JPS5924084B2 - Method for producing granular sodium percarbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing granular sodium percarbonate, and more specifically, a method for producing granular sodium percarbonate. The present invention relates to a method for producing granular sodium percarbonate having extremely excellent properties.

It is known as a sodium percarbonate bleach or oxidizing agent, and is a typical oxygen-based bleach along with sodium perborate.It is generally manufactured by adding 1 part sodium carbonate and 1 part hydrogen peroxide. , general formula 2Na2CO3・3H2
It is represented by 0□.

Unlike sodium perborate, sodium percarbonate exhibits excellent bleaching properties even at low temperatures.

On the other hand, compared to chlorine bleach, the bleaching effect at room temperature is slower, but it will not yellow even when applied to synthetic fibers, animal fibers, resin-treated fibers, or fibers treated with optical brighteners. It has the advantage of not damaging fabrics, and can achieve a sufficient bleaching effect by applying heat or using decomposition accelerators, so it is widely used as a bleaching agent for household and industrial use. There is.

Particularly, the reason why sulfur percarbonate is attracting attention as a general detergent and household bleach is that its decomposition products are non-polluting, and they also pose no problems when used in any way. The point is that it can be put into practical use without any problems.

Conventionally, the method for producing sodium percarbonate has been to mix a predetermined amount of sodium carbonate and hydrogen peroxide, and to crystallize percarbonate from an aqueous solution. In such a production method, the production of fine powder is unavoidable.As a method to improve the drawback of the production method for Kava-filtered sulfur-IJium carbonate, 1-Hypercarbonate sulfur-IJ is used until the drying process after crystallization. There is a method of granulating aluminum.

However, granular sodium percarbonate manufactured using conventional granulation technology does not have sufficient mechanical strength even if its solubility is improved, and transportation of dried sodium percarbonate is difficult. During blending, the granules are often destroyed and crushed, resulting in fine powder, and the specific gravity of loosening (the initial specific gravity when poured into a container) and solidifying specific gravity (the specific gravity of the closest packed state)
The difference is large, causing problems with the porosity after filling the bottle, and the fine powder of sodium percarbonate often unnecessarily irritates the respiratory organs of the handler.

Conversely, if the mechanical strength is increased to eliminate the above problems, the dissolution rate will be significantly slower when dissolved in water.
For this reason, the granular sodium percarbonate has the disadvantage of being in contact with clothing etc. in water for a long period of time, causing discoloration of colored patterned clothing.

In this way, in the production method of granular sodium percarbonate, the reality is that the technology to achieve both solubility and mechanical strength has not yet been perfected, and the compressive strength in the storage tank is high, making it difficult to collapse during transportation etc. The development of granular sodium percarbonate which is durable and has excellent solubility in water has been eagerly awaited.

Therefore, the present inventors have developed granules that have contradictory properties such as excellent mechanical strength (compressive strength, disintegration) and high dissolution rate in water, and also have excellent thermal stability and humidity stability. As a result of extensive research in order to obtain sodium percarbonate in The present invention has been completed based on the discovery that the above object can be achieved by adding and mixing a carbonate or a polysaccharide or a derivative thereof in step 2) and performing granulation.

That is, the present invention performs reaction crystallization of sodium carbonate and hydrogen peroxide in the presence of a silicate, a magnesium salt, and an alkali metal salt of ethylenediaminetetraacetic acid or a triethanolamine salt, and produces 75 to 92 parts by weight of sodium percarbonate. This is a method for producing granular sodium percarbonate, which comprises separating a cake consisting of 25 to 8 parts by volume of mother liquor, and then adding and mixing a carbonate or a polysaccharide or a derivative thereof to the cake and granulating the cake.

In the first step of the present invention, light ash, tenth ash, etc. are used as sodium carbonate, and hydrogen peroxide is
A concentration of ~70% by weight (hereinafter referred to as %) is used, but in practical terms, a concentration of 60% is preferred in terms of availability, safety, and water balance.

