JPS6096511A - Production of stabilized granular sodium percarbonate - Google Patents

Abstract

PURPOSE:To produce granular sodium percarbonate having excellent slubility and storage stability, easily, by reacting Na2CO3 with H2O2 in an aqueous solution containing a silicate, etc., and adding a specific amount of a stabilizer such as a solicate to the obtained crystal. CONSTITUTION:Granular sodium percarbonate having an average particle diameter of 150-2,000mu can be produced by reacting Na2CO3 with H2O2 in an aqueous solution containing at least the above components in the presence of 0.005- 0.5(wt)% silicic acid (in terms of Si), 0.005-0.1% magnesium salt (Mg), and 0.005-0.4% phosphoric aicd or phosphate (P), based on the produced sodium percarbonate. The produced granular sodium percarbonate is separated, mixed with a stabilizer containing two or more components selected from 0.005-0.1% silicic acid (Si), 0.005-0.2% magnesium salt (Mg) and 0.05-0.6% phosphoric acid or phosphate (P), based on the dried weight of the sodium percarbonate, and dried to obtain the stabilized product.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing granular sodium percarbonate having excellent solubility and storage stability. Sodium percarbonate (2N a, COa, 3H,0,), which is obtained by reacting hydrogen peroxide and sodium carbonate by various methods, is used as a non-polluting oxygen bleaching agent with excellent low-temperature bleaching performance. Alternatively, it is a substance widely used for various purposes that takes advantage of its oxidizing properties, and is usually produced in the form of easy-to-handle granules or particles.

As a method of giving these forms, in the case of granules,
A method of secondary granulation of fine crystalline sodium percarbonate using various granulation methods is used, and for non-granular sodium percarbonate particles, sodium percarbonate is granulated from sodium carbonate and hydrogen peroxide. A method has been adopted in which various crystal modifiers are co-present during reaction crystallization to directly crystallize as particulate sodium percarbonate.

Due to these manufacturing differences, the appearance, abrasion resistance, and solubility of the resulting sodium percarbonate particles vary greatly, with the former generally having better solubility and the latter having better solubility. It has excellent appearance and wear resistance. However, as a matter of course, it is desired that these materials be satisfied in all practical aspects, regardless of the manufacturing method used.

On the other hand, supercarburized patchtrium contains trace amounts of impurities and other co-Hvc that are inevitably mixed in from its raw materials.
Therefore, it has the inherent drawback that its stability during storage is easily affected, and in order to improve these drawbacks, silicates, macrosium salts, phosphates, or various organic A method of stabilizing by adding a chelating agent alone or in combination when producing sodium percarbonate;
Alternatively, there is a method of stabilizing the particle surface of granular or granular sodium percarbonate by coating it with an organic or inorganic substance that is inert against the decomposition of silicate or hydrogen peroxide components and removing it from moisture and foreign substances. Proposed. However, in the case of the former, when particles or crystals of a specific shape are desired, the use of stabilizers is restricted because each stabilizer has a so-called mode crystal effect that modifies the crystal habit. In addition, even in the latter case, in order to achieve sufficient force stabilization, complete coating is required and a relatively large amount of coating material is required. There was a problem that the solubility of the particles was significantly impaired.

In view of these points, the present inventors have developed a method for producing granular sodium percarbonate obtained by reactive crystallization without impairing its morphological characteristics.
As a result of research on a method for producing sodium percarbonate with excellent solubility and high storage stability by a simple means, it was found that silicate was added to granular sodium percarbonate with a water content of 30% by weight or less obtained by reaction crystallization. By using at least 2s selected from , magnesium salt, phosphorus rIi/or phosphate, and dispersing their powder or aqueous solution in an extremely simple operation, the storage stability can be improved without impairing the solubility of the particles. The present invention has been completed based on the discovery that significant improvements can be made.

