JP2016216447A - Manufacturing method of anhydrous sodium acetate crystal and anhydrous sodium acetate crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently provide anhydrous sodium acetate crystals having a large bulk density. SOLUTION: In producing anhydrous sodium acetate crystal having a bulk density of 0.75 g / mL or more, anhydrous sodium acetate having a volatile content of 2.0% by weight or more and a bulk density of less than 0.75 g / mL and a solvent are used. A method for producing anhydrous sodium acetate crystals, which comprises drying the mixture at 50 to 140 ° C. to a volatile content of less than 2.0% by weight. [Selection diagram] None

Description

  The present invention relates to a method for producing anhydrous sodium acetate crystals, and more particularly to a method for producing anhydrous sodium acetate crystals having a large bulk density and an anhydrous sodium acetate crystal having a large bulk density.

  In general, anhydrous sodium acetate is a food additive such as shelf life improver, acidulant, pH adjuster, and a useful compound as a reagent. In recent years, it has been used for pharmaceutical applications such as hemodialysate powder formulations. It has increased.

  Among the above-mentioned applications, in particular, in use for food additives, it is common to use a mixture of a plurality of organic acids and organic salts depending on the purpose, and in such a method of use, In many cases, the proportion of anhydrous sodium acetate after mixing is large. Therefore, anhydrous sodium acetate has a large influence on the total volume after mixing, and anhydrous sodium acetate having a large bulk density is desired so that the volume of the mixed product can be reduced.

  In general, as a method for producing anhydrous sodium acetate crystals, a sodium compound such as sodium hydroxide or sodium carbonate is reacted with acetic acid to form sodium acetate trihydrate, which is dehydrated at 120 ° C. or higher. Thus, a method for producing anhydrous sodium acetate crystals is known.

  In addition to the above production method, as a method for producing anhydrous sodium acetate crystals, a method of dehydrating an aqueous sodium acetate solution under a reduced pressure of 200 mmHg or less (for example, see Patent Document 1), or spray drying an aqueous sodium acetate solution. A method (see, for example, Patent Document 2) is also known.

JP 05-320090 A JP-A-55-007236

In the method described in the patent document or the like, usually, crystals having a low bulk density, for example, anhydrous sodium acetate crystals of about 0.70 g / mL, are obtained. 1) A method of pulverizing anhydrous sodium acetate particles to make the particles smaller, and (2) a method of compressing the particles can be considered.
However, in anhydrous sodium acetate, the above methods (1) and (2) cannot sufficiently increase the bulk density, and are difficult to apply to, for example, food additives.

  Therefore, an object of the present invention is to efficiently provide anhydrous sodium acetate crystals having a large bulk density under such a background.

  However, as a result of intensive studies in view of such circumstances, the present inventors have increased the bulk density satisfactorily by drying at a specific temperature after preparing a mixture of anhydrous sodium acetate and a solvent having a specific volatile fraction. The present invention has been completed.

  That is, the gist of the present invention is that when producing anhydrous sodium acetate crystals having a bulk density of 0.75 g / mL or more, acetic anhydride having a volatile fraction of 2.0% by weight or more and a bulk density of less than 0.75 g / mL. The present invention relates to a method for producing anhydrous sodium acetate crystals by drying a mixture of sodium and a solvent at 50 to 140 ° C. to a volatile content of less than 2.0% by weight.

  In the present invention, when drying the above-mentioned mixture of anhydrous sodium acetate and solvent, by heating, a part of the surface of the crystal is dissolved, and after that, it is changed to a crystal shape that can be easily filled while stirring at the stage of drying. It is presumed that this increases the bulk density.

  In the present invention, an anhydrous sodium acetate crystal having a bulk density of 0.80 g / mL or more is also provided.

  According to the production method of the present invention, anhydrous sodium acetate crystals having a large bulk density can be obtained, and food additives such as shelf life improvers, acidulants, pH adjusters, and pharmaceuticals such as powder formulations of reagents and hemodialysis fluids. It is a compound useful as a use, and is particularly expected to be used for food additives.

The present invention is described in detail below.
The present invention is a method for obtaining anhydrous sodium acetate crystals having a bulk density of 0.75 g / mL or more from a mixture of anhydrous sodium acetate crystals having a bulk density of less than 0.75 g / mL and a solvent.

