JP4506962B2 - Sodium percarbonate particles with excellent foam solubility - Google Patents

Description

  The present invention relates to a method for producing sodium percarbonate particles having excellent foam solubility in water and being less crushed and worn during handling. The sodium percarbonate particles of the present invention are suitably used as a bleaching composition.

  Sodium percarbonate has little influence on the environment because its decomposition products are mainly water and oxygen, and is widely used as an oxygen bleach. Although sodium percarbonate has good solubility in hot water, it is relatively insoluble in low-temperature water. In addition, since the concentration of the bleach component is partially increased by adhering to colored clothes, etc., in order not to cause decolorization or decrease in fiber strength, there is a need for improved solubility and no undissolved residue. Yes. In addition, since sodium percarbonate is handled in a powder form, it is also required to have less dusting when used.

  One method for improving the solubility of sodium percarbonate at low temperatures is to heat-treat sodium percarbonate to give foaming properties (see Patent Document 1). However, in order to obtain a desired solubility only by imparting foamability by heating, heat treatment for a long time at high temperature is required, and during this time, decomposition of effective oxygen advances and is not an effective means. Moreover, the particle strength of sodium percarbonate is weakened by the heat treatment, and a large amount of fine powder is generated due to crushing and wear during handling, resulting in a problem of increased dusting.

A method has also been proposed in which nonionic surfactants such as ethylene oxide adducts of higher alcohols are added to increase floatation and heat treatment is performed to improve solubility, but the particle strength becomes weaker and crushing and abrasion occur. The problem of increased powder generation due to the generation of fine powder due to is not solved (see Patent Document 2). In addition, a method is disclosed in which sodium percarbonate particles are coated with a metal salt and foamed and dissolved when dissolved in water by setting the treatment temperature to 95 ° C to 105 ° C, but the solubility is insufficient. Further improvement is required (see Patent Document 3).
JP 54-43199 A Japanese Patent Publication No.62-14485 Japanese Patent Laid-Open No. 10-194710

  An object of the present invention is to solve the above-described problems in the prior art, and to provide sodium percarbonate particles that are excellent in foam solubility when dissolved in water and are less crushed and worn during handling.

  The present inventors have intensively studied to solve such problems, and completed the present invention. That is, the present invention is characterized in that sodium percarbonate particles are coated with 0.1 to 15% by weight of a water-soluble polymer and heat-treated at 50 ° C. to 120 ° C. The present invention relates to a method for producing sodium percarbonate particles with less crushing and wear.

  The sodium percarbonate particles of the present invention foam when dissolved in water and quickly dissolve while floating in water. In addition, the amount of undissolved residue after sinking to the bottom is extremely small, and the solubility in a state where there is no stirring or almost no stirring is excellent. In addition, the product of the present invention has a high particle strength, less generation of fine powder due to crushing and abrasion, and less dusting during handling.

  The present invention will be described in more detail. Sodium percarbonate reacts with sodium carbonate and hydrogen peroxide in water, separates the precipitated crystals with a centrifugal separator or the like, and granulates using the obtained sodium percarbonate crystals. Examples of the granulation include, but are not limited to, agglomeration granulation using a kneading granulator and extrusion granulation using an extrusion granulator having a screen. An inorganic salt can be added as a diluent for reducing the supporting property of sodium percarbonate during granulation. Specific examples include sodium carbonate, potassium carbonate, sodium bicarbonate, sodium sulfate and the like. Various types of binders can be used during granulation. Examples of inorganic binders include silicates and magnesium salts, and examples of organic binders include polyvinyl alcohol and carboxymethyl cellulose, but are not limited thereto.

  The granulated sodium percarbonate particles are dried and then coated with a water-soluble polymer. Examples of the water-soluble polymer in this case include polyethylene glycol, polyvinyl alcohol, polyacrylic acid, and sodium polyacrylate. Among them, polyethylene glycol is preferable. Polyethylene glycol having a molecular weight of 1000 to 20000, preferably 2000 to 20000 is suitable. Two or more water-soluble polymers may be mixed and used.

  For coating, a method of flowing sodium percarbonate particles with heated air and spraying a water-soluble polymer with an aqueous solution is common but not limited. It is also possible to coat the sodium percarbonate particles coated with an inorganic salt with a water-soluble polymer. Examples of inorganic salts in this case include carbonates, bicarbonates, sulfates, silicates, and borates. It is also possible to coat by mixing a water-soluble polymer and an inorganic salt. The amount of the water-soluble polymer is 0.1 to 15% by weight, preferably 0.5 to 10% by weight, based on sodium percarbonate. If the coating amount is 0.1% by weight or less, the desired floating property cannot be obtained, and if the coating amount exceeds 15% by weight, no improvement is seen in the particle strength, and further increase in the amount is not economical.

