JPH0784410B2 - Method for producing granulated product of sodium benzoate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the invention [Industrial field of application] The present invention relates to foods such as caviar, soft drinks, soy sauce and preservatives for tobacco, antipyretics, cystitis, tonsillitis, and other pharmaceuticals. The present invention relates to a method for producing a granulated product of sodium benzoate, which is widely used in various fields as a synthetic raw material such as benzoyl peroxide, and is widely used in food, medicine, organic synthetic chemical industry and the like.

[Conventional technology]

Sodium benzoate is produced by concentrating crystallization or evaporation to dryness of a solution neutralized by adding benzoic acid to an aqueous solution of caustic soda or an aqueous solution of sodium carbonate (hereinafter referred to as neutralization reaction solution) (third part).
Edition, 66 pages, commentary on Food Additives, edited by Editorial Committee on Food Additives, Kanehara Shuppan Co., Ltd., 1974).

However, since sodium benzoate is fine needle-shaped crystals, a large amount of water is likely to be contained in the voids between the crystals, and the crystals produced by concentrated crystallization can be separated by ordinary separation or filtration methods such as centrifugation or suction filtration. Even if it is tried to separate, crystals can be obtained only as a slurry or cake with a high water content of 50 to 60%, and it is necessary to further remove excess water in order to obtain sodium benzoate crystal powder. , It is difficult to efficiently obtain sodium benzoate by a method for separating a concentrated crystallization product, such as requiring a long time for further separation or filtration (ECClarke, Can.J.Chem., 1974, 52 , 3281). ). Therefore, a method of evaporating the neutralization reaction solution to dryness is generally used as a method of obtaining crystals of sodium benzoate.

Sodium benzoate obtained in this way was dried 20
It is a fine crystal of 0 mesh (70μ) or less, and there is a problem that it may stand up during handling or cause a dust explosion (HGDorsett Jr., UNITED STATES
DEPARTMENT OF THE INTERIOR OF BUREAU OF MINES, repo
rt of investigations 7132).

[Problems to be solved by the invention]

In order to prevent the fine crystals of sodium benzoate from becoming dusty during handling or causing a dust explosion, it is necessary to make the powder of fine crystals into granules of at least 100 μ or more. The present inventors have established an excellent method for producing a granulated product of sodium benzoate in order to reduce the risk of working with sodium benzoate and solve the problem of hygiene.

(B) Configuration of the Invention [Means for Solving the Problems] It is important for the present inventors to control the water content in the sodium benzoate powder when granulating the powder crystal powder of sodium benzoate. By adopting a means of using a neutralization reaction solution obtained from benzoic acid and a caustic soda aqueous solution or a sodium carbonate aqueous solution as the means, an appropriate particle size can be easily obtained, and the crystal powder of sodium benzoate can be easily granulated. It was possible to solve the above problems of dust explosion and dusting.

That is, the present invention is a sodium benzoate crystal powder obtained from a neutralization reaction solution of an aqueous solution of caustic soda or an aqueous solution of sodium carbonate and benzoic acid, the neutralization reaction solution to 100 parts by weight of sodium benzoate, water is 25 ~. The present invention relates to a method for producing a granulated product of sodium benzoate, which comprises adding 42 parts by weight to adjust the humidity and granulate.

As the benzoic acid used in the present invention, a generally used benzoic acid obtained by an oxidation reaction of toluene or the like can be used.

Further, as the caustic soda aqueous solution, a caustic soda aqueous solution obtained by electrolysis of ordinary sodium chloride can be used. Sodium carbonate having a purity widely used on an industrial scale can also be used.

The neutralization reaction is carried out so that the amount of caustic soda or sodium carbonate and benzoic acid is generally in a chemical equivalent ratio, and the caustic soda aqueous solution or sodium carbonate aqueous solution is adjusted to a concentration such that sodium benzoate does not precipitate as crystals. Using. Since the solubility of sodium benzoate in water is about 38% by weight from room temperature to around 60 ° C., when using an aqueous caustic soda solution, it is desirable to use an aqueous caustic soda solution of 15% by weight or less. The solubility of benzoic acid in water is 3g / at 20 ° C, 6g / at 40 ° C, 12g / at 60 ° C,
Since the temperature rises to 28 g / at 80 ° C, it is desirable to preheat the caustic soda aqueous solution to 40-60 ° C and add benzoic acid to promote the reaction.

The neutralization reaction liquid thus obtained is used as a raw material for obtaining a sodium benzoate crystal powder to be treated in the granulation step, and as a humidity control used for adjusting the water content in the granulation step. Divided for. As a method of using the neutralization reaction liquid, one batch may be appropriately divided into two types, one for raw material and one for humidity control, or it may be divided into two types for raw material and humidity control for each batch. It may be used and is not particularly limited.

As described above, the powder of sodium benzoate crystals is generally
It can be obtained by evaporating the obtained neutralization reaction liquid to dryness. As a method of evaporating to dryness, for example, a usual vacuum concentration method, a spray drying method, a drum drying method and the like are used. The water content in the sodium benzoate crystal obtained by the usual concentrated evaporation method is about 1%.

In the present invention, the neutralization reaction liquid is added to the crystals obtained by evaporating the neutralization reaction liquid to dryness, concentration, and the like to be used as the raw material for granulation. The neutralization reaction liquid is benzoin in the raw material for granulation. With respect to 100 parts by weight of acid soda, preferably 25 to 42 parts by weight of water,
Further, 30 to 40 parts by weight is added. For example, 30% by weight
In the case of the sodium benzoate neutralization reaction solution of 40-73 parts by weight,
More preferably, 49 to 69 parts by weight are added.