The mother liquor region where sodium percarbonate is produced is preferably an aqueous solution containing 6 to 15% Na2CO3 and 1.5 to 6% H20□.

Therefore, in order to obtain homogeneous sodium percarbonate, it is most desirable to add one portion of sodium carbonate and hydrogen peroxide so that the composition of the mother liquor aqueous solution always remains within the above range.

It is necessary to carry out the reaction in the first step in the presence of a stabilizer.

As a stabilizer, sodium orthosilicate (2Na20
・5i02・XH20), sodium metasilicate (Na2
0・SiO2・XH20), sodium silicate (Na20
- ySiO□); a magnesium salt such as magnesium sulfate; and an alkali salt such as an alkali metal or triethanolamine salt of ethylenediaminetetraacetic acid (EDTA).

These three components are essential for achieving the purpose of the present invention, and even if one of these components is missing, a sufficiently satisfactory effect cannot be obtained.

These three components act synergistically to produce the effects of the present invention, but of these, the lack of magnesium salt particularly reduces humidity stability, and the lack of silicate results in poor thermal stability. This has an adverse effect on properties and reduces mechanical strength.

In addition, EDTA interacts with magnesium salts and silicates to further improve the stability of sodium percarbonate, and without it, a product with sufficient heat and humidity stability cannot be obtained. .

These stabilizers are based on 1 kg of produced sodium percarbonate, silicate is 2 to 50 mmol as Si, magnesium salt is 1 to 50 mmol as Mg, and alkali metal salt of ethylenediaminetetraacetic acid or triethanolamine salt is 0.
．． It is preferable to add it in an amount of 0.05 to 5.05.

The thus generated sulfur percarbonate is separated by centrifugation, etc. into sodium percarbonate of 75 to 92 mm and mother liquor of 25 to 8 mm.
Separate as a cake.

If the ratio of mother liquor exceeds 25%, it will become like somen noodles, and when dried, it will become block-like and difficult to dry, resulting in poor yield, and if it is less than 8%, there will be a lot of fine powder, resulting in a decrease in yield. .

This cake is then subjected to the second granulation step,
One cake is added with carbonate or polysaccharide or its derivative.

Examples of the carbonate include sodium carbonate and tun sodium carbonate.

Examples of polysaccharides include starch, gelatin, dextrin, molasses, sodium alginate, etc., and examples of derivatives thereof include modified products such as hydroxyethyl cellulose, carboxymethyl cellulose,
Examples include hydroxypropyl cellulose.

Among these, sodium carbonate, starch, and carboxymethyl cellulose are particularly preferred.

In the case of carbonates, the addition meter for these substances is 20 to 98% of the solid content of the cake (the remainder after removing the volatile part).
Section 2: In the case of polysaccharides or derivatives thereof, it is preferable that the solid content is 10 to 0.2% with respect to 90 to 99.8%.

This addition and mixing is generally performed using a known mixed solution.

These substances must be added during the granulation process,
Even if it is added at the reaction crystallization stage of the first step, the effects of the present invention will not be achieved.

In other words, the carbonate or polysaccharide or its derivatives exhibit their effects only when added to a cake of sodium percarbonate containing an appropriate amount of mother liquor.

By granulating and drying the mixture thus obtained, granular t-IJ percarbonate satisfying the above conditions can be obtained.

Granulation is generally carried out by known methods, among which extrusion granulation is most preferred.

Examples and reference examples of the present invention will be described below.
The present invention is not limited to these G).

Example 1 H20□3.5%, Na2CO39.98% and 3 in water
No. silica soda (Na2O.3 Si02) as Si, 7.5 mmol/kg - mother liquor, magnesium sulfate (Mg
S04゜7H20) as Mg 7.5 mmol/kg
- the mother liquor and also the triethanolamine salt of EDTA (ED
To the reaction mother liquor 137 obtained by adding and dissolving 0.15% of TA-2TEA), 91 60% H2O2 was added at 26.7ky/
hour, Na2CO3 23.6kg/hour, Na2O・3S
205 mmol/hour with iO2 as Si, MgSO4.
7H20 as Mg, 344 mmol/hour, EDTA-
2TEA was continuously added at a rate of 0.0684 kg/hour, and the produced and aged slurry was continuously taken out from the reaction vessel.

