JPS5983912A - Production of stable sodium percarbonate - Google Patents

Abstract

PURPOSE:To form sodium percarbonate having improved stability and shelf stability, by treating sodium percarbonate powder with a coating agent containing a borate. CONSTITUTION:Sodium percarbonate powder wetted with water is smeared with about 0.04-10wt%, based on the dry sodium percarbonate expressed in terms of boron, borate, e.g. sodium tetraborate decahydrate having about 50-300mu particle diameter, and the resultant treated sodium percarbonate powder is dried at the melting point of the borate or above to give the aimed sodium percarbonate powder coated with the borate on the surface thereof. Preferably, a sequestering agent, e.g. an ethylenediaminetetraacetate, is used together with the borate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides fI
! It is related to the method of construction. Furthermore, liver 1. <( treatment of soda percarbonate powder with a borate-containing coating agent!~) turns into a method for producing stable soda percarbonate rather than coating the surface with #!~.

Sodium percarbonate is well known as a bleaching agent or oxidizing agent, and is generally produced by reacting a tricarbonate sorter with hydrogen peroxide, and has the general formula: 2NF12Co,...
! Hydrogen peroxide is added to soda carbonate as shown by 5H,,02. Soda percarbonate has a slightly slower bleaching effect than chlorine bleach at room temperature, but it can also be used to bleach colored and patterned fabrics, and it does not damage fabrics or cause them to change color! : etc., it is widely used as an oxygen-based 77 whitening agent for household or commercial use, either alone or in combination with V1 detergent.

The reason why percarbonate sorter is attracting attention as a general detergent and household bleach is that it can be put to practical use in any way without any problem, both in 1-J2 and 1,000 decomposition products that are non-polluting. However, compared to sodium percarbonate and sodium peroxide, it has a major disadvantage in that it has considerably poor storage stability and loses effective oxygen quite quickly during storage. Sodium percarbonate has a strong affinity for water, so even slight moisture from the stitches causes the surface to absorb moisture, decomposition occurs, and iron and copper are added to this system.

If elements such as manganese and cobalt are present, Kij
, further decomposition is promoted and its stability is a disaster? 1I
Inferior to sodium fluoride. If sodium percarbonate is stored alone in a sealed container, its storage stability will be the same as that of sodium perborate, but if it is mixed with detergent or left unopened, sodium percarbonate will become less soluble. Despite its good properties, it has high hygroscopicity and poor storage stability.

Therefore, decomposition will not be accelerated even if left unopened, and even when mixed with any detergent or bleaching composition, practical problems regarding storage stability will not occur. It is desirable to provide supercarbonated soda.

Many studies have been conducted on methods for stabilizing soda percarbonate, and various methods have been proposed. In particular, many proposals have been made for methods of coating soda percarbonate with organic substances or heated substances. It has been found that stable sodium percarbonate can be obtained and has extremely excellent storage stability. In particular, it has been found that the sodium percarbonate powder whose surface is coated with a borate according to the present invention has extremely excellent storage stability when combined with a detergent. In doing so, it is desirable that the coating be completely coated with the sodium percarbonate or nal borate; uneven coating may reduce its stability. The present inventors have discovered a method for producing borate-coated soda percarbonate that is industrially easy to implement and consumes little energy, with a complete coating of borate. result,
It was demonstrated that a desired coating of sodium percarbonate7) could be obtained by utilizing the characteristics of the 17 m average during the coating process.

That is, according to the present invention, sodium percarbonate powder is coated with a borate-containing coating agent to form IJn4N711. The most advantageous method for coating the surface of a percarbonate sorter is to mix and adsorb the coating powder containing borosalt onto a wet n-shaped percarbonate sorter moistened with water; When h- is melted with boric acid, 1,
This method involves drying at a temperature higher than the cooling temperature.

In this case, the borate is desirably a borate having water of crystallization, and can be used in the present invention. times, 0.2B,,O,.1120).

5 liters of sodium tetraborate (>ra2o-2B,,o,・5
n2o3.

Tetrahoray M 7- p-4 hydrate r Ha, 0.2
．． ['+20.・4FT20).

Sodium octaborate 4 water + x, cr p, , o-
4p, 2a, 4H2o>.

Sodium pentaborate 5 water JI C) la,, 0' 5B
20.・10H,,O).

