JPS609010B2 - Method for manufacturing sodium dichloroisocyanurate tablets with good thermal stability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sodium dichloroisocyanurate tablets with good thermal stability.

Sodium dichloroisocyanurate is a solid chlorine agent capable of releasing active chlorine, and is an extremely useful compound for sterilizing and disinfecting pool water, urine wastewater, sewage drainage, etc. As an attempt to tablet sodium dichloroisocyanurate, Japanese Patent No. 513484 (Hakama Kosho 42-12
31 Group Publication) discloses that powdered sodium dichloroisocyanurate is kneaded with water and then compressed into tablets.

However, according to this method, the sodium dichloroisocyanurate powder in a water-containing state is highly sticky and silky, so it is extremely difficult to continuously and quantitatively feed it to a tablet press, making it difficult to use on an industrial scale. Implementation is not easy.

U.S. Patent No. 3,956,444--
According to Japanese Patent No. 48116, it is proposed to tablet sodium dichloroisocyanurate dihydrate.

Sodium dichloroisocyanurate dihydrate has attracted much attention because it is flame resistant and does not cause chain thermal decomposition.

However, sodium dichloroisocyanurate dihydrate is
Since the water content is equivalent to 14.1% by weight, it causes the same operational troubles as above, and the transition point to monohydrate is 6.
6.70, free water is produced by a small amount of heat accumulation, and tablets made from this have poor storage stability during storage or transportation, and are accompanied by the phenomenon that the tablets become separated from each other and form blocks. .

The present invention has solved these deficiencies, and its purpose is to make sodium dichloroisocyanurate tablets that are flame resistant and do not cause chain thermal decomposition. The objective is to establish a manufacturing method that satisfies the following conditions: to improve the storage stability of tablets, and to facilitate implementation on an industrial scale.
More specifically, sodium dichloroisocyanurate in a moist state is extruded through a screen having a large number of small holes to form somen-like granules, and then the somen is compressed into tablets. The shaped granules are fluidized and dried to a state where the moisture content is in the range of 7 to 11% by weight, and this is compressed between rotating rolls to form granules with a high specific gravity of 0.8/sakaki or more, and then the above-mentioned similar granules are The intended purpose is achieved by compressing something into tablets.

Sodium dichloroisocyanurate has a characteristic of containing 11% by weight or more of water, that is, sodium dichloroisocyanurate dihydrate is flame resistant and does not cause chain thermal decomposition. It is known that sodium dichloroisocyanurate, which is in fact anhydrous and has a water content of 11% or less, is in the form of a powder, granules, or granules, and is accompanied by a chain combustion reaction caused by flames.

However, it should be noted that the present inventors have found that ``sodium dichloroisocyanurate with a water content in the range of 7 to 11% by weight can be tabletted in the form of neck granules in advance to improve its flame resistance. found that tablets with
Based on this, the present invention has been completed.

In the method of the present invention, wet sodium dichloroisocyanurate recovered from the reaction system is extruded through a screen having a large number of small holes to form somen-like granules, which are then mixed with a water content of 7 to 7. It is fluidized and dried to a concentration of 11% by weight, and the granulation process can be carried out extremely smoothly by processing sodium dichloroisocyanurate in a screen extrusion granulator in a state containing free water. When this is fluidized and dried to a water content of 7 to 11% by weight, it no longer has caking properties, and the sodium dichloroisocyanurate in the hopper of the tablet machine has extremely high fluidity. As a result, raw materials can be supplied to the tablet machine very smoothly and quantitatively, and it is easy to vent the raw material voids when pressurizing the raw materials filled in the tablet machine bowl. The capping phenomenon during tableting can be completely avoided, and hard tablets can be obtained with low tableting pressure.

The product obtained by the method of the present invention has flame resistance and can reduce the quantitative variation of tablets.
In addition, since no free water is generated even under high temperatures, active chlorine loss during storage is reduced, and there is no caking phenomenon between tablets, and the effective chlorine content of sodium dichloroisocyanurate dihydrate remains at 554%. However, this can be increased to 57-60%, making packaging and handling easier.

In the present invention, it is necessary to strictly control the water content of sodium dichloroisocyanurate within the range of 7 to 11% by weight, but this point can be solved by introducing humidity-controlled hot air into the fluidized drying chamber. control can be easily carried out.