  After coating with sodium percarbonate particles, heat treatment is performed. The heating temperature is 50 ° C to 120 ° C, preferably 95 ° C to 120 ° C, more preferably 100 ° C to 105 ° C. Immediately after heating, in order to suppress decomposition of available oxygen. Examples of the cooling method include, but are not limited to, a method using air as it is or dehumidifying, a method using nitrogen, and the like. The temperature after cooling is preferably 40 ° C. or lower.

  The heat-treated sodium percarbonate particles are preferably screened to make 2,000 μm or more large particles 1% by weight or less and 180 μm or less fine particles 3% by weight or less. If there are many large particles exceeding 2,000 μm, the particles are easily disintegrated and the flying property is remarkably lowered. On the other hand, when there are many fine powders smaller than 180 micrometers, powdering will increase.

  Moreover, the sodium percarbonate particle | grains obtained by the method of this invention can add components, such as surfactant, an activator, a stabilizer, and a fragrance | flavor, and can be used as the bleaching composition for clothes. In addition, it can be used for various applications such as kitchen bleach, bath tub cleaner, drain pipe cleaner, and washing tub cleaner.

  Next, the method of the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

Example 1
Sodium carbonate and hydrogen peroxide were reacted in an aqueous solution, and the produced sodium percarbonate crystals were separated by a centrifuge and dehydrated to obtain wet sodium percarbonate containing 10% by weight of water. To sodium percarbonate in a wet state, sodium bicarbonate made by Tosoh was added to sodium percarbonate in an amount of 20% by weight on a dry basis, 0.2% by weight magnesium sulfate and 0.25% by weight sodium silicate as a binder, and water. Was added to adjust the water content to 11%. Next, granulation was performed in the order of a kneading dryer and a granulator, followed by drying at 70 ° C. for 2 hours to obtain sodium percarbonate particles having an average particle diameter of 500 μm.

  Using 300 g of the obtained sodium percarbonate particles, 150 g of an aqueous solution containing 10% by weight of polyethylene glycol having an average molecular weight of 6000 while flowing sodium percarbonate with heated air using a fluid dryer (Yamato Kagaku Co., Ltd. Parvis mini bed). Were spray coated. After coating, the heated air was kept at a temperature of 100 ° C. and heated for 90 minutes while flowing. After cooling the heated product, large particles and small particles were removed using a vibrating sieve provided with an upper mesh opening of 1400 μm and a lower mesh opening of 250 μm. About the obtained sodium percarbonate particle | grains, the floating property at the time of throwing into water and the disintegration property defined by Formula (1) were derived. The measurement results are shown in Table 1.

<Method of measuring disintegration>
Put 100 g of sample with a particle size of 180 μm or less with a sieve into a 500 ml polyethylene jar and shake for 10 minutes with a shaker. The amount was measured.

<Floatability measurement method>
Place 1000 g of water at 10 ° C. into a 1000 ml beaker, put 1 g of sample in the center of the beaker, visually determine the amount of sodium percarbonate particles that rise, and rank A to E.

Example 2
The same operation as in Example 1 was performed except that the amount of the 10 wt% polyethylene glycol aqueous solution to be coated was changed to 60 g. The measurement results are shown in Table 1.

Example 3
The same operation as in Example 1 was performed except that the average molecular weight of polyethylene glycol to be coated was 2000. The measurement results are shown in Table 1.

Example 4
The same operation as in Example 1 was performed except that the average molecular weight of polyethylene glycol to be coated was 20000. The measurement results are shown in Table 1.

Example 5
The same procedure as in Example 1 was performed except that heating was performed for 180 minutes while keeping the temperature of the heated air after coating at 85 ° C. and flowing. The measurement results are shown in Table 1.

Comparative Example 1
The same procedure as in Example 1 was performed except that polyethylene glycol was not coated. The measurement results are shown in Table 1.

Comparative Example 2
The same operation as in Example 1 was performed except that heating was not performed. The measurement results are shown in Table 1.

Comparative Example 3
The same procedure as in Example 1 was performed except that heating was performed for 180 minutes while keeping the temperature of the heated air after coating at 40 ° C. and flowing. The measurement results are shown in Table 1.

Comparative Example 4
It was carried out in the same manner as in Example 1 except that heating was carried out for 20 minutes while keeping the temperature of heated air after coating at 125 ° C. and flowing. The measurement results are shown in Table 1.

Comparative Example 5
The same operation as in Example 1 was performed except that the average molecular weight of the polyethylene glycol to be coated was 600. The measurement results are shown in Table 1.

Comparative Example 6
Although the average molecular weight of the polyethylene glycol to be coated was 500,000, the solubility in water was small and the coating could not be performed.

Claims (1)

Sodium percarbonate particles are coated with 0.1 to 15% by weight of polyethylene glycol having a molecular weight of 1000 to 20000 and heat-treated at 50 ° C to 120 ° C. A method for producing sodium percarbonate particles with less crushing and wear.