Highly oil-absorptive sodium bicarbonate powder

Abstract

This sodium bicarbonate powder exhibits an oil absorption amount of at least 40 mL / 100 g and / or has an apparent density of at most 0.32 g / mL. In the sodium bicarbonate powder, the crystallite size of the (210) plane is preferably at most 75 nm, and the crystallite size of the (121) plane is preferably at most 70 nm. The ratio (D210 / D121) of the crystallite size (D210) of the (210) plane with respect to the crystallite size (D121) of the (121) plane is preferably 0.60-1.00.

Description

High oil absorption sodium bicarbonate powder

[0001] The present invention relates to a high oil absorption sodium bicarbonate powder. This application claims priority to Japanese Patent Application No. 2024-040356, filed on March 14, 2024, the contents of which are incorporated herein by reference.

[0002] Sodium bicarbonate is used in a wide range of applications, including food, feed, deodorants, pharmaceuticals, and incineration exhaust gas treatment. Sodium bicarbonate is handled as a powder, but it has the problem of caking easily during storage. Caking can cause problems when removing the powder from tanks during transportation or silos, or when weighing it. Therefore, methods for preventing the caking of sodium bicarbonate powder have been proposed.

[0003] Patent Document 1 discloses anti-caking sodium bicarbonate in which part or all of the sodium carbonate present on the surface of sodium bicarbonate particles is sodium sesquicarbonate, and such sodium bicarbonate is obtained by treating sodium bicarbonate particles at a relative humidity of 50 to 90% and a temperature of 20 to 70°C.

[0004] Japanese Patent Application Laid-Open No. 2003-104722

[0005] In Patent Document 1, anti-caking sodium bicarbonate is obtained by changing the surface composition of sodium bicarbonate particles once obtained. However, to convert sodium bicarbonate to sodium sesquicarbonate, long-term treatment at high humidity is required, and if the treatment is performed at high temperature and humidity for too long, the entire particle surface becomes sodium carbonate, changing the chemical properties. Furthermore, even with the anti-caking sodium bicarbonate of Patent Document 1, the improvement in caking resistance (moisture resistance) is still insufficient. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sodium bicarbonate powder that has excellent moisture resistance and deodorizing properties.

[0006] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by adjusting the oil absorption or apparent density of sodium bicarbonate powder, and have thus completed the present invention. The present invention encompasses the following aspects. [1] Sodium bicarbonate powder having an oil absorption of 40 mL / 100 g or more. [2] The sodium bicarbonate powder according to [1], wherein the crystallite size of the (210) plane is 75 nm or less and the crystallite size of the (121) plane is 70 nm or less. [3] The sodium bicarbonate powder according to [1] or [2], wherein the ratio (D210 / D121) of the crystallite size of the (210) plane (D210) to the crystallite size of the (121) plane (D121) is 0.60 to 1.00. [4] Sodium bicarbonate powder having an apparent density of 0.32 g / mL or less. [5] Sodium bicarbonate powder according to [4], wherein the crystallite size of the (210) plane is 75 nm or less and the crystallite size of the (121) plane is 70 nm or less. [6] Sodium bicarbonate powder according to [4] or [5], wherein the ratio (D210 / D121) of the crystallite size of the (210) plane (D210) to the crystallite size of the (121) plane (D121) is 0.60 to 1.00. [7] A method for producing sodium bicarbonate, comprising supplying fine bubbles of a gas containing carbon dioxide to an aqueous solution of sodium hydroxide or sodium carbonate to obtain sodium bicarbonate. [8] A method for producing sodium bicarbonate, comprising spraying an aqueous solution of sodium bicarbonate with a spray dryer to obtain sodium bicarbonate. [9] Sodium bicarbonate powder having an oil absorption of 40 mL / 100 g or more and an apparent density of 0.32 g / mL or less.

[10] The sodium bicarbonate powder according to [9], wherein the crystallite size of the (210) plane is 75 nm or less and the crystallite size of the (121) plane is 70 nm or less.

[11] The sodium bicarbonate powder according to [9] or

[10] , wherein the ratio (D210 / D121) of the crystallite size of the (210) plane (D210) to the crystallite size of the (121) plane (D121) is 0.60 to 1.00.

[12] The sodium bicarbonate powder according to any one of [1] to [6],

[10] and

[11] , wherein the oil absorption is 100 mL / 100 g or more.

[13] The sodium bicarbonate powder according to any one of [1] to [6],

[10] and

[11] , having an apparent density of 0.10 g / mL or less.

[14] The sodium bicarbonate powder according to any one of [1] to [6] and

[10] to

[13] , having an average particle size (d50) of 12 μm to 50 μm.