That is, the present invention produces silicate, red sea bream sium salt, phosphoric acid, or phosphate when sodium carbonate and hydrogen peroxide are reacted and crystallized in at least water containing them. 7 for each sodium percarbonate, respectively Sl
As 0.005~05 weight ratio, as Mg 0005~
Add 0.1well E4CH, P at a ratio of 0.005 to 0.4% by weight to produce granular sodium percarbonate with an average particle size of 150 to 2000 microns, separate this, and after drying or Moisture content 30 small-h obtained without drying
4% or less of granular sodium percarbonate and at least two selected from silica salt, machinic salt, phosphoric acid, or phosphate salts are added to the SL of each sodium percarbonate dry oil amount.
0.005~0.1% as Mg, 0.005~0.1% as Mg
The present invention provides a method for producing granular sodium percarbonate having excellent solubility and storage stability, characterized in that P is added at a ratio of 0.2% and 0.05 to 0.6% as P.

In the present invention, granular sodium percarbonate is carbonated)
sodium carbonate, in a mother liquor containing hydrogen peroxide, or in a mother liquor having a controlled composition with further intervention of a salting-out agent such as sodium chloride to reduce the amount of sodium percarbonate dissolved in the mother liquor. It is produced by continuously reacting and crystallizing the sodium percarbonate and hydrogen peroxide.

Phosphoric acid compounds such as birophosphoric acid, hexametaphosphoric acid, or their salts are coexisting in the reaction crystallization system as a so-called crystal modifier. In order to stabilize hydrogen oxide and improve the yield, in addition to phosphoric acid compounds, silicates such as sodium orthosilicate, sodium metasilicate, various hydrolases, and magnesium salts such as magnesium chloride and magnesium sulfate are used as stabilizers. It will be done. Each of these agents added during reaction crystallization has a strong influence on the shape of the sodium percarbonate crystals produced, and also greatly changes various properties such as solubility. Si for each of the silicate, magnesium salt, phosphoric acid or phosphate
As 0.005~0.5i-Qt%, Mg (!
: Lte 0.005~0.1i-i%, P as o,
It is added in a limited amount of 0.4 weight % to 0.4 weight %.

In the reaction crystallization process, granular sodium carbonate with an average particle size of 150 to 2000 microns is generated with a residence time of 20 minutes to 4 hours, and is separated from the mother liquor by fJ filtration, which results in wet particles. The moisture content in
Considering the efficiency of dispersion and impregnation of the stabilizer in the subsequent secondary stabilization step and changes in agglomeration or particle shape and physical properties due to moisture, the amount is 30 μl or less, preferably 30 μl.
The concentration is adjusted to ~20% by weight, and the e-filtrate is subjected to reaction crystallization again. The separated sodium percarbonate is subjected to a secondary stabilization process, either in a wet state or after drying, to form silicate, magnesium salt, and phosphorus CV.
Sodium percarbonate particles are dispersed and impregnated with l or phosphate as a stabilizer. The silicate added at this time is orthosilicic acid.

In addition to water-soluble silicates such as Na salts such as metasilicic acid and various water glasses, insoluble silicates such as magnesium silicate can also be used, but unless specifically desired, it is preferable to use water-soluble silicates. preferable. Magnesium salts such as magnesium sulfate and magnesium chloride are used as stabilizers, and phosphoric acid or phosphates include orthophosphoric acid, birophosphoric acid, tripolyphosphoric acid, or their Na, K, H, and NH4 salts as stabilizers, respectively. I can give an example. Stabilizers are 8i and 0.0%, respectively, based on the dry weight of sodium percarbonate.
005 to 0.1%, 0.005 to 0.2 chi as Mg,
P is 0.05 to 0.6 inches, preferably 0.05 to 0.6 inches respectively.
01~0.05 inch, 0.01~0.1 inch.

It is added and impregnated at a rate of 0.1 to 0.4%. When the amount of silicate added exceeds 0.1 inch as Si, the dissolution rate is significantly delayed, and the amount of added magnesium salt is
If it exceeds 0.2%, a sufficient stabilizing effect cannot be obtained.

Examples of operations for adding and impregnating the stabilizer with IJum are a ■-type mixer and a ribbon mixer.

Using a known batch or continuous mixer or mixer such as a screw mixer, paddle mixer, or airflow type mixer, IJum is supplied in both a wet state and a dry state, and is stabilized. Add an aqueous solution or powder of the agent to increase the water content of sodium percarbonate to 30%.
Hereinafter, mixing is generally carried out by adjusting the amount preferably to 3 to 20%. This operation is not particularly limited in terms of the method, loading, water content of sodium percarbonate, etc., as long as the stabilizer is sufficiently dispersed in the sodium percarbonate particles. The use of equipment with a tendency to pressure or kneading is not appropriate unless specifically desired, since this may lead to particle destruction, agglomeration or changes in physical properties in relation to the moisture content.

