Magnesium hydroxide manufacturing method and magnesium hydroxide

Abstract

An object of the present disclosure is to provide a method for producing magnesium hydroxide that reduces the need for treating organic matter discharged during the production process. mixing an aqueous solution of a magnesium salt with an aqueous alkali solution to obtain a first mixture containing a precipitate product; mixing the first mixture with an inorganic anion to obtain a second mixture; and and subjecting the second mixed liquid to hydrothermal treatment at 100°C or higher to obtain magnesium hydroxide, A method for producing magnesium hydroxide, wherein the inorganic anion includes an inorganic anion capable of functioning as a monovalent anion in an aqueous solution.

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing magnesium hydroxide and magnesium hydroxide. [Background technology]

[0002] Patent Document 1 describes a method for producing magnesium hydroxide, in which an organic ligand is added to an aqueous solution of a water-soluble salt of a divalent metal including magnesium in an amount of less than 10 mol % relative to the total moles of the divalent metal including magnesium, and the resulting solution is co-precipitated with an alkali in an amount of at least 0.95 equivalents relative to the total equivalents of the divalent metal including magnesium, followed by hydrothermal treatment at 100°C or higher.

[0003] Patent Document 2 describes a method in which an alkali is added to a mixed aqueous solution of a water-soluble magnesium salt and a monovalent organic acid or a salt thereof to cause coprecipitation, or an aqueous solution of an alkali is added to an aqueous solution of a water-soluble magnesium salt to cause coprecipitation, and then a monovalent organic acid or a salt thereof is added, and the resulting slurry is subjected to hydrothermal treatment at 100°C or higher. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-141558 [Patent Document 2] International Publication No. 2012 / 050222 Summary of the Invention [Problem to be solved by the invention]

[0005] In the method described in Patent Document 2, a large amount of organic ligands is present in the wastewater, and a great deal of effort is required for wastewater treatment. Moreover, the method described in Patent Document 1 cannot be said to be able to sufficiently reduce the amount of organic acids and the like in the wastewater.

[0006] On the other hand, methods for producing magnesium hydroxide often use organic substances, but when such methods are carried out, there are restrictions on discharge of wastewater into rivers, so the wastewater must be recovered and reused or subjected to reduction treatment.

[0007] In the above-mentioned recycling method, it is necessary to remove water from wastewater that has been diluted by reaction or washing water, etc., and to concentrate the organic matter, which requires a heating device and a pressure reducing device for removing water, resulting in high equipment and running costs. In addition, when reducing organic matter, methods such as using adsorbents, coagulants, or microorganisms to remove and reduce organic matter from wastewater have been considered, but these methods also have the problem of high treatment process costs.

[0008] An object of the present disclosure is to provide a method for producing magnesium hydroxide that reduces the need for treating organic matter discharged during the production process. [Means for solving the problem]

[0009] A first embodiment of the present disclosure provides a method for producing magnesium hydroxide. The method for producing magnesium hydroxide includes a step of mixing an aqueous solution of a magnesium salt with an aqueous alkaline solution to obtain a first mixture containing a precipitate product. The method for producing magnesium hydroxide includes a step of mixing the first mixed liquid with an inorganic anion to obtain a second mixed liquid. The method for producing magnesium hydroxide includes a step of subjecting the second mixed liquid to hydrothermal treatment at 100° C. or higher to obtain magnesium hydroxide. The inorganic anions include inorganic anions that can function as monovalent anions in an aqueous solution.

[0010] In the second embodiment of the present disclosure, in the first embodiment, the alkaline aqueous solution may contain a basic compound. The content of the basic compound may be 0.95 equivalents or less relative to the content of magnesium contained in the aqueous solution of the magnesium salt.

[0011] In a third embodiment of the present disclosure, in any one of the first and second embodiments, the inorganic anion may include an oxoanion that can function as a monovalent anion in an aqueous solution.

[0012] In the fourth embodiment of the present disclosure, the oxoanion capable of functioning as a monovalent anion in the aqueous solution in the third embodiment may include one or more selected from carbonate ions, bicarbonate ions, molybdate ions, vanadate ions, aluminate ions, nitrate ions, phosphite ions, chlorite ions, hypochlorite ions, and borate ions.

[0013] In a fifth embodiment of the present disclosure, in any one of the first to fourth embodiments, in the second mixed liquid, the amount of the inorganic anion may be 0.05 moles or more and 1.5 moles or less per 100 moles of magnesium.

[0014] In a sixth embodiment of the present disclosure, in any one of the first to fifth embodiments, the inorganic anion is mixed with the second mixed solution as a salt or a compound containing the inorganic anion; Examples of the salt or compound include sodium carbonate, sodium bicarbonate, sodium molybdate, sodium vanadate, potassium aluminate, sodium nitrate, sodium phosphate with or without residue, sodium chlorite, ammonium carbonate, ammonium bicarbonate, sodium hypochlorite, and boric acid, and may contain one or more compounds selected from sodium carbonate, sodium bicarbonate, sodium molybdate, sodium vanadate, potassium aluminate, sodium nitrate, sodium phosphite, sodium chlorite, and boric acid.

[0015] In a seventh embodiment of the present disclosure, in any one of the first to sixth embodiments, the first mixed liquid further contains an organic substance, The organic substance may contain one or more selected from the group consisting of hydroxycarboxylic acids and salts thereof, dicarboxylic acids and salts thereof, amines, amino acids, and polyhydric alcohols.

[0016] In an eighth embodiment of the present disclosure, in the seventh embodiment, the amount of the organic substance in the first mixed liquid can be 0.01 mol or more and 1 mol or less with respect to 100 mol of magnesium.

[0017] In a ninth embodiment of the present disclosure, in any one of the first to eighth embodiments, the magnesium hydroxide may have an average aspect ratio of 20 or more.

[0018] A tenth embodiment of the present disclosure provides magnesium hydroxide comprising an inorganic anion capable of functioning as a monovalent anion in aqueous solution, and having an average aspect ratio of 20 or greater.

[0019] In an eleventh embodiment of the present disclosure, in any one of the tenth embodiments described above, the amount of the inorganic anion may be 0.5% by mass or less relative to 100% of the magnesium hydroxide.

[0020] In a twelfth embodiment of the present disclosure, in any one of the tenth to eleventh embodiments, the inorganic anion may include a carbonate ion.

[0021] In a thirteenth embodiment of the present disclosure, any one of the tenth to twelfth embodiments may further contain an organic substance. The amount of the organic matter may be 0.05% by mass or less relative to the magnesium hydroxide.

[0022] In a fourteenth embodiment of the present disclosure, in any one of the tenth to thirteenth embodiments, the average thickness of the magnesium hydroxide may be less than 60 nm.

[0023] In a fifteenth embodiment of the present disclosure, in any one of the tenth to fourteenth embodiments, the average diameter of the magnesium hydroxide may be 1 μm or more and 3 μm or less.

[0024] In a sixteenth embodiment of the present disclosure, in any one of the tenth to fifteenth embodiments, the tensile elongation measured by the following method may be 100% or more and 1,000% or less. [Method for measuring tensile elongation] A resin composition is prepared by mixing 100 parts by mass of a resin composed of 95 parts by mass of ethylene-vinyl acetate copolymer resin and 5 parts by mass of elastomer with 140 parts by mass of magnesium hydroxide. The resin composition is kneaded using a batch-type twin-screw kneader at 120 to 200°C, a rotation speed of 5 to 100 rpm, and a kneading time of 5 to 60 minutes. The kneaded resin composition is processed by press molding to prepare a 1 mm thick JIS K6251 No. 5 dumbbell test piece. A tensile test is performed on the obtained test piece using a tensile tester in accordance with JIS K7161 at a pulling rate of 200 / min. The elongation at break is measured as the tensile elongation.