Me, J * U/! 9 Sorb tetrahydrate salt (uFl, no2
・4H2o), sodium meborate dihydrate (N a B
o 2.2H20), etc., and among these, the most preferred are sodium metaborate dihydrate, tetrahydrate, and sodium tetraborate decahydrate.

In the advantageous coating method of the invention described above, a powder of boron salt with water of crystallization is sprinkled on wet sodium percarbonate, and this is applied to the melting point of the borate (e.g. Na2B, 07'10H, O
: 75°C, Na, B02'4H20: 57°C.

NeBo ・2HO: 90℃, NaBO, -4H
It is thought that when dried at a temperature of 20:63°C) or 2 or higher, the borate dissolves in its own water of crystallization and becomes molten, completely enveloping the sodium percarbonate.

During this step, the water in the sodium percarbonate and the water of crystallization in the borate evaporate, completing the drying operation.

That is, uniform coating formation and drying steps are performed simultaneously.

Note that sodium percarbonate Vi is usually dried at 40 to 160°C. Although drying can be performed at temperatures below 40°C, the drying time is too long, and at temperatures above 160°C, ineffective decomposition of sodium percarbonate occurs and effective oxygen is rapidly lost. In the present invention, it is preferable to dry at a temperature above the melting point of the borate and below 160°C.

Anhydrous borate salts have a higher melting point than hydrated salts (e.g., N, B, O7: 741°C), but the melting point is the same as that with water of crystallization due to moisture in a humid percarbonate sorter. This lowers the melting point, so it can be used in the present invention, but borates with water of crystallization are preferred. Borate in borate-coated soda percarbonate between t'1, boron as 0.04-I ET % to dry soda percarbonate
Cv+/w), preferably 0.1 to 5% (w/
w). Also, Hourp! Particle size C of salt - The finer the better, but from the viewpoint of workability, it is 50 to 300μ, preferably 100 to 150μ.

Stable percarbonate saw of the present invention! - Wet perphosphorous acid used in the production of t''1 as acid soda, sodium carbonate and hydrogen peroxide are reacted in a conventional manner, and sodium percarbonate, which is dehydrated in a conventional manner, can be used as it is. In other words, this mixed sodium percarbonate contains water for 7 to 1 day, and this water acts as the necessary wet water, so it can be used as is, but it is preferable to use a water content of 10 to 1. This is from Section 16.

In some cases, when using soda percarbonate with a low water content,
It is preferable to moisten the borate powder appropriately with water so that it is evenly sprinkled (1). It is an advantageous method to include in the coating a permanent ion sequestrant, such as the known stabilizers of sodium percarbonate, such as ethylenediaminetetraacetate or IJ-triacetate.

In producing the boric acid group-coated percarbonate sorter of the present invention,
Hou r￥9. Using a salt aqueous solution, mixing lTi'' with the sodium percarbonate powder and drying it covers the sodium percarbonate and the resulting product is as follows:
In this case, since it is necessary to use cartilage sodium percarbonate, it is necessary to perform the drying process twice.

On the other hand, as mentioned above, sodium percarbonate powder, which has been moistened with water as sodium percarbonate, in particular hydrogen peroxide and soda carbonate, is reacted in an aqueous solution and dehydrated [7].
, using acid soda and adding powder to the powder? l? ,
The method that takes advantage of the properties of borates, which performs the #L process of drying the material after adsorption, does not require an operation to dissolve boric acid groups, consumes less energy, and is easy to implement. This is an industrially extremely advantageous method for carrying out the present invention.

As shown in the attached photo of borate-coated soda percarbonate e'1 obtained by the method of the present invention, it was observed that the borate was uniformly coated on the surface of the soda percarbonate particles. Ru. The coated soda percarbonate has an average particle size of 100 to 2000μ, tL<i>250 to 1
000μ powder is preferable.

Figure 1 is a scanning electron micrograph of the uncoated sodium percarbonate particles, Figure 2 is a scanning electron micrograph of the coated soda percarbonate particles, each magnified 100 times, and Figure 3 is a photo of the coated soda percarbonate particles of Figure 2. Enlarged cross-section photo 7! , (440 times), and Figure 3 shows the boric acid layer on the surface.The ones in Figures 2 and 3 were coated with 3.7 chloride of metaborate dihydrate. I'm here.

EXAMPLES The present invention will be described and explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Warm percarbonate solder (moisture 10%) obtained by reacting hydrogen peroxide and soda carbonate in an aqueous solution.