  In the present invention, the bulk density is measured with an apparent bulk density measuring device as shown in JIS K 6891. For example, using a bulk density measuring device (Kurachi Scientific Instruments), The powder can be dropped into the container from above, the overflowing powder can be scraped off, and the bulk density can be calculated from the weight of the contents.

  In the present invention, anhydrous sodium acetate crystals are produced, for example, as follows. For example, (1) a method obtained by concentrating a sodium acetate solution (for example, an aqueous solution of sodium acetate) by performing operations such as heating and decompression, crystallizing anhydrous sodium acetate crystals, and shaking off the solvent, (2 ) A method of evaporating a solvent such as water by heating a sodium acetate hydrate powder such as sodium acetate / trihydrate to a melting point or higher. In particular, (1) is preferable from the viewpoint of a short process of obtaining anhydrous sodium acetate crystals.

  In a method obtained by crystallization of anhydrous sodium acetate from a sodium acetate solution and shaking off the solvent, the operation may be performed continuously, and a mixture of anhydrous sodium acetate and a solvent (for example, water) obtained by this production method In general, the bulk density, average particle diameter, volatile fraction, etc. have a certain range.

  In the present invention, the anhydrous sodium acetate crystals obtained above and a solvent are mixed, and the volatile fraction is 2.0% by weight or more, preferably 2.3 to 20% by weight, more preferably 2.5 to 10%. It is adjusted to be 0% by weight, particularly preferably 2.8 to 6.0% by weight. If the volatile content is too low, it will be insufficient to dissolve a part of the crystals during heating, making it difficult to increase the bulk density.

  In addition, the measurement of a volatile matter is measured by calculating | requiring loss on drying, For example, the amount of volatile matter in about 0.5g of samples is measured using a heating type moisture meter MF-50 (made by A & D Co., Ltd.), The volatile content rate can be calculated from the volatile content.

In mixing with a solvent, it may be adjusted during the production of the anhydrous sodium acetate, or the volatile fraction may be adjusted by adding a solvent.
Such a solvent may be any solvent that dissolves sodium acetate, and from the viewpoint of use as a food additive, for example, aqueous solvents such as water, alcohols having 1 to 5 carbon atoms, and acetic acid are preferable. Water is preferable in terms of the temperature at which dissolution starts.

  Specific methods for preparing a mixture of anhydrous sodium acetate and solvent include a method obtained by mixing anhydrous sodium acetate crystals and a solvent, a method obtained by mixing anhydrous sodium acetate crystals, sodium acetate trihydrate and a solvent, acetic acid Examples thereof include a method obtained by drying a mixture of sodium trihydrate and a solvent. In particular, a method of mixing anhydrous sodium acetate crystals and a solvent is preferable from the viewpoint of easy adjustment of the volatile fraction.

  As described above, a mixture of anhydrous sodium acetate and a solvent is obtained. The bulk density of the mixture of anhydrous sodium acetate and a solvent is less than 0.75 g / mL, preferably 0.4 to 0. 0.74 g / mL, more preferably 0.5 to 0.73 g / mL, and particularly preferably 0.55 to 0.72 g / mL. If the initial bulk density is too small, the change in particle shape is small during the treatment for increasing the bulk density, and the bulk density tends not to increase sufficiently.

  In the present invention, a mixture of anhydrous sodium acetate and a solvent whose volatile fraction is adjusted, the volatile fraction is less than 2.0% by weight, preferably 1.5% by weight or less, more preferably 1.2% by weight or less. Dry until. If the volatile content is too high, the crystals are fused with each other, voids are increased, and crystals with low bulk density tend to be formed.

  In addition, the drying in this invention means performing operations, such as a heating, and volatilizing the solvent in solid.

  In such drying, drying is usually performed by heating, but the drying temperature is from 50 to 140 ° C., more preferably from 55 to 110 ° C., because the purpose is to dry volatile matter from a mixture of anhydrous sodium acetate and a solvent. In particular, the temperature is preferably 60 to 90 ° C. In particular, when the solvent is water, for example, the melting point of anhydrous sodium acetate trihydrate is preferably 58 ° C. or higher.

