JP5034682B2 - Method for producing particulate metal soap - Google Patents

Description

The present invention relates to a method for producing a fine particle metal soap mainly composed of a metal stearate soap, and in particular, does not require a special operation or reaction apparatus, using a general apparatus, by a general metathesis method, The present invention relates to a method for easily and efficiently producing a fine particle metal soap mainly composed of a metal stearate having a mean particle size of 1.0 μm or less and particles having a particle size larger than 4 μm of 5% by weight or less.

  As an industrial method for producing metal soaps, fatty acids are saponified with caustic soda or caustic potash to obtain alkaline soaps, which are then reacted with metal salts to obtain metal soaps, and fatty acids are converted into metal oxides. The direct method of obtaining metal soap by reacting with or hydroxide is most common. Among these methods, the metathesis method gives a product with a smaller primary particle size compared to the direct method. On the other hand, depending on the drying temperature, the primary particles cause strong secondary aggregation, and the average particle size is several. Only products ranging from μm to over a dozen μm can be obtained. According to the direct method, the product obtained has a large primary particle size distribution width and a large primary particle size.

  Metal soap is used in various industrial fields as an additive for the purpose of preventing adhesion of toner, cosmetics, pigments, fibers, etc., imparting lubricity, imparting dispersion, etc. In recent years, such as toners, cosmetics, pigments, etc. As fine particles have been made, there is an increasing demand for fine particles of metal soap as an additive in those applications.

  In order to make metal soap into fine particles, as a representative method that has been known in the past, a dry product of metal soap obtained by a metathesis method or a direct method is dispersed in dry pulverization with high-pressure air or silicone oil. A method of wet grinding with a bead mill is known. However, according to dry pulverization, it is generally difficult to make fine particles to an average particle diameter of 1 μm or less. On the other hand, according to wet pulverization, fine particle formation is possible to some extent, but the average particle diameter is 1 μm or less. There is a problem that it takes a long time to make fine particles.

  Therefore, the aqueous solution of fatty acid alkaline soap and the metal salt are separately supplied directly to the rotor of the mixer, and both are instantaneously mixed, and then the reaction product is immediately discharged from the mixer. Although the method to perform is also known (refer patent document 1), the obtained metal soap still has an average particle diameter of 2 μm or more, and does not sufficiently meet the demand for fine particles.

Moreover, the crystal transition start of the metal soap which produces | generates 0.001-20 weight% aqueous solution and inorganic metal salt 0.001-20 weight% aqueous solution or dispersion of C4-C30 fatty acid alkali metal salt or ammonium salt There is also known a method in which a metal soap slurry is obtained by mixing at a temperature lower than that, and then dried at a temperature lower than the crystal transition start temperature of the metal soap to obtain metal soap fine particles (see Patent Document 2). . According to this method, it is considered that the secondary aggregation due to drying is reduced by setting the drying temperature of the primary particles of the fine metal soap to be equal to or lower than the crystal transition start temperature of the metal soap. Although the following metal soaps can be obtained, drying takes a long time, the production efficiency is inferior, and the obtained metal soap particles are still agglomerated, so the dispersibility has not been improved so much. .
JP-A-1-299247 JP-A-11-323396

  The present invention has been made to solve the above-described problems in metal soap micronization, and does not require any special operation or reaction apparatus. Another object of the present invention is to provide a method for easily and efficiently producing a fine particle metal soap mainly composed of a metal stearate soap. Furthermore, this invention aims at providing the fine particle metal soap obtained by such a method.

  According to the present invention, an alkaline soap of stearic acid and an alkaline soap of a second linear saturated fatty acid having a melting point of 70 ° C. or more and optionally having a hydroxyl group are reacted with a metal salt in water. The mixture of the resulting stearic acid metal soap and the second fatty acid metal soap is separated from water, dried at a temperature above the crystal transition temperature of the stearic acid metal soap, and then pulverized. There is provided a method for producing a fine particle metal soap having an average particle size of 1.0 μm or less and 5% by weight or less of particles having a particle size larger than 4 μm.

  According to the present invention, at least one selected from behenic acid and 12-hydroxystearic acid is preferably used as the second fatty acid. The second fatty acid is preferably used in a range of 2 to 20% by weight based on the total amount of stearic acid and the second fatty acid.

  According to the method of the present invention, fine particles mainly composed of a metal stearate soap having an average particle size of 1.0 μm or less and a maximum particle size of 4 μm or less are obtained by a general metathesis method without requiring any special operation or reaction apparatus. Metal soap can be obtained easily and efficiently.

