Metal iodide tablet manufacturing method

Abstract

To provide a method for manufacturing a metal iodide tablet in which contamination of a black substance is suppressed.SOLUTION: A metal iodide tablet manufacturing method includes a process in which metal iodide powders are compression-molded by use of a tableting machine. The tableting machine comprises an upper pestle, a mortar and a lower pestle in this order, and has a cap, which prevents the metal iodide powders from falling into the mortar, on the upper pestle.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing metal iodide tablets. [Background technology]

[0002] Various studies have been conducted on metal iodide tablets.

[0003] Patent Document 1 describes a method for producing tablet-type metal iodide, in which metal iodide powder is compression-molded at 10 to 50°C to have a crushing strength of 4 kgf or more and a particle size of 5 to 20 mm, and describes that it is possible to provide a method for producing metal iodide that is sufficiently prevented from caking even when stored for a long period of time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-137824 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a method for producing metal iodide tablets with reduced contamination with black substances. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems, and have found that the inclusion of black substances in tablets can be suppressed by providing a tablet press for compressing metal iodide tablets with an upper punch, a mortar, and a lower punch in this order, and providing the upper punch with a cap for preventing the powder of metal iodide from falling into the mortar, thereby completing the present invention. According to the present invention, there is provided a method for producing metal iodide tablets as follows.

[0007] [1] 1. A method for producing a metal iodide tablet, comprising: The method includes a step of compressing and molding a powder of a metal iodide using a tablet press, A method for producing metal iodide tablets, wherein the tablet press is equipped with an upper punch, a mortar, and a lower punch in that order, and the upper punch has a cap for preventing the metal iodide powder from falling into the inside of the mortar. [2] The method for producing a metal iodide tablet according to [1], wherein, in the compression molding, a pressure of 0.3 kN or more and less than 1.0 kN is applied to the powder of the metal iodide. [3] The method for producing metal iodide tablets described in [1] or [2], wherein the tablet press is equipped with an upper punch, a mortar and a lower punch made of metal, and one or more surfaces selected from the group consisting of the upper punch, the mortar and the lower punch are nitrided. [4] The method further includes a step of drying the powder and a step of feeding the powder into the tablet press before the step of compressing, The method for producing metal iodide tablets according to any one of [1] to [3], wherein the moisture content of the powdery material, measured by Karl Fischer coulometric titration according to the following <Moisture content>, between the step of drying the powdery material and the step of feeding the powdery material into the tablet press, is 500 ppm or less relative to the total mass of the powdery material. <Moisture content> 2 g of the powder is placed in a moisture vaporizer and heated at 345°C. The amount of moisture generated is measured by coulometric titration in accordance with JIS K 0113:2005 using a Karl Fischer moisture meter and Karl Fischer reagent, and the moisture content (ppm) is calculated using the following formula (3). Equation (3): Moisture content (ppm) = measured moisture content (mg) / mass of the powder (kg) [5] The method for producing metal iodide tablets described in [4], wherein in the step of drying the powder, the powder is dried at a temperature of 100°C or higher and 180°C or lower. Effect of the Invention

[0008] According to the present invention, a method for producing metal iodide tablets in which the inclusion of black substances is suppressed can be provided. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram showing an example of an upper punch (with cap), a die, and a lower punch of the tablet press of the present embodiment. [Diagram 2] 1 is a diagram showing an example of an upper punch and a cap of a tablet press of this embodiment before the cap is installed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present invention will be described based on the embodiment. In this embodiment, "A to B" indicating a numerical range means A or more and B or less unless otherwise specified. In addition, when a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily.

[0011] <Method of manufacturing metal iodide tablets> The manufacturing method for metal iodide tablets of this embodiment includes a step of compressing and molding a powder of metal iodide using a tablet press. The tablet press is equipped with an upper punch, a mortar and a lower punch in that order, and the upper punch has a cap to prevent the powder of metal iodide from falling into the inside of the mortar.

