JPS62123103A - Calcium hypochlorite tablet for water sanitation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to chlorine-containing products for water sanitation.

More particularly, the present invention relates to hydrated calcium hypochlorite tablets and their manufacture.

Calcium hypochlorite is a known source of "available chlorine" for sanitary purposes, such as disinfecting water such as swimming pools or wastewater streams. Calcium hypochlorite is added to water to retain a small amount of residual [available chlorine J], which is generally sufficient to ensure that contamination with bacteria 17 is quickly eliminated, so that the water is suitable for swimming. Safe for bathing or for discharge from septic facilities.

Anhydrous calcium hypochlorite having a Ca (OCJ!) concentration of about 70 weight percent is commercially available in granular or tablet form and is added to water to provide the desired available chlorine level.

U.S. Pat. No. 4,192,763, issued March 11, 1980 to P.W. Boujan, describes the use of calcium hypochlorite as a chloride of lime and tablet-forming A'J l agent. A method is described for making tablets by mixing zinc stearate as a compound and compressing the mixture into tablets. Tablets containing 5 to 15 percent lime chloride and less zinc stearate as a lubricant have a lower rate of dissolution in water. Anhydrous calcium hypochlorite is used since water or moisture will accelerate the rate of decomposition for mixtures containing hygroscopic lime chlorides.

A similar method for reducing the solubility of calcium hypochlorite was published in Japanese Patent Publication No. 9 published on July 9, 1980.
No. 0404-1980. A mixture of calcium chloride, calcium hydroxide, and anhydrous calcium hypochlorite is formed into tablets, and the inside contains CaC.
j! 2 is present in an amount of 3 to 4 weight percent and the weight pressure of the calcium hydroxide Cum/calcium chloride is 0.5 to 3.0.

These billions of CaC12+Ca(OH)2 are necessary to reduce the solubility of the tablet. However, the stability of these tablets is severely affected in the presence of water or moisture.

A hydrated calcium hypochlorite composition has been developed that has a moisture content of greater than 4 parts by weight and is more resistant to combustion and exothermic decomposition than anhydrous products. Tableting of calcium hypochlorite with a moisture content of more than 3 parts by weight cannot be efficiently carried out using commercially available tableting equipment because the caking nature of the punching tools causes excessive wear on the equipment. Can not.

Equipment maintenance requires regular shutdowns and it is difficult to maintain product control with respect to both tablet uniformity and appearance.

One object of the present invention is to provide tablets of hydrated calcium hypochlorite compositions that can be commercially produced while minimizing cost and equipment wear.

Another object of the present invention is to provide a method for producing hydrated calcium hypochlorite that is stable and has a long shelf life.

An additional object of the present invention is to provide hydrated calcium hypochlorite tablets with controlled active chlorine release properties for sanitizing water supplies.

These and other objects of the present invention are for water sanitation consisting essentially of hydrated calcium hypochlorite mixed with a lime compound in an amount of about 0.1 to about 3 weight percent of the hydrated calcium hypochlorite. Achieved on tablets.

The figure is a graph illustrating the effect of calcium hydroxide on the water solubility of hydrated calcium hypochlorite.

Solid hydrated calcium hypochlorite granules are about 55 to about 75
percent, preferably from about 65 to about 72 percent by weight of calcium hypochlorite, Ca (OCJ!)2
about 4 to about 10 percent, preferably about 5.5 to about 8.5 percent by weight water; and about 1 to about 3 percent by weight calcium hydroxide, inert materials normally resulting from the manufacturing process, such as sodium chloride; Contains the balance of calcium chloride and calcium carbonate. Hydrated calcium iodochlorate has a specific gravity of about 2.1 to about 2.2.

Hydrated calcium hypochlorite of the type used in the present invention is
U.S. Patent No. 3,544゜267 issued to G.R. Deitsjidara on December 1, 1970 or U.S. Patent No. 3,669 issued to G.B. Faust on June 13, 1972 , 894, by known methods.

The granules of hydrated calcium hypochlorite used in the tablets of the present invention are commonly commercially produced and have a particle size in the range of about 150 to 2.000 microns.

The lime compounds used were calcium oxide, commercially available as quicklime, calcium hydroxide, commercially available as hydrated lime, and mixtures thereof.

The hydrated calcium hypochlorite particles are mixed with particles of a lime compound to provide an amount of about 0.1 to about 3 weight percent, preferably about 0.5 to about 2 weight percent, of the hydrated calcium hypochlorite. A mixture containing a range of lime compounds is produced. More layers may be used if needed, but from a cost standpoint they do not provide a substantial increase in profit.

As mentioned above, calcium hypochlorite may contain calcium hydroxide in the process as an integral part of the composition since calcium hydroxide is one of the raw materials commonly used in calcium hypochlorite production. . However, the presence of step calcium hydroxide or lime in calcium hypochlorite makes it surprising that the beneficial testicles obtained when mixing calcium oxide or calcium hydroxide with calcium hypochlorite granules as disclosed above. I can't get 1q.

The hydrated hypochlorite granules are mixed with commercially available quicklime or hydrated lime to form a substantially homogeneous mixture. Any suitable means of mixing or combining the two components may be used.

The mixture is then tabletted using commercially available tablet machines. It has been unexpectedly found that in the manufacture of tablets, an it'/l lubricant is not necessary since the lime compound used in the mixture provides excellent lubricity. Tablets made from the mixture of the invention can be easily removed from the tablet mold. The novel tablets of the present invention have a possible chlorine content of about 65 to about 70 percent, providing a controlled dissolution rate in water that is substantially less than that of hydrated calcium hypochlorite.

The following examples provide further elucidation without the intention of being limited thereby. All percentages and parts are based on heavy bottles unless otherwise specified.