Through this operation, the stabilizer is dispersed on the surface of the sodium percarbonate particles and impregnated inside the particles, but these substantially proceed during the drying process until the water is removed. The time required to complete the drying process after adding and mixing the stabilizer and then removing water by drying is 1 to 9 minutes.
It is desirable to carry out the process so that the time is 0 minutes.

According to the present invention, highly stabilized sodium percarbonate with high practicality can be produced by an extremely simple method without impairing the properties of granular percarbonate (IJ).

The present invention will be explained below with reference to examples, but the present invention is not limited to these examples.
Using mother liquor 1501 having a composition of wt%, hydrogen peroxide concentration Q, and 7wt, granular sodium carbonate was added at 30.0 kg/hr while stirring, and 60 wt% hydrogen peroxide was added to 24.9wt% at 9/hr. No. 3 sodium silicate 0.
18 kg/hr, 30 wt% magnesium sulfate solution 0.098 klF/hr, 30 wt% sodium dihydrogen phosphate solution 0.2 kg/hr,
20 wt qb sodium hexametaphosphate solution was continuously fed at a rate of 0.51 kfl/hr, while sodium chloride was replenished to maintain its initial concentration, the reaction temperature was 25 °C, and the average residence time of the slurry was 70 °C.
After centrifugation, the slurry is taken out from the reaction vessel for 3 hours, and after centrifugation, the P solution is circulated through the reaction vessel for 3 hours of continuous reaction. The resulting granular particles with an average particle diameter of 694 microns and a water content of 13.2% (A) were mixed with sodium carbonate using a Rihon mixer, and various stabilizers were added to the mixture, immersed in the mixed gold for 3 minutes, and then fluidized for 30 minutes. The results of measuring the storage stability and dissolution time of the products obtained are shown in Table 1.The determination method is as follows.Pour 2 g of a known sample of effective oxygen-containing oil into a styrene container. After leaving it open for one week at 40° C. and 80% relative humidity, the remaining effective oxygen was measured, and the residual rate was calculated from the ratio to the effective oxygen content before leaving.

(Dissolution time) Pour 1 liter of tap water into a beaker No. 11, stir at a stirring speed of 200 rpm, add 1 g of the sample that has passed through a 20 mesh sieve, and wait until the conductivity of the solution stops changing. The time was measured.

Examples 9 to 14 The reaction to produce IJium (granular percarbonate) was carried out at a sodium carbonate concentration of 13.0 Wt and hydrogen peroxide of 3.4 wt%.
The reaction was carried out in the same manner as in Example 1 for 3 hours, except that mother liquor 1501 having the composition was used, and sodium chloride and sodium dihydrogen phosphate were not used. Using dry sodium percarbonate with an average particle size of 625 microns, this was continuously fed to a paddle mixer at 1-15%, and the residence time in Mikitsu was 3 minutes. The storage stability and dissolution time of the product obtained by drying the sodium again were as shown in Table 2.

(Storage stability) It is shown as the effective oxygen residual rate after being left at 40° C. and 85% relative humidity for a week.

(dissolution time) Same as Examples 1-8.

Claims (1)

[Claims] 1. When reacting and crystallizing sodium carbonate and hydrogen peroxide in an aqueous solution containing at least them, Si as 0.005
~0.5% by weight, 0005~0.1% by weight as Mg,
P is added in a proportion of 0.005 to 0.4% by weight to produce granular sodium percarbonate with an average particle size of 150 to 2000 microns, which is separated and obtained after or without drying. At least two kinds selected from silicates, magnesium salts, phosphoric acid, or phosphates are added to the granular sodium percarbonate having a water content of 30% by weight or less, each with an Si content of 0.005% based on the dry weight of the sodium percarbonate. ~0
．． 1%, 0.005 to 0.2 as Mg, 0 as P
．． A method for producing IJum, a granular percarbonate with excellent solubility and storage stability, which is added at a ratio of 0.05 to 0.6%.