[0012] The structure of the tablet press will be specifically described with reference to Figs. 1 and 2. The tablet press used in the manufacturing method of metal iodide tablets of this embodiment includes an upper punch 101, a mortar 102, and a lower punch 103 (FIG. 1). With the lower punch 103 inserted into the mortar 102 from below, the mortar 102 is filled with powdered metal iodide, and then the upper punch 101 enters the mortar 102 from above and applies pressure to the powdered metal iodide, thereby compressing and molding the metal iodide tablets.

[0013] In the manufacturing method of metal iodide tablets of this embodiment, the upper punch 101 of the tablet press is provided with a cap 104. Specifically, it is preferable to provide the cap 104 on the lower part of the upper punch 101 (FIG. 1). The cap 104 is made of, for example, rubber, is removable, and can be fitted into a groove on the lower part of the upper punch 101 (FIG. 2). When the cap 104 is attached to the upper punch 101, for example, it has a shape that spreads out toward the upper side (the side opposite to the mortar 102), and as described later, it is possible to prevent the powder of metal iodide adhering to the surface of the upper punch 101 from falling into the inside of the mortar 102.

[0014] The falling of the powder of the metal iodide will be further explained. In one cycle of manufacturing the metal iodide tablet, as described above, the powder of the metal iodide is supplied into the mortar 102 while the lower punch 103 enters the mortar 102 from below, the upper punch 101 enters the mortar 102 from above, and the upper punch 101 and the lower punch 103 compress the powder from above and below to form the metal iodide tablet, and the lower punch 103 pushes up the inside of the mortar 102, and the formed metal iodide tablet is discharged from the inside of the mortar 102 to the outside and collected. When this one cycle is completed, the powder of the metal iodide is supplied again into the mortar 102, and the next tableting cycle is performed. During the repetition of this cycle, the residue of the powder of the metal iodide that has not been formed into a tablet adheres to the surfaces of the upper punch 101 and the lower punch 103 that move up and down. Furthermore, the powder residue attached to the upper punch 101 may fall from the surface of the upper punch 101 into the mortar 102 due to the up-and-down movement of the upper punch 101 and the lower punch 103. The powder residue of the metal iodide attached to the upper punch 101 may be heated by frictional heat generated by metal friction between the upper punch 101 and an upper holder hole (not shown) in which the upper punch 101 is placed, and the burnt and black-colored substance (hereinafter also referred to as black substance) may fall into the mortar 102. In addition, oil may be applied to the surface of the upper punch 101 to reduce friction as described later, and a mixture of oil and the powder of the metal iodide or a mixture of oil and the above-mentioned black substance may fall into the mortar 102. These substances that have fallen into the mortar 102 may be tableted as they are and become foreign matter in the metal iodide tablets. At this time, if the upper punch 101 is provided with a cap 104, the powder residue that has fallen from the surface of the upper punch 101 and the mixture of the powder and oil or black substances described above will fall onto the top surface of the cap 104, thereby preventing the powder residue and the mixture of the powder and oil or black substances from falling into the inside of the mortar 102.

[0015] The tablet press used in the manufacturing method of the metal iodide tablet of this embodiment preferably includes a metal mortar and a pestle. That is, the upper punch 101, the mortar 102, and the lower punch 103 are preferably made of metal. The metal constituting the tablet press preferably includes one or more selected from the group consisting of iron, steel, and brass, and more preferably includes die steel (SKD11). Two or more of these metals may be combined to form an alloy. Since the upper punch 101, the mortar 102, and the lower punch 103 of the tablet press are made of metal, the metal iodide tablets can be manufactured without breakage even when continuously operated at a certain degree of tableting pressure.

