Magnesium oxide powder for tablet and production method of the same

Abstract

To provide a production method for magnesium oxide powder for tablets that has suppressed bulk density and excellent compression moldability during tableting.SOLUTION: The method includes the steps of (1) preparing a slurry containing magnesium hydroxide and magnesium carbonate, (2) drying the slurry of (1), and (3) calcining the dried product of (2). The ratio of magnesium hydroxide to the total amount of magnesium hydroxide and magnesium carbonate in the slurry of the step (1) is 5 to 70% in mass ratio based on magnesium oxide.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to magnesium oxide powder for tablets and a method for producing the same.

Background Art

[0002] Tablets containing magnesium oxide as a main component and an active ingredient are widely used for various purposes such as antacids, laxatives, magnesium supplementation, and anti-hypomagnesemia. Such tablets are produced by blending additives such as binders and disintegrants with magnesium oxide powder and then tableting.

[0003] Conventionally, as a method for producing magnesium oxide powder, a method of burning and oxidizing metallic magnesium or a method of firing and thermally decomposing magnesium salts has been used. Examples of magnesium salts used as raw materials include magnesium hydroxide and magnesium carbonate (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One of the problems of the present invention is to provide magnesium oxide powder for tablets with a suppressed bulk density and excellent compression moldability during tableting, and a method for producing the same.

Means for Solving the Problems

[0006] As a result of intensive studies, the present inventors have found that by preparing a mixed slurry containing magnesium hydroxide and magnesium carbonate in a predetermined ratio, drying the slurry, and then firing it, magnesium oxide powder for tablets with a suppressed bulk density and excellent compression moldability during tableting can be obtained, and thus completed the present invention.

[0007] That is, the gist of the present invention relates to, for example, the following. [1] A manufacturing method for producing magnesium oxide powder for tablets. The manufacturing method includes an adjustment step, a generation step, and a firing step. The adjustment step prepares a slurry containing magnesium hydroxide and magnesium carbonate. The generation step generates a dried product obtained by drying the slurry. The firing step fires the dried product. In the manufacturing method, the ratio of magnesium hydroxide to the total amount of magnesium hydroxide and magnesium carbonate in the slurry is 5 to 75% in terms of the mass ratio converted to magnesium oxide. [2] In the manufacturing method according to [1], the magnesium hydroxide in the slurry is magnesium hydroxide produced by the seawater method or the bittern method. [3] In the manufacturing method according to [1] or [2], the slurry is prepared by separately preparing a first slurry and a second slurry. The first slurry contains the magnesium hydroxide. The second slurry contains the magnesium carbonate. The slurry is prepared by mixing and stirring the first slurry and the second slurry. [4] In the manufacturing method according to any one of [1] to [3], the firing step is performed at a temperature of 600 to 1000°C. [5] Magnesium oxide powder for tablets. The magnesium oxide powder for tablets is produced by the manufacturing method according to any one of [1] to [4]. [6] The magnesium oxide powder for tablets according to [5] has a BET specific surface area of 39 m 2 / g or less. [7] The magnesium oxide powder for tablets according to [5] or [6] has a bulk density of 85 mL / 10 g or less. [8] Magnesium oxide powder for tablets. The magnesium oxide powder for tablets contains hexagonal columnar magnesium oxide and acicular magnesium oxide. The magnesium oxide powder for tablets has a BET specific surface area of 39 m 2 / g or less. The magnesium oxide powder for tablets has a bulk density of 85 mL / 10 g or less. [9] It is a magnesium oxide tablet. The magnesium oxide tablet contains the magnesium oxide powder for tablets according to any one of [5] to [8].

[10] In the magnesium oxide tablet according to [9], the hardness is 30 N or more.

[11] In the magnesium oxide tablet according to [9] or

[10] , the tensile strength is 1.3 N / mm 2 or more. [Advantages of the Invention]

[0008] According to the present invention, there are provided a magnesium oxide powder for tablets with a suppressed bulk density and excellent compression moldability during tableting, and a method for producing the same. [Brief Description of the Drawings]

[0009]

Figure 1

Figure 2

[0010] Hereinafter, the present invention will be described in detail according to specific embodiments. However, the present invention is not limited to the following embodiments, and can be implemented in any form without departing from the spirit of the present invention.