According to the method of the present invention, chemically unstable wet granulation of sodium dichloroisocyanurate is carried out using a screen extrusion granulator with a small pressure, and chemical granulation is performed prior to roll granulation or tabletting under high pressure. The work is safe because the drying process is free of stable free water, and the raw material to be tableted is made into dense granules with a bulk specific gravity of 0.8 m/m or more, free from dust with an irritating odor. A good working environment can be maintained by eliminating the occurrence. The drawings show an example of equipment suitable for implementing the present invention, in which 1 is a raw material tank with a screw feeder at the bottom, 2 is a screen extrusion granulator, 3 is a fluidized dryer, 4 is a vertical comper, and 5 is a A granulator has a pair of rotating rolls, 6 is a crushing blade, 7 is a stripe, and 8 is a tablet machine.

Note that the conditions suitable for carrying out the present invention are as follows.

The screen peacock in the screen extrusion granulator 2 is
Usually it should be in the range of 0.5 to 3.0 skin, preferably 1.5 to 2.0 skin. In the fluidized dryer 3, the drying temperature of the fluidized bed is 50 to 100°C, and the water is approximately 0.02k per 1k9 of air.
It is desirable to introduce humidity-conditioned hot air containing 9.

The rotation speed of the roll in the roll granulator 5 is 5 to 5 ratio pm.
is appropriate, and the pressure applied between the rolls is 500 to 15
It should be kept within the range of 00k9/skin.

The surface pressure in the tableting machine 8 should be at least 350k9/ or more in order to impart flame resistance to the tablet product, and a range of 350 to 750k9/ is usually appropriate. In addition, during tabletting, if necessary, a small amount of lubricant such as a metal stearate may be mixed with the granular sodium dichloroisocyanurate. Sodium dichloroisocyanurate can be prepared by neutralizing dichloroisocyanuric acid with caustic soda in the presence of water or by combining trichloroisocyanuric acid, cyanuric acid and caustic soda in the presence of water in a molar ratio of 2:1:3. What is necessary is to react in such a state, cool it, and separate the precipitated crystals.

When sodium dichloroisocyanurate in a wet state is processed in a screen extrusion granulator, its water content is reduced to 15%.
It should be in the range of ~30%.

If the water content of sodium dichloroisocyanurate is below the above range, not only will the load on the granulator increase and granulation become extremely difficult, but also pulverization will appear significantly during the fluidized drying process. On the other hand, if the moisture content exceeds the above range, the somen-shaped granules formed by the screen extrusion granulator will stick to each other and form blocks in the fluidized fluidized dryer to ensure smooth continuous operation. No. When carrying out the method of the present invention, powdery or finely granular sodium dichloroisocyanurate produced in a fluidized fluidized dryer, roll granulator, etc. is mixed with wet raw materials as necessary to reduce its water content. Reproduction can be performed by keeping it within a predetermined range.

In the practice of the present invention, the particles are compressed into a roll granulator 5 and crushed, so that the size is distributed in the range of 10 to 60 mesh, with the size of 14 to 28 mesh being the center, and the bulk specific gravity is 0.8 The product forms granular sodium dichloroisocyanurate in the range of ~1.2 m/kg and is compressed into tablets, and the high specific gravity of the product is 1.3 to 1.5.
The water content in the tablet is in the range of
Those in the 11% by weight range exhibit better solubility than others.

The present invention will be explained in detail below using specific examples.

It should be noted that the blending proportions are shown in terms of weight ratio. Example 1 Sodium dichloroisocyanurate containing 25.0% moisture stored in the raw material tank 1 was extruded into granules using a screw feeder at a rate of 200k9 per hour through a screen having a large number of small holes with a pore diameter of 1.5. Continuously supplied to machine 2
The fluidized bed area was 0.75 and the water was 0.02 kg per 9 lk of air.
Humidity-controlled hot air with a temperature of 75 to 85 oo containing water is introduced into the fluidized fluidized dryer 3, where it stays for an average of 2 ship lengths, and the moisture content is 10.
．． A granulated product of 0% sodium dichloroisocyanurate hydrate was formed.

Then, the granulated product was processed in a roll granulator 5 having a diameter of 30 mm and a length of 18 mm, crushed by a crushing blade 6, and then collected by a node 7 to obtain granules larger than 60 mesh.

The average bulk specific gravity of the granular material obtained here is 0.93 ta', and it is then fed to the tablet press 8 and subjected to a surface pressure of 500.
Tablets with an average weight of 15 kg were continuously manufactured for 1 hour under a load of 9 kg/kg, and no problems occurred during this period, and the production amount reached 1300 kg. The product obtained here had a high specific gravity of 1.45 m/kg and was flame resistant, and the weight variation of the product remained within a range of ±20%.