[0016] One or more surfaces selected from the group consisting of the metallic upper punch 101, mortar 102, and lower punch 103 are preferably nitrided. By nitriding one or more surfaces selected from the group consisting of the upper punch 101, mortar 102, and lower punch 103, the rust resistance of the tablet press is improved, the inclusion of rust and other impurities in the tablets can be further suppressed, wear of the tablet press can be further suppressed, the inclusion of black substances in the tablets can be further suppressed, and productivity can be further improved. Specific examples of the nitriding treatment of one or more surfaces selected from the group consisting of the upper punch 101, the mortar 102 and the lower punch 103 include a chemical treatment in which the surfaces are heated in a molten salt such as titanium nitride, chromium nitride, potassium nitride and potassium cyanide, a treatment in which the surfaces are heated in a gas atmosphere, and a treatment in which the surfaces are heated in a gas plasma.

[0017] In the metal tablet press used in the above-mentioned method for producing metal iodide tablets, the diameter of the resulting tablet is determined by the sizes of the upper punch 101, the mortar 102, and the lower punch 103. More specifically, the inner diameter of the mortar 102 and the diameters of the upper punch 101 and the lower punch 103 are almost the same as the diameter of the tablet. In addition, in order to set the strength and moldability of the tablet in an appropriate range, the height of the tablet is also determined within a certain range from the diameter of the tablet. Therefore, first, the diameter and approximate height of the target tablet are determined, and then the upper punch 101, the mortar 102, and the lower punch 103 are manufactured in a size that can produce a tablet of that diameter.

[0018] In the above-mentioned compression molding step, pressure is applied to the powder of the metal iodide at a tableting pressure of preferably 0.3 kN or more, more preferably 0.4 kN or more, even more preferably 0.5 kN or more, even more preferably 0.6 kN or more, and preferably less than 1.0 kN, more preferably 0.9 kN or less. By using a tableting pressure in compression molding that is equal to or greater than the above lower limit, the strength of the tablet is further improved, and the tablet is prevented from disintegrating during production, and the powdered metal iodide is prevented from adhering to the upper punch 101 and the lower punch 103, which in turn prevents the black material from falling into the mortar 102 and becoming mixed into the metal iodide tablet. In addition, by controlling the tableting pressure in the compression molding to the above upper limit or less, In this way, the strength of the tablet becomes more appropriate, the solubility is improved, and the workability during each use can be improved.

[0019] In addition, the above-mentioned compression molding step preferably includes a pre-pressing step and a main pressing step in this order. The tableting pressure in the above-mentioned compression molding step is the pressure in the main pressing step. After the pre-pressing step, it is preferable that the pressure is released once and then the main pressing step is performed. The pre-pressing step and the main pressing step are performed, for example, once each. By carrying out the pre-pressing step before the main pressing step, the powder of the metal iodide can be compressed to a certain degree before the main pressing step, and scattering of the powder of the metal iodide can be prevented more effectively than when only the main pressing step is carried out. Also, a stable tablet with less variation in strength can be obtained with a smaller main pressing pressure.

[0020] It is preferable that oil is applied to the surfaces of the upper punch 101 and the lower punch 103 of the above-mentioned tablet press. This further reduces metal friction between the upper punch 101 and the upper holder hole (not shown) in which the upper punch 101 is placed due to the up and down movements of the upper punch 101 and the lower punch 103, and further prevents metal powder of the tablet press scraped off by friction from being mixed into the metal iodide tablets. In the above process of compression molding the powdered metal iodide, it is preferable to periodically apply oil to the surfaces of the upper punch 101 and the lower punch 103 in order to more effectively suppress friction between the upper punch 101 and the lower punch 103. General-purpose machine lubricating oils such as hydrocarbon oils can be used as the oil to be applied to the surfaces of the upper punch 101, the lower punch 103, and the mortar 102. Examples of commercially available oils that can be applied to the upper punch 101 include food-grade synthetic gear oil, and examples of commercially available oils that can be applied to the lower punch 103 include gear oil 150.

