light. Further, in the catalyst, the magnesium oxide particles are required to have excellent dispersibility and have an aggregate structure exhibiting high reactivity. Further, in the electronic material, fine magnesium oxide particles excellent in dispersibility are required.

Patent Document 1 describes a spherical magnesium hydroxide particle having a structure in which two or more leaf-like pieces in different directions are combined and/or intersected, by using a sulfate ion [(SO4) ^2- ]/magnesium ion The ion concentration ratio of [(Mg) ²⁺ ] is obtained in a range of 0.3 to 2.0. However, in the method described in Patent Document 1, spherical magnesium hydroxide cannot be stably produced and is doped with plate-like and columnar magnesium hydroxide, and the dispersibility of the magnesium hydroxide particles to a resin or the like is When it is used insufficiently in a catalyst or the like, it has a problem that the specific surface area is low and the reactivity is low.

Prior technical literature Patent literature

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-261796

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnesium hydroxide particle and a magnesium oxide particle having a high specific surface area, and a process for producing the same.

The present inventors have found that a dispersion selected from a compound containing one or more compounds selected from the group consisting of Zn, Zr, Hf, and Ti is added and selected from the group consisting of One or more compounds consisting of a chloride of a divalent or trivalent metal element and a nitrate of a divalent or trivalent metal element (except for compounds of Zn, Zr, Hf, and Ti), Further, the reaction liquid obtained by further adding an organic acid is mixed with acicular magnesium oxide particles obtained by partially hydrating the surface of the acicular magnesium oxide particles using a constant temperature and humidity machine, and is subjected to hydration reaction under high shear. It is possible to obtain magnesium hydroxide particles having excellent dispersibility, high reactivity, and high specific surface area. Further, the inventors of the present invention have found that magnesium oxide particles having a high specific surface area can be obtained by calcining the magnesium hydroxide particles of the present invention in an air atmosphere at 500 ° C to 1400 ° C.

That is, the present invention relates to a rod shape in which scaly primary particles are agglomerated, and a volume cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction scattering particle size distribution is 1.0 to 10.0 μm. A magnesium hydroxide particle having a specific surface area of 10 m ² /g or more.

The present invention relates to a magnesium hydroxide particle according to the above aspect, which further contains 0.1 to 5.0% by mass of one or more selected from the group consisting of Zn, Zr, Hf, and Ti in terms of a metal element. The metal element and the metal element are further contained in an amount of 0.1 to 5.0% by mass based on one or more metal elements selected from the group consisting of divalent and trivalent metal elements (however, Zn, Zr, Hf, and Ti systems) except).

The present invention relates to a rod shape in which scaly primary particles are agglomerated, and the volume cumulative 50% particle diameter (D ₅₀ ) measured by laser diffraction scattering particle size distribution is 1.0 to 10.0 μm, and the specific surface area is Magnesium oxide particles of 10 m ² /g or more.

The present invention relates to a magnesium oxide particle according to the above aspect, which further contains 0.1 to 5.0% by mass, based on the metal element, selected from the group consisting of Zn, Zr, Hf, And one or more metal elements of the group consisting of Ti and further containing 0.1 to 5.0% by mass of a metal element selected from the group consisting of divalent and trivalent metal elements in terms of a metal element ( However, except for Zn, Zr, Hf, and Ti).

The present invention relates to a method for producing magnesium hydroxide particles, which comprises: (a) one or more groups containing a compound selected from the group consisting of Zn, Zr, Hf, and Ti One or more compounds selected from the group consisting of chlorides of divalent and trivalent metal elements and nitrates of divalent and trivalent metal elements are added to the dispersion of the compound (however, Zn, Zr, Hf, And a compound of Ti), a step of further adding an organic acid to obtain a reaction liquid; (b) 50% of the volume of the reaction liquid of the step (a) and the volume measured by a laser diffraction scattering particle size distribution a step (D ₅₀ ) of 0.1 to 10 μm, a specific surface area of 1.0 to 20.0 m ² /g, and an Ig-loss of 2.0 to 25.0% of a partially hydrated acicular magnesium oxide to obtain a mixed liquid; (here, selected from One or more compounds of the group consisting of a compound of Zn, Zr, Hf, and Ti are 0.1 to 5.0% by mass based on a part of the hydrated acicular magnesium oxide in terms of a metal element; and are selected from the group consisting of 2 and 3 a group of chlorides of metal elements and nitrates of divalent and trivalent metal elements The compound of the group or more is 0.1 to 5.0% by mass based on a part of the hydrated acicular magnesium oxide, and the organic acid is 0.01 to 3.0 mol per 100 g of the hydrated acicular magnesium oxide; (c) mixing the mixture of step (b) at a temperature of 50 to 100 ° C using a mixer having a peripheral speed of 7 to 20 m/s; (d) stirring at a temperature of 30 to 100 ° C to obtain hydrogen a step of obtaining a magnesium oxide slurry; and (e) a step of filtering the magnesium hydroxide slurry of the step (d), washing with water, and drying to obtain magnesium hydroxide particles.

The present invention relates to a method as described above, wherein a part of the hydrated acicular magnesium oxide of step (b) is a 50% particle size (D _{50 ) which} is accumulated by a volume of a laser diffraction scattering particle size distribution. An acicular magnesium oxide particle having a specific surface area of 1.0 to 15.0 m ² /g, which is 0.1 to 10 μm, is placed in a constant temperature and humidity machine at a temperature of 40 to 95 ° C and a humidity of 60 to 95% for 0.5 to 24 hours. get.

