JPS5874508A - Manufacture of sodium percarbonate - Google Patents

Abstract

PURPOSE:To manufacture granules with superior solubility in water by adding specified amounts of one of silicic acid hydrosol, a silicate and hydrosol of aluminum oxide hydrate, phosphoric acid or a salt thereof, ortho- or metaboric acid or a salt thereof, and an org. multivalent carboxylic acid or a salt thereof to powdered sodium percarbonate and granulting them. CONSTITUTION:When sodium percarbonate powder is granulated, to the powder are added 0.01-0.5% as SiO2 or Al2O3 of one of silicic acid hydrosol, an alkali metallic silicate such as sodium silicate and hydrosol of aluminum oxide hydrate basing on the amount of the sodium percarbonate, 0.1-5% phosphoric acid or salt thereof such as sodium primary phosphate in the form of 5-30% aqueous soln., 0.1-0.5% ortho- or metaboric acid or salt thereof, and 0.1-0.5% org. multivalent carboxylic acid such as citric acid, succinic acid or tartaric acid or salt thereof, and they are kneaded and granulated. A granular sodium percarbonate bleaching agent with superior solubility in water and stability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing soda percarbonate, which has storage stability and dissolves very quickly in water.

Sodium percarbonate is a typical oxygen bleaching agent along with sodium perborate. Sodium perborate has low solubility at room temperature and does not exhibit sufficient bleaching effects. For this reason, in Japan, where people are not used to washing clothes with hot water, they are not used much for purposes other than business purposes. Chlorine bleach is also commonly used, but it has drawbacks such as a strong pungent odor and bleaching of dyed clothing.

It does not have the drawbacks seen in recent chlorine-based whitening agents.

Soda percarbonate, which has high solubility at low temperatures around room temperature, is becoming increasingly important.

The common method for producing soda percarbonate is to react sodium carbonate and hydrogen peroxide to obtain a sodium percarbonate crystal powder using a nine-reaction crystallization method, then perform wet granulation and drying to form a product. be.

Generally, when soda percarbonate is left in the air, it absorbs moisture and the active oxygen concentration of the sodium percarbonate decreases, so that it no longer exhibits a sufficient bleaching effect when used. For this purpose, inorganic compounds such as water glass, phosphates, silicates, magnesium salts are added to the reaction product;
T,! , ott**tb compounds, or spraying or coating the granules with the above-mentioned inorganic compounds are known. However, although the granular soda percarbonate obtained by this method has superior solubility compared to sodium borate, its solubility at room temperature is not so great and it cannot be dissolved when used in ordinary households. The problem is that it takes a lot of time to bleach, and as a result, a sufficient bleaching effect cannot be achieved.

As an attempt to improve these drawbacks of sodium percarbonate, there is a method in which granulated and dried sodium percarbonate is heated again at a temperature range of 75 to 135° C. for a specific period of time to impart rapid solubility. Although it is possible to obtain sodium percarbonate having relatively good solubility according to this method, heating for a long time at a relatively high temperature is required to obtain a product with satisfactory rapid dissolution.

However, if the treatment is carried out under such conditions, the active oxygen possessed by sodium percarbonate will be lost due to decomposition, resulting in rapid decomposition.
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As a result of various studies, the present inventors have found that water glass and silicate, which have been conventionally used as stabilizers, have been added to water glass and silicate. As a result of investigating the solubility of the above-mentioned inorganic compounds in sodium percarbonate as an aqueous solution or aqueous dispersion, it was found that when wet granulation was performed by adding the above inorganic compounds to sodium percarbonate as an aqueous solution or aqueous dispersion, the added inorganic compounds gelled and deposited into one particle during the granulation process. However,
It was discovered that the gelation rate has a very important relationship with the water solubility of the granulated and dried granulated sodium percarbonate, and also that the type and combination of additives are extremely important. Based on this finding, the present invention was completed.

An object of the present invention is to have excellent solubility in water.

K provides glazed granular soda percarbonate with stability and stability.
be.