[15] The sodium bicarbonate powder according to any one of [1] to [6] and

[10] to

[14] , having a crystallite size of the (210) plane of 60 nm or less or 45 nm or less and a crystallite size of the (121) plane of 55 nm or less.

[0007] According to the present invention, it is possible to provide a sodium bicarbonate powder that can be produced by a simple method and has excellent moisture resistance and deodorizing properties.

[0008] Fig. 1 is a schematic diagram showing an example of an apparatus for producing sodium bicarbonate powder of the present invention. Fig. 2 is a schematic diagram showing another example of an apparatus for producing sodium bicarbonate powder of the present invention. Fig. 3 is a schematic diagram showing yet another example of an apparatus for producing sodium bicarbonate powder of the present invention. Fig. 4 is a diagram for explaining the procedure of a moisture resistance test method in the examples. Fig. 5 is a diagram for explaining the procedure of a moisture resistance test method in the examples.

[0009] In this specification, a numerical range expressed as "to" means a numerical range in which the numerical values ​​before and after "to" are the lower and upper limits.

[0010] The present invention will be described below, but the examples in the following description do not limit the present invention. <Sodium Bicarbonate Powder> The sodium bicarbonate powder of this embodiment has an oil absorption of 40 mL / 100 g or more or an apparent density of 0.32 g / mL or less. A preferred example of this embodiment is one in which the oil absorption is 40 mL / 100 g or more and the apparent density is 0.32 g / mL or less. <Oil Absorption> The oil absorption is preferably 60 mL / 100 g or more, and more preferably 100 mL / 100 g or more. By having an oil absorption equal to or greater than the lower limit, sodium bicarbonate powder with excellent moisture resistance and deodorizing properties can be obtained. There are no upper limits for the oil absorption, but it is usually sufficient to set it to 200 mL / 100 g or less. The oil absorption is a value measured in accordance with JIS K5101-13-1.

[0011] <Apparent Density> The apparent density is preferably 0.25 g / mL or less, and more preferably 0.10 g / mL or less. By having an apparent density equal to or less than the upper limit, a sodium bicarbonate powder with excellent moisture resistance and deodorizing properties can be obtained. The lower limit of the apparent density is not limited, but it is usually sufficient to set it to 0.04 g / mL or more. The apparent density is a value measured using an apparent density measuring instrument in accordance with JIS K5101-12-1.

[0012] <Crystallite Size> The sodium bicarbonate powder of this embodiment preferably has a crystallite size of 75 nm or less on the (210) plane and a crystallite size of 70 nm or less on the (121) plane. The crystallite size of the (210) plane is more preferably 60 nm or less, and even more preferably 45 nm or less. By having the crystallite size of the (210) plane be equal to or less than the upper limit, the moisture resistance and deodorizing properties of the sodium bicarbonate powder can be further improved. The lower limit of the crystallite size of the (210) plane is not particularly limited, but is usually set to 20 nm or more. The crystallite size of the (121) plane is more preferably 55 nm or less, and even more preferably 40 nm or less. By having the crystallite size of the (121) plane be equal to or less than the upper limit, the moisture resistance and deodorizing properties of the sodium bicarbonate powder can be further improved. The lower limit of the crystallite size of the (121) plane is not particularly limited, but is usually set to 15 nm or more. Furthermore, the ratio (D210 / D121) of the crystallite size (D210) of the (210) plane to the crystallite size (D121) of the (121) plane is preferably 0.60 to 1.00, more preferably 0.70 to 0.90. When this ratio (D210 / D121) is within the above range, the moisture resistance and deodorizing properties of the sodium bicarbonate powder can be further improved. The crystallite sizes of the (210) plane and the (121) plane can be determined by the X-ray diffraction pattern of NaHCO ３Among the peaks derived from the above, the diffraction peaks due to the (210) and (121) planes are selected as peaks that do not overlap with other peaks and have relatively high relative intensities, and the crystallite size for each crystal plane is determined using the following Scherrer equation: D = Kλ / {(B - B) cos θ} where D is the crystallite size (nm) and K is the Scherrer constant, 0.89. λ is the wavelength (nm) of the X-ray, with 0.1542 nm for Cu-Kα radiation. B is the full width at half maximum (rad) of each diffraction peak, and B is an instrumental function, which is the full width at half maximum (rad) of the peak obtained by measuring an α-alumina sintered body with a crystallite size of 1 μm or more. θ is the diffraction angle (rad) of each diffraction peak. It is preferable that the full width at half maximum (rad) is 0.2 to 0.3.