[0025] A seventeenth embodiment of the present disclosure provides a resin composition including a resin and any one of the magnesium hydroxides described in the tenth to sixteenth embodiments.

[0026] In an eighteenth embodiment of the present disclosure, in any one of the seventeenth embodiments described in the seventeenth embodiment, the content of the magnesium hydroxide can be 50 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the resin.

[0027] A 19th embodiment of the present disclosure provides a molded article formed from any one of the resin compositions described in the 17th to 18th embodiments.

[0028] A twentieth embodiment of the present disclosure provides a wiring material having a coating layer formed from any one of the resin compositions described in the seventeenth and eighteenth embodiments. [Effects of the Invention]

[0029] According to the manufacturing method of the present disclosure, the need for treating organic matter discharged in the manufacturing process can be reduced. DETAILED DESCRIPTION OF THE INVENTION

[0030] In the present disclosure, "magnesium hydroxide" and other salts or compounds are not limited to magnesium hydroxide (Mg(OH)2) as a compound and other salts or compounds, respectively, and may contain elements such as Ca, Si, Cl, S, Al, and Fe as impurities.

[0031] In the present disclosure, magnesium hydroxide may be magnesium hydroxide particles. In the present disclosure, "particles" refers to an aggregate of particulate materials that are independent of each other. The shape of each particle may be spherical, irregular, or the like. When the particle shape is spherical, "spherical" is not limited to "true spherical."

[0032] The method for producing magnesium hydroxide of the present disclosure includes: mixing an aqueous solution of a magnesium salt with an aqueous alkali solution to obtain a first mixture containing a precipitate product; a step of mixing the first mixture with an inorganic anion capable of functioning as a monovalent anion in an aqueous solution to obtain a second mixture; and and a step of subjecting the second mixed liquid to hydrothermal treatment at 100°C or higher to obtain magnesium hydroxide.

[0033] According to the manufacturing method of the present disclosure, it is possible to produce magnesium hydroxide using a reduced amount of organic material, thereby reducing the need for treatment of organic material discharged during the manufacturing process, preferably significantly reducing the need for such treatment, and in some cases eliminating the need for such treatment. In a preferred embodiment, according to the manufacturing method of the present disclosure, magnesium hydroxide having a high average aspect ratio can be produced while reducing the amount of organic material used. While the present disclosure should not be interpreted as being limited to a particular theory, the reason why the manufacturing method of the present disclosure can achieve such effects is thought to be as follows. That is, in the manufacturing method of the present disclosure, when the precipitated product is subjected to hydrothermal treatment, an inorganic anion capable of functioning as a monovalent anion in an aqueous solution is coexistent. During hydrothermal treatment, the inorganic anion capable of functioning as a monovalent anion in an aqueous solution is thought to specifically adsorb to the c-axis plane, which is the vertical direction of the magnesium hydroxide crystals, and suppress vertical crystal growth, thereby controlling the particle thickness. As a result, it is thought that magnesium hydroxide having a high average aspect ratio can be obtained even when the amount of organic material used is small. Furthermore, magnesium hydroxide having a high average aspect ratio is expected to have high orientation in resin.

[0034] In the manufacturing method of the present disclosure, an aqueous solution of a magnesium salt and an aqueous alkali solution are mixed to obtain a first mixture containing a precipitate product. 2+ ) and hydroxide ions (OH - It is believed that this precipitated product results from the precipitation of magnesium hydroxide (Mg(OH)2).

[0035] The magnesium salt may be one or more selected from magnesium chloride and magnesium nitrate. By using such magnesium salt, magnesium hydroxide crystals can be grown satisfactorily.

[0036] The concentration of the magnesium salt in the aqueous solution of the magnesium salt may be preferably 0.5 mol / L or more and 4.3 mol / L or less, more preferably 1 mol / L or more and 4 mol / L or less, and even more preferably 1.5 mol / L or more and 4 mol / L or less.

[0037] The alkaline aqueous solution means a basic aqueous solution. The alkaline aqueous solution preferably contains a basic compound. Examples of such basic compounds include alkali metal hydroxides, alkaline earth metal hydroxides, and basic compounds such as amines.

[0038] The alkali metal hydroxides include sodium hydroxide and potassium hydroxide, the alkaline earth metal hydroxides include calcium hydroxide, and the amines include ammonia. Among these, alkaline earth metal hydroxides are preferred as the basic compound, and sodium hydroxide is more preferred.

[0039] The content of the basic compound in the alkaline aqueous solution is preferably 0.95 equivalents or less, more preferably 0.7 to 0.95 equivalents, and even more preferably 0.7 to 0.9 equivalents, relative to the content of magnesium in the aqueous magnesium salt solution. When the amount of the basic compound is within this range, precipitation of magnesium hydroxide can be promoted. In the present disclosure, when the content of a certain component is 1 equivalent to the content of another component, it means that the amount of substance of the certain component is equivalent to the amount of substance of the other component. The same applies when the equivalent amount is other than 1 equivalent.

[0040] The first mixed solution may further contain an organic substance. For example, when magnesium hydroxide is produced using only an inorganic substance such as a carbonate, adding a large amount of carbonate can produce magnesium hydroxide with a higher aspect ratio. On the other hand, adding a large amount of carbonate can produce calcium carbonate as a by-product and adhere to the magnesium hydroxide, which may have a negative impact on the flame retardant effect, etc. It is believed that adding an organic substance to the first mixed solution has the effect of reducing the amount of calcium carbonate produced as a by-product.

[0041] The organic substance preferably contains one or more selected from the group consisting of hydroxycarboxylic acids and salts thereof, dicarboxylic acids and salts thereof, amines, amino acids, and polyhydric alcohols.

[0042] Examples of the hydroxycarboxylic acid include lactic acid, glycolic acid, glyceric acid, hydroxybutyric acid, pantoic acid, quinic acid, salicylic acid, vanillic acid, syringic acid, orsellitic acid, gallic acid, mandelic acid, benzilic acid, and malic acid. Examples of the salts of hydroxycarboxylic acids include alkali metal salts such as sodium salts.

[0043] Examples of the dicarboxylic acid include maleic acid, fumaric acid, oxalic acid, malonic acid, succinic acid, itaconic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, and terephthalic acid. Examples of the salts of dicarboxylic acids include alkali metal salts such as sodium salts.

[0044] Examples of the amine include diethanolamine, triethanolamine, ethylenediamine, putrescine, cadaverine, ethambutol, and phenylenediamine.

[0045] Examples of the amino acids include glycine, tryptophan, histidine, glutamic acid, aspartic acid, and proline.

[0046] Examples of the polyhydric alcohol include propylene glycol, ethylene glycol, glycerin, and sorbitol.

[0047] The organic substance preferably contains one or more selected from hydroxycarboxylic acids and their salts, dicarboxylic acids and their salts, and amines, more preferably one or more selected from hydroxycarboxylic acids and their salts, and dicarboxylic acids and their salts, and even more preferably one or more selected from sodium lactate, glycolic acid, sodium succinate, malonic acid, succinic acid, oxalic acid, malic acid, maleic acid, fumaric acid, itaconic acid, and phthalic acid.

[0048] In one embodiment, the amount of the organic substance is preferably 2 mol or less, more preferably 0.01 mol or more and 1 mol or less, and even more preferably 0.05 mol or more and 0.5 mol or less, relative to 100 mol of magnesium contained in the aqueous magnesium salt solution. The production method of the present disclosure allows an inorganic substance to coexist during hydrothermal treatment, and even when the amount of organic substance is small, it is easy to produce sodium hydroxide having a high average aspect ratio.

[0049] In another embodiment, the amount of the organic substance is preferably 2 mol or less, more preferably 0.005 mol or more and 2 mol or less, even more preferably 0.001 mol or more and 2 mol or less, even more preferably 0.01 mol or more and 1 mol or less, and even more preferably 0.05 mol or more and 0.5 mol or less, relative to 100 mol of magnesium contained in the aqueous magnesium salt solution. The production method of the present disclosure allows an inorganic substance to coexist during hydrothermal treatment, and therefore, even when the amount of organic substance is small, it is easy to produce sodium hydroxide having a high average aspect ratio.

