JPH0710507A - Method for granulating sodium percarbonate - Google Patents

Abstract

PURPOSE:To efficiently granulate sodium percarbonate by mixing sodium carbonate being a diluent and water for granulation with sodium percarbonate and granulating them while heating to and keeping at a specific temp. CONSTITUTION:A mixer, a granulator, a transporter and the like are heat- insulated or heated and sodium percarbonate, sodium carbonate being the diluent and water required for granulation are mixed at 36-80 deg.C. Next, the mixture is supplied to and granulated by the granulator while keeping the temp. range. Thus, the mixing and granulation are executed while keeping temp. at 36-80 deg.C, Na2CO3.7H2O or Na2CO3.10H2O does not produced by the hydration of sodium carbonate at the time of adding sodium carbonate and water into sodium percarbonate, therefore the added water is not absorbed into sodium carbonate as crystllization water. As a result, the granulation is executed by adding the absolute minimum amounts of water necessitated for granulation so that granulation is efficiently executed without evaporating and drying unnecessary water at the time of drying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for granulating sodium percarbonate.

[0002]

BACKGROUND OF THE INVENTION Sodium percarbonate is a typical oxygen-based bleaching agent as well as sodium perborate, and its bleaching effect is slightly inferior to that of chlorine-based bleaching agents, but its bleaching effect is mild and synthetic fibers and As a bleaching agent for household and business use, it has the characteristics that it does not damage the fabric of animal and plant fibers or dyed fibers, does not lose color, and has no danger due to the rapid generation of chlorine. Very useful.

Sodium percarbonate itself is not inevitable
It's a safe compound, but what if it's mixed with intangibles?
Oxygen is suddenly generated due to some influence to accelerate combustion
Sometimes. For this reason, various compounds are usually added and diluted.
However, it is said that the effective oxygen content is reduced to reduce the risk.
The method is done. Natricarbonate as a diluent
Water-soluble substances such as sodium, sodium carbonate, and sodium sulfate
Machine salts are usually used. However, these inorganic
Greater risk reduction effect among salts, and relatively inexpensive
Sodium carbonate, which is highly useful as a diluent,
Mix sodium carbonate and sodium carbonate
When granulating, try adding water to mix and granulate.
Then, the diluent sodium carbonate is hydrated and Na₂CO
₃・ 7H ₂O or Na₂CO₃・ 10H₂Called O
Formed into 1.2-1.7 per 1 kg of sodium carbonate
It absorbs as much as Kg of water. Granulate in this state
For this purpose, add an excess amount of water and granulate.
On the contrary, it is necessary to evaporate and dry a large amount of water, which is very efficient.
The disadvantage is that it is a poor granulation method. Especially low outside temperature
The decrease in efficiency was remarkable in the winter.

[0004]

[Means for Solving the Problems] The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, in the present invention, when granulating the mixture, the temperature of the mixture is constantly maintained at a temperature higher than the temperature at which sodium carbonate absorbs a large amount of water of crystallization, and by mixing and granulating, a minimum amount of water is added to granulate the mixture. As a result, it is possible to perform efficient granulation without evaporating and drying unnecessary water during drying.

Sodium carbonate is 35.1 as shown in Table 1.
The transition from monohydrate to heptahydrate occurs at ℃, and further 3
It is known that it becomes a 10-hydrate salt at 2.0 ° C or lower and absorbs a large amount of water.

[0006]

[Table 1]

When the sodium percarbonate, sodium carbonate and water mixed for granulation are cooled to below 35.1 ° C., the water content is rapidly absorbed by the sodium carbonate and the apparent water content is lowered. Therefore, for granulation, water is further added to give an apparent water content, which is usually 10 to 10.
It is 15%, but it must be adjusted to. But,
In order to prevent the temperature of the mixture of the present invention from falling below 36 ° C., the temperature of the mixture is kept above 36 ° C. by keeping or warming the mixing machine for granulation, granulating machine, transporting machine, etc. , It is preferable to prevent the sodium carbonate from hydrating to decahydrate by keeping it at 40 ° C or higher,
It has become possible to provide an efficient granulation method. Here, the temperature of the mixture is preferably 80 ° C. or lower because the sodium percarbonate contained therein is decomposed when the temperature of the mixture is raised to a high temperature of 80 ° C. or higher and the effective oxygen content is lowered.