  The method for producing a fine particle metal soap according to the present invention comprises an alkaline soap of stearic acid and an alkaline soap of a second straight-chain saturated fatty acid having a melting point of 70 ° C. or higher and optionally having a hydroxyl group in water. And a mixture of the obtained stearic acid metal soap and the second fatty acid metal soap is separated and dried at a temperature equal to or higher than the crystal transition temperature of the stearic acid metal soap. By pulverizing, a fine particle metal soap having an average particle size of 1.0 μm or less and particles having a particle size larger than 4 μm is 5% by weight or less is obtained.

  Stearic acid is a name that refers to a straight-chain saturated fatty acid having 18 carbon atoms in chemical terms, but contains animal oils such as beef tallow and lard, and vegetable oils such as palm oil. A product obtained by hydrogenating an unsaturated fatty acid is generally referred to as industrial stearic acid. The main components of industrial stearic acid obtained by hydrogenating unsaturated fatty acids of such animal and vegetable oils include palmitic acid, which is a linear saturated fatty acid having 16 carbon atoms, in addition to stearic acid, which is a linear saturated fatty acid having 18 carbon atoms. A small amount of myristic acid, which is a linear saturated fatty acid having 14 carbon atoms, is included. In the present invention, when referred to as stearic acid, not only linear saturated fatty acids having 18 carbon atoms but also industrial stearic acid including palmitic acid and myristic acid as described above are included. Examples of the alkaline soap of stearic acid include sodium soap, potassium soap, and ammonium soap.

  In the present invention, the second fatty acid is a straight-chain saturated fatty acid having a melting point of 70 ° C. or higher and may have a hydroxyl group, and examples thereof include arachidic acid, behenic acid, lignoceric acid, and serotic acid. C20-30 linear saturated fatty acids such as montanic acid and melissic acid, and 12-hydroxystearic acid are preferably used. Among them, behenic acid or 12-hydroxystearic acid is preferably used. These 2nd fatty acids may be used independently and may use 2 or more types together.

  In the present invention, as in the case of stearic acid, the second fatty acid may be generally available for industrial use. Such industrial second fatty acid is, for example, industrial behenic acid. If so, other fatty acids may be contained in addition to behenic acid. However, even when the industrial second fatty acid is used, the melting point must be 70 ° C. or higher.

  According to the present invention, for example, sodium soap, potassium soap, ammonium soap or the like is used as the second fatty acid alkaline soap, like the stearic acid alkaline soap. The alkaline component (alkali metal component or ammonium component) in the second fatty acid alkaline soap is not necessarily the same as the alkaline component in the stearic acid alkaline soap, but is preferably the same.

  In the present invention, the second fatty acid is used in the range of 2 to 20% by weight, preferably 5 to 15% by weight, based on the total amount of stearic acid and the second fatty acid. When the ratio of the second fatty acid is less than 2% by weight, the average particle diameter is 1.0 μm even when the obtained metal soap is dried and ground, including the place where the second fatty acid is not used. The following fine particle metal soap cannot be obtained, and the fine particle metal soap in which the proportion of particles having a particle diameter of 4 μm or less is 5% by weight or less cannot be obtained. When the proportion of the second fatty acid is more than 20% by weight, the obtained metal soap may impair the desirable properties as a metal stearate soap.

  In the present invention, the metal species constituting the fine particle metal soap is not particularly limited and includes lithium, calcium, barium, magnesium, zinc, aluminum, copper, iron, lead, cobalt, nickel, and the like, and two or more metals The seeds may be mixed. Accordingly, in the present invention, the metal salt to be reacted with the alkaline soap of stearic acid and the alkaline soap of the second fatty acid is not particularly limited, and examples thereof include zinc sulfate, calcium chloride, magnesium sulfate and the like. Can do.

  Production of the fine particle metal soap by the method of the present invention is carried out according to a conventional metathesis method known in the art. Accordingly, there is no need in the reaction operation, reaction conditions, reaction apparatus, etc., for example, an aqueous solution of an alkaline soap containing an alkaline soap of stearic acid and an alkaline soap of a second fatty acid, and the metal as described above. An aqueous salt solution may be prepared, mixed, and reacted. The aqueous solution of the alkaline soap is usually obtained by suspending stearic acid and a second fatty acid in warm water, and adding, for example, a caustic soda aqueous solution to the mixture, stirring, the alkaline soap of stearic acid and the alkali metal of the second fatty acid An aqueous solution containing soap is prepared, and this is used as an aqueous solution of alkaline soap for the subsequent reaction with the metal salt.