  In addition, if the drying temperature is too high, the moisture density may be drastically dried from the anhydrous sodium acetate trihydrate present in a part of the mixture of anhydrous sodium acetate and water, and voids may be generated. If the drying temperature is too low, anhydrous sodium acetate has a hygroscopic property and may not be sufficiently dried.

  In the present invention, when drying, it is also useful to introduce a gas such as air, nitrogen or argon into the system in order to adjust the evaporation temperature or speed, for example. The method of introducing into the space part of an apparatus, the method of introducing from a shaft part as seal gas, etc. are mentioned.

  As the flow rate of the gas to be introduced, for the purpose of adjusting the drying rate, if the introduction amount is large, the drying may proceed rapidly. In the case of air, it is usually 20 L / min · kg or less, particularly 1 ˜16 L / min · kg is preferable, 2 to 13 L / min · kg is more preferable, and 3 to 10 L / min · kg is particularly preferable.

  Further, the drying time may be any condition as long as the volatile content becomes less than 2.0% by weight by performing such a drying operation, and rapid drying does not occur, and is usually 30 minutes or more, preferably 30. ˜250 minutes, particularly preferably 40 to 200 minutes. If the time is too short, the evaporation rate becomes high and the crystal has many voids, so the bulk density tends to be low. If the time is too long, the shape of the crystal does not change and the bulk density tends not to change.

  Furthermore, in the present invention, when mixing and stirring and drying, for example, a high speed mixer (manufactured by Earth Technica), a vertical granulator (manufactured by Paulek), a Redige mixer (manufactured by Matsubo), a proshear mixer (Pacific Ocean) Kiko Co., Ltd.), Gehrigke Mixer (Meiji Kikai Co., Ltd.), VMT Mixer (Amixon Co., Ltd.), Paddle Dryer (Nara Machinery Co., Ltd.), Hibis Disper Mix (Primix Co., Ltd.) can be used. Among them, a high speed mixer (manufactured by Earth Technica), a paddle dryer (manufactured by Nara Machinery Co., Ltd.), and a hibis disper mix (manufactured by Primics) are preferred in terms of mixing properties.

  In the present invention, for example, when producing with a high speed mixer manufactured by Earth Technica, the stirring speed of the main wing (agitator) is preferably 8 m / s or less, particularly 0.5 to 6.0 m when stirring. / s is preferable, and further 1 to 5 m / s is preferable. If the stirring speed of the main wing is too high, pulverization occurs and the average particle size tends to decrease. Further, the stirring speed of the sub blade (disper) is preferably 8.0 m / s or less, particularly preferably 0.2 to 6.0 m / s, more preferably 0.5 to 5.0 m / s, and too fast. Crushing occurs and the average particle size tends to decrease.

  For example, in the case of producing with a paddle dryer manufactured by Nara Machinery Co., Ltd., the stirring speed of the main wing (paddle wing) is preferably 1.0 m / s or less, particularly 0.1 to 0.5 m / s when stirring. s is preferable, and further 0.15 to 0.4 m / s is preferable. If the stirring speed is too high, pulverization occurs and the average particle size tends to decrease.

  Furthermore, for example, in the case of producing with a Hibis Disper mix manufactured by Primex, the stirring speed of the main wing (planetary) is preferably 1.0 m / s or less, particularly 0.1 to 0.5 m when stirring. / S is preferable, and further 0.15 to 0.4 m / s is preferable. If the stirring speed is too high, pulverization occurs and the average particle size tends to decrease. The secondary wing (disper) may be used as long as the particles are not crushed as a crushing application when the particles are aggregated.

  In the apparatus in the above example, the stirring speed is different because the optimum stirring speed is different in order to mix the powder uniformly in each apparatus, and the mixing speed is uniform and no pulverization occurs. If it is.

  Thus, in the present invention, anhydrous sodium acetate crystals having a large bulk density can be obtained. The bulk density is 0.75 g / mL or more, preferably 0.78 g / mL or more, and particularly preferably. Is 0.80 g / mL or more, more preferably 0.82 g / mL or more, and particularly preferably 0.85 g / mL or more. When used for foods, if the bulk density is too small, the amount of anhydrous sodium acetate crystals added to the product is increased or mixing with other components becomes insufficient, and classification is performed after mixing.

