JPS60231664A - Production of tablets of sodium dichloroisocyanurate showing smooth dissolution - Google Patents

Abstract

PURPOSE:Tablets of sodium dichloroisocyanurate holding free water at room temperature is heated with high-frequency dielectric heater to dry it free from water whereby tablets which smoothly dissolve in water without collapse and swelling are obtained. CONSTITUTION:Sodium dichloroisocyanurate whose free water is adjusted to 14.1-20wt% at room temperature is tabletted with a pressure of at least 35kg/ cm<2>. The tablets are dried by high-frequency dielectric heating so that the temperature of the tablets becomes higher than 50 deg.C, preferably 60-80 deg.C on their surfaces and a part of crystal water is eliminated to give the tables of sodium dichloroisocyanurate which has no free water and dissolves smoothly in water. USE:They are used as a solid chlorine agent liberating active chlorine for sterilization and disinfection of water in pool, from sewage and so on.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sodium dichloroisocyanurate tablets that exhibit smooth solubility in water without disintegration or swelling.

Sodium dichloroisocyanurate is a solid chlorine agent capable of releasing active chlorine, and is an extremely useful compound for sterilizing and disinfecting pool water, floor wastewater, sewage wastewater, etc. Sodium dichloroisocyanurate is generally used in the form of either granules or tablets, but it is often used as a tablet because it is easy to handle.

Conventionally, sodium dichloroisocyanurate has been compressed into tablets by adding water to powdered sodium dichloroisocyanurate, compressing it into tablets, and drying the tablet (Japanese Patent Publication No. 1983-23198); A method of compression molding water salt at a pressure of about 2,000 to 10,000 psi (Japanese Patent Application Laid-Open No. 50-48116 @
), a method for tableting granular sodium dichloroisocyanurate having a moisture content in the range of 7 to 11% (Japanese Patent Laid-Open No. 55-6
2011 Publication) and others.

However, when the sodium dichloroisocyanurate tablets produced by each of the above methods are placed in water or brought into contact with water, the tablets disintegrate within a very short time or are accompanied by a phenomenon of significant swelling. there were.

Therefore, when such tablets are used as a pool disinfectant, they have the advantage of being fast-acting and allowing immediate swimming, but the administered drug dissolves all at once, increasing the active chlorine concentration more than necessary and irritating the eyes of swimmers. However, the active chlorine disappears quickly, requiring frequent replenishment of chemicals, which requires a great deal of effort to maintain and manage. In addition, sodium dichloroisocyanurate tablets are filled into the cartridge in multiple stages,
When the lower opening is used in contact with legal discharge water, the water that rises due to capillary action is adsorbed by the tablets in the cartridge that are not in direct contact with the treated water, and the inside wall of the cartridge is absorbed. This method has the disadvantage that the tablets swell and become clogged in the cartridge, causing a so-called shelf-hanging phenomenon, making it impossible to supply active chlorine smoothly.

In order to prevent swelling and disintegration of such sodium dichloroisocyanurate tablets and to smoothly dissolve them, the present inventor has developed a method for tabletting sodium dichloroisocyanurate with a moisture content of 7 to 20%, and then proposed a method of heating the tablet to 50°C or higher under conditions that would prevent the moisture in the tablet from vaporizing and escaping. (Refer to Japanese Unexamined Patent Publication No. 57-31862.) However, according to this method, since the tablet is heated from the outside, if the tablet is large, it is difficult to uniformly heat the inside, so the treatment conditions are especially harsh on the surface. This resulted in cracks and shape changes, and the need for heating under humidified conditions meant that it was not necessarily suitable for mass production.

In view of these circumstances, the present inventor has repeatedly conducted various tests, and as a result, the present inventors have found that a tablet molded product of sodium dichloroisocyanurate, which contains free water at room temperature, can be dried to a state in which it does not contain free water at room temperature by high-frequency dielectric heating. The present invention was completed based on the finding that sodium dichloroisocyanurate tablets exhibiting smooth solubility can be obtained by this method.

When carrying out the method of the present invention, the moisture content of the sodium dichloroisocyanurate tablet should be adjusted to a range of 14.1 to 20%.

When the moisture content exceeds 20%, water oozes out on the surface of the tablet.
It is extremely difficult to tablet.

