JPS641402B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing sodium percarbonate having excellent storage stability. Sodium percarbonate (2Na ₂ CO ₃・3H ₂ O ₂ ), which is obtained by reacting hydrogen peroxide and sodium carbonate in various ways, has excellent low-temperature bleaching performance and is a non-polluting oxygen bleaching agent. It is a substance that is widely used as an agent or for various purposes utilizing its oxidizing properties, but its stability during storage may be affected by the coexistence of trace amounts of metals and other substances that must be mixed in from the raw materials etc. It has the essential drawback that its properties are significantly affected, and its deterioration tends to become even more pronounced depending on storage conditions such as high temperature and high humidity. In order to improve this practical problem, many stabilization methods have been proposed and implemented in the past, and the content is wide-ranging. Methods for purifying and using raw materials, methods for shielding sodium percarbonate from external influences during storage, such as coating its crystals or particles with inert substances to shield it from moisture and foreign substances, or various stabilizing agents. This can be roughly summarized as a method of making the material harmless by adding . Among these methods, the third method has become a practically essential method due to its industrial advantages and effectiveness, and conventional stabilizers for this purpose have been silicic acid compounds, magnesium salts, and inorganic phosphoric acid. It has been proposed to use either salts or organic chelating agents such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), hydroxycarboxylic acids, polyphosphonic acids, etc. alone or in combination. By using these stabilizers, the storage stability for a short period of time or under conditions of low temperature and low humidity can be made to be suitable for practical use. However, when using conventionally known methods, the stabilizing effect is essentially insufficient or the stabilizing effect is not maintained for a long period of time or when stored under high temperature and high humidity conditions. As a result, I could not expect a satisfactory effect because I did not maintain it. In view of these points, the present inventors conducted extensive research with the aim of producing sodium percarbonate that has excellent stability over time even under conditions of high temperature and high humidity.
By using the following two groups of ingredients, amino acids or a compound composed of amino acids together with a stabilizer consisting of polyphosphonic acids and incorporating them into sodium percarbonate, an unexpectedly high degree of storage stabilization can be achieved. The inventors have found that the present invention is effective and have completed the present invention. That is, the present invention relates to a method for producing stabilized sodium percarbonate, which is characterized in that sodium percarbonate contains at least one stabilizer of groups (A) and (B), which will be described later. In other words, the sodium percarbonate stabilized according to the present invention contains at least two sodium percarbonates selected from each group (A) and (B).
Contains more than one type of stabilizer. Group stabilizers (A) used in the present invention include aliphatic and aromatic amino acids or salts thereof having two or less carboxyl groups, or oligopeptides, polypeptides, or proteins of the amino acids; For example, glycine, glycylglycine, alanine, valine, serine, threonine, cystine, methionine, proline, aspartic acid, glutamic acid, lysine, taurine, anthranilic acid, aminobenzoic acid, albumin, brobulin, glutelin, prolamin, casein, gelatin, peptone. Proteins may be collectively called egg protein, milk protein, soybean protein, wheat protein, etc. based on their location names. The stabilizer (B) group includes polyphosphonic acid N(CH ₂ PO ₃ H ₂ ) ₃ , CH ₃ C(OH) (PO ₃ H ₂ ) ₂ , (H ₂ O ₃ PCH ₂ ) having the following structure. _2N ( _CH2 ) _nN ( _CH2PO3H2 ) _{2 (} n
=2~6), and its salts, such as aminotri(methylenephosphonic acid) (NTP), 1
-Hydroxyethylidene-1,1-diphosphonic acid (HEDP), ethylenediaminetetra (methylenephosphonic acid) (EDTP), hexaethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), and the like. Each of the above stabilizers should contain at least one stabilizer from each group.
The method of incorporating these into sodium percarbonate is to add them during the reaction step to produce sodium percarbonate from hydrogen peroxide and sodium carbonate, or to add them to sodium percarbonate in a secondary manner. This can be carried out by methods such as kneading or coating crystals or particles, or by using these methods in combination. Hydrogen peroxide and sodium carbonate produce sodium percarbonate with heat generation, but at this time, not only a part of the hydrogen peroxide is decomposed ineffectively and is lost, but in some cases, sufficient active oxygen may be lost. This may lead to a situation where it is not possible to obtain sodium percarbonate having the following properties. In order to avoid these problems and improve the yield of hydrogen peroxide, it is desirable that sodium percarbonate and hydrogen peroxide be sufficiently stabilized in the process of producing sodium percarbonate. At least one stabilizer component is added during the process of producing sodium percarbonate. In the present invention, (A) and
Group (B) stabilizers are 0.001 to 2.0% by weight and 0.01 to 2.0% by weight, respectively, based on the raw material sodium carbonate.
Weight percent, preferably 0.05 to 0.5 weight percent, and 0.1 to 1.0 weight percent. In the method of producing sodium percarbonate from the mother liquor by reaction crystallization, these stabilizers are added continuously or intermittently to the mother liquor together with sodium carbonate and hydrogen peroxide. In methods such as spray drying, in which the reaction is carried out apparently without the presence of a mother liquor, the stabilizer is incorporated into the sodium percarbonate by spraying the stabilizer at the same time as the raw materials. The sodium percarbonate thus produced is, if desired, left in a wet state or, after drying, further incorporated with a stabilizer by means such as kneading or coating, but these operations are usually carried out using a common mixer. This is carried out by using a washing machine, etc., or by spraying the stabilizer onto the crystals or particles and drying them. The stabilizing effect will not be impaired depending on the condition. Sodium percarbonate is usually used in the form of particles or granules that are easy to handle, so if necessary, it can be further processed by extrusion granulation, rolling granulation, stirring granulation,
Sodium percarbonate granules having the desired shape and physical properties are formed by known granulation methods such as crushing and granulation, tabletting, etc. At this time, common bonding methods that do not adversely affect the storage stability of sodium percarbonate are used. percarbonate having a desired active oxygen content using diluent such as sodium carbonate, sodium bicarbonate, sodium sulfate, etc. You can also get sodium. It is advantageous to add these together with the stabilizer during the process of kneading the stabilizer. The sodium percarbonate dried through such a process substantially contains stabilizers of groups (A) and (B) in a proportion of 0.001 to 2.0 weight percent and 0.01 to 2.0 weight percent, respectively. According to the present invention, for a long period of time, which has been difficult to obtain with conventional methods using known stabilizers,
Or, it maintains excellent storage stability even under high temperature and high humidity conditions, and not only can it produce sodium percarbonate, but also has great practical and industrial significance, such as not requiring any particular purification of raw materials during production. It is. Next, the present invention will be explained using Examples and Comparative Examples, but the present invention can be practiced without being limited thereto. Example 1 13.1% by weight of sodium carbonate, 2.5% by weight of hydrogen peroxide, 0.25% by weight of L-glutamic acid, HEDP (1% by weight)
-hydroxyethylidene-1,1-diphosphonic acid) using a mother liquor 150 having a composition of 0.2% by weight,
Sodium carbonate 27.0Kg/hr, 60 while stirring
Weight% hydrogen peroxide, 18.8/hr, sodium L-glutamate monohydrate 0.086Kg/hr, HEDP 0.56Kg/hr
Continuously feed into the reaction vessel at a rate of
The slurry was continuously drawn out with a residence time of 40 minutes while maintaining the temperature at 20°C, and after separating the cake by centrifugation, a continuous reaction was carried out for 4 hours by circulating the liquid. After drying, the storage stability of the obtained sodium percarbonate was measured, and the results showed excellent storage stability as shown in Table 1. Storage stability was determined by placing 2 g of the sample in a styrene container, leaving it open at 40°C and 80% relative humidity, and measuring the remaining available oxygen. Comparative Example 1 Mother liquor 150 having a composition of 13.1% by weight of sodium carbonate, 2.5% by weight of hydrogen peroxide, 0.2% by weight of EDTA (ethylenediaminetetraacetic acid), and 0.05% by weight of No. 3 sodium silicate was used, and sodium carbonate was added to this.
27.0Kg/hr, 60wt% hydrogen peroxide 18.8/hr,
EDTA0.56Kg/hr, No. 3 sodium silicate 0.045
The storage stability of sodium percarbonate obtained by carrying out a continuous reaction for 4 hours in the same manner as in Example 1, except that it was fed at a rate of 1 kg/hr, was as shown in Table 1. Comparative Example 2 The storage stability of sodium percarbonate obtained by carrying out a continuous reaction for 4 hours under the same conditions as in Example 1, except that HEDP in Example 1 was not used at all, was as shown in Table 1. It was hot. Comparative Example 3 Table 1 shows the storage stability of sodium percarbonate obtained by carrying out a continuous reaction for 4 hours under the same conditions as in Example 1, except that sodium L-glutamate in Example was not used. It was as shown.