  Moreover, it is preferable that the average particle diameter of the anhydrous sodium acetate crystal | crystallization obtained in this invention is 100-500 micrometers, It is especially preferable that it is 150-450 micrometers, Furthermore, it is 200-400 micrometers. If the average particle size is too small, fine powder will fly and workability will tend to be reduced. If it is too large, mixability with other components will tend to be reduced.

  The average particle size is 200 mm in diameter, using a sieve having a mesh size of 1000 μm, 500 μm, 355 μm, 255 μm, 150 μm, 106 μm, and 75 μm, and 100 g of a sample is shaken for 18 minutes with a “DA type sieve shaker” manufactured by CMT. It is a value calculated using classification and the obtained particle size data.

  Thus, the anhydrous sodium acetate crystal of the present invention having a large bulk density can be obtained, and the anhydrous sodium acetate crystal is a compound useful for pharmaceutical use such as a powder preparation of hemodialysis solution and a reagent, and particularly has a long life. It is highly expected to be used for food additives such as improvers, acidulants and pH adjusters.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “%” means a weight basis.
The volatile fraction, bulk density, and average particle size were measured as follows.

(Volatile content)
Using a heating-type moisture meter (heat-drying type moisture meter MF-50 (manufactured by A & D Co.)), the amount of volatile content in about 0.5 g of the sample is measured, and the amount of volatile content is the initial weight. The volatile fraction (%) was calculated by dividing.

(The bulk density)
Using a bulk density measuring device (Kuramo Scientific Instruments Co., Ltd.), the powder was dropped into a 100 mL container from above, the overflowed powder was scraped off, and the bulk density (g / mL) was calculated from the weight of the contents.

(Average particle size)
Using a sieve with a diameter of 200 mm, an opening size of 1000 μm, 500 μm, 355 μm, 255 μm, 150 μm, 106 μm, and 75 μm, 100 μg of the sample was shaken for 18 minutes with a CMT “DA-type sieve shaker” and classified on each sieve. Particle size data describing the cumulative distribution was created from the mass of the remaining sample, and the particle size at which the cumulative frequency was 50% was defined as the average particle size (μm).

<Production Example 1>
A 350 mm diameter DP crystallizer (manufactured by Tsukishima Kikai Co., Ltd.) is charged with a sodium acetate aqueous solution with a concentration of 57% heated to 70 ° C., stirred at a peripheral speed of 4.5 m / s, the can internal temperature is 80 ° C., and the internal pressure is 24 kPa. Concentration was carried out by adjusting the temperature and pressure so that When the sodium acetate concentration in the can reached around 66%, seed crystals were added to crystallize the crystals. Thereafter, a sodium acetate aqueous solution having a concentration of 57% is continuously charged so that the slurry concentration becomes 30% for a residence time of about 3 hours, the slurry containing crystallized anhydrous sodium acetate is extracted, and the extracted slurry is centrifuged with a centrifuge. The mixture was separated into crystals and mother liquor to obtain a mixture of anhydrous sodium acetate and water (volatile matter ratio 1.0 to 6.0%, bulk density 0.50 to 0.70 g / mL, average particle size 200 to 450 μm).

<Production Example 2>
A 250 mm diameter DP crystallizer (manufactured by Tsukishima Kikai Co., Ltd.) was charged with a 57% sodium acetate aqueous solution heated to 70 ° C., stirred at a peripheral speed of 4.5 m / s, the can internal temperature was 80 ° C., and the can internal pressure was 24 kPa. The crystal was crystallized by adjusting the temperature and pressure so as to be concentrated. Thereafter, a sodium acetate aqueous solution with a concentration of 57% is continuously added so that the slurry concentration is about 15% for a residence time of about 2 hours, a slurry containing crystallized anhydrous sodium acetate is extracted, and the extracted slurry is centrifuged with a centrifuge. The mixture was separated into crystals and mother liquor to obtain a mixture of anhydrous sodium acetate and water (volatile matter ratio 1.0 to 6.0%, bulk density 0.50 to 0.70 g / mL, average particle size 250 to 500 μm).