[0013] <d50 of Sodium Bicarbonate Powder> The average particle diameter (d50) of the sodium bicarbonate powder of this embodiment is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, and even more preferably 12 μm to 50 μm. When the average particle diameter is within this range, the moisture resistance and deodorizing properties of the sodium bicarbonate powder are more easily improved. The d50 of the sodium bicarbonate powder is the volume-based cumulative 50% diameter (median diameter) determined by laser diffraction / scattering. That is, the particle size distribution is measured by laser diffraction / scattering, a cumulative curve is determined with the total volume of the particle population set to 100%, and the d50 is the particle diameter at the point on the cumulative curve where the cumulative volume is 50%.

[0014] <<Method for Producing Sodium Bicarbonate Powder>> The sodium bicarbonate powder of the present invention can be obtained, for example, by two methods described below. <First Method> The first method involves supplying carbon dioxide-containing gas bubbles to an aqueous solution of sodium hydroxide to carbonate and bicarbonate the solution, thereby obtaining sodium bicarbonate. The bubbles are preferably fine bubbles, as described below. That is, it is preferable to generate fine bubbles of carbon dioxide-containing gas and supply them to an aqueous solution of sodium hydroxide or an aqueous solution of sodium carbonate. The concentration of sodium hydroxide in the aqueous solution is not particularly limited as long as it is equal to or less than the saturated concentration of sodium hydroxide, but is preferably 4 to 20%, and more preferably 8 to 15%. A concentration equal to or greater than the lower limit described above is preferable because the aqueous sodium bicarbonate solution obtained by carbonation and bicarbonation becomes supersaturated, causing sodium bicarbonate to precipitate and form a sodium bicarbonate slurry, which can then be filtered and dried to obtain sodium bicarbonate powder. A concentration equal to or less than the upper limit described above has the advantage that the viscosity of the sodium bicarbonate slurry is not too high and is easy to handle. Fine bubbles are a general term for microbubbles with diameters of 1 to 100 μm and nanobubbles with diameters of less than 1 μm. When a large number of microbubbles are generated in water, they appear as cloudy white water. Nanobubbles, on the other hand, are so small that the water remains transparent. By converting carbon dioxide-containing gas into fine bubbles, the gas-liquid interface with an aqueous solution of sodium hydroxide or sodium carbonate increases, accelerating the dissolution rate of carbon dioxide. This allows almost all of the supplied carbon dioxide to react with sodium hydroxide or sodium carbonate, eliminating carbon dioxide loss and enabling extremely rapid crystallization of sodium bicarbonate. By crystallizing sodium bicarbonate at an extremely high speed, microcrystalline sodium bicarbonate precipitates, resulting in sodium bicarbonate powder with high oil absorption and low apparent density.

[0015] Such fine bubble generating devices are not particularly limited, and examples include the following: (Example 1) A device that supplies gas to the suction side of a pressure pump and converts the gas into fine bubbles using a mixing blade rotating at high speed inside the pressure pump. A specific example is the "Vortex Turbo Mixer Pump" (product name) manufactured by Nikuni Co., Ltd. (Example 2) A device that creates a low-pressure area in a liquid flow by using the Venturi effect (narrowing the flow path of a pressurized liquid to increase the flow rate and create a low-pressure area), and then supplies gas to that area to generate fine bubbles. Specific examples include the "YJ Nozzle" (product name) manufactured by Envirovision Co., Ltd. and the "Aqua Transfer Nozzle" (product name) manufactured by Water Navi Co., Ltd. (Example 3) A device that creates a negative pressure area in the center by spraying water radially from a rapidly rotating disk, and then sucks in gas to generate fine bubbles. A specific example is the "Spinor" (product name) manufactured by Water Navi Co., Ltd.

[0016] The temperature of the aqueous sodium hydroxide solution or aqueous sodium carbonate solution when supplying fine bubbles of gas containing carbon dioxide is not particularly limited, but is preferably 0°C to 80°C. The lower the temperature, the greater the solubility of carbon dioxide in the aqueous sodium hydroxide solution or aqueous sodium carbonate solution, but temperatures above 0°C are preferred because there is no risk of freezing. On the other hand, the higher the temperature, the less the solubility of carbon dioxide in the aqueous sodium hydroxide solution or aqueous sodium carbonate solution, and temperatures below 80°C are preferred because the rate of alkali metal carbonate production is less likely to slow. The temperature of the aqueous solution is more preferably 20 to 60°C, and even more preferably 30 to 50°C.

[0017] The gas containing carbon dioxide is not particularly limited as long as the carbon dioxide concentration is 10% by volume or more, and examples thereof include not only mixed gases of carbon dioxide with air or nitrogen gas, such as exhaust gas from a combustion furnace, exhaust gas from a glass melting furnace, and gas generated by neutralizing carbonates, but also high-purity carbon dioxide gas, etc. The carbon dioxide concentration is preferably 30% by volume or more, more preferably 50% by volume or more.