In the present invention, when granulating powdered soda percarbonate,
Sodium percarbonate, at least one selected from hydrosyl silicate, silicate, or hydrous aluminum oxide, and at least one selected from phosphoric acid or its salt, boric acid or its salt, and organic polyhydric carboxylic acid or its salt. The present invention relates to a method for producing soda percarbonate, which comprises adding and granulating.

Hydrosyl silicate or silicate or hydrous flujnium oxide used in the present invention, phosphoric acid or its salt, ortho or meta, boric acid or its salt, organic polyhydric carboxylic acid or its salt are hereinafter referred to as additives. [Hydrosyl silicate or silicate or hydrated aluminum oxide] is the additive of the first group, ``phosphoric acid or its salt, boric acid or its salt, organic polycarboxylic acid or its salt'' are called the second group of additives.

The first group of additives used in the present invention, silicates, are:
Alkali metal salt, commercially available No. 1 to No. 3 water glass,
Potassium silicate, lithium silicate, magnesium silicate, powdered sodium silicate, and an aqueous dispersion of silicon oxide of 10 to 100 mμ in 9 grains (commercially available products include, for example, amorphous aluminum oxide). (Commercially available products include, for example, alumina sol).The hydrosyl silicate or hydrous aluminum oxide is usually used in a concentration of 1 to 30%, based on sodium percarbonate.

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It is added in a range of -5% by weight. Among the above-mentioned silicates, commercially available No. 1 to No. 3 water glasses with a concentration of 1 to 25% are used, and others such as potassium silicate, lithium silicate, and magnesium silicate.

Powdered sodium silicate is used at a concentration of 1 to 20%, and 5103 to sodium percarbonate is 0.01 to 20%.
0.5-Amount〒1. Added in range i.

The above magnesium silicate is 0.1 to 0. ! If the amount of aluminum hydrosil added is greater than the above-mentioned amount, the solubility will deteriorate and this is not preferable.9 In order to fully achieve the purpose of the present invention and exhibit remarkable effects,
It is preferable to add lzos in an amount of 0.01 to 0.3% by weight.

In the present invention, it is important that the first group of additives and the second group of additives are added at the same time during granulation. If the additives of Group 1 and the additives of Group 2 are added separately over time, the solubility will be significantly impaired, which is undesirable.The additive of Group 1 is silicate human sol.

Among hydrous aluminum oxide hydrosyl and silicates,
Lithium silicate and No. 1 to No. 3 water glass are particularly suitable.

The phosphates that are the second group of additives used in the present invention include monobasic sodium phosphate, dibasic sodium phosphate, tribasic sodium phosphate, sodium picrate, sodium metaphosphate,
Sodium tripolyphosphate.

Sodium tetrapolyphosphate, sodium hexametaphosphate, sodium decapolyphosphate, monopotassium phosphate.

Potassium diphosphate, potassium myphosphate, etc.

Particularly preferred are primary, secondary and tertiary sodium phosphate. In addition, organic polycarboxylic acids or their salts include citric acid, succinic acid, alcoholic acid, oxalic acid, chloro/acid, lactic acid,
Examples include malonic acid and malic acid, and their salts are generally sodium salts. Among these, citric acid, succinic acid,
Alcoholic acid and lactic acid are preferred, and their sodium salts are preferred for *. These second group additives in the present invention include crosstalk,
During kneading, the pH of the first group of additives is adjusted, which acts to promote gelation of the first group of additives.

In the present invention, the concentration of phosphoric acid or its salt as the second group additive is usually 5 to 50%, and the concentration of boric acid or its salt, organic polyhydric carboxylic acid or its salt is usually 1 to 50%. 10% is used, and in order to fully exhibit the effect of the second group of additives, it is usually used in a range of 0.01 to 0.5% (by weight) based on the sodium percarbonate.