[0011] One embodiment of the present invention relates to a method for producing magnesium oxide powder for tablets. The production method of this embodiment is characterized by including the following steps. (1) A step of preparing a slurry containing magnesium hydroxide and magnesium carbonate. (2) A step of drying the slurry. (3) A step of firing the dried product.

[0012] In step (1), a slurry containing magnesium hydroxide and magnesium carbonate is prepared. Such a slurry is formed by dispersing magnesium hydroxide and magnesium carbonate in water or an aqueous medium.

[0013] The method for producing magnesium hydroxide used in step (1) is not particularly limited. According to one embodiment, examples include the seawater method or the bittern method. Magnesium hydroxide produced by the seawater method or the bittern method has large particles and is an aggregate, so it has excellent handleability.

[0014] When producing magnesium hydroxide (Mg(OH) 2 ) by the seawater method, the procedure is not limited, but for example, the following can be mentioned. As the magnesium raw material, seawater is used. As the alkali raw material, for example, lime milk is used. These magnesium raw material and alkali raw material are continuously reacted. The reaction temperature is allowed to be natural, and the residence time is, for example, 10 minutes or more. The product obtained by the reaction is concentrated, for example, to a solid content concentration of 5 mass% or more. The obtained concentrated product is washed to remove salts such as sodium, whereby a slurry of magnesium hydroxide can be obtained. Hereinafter, the magnesium hydroxide thus produced is also referred to as "seawater method magnesium hydroxide".

[0015] When producing magnesium hydroxide (Mg(OH) 2 ) by the bittern method, the procedure is not limited, but for example, the following can be mentioned. As the magnesium raw material, bittern is used. As the alkali raw material, for example, lime milk is used. These magnesium raw material and alkali raw material are continuously reacted. The reaction temperature is allowed to be natural, and the residence time is, for example, 10 minutes or more. The obtained product is washed to remove salts such as sodium, whereby a magnesium hydroxide slurry can be obtained. Hereinafter, the magnesium hydroxide thus produced is also referred to as "bittern method magnesium hydroxide".

[0016] As for magnesium hydroxide, one type of magnesium hydroxide may be used alone, or two or more types of magnesium hydroxide may be used in combination at any ratio. The two or more types of magnesium hydroxide may be a combination of magnesium hydroxide obtained by the seawater method and magnesium hydroxide obtained by the bittern method. Alternatively, the two or more types of magnesium hydroxide may be a combination of two or more types of magnesium hydroxide obtained by the seawater method with different BET specific surface areas. Alternatively, the two or more types of magnesium hydroxide may be a combination of two or more types of magnesium hydroxide obtained by the bittern method with different BET specific surface areas.

[0017] Magnesium hydroxide obtained by the seawater method is fine particles and tends to become a powder suitable for tablet use when converted into magnesium oxide. However, since the amount of magnesium in seawater is small, the scale of the manufacturing equipment may become large. Conversely, magnesium hydroxide obtained by the bittern method tends to be magnesium hydroxide with particles grown to a certain extent, but the manufacturing equipment may be relatively compact in some cases.

[0018] The method for producing magnesium carbonate used in step (1) is not particularly limited, and examples include a method of reacting magnesium hydroxide with carbon dioxide gas. The procedure is not limited, but for example, the following procedure can be mentioned. Contact magnesium hydroxide with carbon dioxide gas and react until the pH reaches 7 to 9. Then, heat the reaction product to 80 °C or higher and hold for 30 minutes or more. Magnesium carbonate can be obtained by cooling the reaction product. Magnesium carbonate may be not only one type of magnesium carbonate but also two or more types of magnesium carbonate with different BET specific surface areas. Magnesium carbonate may be natural magnesium carbonate or synthetic magnesium carbonate. Synthetic magnesium carbonate is more preferable because it is easier to control the impurity concentration. Magnesium carbonate specified in the Japanese Pharmacopoeia, heavy magnesium carbonate, is more preferable. In the case of light magnesium carbonate, the bulk density becomes very high, and it tends to be difficult to use for tablet applications.