<Production Example 3>
The same procedure as in Production Example 2 was repeated except that about 2 kg of a slurry solution of 8% anhydrous sodium acetate crystals having an average particle diameter of 100 μm and a peripheral speed of 5.7 m / s, a residence time of 4.5 hours, and intermittently charged every 30 minutes. Thus, a mixture of anhydrous sodium acetate and water (volatile fraction: 1.0 to 6.0%, bulk density: 0.50 to 0.73 g / mL, average particle size: 200 to 450 μm) was obtained.

<Production Example 4>
In Production Example 2, a mixture of anhydrous sodium acetate and water (volatile content ratio of 1.0 to 6.0%, bulk density) except that the peripheral speed was 5.7 m / s and the residence time was 3 hours. 0.50 to 0.70 g / mL, and an average particle size of 200 to 450 μm).

<Production Example 5>
In Production Example 2, a mixture of anhydrous sodium acetate and water (with a volatile fraction of 1.0 is used) except that the peripheral speed is 3.9 m / s, the residence time is 1.5 hours, and the slurry concentration is 30% To 6.0%, a bulk density of 0.50 to 0.70 g / mL, and an average particle size of 400 to 700 μm).

(Example 1)
From Production Example 1, a mixture of anhydrous sodium acetate and water (a volatile content of 3.2%, a bulk density of 0.63 g / mL, and an average particle size of 331 μm) was obtained. 5 kg of the obtained mixture of anhydrous sodium acetate and water was put into a stirring drier and dried under the following conditions. Finally, the volatile fraction was 0.6%, the bulk density was 0.84 g / mL, and the average particle size was 274 μm. As a stirring dryer, a high speed mixer “FSGS25J” (manufactured by Earth Technica) was used.

<Conditions>
Main wing (agitator) stirring speed: peripheral speed 4.0 m / s
Secondary blade (chopper) stirring speed: peripheral speed 4.2 m / s
Heating temperature: 70 ° C
Gas flow rate: 10L / min · kg
Drying time: 40 minutes

(Example 2)
From Production Example 1, a mixture of anhydrous sodium acetate and water (volatile matter rate 2.9%, bulk density 0.62 g / mL, average particle size 323 μm) was obtained. The mixture of anhydrous sodium acetate and water obtained above was put into a stirrer, and the main blade (agitator) stirrer speed was changed from the conditions of Example 1 to a peripheral speed of 2.0 m / s and a drying time of 50 minutes. Except that, drying was performed under the same conditions as in Example 1. Finally, the volatile fraction was 0.4%, the bulk density was 0.83 g / mL, and the average particle size was 266 μm.

(Example 3)
From Production Example 2, a mixture of anhydrous sodium acetate and water (volatile fraction: 5.2%, bulk density: 0.53 g / mL, average particle size: 425 μm) was obtained. 0.5 kg of the obtained mixture of anhydrous sodium acetate and water was put into a stirrer and dried under the following conditions. Finally, the volatile fraction was 0.6%, the bulk density was 0.78 g / mL, and the average particle size was 250 μm. As the agitation dryer, a high speed mixer “LFS-2” (manufactured by Earth Technica) was used.

<Conditions>
Main wing (agitator) stirring speed: peripheral speed 1.4m / s
Secondary blade (chopper) stirring speed: peripheral speed 0.9m / s
Heating temperature: 70 ° C
Gas flow rate: 18L / min · kg
Drying time: 190 minutes

Example 4
From Production Example 3, a mixture of anhydrous sodium acetate and water (volatile matter rate 3.0%, bulk density 0.70 g / mL, average particle size 399 μm) was obtained. The obtained mixture of anhydrous sodium acetate and water was put into a stirring dryer, and further from the conditions of Example 1, except that the main wing stirring speed was changed to 2.0 m / s and the drying time was changed to 60 minutes. Drying was performed under the same conditions. Finally, the volatile fraction was 0.5%, the bulk density was 0.82 g / mL, and the average particle size was 311 μm.