In the present invention, a wet granulation method is applied to granulate sodium percarbonate, and any type of granulator used in the wet method can be used for granulation, but crosstalk and kneading may occur. A well-performing granulator is preferred. During granulation, water is added as desired to mix and knead so that the water content of the sodium percarbonate becomes 10 to 15%.

Examples of granulators used for granulation include a screw extruder mixer with a screen with a hole diameter of 0.7 to 1.5 m installed at the tip, or an extruder that the applicant previously applied for. A kneading and kneading type granulator is used.

The product obtained according to the present invention has excellent storage stability, good solubility in cold water, and foaming property when dissolved. The granular sodium percarbonate obtained according to the present invention can be incorporated into detergents and the like as an oxygen bleaching agent.

The powdered soda percarbonate used in the present invention is:

A method in which hydrogen peroxide is applied to an aqueous solution of sodium carbonate to crystallize crystals from the aqueous liquid (crystallization method), and a solution method in which a slurry is formed in an inert solvent and reacted.

Alternatively, any method such as a dry method in which an aqueous hydrogen peroxide solution is added to powdered soda carbonate can be used, but wet sodium percarbonate obtained by a crystallization method is generally preferred.

Reference Example (Production Example of Sodium Percarbonate) A reaction mother liquor 30j containing 12% of NaCO@12% is prepared using a stainless steel reactor equipped with a stirrer, a thermometer, and a cooling jacket. While maintaining the mother liquor at a temperature of 15-20°C, 60% H! 0! -2.5 o'clock m
Nag cos 5 and OK9 were simultaneously added gradually over about 1 hour, and after the addition, the slurry was stirred for another 1 hour while maintaining the above temperature. The resulting slurry was separated into sodium percarbonate crystals using a rod separator. Approximately 3.5~ of wet sodium percarbonate was obtained by removing the P solution.

Next, examples of the present invention will be shown.

The fj1 moist soda percarbonate powder obtained by the method of the reference example is fed to a kneader, and the additives of the first group and the second group of the present invention shown in the table are added to the powder at desired concentrations. A predetermined amount of each was added, and further a desired amount of water was added so that the water content became 10 to 15%, and kneaded for about 30 minutes. Next, the kneaded wet mass was granulated using a pelletizer, and the mosquito pellets were dried using a fluidized fluidized drier to obtain a product. The dissolution rate was measured for this product.

To maintain a constant dissolution rate, add 1 g of pure water at 25°C to a beaker.
A stirring bar with a stirring blade having a height of 40 u and a width of 251 m was rotated at 25 Orpm, a 5 y sample was added, and the time period for the particles to completely disappear was determined.

Talented. The obtained product say was placed in a beaker of 100111 and left for 30 days under the conditions of 35°C and 80% H, the amount of effective oxygen before and after the test was determined, and the rate of decrease in effective oxygen was determined according to the linear equation. The storage stability was measured. As a result, the effective oxygen reduction rate was 10 to 50%.

Claims (1)

[Claims] (1) When granulating powdered soda percarbonate. Sodium percarbonate, at least one selected from hydrosyl silicate or silicate, or hydrous aluminum oxide hydrosol, II boric acid or its salt, ortho- or metaboric acid or its salt, and an organic polyhydric carbonate. Method 11 for producing soda percarbonate, characterized by adding at least one type of acid selected from acids or salts thereof and granulating them.
The method (3) according to claim 1, wherein the silicate is selected from No. 1 to No. 3 water glass, potassium silicate, lithium silicate, powdered sodium silicate, and magnesium silicate. The organic polycarboxylic acid is citric acid. Acid, succinic acid. tartaric acid, oxalic acid, cuctonic acid, lactic acid, malonic acid,
! 1. Process according to Claim 1+41 Hydrosyl silicate or silicate or hydrous aluminum oxide is added to sodium percarbonate as Bias or AjgOs of 0.01 to 0.5. %
(weight) Adding phosphoric acid or its salt, boric acid or its salt, and organic polyhydric carboxylic acid or its salt to sodium percarbonate
．． Claim 1 to add 01 to 0.5% (by weight)
Method described in section