[0019] The concentrations of magnesium hydroxide and magnesium carbonate in the slurry of step (1) are not particularly limited. According to one aspect, the total concentration of magnesium hydroxide and magnesium carbonate in the slurry can be, for example, 5% by mass or more, or 10% by mass or more, and can also be, for example, 50% by mass or less, or 40% by mass or less, or 30% by mass or less.

[0020] The slurry of step (1) preferably has a characteristic that magnesium hydroxide and magnesium carbonate are in a predetermined ratio. Specifically, the ratio of magnesium hydroxide to the total amount of magnesium hydroxide and magnesium carbonate is preferably usually 5% by mass or more, particularly 10% by mass or more, or 15% by mass or more in terms of the mass ratio in terms of magnesium oxide conversion, and is preferably usually 75% by mass or less, particularly usually 70% by mass or less, and more preferably 65% by mass or less. By setting the ratio of magnesium hydroxide to be not less than the lower limit, the compression moldability during tableting of the obtained magnesium oxide powder can be improved, and the hardness and / or tensile strength of the obtained tablets can be increased. On the other hand, by setting the ratio of magnesium hydroxide to be not more than the upper limit, the bulk density of the obtained magnesium oxide powder can be reduced, and the production efficiency of tablets can be improved.

[0021] The mass of magnesium hydroxide and magnesium carbonate in terms of magnesium oxide conversion can be calculated from the molecular mass of magnesium hydroxide (Mg(OH) 2 )(about 58.320 g / mol), the molecular mass of magnesium carbonate (MgCO 3 )(about 84.3139 g / mol), and the molecular mass of magnesium oxide (MgO)(about 40.3044 g / mol). For example, the mass of 100 g of magnesium hydroxide in terms of magnesium oxide conversion is 100 g×(40.3044 / 58.320)=about 69.11 g, and the mass of 100 g of magnesium carbonate in terms of magnesium oxide conversion is 100 g×(40.3044 / 84.3139)=about 47.80 g.

[0022] The slurry of step (1) may contain water or an aqueous medium, magnesium hydroxide, magnesium carbonate, and one or more other components in addition. Examples of the other components include, but are not limited to, other magnesium salts other than magnesium hydroxide and magnesium carbonate. Examples of the other magnesium salts include, but are not limited to, magnesium chloride, magnesium nitrate, and magnesium sulfate. However, from the viewpoint of increasing the purity of the resulting magnesium oxide and making its physical properties and characteristics uniform, it is preferable that the other components be as few as possible.

[0023] The method for preparing the slurry in step (1) is not particularly limited. According to one aspect, such a slurry can be obtained by dispersing magnesium hydroxide and magnesium carbonate in water or an aqueous medium to form a slurry. According to another aspect, a first slurry obtained by dispersing magnesium hydroxide in water or an aqueous medium to form a slurry and a second slurry obtained by dispersing magnesium carbonate in water or an aqueous medium to form a slurry are prepared, and then these first and second slurries are mixed to obtain such a slurry.

[0024] During the preparation of the slurry in step (1), stirring may be applied. The method of stirring is not particularly limited, and examples include stirring by a rotary blade. The stirring speed is not particularly limited, and for example, it can be set to 5 to 1000 rpm. The stirring time is not particularly limited, and for example, it can be 10 minutes or more, or 20 minutes or more, or 30 minutes or more.

[0025] In step (2), the slurry of (1) is dried. The drying method is not limited. Examples include natural drying, heat drying, ventilation drying, vacuum drying, and combinations thereof, and any of them may be used.

[0026] Before or simultaneously with the drying in step (2), a dehydration treatment may be applied. The dehydration method is not limited. Examples include squeezing treatment, water absorption treatment, volatilization treatment, and combinations thereof.

[0027] The drying time of step (2) is not particularly limited and varies depending on the drying method, the presence or absence of dehydration, and the method thereof. For example, it may be carried out until the moisture in the slurry (moisture of the dried product) is usually 10% by mass or less, and particularly 3% by mass or less.

[0028] In step (3), the dried product of (2) is fired. The firing conditions are not particularly limited, but for example, they can be as follows.

[0029] The firing temperature in step (3) is not restricted, but for example, it can be 500 °C or higher, or 600 °C or higher, or 700 °C or higher, and also, for example, 1300 °C or lower, or 1200 °C or lower, or 1100 °C or lower.