The average particle diameter when dry is 480μ) is 5.3 in a continuous feeder.
kgZ was supplied to the continuous mixer at a rate of 0.178 kf/lI+, and on the other hand, two water bottles of sodium metaborate (average particle size 150μ) were supplied to the continuous mixer at a rate of 0.178 kf/lI+. The residence time in the continuous mixer was adjusted to 5 minutes L % This mixture was continuously fed to a fluidized fluid dryer and dried at 130°C.

The boron content of this carbonated soda was determined to be 0.
．． 42% (as boron). Table 1 shows the stability when the coated soda percarbonate and various second components were mixed. The stability was determined by putting the required amount of sample into a resin container with a pinhole and leaving it at 50℃ and 80% RH for 24 hours. , dry average particle size 400 μ) 3.4 gin and sodium borate decahydrate 0. JKF was placed in a badge type mixer and mixed for 1 minute, and the mixture was dried at 140° C. in a fluidized drying cage. When the boron content of this coated soda percarbonate was set to 0
．． 404 (as boron) 0 For comparison purposes, sodium carbonate and colloidal silica (S10
Select No. 220 product) and No. 3 sodium silicate and weigh 0.16 * 0.78 kg and 0.31, respectively.
The conditions described above were followed except that kg was added. The thus obtained coated soda percarbonate and commercially available detergent AC phosphorus-free detergent (combined with zeolite) were placed in a resin container with a pinhole at a ratio of 9:1.
After mixing at a ratio of 40 T: and 80% RH for two weeks, the effective oxygen residual rate (stability) was measured, and the results are shown in Table 2.

Table 2 Example 3 The coated po coated in Examples 1 and 2 was tested for storage stability under humid conditions.

(1) Commercially available detergent B (phosphorus-free detergent, zeolite combination) coated with PO coated with 10 layers of moisture (2) Commercially available detergent O (phosphorus-containing detergent, Tribo IJ IJ
Coated PC with 10 heavy air (mixed with sodium chloride) and mixed with 10 f of each of these 50 ('). The residual rate was calculated using the following formula.

Measurement of available oxygen Ic+ 0.1N potassium permanganate measurement method was used.

For comparison, in addition to the coated PO according to the present invention, (1) 9PO was prepared by drying the wet Y4PC as it was without applying any coating.
, (2) Sodium perborate (FB) was similarly tested.

[Brief explanation of the drawing]

Figures 1 to 3 are scanning electron micrographs, Figure 1 is a photo of percarbonate soda particles before coating, Figure 2 is a photo of coated soda percarbonate particles, Figure 3 Cj, Figure 2 This is an enlarged cross-sectional photograph.

Claims (1)

[Claims] 1. A method for producing stable soda percarbonate, which comprises treating the surface of sodium percarbonate powder with a coating agent containing a borate. 2. Sodium percarbonate powder is a powder moistened with water, and after coating powder containing borate is mixed and adsorbed to wet sodium percarbonate, it is heated to a temperature at which the borate starts to melt. Claim 1 which performs a drying process at a temperature above
Manufacturing method described in section. 3. Soda percarbonate powder moistened with water has a water content of 7 to 18% by weight obtained by dehydrating hydrogen peroxide and soda carbonate in an aqueous solution [Claim 2] Manufacturing method described. 4. The first range of special WrR old wood where the it of borate relative to sodium percarbonate is 0.04 to 10 times as boron.
The manufacturing method according to any one of Items 1 to 5. 5. The manufacturing method according to claim 1 or 1 of claims 1 to 4, wherein the coating material includes a gold pion sealant 1911 agent. 6. 9 according to claim 5, wherein the Kinkuku Ion Tsukisen agent is ethylenediaminetetraacetic acid Hanamata e or nitrilotriacetate. Construction method. 7. The average particle diameter of the coated soda percarbonate powder is 100~
2nooμ. The manufacturing method according to any one of claims 1 to 6. 8. Claim VJ1 No. 1 in which the boron salt is a borate having water of crystallization! Any of N-M7 is the manufacturing method according to Item 1. 9. The production method according to claim 8, wherein the borate having water of crystallization is sodium mekporate 2 water or tit 4 water. 10. The borate with water of crystallization is sodium borate 1° hydrate 'I? Fl'r manufacturing method according to claim 8. 11. The manufacturing method according to any one of claims 2 to 10, wherein the borate powder has a particle size of 5o to 300μ.