[0018] Furthermore, the carbon dioxide-containing gas bubbles preferably have a d50 of 100 μm or less and a d90 of 150 μm or less. Bubbles of this size can be obtained by appropriately adjusting the conditions of a known fine bubble preparation method. The bubble size can be measured, for example, using a particle size analyzer (product name: Particle Track) using FBRM (focused beam reflectance measurement) manufactured by Mettler Toledo K.K. In this specification, the bubble size distribution is expressed as the 10% diameter (d10), 50% diameter (median diameter, d50), and 90% diameter (d90) in the cumulative distribution curve of bubble volume relative to bubble size. From the viewpoint of further ensuring the effects of the present invention, the d50 is preferably 50 to 90 μm, more preferably 60 to 80 μm, and the d90 is preferably 100 to 150 μm, more preferably 100 to 130 μm. By adjusting the bubble size of the carbon dioxide-containing gas within this range, the dissolution rate of carbon dioxide can be increased, and crystallization of sodium bicarbonate can be carried out very quickly, resulting in the precipitation of fine crystals of sodium bicarbonate, and the production of sodium bicarbonate powder with a high oil absorption and a low apparent density. The time required for crystallization of sodium bicarbonate from an aqueous sodium carbonate solution is preferably 12 hours or less, more preferably 6 hours or less, and even more preferably 3 hours or less.

[0019] As described above, sodium bicarbonate slurry is obtained by supplying fine bubbles of carbon dioxide-containing gas to an aqueous solution of sodium hydroxide or sodium carbonate. This slurry is then filtered using a filter such as a centrifugal dehydrator to produce a sodium bicarbonate cake, which is then dried and pulverized to obtain sodium bicarbonate powder.

[0020] The first method will be described below with reference to Figures 1 and 2, but this is merely an example and the present invention is not limited by this example. Figure 1 is a schematic diagram showing an example of an apparatus for producing sodium bicarbonate powder of the present invention (hereinafter also referred to as a "sodium bicarbonate powder production apparatus") that can be used to implement the first method (hereinafter also referred to as an "apparatus of the first embodiment"). The sodium bicarbonate powder production apparatus 100 illustrated in Figure 1 is an apparatus that precipitates sodium bicarbonate from an aqueous sodium carbonate solution using a "vortex turbo mixer pump" (product name) manufactured by Nikuni Co., Ltd. as a device for generating fine bubbles of gas containing carbon dioxide, but the present invention is not limited by this example.

[0021] The sodium bicarbonate powder manufacturing apparatus 100 includes a crystallization tank 1, which is equipped with an agitator 2. Liquid 3 in the crystallization tank 1 is initially an aqueous sodium carbonate solution. This aqueous sodium carbonate solution is circulated through the crystallization tank 1 via a circulation pipe 5 using a vortex turbo mixer pump 4, while finely bubbled carbon dioxide is introduced into the suction side of the vortex turbo mixer pump 4 through a carbon dioxide-containing gas supply pipe 6. As the carbon dioxide-containing gas is introduced, the pH of the liquid 3 in the crystallization tank decreases, and sodium bicarbonate precipitates, causing the liquid to become cloudy. When the pH of the liquid 3 in the crystallization tank finally reaches 8.5 or below, the supply of the carbon dioxide-containing gas is stopped, yielding a sodium bicarbonate slurry. The resulting sodium bicarbonate slurry is sent to a centrifugal dehydrator 8 via a feed pipe 7 and centrifuged to yield a sodium bicarbonate cake 10, with the remainder remaining as a filtrate 9. The sodium bicarbonate cake 10 is dried in a drying device 11 to yield sodium bicarbonate powder 12.

[0022] Fig. 2 is a schematic diagram showing another example of an apparatus that can be used to carry out the first method (hereinafter, sometimes referred to as "the apparatus of the second embodiment"). The sodium bicarbonate powder manufacturing apparatus 200 shown in Fig. 2 is an apparatus that uses a "YJ Nozzle" (product name) manufactured by Envirovision Co., Ltd. as an apparatus for generating fine bubbles of a gas containing carbon dioxide to precipitate sodium bicarbonate from an aqueous solution of sodium carbonate, but the present invention is not limited to this example.

[0023] The apparatus of the second embodiment differs from the apparatus of the first embodiment in that it uses a YJ nozzle instead of a vortex turbo mixer pump to create fine bubbles of gas containing carbon dioxide. Liquid 3 in crystallization tank 1 is supplied to YJ nozzle 14 by magnetic pump 13. Gas containing carbon dioxide is supplied to the center of YJ nozzle 14 through supply piping 6 and converted into fine bubbles within the YJ nozzle. As a result, sodium bicarbonate slurry is obtained in crystallization tank 1, just like in the apparatus of the first embodiment.