[0030] The firing time in step (3) is not restricted, but for example, it can be 30 minutes or longer, or 60 minutes or longer, or 90 minutes or longer, and also, for example, within 5 hours, or within 3 hours, or within 2 hours.

[0031] Note that the firing temperature and firing time in step (3) can be appropriately adjusted so that the BET specific surface area or other physical properties and characteristics of the finally obtained magnesium oxide satisfy the ranges described below.

[0032] By the manufacturing method of the embodiment described above, it is possible to obtain magnesium oxide powder for tablets with a reduced bulk density and excellent compression moldability during tableting. Although the reason is not clear, it is presumed that magnesium oxide derived from magnesium hydroxide contributes to the reduction of the bulk density, while magnesium oxide derived from magnesium carbonate contributes to the improvement of the compression moldability during tableting. In addition, by drying and firing magnesium hydroxide and magnesium carbonate in a state where they are uniformly slurried, it is presumed that suitable characteristics of both magnesium oxide derived from magnesium hydroxide and magnesium oxide derived from magnesium carbonate are exhibited in a well-balanced manner, and magnesium oxide powder having both characteristics can be obtained. In this specification, being excellent in the "compression moldability" during tableting means that tablets excellent in hardness and / or tensile strength can be obtained when tableted.

[0033] One embodiment of the present invention relates to magnesium oxide powder for tablets manufactured by the manufacturing method of the embodiment. Such magnesium oxide powder has a reduced bulk density and excellent compression moldability during tableting, and can be suitably used for the manufacture of tablets.

[0034] One embodiment of the present invention relates to magnesium oxide powder for tablets that satisfies the following characteristics. Such magnesium oxide powder for tablets can be manufactured, for example, by the manufacturing method of the embodiment, but is not limited thereto.

[0035] The magnesium oxide powder of the present embodiment contains hexagonal columnar magnesium oxide and acicular magnesium oxide when observed with a scanning electron microscope (SEM). According to one aspect, the hexagonal columnar magnesium oxide is derived from magnesium hydroxide, and the acicular magnesium oxide is derived from magnesium carbonate. Without being bound by theory, it is presumed that in the hexagonal columnar magnesium oxide derived from magnesium hydroxide in the magnesium oxide powder of the present embodiment, the appropriate presence of acicular magnesium oxide derived from magnesium carbonate makes it possible to suppress the bulk density and improve the hardness and tensile strength of the tablets during tableting.

[0036] The BET specific surface area of the magnesium oxide powder of this embodiment is not limited, but its upper limit value is, for example, 39 m 2 / g or less, or 38 m 2 / g or less, or 37 m 2 / g or less, which is preferable. By setting the BET specific surface area of the magnesium oxide powder to be below the upper limit, the bulk density of the magnesium oxide powder can be suppressed, and the manufacturing ability during tablet production is likely to be improved. On the other hand, although not limited, its lower limit value is, for example, 15 m 2 / g or more, or 20 m 2 / g or more, or 25 m 2 / g or more. The measurement method of the BET specific surface area of the magnesium oxide powder is not particularly limited. As an example, it can be measured by the gas adsorption method using a specific surface area measuring device.

[0037] The bulk density of the magnesium oxide powder of this embodiment is not limited, but its upper limit value is preferably, for example, 85 mL / 10 g or less, or 80 mL / 10 g or less, or 70 mL / 10 g or less. By setting the bulk density of the magnesium oxide powder to be below the upper limit, the manufacturing ability during tablet production using the magnesium oxide powder is likely to be improved. On the other hand, although not limited, its lower limit value can be, for example, 20 mL / 10 g or more, or 25 mL / 10 g or more, or 30 mL / 10 g or more. The measurement method of the bulk density of the magnesium oxide powder is not particularly limited, but it can be obtained, for example, by measuring the volume and mass of the magnesium oxide powder and calculating the volume per 10 g.

[0038] One embodiment of the present invention relates to a tablet containing magnesium oxide powder. According to one aspect, such a magnesium oxide tablet contains the magnesium oxide powder for tablets of the above-described embodiment as a main component.