(Example 5)
From Production Example 4, a mixture of anhydrous sodium acetate and water (a volatile content of 3.3%, a bulk density of 0.62 g / mL, and an average particle size of 436 μm) was obtained. 6.8 kg of the obtained mixture of anhydrous sodium acetate and water was put into a stirrer and dried under the following conditions. Finally, the volatile fraction was 0.6%, the bulk density was 0.81 g / mL, and the average particle size was 361 μm. A paddle dryer NPD-1.6W-12L (manufactured by Nara Machinery Co., Ltd.) was used as a stirring dryer.

<Conditions>
Main wing stirring speed (paddle blade): peripheral speed 0.3 m / s
Heating temperature: 70 ° C
Gas flow rate: 9L / min · kg
Drying time: 30 minutes

(Example 6)
From Production Example 4, a mixture of anhydrous sodium acetate and water (volatile fraction 3.5%, bulk density 0.61 g / mL, average particle size 436 μm) was obtained. The obtained mixture of anhydrous sodium acetate and water was put into a stirrer and dried under the same conditions as in Example 5 except that the heating temperature was changed to 65 ° C. and the drying time was changed to 40 minutes. went. Finally, the volatile fraction was 0.6%, the bulk density was 0.79 g / mL, and the average particle size was 289 μm.

(Example 7)
From Production Example 4, a mixture of anhydrous sodium acetate and water (a volatile content of 3.4%, a bulk density of 0.62 g / mL, and an average particle size of 436 μm) was obtained. The obtained mixture of anhydrous sodium acetate and water was put into a stirrer and dried under the same conditions as in Example 5 except that the heating temperature was changed to 60 ° C. and the drying time was changed to 60 minutes from the conditions in Example 5. went. Finally, the volatile fraction was 0.3%, the bulk density was 0.77 g / mL, and the average particle size was 376 μm.

(Example 8)
From Production Example 5, a mixture of anhydrous sodium acetate and water (volatile matter ratio: 4.3%, bulk density: 0.56 g / mL, average particle size: 629 μm) was obtained. The obtained mixture of anhydrous sodium acetate and solvent (water) was put into a stirring dryer, and drying was performed under the same conditions as in Example 5 except that the drying time was changed to 40 minutes from the conditions in Example 5. Finally, the volatile fraction was 1.1%, the bulk density was 0.75 g / mL, and the average particle size was 341 μm.

Example 9
From Production Example 5, a mixture of anhydrous sodium acetate and water (a volatile content of 3.3%, a bulk density of 0.59 g / mL, and an average particle size of 614 μm) was obtained. The obtained mixture of anhydrous sodium acetate and water was put into a stirring dryer, except that the heating temperature was changed to 65 ° C., the gas flow rate was 6 L / min · kg, and the drying time was changed to 50 minutes from the conditions of Example 5. Drying was performed under the same conditions as in Example 5. Finally, the volatile fraction was 0.6%, the bulk density was 0.78 g / mL, and the average particle size was 367 μm.

(Example 10)
From Production Example 5, a mixture of anhydrous sodium acetate and water (volatile fraction: 4.4%, bulk density: 0.52 g / mL, average particle size: 638 μm) was obtained. The obtained mixture of anhydrous sodium acetate and solvent (water) was put into a stirrer and the heating temperature was changed to 65 ° C., the gas flow rate was 3 L / min · kg, and the drying time was changed to 60 minutes from the conditions in Example 5. Drying was performed under the same conditions as in Example 5 except that. Finally, the volatile fraction was 1.1%, the bulk density was 0.75 g / mL, and the average particle size was 340 μm.

(Example 11)
From Production Example 5, a mixture of anhydrous sodium acetate and water (a volatile content of 4.3%, a bulk density of 0.60 g / mL, and an average particle size of 622 μm) was obtained. 1.2 kg of a mixture of anhydrous sodium acetate and water obtained was put into a stirrer and dried under the following conditions. Finally, the volatile fraction was 0.9%, the bulk density was 0.86 g / mL, and the average particle size was 391 μm. Hibis Disper mix 3D-2 (manufactured by Primics Co., Ltd.) was used as the agitation dryer.