[0024] <Second Method> The second method for obtaining sodium bicarbonate powder of the present invention involves spraying an aqueous solution of sodium bicarbonate using a spray dryer to obtain sodium bicarbonate powder. The spray dryer conditions can be, for example, as follows: an air inlet temperature of generally 100 to 200°C, preferably 110 to 150°C; an air outlet temperature of generally 60 to 150°C, preferably 80 to 130°C; an atomizing air pressure of generally 0.4 to 1.0 MPa, preferably 0.5 to 0.8 MPa; and an air flow rate of generally 3 to 20 L / min, preferably 6 to 15 L / min. An air inlet temperature above the lower limit described above is preferred because it allows sufficient removal of water from the aqueous solution of sodium bicarbonate, preventing precipitation of sodium bicarbonate powder and preventing the resulting sodium bicarbonate powder from becoming damp. An air inlet temperature below the upper limit described above is preferred because it prevents thermal decomposition of sodium bicarbonate.

[0025] The second method will be described below with reference to Fig. 3, but this is merely an example and the present invention is not limited by this example. Fig. 3 is a schematic diagram showing an example of a sodium bicarbonate powder manufacturing apparatus (hereinafter, also referred to as "the apparatus of the third embodiment") used in the second method. The sodium bicarbonate powder manufacturing apparatus 300 shown in Fig. 3 is an apparatus for spraying an aqueous solution of sodium bicarbonate with a spray dryer to obtain sodium bicarbonate powder, but the present invention is not limited by this example.

[0026] A liquid 16 to be sprayed, which is contained in a container 15, is supplied to a two-fluid nozzle 18 by a pump 17. Hot air 19 is also supplied to the two-fluid nozzle 18, and the liquid 16 to be sprayed is sprayed into a spray cylinder 20 by the hot air 19. The sprayed liquid is dried in the spray cylinder 20 to become sodium bicarbonate powder. This sodium bicarbonate powder is introduced into a cyclone 21 together with the hot air and is recovered as sodium bicarbonate powder 23 in a recovery container 22. The air that has passed through the cyclone 21 is filtered by a filter 24 and released into the atmosphere.

[0027] The sodium bicarbonate powder and the method for producing the same of the present invention have been described above. However, the present invention is not limited to the configurations described in the above embodiments, and the configurations can be appropriately changed within the scope of the invention.

[0028] The sodium bicarbonate powder of the present invention is not particularly limited in its applications, but because of its high reactivity with gases, it is suitable for use as a deodorizer, a neutralizer for acidic substances, and a detoxifier for incineration exhaust gases. In addition, because of its excellent moisture resistance in high humidity environments and its resistance to caking, it is also suitable as an emergency neutralizer, kitchen detergent, etc.

[0029] The present invention will be described in more detail below with reference to examples, but is not limited to these. Unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0030] Examples 1 to 3 are working examples, and Examples 4 to 6 are comparative examples.

[0031] <<Measurement Methods and Evaluation Methods>> (Carbon Dioxide Utilization Rate) In the first method for producing sodium bicarbonate powder of the present invention described above (using the apparatuses of the first and second embodiments), the carbon dioxide utilization rate (%) during sodium bicarbonate precipitation was determined as the ratio, expressed as a percentage, of the calculated amount of carbon dioxide gas (B) required to convert all of the sodium carbonate in the aqueous sodium carbonate solution used into sodium bicarbonate to the amount of carbon dioxide gas (A) actually supplied for sodium bicarbonate precipitation. Carbon dioxide utilization rate (%) during sodium bicarbonate precipitation = calculated amount of carbon dioxide gas required to convert all of the sodium carbonate into sodium bicarbonate (B, unit: L) / amount of carbon dioxide gas actually supplied (A, unit: L) × 100

[0032] (d50 of sodium bicarbonate powder) Using a particle size distribution measuring device, Microtrac FRA model, manufactured by Nikkiso Co., Ltd., the particle size distribution of sodium bicarbonate particles dispersed in a mixed solvent (methanol = 11%, ethanol = 88%, isopropanol = 1%) was measured, and the median diameter d50 was determined.

[0033] (Oil absorption of sodium bicarbonate powder) The oil absorption was measured in accordance with JIS K5101-13-1. Specifically, boiled linseed oil was added to the sodium bicarbonate powder while kneading until the sodium bicarbonate powder was completely formed into a single mass. The oil absorption was expressed as the volume of boiled linseed oil per 100 g of sodium bicarbonate when the entire sample was completely formed into a single mass.