[0050] The order in which the magnesium salt aqueous solution, the alkaline aqueous solution, and the organic substance are mixed is not particularly limited. For example, a magnesium salt, an organic substance, and water may be mixed to obtain an aqueous solution of the magnesium salt containing the organic substance, and then the mixture may be mixed with an alkaline aqueous solution. Alternatively, an alkaline aqueous solution containing an organic substance may be mixed with an aqueous solution of the magnesium salt.

[0051] The method for mixing the aqueous solution of the magnesium salt, the aqueous alkali solution, and the organic substance used as needed is not particularly limited, and typically, the mixture can be mixed by stirring.

[0052] The temperature during the mixing is not particularly limited. In one embodiment, the mixing may be carried out preferably at 5° C. or higher and 50° C. or lower, more preferably at 10° C. or higher and 45° C. or lower, and even more preferably at 10° C. or higher and 40° C. or lower. The mixing time may be 1 minute or higher and 10 hours or lower, more preferably at 10 minutes or higher and 8 hours or lower.

[0053] Next, the first mixture containing the precipitated product is mixed with inorganic anions to obtain a second mixture. The inorganic anions include an inorganic anion capable of functioning as a monovalent anion in aqueous solution. By allowing the precipitated product and the inorganic anion capable of functioning as a monovalent anion in aqueous solution to coexist, the inorganic anion capable of functioning as a monovalent anion in aqueous solution can be present in the vicinity of the precipitated product, magnesium hydroxide, which is thought to suppress vertical crystal growth during subsequent hydrothermal treatment. In the present disclosure, "capable of functioning as a monovalent anion" means that the anion exists primarily as a monovalent anion in the aqueous solution within the pH range of the aqueous solution during the reaction. For example, an anion "capable of functioning as a monovalent anion" may be an anion having a pK a1 is lower than the pH of the aqueous solution during this reaction, and pK a2 The pH range of the aqueous solution used in the present reaction may be, for example, preferably 8.0 to 10, more preferably 8.5 to 9.5.

[0054] The inorganic anion preferably includes an oxoanion that can function as a monovalent anion in an aqueous solution. In the present disclosure, an oxoanion refers to an anion formed by the cooperation of a certain element and oxygen. When the inorganic anion includes an oxoanion, it is believed that the inorganic anion can more easily interact with magnesium hydroxide crystals, facilitating the growth of magnesium hydroxide with a high average aspect ratio.

[0055] In this disclosure, oxoanions that can function as monovalent anions in aqueous solution include not only monovalent oxoanions but also oxoanions that can exist as divalent or higher oxyanions and that can combine with protons to form monovalent anions in aqueous solution within the pH range of the aqueous solution used in the present reaction. Examples of oxoanions that can function as monovalent anions include carbonate ions.

[0056] The oxoanions that can function as monovalent anions in the aqueous solution preferably include one or more selected from carbonate ions, bicarbonate ions, molybdate ions, vanadate ions, aluminate ions, nitrate ions, phosphite ions, chlorite ions, hypochlorite ions, and borate ions, more preferably one or more selected from carbonate ions, bicarbonate ions, molybdate ions, vanadate ions, aluminate ions, nitrate ions, phosphite ions, hypochlorite ions, and borate ions, and particularly preferably carbonate ions.

[0057] The proportion of oxoanions that can function as monovalent anions in the aqueous solution may be preferably 80 mol% or more and 100 mol% or less, more preferably 90 mol% or more and 100 mol% or less, and even more preferably 95 mol% or more and 100 mol% or less, of the inorganic anions.

[0058] The inorganic anions may include inorganic anions that can function as divalent or higher anions in an aqueous solution and / or inorganic anions that can function as monovalent anions in an aqueous solution, other than oxoanions.

[0059] In the second mixed liquid, the amount of the inorganic anion may be preferably 2 moles or less, more preferably 0.05 moles or more and 1.5 moles or less, and even more preferably 0.1 moles or more and 1.0 moles or less, relative to 100 moles of magnesium contained in the first mixed liquid.

[0060] In one embodiment, when the first mixed liquid does not contain the organic substance, the amount of the inorganic anion may be preferably 2 moles or less, more preferably 0.1 moles or more and 1.5 moles or less, and even more preferably 0.5 moles or more and 1.0 moles or less, relative to 100 moles of magnesium contained in the first mixed liquid.

[0061] In another aspect, when the first mixed liquid contains the organic substance, the amount of the inorganic anion may be preferably 2 moles or less, more preferably 0.05 moles or more and 1 mole or less, and even more preferably 0.1 moles or more and 0.5 moles or less, relative to 100 moles of magnesium contained in the first mixed liquid.

[0062] The inorganic anion may be mixed with the first liquid mixture as a salt or compound containing the inorganic anion. Examples of such salts containing the inorganic anion include alkali metal salts and ammonium salts of the inorganic anion. Specific examples of salts or compounds containing the inorganic anion include sodium carbonate, sodium bicarbonate, sodium molybdate, sodium vanadate, potassium aluminate, sodium nitrate, sodium phosphite residues, sodium chlorite, ammonium carbonate, ammonium bicarbonate, sodium hypochlorite, and boric acid. The salts or compounds containing the inorganic anion preferably include sodium carbonate, sodium bicarbonate, sodium molybdate, sodium vanadate, potassium aluminate, sodium nitrate, sodium phosphite, sodium chlorite, and boric acid.

[0063] The method for mixing the first mixed solution with the inorganic anion is not particularly limited, and typically, the mixture can be mixed by stirring.

[0064] The temperature during the mixing is not particularly limited. In one embodiment, the mixing may be carried out preferably at 5° C. or higher and 50° C. or lower, more preferably at 10° C. or higher and 45° C. or lower, and even more preferably at 10° C. or higher and 40° C. or lower. The mixing time may be 1 minute or higher and 10 hours or lower, more preferably at 10 minutes or higher and 8 hours or lower.

[0065] Furthermore, the second mixed liquid is subjected to a hydrothermal treatment at 100° C. or higher to obtain magnesium hydroxide, which can grow as crystals.

[0066] The hydrothermal treatment can typically be carried out by holding the second mixed liquid at 100° C. or higher under pressure.

[0067] The pressure (gauge pressure) during the hydrothermal treatment may be preferably 0.1 MPa or more and 4.0 MPa or less, more preferably 0.2 MPa or more and 1.5 MPa or less, and even more preferably 0.4 MPa or more and 1.0 MPa or less.

[0068] The temperature during the hydrothermal treatment may be preferably 100° C. or higher and 250° C. or lower, more preferably 140° C. or higher and 200° C. or lower, and even more preferably 150° C. or higher and 180° C. The higher the hydrothermal treatment temperature, the more likely it is that crystal growth of magnesium hydroxide will be promoted, and the lower the hydrothermal treatment temperature, the easier it will be to reduce costs.

[0069] The hydrothermal treatment time may be preferably 0.5 hours to 8 hours, more preferably 1 hour to 6 hours, and even more preferably 2 hours to 4 hours. The longer the hydrothermal treatment time, the more sustained the crystal growth of magnesium hydroxide can be, and the shorter the hydrothermal treatment time, the easier it is to reduce costs. The mixed liquid after the hydrothermal treatment may be subjected to treatments such as solid-liquid separation, washing, drying, etc., thereby obtaining a dried magnesium hydroxide.

[0070] The method for the solid-liquid separation is not particularly limited and may be, for example, filtration. The filtration may be carried out under normal pressure, elevated pressure, or reduced pressure. The temperature during the filtration may be preferably 5°C or higher and 50°C or lower, more preferably 10°C or higher and 40°C or lower, and even more preferably 10°C or higher and 35°C or lower.