The production amount of sodium percarbonate is 35.0 per hour in terms of dry matter removal.
It was 9.

A portion of the reaction mother liquor was separated from the slurry using a centrifuge to obtain a cake containing 85% sodium percarbonate.

Next, add N a 2 CO to 88 parts of the solid content of this cake.
A 7 parts by volume were mixed and granulated using an extrusion granulator (screen opening diameter: 1φ), and then dried with hot air to obtain granular sodium percarbonate.

For comparison, granular sodium percarbonate was also produced in the second step by granulating and drying without adding Na2CO3.

The solubility, compressive strength, disintegrability, thermal stability, and humidity stability of the obtained granular sodium percarbonate were investigated.

The results are shown in Table 1. (Si in sodium percarbonate
(Mg was 93 ppm, Mg was 212 ppm) (Test method) <Solubility> Put tap water 11 into a beaker (1 liter volume), add 1 g of granulated sodium percarbonate, and stir at a rotation speed of 200 ml) was carried out.

After the start of stirring, the time required until the tonality of the solution stopped changing was measured, and this time was taken as the dissolution time.

<Compressive strength> It is indicated by the charge required to pack a certain amount of sample under specified conditions, load it using an autograph, and compress it by 1 cIrt.

<Disintegrability> Sample (12 meshes permeable to 80 meshes opaque) 100
Take 500 g in a wide Ropoly container and add a stainless steel ball (
Pour 3φ) 50g and stopper.

Fix this container on a shaking machine and shake with an amplitude of 4.5J for 3 times.
Shake at 60 times/min for IO minutes and express by weight of 80 meshes transmitted.

A smaller number (%) is desirable.

Humidity Stability> It is shown as the effective oxygen residual rate after being left at 40°C and 80% relative humidity for 6 days.

<Thermal stability> It is shown as the effective oxygen residual rate after storage at 50° Cl2O.

Example 2 In the first step of Example 1, among the stabilizers used, one chelating agent was used, but the type was changed, and the thermal stability, humidity stability, and dissolution of sodium percarbonate prepared by the method shown in the following 1. I looked into gender.

The results are shown in Table 2.

**(Sample preparation method) 624g of ion exchange water, N
a2 CO366a, 60%H20□52g, 38 Section No. 3 Sodium Silicate 4.7g, Mg5O, 7H201,8
, 9 and below t Take 750 g of a reaction mother liquor consisting of 1.5 g of the chelating agent shown above, maintain the mother liquor temperature at 20 °C, and
0rl) Without stirring with In, Na2 co3139 &
, 111 g of 60% H202 was added continuously over 30-90 minutes to produce sodium percarbonate.

After aging the resulting slurry for 30 to 60 minutes, the reaction mother liquor was separated using a centrifuge, and the resulting cake was dried at 60'C for 2 hours, and dried ungranulated percarbonate l-IJum 195
．． 1g was obtained.

(Test method) <Thermal stability> Same as Example 1 <Humidity stability> Same as Example 1 <Solubility> Pour tap water 11 into a beaker (11 volume) and add 1 g of granular sodium percarbonate. After starting stirring at a rotational speed of 20 rpm, the time until the percarbonate disappears is measured by visual observation, and this is determined as the dissolution time.

The liquid temperature is kept constant at 20°C.

Example 3 In the first step of Example 1, among the stabilizers used (silicate), the type was changed and the thermal stability, humidity stability, and dissolution of sodium percarbonate was prepared by the method shown below. I looked into gender.

The results are shown in Table 3.