[0034] (Apparent Density of Sodium Bicarbonate Powder) The apparent density was measured using an apparent density measuring instrument according to the provisions of JIS K5101-12-1.

[0035] (Crystallite size of sodium bicarbonate powder) Powder X-ray diffraction was performed using an X-ray diffractometer (model: SmartLab) manufactured by Rigaku Corporation. The measurement conditions were: output: 45 kV-200 mA, scanning speed: 20° / min, step width: 0.02°, scanning range: 10 to 80°. The crystallite size of NaHCO ３Among the peaks derived from the above, the diffraction peaks due to the (210) and (121) planes were selected as peaks that did not overlap with other peaks and had relatively high relative intensities, and the crystallite size for each crystal plane was calculated using the following Scherrer equation: D = Kλ / {(B - B) cos θ} where D is the crystallite size (nm) and K is the Scherrer constant, 0.89. λ is the wavelength (nm) of the X-rays, and 0.1542 nm for Cu-Kα radiation was used. B is the full width at half maximum (rad) of each diffraction peak, and B is an instrumental function, which was the full width at half maximum (rad) of the peak obtained by measuring an α-alumina sintered body with a crystallite size of 1 μm or more. θ is the diffraction angle (rad) of each diffraction peak.

[0036] (Moisture Resistance of Sodium Bicarbonate Powder) Figures 4-1 and 4-2 show the moisture resistance test method. First, as shown in Figure 4-1, 30 g of sodium bicarbonate powder 26 was placed in a polystyrene resin container 25 (inner diameter: 15 cm, depth: 9 cm) and allowed to stand for 72 hours in a desiccator containing silica gel to initialize the sodium bicarbonate powder. The environment inside the desiccator was a temperature of 25±1°C and a humidity of 23±1% RH. Next, the container containing the sodium bicarbonate powder was removed from the desiccator and stored in a thermo-hygrostat. The thermo-hygrostat was maintained at a temperature of 25±1°C and a humidity of 88±3% RH. The sodium bicarbonate powder was then removed from the thermo-hygrostat every 12 hours, and the caking properties of the sodium bicarbonate powder were examined. Figure 4-2 shows the caking property test method. The polystyrene resin container containing the sodium bicarbonate powder was rotated at a speed of 15 rpm while tilted approximately 30 degrees from the horizontal. If the sodium bicarbonate powder crumbled and fell, it was not solidified, and the moisture resistance was evaluated as ○. On the other hand, if the sodium bicarbonate powder did not crumble and fell, it was solidified, and the moisture resistance was evaluated as ×.

[0037] (Deodorizing Performance of Sodium Bicarbonate Powder) The deodorizing performance of sodium bicarbonate powder against isovaleric acid, an odor component, was tested using gas chromatography in accordance with the SEK Mark textile product certification standards of the Textile Evaluation Technology Council. Specifically, the test was performed using the following procedure. 1) 0.1 g of sodium bicarbonate powder was placed at the bottom of a 500 mL Erlenmeyer flask. 2) Next, 5 μL of an ethanol solution of isovaleric acid (isovaleric acid concentration: 38 ppm) was dropped into the Erlenmeyer flask. 3) The Erlenmeyer flask was sealed and left at 20°C for 2 hours, after which the gas concentration of isovaleric acid in the Erlenmeyer flask was measured using gas chromatography. 4) The reduction rate (%) of the concentration (unit: ppm) after 2 hours relative to the initial concentration (unit: ppm) of isovaleric acid was calculated using the following formula to determine the deodorizing performance. Deodorizing performance (%) = (initial concentration - concentration after 2 hours) / initial concentration x 100

[0038] Example 1: Sodium bicarbonate powder was synthesized using the apparatus 100 of the first embodiment shown in FIG. 1 . First, 400 g of sodium carbonate powder and 2,000 g of ion-exchanged water were charged into a 6-L crystallization tank 1 and stirred to obtain 2,400 g of a 16.7% sodium carbonate aqueous solution. Next, the vortex turbo mixer pump 4 was started, and the sodium carbonate aqueous solution was circulated through the circulation pipe 5. The vortex turbo mixer pump used was a KTM15ND02S model manufactured by Nikuni Co., Ltd. The circulation flow rate was 20 L / min. Immediately after starting the circulation, carbon dioxide gas was supplied to the intake pipe of the vortex turbo mixer pump 4 at a rate of 1.0 L / min to generate fine bubbles and introduce the carbon dioxide. After 85 minutes, the crystallization tank contained a cloudy sodium bicarbonate slurry with a pH of 8.0. The carbon dioxide utilization rate was 100%. The resulting sodium bicarbonate slurry was filtered in a centrifugal dehydrator 8 to produce a sodium bicarbonate cake 10, which was then dried in a drying apparatus 11 to obtain sodium bicarbonate powder 12. The resulting sodium bicarbonate powder weighed 420 g. It was then pulverized in a hammer mill to a d50 of approximately 10 μm. The resulting sodium bicarbonate powder had a d50 of 8.9 μm and a high oil absorption of 42 mL / 100 g. The apparent density was low at 0.28 g / mL. The crystallite sizes were 82 nm for the (210) plane and 77 nm for the (121) plane. In a moisture resistance test, the product did not caking even after 60 hours of storage in an environment of 25±1°C and 88±3% RH. It also deodorized isovaleric acid by 76%. Various conditions and results are shown in Tables 1 and 2.