The present invention relates to a method as described above, wherein a concentration of a portion of the hydrated acicular magnesium oxide in the mixed liquid of the step (b) is from 20 to 200 g/L.

The present invention relates to a method for producing magnesium oxide particles, which comprises the magnesium hydroxide particles as described above or magnesium hydroxide particles obtained according to the method described above, in an atmospheric environment. The calcination step is carried out at 500 to 1400 °C.

According to the present invention, it is possible to provide rod-shaped magnesium hydroxide particles and magnesium oxide particles in which scaly primary particles having a high specific surface area are aggregated, and a method for producing the same. The magnesium hydroxide particles and the magnesium oxide particles of the present invention have high specific surface area and dispersibility, and are useful in various fields. Moreover, according to the production method of the present invention, magnesium hydroxide particles and magnesium oxide particles having high specific surface area and dispersibility can be easily produced.

Fig. 1 is an electron micrograph of the magnesium hydroxide particles of the present invention. Use white An example of a circular frame of primary particles.

The magnesium hydroxide particles of the present invention have a rod-like shape in which scaly primary particles are aggregated, and a volume cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction scattering particle size distribution is 1.0 to 10.0 μm, specific surface area. It is 10 m ² /g or more.

The shape of the primary particles of the present invention is scaly. An example of a scale is shown in Fig. 1. The scaly primary particles of the present invention have a thickness of 0.01 to 0.1 μm, preferably 0.01 to 0.05 μm, and the diameter of the circumscribed circle of the surface is in the range of 0.2 to 5 μm, preferably 0.5 to 2.5 μm.

In the present specification, the rod shape refers to particles in which scaly primary particles are aggregated and the aspect ratio (particle length L / particle cross-sectional diameter D) is from 1.5 to 20, preferably from 2 to 10. Here, in the case of a rod shape, specifically, it is in the range of 1 to 10 μm and D is 0.1 to 5 μm. Further, the needle-like shape means particles having an aspect ratio (particle length L / particle cross-sectional diameter D) of from 21 to 1,000, preferably from 50 to 500. Here, in the case of a needle, specifically, it means that L is 0.1 to 10 μm, and D is specifically in the range of 0.001 to 0.5 μm. Further, the spherical shape and the scaly primary particles are aggregated in a spherical shape and the aspect ratio (particle length L / particle cross-sectional diameter D) is in the range of 1.0 to 1.2. Here, in the case of a spherical shape, the L system is specifically 1 to 20 μm, and the D system is specifically in the range of 1 to 20 μm.

The rod-like particles obtained by agglomerating such primary particles are present in a fine pore system having a uniform surface on the surface of the particles, and are compared with the hexagonal plate-shaped magnesium hydroxide particles obtained according to the prior production method (Japanese Unexamined Patent Publication No. Hei No. 2006-306658) Reference), since the specific surface area is high, the adsorption of liquid and gas molecules is high. Moreover, when the rod-shaped particles obtained by agglomerating such primary particles are used as a coating agent for paper, they are constituted by rod-shaped particles. The scaly magnesium hydroxide is not too dense, so the ink has good adsorptivity.

The magnesium hydroxide particles of the present invention have a rod-like shape in which scaly primary particles are aggregated, and a volume cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction scattering particle size distribution is 1.0 to 10.0 μm, specific surface area. It is 10 m ² /g or more. In such a range, when the resin or the like is blended, the viscosity is not too high, and since the aggregation of the particles can be suppressed, the dispersibility is good. Moreover, when the magnesium hydroxide particle having such a particle diameter is used as a coating agent for paper, the fixability and absorbability of the ink are good. Moreover, since the particle diameter is not too large, it is useful in optical materials and electronic materials. The 50% particle diameter (D ₅₀ ) of the volume cumulative of the magnesium hydroxide particles of the present invention as measured by the laser diffraction scattering particle size distribution is preferably 2.0 to 9.0 μm, preferably 3.0 to 8.0 μm. The surface area is preferably from 10 to 200 m ² /g, preferably from 20 to 150 m ² /g. In the present invention, the specific surface area can be determined by the BET method.

The magnesium hydroxide particles of the present invention have a ratio of cumulative 10% particle diameter (D ₁₀ ) to cumulative 90% particle diameter (D ₉₀ ) by volume ratio of the laser diffraction scattering particle size distribution D ₉₀ /D ₁₀ It is preferably 10 or less, preferably 1 to 8. In such a case of D ₉₀ /D ₁₀ , since the particle size distribution of the magnesium hydroxide particles is narrow and the aggregation of the particles is small, more excellent dispersibility can be obtained.

The magnesium hydroxide particles of the present invention may further contain a metal element of the compound used in the production step. The magnesium hydroxide particles of the present invention may contain 0.1 to 5.0% by mass of a metal element selected from the group consisting of Zn, Zr, Hf, and Ti in terms of a metal element; Further, it may further contain 0.1 to 5.0% by mass of one or more metal elements selected from the group consisting of divalent and trivalent metal elements (except for Zn, Zr, Hf, and Ti systems). When the content of the metal elements is used, the magnesium hydroxide particles are used as a coating agent. The whiteness, the ultraviolet absorbing property, and the refractive index are sufficient. The content of one or more metal elements selected from the group consisting of Zn, Zr, Hf, and Ti, that is, Zn, Zr, Hf, Ti, or the like, is 0.2 to 0.1 in terms of metal element 4.0% by mass is preferred, and preferably 0.3 to 3.0% by mass.