[0021] The compression molding step is preferably carried out at a certain humidity or less. The compression molding step is preferably carried out in a humidity environment of 60% RH or less, more preferably 55% RH or less, even more preferably 50% RH or less, and even more preferably 45% RH or less. By keeping the humidity in the compression molding process at or below the upper limit, adhesion of the powder to the upper punch 101 can be further suppressed, and thus inclusion of black substances in the tablets can be further suppressed. Environmental humidity control during the compression molding process refers to humidity control of the environment around the tablet press, and may involve humidity control of the entire room in which the tablet press is installed, or, if the tablet press is covered by a glass or other cover and humidity control is possible only inside the cover, humidity control may be performed only inside the cover.

[0022] The method for producing metal iodide tablets of this embodiment may further include, prior to the above-mentioned compression molding step, a step of drying the powder of metal iodide and a step of feeding the powder into a tablet press. Between the step of drying the powder of metal iodide and the step of feeding the powder into a tablet press, the moisture content of the powder measured by Karl Fischer coulometric titration is preferably 500 ppm or less, more preferably 400 ppm or less, even more preferably 300 ppm or less, even more preferably 250 ppm or less, even more preferably 200 ppm or less, even more preferably 150 ppm or less, even more preferably 100 ppm or less, even more preferably 90 ppm or less, even more preferably 50 ppm or less, even more preferably 20 ppm or less. There is no lower limit for the moisture content of the powder measured by Karl Fischer coulometric titration, but for example, it may be 1 ppm or more, 5 ppm or more, or 10 ppm or more, based on the total mass of the powder. By making the moisture content of the powder of the metal iodide equal to or less than the upper limit, adhesion of the powder to the upper punch 101 can be further suppressed, and thus contamination of the metal iodide tablets with black substances can be further suppressed. Also, caking of the metal iodide tablets can be further suppressed.

[0023] The moisture content of the metal iodide powder is measured as follows. 2 g of powder of metal iodide is placed in a moisture vaporizer and heated at 345°C. The amount of moisture generated is measured by coulometric titration in accordance with JIS K 0113:2005 using a Karl Fischer moisture meter and Karl Fischer reagent, and the moisture content (ppm) is calculated using the following formula (3). Equation (3): Moisture content (ppm) = measured moisture content (mg) / mass of metal iodide powder (kg)

[0024] In the step of drying the metal iodide powder, the metal iodide powder is dried at a temperature of preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, even more preferably 130°C or higher, and preferably 180°C or lower, more preferably 160°C or lower, even more preferably 150°C or lower. In the step of drying the metal iodide powder, the drying time of the powder is preferably 10 minutes or more, more preferably 30 minutes or more, and preferably 200 minutes or less, more preferably 150 minutes or less. By setting the drying temperature and drying time of the metal iodide powder to not less than the above lower limit values, the moisture content of the metal iodide powder can be further reduced, the adhesion of the powder to the upper punch 101 can be further suppressed, and the inclusion of black substances can be further suppressed. In addition, by setting the drying temperature and drying time of the metal iodide powder to not more than the above upper limit values, the productivity of metal iodide tablets can be further improved.

[0025] The method for producing a metal iodide tablet of this embodiment may further include a step of removing the fraction on a 4-mesh sieve from the powder of metal iodide before the compression molding step. By removing the fraction on a 4-mesh sieve from the powder of metal iodide, it becomes easier to feed the powder into a tablet press, and productivity can be improved.

[0026] <Metal iodide tablets> The metal iodide tablet of this embodiment is a metal iodide tablet manufactured by the above-mentioned method for manufacturing a metal iodide tablet of this embodiment. Since the metal iodide tablet of this embodiment is manufactured by the manufacturing method of the metal iodide tablet of this embodiment described above, the inclusion of black substances is further suppressed.

[0027] The metal iodide tablet of this embodiment preferably contains one selected from the group consisting of potassium iodide, sodium iodide, lithium iodide, rubidium iodide, cesium iodide, calcium iodide, magnesium iodide, strontium iodide, barium iodide, zinc iodide, ammonium iodide, and aluminum iodide, more preferably contains one selected from the group consisting of potassium iodide, sodium iodide, and lithium iodide, and even more preferably contains potassium iodide.