[0039] Example 2: Sodium bicarbonate powder was synthesized using the apparatus 200 of the second embodiment shown in FIG. 2. First, 800 g of sodium carbonate powder and 4,000 g of ion-exchanged water were charged into a 6-L crystallization tank 1 and stirred to obtain 4,800 g of a 16.7% sodium carbonate aqueous solution. Next, the magnetic pump 13 was started, and the sodium carbonate aqueous solution was circulated using the circulation piping 5. The magnetic pump used was a stainless steel motor pump, Model MM-254 (product name), manufactured by Maruhachi Pump Manufacturing Co., Ltd. The circulation flow rate was 20 L / min. Immediately after the start of circulation, carbon dioxide gas was supplied to the YJ nozzle 14 at a rate of 1.0 L / min to introduce the carbon dioxide into the fine bubbles. The YJ nozzle used was a YJ-6 inline model (product name) manufactured by Envirovision Co., Ltd. After 169 minutes, the sodium bicarbonate precipitation tank contained a cloudy sodium bicarbonate slurry with a pH of 8.0. The carbon dioxide utilization rate was 100%. The resulting sodium bicarbonate slurry was filtered in a centrifugal dehydrator 8 to produce a sodium bicarbonate cake 10, which was then dried in a drying apparatus 11 to obtain sodium bicarbonate powder 12. The resulting sodium bicarbonate powder weighed 850 g. It was then pulverized in a hammer mill to a d50 of approximately 10 μm. The resulting sodium bicarbonate powder had a d50 of 11.1 μm and a high oil absorption of 46 mL / 100 g. The apparent density was low at 0.29 g / mL. The crystallite sizes were 93 nm for the (210) plane and 85 nm for the (121) plane. The resulting sodium bicarbonate powder also had excellent moisture resistance and deodorizing performance, similar to Example 1. Various conditions and results are shown in Tables 1 and 2.

[0040] Example 3 Sodium bicarbonate powder was synthesized using the apparatus 300 of the third embodiment shown in FIG. 3 . 282 g of sodium bicarbonate powder was added to 3,000 g of ion-exchanged water and stirred to dissolve, yielding an 8.6% sodium bicarbonate aqueous solution 16. A Mini Spray Dryer B-290 manufactured by Nippon Bich Co., Ltd. was used as the spray dryer. The sodium bicarbonate aqueous solution 16 was supplied to a two-fluid nozzle 18 with a 0.7 mm aperture at a rate of 10 g / min, while 150°C hot air 19 was also supplied and sprayed into the spray cylinder 20. Simultaneously with the start of spraying, sodium bicarbonate powder was collected in the collection container 22 below the cyclone 21. After approximately 5 hours, spraying was terminated when the sodium bicarbonate aqueous solution 16 was depleted, and the sodium bicarbonate powder in the collection container was collected. The resulting sodium bicarbonate powder weighed 123 g. Because the d50 was approximately 10 μm, no hammer milling was performed. The resulting sodium bicarbonate powder had a d50 of 14.0 μm and an oil absorption of 125 mL / 100 g, which was very high. The apparent density was 0.08 g / mL, which was very low. The crystallite sizes were very small, with the (210) plane crystallite size being 40 nm and the (121) plane crystallite size being 50 nm. In a moisture resistance test, the powder did not caking even after 84 hours of storage in an environment of 25±1°C and 88±3% RH. It also deodorized 99% of isovaleric acid, demonstrating excellent deodorizing properties. Various conditions and results are shown in Tables 1 and 2.

[0041] (Example 4) The physical properties of general-purpose industrial sodium bicarbonate (product name: KF) manufactured by AGC Corporation were evaluated. The d50 was large at 130.0 μm. The oil absorption was very small at 14 mL / 100 g. The apparent density was very large at 1.12 g / mL. The crystallite sizes were very large, with the (210) plane crystallite size being 149 nm and the (121) plane crystallite size being 157 nm. The moisture resistance was also very poor, with caking occurring after 12 hours. The deodorizing performance was also poor compared to Examples 1 to 3. Various conditions and results are shown in Tables 1 and 2.