  Here, in the present invention, the concentration of the alkali soap is usually in the range of 0.1 to 15% by weight, and preferably in the range of 1 to 10% by weight. On the other hand, the concentration of the aqueous metal salt solution is usually in the range of 0.1 to 20% by weight, and preferably in the range of 0.1 to 10% by weight. The reaction temperature at the time of mixing and reacting the alkaline soap and metal salt aqueous solution is usually in the range of 20 to 95 ° C, preferably in the range of 35 to 80 ° C, and most preferably 50 to 70 ° C. Range.

  In the present invention, when mixing the aqueous solution of the alkali soap and the metal salt, even if it is a batch type single-liquid addition method in which one is gradually added to the other and mixed, the batch type or continuous type in which both are mixed simultaneously The simultaneous addition method may be used.

  In this way, by mixing and reacting an aqueous solution of alkali soap and metal salt, a mixture of stearic acid metal soap as a main component and a second fatty acid metal soap is formed. Therefore, according to the present invention, the mixture of the stearic acid metal soap and the second fatty acid metal soap is separated from the water by an appropriate means such as filtration and collected, and this is collected. And dried at a temperature equal to or higher than the crystal transition temperature. By lightly loosening the dried product with a finger, an aggregate of metal soap having a bulk specific gravity of 0.5 to 1.0 g / mL can be obtained. Here, according to the present invention, by crushing such an aggregate of metal soap, the average particle size is 1.0 μm or less, and the proportion of particles having a particle size larger than 4 μm is 5% by weight or less. Yes, preferably, a particulate metal soap having a bulk specific gravity of 0.1 g / mL or less can be easily obtained.

  In the present invention, the method of filtering, washing and drying the obtained metal soap is not particularly limited, and may be a conventionally known method. Further, the method for pulverizing the dried metal soap is not particularly limited, and for example, a pin mill, an atomizer, a jet mill or the like can be used.

  According to the present invention, in the production of metal soap by the metathesis method, an aqueous solution containing an alkaline soap of stearic acid and an alkaline soap of a second fatty acid having a melting point of 70 ° C. or more is prepared, and this is mixed with an aqueous solution of a metal salt. The reason for this reaction is not necessarily clear, but when the second fatty acid is used in combination, the metal soap is mixed with the metal stearate so that the crystal growth of the metal stearate soap is suppressed. And it is thought that the effect which prevents aggregation at the time of drying arises.

  In the present invention, the crystal transition temperature of the stearic acid metal soap refers to a temperature at which the crystal structure of the stearic acid metal soap starts to change, and differs depending on the metal type of the metal soap. That is, the crystal transition temperature of the metal soap of stearic acid is 100 ° C for the zinc salt, 94 ° C for the calcium salt, and 73 ° C for the magnesium salt. In the present invention, a particularly preferable drying temperature is in a range from a temperature 5 ° C. higher than the crystal transition temperature of the stearic acid metal soap to a temperature 5 ° C. lower than the melting point. For example, when the obtained metal stearate soap contains zinc stearate as a main component, the drying temperature is preferably in the range of 105 to 118 ° C.

  According to the present invention, an alkaline soap of stearic acid and a predetermined ratio of the second fatty acid alkaline soap and a metal salt are reacted in water, and the resulting stearic acid metal soap is a main component. The mixture of metal soaps is heated at a temperature not lower than the crystal transition temperature of stearic acid metal soap according to the present invention and dried until the water content reaches a predetermined value, whereby the average particle size is 2 μm or more and the particle size is 4 μm. An agglomerate of the above-mentioned metal soap mixture having a particle ratio of 10% or more is obtained. Subsequently, the mixture of such metal soaps is pulverized by ordinary means, whereby the average particle size is easily 1.0 μm or less and the particles having a particle size larger than 4 μm are 5% by weight or less. Can be obtained. According to a preferred embodiment, the particulate metal soap thus obtained according to the present invention has a bulk specific gravity of 0.1 g / mL or less, in particular a bulk specific gravity in the range of 0.05 to 0.1 g / mL. A fine particle metal soap can be obtained.

  When the metal soap obtained by the reaction between the alkali soap and the metal salt is dried at a temperature lower than the crystal transition temperature of the metal soap of stearic acid, which is the main component of the metal soap, the average particle size may be reduced. Although a metal soap of about 1 μm can be obtained, it takes a long time for drying to obtain a predetermined amount of water, which is inferior in production efficiency.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Below, melting | fusing point of the fatty acid was measured using Melting Point B-545 made from BUCHI.

  The second fatty acids used below are all for industrial use. The metal soaps obtained in the following Examples 1 to 7 and Comparative Examples 1 to 4, 8 and 9 are a mixture of a second fatty acid metal soap mainly composed of a metal stearate soap, but simple. For this reason, it is simply called metal stearate soap.