When water for granulation is added to the mixture of sodium percarbonate and sodium carbonate, first, sodium carbonate is hydrated to Na ₂ CO ₃ .H ₂ O, at which time the heat of 30 Kcal per 1 kg of sodium carbonate is obtained. appear. This amount of heat is affected by the addition ratio of sodium carbonate, but it is possible to raise the temperature of the mixture to 35.1 ° C. or higher in the summer. However, the temperature of the starting materials is low during the low temperature period from autumn to spring, and because the outside air temperature is low, the mixture is cooled and hydration proceeds during mixing and granulation, resulting in granulation. It may be difficult and additional granulation water may be required. However, hydration of sodium carbonate is prevented by keeping the temperature of the mixer or granulator by a double jacket structure by the method of the present invention, or by heating or warming it by a method such as electric heat, hot water or steam. However, it became possible to granulate without the need to add granulating water. The system of the mixer and the granulator used in the present invention can be practiced without any limitation. As for the method of heat retention and heating and the heat medium, any method and heat medium may be used as long as the temperature of the mixture can be maintained at 36 to 70 ° C.

The sodium percarbonate used in the present invention may be obtained by any method such as a crystallization method and a fluidized bed method. Further, sodium carbonate used as a diluent is preferably in the form of powder having a small particle diameter for the purpose of granulating, but is not limited to this. Further, the additives which are usually added to improve the storage stability and bleaching performance of sodium percarbonate can also be used.

[0010]

EXAMPLES The present invention will be described below with reference to examples. Example 1 4 kg of powdered sodium percarbonate and 1 K of powdered sodium carbonate
15 g of water and 0.9 kg of water using a uniaxial stirring mixer
After mixing for a minute, the mixture was granulated using a twin-screw extrusion type granulator (Fuji Paudal Co., Ltd.). The temperature of the granulated product before drying was 41 ° C. Subsequently, the granulated product was dried using a fluidized bed dryer. The time required for drying was 12 minutes. Each device worked without any problem in all steps, and the obtained granules were successfully used as a bleaching agent.

At this time, the temperature is 10 ° C., and the temperatures of the sodium percarbonate, sodium carbonate and water used are all 10 ° C.
Met. Furthermore, the mixer and granulator used were equipped with a jacket-type heating device, and warm water of 50 ° C. was circulated in the jacket for heating.

Comparative Example 1 As in Example 1, 4 kg of powdered sodium percarbonate, 1 kg of powdered sodium carbonate and 0.9 kg of water were mixed for 15 minutes using a uniaxial stirring mixer. From the middle of mixing, the apparent water content of the mixture decreased, and it became a dry powder. The mixture was tried to be granulated using a twin-screw extrusion type granulator (Fuji Paudal Co., Ltd.), but it was difficult to extrude the mixture from the granulator. The temperature of the mixture before granulation is 28
It was ℃.

The temperature at this time was 10 ° C., and the temperatures of the sodium percarbonate, sodium carbonate and water used were all 10
It was ℃. Furthermore, the mixer and granulator used were not equipped with a heat retention device and a heating device.

Comparative Example 2 4 Kg of powdered sodium percarbonate and 1 K of powdered sodium carbonate
g and 0.9 Kg of water were mixed using a uniaxial stirring mixer. Since the apparent water content gradually decreased after the mixing was started, 1.5 kg of water was gradually added and the mixing was continued. After mixing for 15 minutes, the mixture was granulated using a twin-screw extrusion type granulator (Fuji Paudal Co., Ltd.). The temperature of the granulated product before drying was 26 ° C. Continued,
The granulated product was dried using a fluidized bed dryer. The time required for drying was 28 minutes. The obtained granulated product was successfully used as a bleaching agent. The temperature at this time was 10 ° C, and the temperatures of sodium percarbonate, sodium carbonate and water used were all 10 ° C. Furthermore, the mixer and granulator used were not equipped with a heat retention device and a heating device.

[0015]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to significantly reduce the amount of water added when granulating sodium percarbonate, and the economic effect is great.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Moto Naoyama, Inoue Yamaguchi Prefecture, Ube City 5253 Oki Ube Central Glass Co., Ltd. Ube Laboratory

Claims (1)

[Claims] 1. When sodium carbonate is added to sodium percarbonate and the mixture is granulated and dried, a mixture of sodium percarbonate, sodium carbonate and added water for granulation is kept warm or heated to 36-80. A method for granulating sodium percarbonate, which is characterized by maintaining at ℃.