[0071] The washing can be carried out using a washing solvent such as water. In one embodiment, the washing can be carried out by mixing the filtered magnesium hydroxide with the washing solvent and performing solid-liquid separation. The amount of the washing solvent can be preferably 1 part by mass or more and 100 parts by mass or less, more preferably 5 parts by mass or more and 50 parts by mass or less, and even more preferably 10 parts by mass or more and 30 parts by mass or less, per part by mass of the obtained magnesium hydroxide. The solid-liquid separation can be carried out by the same method as the solid-liquid separation of the mixed liquid after the hydrothermal treatment.

[0072] The number of times of washing is not particularly limited, and may be preferably from 1 to 10 times, more preferably from 1 to 5 times, and even more preferably from 1 to 3 times.

[0073] The drying can typically be carried out after solid-liquid separation of the mixed solution or the washed mixture. The drying temperature can be preferably 60°C or higher and 300°C or lower, more preferably 80°C or higher and 200°C or lower, and even more preferably 100°C or higher and 150°C or lower. The drying time can be preferably 1 hour or higher and 100 hours or lower, more preferably 2 hours or higher and 50 hours or lower, and even more preferably 8 hours or higher and 24 hours or lower.

[0074] The dried product may be further pulverized. This pulverization can facilitate control of the particle size of the magnesium hydroxide. The pulverization is typically carried out by dry pulverization.

[0075] The magnesium hydroxide obtained by the above-described production method is also within the technical scope of the present disclosure. Such magnesium hydroxide has a high average aspect ratio and is expected to have good orientation when mixed with a resin.

[0076] The magnesium hydroxide contains an inorganic anion. The inorganic anion has the same meaning as the inorganic anion described above, and preferably contains an oxoanion capable of functioning as a monovalent anion in an aqueous solution, more preferably one or more selected from carbonate ion, bicarbonate ion, molybdate ion, vanadate ion, aluminate ion, nitrate ion, phosphite ion, chlorite ion, hypochlorite ion, and borate ion, still more preferably one or more selected from carbonate ion, bicarbonate ion, molybdate ion, vanadate ion, aluminate ion, nitrate ion, phosphite ion, hypochlorite ion, and borate ion, and particularly preferably carbonate ion.

[0077] The amount of inorganic anion relative to magnesium hydroxide is preferably more than 0% by mass and 0.5% by mass or less, more preferably 0.05% by mass or more and 0.4% by mass or less, and even more preferably 0.1% by mass or more and 0.35% by mass or less. When the amount of inorganic anion is within this range, it is believed that the amount of impurities contained in magnesium hydroxide can be reduced, and the dispersibility in resin and orientation in resin can be improved.

[0078] The amount of inorganic anions, for example carbonate ions, can be measured by the AGK method in accordance with JIS R 9101.

[0079] The magnesium hydroxide preferably contains an organic substance, which has the same meaning as the organic substance described above and preferably contains one or more selected from the group consisting of hydroxycarboxylic acids and their salts, dicarboxylic acids and their salts, amines, amino acids, and polyhydric alcohols, more preferably one or more selected from hydroxycarboxylic acids and their salts, dicarboxylic acids and their salts, and amines, even more preferably one or more selected from hydroxycarboxylic acids and their salts, and dicarboxylic acids and their salts, and particularly preferably one or more selected from sodium lactate, glycolic acid, sodium succinate, malonic acid, succinic acid, oxalic acid, malic acid, maleic acid, fumaric acid, itaconic acid, and phthalic acid.

[0080] The amount of the organic substance is preferably 0% by mass or more and 0.05% by mass or less, more preferably 0.005% by mass or more and 0.045% by mass or less, and even more preferably 0.01% by mass or more and 0.04% by mass or less, relative to the magnesium hydroxide. By keeping the amount of the organic substance within this range, it is thought that the amount of impurities contained in the magnesium hydroxide can be reduced, and the magnesium hydroxide will have good dispersibility in the resin and good orientation in the resin.

[0081] The amount of organic matter can be measured by high performance liquid chromatography.

[0082] In the present disclosure, the average aspect ratio refers to the average value of the aspect ratios of magnesium hydroxide particles. By evaluating the average aspect ratio rather than the aspect ratio of a single magnesium hydroxide particle, it becomes easier to evaluate the properties of the magnesium hydroxide particles as an aggregate.

[0083] The average aspect ratio of magnesium hydroxide may be preferably from 20 to 80, more preferably from 30 to 70, and even more preferably from 40 to 60. When the average aspect ratio of magnesium hydroxide is within this range, it is believed that the dispersibility in the resin and the orientation in the resin will be good.

[0084] The average diameter of the magnesium hydroxide is preferably 0.5 μm to 10 μm, more preferably 0.7 μm to 5 μm, and even more preferably 1 μm to 3 μm. When the average diameter of the magnesium hydroxide is within this range, it is believed that the dispersibility in the resin and the orientation in the resin are good.

[0085] The average thickness of the magnesium hydroxide may be preferably 10 nm or more and 100 nm or less, more preferably 15 nm or more and 80 nm or less, and even more preferably 20 nm or more and 50 nm or less. In another embodiment, the average thickness of the magnesium hydroxide is preferably less than 60 nm, more preferably 10 nm or more and 55 nm or less, and even more preferably 20 nm or more and 50 nm or less. When the average thickness of the magnesium hydroxide is within this range, it is believed that the dispersibility in the resin and the orientation in the resin are good.

[0086] The average aspect ratio, average diameter, and average thickness are those of primary particles, and can be observed using a scanning electron microscope. In a specific embodiment, they can be measured, for example, by the following method. [Method for measuring average aspect ratio, average diameter and average thickness] Magnesium hydroxide is ultrasonically treated in alcohol for 5 minutes. The structure of the magnesium hydroxide primary particles is then observed using a scanning electron microscope (SEM), and the diameter and thickness are measured. The diameter is calculated as the average of the longest and shortest diameters of the magnesium hydroxide primary particles, observed at a magnification of 10,000x. The arithmetic mean value of the diameters measured for 10 or more magnesium hydroxide primary particles is taken as the average diameter. The thickness is measured at a magnification of 100,000x, and the arithmetic mean value of the thicknesses measured for 10 or more magnesium hydroxide primary particles is taken as the average thickness. The average aspect ratio is calculated by dividing the average diameter by the average thickness.

[0087] The magnesium hydroxide of the present disclosure preferably has a tensile elongation of 100% or more and 1,000% or less, as measured by the following method. The tensile elongation is preferably 200% or more and 900% or less, more preferably 300% or more and 800% or less, and even more preferably 400% or more and 700% or less. The magnesium hydroxide of the present disclosure has good orientation, and when blended with a resin, it is expected to have good orientation and achieve both flame retardancy and tensile properties. [Method for measuring tensile elongation] A resin composition is prepared by mixing 100 parts by mass of a resin composed of 95 parts by mass of ethylene-vinyl acetate copolymer resin and 5 parts by mass of elastomer with 140 parts by mass of magnesium hydroxide. The resin composition is kneaded using a batch-type twin-screw kneader at 120 to 200°C, a rotation speed of 5 to 100 rpm, and a kneading time of 5 to 60 minutes. The kneaded resin composition is processed by press molding to prepare a 1 mm thick JIS K6251 No. 5 dumbbell test piece. A tensile test is performed on the obtained test piece using a tensile tester in accordance with JIS K7161 at a pulling rate of 200 / min. The elongation at break is measured as the tensile elongation.

[0088] As the ethylene vinyl acetate copolymer resin, for example, a resin having a melt flow rate of 4 g / 10 min (measured in accordance with JIS K7210 at 190° C. and a load of 2.16 kg) and a tensile breaking strain of 800% (JIS K7161) can be used. As the elastomer, for example, an elastomer having a melt flow rate of 0.7 g / 10 min (measured at 190° C. in accordance with ASTM D1238) and a tensile breaking strain of more than 1,000% (in accordance with ASTM D638) can be used.