Example 1
Industrial beef tallow stearic acid (stearic acid 65%, palmitic acid 34%, myristic acid 1%, melting point 60.2 ° C) 3.6kg and behenic acid (melting point 78.3 ° C) 0.4kg in 100L of 80 ° C hot water The suspension was suspended, and 1460 mL of 400 g / L sodium hydroxide aqueous solution was added thereto, stirred for 30 minutes, and then cooled to 70 ° C. to prepare an alkaline soap aqueous solution. Separately, 2.2 kg of zinc sulfate heptahydrate crystals were dissolved in 50 L of warm water at 70 ° C. to prepare an aqueous zinc sulfate solution.

  The zinc sulfate aqueous solution was added to the alkali soap aqueous solution at a temperature of 70 ° C. over 30 minutes, and the mixture was aged by stirring for 1 hour while maintaining the temperature of 70 ° C. The metal soap slurry thus obtained is filtered, and the cake obtained is washed with water until the filtrate has a conductivity of 300 μS / cm or less. Subsequently, the cake is washed in a hot air dryer at 110 ° C. for 12 minutes. Dry for hours.

  The particle size distribution and bulk specific gravity before pulverization of the obtained metal soap were measured as follows. That is, lightly loosen the dried cake of the obtained metal soap with a finger, pass through a sieve with an opening of 5.6 mm, add 60 mL of ethanol to 0.1 g of the cake, and use an ultrasonic disperser (manufactured by Nippon Seiki Co., Ltd.). For 2 minutes to prepare a metal soap dispersion. Thereafter, ethanol was used as a measurement solvent, and the dispersion liquid of the metal soap was added to a particle size distribution measuring apparatus (Nikkiso Co., Ltd. Microtrac MT-3000) to measure the particle size distribution of the metal soap. Similarly, the dry cake of the obtained metal soap was lightly loosened with a finger and passed through a sieve having an opening of 5.6 mm, and the bulk specific gravity was measured according to JIS K-6720. The results are shown in Table 1.

  Next, the dried cake was roughly crushed with an atomizer and then pulverized with a jet mill to obtain a zinc stearate powder having a moisture content of 0.5%. For the metal soap powder after pulverization, the particle size distribution and bulk specific gravity were measured using the same measuring apparatus and method as described above.

Comparative Example 1
A zinc stearate powder was obtained in the same manner as in Example 1 except that the drying was performed at 70 ° C. instead of the drying at 110 ° C. However, it took 2 days to make the water content 0.5%.

Example 2
A powder of zinc stearate having a water content of 0.5% in the same manner as in Example 1 except that 3.8 kg of industrial beef tallow stearic acid and 0.2 kg of 12-hydroxystearic acid (melting point: 76.3 ° C.) were used. Got.

Example 3
A powder of zinc stearate having a moisture content of 0.3% was obtained in the same manner as in Example 1 except that 3.4 kg of industrial beef tallow stearic acid, 0.4 kg of behenic acid and 0.2 kg of 12-hydroxystearic acid were used. Obtained.

Example 4
Suspend 3.4 kg of industrial beef tallow stearic acid, 0.4 kg of behenic acid and 0.2 kg of 12-hydroxystearic acid in 100 L of warm water at 80 ° C., add 1460 mL of a caustic potash aqueous solution having a concentration of 560 g / L, and stir for 30 minutes. After cooling to 50 ° C., an alkaline soap solution was prepared. Separately, 2.2 kg of zinc sulfate heptahydrate crystals were dissolved in 50 L of warm water at 50 ° C. to prepare an aqueous zinc sulfate solution.

  The zinc sulfate aqueous solution was added to the alkali soap aqueous solution at a temperature of 50 ° C. over 30 minutes, and the mixture was aged by stirring for 1 hour while maintaining the temperature of 50 ° C. The metal soap slurry thus obtained is filtered, and the cake obtained is washed with water until the filtrate has a conductivity of 300 μS / cm or less. Subsequently, the cake is washed in a hot air dryer at 110 ° C. for 12 minutes. Dry for hours. Next, this was crushed with an atomizer and then pulverized with a jet mill to obtain a zinc stearate powder having a water content of 0.5%.

Comparative Example 2
A zinc stearate powder was obtained in the same manner as in Example 4 except that the drying was performed at 70 ° C. instead of the drying at 110 ° C. However, it took 2 days to make the water content 0.5%.

Example 5
An aqueous calcium chloride solution was prepared by adding 2760 mL of a 300 g / L aqueous calcium chloride solution to 50 L of warm water at 70 ° C. A calcium stearate powder having a moisture content of 2.3% was obtained in the same manner as in Example 1 except that this calcium chloride aqueous solution was used instead of the zinc sulfate aqueous solution.