In the present invention, one or more metal elements (excluding Zn, Zr, Hf, and Ti) selected from the group consisting of divalent and trivalent metal elements are not particularly limited, and are not particularly limited. Examples thereof include Ag, Al, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, In, Mn, Mo, Ni, Pb, Sr, Tl, and V, and preferably Al and Fe. The content of one or more metal elements (excluding Zn, Zr, Hf, and Ti) in a group consisting of a divalent or trivalent metal element is 0.1 to 5.0% by mass in terms of a metal element. It is preferably 0.2 to 4.0% by mass, preferably 0.3 to 3.0% by mass.

The magnesium oxide particles of the present invention have a rod-like shape in which scaly primary particles are aggregated, and a volume cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction scattering particle size distribution is 1.0 to 10.0 μm, and a specific surface area is 10m ² /g or more. The shape of the primary particles of the present invention is scaly, and is the same as the example of the scaly shape of Fig. 1. The scaly primary particle system of the present invention has a thickness of 0.01 to 0.1 μm, preferably 0.01 to 0.05 μm, and the diameter of the circumscribed circle of the surface is 0.2 to 5 μm, preferably 0.5 to 2.5 μm. Such magnesium oxide particles are excellent in dispersibility in a resin or the like. Specifically, when the magnesium oxide particles having such a particle diameter and a specific surface area are used as a coating agent for paper, the ink has good fixability and absorbability. Further, since the viscosity is not too high when the resin or the like is blended, and the aggregation of the particles can be suppressed, the dispersibility is good. Moreover, since the particle diameter is not too large, it is useful in optical materials and electronic materials. The 50% particle diameter (D ₅₀ ) of the volume cumulative of the magnesium oxide particles of the present invention as determined by laser diffraction scattering particle size distribution is preferably 2.0 to 9.0 μm, preferably 3.0 to 8.0 μm, specific surface area. It is preferably 10 to 200 m ² /g, more preferably 20 to 150 m ² /g.

The magnesium oxide particles of the present invention have a ratio of a cumulative 10% particle diameter (D ₁₀ ) to a cumulative 90% particle diameter (D ₉₀ ) by a volume ratio of the laser diffraction scattering particle size distribution D ₉₀ /D ₁₀ , It is preferably 10 or less, preferably 1 to 8. When such a ratio D ₉₀ /D ₁₀ is obtained, since the particle size distribution of the magnesium oxide particles is narrow and the aggregation of the particles is small, more excellent dispersibility can be obtained.

The magnesium oxide particles of the present invention may further contain a metal element of the compound used in the production step. The magnesium oxide particles of the present invention are contained in an amount of 0.1 to 5.0% by mass, based on the metal element, of at least one metal element selected from the group consisting of Zn, Zr, Hf, and Ti; Further, one or more metal elements selected from the group consisting of divalent and trivalent metal elements (excluding Zn, Zr, Hf, and Ti) are further contained. When the content of the metal element is used, when the magnesium oxide particles are used as a coating agent, the whiteness, the ultraviolet absorbing property, the refractive index, and the like are sufficient. The content of one or more metal elements, that is, Zn, Zr, Hf, Ti, or a mixture thereof, which is a group consisting of Zn, Zr, Hf, and Ti, is 0.2 to 0.1 in terms of metal element 4.0% by mass is preferred, and preferably 0.3 to 3.0% by mass.

Further, one or more metal elements (excluding Zn, Zr, Hf, and Ti) which are further selected from the group consisting of divalent and trivalent metal elements are not particularly limited, and examples thereof include Ag, Al, and B. , Ba, Bi, Cd, Co, Cr, Cu, Fe, Ga, In, Mn, Mo, Ni, Pb, Sr, Tl and V, preferably Al and Fe. Further, the content of one or more metal elements (excluding Zn, Zr, Hf, and Ti) selected from the group consisting of divalent and trivalent metal elements is converted into a metal element. It is preferably 0.2 to 4.0% by mass, preferably 0.3 to 3.0% by mass.

The method for producing magnesium hydroxide particles according to the present invention comprises: (a) a dispersion liquid containing one or more compounds selected from the group consisting of compounds of Zn, Zr, Hf, and Ti, and is selected from the group consisting of And one or more compounds of a group consisting of a chloride of a trivalent metal element and a nitrate of a divalent or trivalent metal element (except for a compound of Zn, Zr, Hf, and Ti), and further adding an organic compound a step of obtaining a reaction liquid by acid; (b) a 50% particle diameter (D ₅₀ ) of the reaction liquid of the step (a) and a volume measured by a laser diffraction scattering particle size distribution of 0.1 to 10 μm, ratio a step of mixing a portion of the hydrated acicular magnesium oxide having a surface area of 1.0 to 20.0 m ² /g and an Ig-loss of 2.0 to 25.0% to obtain a mixed solution; (here, a compound selected from the group consisting of Zn, Zr, Hf, and Ti) One or more compounds of the group are 0.1 to 5.0% by mass based on a part of the hydrated acicular magnesium oxide in terms of a metal element; a chloride selected from a divalent and trivalent metal element, and 2 and 3 One or more compounds of a group consisting of nitrates of a valence metal element, exchanged for metal elements The amount is 0.1 to 5.0% by mass based on a part of the hydrated acicular magnesium oxide; the organic acid is 0.01 to 3.0 mol based on 100 g of the partially hydrated acicular magnesium oxide; (c) the mixture of the step (b) is a step of mixing at a temperature of 50 to 100 ° C using a mixer having a peripheral speed of 7 to 20 m/s; (d) a step of obtaining a magnesium hydroxide slurry by stirring at a temperature of 30 to 100 ° C; and (e) The magnesium hydroxide slurry of the step (d) is filtered, washed with water and dried to obtain magnesium hydroxide particles.