[0042] (Example 5) The general-purpose industrial sodium bicarbonate (product name: KF) manufactured by AGC Inc. in Example 4 was pulverized with a hammer mill to a d50 of approximately 10 μm. The d50 was 13.4 μm. The oil absorption was low at 30 mL / 100 g. The apparent density was low at 0.35 g / mL. The crystallite sizes were 93 nm for the (210) plane and 98 nm for the (121) plane. The moisture resistance was also very poor, with caking occurring after 24 hours. The deodorizing performance was also poor compared to Examples 1 to 3. Various conditions and results are shown in Tables 1 and 2.

[0043] (Example 6) The physical properties of commercially available sodium bicarbonate powder made from trona were evaluated. The d50 was 110.9 μm. The oil absorption was small at 29 mL / 100 g. The apparent density was large at 1.09 g / mL. The crystallite sizes were relatively small, with the (210) crystallite size at 88 nm and the (121) crystallite size at 76 nm. The moisture resistance was also very poor, with caking occurring after 12 hours. The deodorizing performance was only 10%, which was significantly worse than that of Examples 1 to 3. The various conditions and results are shown in Tables 1 and 2.

[0044]

[0045]

[0046] 100, 200, 300 Sodium bicarbonate powder manufacturing apparatus 1 Crystallization tank 2 Stirring device 3 Liquid in crystallization tank 4 Vortex turbo mixer pump 5 Circulation piping 6 Supply piping for carbon dioxide-containing gas 7 Feed piping 8 Centrifugal dehydrator 9 Filtrate 10 Sodium bicarbonate cake 11 Drying equipment 12 Sodium bicarbonate powder 13 Magnetic pump 14 YJ nozzle 15 Container 16 Liquid to be sprayed 17 Pump 18 Two-fluid nozzle 19 Hot air 20 Spray cylinder 21 Cyclone 22 Recovery container 23 Sodium bicarbonate powder 24 Filter 25 Polystyrene resin container 26 Sodium bicarbonate powder

Claims

1. Sodium bicarbonate powder with an oil absorption capacity of 40 mL / 100 g or more.

2. The sodium bicarbonate powder according to claim 1, wherein the crystallite size of the (210) plane is 75 nm or less and the crystallite size of the (121) plane is 70 nm or less.

3. The sodium bicarbonate powder according to claim 1, wherein the ratio (D210 / D121) of the crystallite size of the (210) plane (D210) to the crystallite size of the (121) plane (D121) is 0.60 to 1.

00.

4. Sodium bicarbonate powder having an apparent density of 0.32 g / mL or less.

5. Sodium bicarbonate powder according to claim 4, wherein the crystallite size of the (210) plane is 75 nm or less and the crystallite size of the (121) plane is 70 nm or less.

6. The sodium bicarbonate powder according to claim 4, wherein the ratio (D210 / D121) of the crystallite size of the (210) plane (D210) to the crystallite size of the (121) plane (D121) is 0.60 to 1.

00.

7. Sodium bicarbonate powder having an oil absorption of 40 mL / 100 g or more and an apparent density of 0.32 g / mL or less.

8. The sodium bicarbonate powder according to claim 7, wherein the crystallite size of the (210) plane is 75 nm or less and the crystallite size of the (121) plane is 70 nm or less.

9. The sodium bicarbonate powder according to claim 7, wherein the ratio (D210 / D121) of the crystallite size of the (210) plane (D210) to the crystallite size of the (121) plane (D121) is 0.60 to 1.

00.

10. The sodium bicarbonate powder according to any one of claims 1 to 9, having an oil absorption of 100 mL / 100 g or more.

11. The sodium bicarbonate powder according to any one of claims 1 to 9, having an apparent density of 0.10 g / mL or less.

12. Sodium bicarbonate powder according to any one of claims 1 to 9, having an average particle size (d50) of 12 μm to 50 μm.

13. Sodium bicarbonate powder according to any one of claims 1 to 9, wherein the crystallite size of the (210) plane is 60 nm or less or 45 nm or less, and the crystallite size of the (121) plane is 55 nm or less.

14. A method for producing sodium bicarbonate by supplying fine bubbles of gas containing carbon dioxide to an aqueous solution of sodium hydroxide or an aqueous solution of sodium carbonate to obtain sodium bicarbonate.

15. A method for producing sodium bicarbonate, in which an aqueous solution of sodium bicarbonate is sprayed using a spray dryer to obtain sodium bicarbonate.

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