[0039] The magnesium oxide tablets of the present embodiment preferably have a hardness and / or a tensile strength equal to or higher than a predetermined value. Specifically, although not limited, the lower limit of the hardness of the magnesium oxide tablets of the present embodiment is preferably, for example, 30 N or higher, or 35 N or higher, or 40 N or higher. On the other hand, although not limited, the upper limit of the hardness is, for example, 98 N or lower. Further, although not limited, the lower limit of the tensile strength of the magnesium oxide tablets of the present embodiment is, for example, 1.3 N / mm 2 or higher, or 1.5 N / mm 2 or higher, or 1.7 N / mm 2 or higher. On the other hand, although not limited, the upper limit of the tensile strength is, for example, 5.0 N / mm 2 or lower. The method for measuring the hardness and tensile strength of the magnesium oxide tablets is not particularly limited, but can be determined, for example, by the method described in the examples below.

[0040] The content of the magnesium oxide powder for tablets contained in the magnesium oxide tablets of the present embodiment is not limited, but as an upper limit, it can be, for example, 100% by mass or less, or 95% by mass or less, or 90% by mass or less with respect to the entire tablet. On the other hand, although not limited, as a lower limit, it can be, for example, 70% by mass or higher, or 80% by mass or higher, or 85% by mass or higher with respect to the entire tablet.

[0041] The magnesium oxide tablets of the present embodiment may contain additives, if necessary. The additives are not limited, but include various pharmaceutically acceptable pharmaceutical additives. Specific examples include excipients, binders, disintegrants, lubricants, pigments, and flavoring agents. Any one of these components may be used alone, or two or more of them may be used in combination in any combination.

[0042] One embodiment of the present invention relates to a method for manufacturing magnesium oxide tablets. According to one aspect, such a manufacturing method includes a tableting step of tableting a raw material containing magnesium oxide powder. According to one aspect, the raw material containing such magnesium oxide powder contains, as a main component, the magnesium oxide powder for tablets of the above-described embodiment. The content rate of the magnesium oxide powder contained in the raw material is not particularly limited, and any content rate can be adopted.

[0043] In the tableting step, the raw material is tableted by any method. For example, tableting can be performed by using a tableting machine. The tableting pressure is also not limited. For example, as the punch pressure per tablet, the upper limit can be 20 kN or less, or 18 kN or less, or 16 kN or less. For example, the lower limit can be 2 kN or more, or 3 kN or more, or 4 kN or more. The shape of the punch is also not limited. For example, the shapes include standard R, two-stage R, sugar-coated R, corner R, corner plane, and rounded corner plane.

[0044] According to one aspect, the manufacturing method of the present embodiment includes a mixing step of mixing a raw material containing magnesium oxide powder before the tableting step. In the mixing step, the raw material containing magnesium oxide powder is mixed by any method.

[0045] The present embodiment relates to a fine granule containing magnesium oxide powder. In one aspect, the fine granule contains, as a main component, magnesium oxide powder. The content rate of the magnesium oxide powder contained in the magnesium oxide fine granule is not particularly limited, and any content rate can be adopted, similar to the case of the magnesium oxide tablet.

[0046] The upper limit of the average particle diameter of the magnesium oxide powder is not restricted, but for example, it can preferably be 850 μm or less, or 700 μm or less, or 500 μm or less. The lower limit of the particle diameter is not restricted, but for example, it can preferably be 100 μm or more, or 200 μm or more, or 300 μm or more.

[0047] One embodiment of the present invention relates to a method for producing magnesium oxide fine granules. According to one aspect, such a production method includes a granulation step of granulating a raw material containing magnesium oxide powder. In one aspect, the raw material containing magnesium oxide powder contains, as a main component, the magnesium oxide powder for tablets of the above-described embodiment. The content rate of the magnesium oxide powder contained in the raw material is not particularly limited as described above, and any content rate can be adopted.

[0048] The granulation step can be carried out, for example, by a fluidized bed granulation method or a dry granulation method to granulate the raw material containing magnesium oxide powder. Among them, the fluidized bed granulation method is preferable from the viewpoint that it is easy to adjust so as to have a desired average particle diameter and bulk density. By the granulation step, magnesium oxide fine granules having a desired average particle diameter as described above can be obtained.

