JP4553080B2 - Sodium percarbonate particles with excellent stability and safety - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to sodium percarbonate particles having excellent storage stability and safety. The sodium percarbonate particles of the present invention are suitably used in household detergents containing a bleaching composition or a bleaching component.
[0002]
[Prior art]
Since sodium percarbonate has a high dissolution rate at a low temperature and can sufficiently exert a bleaching effect, demand for sodium percarbonate has been rapidly increasing in recent years as a blending component of a powdery detergent composition (household synthetic detergent). However, sodium percarbonate may be decomposed even at room temperature due to moisture in the cleaning composition or humidity and moisture in the air. Moreover, it may be decomposed by contact with zeolite, enzyme, etc. contained in the cleaning agent. In addition, sodium percarbonate itself is not a combustible material and is a safe compound by itself. However, contact or mixing with the combustible material for any reason during handling or storage can promote combustion under certain conditions. Therefore, various methods for obtaining sodium percarbonate having improved stability and safety by preventing or suppressing decomposition of sodium percarbonate have been proposed.
[0003]
For example, a method of coating with an alkaline earth metal salt (Japanese Patent Publication No. 57-7081), a method of coating sodium percarbonate particles with sodium carbonate and sodium bicarbonate (Japanese Patent Publication No. 58-24361), borate and silicic acid Method of coating with alkali metal salt (Japanese Patent Laid-Open No. 59-193999), alkali metal or alkaline earth metal sulfate, nitrate or silicate, and compounds such as monocarboxylic acid or dicarboxylic acid having 4 or more carbon atoms A method for stabilizing sodium percarbonate containing benzene has been proposed (Japanese Patent Laid-Open No. 3-40909).
[0004]
Further, as a method for reducing the risk of combustion when sodium percarbonate and combustible materials are mixed, there is a method of adding a risk inhibitor (JP-A-2-296705, JP-A-3-187905). JP-A-3-28111, JP-A-3-28112, etc.). However, in the method of blending a large amount of the risk inhibitor, there is a problem that the stability of sodium percarbonate when blended with a detergent or the like is not sufficient and the dissolution rate becomes small.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to solve the above-mentioned problems in the prior art, and to provide sodium percarbonate that exhibits high stability even when blended with a detergent and is less likely to burn even when mixed with combustible materials. There is.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have determined that the surface of the sodium percarbonate particles is (NH) -NH-C (= O) -NH- or -NH-C (= A compound having at least one group represented by NH) -NH- and (B) at least one compound selected from the group consisting of alkali metal bicarbonates, alkali carbonates and sulfates, The inventors have found that sodium percarbonate particles in which the problem has been solved can be obtained, and have reached the present invention.
[0007]
That is, the present invention provides at least one group represented by (-)-NH-C (= O) -NH- or -NH-C (= NH) -NH- in the molecule (A) in the sodium percarbonate particles. 0.1 to 2.5% by weight of the compound and (B) 5 to 20% by weight of at least one compound selected from the group consisting of alkali metal bicarbonate, alkali metal carbonate and alkali metal sulfate It is related with the sodium percarbonate particle | grains characterized by these.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Among the compounds (A) covering sodium percarbonate of the present invention, compounds having a group represented by —NH—C (═O) —NH— in the molecule include urea, semicarbazide, semicarbazide hydrochloride, uracil, 5 -Aminouracil, 5-nitrouracil, 5-mercaptouracil, hydantoin, 5,5-dimethylhydantoin, parabanic acid, barbituric acid, thymine, alloxan, 2-imidazolidinone, xanthine, biuret, urazole, uric acid, isocyanuric acid, Examples include purpuric acid, murexide, and allantoin.
[0009]
Examples of the compound (A) having a group represented by —NH—C (═NH) —NH— in the molecule include dicyandiamide, guanidine hydrochloride, guanidine nitrate, guanidine carbonate, guanidine phosphate, guanidine sulfamate, Examples thereof include aminoguanidine hydrochloride, aminoguanidine bicarbonate, aminoguanidine sulfate, and guanylthiourea.
[0010]
Among the compounds (A), as a compound having both a group represented by —NH—C (═O) —NH— and a group represented by —NH—C (═NH) —NH— in the molecule, Examples thereof include guanyl urea phosphate, guanyl urea sulfate, guanyl urea nitrate, ammelide, ammelin and the like. Of these, urea or dicyandiamide is preferred because of its availability and high effect.
[0011]
Examples of the alkali metal bicarbonate salt of compound (B) include sodium bicarbonate and potassium bicarbonate. Examples of the alkali metal carbonate include sodium carbonate, potassium carbonate, and lithium carbonate. Examples of the alkali metal sulfate include sodium sulfate, potassium sulfate, and lithium sulfate.
[0012]
In this invention, in addition to a compound (A) and a compound (B), the sodium percarbonate particle | grains which were further excellent in stability can be obtained by further coat | covering (C) magnesium sulfate to sodium percarbonate particle | grains.
[0013]
The coating amount of the compound of group (A) is 0.1 to 2.5% by weight, preferably 0.2 to 1% by weight, based on sodium percarbonate. The coating amount of the compound of group (B) is 5 to 20% by weight with respect to sodium percarbonate. Moreover, the coating amount of (C) magnesium sulfate is 1 to 5% by weight with respect to sodium percarbonate.
[0014]
If the coating amount is less than the above range, the desired stability or risk suppressing effect cannot be obtained, and if the coating amount is more than the above range, the solubility is lowered and the effective oxygen concentration of the sodium percarbonate particles is lowered. For this reason, it is not preferable in terms of economy.