Step (a) is a step of obtaining a part of magnesium hydroxide for the reaction liquid of the hydration reaction.

One or more compounds selected from the group consisting of Zn, Zr, Hf, and Ti are added to produce magnesium hydroxide particles and magnesium oxide particles of the present invention. Thereby, it is possible to obtain magnesium hydroxide and magnesium oxide particles of the present invention which are suitable for coating materials for optical materials and inkjet papers, such as improvement in whiteness, ultraviolet absorbing property, and refractive index.

The compound of Zn, Zr, Hf, and Ti is not particularly limited as long as it has a compound having such a metal element, and examples thereof include an oxide, a hydroxide, a hydride, and a halide (fluoride, chloride, and bromine). Compounds, and iodides), phosphates, carbonates, and nitrates, such as zinc oxide, zinc hydroxide, zinc chloride, zinc nitrate, zirconium oxide, zirconium hydroxide, zirconium chloride, zirconium nitrate, cerium oxide, Barium hydroxide, barium chloride, barium nitrate, titanium oxide, titanium hydroxide, titanium chloride, and titanium nitrate are preferred.

The purity of the compound of Zn, Zr, Hf, and Ti is preferably 99.0% or more, and more preferably 99.5% or more. In the present invention, the purity is determined as an impurity element (Ag, Al, B, Ba, Bi, Ca, Cd, Cl, Co, Cr, Cu, Fe, Ga, in the compounds of Zn, Zr, Hf, and Ti). The content of Hf, In, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Si, Sr, Ti, Tl, V, Zn, and Zr) is subtracted from 100% by mass. The value after the total content.

Further, when the element of the compound itself of Zn, Zr, Hf, and Ti constituting the object is an impurity element corresponding to the compound of Zn, Zr, Hf, and Ti, the element is not contained in the impurity element. For example, when the compound of Zn, Zr, Hf, and Ti used in the step (a) is ZnO, Zn which constitutes ZnO is not included in the foregoing. An impurity element in a compound of Zn, Zr, Hf, and Ti. As a method of measuring the content of such an impurity element, a measurement method using an ICP emission spectrometer is exemplified.

The D ₅₀ of the compound of Zn, Zr, Hf, and Ti is preferably 0.1 to 100 μm, more preferably 0.5 to 50 μm.

The solvent of the dispersion liquid containing one or more types of compounds selected from the group consisting of Zn, Zr, Hf, and Ti may be ion-exchanged water. The dispersion liquid used in the step (a) can be obtained, for example, by adding one or more compounds selected from the group consisting of Zn, Zr, Hf, and Ti in ion-exchanged water.

The chloride of the divalent and trivalent metal elements and the nitrate of the divalent and trivalent metal elements used in the step (a) are added for controlling the solubility and the precipitation rate of the magnesium hydroxide particles of the present invention. The chlorides of the divalent and trivalent metal elements, and the nitrates of the divalent and trivalent metal elements are preferably aluminum chloride, iron chloride, aluminum nitrate, and iron nitrate. The chloride of the divalent or trivalent metal element and the nitrate of the divalent or trivalent metal element preferably have a purity of 99.0% or more, and preferably 99.5% or more. Further, the chloride of the divalent and trivalent metal elements and the nitrate of the divalent and trivalent metal elements preferably have a D ₅₀ of from 0.1 to 100 μm, preferably from 0.5 to 50 μm.

In the present invention, the organic acid is added in order to suppress the solubility of a part of the raw material hydrated acicular magnesium oxide. The organic acid may, for example, be an aliphatic or aromatic organic acid having a carboxyl group, and preferably contains formic acid, acetic acid, propionic acid, butyric acid, and benzoic acid.

The step (b) is a step of mixing the reaction liquid for the hydration reaction obtained in the step (a) and a part of the hydrated acicular magnesium oxide particles. a portion of the hydrated acicular magnesium oxide particles used in the step (b), wherein the volume cumulative 50% particle diameter (D ₅₀ ) determined by the laser diffraction scattering particle size distribution is 0.1 to 10 μm, and the specific surface area is 1.0 to 20.0 m ² /g, Ig-loss is 2.0 to 25.0% of a part of the surface of the acicular magnesium oxide which is hydrated, that is, acicular magnesium oxide which is partially hydrated. By using such a part of hydrated acicular magnesium oxide, it is possible to obtain rod-shaped magnesium hydroxide particles in which scaly primary particles having a high specific surface area are aggregated.

When a part of the hydrated acicular magnesium oxide particles used in the step (b) has a volume cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction scattering particle size distribution of less than 0.1 μm, the hydration speed becomes Too fast to become coarse aggregated particles. Further, when D _{50 is} more than 10 μm, the hydration reaction system does not sufficiently proceed to leave particles containing magnesium oxide. The D ₅₀ system is preferably 0.1 to 5.0 μm.

