JPS6141350B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for pulverizing an aqueous slurry containing higher alkyl sulfates. Higher alkyl sulfates are one of the typical anionic surfactants and are widely used in kitchen detergents and shampoos in combination with other surfactants and/or builders, as well as powdered shampoos and cleaning agents. There are many cases in which higher alkyl sulfates are used in the form of powder as an intermediate raw material in producing foaming agents and the like. Generally, powders containing surfactants have a problem of losing their smoothness or solidifying due to moisture absorption, and powders containing higher alkyl sulfates are no exception to this problem. The present invention provides a method for obtaining powder or granular material containing higher alkyl sulfate as a main component with good powder physical properties, relatively high bulk density, and high particle strength. As is well known, powders containing higher alkyl sulfates as a main component are produced by preparing an aqueous slurry containing higher alkyl sulfates and other additives, and spray-drying this slurry. When producing powder by spray drying an aqueous slurry of not only higher alkyl sulfates, the bulk density and particle strength of the resulting powder vary depending on the type of spray drying used and the drying conditions. In general, it depends on the water content of the aqueous slurry subjected to spray drying, and as the water content decreases, the bulk density and particle strength of the resulting powder tend to increase. However, as the water content decreases, the viscosity of the aqueous slurry increases rapidly;
This is difficult to spray dry, and in fact as the water content of the aqueous slurry falls below 60-70%, the spray drying operation becomes extremely difficult. Under these circumstances, many attempts have been made to reduce the water content of an aqueous slurry without increasing its viscosity when obtaining powder or granules by spray drying. The method of adding a lower alcohol such as methanol is a typical example of such a device, but there are also methods of adding a lower fatty acid alkali salt or lower fatty acid polyalkylene glycol ester to the soap slurry (Japanese Patent Publication No. 36-23860), A method of intervening an inorganic salt in a linear alkylbenzene sulfonate slurry (Japanese Patent Publication No. 11171/1971), a method of adding polyethylene glycol to a higher alcohol sulfate slurry, etc. (Japanese Patent Application Laid-open No. 116383/1983),
Method of adding excess alkali
80285) or, conversely, a method using a partially neutralized anionic activator (Japanese Patent Application Laid-open No. 80309/1983). However, the addition of lower alcohols is not only uneconomical since the lower alcohols volatilize during spray drying, but is also undesirable in that it is accompanied by the risk of fire or explosion, and is also a cause of air pollution. On the other hand, other methods that use specific additives require the use of large amounts of additives to achieve the desired effect, and the additives remain in the powder or granules, so The drawback is that the applications of the resulting powder and granules are limited depending on the type of additive. The present inventors aimed to improve the powder physical properties of powder obtained by spray drying an aqueous slurry containing higher alkyl sulfates as a main component, and to increase the bulk density and particle strength of higher alkyl sulfates. As a result of intensive research on the physical properties of salt water slurry, we found that the viscosity of the slurry increases rapidly when the solid content concentration is 40% by weight or more (therefore, the water content is 60% by weight or less), and at 50% by weight it becomes a gel. However, it was found that when the solid content concentration was further increased, the viscosity decreased once and then increased again. and solid content concentration 70
It was determined that there is a small viscosity minimum in the region of around % by weight. Therefore, by spray-drying an aqueous slurry having this minimum viscosity value, it is possible to obtain a powder mainly composed of higher alkyl sulfate, which has good powder physical properties, relatively large bulk density, and high particle strength. can. The present invention was completed based on these findings, and its basic feature is that an aqueous slurry containing higher alkyl sulfates as the main solid content is prepared at a solid content of 60 to 80% by weight. and maintain the temperature at 50 to 120°C, and spray dry this aqueous slurry in a conventional manner. The aqueous slurry of the present invention has a higher alkyl sulfate as the main solid content, and the higher alkyl sulfate is represented by the following general formula. RSO ₄ M Here, R represents a straight chain or branched alkyl group or alkenyl group having 8 to 18 carbon atoms, preferably 10 to 16 carbon atoms, and M represents an alkali metal, preferably Na. The above-mentioned higher alkyl sulfates are, for example, natural higher alcohols from matcha whale oil, reduced alcohols from natural fatty acids such as coconut fatty acids and beef tallow fatty acids, wax cracking, or oxo-synthesis of α-olefins obtained by polymerization of ethylene. It can be produced by using higher synthetic alcohols as raw materials and sulfating these raw material alcohols with a thin film using SO ₃ or sulfating them with chlorosulfonic acid. The aqueous slurry of the present invention may contain builders such as alkali metal salts of silicic acid, carbonic acid, sulfuric acid, phosphoric acid, and citric acid, recontamination preventive agents such as CMC (carboxymethylcellulose), BHT (butylated hydroxytoluene), and BHA. A small amount of an antioxidant such as (butylhydroxyanisole) or an additive such as MgSO ₄ may be added. Also, sulfated by-product salt,
A small amount of Glauber's salt etc. may be included. However, the amount of these optional components added should be 10% by weight or less of the solid content of the slurry, making it possible to maintain the amount of higher alkyl sulfates in the solid content at 90% by weight or more. As mentioned above, the aqueous slurry of the present invention is required to have a solid content concentration in the range of 60 to 80% by weight, preferably 70 to 78% by weight;
If the slurry decreases to 60% by weight or less (excluding 40% by weight or less) or increases to 80% by weight or more, the aqueous slurry becomes gelled and spray drying becomes difficult, making spray drying impossible. However, it is not possible to obtain high-quality powder or granules. The aqueous slurry temperature during spray drying is 50~120℃,
Preferably, it can be maintained at 70 to 110°C,
If the temperature is below 50°C, the viscosity of the slurry will increase rapidly, making spray drying difficult, or even if spray drying is possible, the powder properties will be poor. If the temperature exceeds 120°C, the alkyl sulfate in the slurry will decompose, which is not preferable. The spray drying of the present invention can be carried out using conventional spray drying equipment and under conventional spray drying conditions. As is clear from the above detailed description, the present invention involves spray drying an aqueous slurry containing higher alkyl sulfate as a main component in a state where the solid content concentration is high. It has good physical properties, especially its bulk density and particle strength. Therefore, the powdered material exhibits good storage stability. Furthermore, the aqueous slurry of the present invention has a relatively low viscosity despite its high solid content concentration, and therefore has high efficiency when spray-dried. Therefore, the present invention also promises cost savings in the production of powder and granular materials. Example 1 A mixture of linear alkyl sodium sulfates with different chain lengths (C ₁₀ ; 20%, C ₁₂ ; 65%, C ₁₄ ; 15
%) and a small amount of sodium sulfate to prepare aqueous slurries with different solid content concentrations, and then spray-dry this aqueous slurry under the following conditions to evaluate the powder physical properties and drying efficiency of the resulting powder. compared. The results are shown in Table 1. Spray drying conditions: Equipment Disk type spray dryer Hot air temperature Approximately 150 to 200℃ Hot air direction Parallel flow