[0028] The metal iodide tablet of the present embodiment is preferably cylindrical. By being cylindrical, the specific surface area of ​​the metal iodide tablet can be made smaller, and thus the moisture absorption of the metal iodide tablet can be further suppressed.

[0029] From the viewpoint of further improving the strength of the tablet, the diameter of the metal iodide tablet is preferably 2.0 mm or more, more preferably 3.0 mm or more, even more preferably 3.5 mm or more, even more preferably 4.0 mm or more, and even more preferably 4.5 mm or more, and from the viewpoint of further improving productivity and making the tablet more compact, the diameter is preferably 4.9 mm or less, more preferably 4.8 mm or less.

[0030] The height of the metal iodide tablet is preferably 3 mm or more, more preferably 4 mm or more, even more preferably 5 mm or more, and even more preferably 6 mm or more, from the viewpoint of further improving the strength of the tablet, and is preferably 10 mm or less, more preferably 9 mm or less, and even more preferably 8 mm or less, from the viewpoint of further improving productivity and making the tablet more compact.

[0031] From the viewpoint of further improving the strength of the tablet, the mass per metal iodide tablet is preferably 0.10 g or more, more preferably 0.15 g or more, even more preferably 0.20 g or more, and even more preferably 0.25 g or more, and from the viewpoint of further improving productivity and handleability, the mass per tablet is preferably 0.50 g or less, more preferably 0.45 g or less, even more preferably 0.40 g or less, and even more preferably 0.35 g or less.

[0032] The bulk density of the metal iodide tablet is preferably 1.0 g / cm from the viewpoint of further improving packing properties. 3 More preferably, 1.2 g / cm 3 More preferably, 1.4 g / cm 3 From the viewpoint of further suppressing caking, it is preferably 1.8 g / cm 3 Less than or equal to 1.6 g / cm 3 The following is the result. The bulk density of a metal iodide tablet is measured as follows: The diameter and height of one metal iodide tablet are measured, and the volume (cm 3 Next, place a metal iodide tablet in the measuring cylinder, measure its mass (g), and subtract the mass (g) of the measuring cylinder, which was previously measured, to obtain the mass (g) of the metal iodide tablet. The mass (g) and volume (cm) of the resulting metal iodide tablet 3 ) and calculate the bulk density (g / cm3) using the following formula (4): 3 ) is measured. Equation (4): Bulk density (g / cm 3 ): Mass of metal iodide tablet (g) / Volume of metal iodide tablet (cm 3 )

[0033] The density of the metal iodide tablet is preferably 1.0 g / cm from the viewpoint of further improving the strength of the tablet. 3 More preferably, 1.3 g / cm 3 More preferably, 1.5 g / cm 3 More preferably, 1.8 g / cm 3 From the viewpoint of further improving the solubility, it is preferably 4.0 g / cm 3 Less than or equal to 3.5 g / cm 3 More preferably, 3.0 g / cm 3 The following is the result. The density of the metal iodide tablet can be adjusted by adjusting the tableting pressure (main pressure) when the powder of the metal iodide is compressed to produce tablets in the manufacturing method of the metal iodide tablet. Specifically, the density of the metal iodide tablet becomes higher when the tableting pressure is increased, and the density of the metal iodide tablet becomes lower when the tableting pressure is decreased.

[0034] The specific surface area of ​​the metal iodide tablet is preferably 2.0 cm from the viewpoint of further improving moldability. 2 / g or more, more preferably 2.5 cm 2 / g or more, more preferably 3.0 cm 2 / g or more, more preferably 3.2 cm 2 / g or more, and from the viewpoint of further suppressing the moisture absorption of the metal iodide, it is preferably 6.0 cm 2 / g or less, more preferably 5.5 cm 2 / g or less, more preferably 5.0 cm 2 / g or less. The specific surface area of ​​the metal iodide tablet is calculated by the following formula (2). Equation (2): Specific surface area (cm 2 / g) = surface area per metal iodide tablet (cm 2 ) / mass of one metal iodide tablet (g)

[0035] From the viewpoint of further reducing the content of impurities, the content of the lubricant in the metal iodide tablet is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less, when the entire metal iodide tablet is taken as 100% by mass.