Example 1 Anhydrous calcium oxide was added to hydrated calcium hypochlorite granules in an amount of 1.5 weight percent of hydrated calcium hypochlorite. The formulation was blended in a V-type blender to form a homogeneous mixture.

A 20 ton stainless steel mold [7.6 cm (>3 inches in diameter), No. 4200] and a stamper were attached to the Wabash press and enough lfi of the hydrated calcium hypochlorite-calcium oxide mixture was added. I made 6 tablets using pressure.

The tablets (200 grams each) were removed from the press without sticking to the mold and the appearance of the tablets was excellent. No mold removal was required during the tablet molding operation.

The water flow rate is 7.5 gallons per minute and the temperature is approximately 26.7°C (8°C).
Three tablets were placed in an erosive type dissolver (0 below). The tablet was allowed to dissolve for 3.0 hours, after which time the remainder of the tablet was removed, dried for 4.0 hours, and weighed. The m of dissolved Ca (OCJ2>2 was calculated by subtracting the weight of Ca (OCj!>2) remaining after the test from the initial weight. Tablets made using calcium oxide were It was 68%.

Comparative Example A Hydrated calcium hypochlorite was made into a tablet instead of a mixture of hydrated calcium hypochlorite and calcium oxide, and a stainless steel mold was made with sodium stearate solution. II
The method of Example 1 was repeated except that it was coated as a lubricant. Considerable amount of hydrated calcium hypochlorite stuck to the mold during the molding operation. The mold was difficult to use, and each tablet had to be coated with sodium stearate after each tablet was made, otherwise the punch could not be removed.

The dissolution rate measurements were repeated using three tablets containing only calcium hypochlorite. The tablets were 42 percent of their original flfc.

Using the novel tableting composition of the present invention, the tablets dissolved 38 percent slower than the hydrated calcium hypochlorite tablets of Comparative Example A.

Examples 2-4 Granular hydrated calcium hypochlorite and calcium hydroxide (
Four homogeneous mixtures were made containing calcium hydroxide (reagent grade), Olo, 75.1.5 and 3.
An amount of 0 weight percent was added. Hydrated calcium hypochlorite had the following analytical values.

Ingredients Weight%Ca
(OCJ!>266, 5-66, 6Ca (Cj!0
3) 21.7-1.8Ca (OH)2 1.8-
2.0Ca (124,5-5,2 Ca CO31,37 Na CJ 16.2-18.2820
6°8 Each mixture was tableted at a pressure of 17,000 bonds, weighing 25.3 grams and approximately 2.54 cm (
1,00 inches) in diameter, approximately 2.37 centimeters (
Tablets were made with a height of 0.93 inches) and a surface area of 29.05 square centimeters. The tablets of each mixture were placed in an open mesh basket and immersed in a tank of water with a temperature of 32°C, and the water was slowly poured into the W&11
did. During the initial dissolution time of approximately 3 hours, the tablet
．． It was removed, dried and weighed at 5F3 and 1.0 hour time intervals. Tablets with a U fill of lime to be mixed dissolved at a rate of 0.53 grams/square centimeter surface area/hour.

Tablets with 0.75 m 1 percent Ca (OH)2 impregnation are 0.40 g/sq.
Dissolved quickly. Tablets with Ca(ON>z contents of 1.5 and 3.0 weight percent respectively
．． The dissolution rate was 32 and 0.243 grams per square centimeter per hour.

The results are illustrated in the figure.

Examples 5-7 0.5, 1.5 and 2.5 weight percent lime?
d weighing 275 grams and approx.
Tablets with a diameter of centimeters (3 inches) were made. Calcium hypochlorite granules had the following analysis values: U% heavy yang Ca (OCf)2 69.5 Ca (OH)2 1.5Ca CO32
,0 Ca(12ca 1.Q Ca (CftO3)2 ca 1.ONa C
1 cal 8.0 820 7.0 The tablet was placed in a basket and submerged in a swimming pool skimmer with a water flow rate of 35 gallons/minute. The total time for dissolving the tablet was measured and found to be:

% of lime Dissolution time (hours) 0, 5 7.5 1.5 11.5 2.5 15.0 Comparative example Same as that used in Examples 5 to 7 except that no lime was added. The method of Examples 5-7 was repeated using certain hydrated hypocalcium chlorate tablets. These tablets had a dissolution time of 6.0 hours.

[Brief explanation of drawings]

The figure shows the effect of calcium hydroxide on the water solubility of hydrated calcium hyposulfite tablets.

Claims (8)

[Claims] (1) A water sanitary tablet consisting essentially of hydrated calcium hypochlorite mixed with a lime compound in an amount from about 0.1 to about 3 percent of said hydrated calcium hypochlorite. Said tablet consisting of calcium chlorite. (2) The tablet of claim 1, wherein the lime compound is selected from the group consisting of calcium oxide, calcium hydroxide, and mixtures thereof. 3. The tablet of claim 2, wherein the hydrated calcium hypochlorite contains from about 4 to about 10 weight percent water. (4) The tablet according to claim 3, wherein the lime compound is calcium oxide. 5. The tablet of claim 3, wherein the available chlorine content is from about 55 to about 75 percent. (6) The tablet according to claim 5, wherein the lime compound is calcium hydroxide. 7. The tablet of claim 3, wherein the lime compound is present in an amount of about 0.5 to about 2.0 weight percent. (8) mixing particles of hydrated calcium hypochlorite with particles of a lime compound to form a homogeneous mixture comprising from about 0.1 to about 3 weight percent of the brine compound; and compression molding the homogeneous mixture. A method for manufacturing a tablet according to claim 1, comprising making a tablet.