[Table] As is clear from Table 1, experiments according to the present invention
Only in the case of Nos. 4 and 5, powder with good powder physical properties can be obtained and the drying efficiency is also high. Example 2 As a higher alkyl sulfate, a mixture of linear alkyl sodium sulfates with different chain lengths (however,
C ₁₂ ; 65%, C ₁₄ ; 25%, C ₁₆ ; 10%),
An experiment was conducted in the same manner as in Example 1, except that a nozzle-type spray dryer was used as the spray dryer, and Table 2 was obtained.
The results shown are obtained.

[Table] Example 3 Various additives were added to the linear alkyl sodium sulfate and sodium sulfate used in Example 1,
Aqueous slurries having different solid content concentrations were prepared, and the slurries were spray-dried under the same conditions as in Example 1, and the powder physical properties of the resulting powders were compared. However, a nozzle type spray dryer was used as the drying device. The results are shown in Table 3.

【table】

[Table] As is clear from the results shown in Table 3, even if any solid content other than higher alkyl sulfate is added to the aqueous slurry, the amount will be less than 10% of the total solid content,
In addition, as long as the aqueous slurry is spray-dried while satisfying the requirements of the present invention, powder and granules with excellent powder physical properties can be obtained.

Claims (1)

[Claims] 1. A higher alkyl sulfate represented by the general formula RSO ₄ M (where R represents a linear or branched alkyl group or alkenyl group having 8 to 18 carbon atoms, and M represents an alkali metal). When spray drying and pulverizing the aqueous slurry containing the main solid content, the solid content concentration of the aqueous slurry is adjusted to 60 to 80% by weight, and the temperature is adjusted to 50 to 120°C. A method for pulverizing the aqueous slurry, which comprises holding and spray-drying the aqueous slurry. 2. The method according to claim 1, wherein the solid content of the higher alkyl sulfate in the aqueous slurry is 90% by weight or more. 3. The method according to claim 1, wherein R in the general formula RSO ₄ M is a straight chain or branched alkyl group or alkenyl group having 10 to 16 carbon atoms. 4. The method according to claim 1, wherein M in the general formula RSO ₄ M is sodium. 5. The method according to claim 1, wherein the temperature of the aqueous slurry is maintained at 70 to 110°C.