JP5099804B2 - Method for producing basic sodium alum - Google Patents

Description

The present invention relates to a method for producing basic sodium alum.

As a method for producing basic alum, aluminum sulfate and alkali sulfate are heated and reacted in an aqueous medium to which alkali hydroxide has been added so that the pH does not fall below 3.8, and alunite crystals having a large specific surface area (Na-type crystals). , K-type, NH ₄ -type basic alum) has been proposed (see, for example, Patent Document 1).

Further, as a method for producing a spindle-shaped or spherical basic alum, a method has been proposed in which a basic alum having a particle size of 0.5 to 15 μm is obtained by hydrothermal treatment of aluminum sulfate, alkali sulfate and aluminum hydroxide. (See, for example, Patent Document 2).
JP-A 64-11637 JP 2000-7326 A

  In recent years, the use of basic alum as a gas adsorbent, an adsorbent for dyes in liquids, a hygroscopic agent, a resin additive, and a paper filler has been investigated. Therefore, it is required to be closer to a true sphere, have a large specific surface area, and be monodispersed.

However, the method disclosed in the above-mentioned patent document has a problem in that it cannot provide a basic alum that can meet such requirements. That is, when an alkali hydroxide such as sodium hydroxide is added as in the method disclosed in Patent Document 1, amorphous alumina hydrate is mixed, and a spherical basic alum cannot be produced. In addition, in the method disclosed in Patent Document 2, even if a spherical basic alum can be produced, the sphericity is extremely low, the specific surface area is small at 30 m ² / g, and the particle size is large. There is a problem that the dispersion of the particle diameter is large.

In view of the above problems, an object of the present invention is to realize a production method capable of providing a new basic sodium alum having unprecedented characteristics in terms of shape and specific surface area. .

In order to solve the above problems, in the method for producing basic sodium alum (NaAl ₃ (SO ₄ ) ₂ (OH) ₆ ) according to the present invention, a predetermined temperature condition is applied to an aqueous solution containing aluminum sulfate and sodium carbonate. It is characterized in that a basic sodium alum is obtained from the heat-treated liquid by performing the following heat treatment.

In the method for producing basic sodium alum according to the present invention , a heat treatment under a predetermined temperature condition is performed on an aqueous solution containing aluminum sulfate and sodium carbonate, and in obtaining a basic sodium alum from the heat-treated liquid, In the heat treatment, a first heating step for holding the aqueous solution at a first temperature, and a second temperature for holding the aqueous solution at a second temperature higher than the first temperature after the first heating step. The heating step is performed. Therefore , crystalline basic sodium alum particles having a spherical shape with a ratio of the dimension in the minor axis direction to the dimension in the major axis direction of 0.7 to 1: 1 and a specific surface area of 200 m ² / g or more are produced. it can. In addition, according to the present invention, in the particle size distribution measured by the dynamic light scattering method, the basic sodium alum of monodispersed particles in which 80% or more of all particles are contained within a range of ± 50% of 50% particle size. Can be manufactured. That is, basic sodium alum particles having a uniform particle diameter can be produced. Furthermore, according to the present invention, the reaction temperature needs to be 60 ° C. or higher, but the particle diameter can be controlled by the reaction temperature, and the basic sodium alum having a smaller particle diameter can be produced as the reaction temperature is lowered. Therefore, according to the present invention, it is possible to produce a fine basic sodium alum having a 50% particle size of 1.5 μm or less, and further 0.5 μm or less. It can be controlled in the range of ˜1.5 μm.

  The particle size distribution data can be expressed as cumulative percentage or frequency percentage with respect to the particle size scale, but “50% particle size” means that the cumulative distribution curve of 50% is expressed as the particle size with respect to the cumulative percentage scale. The particle diameter at the point that intersects the scale axis, which means that “80% or more of all particles are included in the ± 50% range of 50% particle diameter” means that the cumulative curve of 50% is the horizontal axis. It means that 80% or more of all particles are included in the range of ± 50% with respect to the intersecting point (50% particle diameter).

  In this case, it is preferable to add seed particles of basic sodium alum to the aqueous solution in the first heating step. When such a method is adopted, the yield of basic sodium alum can be improved. In adding seed particles, it is preferable that the seed particles to be added are small. By reducing the seed particles to be added, the particle diameter of the basic sodium alum obtained by the reaction can be reduced. In addition, when adding seed particles, the method of adding basic sodium alum particles produced by the method according to the present invention, or the basic sodium alum produced by the method according to the present invention or other than according to the present invention There is a method in which particles of basic sodium alum produced by the method are pulverized by a ball mill or the like. In the latter case, seed particles having a smaller 50% diameter can be easily produced by obtaining seed particles by pulverization.