[0036] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. Furthermore, the present invention is not limited to the above-described embodiment, and modifications and improvements that do not impair the effects of the present invention are included in the present invention. EXAMPLES

[0037] Hereinafter, the present embodiment will be described in detail with reference to examples, etc. However, the present embodiment is not limited to the description of these examples.

[0038] <Production of metal iodide tablets> Example 1 The powder of potassium iodide was dried in a dryer at a temperature of 140°C for 2 hours. The moisture content of the powder after drying was 20 ppm. This powder was sieved through a 4-mesh sieve, and the fraction that fell under the 4-mesh sieve was collected. The fraction that fell under the 4-mesh sieve of the obtained powder was put into the hopper of a tablet press shown in Figure 1 (with a rubber cap installed on the upper punch. The upper punch, mortar, and lower punch were set so that the resulting tablet diameter was 4.8 mm. The mortar surface was nitrided. The surfaces of the upper and lower punches were coated with oil), and the powder was compressed under conditions of humidity of 60% RH or less and main pressure of 0.82 kN to obtain potassium iodide tablets. Comparative Example 1 Potassium iodide tablets were obtained in the same manner as in Example 1, except that a tablet press without a cap on the upper punch was used.

[0039] <Evaluation of black matter contamination in potassium iodide tablets> The potassium iodide tablets of Example 1 and Comparative Example 1 were visually evaluated for the inclusion of black substances in the potassium iodide tablets according to the following criteria. (standard) A (good): There were no black spots on the tablets and no black matter was mixed in. B (Poor): One or more black dots were found on the tablet, and black matter was found to be mixed in.

[0040] [Table 1] [Explanation of symbols]

[0041] 101: Upper pestle 102: Mortar 103: Lower pestle 104: Cap

Claims

1. 1. A method for producing a metal iodide tablet, comprising: The method includes a step of compressing and molding a powder of a metal iodide using a tablet press, A method for producing metal iodide tablets, wherein the tablet press is equipped with an upper punch, a mortar, and a lower punch in that order, and the upper punch has a cap for preventing the metal iodide powder from falling into the inside of the mortar.

2. The method for producing metal iodide tablets according to claim 1, wherein the compression molding is performed by applying a tableting pressure of 0.3 kN or more and less than 1.0 kN to the powder of metal iodide.

3. The method for producing metal iodide tablets according to claim 1 or 2, wherein the tablet press is provided with an upper punch, a mortar and a lower punch made of metal, and one or more surfaces selected from the group consisting of the upper punch, the mortar and the lower punch are nitrided.

4. The method further includes a step of drying the powder and a step of feeding the powder into the tablet press before the step of compressing, 3. The method for producing metal iodide tablets according to claim 1 or 2, wherein the moisture content of the powdery material measured by Karl Fischer coulometric titration according to the following <Moisture content> between the step of drying the powdery material and the step of feeding the powdery material into the tablet press is 500 ppm or less relative to the total mass of the powdery material. <Water content> 2 g of the powder was placed in a moisture vaporizer and heated at 345° C. The amount of moisture generated by heating was measured by coulometric titration in accordance with JIS K 0113:2005 using a Karl Fischer moisture meter and a Karl Fischer reagent, and the moisture content (ppm) was calculated using the following formula (3). Equation (3): Moisture content (ppm) = Measured moisture content (mg) / Mass of the powder (kg)

5. The method for producing metal iodide tablets according to claim 4, wherein in the step of drying the powder, the powder is dried at a temperature of 100°C or higher and 180°C or lower.

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