[0049] As described above, various aspects of the present invention have been described, but the present invention is not limited to these aspects. As will be apparent to those skilled in the art, it is also possible to extract any other aspect of the present invention from the above detailed description and the descriptions of the examples and the like described later.

Examples

[0050] Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are merely examples shown for convenience of explanation and the present invention is not limited to these examples in any sense.

[0051] [1. Preparation of Specimen] · Material: As magnesium hydroxide (Mg(OH) 2 ), magnesium hydroxide produced by the seawater method (hereinafter appropriately abbreviated as "seawater method magnesium hydroxide") and magnesium hydroxide produced by the bittern method (hereinafter appropriately abbreviated as "bittern method magnesium hydroxide") were used.

[0052] Magnesium hydroxide produced by the seawater method was generated through the following procedure. Seawater was used as the magnesium raw material. Slaked lime was used as the alkali raw material. The reaction temperature was allowed to be natural, and the magnesium raw material and the alkali raw material were continuously reacted for a residence time of 10 minutes or more. The resulting product was concentrated until the solid content concentration reached 5% by mass or more. The obtained concentrated product was washed to remove salts such as sodium, thereby generating a slurry of magnesium hydroxide produced by the seawater method with a concentration of 10 - 30% by mass (hereinafter abbreviated as "seawater method magnesium hydroxide slurry" as appropriate).

[0053] Magnesium hydroxide produced by the bittern method was generated through the following procedure. Bittern was used as the magnesium raw material. Slaked lime was used as the alkali raw material. The reaction temperature was allowed to be natural, and the magnesium raw material and the alkali raw material were continuously reacted for a residence time of 10 minutes or more. The obtained product was washed to remove salts such as sodium, thereby generating a slurry of magnesium hydroxide produced by the bittern method with a concentration of 10 - 30% by mass (hereinafter abbreviated as "bittern method magnesium hydroxide slurry" as appropriate).

[0054] Magnesium carbonate (MgCO 3 ) was manufactured by the gas absorption method. Specifically, magnesium hydroxide was contacted with carbon dioxide gas and reacted until the pH reached 7 - 9. Then, the product was heated to 80°C or higher and held for 30 minutes or more. Thereafter, the product was cooled to prepare a slurry of magnesium carbonate with a concentration of 5 - 10% by mass (hereinafter abbreviated as "magnesium carbonate slurry" as appropriate).

[0055] · Example 1: The above seawater method magnesium hydroxide slurry and the above magnesium carbonate slurry were mixed at a mass ratio in terms of magnesium oxide conversion of 8 to 2 and stirred for 30 minutes. The obtained mixed slurry was dehydrated using a filter press manufactured by Ishigaki Co., Ltd. at a squeezing pressure of 0.5 MPa or more, and then dried using a hot air dryer. The obtained dried product was calcined using a rotary kiln manufactured by Iwasa Kikai Kogyo Co., Ltd. at a supply rate of 400 kg / hour and a calcination temperature of 600°C or higher, and the specific surface area (BET) of the calcined product was 20 - 60 m 2It was fired until it was in the range of / g. The firing time was about 30 to 120 hours. The obtained fired product was pulverized using an impact pulverizer to obtain a specimen of the magnesium oxide powder of Example 1.

[0056] · Example 2: In Example 1, a specimen of the magnesium oxide powder of Example 2 was obtained by performing the same operations as in Example 1, except that the mixing ratio of the seawater-process magnesium hydroxide slurry and the magnesium carbonate slurry was changed to 5:5 in terms of the mass ratio in terms of magnesium oxide.

[0057] · Comparative Example 1: In Example 1, a specimen of the magnesium oxide powder of Comparative Example 1 was obtained by performing the same operations as in Example 1, except that the seawater-process magnesium hydroxide slurry was used alone instead of the mixed slurry of the seawater-process magnesium hydroxide slurry and the magnesium carbonate slurry.

[0058] · Comparative Example 2: In Example 1, a specimen of the magnesium oxide powder of Comparative Example 2 was obtained by performing the same operations as in Example 1, except that the mixing ratio of the seawater-process magnesium hydroxide slurry and the magnesium carbonate slurry was changed to 2:8 in terms of the mass ratio in terms of magnesium oxide.