[Table] Example 2 Using mother liquor 150 having a composition of 13.1% by weight of sodium carbonate and 2.5% by weight of hydrogen peroxide, to this was added 27.0 kg/hr of sodium carbonate and 60% by weight of hydrogen peroxide.
Continuous reaction was carried out while feeding at a rate of 18.8/hr, and the stabilizer shown below was further mixed with the sodium percarbonate crystals with a water content of 12% obtained by centrifugation using a sludge machine, and then dried. After that, the results shown in Tables 2 and 3 were obtained using these as samples. In addition, the effective oxygen residual rate is the value after 14 days after being left at 40°C and 80% relative humidity in an open state.

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Claims (1)

[Claims] 1. A method for producing stabilized sodium percarbonate, characterized in that sodium percarbonate contains at least one stabilizer of groups (A) and (B) shown below. . Group (A) Aliphatic and aromatic amino acids having up to 2 carboxyl groups, or salts thereof: or oligopeptides, polypeptides, or proteins of these amino acids, and denatured proteins. Group (B) Polyphosphonic acid having the following structure N(CH ₂ PO ₃ H ₂ ) ₃ , CH ₃ C(OH)(PO ₃ H ₂ ) ₂ , (H ₂ O ₃ PCH ₂ ) ₂ N(CH ₂ ) _o N(CH ₂ PO ₃ H ₂ ) ₂
(n=2-6), and its salts. 2. The method according to claim 1, wherein the stabilizer of group (A) is contained in the sodium percarbonate in an amount of 0.001 to 2.0% by weight based on the sodium percarbonate. 3. The method according to claim 1, wherein the stabilizer of group (B) is contained in the sodium percarbonate in an amount of 0.01 to 2.0% by weight based on the sodium percarbonate. 4. A patent claim in which, when sodium percarbonate is produced by reacting sodium carbonate and hydrogen peroxide in an aqueous solution, at least one stabilizer from groups (A) and (B) is added to the aqueous solution. The manufacturing method according to item 1. 5. A patent claim in which, when sodium carbonate and hydrogen peroxide are reacted in the absence of an aqueous solution to produce sodium percarbonate, at least one stabilizer from groups (A) and (B) is added during the reaction. The manufacturing method according to item 1.