Comparative Example 3
Instead of drying at 110 ° C., calcium stearate powder was obtained in the same manner as in Example 5 except that drying was performed at 70 ° C. However, it took 2 days to make the water content 2.5%.

Example 6
The reaction was carried out in the same manner as in Example 5 except that 3.5 kg of industrial beef tallow stearic acid, 0.4 kg of behenic acid and 0.1 kg of 12-hydroxystearic acid were used, and calcium stearate having a water content of 2.7% was used. A powder was obtained.

Example 7
A magnesium sulfate aqueous solution was prepared by dissolving 1.9 kg of magnesium sulfate heptahydrate crystals in 50 L of warm water at 70 ° C. A stearic acid solution having a water content of 2.0% was used in the same manner as in Example 1 except that this magnesium sulfate aqueous solution was used in place of the zinc sulfate aqueous solution and the obtained cake was dried overnight in a hot air dryer at 90 ° C. Magnesium powder was obtained.

Comparative Example 4
Magnesium stearate powder was obtained in the same manner as in Example 7 except that drying at 70 ° C. was performed instead of drying at 90 ° C. However, it took 3 days to adjust the moisture to 2.0%.

Comparative Examples 5-7
A metal soap powder was obtained in the same manner as in Example 1, 5 or 7 except that only 4 kg of industrial beef tallow stearic acid was used.

Comparative Example 8
A powder of zinc stearate having a water content of 0.5% was obtained in the same manner as in Example 1 except that 3.6 kg of industrial beef tallow stearic acid and 0.4 kg of lauric acid (melting point: 42.0 ° C.) were used. .

Comparative Example 9
A powder of zinc stearate having a water content of 0.5% was obtained in the same manner as in Example 1 except that 3.96 kg of industrial stearic acid and 0.04 kg of 12-hydroxystearic acid were used.

  As described above, 60 mL of ethanol was added to 0.1 g of the metal soaps obtained in Examples 1 to 7 and Comparative Examples 1 to 9, and dispersed for 2 minutes using an ultrasonic dispersing machine (manufactured by Nippon Seiki Co., Ltd.). Each was treated to prepare a metal soap dispersion. Thereafter, ethanol was used as a measurement solvent, the dispersion liquid of the metal soap was added to a particle size distribution measuring apparatus (Nikkiso Co., Ltd. Microtrac MT-3000), and the particle size distribution of each metal soap was measured. The bulk specific gravity was measured according to JIS K-6720. The results are shown in Table 1.

As is apparent from the results shown in Table 1, according to the examples of the present invention, the particle diameter before pulverization is 2 μm or more, but by pulverizing this, the average particle diameter is 0.5 to 1.0 μm. In this range, a fine particle metal soap having a particle size of 4 μm or more and a ratio of particles of 5% by weight or less can be obtained. On the other hand, when the second fatty acid is not used or the proportion of the second fatty acid is less than 2% by weight, the target average particle diameter can be obtained even if the metal soap obtained by the reaction is pulverized. Is 1.0 μm or less, and it is not possible to obtain a fine particle metal soap in which the proportion of particles having a particle size of 4 μm or more is 5% by weight or less. Even if, for example, lauric acid having a melting point lower than 70 ° C. is used as the second fatty acid, the intended fine metal soap cannot be obtained.

Claims (4)

Lithium, calcium, barium, magnesium, zinc, and an alkaline soap of stearic acid and an alkaline soap of a second straight chain saturated fatty acid having a melting point of 70 ° C. or more and optionally having a hydroxyl group Reaction with one or more metal salts selected from aluminum, copper, iron, lead, cobalt and nickel, and the mixture of the resulting stearic acid metal soap and the second fatty acid metal soap from water The average particle size is 1.0 μm or less and the particle size is larger than 4 μm, characterized in that it is separated and dried at a temperature not lower than the crystal transition temperature of the metal stearate soap and then pulverized. A method for producing a fine particle metal soap having a particle content of 5% by weight or less.   The method for producing a particulate metal soap according to claim 1, wherein the ratio of the second fatty acid is in the range of 2 to 20 wt% with respect to the total amount of stearic acid and the second fatty acid.   The method for producing a fine particle metal soap according to claim 1 or 2, wherein an alkali soap of stearic acid and an alkali soap of the second fatty acid are reacted with a metal salt in water at a temperature in the range of 20 to 95 ° C.   The method for producing a particulate metal soap according to any one of claims 1 to 3, wherein the second fatty acid is at least one selected from behenic acid and 12-hydroxystearic acid.