If the amount of water is less than 25 parts by weight, the mutual binding of the sodium benzoate powder particles with water is insufficient, and the amount of ungranulated products in the granulation process increases. The fact that there are many ungranulated products means that many things must be recirculated from the granulation process to the mixing or kneading process, and the granulation equipment for mixing or kneading becomes large, or There is a problem that it takes a long time for kneading.

Further, when the amount of water is more than 42 parts by weight, the amount of the crystal powder adhered to the inner wall of the mixing or kneading equipment and the granulation equipment during granulation is large, and the mutual adhesion of the obtained granulated product becomes severe,
Granulation becomes practically difficult.

As a method for mixing or kneading the sodium benzoate crystal powder and the neutralization reaction liquid, a general mixing method or a kneading method can be adopted and there is no particular limitation. The sodium benzoate crystal powder and the neutralization reaction solution may be added in any order, and the neutralization reaction solution may be added to the sodium benzoate crystal powder or vice versa.

As the mixing or kneading method, any of a container rotating type or a container fixed type mixing or kneading apparatus can be used as the equipment.
In general, a neutralization reaction solution is added to sodium benzoate crystal powder and mixed with a ribbon mixer.

After mixing or kneading the sodium benzoate crystal powder and the neutralization reaction solution, the mixture or the kneaded product is granulated by a granulator,
As the granulator, any of a rolling type, a vibration type, a compression type and an extrusion type can be used. Among these general granulation molding methods, depending on the desired granulated product quality,
A method of extruding and granulating is desirable. At this time,
The size of the granulated product is adjusted by the roughness of the perforated plate of the extruder, and is obtained as a round bar-shaped product having a diameter of 0.2 to 1.2 mm and a length of several mm to several cm.

If desired, the granulated sodium benzoate is dried to have a water content of 1% by weight or less. As the drying method used here, any of a basket type, an air flow method, a fluidizing method, a batch type and a continuous type can be applied, but in general, a continuous type fluidizing drying method is used. The dried sodium benzoate granulation product is stored in a container or the like after adjusting the particle size with a sieve. When storing, soda benzoate has hygroscopicity, so store it paying attention to moisture. Similarly, when storing and storing the same, it is desirable that the storage and storage should be performed while paying attention to moisture.

[Action]

The crystals obtained by concentrating the benzoic acid and caustic soda aqueous solution were dried at 105 ° C. and subjected to differential thermal analysis. As a result, no water of crystallization was observed and all the water was attached water. The water adhering to the surface of these crystals acts as a binding agent for the crystals, and the water to be contained in the sodium benzoate crystal powder at the time of granulation is betted with the water in the neutralization reaction solution to produce the water as described above. It exhibits an excellent effect that the grains can be formed stably and satisfactorily.

〔Example〕

 Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 100 parts by weight of a 10 wt% caustic soda aqueous solution was heated to 50 ° C., 30.5 parts by weight of benzoic acid was added with stirring for 2 hours, and the mixture was further stirred for 1 hour to obtain an aqueous sodium benzoate solution of PH9. 100 parts by weight of this aqueous solution was evaporated to dryness to obtain 27.4 parts by weight of sodium benzoate crystals having a water content of 1%. 11.4 parts by weight of the above neutralization reaction solution was added to the obtained sodium benzoate crystals, and the mixture was kneaded with a kneader for 1 hour to obtain a kneaded product of sodium benzoate for granulation.
After granulating with a horizontal extrusion granulator with m
It was dried with a hot air dryer at ℃ to obtain 28.8 parts by weight of a granulated product of sodium benzoate having a water content of 0.5%. The obtained sodium benzoate granulated product had an average hardness of 13 as a result of measuring the hardness with an A type hardness meter.
It was a granulated product with a smooth surface and no mutual adhesion, and was a round bar product with a diameter of 0.8 mm and a length of several mm to several cm. In addition, we examined the dust explosiveness with the special type dust explosion tester KPK-II type, but no dust explosion occurred even at a concentration of 2000 mg /.

Example 2 In Example 1, a 13.3 wt% sodium carbonate aqueous solution was used instead of the 10 wt% caustic soda aqueous solution.
28.2 parts by weight of a sodium benzoate granulated product having a hardness of 12 by an A type hardness meter and having no dust explosive property even at a concentration of 2000 mg / was obtained.

(C) Effect of the Invention According to the present invention, it is possible to efficiently granulate sodium benzoate crystal powder, solve the problems of dusting and dust explosiveness that fine crystals have, and handle sodium soda benzoate. The working environment and safety can be greatly improved, and the present invention makes it possible to economically produce a sodium benzoate granulated product, and contributes to the food, pharmaceutical and organic synthetic chemistry industries using the sodium benzoate. It is a thing.

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Claims (1)

[Claims] 1. A sodium benzoate crystal powder obtained from a neutralization reaction solution of an aqueous solution of caustic soda or an aqueous solution of sodium carbonate and benzoic acid is added to the neutralization reaction solution, and water is added to 100 parts by weight of sodium benzoate. A method for producing a granulated product of sodium benzoate, which comprises granulating by adjusting the humidity by adding 25 to 42 parts by weight.