(Sample preparation method) Na2CO366g, 60% H20252g, Mg
SO4・7H201.8g and chelating agent (EDTA-
2TEA・2H20) 1.5 g of sodium percarbonate was reacted by adding the following silicate and ion-exchanged water so that the Si content in the slurry at the time of crystallization was 22.5 ml J mol/yu-slurry. Prepare 750 g of mother liquor, then maintain the mother liquor temperature at 20°C for 1 hour, and add 139 g of Na2CO3 and 111 g of H2O2 to 60% while stirring at l 5 orpm.
Continuous additions were made over 0 to 90 minutes to produce sodium percarbonate.

The resulting slurry was treated in the same manner as in Example 2 to obtain 195.8 g of dry, ungranulated sodium percarbonate.

(Silicate) 1. Sodium orthosilicate 2Na20・SiO□・xH
20X=4.732, sodium metasilicate Na2O・
SiO2.xI7I20 X=93.1 Sodium silicate Na2()ysio2 y=2.11 Same as Example 2.

Example 4 A 15 mmol solution of H20□3.5%, Na2C039.98% and No. 3 silica (Na20.3SiO2) as Si in water, magnesium sulfate (MgSO,.7H)
20) as Mg 7.5 mmol/Kg - mother liquor 1C
Ef) To 137 kg of the reaction mother liquor obtained by adding and dissolving TA-2TEAO, 15%, 20.6% of 60% hydrogen peroxide solution was added.
9/hour, Na2CO3 at 24. l ky/hour, N
a 20" 3 S102 as Si was added continuously at a rate of 610 mmol/hour, MgSO4.7H20 as Mg was added at a rate of 338 mmol/hour, and EDTA-2TEA was added at a rate of 0.0335 y/hour, and the produced and aged slurry was reacted. The amount of sodium percarbonate continuously removed from the tank was 34.8 kg/hour based on dry weight i.

A part of the reaction mother liquor was separated from the slurry using a centrifuge to obtain a cake containing 87 parts of sodium percarbonate.

Next, 37 parts by weight of Na 2 C0 was mixed with 88 parts by weight of the solid content of this sodium percarbonate cake, and granular sodium percarbonate was obtained in the same manner as in Example 1.

The solubility, compressive strength, disintegrability, thermal stability and humidity stability of the granular sodium percarbonate thus obtained were investigated in the same manner as in Example 1.

The results are shown in Table 4. In addition, during granulation, Na2CO3
Granular sodium percarbonate prepared without the addition of was used as a control.

(Si in sodium percarbonate is 367 ppm.

(Mg was 267 ppm) Example 5 Water, H2O23.5%, Na2co39.98'
% and Na 20 ・3 S t 02 as Si 22.5 mmol/kg - mother liquor, Mg5O, ・7H20
7.5 mmol/kg as Mg - mother liquor, further EDT
To 137ky of the reaction mother liquor obtained by adding and dissolving 0.15% of A-2TEA, 60% hydrogen peroxide solution was added at 26.8kg/hour, Na2COa was added to 23.0% at 9/hour, Na2O.
3SiO2 as Si, 1198 mmol/hour, MgS
O4.7H20 as Mg 2 mmol/hour, ED
TA-2TEA was continuously added at an addition rate of 0.0456 to 7 hours, and the produced and aged slurry was continuously taken out from the reaction vessel.

The production amount of IJium (percarbonate) was 34.8 kg/hour in terms of dry weight.

A part of the reaction mother liquor was separated from the slurry using a centrifuge to obtain a cake containing 87 parts of sodium percarbonate.

Next, the solid content of this sodium percarbonate cake was 88 parts t.
0.5 t of carboxymethyl cellulose Na salt was mixed with 7 parts by weight of Na2CO or 99.5 parts by weight of the solid content of the sodium percarbonate cake, and the following is Example 1.
Granular sodium percarbonate was obtained in the same manner as above.

The solubility, compressive strength, disintegration, thermal stability, and humidity stability of the two types of granular percarbonate thus obtained were examined in the same manner as in Example 1.

The results are shown in Table 5.

Note that granular sodium percarbonate produced without adding Na2CO3 during granulation was used as a control.

(Si in sodium percarbonate is 543 ppm.