[0089] The technical scope of the present disclosure also includes magnesium hydroxide precursors that can be produced as intermediates in the production methods of the present disclosure. Such magnesium hydroxide precursors contain magnesium hydroxide as a main component and the above-mentioned monovalent inorganic anions.

[0090] The monovalent inorganic anion has the same meaning as defined above, and preferably contains one or more oxoanions selected from carbonate ion, bicarbonate ion, molybdate ion, vanadate ion, aluminate ion, nitrate ion, phosphite ion, chlorite ion, hypochlorite ion, and borate ion, and more preferably contains one or more oxoanions selected from carbonate ion, bicarbonate ion, molybdate ion, vanadate ion, aluminate ion, nitrate ion, phosphite ion, hypochlorite ion, and borate ion.

[0091] In the magnesium hydroxide precursor, the monovalent inorganic anion may be contained as a salt or compound containing the monovalent inorganic anion. The salt or compound containing such an inorganic anion has the same meaning as above, and specific examples thereof include sodium carbonate, sodium bicarbonate, sodium molybdate, sodium vanadate, potassium aluminate, sodium nitrate, sodium phosphite residues, sodium chlorite, ammonium carbonate, ammonium bicarbonate, sodium hypochlorite, and boric acid. Preferably, the salt or compound contains sodium carbonate, sodium bicarbonate, sodium molybdate, sodium vanadate, potassium aluminate, sodium nitrate, sodium phosphite, sodium chlorite, and boric acid.

[0092] In the magnesium hydroxide precursor, the content of the monovalent inorganic anion may be preferably 2 moles or less, more preferably 0.05 moles or more and 1.5 moles or less, and even more preferably 0.1 moles or more and 1.0 moles or less, per 100 moles of magnesium contained in the magnesium hydroxide precursor.

[0093] The Mg(OH)2 content in the magnesium hydroxide precursor is preferably 80% by mass or more and 99% by mass or less, more preferably 90% by mass or more and 99% by mass or less, and even more preferably 95% by mass or more and 99% by mass or less.

[0094] The average aspect ratio of the magnesium hydroxide precursor may be preferably from 20 to 80, more preferably from 30 to 70, and even more preferably from 40 to 60. When the average aspect ratio of the magnesium hydroxide precursor is within this range, it is believed that the resulting magnesium hydroxide will have good dispersibility in the resin and good orientation in the resin.

[0095] The average diameter of the magnesium hydroxide precursor is preferably 0.5 μm to 10 μm, more preferably 0.7 μm to 5 μm, and even more preferably 1 μm to 3 μm. When the average diameter of the magnesium hydroxide precursor is within this range, it is believed that the resulting magnesium hydroxide will have good dispersibility in the resin and good orientation in the resin.

[0096] The average thickness of the magnesium hydroxide precursor is preferably 10 nm to 100 nm, more preferably 15 nm to 80 nm, and even more preferably 20 nm to 50 nm. When the average thickness of the magnesium hydroxide precursor is within this range, it is believed that the resulting magnesium hydroxide will have good dispersibility in the resin and good orientation in the resin.

[0097] The magnesium hydroxide can be produced by washing and drying the magnesium hydroxide as needed.

[0098] The magnesium hydroxide can be preferably used as an additive for resins. The magnesium hydroxide obtained by the manufacturing method of the present disclosure uses a reduced amount of organic matter in the manufacturing process and preferably has a high average aspect ratio. Therefore, such magnesium hydroxide is expected to have good orientation when dispersed in a resin, and can be suitably used as an additive for resins, particularly as a flame retardant, reinforcing agent, gas barrier agent, rust inhibitor, rubber bagging inhibitor, neutralizing agent, food additive (anti-caking agent, magnesium reinforcing agent, etc.), antacid, laxative, foam regulator, pigment, anti-slip agent, etc. In a preferred embodiment, it can be suitably used as a flame retardant, reinforcing agent, or gas barrier agent.

[0099] The present disclosure also encompasses within its technical scope a method for producing a resin composition, which includes mixing magnesium hydroxide and a resin to obtain a resin composition, and a resin composition containing magnesium hydroxide and a resin.

[0100] The content of magnesium hydroxide in such a resin composition is preferably 50 parts by mass or more and 200 parts by mass or less, more preferably 60 parts by mass or more and 190 parts by mass or less, and even more preferably 70 parts by mass or more and 180 parts by mass or less, relative to 100 parts by mass of the resin. When the content of magnesium hydroxide is within this range, it is expected that the orientation when dispersed in the resin will be good, and that both flame retardancy and tensile elongation can be achieved.

[0101] Examples of the resin include thermoplastic resins such as polyolefin resins, polyamide resins, and polyphenylene sulfide resins, and thermosetting resins such as epoxy resins, phenolic resins, silicone resins, urea resins, melamine resins, and unsaturated polyesters.

[0102] The magnesium hydroxide and the resin can be mixed as appropriate depending on the type of resin.

[0103] The technical scope of the present disclosure also includes molded articles formed from the resin composition, such as electronic devices, building materials, and automotive parts (electrical and electronic components, electrical components, exterior components, interior components, etc.), various packaging materials, household goods, office supplies, piping, agricultural materials, wiring materials, etc.

[0104] The technical scope of the present disclosure also includes wiring materials having a coating layer formed from the resin composition. The thickness of the coating layer is not limited and can be selected depending on the purpose and application. Examples of the wiring materials include electric wires and cables.

[0105] The present disclosure can provide a production method that reduces the need for treating organic matter discharged during the production process. In a preferred embodiment, the production method of the present disclosure can produce magnesium hydroxide with a high average aspect ratio while reducing the amount of organic matter used. The magnesium hydroxide obtained by the production method of the present disclosure is expected to have good orientation when dispersed in a resin, and can be suitably used as an additive for resins, particularly as a flame retardant, reinforcing agent, gas barrier agent, rust inhibitor, rubber bagging inhibitor, neutralizing agent, food additive (anti-caking agent, magnesium reinforcing agent, etc.), antacid, laxative, foam regulator, pigment, anti-slip agent, etc., and in a preferred embodiment, can be suitably used as a flame retardant, reinforcing agent, or gas barrier agent. [Example]

[0106] The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is not limited thereto.

[0107] Example 1 300 mL of a 2 mol / L aqueous magnesium chloride solution was placed in a 1 L container, and 300 mL of a 3.2 mol / L aqueous sodium hydroxide solution was added under stirring to allow the reaction to proceed. The amount of NaOH contained in the sodium hydroxide solution was equivalent to 0.8 equivalents per mole of magnesium contained in the magnesium chloride solution. 30 mL of a 0.2 mol / L aqueous sodium carbonate solution (equivalent to 1 mol% relative to magnesium) was added to the precipitated product as a salt containing an inorganic anion, and the mixture was transferred to a 1 L autoclave and subjected to hydrothermal treatment at 170°C for 4 hours under stirring. After cooling to below 100°C, the mixture was removed from the autoclave, filtered, washed with water, dried, crushed, and sieved to obtain magnesium hydroxide.

[0108] Example 2 Magnesium hydroxide was obtained in the same manner as in Example 1, except that sodium hydrogen carbonate was used as the salt containing an inorganic anion instead of sodium carbonate.