<Conditions>
Main wing (planetary) stirring speed: peripheral speed 0.3m / s
Heating temperature: 70 ° C
Gas flow rate: 3L / min · kg
Drying time: 125 minutes

Example 12
From Production Example 3, a mixture of anhydrous sodium acetate and water (volatile matter rate 3.0%, bulk density 0.66 g / mL, average particle size 397 μm) was obtained. The obtained mixture of anhydrous sodium acetate and water was put into a stirrer and dried under the same conditions as in Example 11 except that the heating temperature was 80 ° C. and the drying time was changed to 70 minutes from the conditions in Example 11. It was. Finally, the volatile fraction was 0.5%, the bulk density was 0.75 g / mL, and the average particle size was 282 μm.

(Comparative Example 1)
From Production Example 5, a mixture of anhydrous sodium acetate and water (volatile matter ratio 4.0%, bulk density 0.59 g / mL, average particle size 614 μm) was obtained. The obtained mixture of anhydrous sodium acetate and water was put into a stirring dryer, and the same conditions as in Example 5 were applied except that the heating temperature was changed to 150 ° C. and the gas amount was changed to 6 L / min · kg from the conditions of Example 5. Drying was performed. Finally, the volatile fraction was 0.2%, the bulk density was 0.58 g / mL, and the average particle size was 614 μm.

(Comparative Example 2)
From Production Example 1, a mixture of anhydrous sodium acetate and water (volatile matter rate 5.4%, bulk density 0.53 g / mL, average particle size 320 μm) was obtained.
The mixture of anhydrous sodium acetate and water obtained above was put into a dry compression granulator and granulated under the following conditions. Finally, there was no change in the volatile fraction, the bulk density was 0.67 g / mL, and the average particle size was 960 μm. As the dry compression granulator, a roller compactor “FT160 × 60 type” (manufactured by Freund Corporation) was used.

<Conditions>
Roll compression pressure: 0.3t / cm
Interval: 0.5mm
Heating temperature: No heating Rotation speed: 7.5rpm

(Comparative Example 3)
From Production Example 1, a mixture of anhydrous sodium acetate and water (a volatile content of 3.2%, a bulk density of 0.63 g / mL, and an average particle size of 311 μm) was obtained.
The mixture of anhydrous sodium acetate and water obtained above was dried under the following conditions. Finally, the volatile fraction was 0.4%, the bulk density was 0.58 g / mL, and the average particle size did not change. DP-32 (manufactured by Yamato Scientific Co., Ltd.) was used as the dryer.

<Conditions>
Heating temperature 150 ° C
Drying time 30 minutes

  Tables 1 to 4 show conditions and evaluation results of Examples and Comparative Examples.

  From the above evaluation results, in the examples, crystals with a large bulk density are obtained, whereas in comparative examples, the bulk density is almost the same as that before the treatment, and a crystal with a large bulk density can be obtained. could not.

  Anhydrous sodium acetate crystals obtained in the present invention can obtain anhydrous sodium acetate crystals with a large bulk density, food additives such as shelf life improvers, acidulants, pH adjusters, reagents, powders of hemodialysis solutions It is a compound useful for pharmaceutical applications such as pharmaceutical preparations, and is particularly expected to be used for food additives.

Claims (7)

In producing anhydrous sodium acetate crystals having a bulk density of 0.75 g / mL or more, a mixture of anhydrous sodium acetate and a solvent having a volatile fraction of 2.0% by weight or more and a bulk density of less than 0.75 g / mL, A method for producing anhydrous sodium acetate crystals, characterized by drying at ˜140 ° C. to a volatile content of less than 2.0% by weight. The method for producing anhydrous sodium acetate crystals according to claim 1, wherein the solvent is water. The method for producing anhydrous sodium acetate crystals according to claim 1 or 2, wherein the drying time is 30 minutes or more. The method for producing anhydrous sodium acetate crystals according to any one of claims 1 to 3, wherein a gas flow rate in drying is 20 L / min · kg or less. The anhydrous sodium acetate crystal according to any one of claims 1 to 4, wherein the bulk density is 0.78 g / mL or more. An anhydrous sodium acetate crystal having a bulk density of 0.80 g / mL or more. 7. An anhydrous sodium acetate crystal according to claim 6, wherein the average particle size is 100 to 500 [mu] m.