For comparison, powdered sodium dichloroisocyanurate with a water content of 10.0% was prepared using the tablet machine 8.
However, the raw material supply became unstable and the capping phenomenon occurred, forcing low-speed operation.
The production amount in one feeding hour operation was 940 kg, and the weight variation of the product was 5.0% soil.

Example 2 Porous refractory brick with depth 10 sails, width 20 sides, and length low
A mosquito groove is provided, and in this groove, granular sodium dichloroisocyanurate and powdered sodium dichloroisocyanurate with different water contents are placed in the groove, with a density of about 1.0 mm/kg for granular particles, and powdered sodium dichloroisocyanurate. In the case of , the fuel was filled at a rate of about 0.7 days per day, one end of which was touched with a red-hot nichrome wire, and the time required for chain thermal decomposition to begin and its propagation to proceed for 5 hours was measured.The results are as follows. It was as per 1.

Table 1 As a result, the chain thermal decomposition occurs when granular sodium dichloroisocyanurate has a water content of 10% or less, and powdered sodium dichloroisocyanurate has a water content of 11% or less.
% or less.

Example 3 In Example 1, the residence time of the raw materials in the fluidized fluidized dryer was changed to vary the moisture content and the tableting pressure was changed to 350 kg/
Pass through the sodium dichloroisocyanurate tablets of 750 k9 and 750 k9/base, re-lay the tablets on a linear nichrome wire with a length of 20 ratio and resistance of 0.80 applied to a porous refractory brick, and apply electricity to increase the resistance. Table 2 shows the results of investigating the relationship between the moisture content of tablets and the propagation of thermal decomposition by subjecting the body to red heat. It has been found that they are much more thermally stable and that those with a water content of 7.0% or more do not cause chain thermal decomposition.

Example 4 In Example 1, sodium dichloroisocyanurate tablets with different moisture content and compression pressure of 500 x 9 were made by changing the residence time of the raw materials in the fluidized fluidized dryer, and the volume was 300.
Put 20 tablets of 15 tablets into a sealed glass bottle and add 30 tablets.
Table 3 shows the results of investigating the amount of decomposed gas generated and the caking phenomenon between the tablets when stored in a constant temperature room maintained at a temperature of 0.00.

The amount of decomposed gas was measured by observing changes in the height of a saturated saline water column passed through a sealed glass bottle containing tablets.

Table 3 From these results, tablets with a water content exceeding 11% begin to noticeably generate decomposition gas during storage, and tablets with a water content of 14.1% or more that generate even a small amount of free water are particularly susceptible to rapid decomposition gas generation. It was confirmed that tablets with a water content of more than 11% exhibit a remarkable casing phenomenon.

Example 5 In Example 1, various sodium dichloroisocyanurate tablets with different water contents and tableting pressures were made by changing the residence time of the raw material in the fluidized fluidized dryer, and the tablets were prepared at a humidity of 72% and a temperature of 30°C. Table 4 shows the results of examining the solubility of the tablets by leaving them in a constant temperature room at 0.

The solubility was determined by measuring the time required for the tablets to completely disintegrate and dissolve after 15 days on a metal steel plate with a mesh size of 15 inches in 2000 mm water.

Tablets with a moisture content of more than 11% will shrink in volume if left in a humid condition, while tablets with a moisture content of less than 10% will expand in volume if left in a humid condition. It was observed that the solubility of the tablets with a water content of 13% and 6% changed significantly over time, and the tablets with a water content of 10% showed little change over time and always exhibited a constant solubility.

[Brief explanation of drawings]

The drawing shows an example of equipment suitable for carrying out the method of the present invention, in which 1 is a raw material tank, 2 is a screen extrusion granulator,
3 is a fluidized dryer, 4 is a rigid compere, 5 is a roll granulation type, 6 is a crushing blade, 7 is a knot, and 8 is a tablet press.

Claims (1)

[Claims] 1. Sodium dichloroisocyanurate in a wet state is extruded through a screen having a large number of small holes to form somen-like granules, and then the somen-like granules are heated to a water content of 7 to 11% by weight. Dichloroisocyanuric acid with good thermal stability, which is characterized by fluidizing and drying it to a state within a range of temperature range, compressing it between rotating rolls to form granules with a bulk specific gravity of 0.8 g/cm^3 or more, and then tableting the granules. Method for manufacturing sodium tablets. 2. The method according to claim 1, characterized in that the granular sodium dichloroisocyanurate is compressed into tablets, which has been fluidized and dried to a moisture content of 7 to 11% by weight using humidity-adjusted hot air.