When one of the partially hydrated acicular magnesium oxide particles used in the step (b) has a specific surface area of more than 20.0 m ² /g, the hydration rate becomes too fast to become coarse aggregated particles. Further, when the specific surface area is less than 1.0 m ² /g, the hydration reaction system does not sufficiently proceed to leave particles containing magnesium oxide. The specific surface area is preferably 2.0 to 18.0 m ² /g, and more preferably 3.0 to 15.0 m ² /g.

The partially hydrated acicular magnesium oxide particles used in the step (b) have an Ig-loss (ignition loss) of 2.0 to 25.0% (mass conversion) in terms of the total amount of moisture attached to the hydrate structure. That is, the Ig-loss system indicates the degree of hydration of the hydrated acicular magnesium oxide particles in one part of the present invention. When the Ig-loss is less than 2.0%, the hydration speed tends to become uneven, and it becomes an amorphous coarse aggregated particle having a small specific surface area. When the Ig-loss is more than 25.0%, the hydration reaction is suppressed, and the acicular magnesium oxide which remains unhydrated remains and becomes coarse aggregated particles, which is not preferable. In order to allow the hydration reaction to proceed sufficiently, and to obtain a rod-shaped magnesium hydroxide having a high specific surface area, Ig-loss It is preferably 2.0 to 20.0%, more preferably 3.0 to 18.0%. In the present invention, the Ig-loss system can be obtained by measuring a part of the hydrated acicular magnesium oxide particles after calcination at 1000 ° C for 3,600 seconds.

The partially hydrated acicular magnesium oxide used in the step (b) is capable of accumulating a 50% particle diameter (D ₅₀ ) of a volume measured by a laser diffraction scattering particle size distribution of 0.1 to 10 μm, specific surface area. The acicular magnesium oxide particles of 1.0 to 15.0 m ² /g are obtained by placing in a constant temperature and humidity machine at a temperature of 40 to 95 ° C and a humidity of 60 to 95% for 0.5 to 24 hours. Usually, the Ig-loss of the acicular magnesium oxide of the raw material is 0.1 to 1.0%, but the Ig-loss can be increased by increasing the temperature and time placed in the constant temperature and humidity machine.

The acicular magnesium oxide of the raw material of the hydrated acicular magnesium oxide used in the step (b) preferably has a D ₅₀ system of 0.1 to 5.0 μm.

Further, the acicular magnesium oxide of the raw material of the hydrated acicular magnesium oxide prepared in the step (b) preferably has a specific surface area of from 0 to 15.0 m ² /g, preferably 3.0 to 15.0 m ² /g. .

The acicular magnesium oxide which is a raw material for hydrating acicular magnesium oxide used in the step (b) is not particularly limited, and for example, acicular magnesium carbonate prepared by reacting magnesium sulfate with sodium carbonate can be purified. And obtained by calcination at 1200 ° C.

The amount of each component contained in the partially hydrated acicular magnesium oxide and the dispersion used in the step (b) is as follows.

The amount of one or more compounds selected from the group consisting of Zn, Zr, Hf, and Ti is 0.1 to 5.0% by mass in terms of a metal element, relative to a part of the hydrated acicular magnesium oxide particles. The amount of the compound selected from the group consisting of compounds of Zn, Zr, Hf, and Ti is less than 0.1% by mass, and is used as a coating agent. In the meantime, the whiteness, the ultraviolet absorbing property, the refractive index, and the like are insufficient, and the particle shape is not a rod-like particle in which the scaly primary particles are aggregated, but is a hexagonal plate-like particle. Further, when the amount of the compound selected from the group consisting of compounds of Zn, Zr, Hf, and Ti is more than 5.0% by mass, the rod-like particles obtained by condensing the scaly primary particles of the present invention are not hexagonal columns. Shaped particles. The amount of one or more compounds selected from the group consisting of compounds of Zn, Zr, Hf, and Ti is preferably 0.2 to 4.0% by mass, preferably 0.3 to hydrated acicular magnesium oxide particles. 3.0% by mass.

The amount of one or more compounds selected from the group consisting of chlorides of divalent and trivalent metal elements and nitrates of divalent and trivalent metal elements is a metal based on a part of the hydrated acicular magnesium oxide particles. The element conversion is 0.1 to 5.0% by mass. When the amount of addition is less than 0.1% by mass, the precipitation rate of the crystal becomes slow and becomes monodisperse hexagonal columnar particles. When the amount is more than 5.0% by mass, the precipitation rate of the crystal becomes too fast to become coarse aggregated particles. The amount of one or more compounds selected from the group consisting of chlorides of divalent and trivalent metal elements and nitrates of divalent and trivalent metal elements with respect to a part of the hydrated acicular magnesium oxide particles The element conversion meter is preferably 0.2 to 4.0% by mass, preferably 0.3 to 3.0% by mass.

The organic acid is added in an amount of 0.01 to 3.0 mol based on 100 g of a part of the hydrated acicular magnesium oxide particles. When the amount of the organic acid added is less than 0.01 mol with respect to a part of the hydrated acicular magnesium oxide particles, the precipitation rate of the crystal becomes slow, and the monolithic plate or hexagonal columnar particles are monodispersed. When the amount is more than 3.0 mol, the crystal is crystallized. The precipitation rate becomes too fast to become coarse aggregated particles. The organic acid is preferably added in an amount of from 0.01 to 2.0 mol based on 100 g of a part of the hydrated acicular magnesium oxide.