[0059] · Example 3: In Example 1, a specimen of the magnesium oxide powder of Example 3 was obtained by performing the same operations as in Example 1, except that a bittern-process magnesium hydroxide slurry was used instead of the seawater-process magnesium hydroxide slurry and the mixture was made in a mass ratio of 8:2 in terms of magnesium oxide with the magnesium carbonate slurry.

[0060] · Example 4: In Example 3, a specimen of magnesium oxide powder of Example 4 was obtained by performing the same operations as in Example 3, except that the mixing ratio of the bitter juice method magnesium hydroxide slurry and the magnesium carbonate slurry was changed to 5:5 in terms of the mass ratio in terms of magnesium oxide conversion.

[0061] · Comparative Example 3: In Example 3, a specimen of magnesium oxide powder of Comparative Example 3 was obtained by performing the same operations as in Example 3, except that the bitter juice method magnesium hydroxide slurry was used alone instead of the mixed slurry of the bitter juice method magnesium hydroxide slurry and the magnesium carbonate slurry.

[0062] · Comparative Example 4: In Example 3, a specimen of magnesium oxide powder of Comparative Example 4 was obtained by performing the same operations as in Example 3, except that the mixing ratio of the bitter juice method magnesium hydroxide slurry and the magnesium carbonate slurry was changed to 2:8 in terms of the mass ratio in terms of magnesium oxide conversion.

[0063] · Comparative Example 5: In Example 1, a specimen of magnesium oxide powder of Comparative Example 5 was obtained by performing the same operations as in Example 1, except that the magnesium carbonate slurry was used alone instead of the mixed slurry of the seawater method magnesium hydroxide slurry and the magnesium carbonate slurry.

[0064] [2. Measurement and Evaluation of Physical Properties and Characteristics] The physical properties and characteristics of each magnesium oxide powder specimen were measured and evaluated by the following procedure.

[0065] · BET Specific Surface Area: For each magnesium oxide powder specimen, the BET specific surface area was measured by the gas adsorption method using a specific surface area measuring instrument (Belsorp MR6 manufactured by Microtrac BEL).

[0066] · Bulk Density: For each magnesium oxide powder sample, the volume and mass were measured, and the volume per 10 g of the powder (mL / 10 g) was determined as the bulk density.

[0067] · Adhesiveness (Discharge Rate): 5.0 g of each magnesium oxide sample after firing was placed in a wide-mouth bottle (manufactured by Yamamura Glass Co., Ltd., material glass, diameter 3.3 cm, bottle height 8 cm), the lid was closed, and it was shaken 100 times. The lid of the bottle was opened and inverted, and the magnesium oxide sample not adhering to the side of the bottle was discharged and its mass was measured. The ratio (discharge rate) of the obtained discharge amount to the initial amount (5.0 g) was determined and used as an index of the adhesiveness of each magnesium oxide sample. The closer the discharge rate is to 100%, the lower the proportion of the magnesium oxide sample adhering to the side of the bottle and the lower the adhesiveness, and it can be said that the powder has improved handling properties.

[0068] · Tablet Thickness, Hardness, and Tensile Strength For each magnesium oxide powder sample, tablets were prepared using a manual tableting machine (HANDTAB-200 manufactured by Ichihashi Seiki Co., Ltd.) under the conditions of a sample amount of 250 mg, a flat punch of 10 mm Φ, and a tableting pressure of 10 kN. The thickness of the obtained tablets was measured. Also, using a tablet hardness tester (Tablet Tester 6D manufactured by Dr. SCHLEUNIGER), the hardness of the tablets was measured, and the tensile strength was determined based on the following formula. Tensile strength (N / mm 2 ) = Hardness / Cross-sectional area (diameter × thickness)

[0069] [3. Results] The preparation conditions of each magnesium oxide powder sample are shown in Table 1 below. Also, the physical properties and characteristics of each magnesium oxide powder sample, and the measurement and evaluation results of the physical properties and characteristics of the tablets obtained by tableting each magnesium oxide powder sample are shown in Table 2 below. Note that the powder of Comparative Example 5 had too high a bulk density and could not be tableted.