(Mg was 260 ppm) Example 6 1 bottle of water, H20□3.7%, Na2COs 9.50
% and No. 3 silica (Na20 .3 S t 02 ) as Si, 7.5 mmol/kg - mother liquor, magnesium sulfate (M g S 04 .7H20) as Mg, 5.
0 mmol/kg - mother liquor plus EDTA-2TEA0.
Reaction mother liquor 137ky obtained by adding and dissolving 1'7%)
21.81y/hour of 60% hydrogen peroxide solution, Na2C
O3 at 25.2 kg/hour, Na2O・3SiO2 at Si
191 mmol/h, MgSO4.7H20 as M
g as 402 mmol/hour, EDTA-2TEA 0
．． The slurry was continuously added at a rate of 0.220 kg/hour, and the produced and matured slurry was continuously taken out from the reaction tank.

The production rate of sodium percarbonate is 35% per hour by dry weight.
．． It was OK.

A portion of the reaction mother liquor was separated from the core slurry using a centrifugal trowel to obtain a cake containing 86.5 parts by weight of sodium percarbonate.

Next 1 Solid content of this sodium percarbonate cake (hereinafter referred to as PC)
A mixture of carbonate or carboxymethyl cellulose (hereinafter referred to as CMC) in the following ratio was granulated in the same manner as in Example 1 and dried to obtain granular sodium percarbonate.

■88 parts by weight of PC] vs. 39 tons of Na2C037 parts■
1 part by weight of PC99.5: 0.5 parts by weight of CMC Na salt; 1 part by weight of PC98: 2 parts by weight of CMC Na salt.
2 parts by weight of Na salt of CMC for 98 parts by weight of PC
Sodium bicarbonate (NaHC) for PC98 tonne part I
2 parts by weight of O2) ■ 1 part by weight of 88 P'C 99.5 tons of a mixture of 37 parts by weight of Na2CO Part B) 0.5 parts by weight of CMC Na salt
Parts by weight ■ 2 parts by weight of starch for 98 parts by weight of PC; for comparison, sulfuric acid for only PC or 98 parts by weight of PC)
A mixture of IJum (Na2804) 2 taken out was granulated in the same manner as in Example 1 and dried to produce granular percarbonate l-IJum.

The solubility, compressive strength, disintegrability, thermal stability, and humidity stability of the obtained granular sodium percarbonate were investigated.

The results are shown in Table 6. (Si in sodium percarbonate
is 73 ppm, Mg is 284 ppm, EDTA-
2TEA was 159 ppm.

Claims (1)

[Scope of Claims] 1. Performing reaction crystallization of sodium carbonate and hydrogen peroxide in the presence of silicic acid, a magnesium salt, and an alkali metal salt or triethanolamine salt of ethylenediaminetetraacetic acid,
75-92 parts by weight of t-IJ percarbonate and 25-92 parts by weight of mother liquor
1. A method for producing granular percarbonate, comprising separating a cake consisting of 8 parts, and then adding and mixing the cake with carbonate and a polysaccharide or a derivative thereof and granulating it. 2 Generated percarbonate) For 1 kg of IJum, the silicate is 2 to 50 mmol as Si, and the magnesium salt is Mg.
1 to 50 mmol, and 0.05 to 50 mmol of the alkali metal salt or triethanolamine salt of ethylenediaminetetraacetic acid.
5. The manufacturing method according to claim 1, characterized in that the steamed rice cakes are prepared in one volume. 3. Claim 1, wherein the amount of carbonate added is 20 to 2 parts by weight per 80 to 98 parts by weight of the solid content of the cake.
Manufacturing method described in section. 4. The manufacturing method according to claim 1 or 3, wherein the carbonate is sulfur carbonate. 5. The manufacturing method according to claim 1, wherein the amount of the polysaccharide or its derivative added is 10 to 0.2 weight percent based on the solid content of the cake, 90 to 99.8 weight percent. 6. The manufacturing method according to claim 1 or 5, wherein the polysaccharide is starch. 7. The production method according to claim 1 or 5, wherein the polysaccharide derivative is carboxymethyl cellulose.