  In the present invention, the seed particles are preferably added at the end of the first heating step. When seed particles are added at such timing, the particle diameters can be made more uniform.

The basic sodium alum according to the present invention has a spherical shape with a ratio of the dimension in the minor axis direction to the dimension in the major axis direction of 0.7 to 1: 1, and has a specific surface area of 200 m ² / g or more. Features. That is, the sodium alum particles according to the present invention are substantially spherical and have a specific surface area of 200 m ² / g or more .

In the present invention, the specific surface area can be achieved by, for example, a basic sodium alum having a large number of pores having a pore diameter of 4 nm or less, which are open on the surface.

  In the present invention, basic sodium alum can be produced as monodisperse particles in which 80% or more of all particles are contained within a ± 50% range of 50% particle diameter in a particle size distribution measured by a dynamic light scattering method. it can.

  In the present invention, a fine basic sodium alum having a 50% particle size of 1.5 μm or less and further 0.5 μm or less can be produced in the particle size distribution measured by the dynamic light scattering method.

  The basic alum according to the present invention is used as a gas adsorbent, a dye adsorbent in liquid, a hygroscopic agent, a resin additive, a paper filler, a toner core used in a copying machine, an additive for cosmetics, etc. Can do.

Among these uses, when the basic alum according to the present invention is used for a gas adsorbent, a dye adsorbent in liquid, and a hygroscopic agent, it is porous and has a specific surface area of 200 m ² / g or more. There are advantages such as high adsorption ability of gas, pigment and moisture.

  When the basic alum according to the present invention is used for the resin additive and the paper filler, since it is a substantially true sphere, the antiblocking property is excellent and the monodispersed particles have high dispersibility in the matrix. There are advantages such as.

  When the basic alum according to the present invention is used as a toner core material used in a copying machine or the like, the particle size is small and monodispersed particles, so that an image can be developed faithfully and transfer with a high transfer rate is performed. There are advantages such as being able to.

  When the basic alum according to the present invention is used as an additive to cosmetics, it is an almost true sphere, so that it has excellent anti-blocking properties and monodispersed particles, so that the dispersibility in the matrix is high. and so on. In addition, since the particle size is small and it is porous, there are advantages such as high concealment ratio against ultraviolet rays.

In the method for producing basic sodium alum according to the present invention , a heat treatment under a predetermined temperature condition is performed on an aqueous solution containing aluminum sulfate and sodium carbonate, and in obtaining a basic sodium alum from the heat-treated liquid, In the heat treatment, a first heating step for holding the aqueous solution at a first temperature, and a second heating step for holding the aqueous solution at a second temperature higher than the first temperature after the first heating step; to perform the ratio of dimension in dimension and a major axis direction in the short-axis direction of 0.7: has one of spherical, specific surface area can be produced 200 meters ² / g or more basic sodium alum. Further, in the particle size distribution measured by the dynamic light scattering method, monodispersed particles in which 80% or more of all particles are included in a range of ± 50% of 50% particle size, and the 50% particle size is 1.5 μm. In the following, a fine basic sodium alum having a size of 0.5 μm or less can be produced.

  Basic sodium alum is produced by the methods of Examples 1 to 5 described below, and crystal type identification, particle size distribution / 50% particle size measurement, shape observation, specific surface area measurement, pore size distribution / pore size measurement are performed. It was. Among these evaluations, an X-ray diffractometer RINT2000 manufactured by Rigaku Corporation was used for crystal type identification. The particle size distribution / 50% particle size measurement was performed by a dynamic scattering method using a particle size distribution measuring device Nanotrac UPA150EX manufactured by Microtrac, after the sample was dispersed in water. In the shape observation, the short axis and long axis dimensions of the basic sodium alum particles on the image were measured using a photographic image taken using a scanning electron microscope S-3100H manufactured by Hitachi, Ltd. In the specific surface area measurement and pore diameter distribution / pore diameter measurement, the sample dried at 150 ° C. was measured by a gas adsorption method using a specific surface area measuring device Tristar 3000 manufactured by Micromeritics.

  Examples 1 to 5 below will be described. FIG. 1 shows a reaction schedule in each example, and FIG. 2 shows an imaging result of the basic sodium alum obtained in Example 1 with an electron microscope.