[0109] Example 3 0.13 g of 50% sodium lactate solution (equivalent to 0.1 mol% relative to magnesium) was added and dissolved in 300 mL of 2 mol / L magnesium chloride solution to obtain a mixed aqueous solution. The mixed aqueous solution was placed in a 1 L container, and 300 mL of 3.2 mol / L sodium hydroxide solution was added under stirring to allow the reaction to proceed. The amount of NaOH contained in the sodium hydroxide solution was equivalent to 0.8 equivalents per mole of magnesium contained in the magnesium chloride solution. 15 mL of 0.2 mol / L sodium carbonate solution (equivalent to 0.5 mol% relative to magnesium) was added to the precipitated product as a salt containing an inorganic anion, transferred to a 1 L autoclave, and hydrothermal treated at 170°C for 4 hours under stirring. After cooling to below 100°C, the mixture was removed from the autoclave, filtered, washed with water, dried, crushed, and sieved to obtain magnesium hydroxide.

[0110] Example 4 Magnesium hydroxide was obtained in the same manner as in Example 3, except that sodium carbonate was used in an amount corresponding to 1 mol % relative to magnesium as the salt containing an inorganic anion.

[0111] Example 5 Magnesium hydroxide was obtained in the same manner as in Example 3, except that sodium succinate in an amount equivalent to 0.1 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 0.1 mol % relative to magnesium.

[0112] Example 6 Magnesium hydroxide was obtained in the same manner as in Example 3, except that sodium lactate was used as the organic substance in an amount equivalent to 2.0 mol % relative to magnesium. The amount of carbonate ions as inorganic anions was measured by the AGK method in accordance with JIS R 9101, and it was confirmed that the amount of carbonate ions contained was 0.14 parts by mass per 100 parts by mass of magnesium hydroxide. Furthermore, the amount of organic matter was measured by high performance liquid chromatography, and it was confirmed that the amount of lactic acid contained was 0.014 parts by mass per 100 parts by mass of magnesium hydroxide.

[0113] Example 7 Magnesium hydroxide was obtained in the same manner as in Example 6, except that, in terms of reaction rate, NaOH equivalent to 0.7 equivalents per mole of magnesium was used instead of NaOH equivalent to 0.8 equivalents per mole of magnesium.

[0114] Example 8 Magnesium hydroxide was obtained in the same manner as in Example 7, except that malonic acid in an amount equivalent to 0.01 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 2.0 mol % relative to magnesium. The amount of carbonate ions as inorganic anions was measured by the AGK method in accordance with JIS R 9101, and it was confirmed that the amount of carbonate ions contained was 0.19 parts by mass per 100 parts by mass of magnesium hydroxide. Furthermore, the amount of organic matter was measured by high performance liquid chromatography, and it was confirmed that the amount of malonic acid contained was 0.013 parts by mass per 100 parts by mass of magnesium hydroxide.

[0115] Example 9 Magnesium hydroxide was obtained in the same manner as in Example 7, except that succinic acid in an amount equivalent to 0.1 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 2.0 mol % relative to magnesium.

[0116] Example 10 Magnesium hydroxide was obtained in the same manner as in Example 7, except that oxalic acid in an amount equivalent to 0.1 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 2.0 mol % relative to magnesium.

[0117] Example 11 Magnesium hydroxide was obtained in the same manner as in Example 7, except that malic acid in an amount equivalent to 0.01 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 2.0 mol % relative to magnesium. The amount of carbonate ions as inorganic anions was measured by the AGK method in accordance with JIS R 9101, and it was confirmed that the magnesium hydroxide contained 0.24 parts by mass of carbonate ions per 100 parts by mass of magnesium hydroxide.

[0118] Example 12 Magnesium hydroxide was obtained in the same manner as in Example 7, except that maleic acid in an amount equivalent to 0.01 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 2.0 mol % relative to magnesium. The amount of carbonate ions as inorganic anions was measured by the AGK method in accordance with JIS R 9101, and it was confirmed that the amount of carbonate ions contained was 0.33 parts by mass per 100 parts by mass of magnesium hydroxide.

[0119] Example 13 Magnesium hydroxide was obtained in the same manner as in Example 7, except that fumaric acid in an amount equivalent to 0.01 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 2.0 mol % relative to magnesium.

[0120] Example 14 Magnesium hydroxide was obtained in the same manner as in Example 7, except that itaconic acid in an amount equivalent to 0.1 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 2.0 mol % relative to magnesium.

[0121] Example 15 Magnesium hydroxide was obtained in the same manner as in Example 7, except that phthalic acid in an amount equivalent to 0.01 mol % relative to magnesium was used as the organic substance instead of sodium lactate in an amount equivalent to 2.0 mol % relative to magnesium.

[0122] Example 16 A mixed aqueous solution was obtained by adding and dissolving 3.63 kg of a 50% by mass sodium lactate aqueous solution (equivalent to 2 mol% relative to magnesium) as an organic substance to 450 L of a 1.8 mol / L magnesium chloride aqueous solution. The mixed aqueous solution was placed in a 1,000 L autoclave, and 95 L of a 12 mol / L sodium hydroxide aqueous solution was added under stirring to allow the reaction to proceed. The amount of NaOH contained in the sodium hydroxide aqueous solution was equivalent to 0.7 equivalents per mole of magnesium contained in the magnesium chloride aqueous solution. To this precipitated product, 2.5 L of a 1.3 mol / L sodium carbonate aqueous solution (equivalent to 0.4 mol% relative to magnesium) was added as a salt containing an inorganic anion, and the mixture was subjected to hydrothermal treatment at 175°C for 4 hours under stirring. After cooling to below 100°C, the mixture was removed from the autoclave, filtered, washed with water, and dispersed in deionized water to produce a slurry.

[0123] Example 17 A mixed aqueous solution was obtained by adding and dissolving 1.13 kg of a 0.5% by mass malonic acid solution (equivalent to 0.0075 mol% relative to magnesium) as an organic substance to 450 L of a 1.6 mol / L magnesium chloride aqueous solution. The mixed aqueous solution was placed in a 1,000 L autoclave, and 90 L of a 10.8 mol / L sodium hydroxide aqueous solution was added under stirring to allow the reaction to proceed. The amount of NaOH contained in the sodium hydroxide aqueous solution was equivalent to 0.8 equivalents per mole of magnesium contained in the magnesium chloride aqueous solution. 2.8 L of a 1.3 mol / L sodium carbonate aqueous solution (equivalent to 0.5 mol% relative to magnesium) was added to the precipitated product as a salt containing an inorganic anion, and the mixture was subjected to hydrothermal treatment at 170°C for 4 hours under stirring. After cooling to below 100°C, the mixture was removed from the autoclave, filtered, washed with water, and dispersed in deionized water to produce a slurry containing magnesium hydroxide.

[0124] Comparative Example 1 300 mL of a 2 mol / L magnesium chloride aqueous solution was placed in a 1 L container, and 300 mL of a 3.2 mol / L sodium hydroxide aqueous solution was added under stirring to allow for reaction. The amount of NaOH contained in the sodium hydroxide aqueous solution was equivalent to 0.8 equivalents per mole of magnesium contained in the magnesium chloride aqueous solution. This precipitated product was transferred to a 1 L autoclave and subjected to hydrothermal treatment at 170°C for 4 hours under stirring. After cooling to below 100°C, the product was removed from the autoclave, filtered, washed with water, dried, crushed, and sieved to obtain the magnesium hydroxide of the comparative example.

[0125] Comparative Example 2 A mixed aqueous solution was obtained by adding and dissolving 0.13 g of 50% sodium lactate (0.1 mol % relative to magnesium) in 300 mL of a 2 mol / L magnesium chloride aqueous solution. The mixed aqueous solution was placed in a 1 L container, and 300 mL of a 3.2 mol / L sodium hydroxide aqueous solution was added under stirring to allow the reaction to proceed. The amount of NaOH contained in the sodium hydroxide aqueous solution was equivalent to 0.8 equivalents per mole of magnesium contained in the magnesium chloride aqueous solution. The precipitated product was transferred to a 1 L autoclave and subjected to hydrothermal treatment at 170°C for 4 hours under stirring. After cooling to below 100°C, the product was removed from the autoclave, filtered, washed with water, dried, crushed, and sieved to obtain the magnesium hydroxide of the comparative example.