In order to tablet sodium dichloroisocyanurate, a pressure of at least 350 kg/cm" should be applied; if the molding pressure is lower than this, the hardness will be low and there is a risk of "disintegration" during transportation.

When heating by high-frequency dielectric, the surface temperature of the tablet is adjusted to 50° C. or higher, preferably in the range of 60 to 80° C., and a portion of the crystal water is released.

There is no need to particularly adjust the humidity of the atmosphere during heating using high-frequency dielectric, but if you are used to processing for a long time that results in a significant drop in moisture, you may need to increase or decrease the humidity necessary to avoid this. May be added.

In addition, the method of the present invention involves compressing sodium dichloroisocyanurate, which has no free water at room temperature, into tablets and leaving the tablets in a high-temperature atmosphere or spraying water onto the tablets.
% or more of water and drying this by high-frequency dielectric heating, it is possible to produce sodium dichloroisocyanurate tablets that do not disintegrate or swell when they come into contact with water. The method of the present invention will be specifically explained below using Reference Examples and Examples.

Reference Example: 15 g of granular sodium dichloroisocyanurate with a water content of 7.9% and a water content of 14.9% were placed in a die with a diameter of 30 mm, and compressed into tablets at a pressure of approximately 1000 kg/cm'' to contain a considerable amount of water. Tablets of sodium dichloroisocyanurate were formed.

By heating these tablets, each tablet was placed on a wire mesh with a 172-inch mesh and immersed in water.The tablets with a water content of 7.9% were heated for 255 seconds, and the water content was 14.
All of the 9% tablets disintegrated in 370 seconds and fell off the wire.

Next, pour 20ml of water into a petri dish with a diameter of 100mm.
Two tablets compressed under the same conditions as above were stacked one on top of the other, and a swelling test was carried out. The tablets above one after another absorbed water and swelled, and one hour later, the tablets with a water content of 7.9% The one with a water content of 14.9% expanded to a diameter of 47 mm, and the one with a water content of 14.9% expanded to a diameter of 35 mm.

Example 1 15 g of granular sodium dichloroisocyanurate with a water content of 14.9% was placed in a die with a diameter of 30 mm, and the
After compressing into tablets at a pressure of 0 kg/cm2, the tablets were placed in a 600-home microwave oven (National N E-6).
310 model, oscillation frequency 2450 MHz), and heated until the surface temperature reached 65°C.

The water content of the sodium dichloroisocyanurate tablets treated in this way was 13.95%, and when the disintegration in water was examined in the same manner as in the reference example, none of them disintegrated and was uniformly dissolved from the surface. After 60 to 70 minutes, the mixture was completely dissolved. A swelling test similar to that of the reference example was conducted for ice crystals, and although water absorption was observed in the tablet after 48 hours, there was no change in its diameter or height, and it did not swell at all.

Example 2 15 g of granular sodium dichloroisocyanurate with a water content of 7.9% was placed in a die with a diameter of 30 mm, and the
The tablets were compressed at a pressure of 1.5 kg/cm", and while measuring the weight, atomized water was sprayed on the tablets until the moisture content reached 15.0%.
- After incubation at night, this one tablet was heated in the same manner as in Example 1.

The water content of the sodium dichloroisocyanurate tablet thus obtained was 14.1%, and its disintegration in water was examined in the same manner as in the above-mentioned Reference Examples and Examples.
All of them dissolve uniformly from the surface without disintegrating, and 6
Completely dissolved after 0 to 70 minutes.

Next, a swelling test was conducted, and although water absorption was observed in the tablets after 48 hours, there was no change in the diameter or height and no swelling occurred at all.

Claims (1)

[Claims] il+ Dichloroisocyanuric acid exhibiting smooth solubility characterized by high-frequency dielectric heating of a tablet molded product of sodium dichloroisocyanurate that has free water at room temperature to a state that does not have free water at room temperature. Method for manufacturing sodium tablets. (2) The manufacturing method according to claim (1), which comprises a step of tabletting sodium dichloroisocyanurate containing free water and a step of subjecting it to high-frequency dielectric heating. (3) A claim consisting of the step of adding water to a compressed sodium dichloroisocyanurate tablet to produce a compressed tablet of sodium dichloroisocyanurate containing free water, and the step of heating the same with high frequency dielectric heating. The manufacturing method described in (1).