[0015]
The coated sodium percarbonate particles have a particle size of 200 to 2000 μm, preferably 400 to 1000 μm. When the particle size of the sodium percarbonate particles is too small, the surface area per unit weight is increased, and the particle surface is not uniformly coated and the stability is lowered. On the other hand, if the particle size is too large, the fluidity of the particles during the coating operation is deteriorated, and uniform coating becomes difficult and the particles are likely to aggregate.
[0016]
The sodium percarbonate particles of the present invention are, for example, granulated and dried by adding a binder or the like to wet sodium percarbonate crystals, and the obtained particles are divided into groups (A) and (B), or further (C). Obtained by coating a group of compounds. The coating method is generally a method in which a compound is made into a solution with water or an organic solvent, sprayed onto flowing sodium percarbonate particles, and dried. A solution containing all of the coating agent may be prepared and sprayed and dried, or a plurality of solutions may be prepared for each coating agent and may be sprayed and dried sequentially or simultaneously. Further, a stabilizer and a granulating binder, which are general additives for sodium percarbonate, can be used in combination.
[0017]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[0018]
Reference example 1
Sodium carbonate and hydrogen peroxide were reacted in an aqueous solution, and the produced crystals were separated by a centrifuge and dehydrated to obtain wet sodium percarbonate. A binder is added to wet sodium percarbonate, water is further added to adjust the water content to 10% by weight, extrusion granulation is performed with a granulator equipped with a screen having a hole diameter of 1.0 mm, and then dried. Uncoated sodium percarbonate having an average particle size of 800 μm was obtained. 300 g of the obtained uncoated sodium percarbonate was coated using a fluidized drying coating apparatus (Palvis coating apparatus manufactured by Yamato Scientific Co., Ltd.). The coating was performed by spraying 300 g of an aqueous solution containing 1.0% by weight of urea and 15% by weight of sodium sulfate from the attached spray nozzle while fluidly drying sodium percarbonate by introducing heated air from a perforated plate. This was done by continuing to dry for a minute.
[0019]
A blending test and combustion test of the obtained sodium percarbonate particles with a hygroscopic zeolite were carried out. The test results are shown in Table 1.
<Combination test with hygroscopic zeolite>
Place 1 g of synthetic zeolite 4A powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.) and 1 g of sample absorbed in a 30 ° C., 80% relative humidity atmosphere for at least 24 hours in a plastic bag with a chuck (thickness 40 μm) and shake well. mix. This is left for 4 days in an atmosphere of 30 ° C. and 80% relative humidity, and the effective oxygen concentration of the sample before and after being left is determined by titration with sodium thiosulfate, and the effective oxygen residual rate is calculated by the following equation to obtain the stability. .
Effective oxygen residual rate (%) = (effective oxygen concentration after test (%) / effective oxygen concentration before test (%)) × 100
<Combustion test>
The sample that passed through a sieve having an opening of 1180 μm was stored in a desiccator containing dry silica gel at a temperature of 20 ± 5 ° C. for 24 hours or more. Also, the Japanese cedar sapwood powder that did not pass through a 250 μm sieve sieve and passed through a 500 μm sieve was dried at 105 ° C. for 4 hours, and then stored in a desiccator containing dry silica gel for 24 hours or more. 24g of preserved sample and 6g of preserved wood flour are mixed, put into a conical cup with a ratio of height to base diameter of 1: 1.75, and this is laid down on an insulating plate to make a conical deposit, Leave in an atmosphere of temperature 20 ± 5 ° C. and humidity 50 ± 10% for 1 hour. Thereafter, an annular nichrome wire heated to 1000 ° C. is brought into contact with the base of the deposit, and the ignition and combustion states are observed. Combustion occurs when a wood powder compound is ignited and the flame continues to the end. The test is performed 10 times per sample and the number of combustion is compared.
[0020]
Examples 1-2, Reference Examples 2-7
The same procedure as in Reference Example 1 was carried out by changing the combination of coating agents. Table 1 shows the type and coverage of the coating agent and the test results.
[0021]
Comparative Examples 1-3
The same procedure as in Reference Example 1 was carried out by changing the combination of coating agents. Table 1 shows the type and coverage of the coating agent and the test results.
[0022]
Comparative Example 4
300 g of uncoated sodium percarbonate prepared in the same manner as in Reference Example 1 , 3 g of urea (1% by weight based on uncoated sodium percarbonate), 45 g (15% by weight) of sodium sulfate and 4.5 g (1.5% by weight) of magnesium sulfate %) Was mixed well to obtain a sodium percarbonate composition. When the blending test and combustion test of the obtained sodium percarbonate particles with a hygroscopic zeolite were carried out, the zeolite blending stability was 65% and the number of combustions was 8/10.
[0023]
【The invention's effect】
According to the present invention, it is possible to obtain sodium percarbonate having high stability even when blended with a detergent, and having a low risk even when mixed with a combustible material.
[0024]
[Table 1]

Claims (2)

The sodium percarbonate particles are coated with (A) urea or dicyandiamide 0.2 to 1 % by weight, (B) sodium carbonate or sodium sulfate 5 to 15 % by weight , and (C) magnesium sulfate 1% by weight. Characteristic sodium percarbonate particles.   The sodium percarbonate particles according to claim 1, wherein the particle size of the sodium percarbonate particles is 200 to 2000 μm.