[0126] Comparative Example 3 Magnesium hydroxide of the comparative example was obtained in the same manner as in Comparative Example 2, except that 2 mol % sodium lactate relative to magnesium was used instead of 0.1 mol % sodium lactate relative to magnesium.

[0127] Comparative Example 4 Magnesium hydroxide of Comparative Example was obtained in the same manner as Comparative Example 2, except that 0.1 mol % of sodium succinate relative to magnesium was used instead of 0.1 mol % of sodium lactate relative to magnesium.

[0128] Comparative Example 5 Magnesium hydroxide of the comparative example was obtained in the same manner as in Example 1, except that sodium metasilicate (Na2SiO3) in an amount equivalent to 1 mol % relative to magnesium was used as the salt containing an inorganic anion instead of sodium carbonate in an amount equivalent to 1 mol % relative to magnesium. In addition, metasilicate ions function as divalent anions in an aqueous solution.

[0129] Comparative Example 6 KISUMA (registered trademark) 5A (magnesium hydroxide manufactured by Kyowa Chemical Industry Co., Ltd.) was used. The amount of carbonate ions as inorganic anions was measured by the AGK method in accordance with JIS R 9101, and it was confirmed that the magnesium hydroxide contained 0.2 parts by mass of carbonate ions per 100 parts by mass of magnesium hydroxide.

[0130] Comparative Example 7 Magnesium hydroxide of Comparative Example was obtained in the same manner as in Comparative Example 2, except that 50 mol % sodium acetate relative to magnesium was used instead of 0.1 mol % sodium lactate relative to magnesium.

[0131] [Method for measuring average aspect ratio, average diameter and average thickness] The magnesium hydroxide obtained in the examples and comparative examples was subjected to ultrasonic treatment in an alcohol solvent for 5 minutes. Thereafter, the structure of the magnesium hydroxide primary particles was observed using a scanning electron microscope (JEOL Ltd., JSM-7600F), and the diameter and thickness were measured. The diameter was observed at a magnification of 10,000 times, and calculated as the average of the longest and shortest diameters of the magnesium hydroxide primary particles. The arithmetic mean value of the diameters measured for 10 or more magnesium hydroxide primary particles was used as the average diameter. The thickness was observed at a magnification of 100,000 times, and the thickness was measured for 10 or more magnesium hydroxide primary particles, and the arithmetic mean value was used as the average thickness. The average aspect ratio was calculated by dividing the average diameter by the average thickness.

[0132] [Table 1]

[0133] The magnesium hydroxides of Examples 16 and 17 and Comparative Examples 6 and 7 were used to carry out the following tests.

[0134] The magnesium hydroxides of Examples 16 and 17 and Comparative Example 7 were surface-treated before the tests were conducted. Sodium stearate was used as a surface treatment agent, in an amount of 1.5% by mass relative to the magnesium hydroxide, and dissolved in deionized water heated to 80°C to prepare a sodium stearate-containing treatment liquid. Similarly, the sodium stearate-containing treatment liquid was added to a magnesium hydroxide slurry heated to 80°C, and the mixture was stirred and maintained at 80°C for 30 minutes. The surface-treated slurry was cooled, filtered, and washed with water. The cake was then dried to obtain stearic acid-treated magnesium hydroxide.

[0135] [Method of producing resin composition] A resin composition was produced by adding 130 to 160 parts by mass of (stearic acid-treated) magnesium hydroxide to a resin consisting of 95 parts by mass of ethylene vinyl acetate copolymer resin (EVA resin, Evaflex V421, manufactured by Mitsui Dow Polychemicals) and 5 parts by mass of elastomer (Tafmer MH7020, manufactured by Mitsui Chemicals). The resin and (stearic acid-treated) magnesium hydroxide were kneaded using a batch-type twin-screw kneader (Plastograph EC, manufactured by Brabender). For Comparative Examples 6 and 7, the kneading was carried out at 120 to 160°C, a rotation speed of 15 to 80 rpm, and a kneading time of 15 minutes. For Examples 16 and 17, the (stearic acid-treated) magnesium hydroxide was kneaded at 120 to 200°C, a rotation speed of 5 to 80 rpm, and a kneading time of 30 minutes.

[0136] Evaflex V421 (manufactured by Mitsui Dow Polychemicals) had a melt flow rate of 4 g / 10 min (measured in accordance with JIS K7210 at 190°C and a load of 2.16 kg) and a tensile breaking strain of 800% (in accordance with JIS K7161-1 and JIS K7161-2). TAFMER MH7020 (Mitsui Chemicals) had a melt flow rate of 0.7 g / 10 min (measured at 190°C in accordance with ASTM D1238) and a tensile breaking strain of over 1,000% (in accordance with ASTM D638).

[0137] [UL94V test] The obtained resin composition was processed by press molding (ANSF-50HH / C, manufactured by Shindo Metal Industries Co., Ltd.) to prepare a test piece of 127 mm x 13 mm x 3 mm thick. The resulting test specimens were subjected to a flame retardancy test in accordance with the UL-94 50W vertical flame test method using a combustion tester (252-UL-94, manufactured by Yasuda Seiki Seisakusho Co., Ltd.), and the minimum amount of magnesium hydroxide required to satisfy the V-0 standard was determined. The results are shown in Table 2. The test was conducted once for a set of five test specimens.

[0138] [Tensile test] The resin composition obtained by adding the minimum amount of magnesium hydroxide required to satisfy the V-0 standard in the UL94 test to 100 parts by mass of resin was processed by press molding (ANSF-50HH / C, manufactured by Shindo Metal Industries Co., Ltd.) to prepare No. 5 dumbbell test pieces with a thickness of 1 mm. The tensile elongation of the obtained test pieces was measured using a tensile tester (Universal Material Testing Machine Model 5967, manufactured by Instron Corporation) at a tension speed of 200 mm / min in accordance with JIS K7161. The results are shown in Table 2. The test was carried out seven times.

[0139] [Water resistance test] The resin composition obtained by adding the minimum amount of magnesium hydroxide required to satisfy the V-0 standard in the UL94 test to 100 parts by mass of resin was processed by press molding (ANSF-50HH / C, manufactured by Shindo Metal Industries Co., Ltd.) to prepare test pieces measuring 100 mm x 100 mm x 1 mm thick. The obtained test pieces were immersed in warm water at 70°C for 168 hours. The volume resistivity (VR) of the test pieces before and after immersion was measured using a resistance meter (5451, manufactured by ADC) at an applied voltage of 500V. The weights of the test pieces before and after immersion were also measured, and the weight increase rate was determined. These results are shown in Table 2. The test was performed three times.

[0140] [Melt flow rate (MFR) measurement] The resin composition was prepared by adding the minimum amount of magnesium hydroxide necessary to satisfy the V-0 standard in the UL9V test to 100 parts by mass of resin, and the melt flow rate (MFR) of the resulting composition was measured using a melt indexer (TM21-F2A, manufactured by Tateyama Scientific Co., Ltd.). According to JIS K7210, the sample was extruded at 190°C under a load of 21.6 kg, and the extrusion rate (g / 10 min) was measured. The results are shown in Table 2. The measurement was performed three times.

[0141] [Table 2]

[0142] [Flame retardant] In the UL94 standard vertical flame test, materials are ranked in order of flammability, V-2 > V-1 > V-0, based on burning time and whether or not they ignite due to dripping. In this study, the amount of magnesium hydroxide added was varied and the minimum amount of magnesium hydroxide needed to meet the V-0 standard was measured. The smaller this value, the less magnesium hydroxide needed to achieve V-0 flame retardancy, which can be said to be an improvement in flame retardancy. Examples 16 and 17 achieved V-0 with a smaller amount of additive than Comparative Example 6 (KISUMA (registered trademark) 5A), and it can be said that the flame retardancy can be improved.