In the step (b), the concentration of the acicular magnesium oxide is partially hydrated in one of the mixed liquids, preferably 20 to 200 g/L, more preferably 50 to 180 g/L, still more preferably 50 to 150 g/L. That is, it is preferable to adjust the amount of a part of the hydrated acicular magnesium oxide to 20 to 200 g/L, preferably 50 to 180 g/L, more preferably 50, with respect to the reaction liquid obtained in the step (a). Up to 150g/L. When one of the reaction liquids partially hydrates the acicular magnesium oxide concentration, the hydration reaction proceeds sufficiently.

Step (c) is a step of mixing at a temperature of 50 to 100 ° C using a mixer having a peripheral speed of 7 to 20 m/s. The stirring rotation number can be adjusted to control the dispersion state at the time of the reaction.

In the present invention, when the peripheral speed is less than 7 m/s, the rod-shaped magnesium hydroxide in which the scaly primary particles are aggregated cannot be obtained. Further, when the peripheral speed is more than 20 m/s, the magnesium hydroxide particles are excessively dispersed at the time of nucleation to form a monodisperse hexagonal plate or a hexagonal columnar magnesium hydroxide particle, and the hydroxide of the present invention cannot be obtained. Magnesium particles. The apparatus for such agitation is not particularly limited as long as the above-described peripheral speed is satisfied, and a uniform disperser (PRIMIX Co., Ltd., T.K. uniform disperser) or the like can be given. The peripheral speed is preferably 8 to 18 m/s, preferably 9 to 15 m/s. The reaction temperature in the step (c) is preferably 55 to 95 ° C, preferably 60 to 95 ° C. In the step (c), the mixing time can be changed depending on the degree of the hydration reaction, for example, 10 to 360 minutes, preferably 20 to 200 minutes.

Step (d) is a step of obtaining a magnesium hydroxide slurry by stirring at a temperature of from 30 to 100 °C. Thereby, in the step (c), it is possible to promote the hydration reaction of the unreacted part of the hydrated acicular magnesium oxide to become magnesium hydroxide. The temperature is preferably from 50 to 95 ° C, preferably from 70 to 90 ° C. The stirring speed is not particularly limited as long as the magnesium hydroxide slurry can be sufficiently stirred, for example, when a mixer with three blades is used. Set to 100 to 500 rpm. The stirring time is not particularly limited as long as the hydration reaction proceeds sufficiently to obtain the desired magnesium hydroxide slurry, and can be, for example, 0.5 to 6 hours.

Step (e) is a step of filtering the magnesium hydroxide slurry of the step (d), washing with water, and drying to obtain magnesium hydroxide particles. Thereby, the magnesium hydroxide particles of the present invention can be obtained.

The magnesium oxide particles of the present invention can be contained in the atmosphere by containing the magnesium hydroxide particles of the present invention or the magnesium hydroxide particles obtained according to the production method comprising the steps (a) to (e) of the present invention. It is obtained by a step of calcination at 500 to 1400 °C.

The calcination of the magnesium hydroxide particles can be carried out by calcination using an electric furnace or the like. Here, the calcination can be achieved by a calcination method comprising the steps of: raising the temperature to a calcination temperature at a predetermined temperature increase rate; and maintaining the calcination temperature for a predetermined period of time. The heating rate is preferably from 1 to 20 ° C / min, preferably from 3 to 10 ° C / min. The calcination temperature is from 500 to 1400 ° C, preferably from 600 to 1300 ° C. The time during which the calcination temperature is maintained, that is, the calcination time, is preferably from 0.1 to 5 hours, preferably from 0.1 to 3 hours. Here, when the calcination temperature is less than 500 ° C, the amount of heat is insufficient and magnesium hydroxide remains. On the other hand, when the calcination temperature is more than 1400 ° C, the magnesium oxide is subjected to grain growth and cannot be a rod-shaped magnesium oxide.

In this manner, rod-shaped magnesium hydroxide particles and magnesium oxide particles having excellent dispersibility can be obtained. The shape of the primary particles of the magnesium hydroxide particles and the magnesium oxide particles obtained by the production method of the present invention is preferably a scaly shape, and is similar to the example of the scaly shape of Fig. 1 . The scaly primary particle of the present invention has a thickness of 0.01 to 0.1 μm, preferably 0.01 to 0.05 μm, and the circumscribed surface of the surface The diameter is in the range of 0.2 to 5 μm, preferably 0.5 to 2.5 μm. Preferably, according to the production method of the present invention, the rod-shaped magnesium hydroxide particles and the magnesium oxide particles obtained by aggregating the scaly primary particles of the present invention can be obtained.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples, but the invention is not limited by the examples.

[Analytical method] (1) Laser diffraction scattering particle size distribution measurement

The cumulative 10% particle diameter (D ₁₀ ) of the volume basis and the cumulative 50% particle diameter (D ₅₀ of the volume basis) were measured using a laser diffraction scattering type particle size distribution measuring apparatus (trade name: MT3300, manufactured by Nikkiso Co., Ltd.). ), and the cumulative 90% particle size (D ₉₀ ) of the volume basis.

(2) Elemental mass measurement

Elements of the object to be measured in the particles (Ag, Al, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hf, In, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Si, Sr, Ti, Tl, V, Zn, and Zr) were measured by dissolving the sample in an acid using an ICP emission spectrometer (trade name: SPS-5100, manufactured by Seiko Instruments).