(Example 1)
In a 1000 ml separable beaker, 750 g of an aluminum sulfate aqueous solution (concentration of Al ₂ O ₃ = 8 wt%) was taken, and 293 g of a 32 wt% sodium carbonate aqueous solution was added dropwise over 30 minutes while stirring this.

  Next, as shown by a solid line L1 in FIG. 1, in the first heating step, the solution was heated to 60 ° C. over 30 minutes and then held at 60 ° C. for 1 hour in the first heating step. .

  Next, in the second heating step, the temperature was raised to 85 ° C. over 30 minutes, and then held at 85 ° C. for 30 minutes in the second heating step. The pH during and after the reaction was in the range of 3.4 to 3.7.

  Next, it was cooled, filtered using a filter paper, washed, and dried at 120 ° C. to obtain 102 g of powder. When the yield was 100%, it was 156 g, and the yield in this example was 65.4%.

As a result of crystal type identification of the powder by X-ray diffraction, it was confirmed that it was crystalline basic sodium alum (NaAl ₃ (SO ₄ ) ₂ (OH) ₆ ).

  Moreover, when the obtained powder was observed with the electron microscope, the photographic image shown in FIG. 2 was obtained. Moreover, when the ratio of the dimension in the minor axis direction to the dimension in the major axis direction of each granule was measured from the photographic image, it was confirmed that it had a spherical shape of 0.7 to 1: 1, and a substantially true spherical base. It was confirmed that it was a sodium sodium alum.

The pore size distribution of the basic sodium alum obtained in this example is shown in FIG. As shown in FIG. 3, it was confirmed that the basic sodium alum obtained in this example had a large number of pores having a pore diameter of 4 nm or less, and the pore size was uniform. Further, when the specific surface area of the powder was measured, it was about 300 m ² / g or more and 330 m ² / g due to the surface area expansion effect by the pores.

  Furthermore, when the obtained basic sodium alum is subjected to a heat treatment, it is recognized that the pore diameter expands. For example, the measurement result of the pore size distribution after heating at 250 ° C., 300 ° C., 350 ° C. As shown in FIG. 4, it has also been confirmed that the pore diameter can be arbitrarily controlled according to the heat treatment temperature.

  Furthermore, the measurement result of the particle size distribution (cumulative% distribution, frequency% distribution) of the basic sodium alum obtained in this example by the dynamic light scattering method is shown in FIG. As shown in FIG. 5, the basic sodium alum obtained in this example has a 50% particle size of 0.39 μm, and 89% of all particles are contained within a ± 50% range of the 50% particle size. It was confirmed that the particles were monodispersed particles.

(Example 2)
In this example, the same operation as in Example 1 was performed except that the second temperature in the second heating step was changed to 95 ° C. First, 750 g of an aluminum sulfate aqueous solution (concentration of Al ₂ O ₃ = 8 wt%) was taken into a 1000 ml separable beaker, and 293 g of a 32 wt% sodium carbonate aqueous solution was added dropwise over 30 minutes while stirring this.

  Next, as indicated by a dotted line L2 in FIG. 1, in the first heating step, the solution was heated to 60 ° C. over 30 minutes, and then held at 60 ° C. for 1 hour in the first heating step.

  Next, in the second heating step, the temperature was raised to 95 ° C. over 30 minutes, and then held at 95 ° C. for 30 minutes in the second heating step. The pH during and after the reaction was in the range of 3.4 to 3.7.

  Next, it was cooled, filtered and washed with filter paper, and dried at 120 ° C. to obtain 150 g of powder. The yield in this example was 96.2%.

As a result of crystal type identification of the powder by X-ray diffraction, it was confirmed that it was a basic sodium alum (NaAl ₃ (SO ₄ ) ₂ (OH) ₆ ) as in Example 1. Further, when the obtained powder was observed with an electron microscope, a photographic image similar to that in Example 1 was obtained, and the ratio of the dimension in the minor axis direction to the dimension in the major axis direction was measured. It was confirmed to have a 1: 1 spherical shape. Further, on the surface of the powder, a large number of pores having a pore diameter of 4 nm or less were opened and the pore sizes were uniform. Further, when the specific surface area of the powder was measured, it was about 300 m ² / g or more and 311 m ² / g due to the surface area expansion effect by the pores.

  Moreover, the measurement result of the particle diameter distribution (cumulative% distribution, frequency% distribution) of the basic sodium alum obtained in this example by the dynamic light scattering method is shown in FIG. As shown in FIG. 6, the basic sodium alum obtained in this example has a 50% particle size of 1.24 μm, and 90% of all particles are contained within ± 50% of the 50% particle size. It was confirmed that the particles were monodispersed particles.