[0070]

Table 1

[0071]

Table 2

[0072] From the above results, it can be seen that the magnesium oxide powders of Comparative Examples 1 and 3 obtained by calcining magnesium hydroxide without using magnesium carbonate have insufficient hardness or tensile strength of the tablets during tableting. On the other hand, it can be seen that the magnesium oxide powders of Comparative Examples 2 and 4 obtained by calcining using a small amount of magnesium hydroxide and using magnesium carbonate as the main raw material have a high bulk density and poor tablet manufacturing efficiency. In particular, the magnesium oxide powder of Comparative Example 5 obtained by calcining only magnesium hydroxide without using magnesium carbonate has too high a bulk density and cannot be tableted.

[0073] In contrast, the magnesium oxide powders of Examples 1 to 4 obtained by calcining a material in which magnesium hydroxide and magnesium carbonate are mixed at a predetermined ratio can have the bulk density appropriately suppressed, and also have excellent hardness and tensile strength of the tablets during tableting, and it can be seen that they well balance the characteristics required for magnesium oxide powder for tablets.

[0074] Further, cross-sections of the tablets obtained by tableting each magnesium oxide powder specimen of Example 3 and Comparative Example 4 were observed and imaged with a scanning electron microscope (SEM). The SEM photograph of the tablet using the magnesium oxide powder specimen of Example 3 is shown in Fig. 1, and the SEM photograph of the tablet using the magnesium oxide powder specimen of Comparative Example 4 is shown in Fig. 2. As is clear from this SEM photograph, the magnesium oxide powder of Example 3 moderately contains acicular magnesium oxide indicated by the surrounding line in the photograph within hexagonal columnar magnesium oxide. It is considered that the hexagonal columnar magnesium oxide is derived from magnesium hydroxide, and the acicular magnesium oxide is derived from magnesium carbonate. Although not bound by theory, it is presumed that the appropriate presence of acicular magnesium oxide derived from magnesium carbonate within the hexagonal columnar magnesium oxide derived from magnesium hydroxide makes it possible to improve the hardness and tensile strength of the tablet during tableting while suppressing the bulk density. On the other hand, it is presumed that the proportion of acicular magnesium oxide derived from magnesium carbonate in the magnesium oxide powder of Comparative Example 4 is very large, which is the cause of the increase in bulk density.

Industrial Applicability

[0075] The present invention can be widely applied to magnesium oxide powder for tablets, and its utility value is extremely large.

Claims

1. A manufacturing method for producing magnesium oxide powder for tablets, comprising: (1) An adjustment step of preparing a slurry containing magnesium hydroxide and magnesium carbonate; (2) A production step of producing a dried product by drying the slurry; (3) A firing step of firing the dried product; wherein the ratio of magnesium hydroxide to the total amount of magnesium hydroxide and magnesium carbonate in the slurry is 5 to 75% by mass in terms of magnesium oxide.

2. The manufacturing method according to Claim 1, wherein the magnesium hydroxide in the slurry is magnesium hydroxide produced by the seawater method or the bittern method.

3. The manufacturing method according to Claim 1, wherein the slurry is prepared by separately preparing a first slurry containing magnesium hydroxide and a second slurry containing magnesium carbonate, and mixing and stirring the first slurry and the second slurry.

4. The manufacturing method according to Claim 1, wherein the firing step is performed at a temperature of 600 to 1000°C.

5. Magnesium oxide powder for tablets produced by the manufacturing method according to any one of Claims 1 to 4.

6. The BET specific surface area is 39 m ２ / g or less, the magnesium oxide powder for tablets according to claim 5.

7. The magnesium oxide powder for tablets according to Claim 5, having a bulk density of 85 mL / 10 g or less.

8. Magnesium oxide powder for tablets, which contains hexagonal columnar magnesium oxide and acicular magnesium oxide, has a BET specific surface area of 39 m ２ / g or less and a bulk density of 85 mL / 10 g or less.

9. A magnesium oxide tablet containing the magnesium oxide powder for tablets according to Claim 8.

10. The magnesium oxide tablet according to Claim 9, having a hardness of 30 N or more.

11. The tensile strength is 1.3 N / mm ２ or more, the magnesium oxide tablet according to claim 9.

Images