For the Cl system, a spectrophotometer (trade name: UV-2550, Shimadzu Corporation) was used, and after the sample was dissolved in an acid, the mass was measured.

(3) BET specific surface area measurement method

The specific surface area was measured in accordance with a gas adsorption method using a specific surface area measuring device (trade name: Macsorb 1210, manufactured by MOUNTECH Co., Ltd.).

(4) Ig-loss assay

Using an electric furnace (made by Maru Electric Co., Ltd.), and at 1000 ° C, 3600 seconds The pieces were measured for Ig-loss.

[Example 1]

The acicular magnesium carbonate prepared by reacting a magnesium sulfate solution with sodium carbonate is calcined at a calcination temperature of 1200 ° C to have a 50% particle diameter (D ₅₀ ) of 1.12 μm and a specific surface area of 10.64 m ² / g magnesium oxide was placed in a constant temperature and humidity machine at a temperature of 80 ° C and a humidity of 90% for 3 hours to partially hydrate the surface to obtain a specific surface area of 13.46 m ² /g, and an Ig-loss of 9.08%. magnesium.

By oxidizing acicular magnesium oxide in a part of the reaction, an ion-exchanged aqueous solution containing 0.5% by mass of zinc oxide and 1 liter of ion-exchanged water in terms of a metal element is added in terms of metal element, 0.5. The reaction solution was prepared by mass% of aluminum chloride hexahydrate and 100 g of hydrated acicular magnesium oxide and 0.02 mol of propionic acid. The temperature of the produced reaction liquid was raised to 60 ° C, and 100 g of magnesium oxide obtained by partially hydrating the surface was charged to obtain a mixed liquid. After the magnesium oxide was added, the temperature of the reaction liquid was raised to 95 ° C, and the mixture was adjusted to have a peripheral speed of 9.1 m/s using a stirrer (T.K. uniform disperser manufactured by PRIMIX Co., Ltd.) and allowed to react for 1 hour.

Subsequently, a magnesium hydroxide slurry was produced by stirring at 90 ° C for 4 hours at a rotational speed at which the slurry was sufficiently stirred. The prepared magnesium hydroxide slurry was filtered, washed with water, and dried to obtain a rod-shaped magnesium hydroxide particle of the present invention.

[Embodiment 2]

The procedure was carried out in the same manner as in Example 1 except that aluminum sulfate was used instead of aluminum chloride.

[Example 3]

In addition to the needle-shaped magnesium oxide, it was allowed to stand in a constant temperature and humidity machine at a temperature of 60 ° C and a humidity of 90% for 12 hours to partially hydrate the surface, and the specific surface area was set to 10.18 m ² /g, and the Ig-loss was set to 21.42%. The procedure was carried out in the same manner as in Example 1.

[Example 4]

Magnesium hydroxide prepared in Example 1 was calcined at 600 ° C for 1 hour in an atmosphere to obtain magnesium oxide particles.

[Example 5]

Magnesium hydroxide prepared in Example 1 was calcined at 800 ° C for 1 hour in an atmosphere to obtain magnesium oxide particles.

[Embodiment 6]

Magnesium hydroxide prepared in Example 1 was calcined at 1000 ° C for 1 hour in an atmosphere to obtain magnesium oxide particles.

[Embodiment 7]

The same procedure as in Example 1 was carried out except that propionic acid was changed to acetic acid.

[Embodiment 8]

The same procedure as in Example 1 was carried out except that propionic acid was changed to butyric acid.

[Comparative Example 1]

The same procedure as in Example 1 was carried out except that a 50% particle diameter of 1.19 μm and a specific surface area of 10.82 m ² /g were used instead of needle-shaped magnesium oxide. Further, the Ig-loss of the raw material magnesium oxide was 0.78%.

[Comparative Example 2]

The same procedure as in Example 1 was carried out except that magnesium oxide was used without hydrating a part of the surface.

[Comparative Example 3]

In addition to the needle-shaped magnesium oxide, it was allowed to stand in a constant temperature and humidity machine at a temperature of 80 ° C and a humidity of 90% for 12 hours, and the specific surface area was 8.09 m ² /g, and the Ig-loss was 26.78%. Example 1 was carried out in the same manner.

[Comparative Example 4]

In addition to the needle-shaped magnesium oxide, it was allowed to stand in a constant temperature and humidity machine at a temperature of 60 ° C and a humidity of 90% for 3 hours, and the specific surface area was set to 12.41 m ² /g, and the Ig-loss was set to 11.5%, and the calcination temperature was set. The procedure was carried out in the same manner as in Example 4 except that the temperature was 1500 °C.

The measurement results of the magnesium hydroxide particles and the magnesium oxide particles obtained by the above examples and comparative examples are shown in Table 1.

As is clear from the results of Table 1, the magnesium hydroxide particles and the magnesium oxide particles of the present invention are obtained by agglomerating scaly primary particles, having a 50% particle diameter (D ₅₀ ) of 1.0 to 10.0 μm and a specific surface area of 10 m. ² / g or more. Further, D ₉₀ /D ₁₀ was 10 or less, and it was confirmed that the dispersibility was excellent. On the other hand, as is clear from the results of Table 2, in Comparative Example 1, spherical magnesium hydroxide particles were used. Further, the specific surface area of the magnesium hydroxide particles of Comparative Example 2 was 8.26 m ² /g. Further, the magnesium hydroxide particles of Comparative Example 3 were in an amorphous shape in which aggregates of various shapes were doped, and the specific surface area was 7.45 m ² /g. Further, in the magnesium oxide particles of Comparative Example 4, when the granules were grown and the scaly magnesium hydroxide was changed to magnesium oxide, the shape disappeared and became amorphous, and the specific surface area was 6.87 m ² /g.

