JPH0688936B2 - Method for producing granular 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 granulation method of sodium benzoate, which is widely used in various fields as a synthetic raw material for benzoyl peroxide and the like, 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 liquid obtained by adding benzoic acid to an aqueous solution of caustic soda or an aqueous solution of sodium carbonate (hereinafter referred to as a neutralization reaction liquid) (third edition food additive). 66 pages of the compendial document, published by the editorial committee of the compendial document of food additives, published by Kanehara Publishing Co., Ltd. in 1974) However, since sodium benzoate is a fine needle crystal, a large amount of water is contained in the voids between the crystals. Even if an attempt is made to separate the crystals produced by the concentrated crystallization by an ordinary separation or filtration method such as centrifugation or suction filtration, the crystals are formed into a slurry or cake with a water content of 50 to 60% and a high water content. In order to obtain only sodium benzoate crystal powder, it is necessary to further remove excess water, and it takes a long time for further separation or filtration. Works with soda It is difficult to obtain good (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
It was a fine crystal of 0 mesh or less, and there was a problem that it powdered when handling and caused a dust explosion. (HG
Dorsett Jr., UNITED STATES DEPARTMENT OF THE INTERI
OR OF BUREAU OF MINES, report of investigations 713
2) [Problems to be solved by the invention] Fine crystals of sodium benzoate may become powdery during handling,
In order to prevent the dust explosion from occurring, it is necessary to make the powder consisting of fine crystals into a granule having a particle size of at least 100 μ, so the present inventors established a method for efficiently granulating sodium benzoate. However, various studies were conducted to reduce the danger of working with sodium benzoate and to solve the problem of hygiene.

(B) Configuration of the invention [Means for solving the problems] The present inventors can easily prepare a granulated sodium benzoate by adjusting the proportion of water in the sodium benzoate to an appropriate range. In addition, they have found that a sodium benzoate granulated product can be obtained economically and have solved the problems of dust explosion and dusting, resulting in the present invention.

That is, the present invention relates to a method for producing granular sodium benzoate, which comprises granulating sodium benzoate containing 20 to 30% by weight of water.

In the present invention, sodium benzoate obtained by evaporating the neutralization reaction solution to dryness or evaporation can be used. As a method for evaporating the neutralization reaction solution to dryness by evaporation or concentration, an ordinary method such as a vacuum concentration method, a spray dry method, a drum dry method or the like is used.

The water content of sodium benzoate obtained as needle-shaped crystals of 10 μm or less depends on the crystal acquisition method, but is usually less than 1% in the case of crystals obtained by evaporation to dryness.

In order to efficiently granulate the sodium benzoate obtained in this way, it is necessary to contain 20 to 30% by weight of water in the sodium benzoate, particularly when the water content is 23 to 29% by weight, Better granulation. The water contained in sodium benzoate does not necessarily have to be the water added from the outside, and the evaporation of the neutralization reaction solution caused the residual water to become suitable for granulation (20 to 30% by weight). By means such as sometimes stopping, no water is added from the outside,
It can also be used as it is as a raw material for granulation.

When the content of water is less than 20% by weight, the mutual binding of the sodium benzoate powder particles with water is insufficient, and the number of ungranulated products in the granulation process increases. The fact that there are many ungranulated products means that many things must be recycled from the granulation process to the mixing or kneading process, and the granulating equipment for mixing or kneading is enlarged, or There is a problem that it takes a long time for kneading.

Further, if the water content is more than 30% by weight, the amount of the crystal powder adhered to the inner wall of the mixing or kneading equipment and the granulation equipment at the time of granulation is large, and the mutual adhesion of the obtained granulated product is also caused. It becomes violent and practically difficult to granulate.

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

For mixing or kneading, any equipment of container rotation type or container fixed type can be used. Generally, water is added to the sodium benzoate powder obtained by evaporating the neutralization reaction solution to dryness, and mixed with a ribbon mixer.

Although sodium benzoate containing an appropriate amount of water is granulated by a granulator, any of a rolling type, a vibration type, a compression type and an extrusion type can be used as the granulating device. Among these general granulation methods, the method of granulating by extrusion molding is desirable, depending on the desired quality of the granulated product. At this time, the size of the granulated product is adjusted by the roughness of the perforated plate of the extruder to obtain 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, sodium benzoate has hygroscopic properties, 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]

An aqueous solution of sodium benzoate was obtained from an aqueous solution of benzoic acid and caustic soda or an aqueous solution of sodium carbonate, and the crystals obtained by concentrating this were dried at 105 ° C and the results of differential thermal analysis showed that no water of crystallization was observed and all the water was attached. It was water. The water adhering to the surface of these crystals acts as a binder for the mutual crystals, and in particular, a specific amount of water has an excellent effect that the granulation of sodium benzoate is stabilized and good.

〔Example〕

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

100 parts by weight of a 10 wt% caustic soda aqueous solution was heated to 50 ° C., a stoichiometric amount of benzoic acid was added to this under stirring (30.5 parts by weight), and the mixture was further stirred for 1 hour to obtain an aqueous sodium benzoate solution. This aqueous solution was concentrated and evaporated to dryness to obtain 35.3 parts by weight of needle-shaped crystalline sodium benzoate powder having a water content of 0.5% and 10 μm or less.
Water was added to the sodium benzoate powder at the ratios shown in Table 1 and mixed with a kneader to obtain a granulated mixture. The obtained mixture for granulation is granulated by a horizontal extrusion granulator having a 1.0 mm diameter plate and then dried by a hot air dryer at 110 ° C to obtain a water-containing granulated product, and its appearance is observed. did.

As shown in Examples 1 to 3, when the water content of sodium benzoate is adjusted to 20 to 30% by weight and granulated, there is almost no ungranulated product and the surface of the granulated product is smooth and large. A product with uniform liquidity and high liquidity was obtained. Most (99% by weight or more)
The granulated product of was a round bar-shaped product having a diameter of 1.0 mm and a length of several mm to several cm.

On the other hand, in Comparative Example 1 in which the water content of sodium benzoate was less than 20% by weight, there were many ungranulated products and the surface of the granulated products was rough.

Further, in Comparative Example 2 in which the water content of sodium benzoate was more than 30% by weight, the granulated products adhered to each other to form a large lump, and the granulated product surface had large irregularities and a fluidized granulated product was obtained. There wasn't.

(C) Effect of the Invention According to the method of the present invention, sodium benzoate can be efficiently granulated, and it is possible to prevent dusting and dust explosion that occur due to fine crystals, and as a result, when handling sodium benzoate. The present invention can greatly improve the working environment and safety, and the present invention contributes to the food, pharmaceutical and organic synthetic chemistry industries using sodium benzoate.

Claims (1)

[Claims] 1. A method for producing granular sodium benzoate, which comprises granulating sodium benzoate containing 20 to 30% by weight of water.