[0143] [Tensile elongation] Generally, resin compositions containing metal hydroxides such as magnesium hydroxide have the drawback of reduced mechanical properties such as tensile strength and tensile elongation. If the tensile elongation percentage is reduced, the flexibility, which is important for wire coating materials and the like in which magnesium hydroxide is used as a flame retardant, is lost. In particular, the sample of Comparative Example 7 showed a significant decrease in elongation, making it difficult to use as a flame retardant for wire coating materials. On the other hand, the magnesium hydroxides of Examples 16 and 17 showed a larger elongation than Comparative Example 7, and the magnesium hydroxide of Example 16 showed a value close to that of Comparative Example 6 (KISUMA (registered trademark) 5A), demonstrating the ability to maintain tensile elongation while maintaining high flame retardancy, a property not found in conventional high aspect ratio magnesium hydroxide materials.

[0144] [Water resistance test] Volume Resistivity (VR) This is a value that indicates the electrical resistivity of a resin, and indicates how difficult it is for an electric current to pass through the resin. The higher this value, the better the insulating properties. For resin compositions that require insulating properties, such as for wire coatings, materials that can maintain a high value before and after water resistance tests are preferred. Resin compositions with low water resistance tend to absorb water when immersed in warm water, resulting in a decrease in VR. The results show that the VR values ​​of all materials after the test remained the same as before the test, meaning that there are no problems with water resistance.

[0145] Weight gain rate This shows the rate of change in the weight of the test piece before and after the water resistance test, with the result that the higher the water resistance, the lower the weight increase rate. The values ​​for Comparative Example 7 and Examples 16 and 17, which are high aspect ratio materials, are low, indicating that they have better water resistance than Comparative Example 6 (KISUMA (registered trademark) 5A).

[0146] Melt Flow Rate (MFR) This is an evaluation of the fluidity of a thermoplastic resin, and affects its processability and moldability. Higher values ​​are not necessarily better, and there are desirable values ​​depending on various factors such as molding conditions and applications. However, if the MFR value is too low, processability and other factors may deteriorate, which can reduce productivity, so a low MFR is often undesirable. In Comparative Example 7, the MFR value is significantly lower than that of Comparative Example 6 (KISUMA (registered trademark) 5A), and it can be said that the processability is deteriorated. On the other hand, from the results of Examples 16 and 17, although the value is reduced, the degree of reduction is small, and it can be said that the effect on the processability can be reduced. [Industrial Applicability]

[0147] The present disclosure can provide a production method that reduces the need for treating organic matter discharged during the production process. In a preferred embodiment, the production method of the present disclosure can produce magnesium hydroxide with a high average aspect ratio while reducing the amount of organic matter used. The magnesium hydroxide obtained by the production method of the present disclosure is expected to have good orientation when dispersed in a resin, and can be suitably used as an additive for resins, particularly as a flame retardant, reinforcing agent, gas barrier agent, rust inhibitor, rubber bagging inhibitor, neutralizing agent, food additive (anti-caking agent, magnesium reinforcing agent, etc.), antacid, laxative, foam regulator, pigment, anti-slip agent, etc., and in a preferred embodiment, can be suitably used as a flame retardant, reinforcing agent, or gas barrier agent.

Claims

1. mixing an aqueous solution of a magnesium salt with an aqueous alkali solution to obtain a first mixture containing a precipitate product; mixing the first mixture with an inorganic anion to obtain a second mixture; and and subjecting the second mixed liquid to hydrothermal treatment at 100°C or higher to obtain magnesium hydroxide, A method for producing magnesium hydroxide, wherein the inorganic anion contains an inorganic anion capable of functioning as a monovalent anion in an aqueous solution having a pH of 8.0 or more and 10 or less.

2. The alkaline aqueous solution contains a basic compound, 2. The method according to claim 1, wherein the content of the basic compound is 0.95 equivalents or less relative to the content of magnesium contained in the aqueous solution of magnesium salt.

3. The method according to claim 1 , wherein the inorganic anion comprises an oxoanion that can function as a monovalent anion in an aqueous solution having a pH of 8.0 or more and 10 or less.

4. 4. The method according to claim 3, wherein the oxoanion capable of functioning as a monovalent anion in the aqueous solution having a pH of 8.0 or more and 10 or less includes one or more oxoanions selected from carbonate ions, bicarbonate ions, molybdate ions, vanadate ions, aluminate ions, nitrate ions, phosphite ions, chlorite ions, hypochlorite ions, and borate ions.

5. 2. The method according to claim 1, wherein the amount of the inorganic anion in the second mixture is 0.05 mol or more and 1.5 mol or less per 100 mol of magnesium.

6. the inorganic anion is mixed with the second mixture as a salt or a compound containing the inorganic anion; The salt or compound may be sodium carbonate, sodium bicarbonate, sodium molybdate, sodium vanadate, potassium aluminate, sodium nitrate, with or without phosphite residues, sodium chlorite, ammonium carbonate, ammonium bicarbonate, sodium hypochlorite, or boric acid, and the method according to claim 1 further comprises one or more selected from sodium carbonate, sodium bicarbonate, sodium molybdate, sodium vanadate, potassium aluminate, sodium nitrate, sodium phosphite, sodium chlorite, and boric acid.

7. the first mixture further contains an organic substance; The method according to claim 1, wherein the organic substance comprises one or more selected from the group consisting of hydroxycarboxylic acids and salts thereof, dicarboxylic acids and salts thereof, amines, amino acids, and polyhydric alcohols.

8. 8. The method according to claim 7, wherein the amount of the organic substance in the first mixture is 0.001 mol or more and 2 mol or less per 100 mol of magnesium.

9. The method according to claim 1, wherein the magnesium hydroxide has an average aspect ratio of 20 or more.

10. Magnesium hydroxide containing an inorganic anion capable of functioning as a monovalent anion in an aqueous solution having a pH of 8.0 or more and 10 or less, and having an average aspect ratio of 20 or more.

11. 11. The magnesium hydroxide according to claim 10, wherein the amount of the inorganic anion is 0.5% by mass or less relative to the magnesium hydroxide.

12. 11. The magnesium hydroxide of claim 10, wherein the inorganic anion comprises a carbonate ion.

13. The magnesium hydroxide according to claim 10, further comprising an organic substance, the amount of the organic substance being 0.05 mass% or less relative to the magnesium hydroxide.

14. 11. The magnesium hydroxide of claim 10, wherein the average thickness of the magnesium hydroxide is less than 60 nm.

15. The magnesium hydroxide according to claim 10, wherein the average diameter of the magnesium hydroxide is 1 μm or more and 3 μm or less.

16. The magnesium hydroxide according to claim 10, wherein the tensile elongation measured by the following method is 100% or more and 1,000% or less. [Method for measuring tensile elongation] A resin composition is prepared by mixing 100 parts by mass of a resin composed of 95 parts by mass of an ethylene vinyl acetate copolymer resin and 5 parts by mass of an elastomer, and 140 parts by mass of magnesium hydroxide. The resin composition is kneaded using a batch type twin-screw kneader under conditions of 120 to 200° C., a rotation speed of 5 to 100 rpm, and a kneading time of 5 to 60 minutes. The kneaded resin composition is processed by press molding to prepare a 1 mm thick JIS K6251 No. 5 dumbbell test piece. The obtained test piece is subjected to a tensile test using a tensile tester at a tension rate of 200 / min in accordance with JIS K 7161. The elongation at break is measured as the tensile elongation.

17. A resin composition comprising a resin and the magnesium hydroxide according to any one of claims 10 to 16.

18. The resin composition according to claim 17, wherein the content of the magnesium hydroxide is 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin.

19. A molded article formed from the resin composition according to claim 17.

20. A wiring material having a coating layer formed from the resin composition according to claim 17.

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