(industrial availability)

In the method for producing magnesium hydroxide and magnesium oxide of the present invention, since the specific surface area can be easily controlled by using only the magnesium oxide of the hydration-adjusting raw material such as a constant temperature and humidity machine, magnesium hydroxide and magnesium oxide can be easily produced.

Since the magnesium hydroxide particles and the magnesium oxide particles of the present invention have a rod shape, a 50% particle diameter is small and uniform, and have good dispersibility and a high specific surface area, they are highly useful in various fields. Moreover, since the production method of the present invention can easily prepare the magnesium hydroxide and the magnesium oxide particles as described above, the convenience is high. The magnesium hydroxide particles of the present invention are used as coating agents for inkjet paper, flame retardants, heat storage materials, catalysts, and electronic materials, and can be used as optical materials and inkjets as applications of magnesium oxide particles. Use of paper coating agents, catalysts, and electronic materials.

Claims (8)

A magnesium hydroxide particle obtained by agglomerating scaly primary particles having an aspect ratio (particle length L/particle cross-sectional diameter D) in the range of 1.5 to 20, determined by laser diffraction scattering particle size distribution The volume cumulative 50% particle diameter (D ₅₀ ) is 1.0 to 10.0 μm, and the specific surface area is 10 m ² /g or more. The magnesium hydroxide particles according to the first aspect of the invention, wherein the metal hydroxide element further contains 0.1 to 5.0% by mass of one or more selected from the group consisting of Zn, Zr, Hf, and Ti. The metal element and the metal element are further contained in an amount of 0.1 to 5.0% by mass based on one or more metal elements selected from the group consisting of divalent and trivalent metal elements (however, Zn, Zr, Hf, and Ti systems) except). A magnesium oxide particle obtained by agglomerating scaly primary particles having an aspect ratio (particle length L/particle cross-sectional diameter D) in the range of 1.5 to 20, measured by a laser diffraction scattering particle size distribution The volume cumulative 50% particle diameter (D ₅₀ ) is 1.0 to 10.0 μm, and the specific surface area is 10 m ² /g or more. The magnesium oxide particles according to the third aspect of the invention, wherein the metal oxide element further contains 0.1 to 5.0% by mass of one or more metals selected from the group consisting of Zn, Zr, Hf, and Ti. The element and the metal element further contain 0.1 to 5.0% by mass of one or more metal elements selected from the group consisting of divalent and trivalent metal elements (except for Zn, Zr, Hf, and Ti). ). A method for producing magnesium hydroxide particles, comprising: (a) a dispersion liquid containing one or more compounds selected from the group consisting of compounds of Zn, Zr, Hf, and Ti, and is selected from the group consisting of divalent and trivalent One or more compounds of a group consisting of a chloride of a valence metal element and a nitrate of a divalent or trivalent metal element (except for a compound of Zn, Zr, Hf, and Ti), and further adding an organic acid a step of obtaining a reaction liquid; (b) a reaction liquid of the step (a) and a volume cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction scattering particle size distribution of 0.1 to 10 μm, and a specific surface area a step of mixing 1.0 to 20.0 m ² /g and having an Ig-loss of 2.0 to 25.0% of a partially hydrated acicular magnesium oxide to obtain a mixed solution; here, a group selected from the group consisting of Zn, Zr, Hf, and Ti The compound of one or more kinds is 0.1 to 5.0% by mass based on a part of the hydrated acicular magnesium oxide, and is selected from the group consisting of chlorides of divalent and trivalent metal elements, and divalent and trivalent metal elements. One or more compounds of the group consisting of nitrates, in terms of metal elements, It is 0.1 to 5.0% by mass with respect to a part of the hydrated acicular magnesium oxide; the organic acid is 0.01 to 3.0 mol with respect to 100 g of a part of the hydrated acicular magnesium oxide; (c) the mixture of the step (b) is 50 to 100 a temperature of ° C, a step of mixing using a mixer having a peripheral speed of 7 to 20 m/s; (d) a step of obtaining a magnesium hydroxide slurry by stirring at a temperature of 30 to 100 ° C; and (e) a step (d) The magnesium hydroxide slurry is filtered, washed with water and dried to obtain magnesium hydroxide particles. The manufacturing method according to claim 5, wherein a part of the hydrated acicular magnesium oxide in the step (b) is a volume cumulative 50% particle diameter measured by a laser diffraction scattering particle size distribution (D) ₅₀ ) needle-shaped magnesium oxide particles having a specific surface area of 1.0 to 15.0 m ² /g, which is 0.1 to 10 μm, are placed in a constant temperature and humidity machine at a temperature of 40 to 95 ° C and a humidity of 60 to 95% for 0.5 to 24 hours, thereby obtaining . The production method according to claim 5, wherein a concentration of a portion of the hydrated acicular magnesium oxide in the mixed liquid of the step (b) is 20 to 200 g/L. A method for producing a magnesium oxide particle, the method for producing the magnesium oxide particle, comprising the magnesium hydroxide particle according to claim 1 or 2, or according to any one of claims 5 to 7 of the patent application scope The magnesium hydroxide particles obtained by the production method are calcined at 500 to 1400 ° C in an atmospheric environment.