  Thus, in this example, since the temperature of the second heating step was set to 95 ° C. higher than that of Example 1, the yield was improved while the 50% particle size was large. That is, in the present invention, it can be said that the particle diameter of basic sodium alum can be controlled by the second temperature of the second heating step.

Example 3
In this example, the same operation as in Example 1 was performed except that the second temperature in the second heating step was changed to 95 ° C. and the holding time in the second heating step was changed to 20 minutes. First, 750 g of an aluminum sulfate aqueous solution (concentration of Al ₂ O ₃ = 8 wt%) was taken into a 1000 ml separable beaker, and 293 g of a 32 wt% sodium carbonate aqueous solution was added dropwise over 30 minutes while stirring this.

  Next, as indicated by a dotted line L2 in FIG. 1, in the first heating step, the solution was heated to 60 ° C. over 30 minutes, and then held at 60 ° C. for 1 hour in the first heating step.

  Next, in the second heating step, the temperature was raised to 95 ° C. over 30 minutes, and then held at 95 ° C. for 20 minutes in the second heating step. The pH during and after the reaction was in the range of 3.4 to 3.7.

  Next, it was cooled, filtered and washed with filter paper, and dried at 120 ° C. to obtain 119 g of powder. The yield in this example was 76.3%.

As a result of crystal type identification of the powder by X-ray diffraction, it was confirmed that it was a basic sodium alum (NaAl ₃ (SO ₄ ) ₂ (OH) ₆ ) as in Example 1. Further, when the obtained powder was observed with an electron microscope, a photographic image similar to that in Example 1 was obtained, and the ratio of the dimension in the minor axis direction to the dimension in the major axis direction was measured. It was confirmed to have a 1: 1 spherical shape. However, there were almost no pores, and the specific surface area of the powder was measured and found to be 24 m ² / g.

  Further, in the measurement result of the particle size distribution by the dynamic light scattering method, the monodispersion in which the 50% particle size is 1.0 μm and 82% of all particles are included in the ± 50% range of the 50% particle size. It was confirmed to be particles.

Example 4
In this example, the same operation as in Example 1 was performed except that seed particles were added in the first heating step. That is, first, 750 g of an aluminum sulfate aqueous solution (concentration of Al ₂ O ₃ = 8 wt%) was taken into a 1000 ml separable beaker, and 293 g of a 32 wt% sodium carbonate aqueous solution was added dropwise over 30 minutes while stirring this.

  Next, as indicated by a solid line L1 in FIG. 1, in the first heating step, the solution was heated to 60 ° C. over 30 minutes, and then held at 60 ° C. for 1 hour in the first heating step. Next, 0.5 g of basic sodium alum particles produced in Example 1 were added as seed particles at the time indicated by arrow A (the final stage of the first heating step).

  Next, after raising the temperature to 85 ° C. over 30 minutes in the second temperature raising step, the temperature was kept at 85 ° C. for 30 minutes in the second heating step. The pH during and after the reaction was in the range of 3.4 to 3.7.

  Next, it was cooled, filtered and washed with filter paper, and dried at 120 ° C. to obtain 150 g of powder. The yield in this example was 96.2%.

As a result of crystal type identification of the powder by X-ray diffraction, it was confirmed that it was a basic sodium alum (NaAl ₃ (SO ₄ ) ₂ (OH) ₆ ) as in Example 1. Further, when the obtained powder was observed with an electron microscope, a photographic image similar to that in Example 1 was obtained, and the ratio of the dimension in the minor axis direction to the dimension in the major axis direction was measured. It was confirmed to have a 1: 1 spherical shape. Further, on the surface of the powder, a large number of pores having a pore diameter of 4 nm or less were opened and the pore sizes were uniform. Moreover, when the specific surface area of the powder was measured, it was about 300 m ² / g or more and 344 m ² / g due to the surface area expansion effect by the pores.

  Furthermore, in the measurement result of the particle size distribution by the dynamic light scattering method, the monodispersion in which the 50% particle size is 0.4 μm and 85% of all particles are included in the ± 50% range of the 50% particle size. It was confirmed to be particles.

  Thus, in this example, as in Example 1, the second temperature in the second heating step was set to 85 ° C., so that a basic sodium alum having a 50% particle size of 0.4 μm can be obtained, and Since seed particles were added in the first heating step, higher results than in Example 1 could be obtained in terms of yield.

(Example 5)
In this example, the same operation as in Example 4 was performed, except that the method for creating seed particles to be added in the first heating step was changed. That is, first, 750 g of an aluminum sulfate aqueous solution (concentration of Al ₂ O ₃ = 8 wt%) was taken into a 1000 ml separable beaker, and 293 g of a 32 wt% sodium carbonate aqueous solution was added dropwise over 30 minutes while stirring this.

  Next, as indicated by a solid line L1 in FIG. 1, in the first heating step, the solution was heated to 60 ° C. over 30 minutes, and then held at 60 ° C. for 1 hour in the first heating step. Next, at the time indicated by arrow A (the end of the first heating step), particles having a 50% particle diameter of 0.2 μm obtained by pulverizing the basic sodium alum produced in Example 2 with a ball mill are obtained. 0.5 g was added as seed particles.

  Next, after raising the temperature to 85 ° C. over 30 minutes in the second temperature raising step, the temperature was kept at 85 ° C. for 30 minutes in the second heating step. The pH during and after the reaction was in the range of 3.4 to 3.7.

  Next, it was cooled, filtered and washed with filter paper, and dried at 120 ° C. to obtain 148 g of powder. The yield in this example was 94.8%.

As a result of crystal type identification of the powder by X-ray diffraction, it was confirmed that it was a basic sodium alum (NaAl ₃ (SO ₄ ) ₂ (OH) ₆ ) as in Example 1. Further, when the obtained powder was observed with an electron microscope, a photographic image similar to that in Example 1 was obtained, and the ratio of the dimension in the minor axis direction to the dimension in the major axis direction was measured. It was confirmed to have a 1: 1 spherical shape. Further, on the surface of the powder, a large number of pores having a pore diameter of 4 nm or less were opened and the pore sizes were uniform. Moreover, when the specific surface area of the powder was measured, it was about 300 m ² / g or more and 328 m ² / g due to the surface area expansion effect by the pores.

  Further, in the measurement result of the particle size distribution by the dynamic light scattering method, the 50% particle size is 0.27 μm, and a single particle in which 81% or more of all particles are included in the ± 50% range of the 50% particle size. It was confirmed to be dispersed particles.

  As described above, in this example, seed particles were added in the first heating step in the same manner as in Example 3, and the added seed particles were pulverized with a ball mill to reduce the 50% particle size as 0.2 μm seed particles. A basic sodium alum having a particle size of 50% smaller than that of Example 4 could be obtained, and the same results as in Example 4 could be obtained in terms of yield.

  It should be noted that when the timing of adding the seed particles is changed to the temperature raising step indicated by arrow B or the second heating step indicated by arrow C instead of the end of the first heating step indicated by arrow A, The result is that the rate cannot be improved. Moreover, if the timing which adds a seed particle is a 1st heating process, a substantially equivalent yield can be obtained. Therefore, the timing for adding the seed particles may be set at any time in the first heating step.

  Furthermore, when the timing of adding seed particles is set at the end of the first heating step indicated by arrow A, there is an advantage that the particle diameters can be made uniform.

It is explanatory drawing which shows the reaction schedule in the manufacturing method of the basic sodium alum which concerns on Examples 1-3 of this invention. It is explanatory drawing which shows the imaging result in the electron microscope of the basic sodium alum which concerns on Example 1 of this invention. It is a graph which shows the measurement result of the pore diameter distribution of the basic sodium alum which concerns on Example 1 of this invention. It is a graph which shows the measurement result of pore diameter distribution after heat-processing with respect to the basic sodium alum which concerns on Example 1 of this invention. It is a graph which shows the measurement result of the particle diameter distribution (cumulative% distribution, frequency% distribution) by the dynamic light scattering method of basic sodium alum concerning Example 1 of the present invention. It is a graph which shows the measurement result of the particle diameter distribution (cumulative% distribution, frequency% distribution) by the dynamic light scattering method of the basic sodium alum which concerns on Example 2 of this invention.

Claims (3)

When an aqueous solution containing aluminum sulfate and sodium carbonate is subjected to heat treatment under a predetermined temperature condition to obtain basic sodium alum from the heat-treated liquid,
In the heat treatment, a first heating step for holding the aqueous solution at a first temperature, and a second temperature for holding the aqueous solution at a second temperature higher than the first temperature after the first heating step. The basic sodium alum manufacturing method characterized by performing these heating processes.   2. The method for producing basic sodium alum according to claim 1, wherein seed particles of basic sodium alum are added to the aqueous solution in the first heating step.   3. The method for producing basic sodium alum according to claim 2, wherein the seed particles are added at the end of the first heating step.