JPS593930B2 - Method for producing fine spherical silica gel and homogenizer used therein - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing fine spherical silica gel by a stirring method and a homogenizer suitable for use therein.

Silica gel is used as a column packing material for liquid chromatography, Gask 20 chromatography, etc.
It is also used as a carrier for various catalysts for catalytic reactions.

Regarding this silica gel, powdered silica gel and spherical silica gel are conventionally known. Spherical silica gel is superior to powdered silica gel in its performance and usage characteristics, and demand for it is increasing. However, spherical silica gel is not easy to manufacture and is expensive. The present inventors have developed a method to solve these problems by using water glass as a raw material, emulsifying it in a dispersion medium consisting of a mixture of a polar solvent blade and a non-polar solvent, and gelling it in the emulsified state. proposed a method for producing spherical silica gel (Special Publication No. 43639/1989).
. However, although this method is satisfactory in that spherical silica gel can be produced cheaply and easily,35 it is difficult to obtain fine spherical silica gel for the following reasons. But it still wasn't enough. In other words, when mixing and dispersing water glass in a dispersion medium using a stirring blade to prepare a suspended emulsion, there are certain limits to the viscosity of the dispersion medium and the rotational speed of the blades that stir them. , within this limit, the higher the viscosity of the dispersion medium and the higher the rotational speed of the blade, the smaller the size of the dispersed particles.

However, when the stirring blades are rotated at high speed, the centrifugal force causes the liquid surface to form an inverted conical spiral shape, which sucks air from the liquid surface to form fine bubbles, which are dispersed and suspended in the liquid. It will be. Therefore, if the rotational speed of the blade is increased in order to reduce the size of the dispersoid particles, the amount of suction gas will increase in proportion to the speed, increasing the amount of suspended air bubbles and, as a result, decreasing the specific viscosity of the liquid. It will be necessary to do so. In this way, an increase in the rotational speed of the stirring blade inevitably causes a decrease in the viscosity of the dispersion medium, so it is difficult to reduce the particle size of suspended emulsified particles, and if the stirring blade is stirred at too high a speed and takes a long time, , when the dispersed and generated particles begin to assemble again,
There was a fear that they would eventually form a collective.

Therefore, in order to prevent the formation of swirls during high-speed stirring, it is conceivable to use baffles like in general stirrers, but with this method, the flow of the liquid becomes irregular, resulting in the formation of The size of the spherical silica gel particles becomes irregular, resulting in a loss of uniformity. Therefore, the present inventors conducted further intensive research in order to produce fine spherical silica gel by the stirring method without using baffles. In mixing and dispersing the glass sol, we have found that the purpose can be achieved by filling an amount of agitated liquid equal to the internal volume of a stirring container, sealing the container so that it is completely filled with only liquid, and stirring the container at high speed. Based on this finding, the present invention has been completed.

That is, in the present invention, when emulsifying and gelling a water glass sol in a dispersion medium consisting of a mixture of a polar solvent (alcohol) and an alcohol-miscible nonpolar solvent, the dispersion medium containing the water glass sol is placed in a stirring container. To provide a method for producing fine spherical silica gel, which is characterized in that the silica gel is charged, sealed tightly filled with a dispersion medium, stirred at high speed to emulsify, and gelled in this emulsified state, and an apparatus used therein. It is something.

The water glass used in the present invention is a concentrated solution of alkali-silicate glass, and the concentration of the water glass is SiO
Approximately 1 to 50 weight as 2? , preferably 3 to 30 weight?
It is.

Furthermore, as the non-polar solvent, any solvent can be used as long as it is miscible with alcohol, but in general, C5-C
In addition to 2O paraffinic and olefinic hydrocarbon solvents, aromatic solvents can also be used.

Examples of preferred hydrocarbon solvents include pentane, hexane, heptane, octane, dodecane, liquid paraffin,
Examples include octene and dodecene. The mixing ratio of polar solvents (alcohols) and non-polar solvents is usually 1 part by volume of the former to 0.1 to 9 parts by volume, preferably 0.
It is in the range of 5 to 3 parts by volume.

Further, the amount of water glass added to the dispersion medium is generally in the range of 0.1 to 20 parts by weight, preferably 0.5 to 5 parts by weight as SiO2 in the water glass, based on 100 parts by weight of the dispersion medium. It is.

In the method of the present invention, the stirring speed when emulsifying and dispersing water glass in a dispersion medium varies depending on conditions such as the type of dispersion medium and dispersion temperature, but is usually 300 to 5000 rv.
&b{Appropriate, preferably 1000 to 3000 rF.

The silica gel emulsified and dispersed in the method of the present invention is gelled in that state.

As for the gelling method, the same method described in Japanese Patent Publication No. 52-43639 can be applied. Furthermore, separation of the fine spherical silica gel from the dispersion medium can be carried out by conventional means.

Next, a homogenizer suitable for use in the method of the present invention will be explained according to an illustrated embodiment. FIG. 1 is a sectional view of the homogenizer, and FIG. 2 is a perspective view.

In the figure, 1 is an emulsification tank, 2 is a jacket for adjusting the temperature of the emulsification tank 1, and 3 is a lid plate of the emulsification tank 1, whose position can be moved up and down within the emulsification tank. Reference numeral 4 denotes a water glass pouring funnel attached to the lid plate 3, which is equipped with a funnel sealing stopper 5 and moves up and down together with the lid plate 3.

Reference numeral 6 denotes a guide plate attached above the lid body 3 by a connecting pin 7, and a skirt portion 6a formed by bending downward extends from the edge thereof.

The guide plate 6 moves up and down together with the lid plate 3. 8 is a stirring blade, 9 is its rotating shaft, 10 is a bearing, and 11 is a pulley.

Note that 12 is an O-ring that seals between the lid plate 3 and the inner wall of the emulsification tank 1, 13 is an O-ring that seals between the lid plate 3 and the rotating shaft 9, and 14 is a quick drain valve. be. The mechanism for vertical movement of the cover plate 3 of this homogenizer is as follows. First, a ring 15 for attaching guide pins is fixed to the outer edge of the side wall of the emulsification tank 1, and guide pins 16 having ball bearings 16a on their heads are attached at several places on the ring. On the other hand, the skirt portion 6a of the guide plate 6 is formed with a guide groove 6b having an inclination of approximately 30° (see Fig. 2), and the ball bearing 16a at the head of the guide pin 16 rolls into this guide groove 6b. They fit together freely. Therefore, when the guide plate 6 is rotated in the direction of the arrow p, the guide plate 6 descends while rotating along the ball bearing 16a of the head of the guide pin 16 into which the guide groove 6b of the skirt portion 6a fits. Therefore, the cover plate 3 also descends. In this case, since the slope of the guide groove 6b is as high as 300, it is sufficient to rotate the guide plate 6 by 1/6 to 1/4 in order to obtain a predetermined height difference. The vertical position can be adjusted extremely quickly. In the illustrated embodiment, the skirt portion 6a is formed on the outside of the emulsification tank 1, but if the emulsification tank 1 becomes larger, a skirt portion from the guide plate 6 is formed inside the emulsification tank, and a guide plate is formed on the inside of the emulsification tank. Of course, grooves may also be formed.

In order to emulsify and disperse water glass in a dispersion medium using the homogenizer of the present invention, the dispersion medium and water glass are charged into the emulsification tank 1, the guide plate 6 is rotated to lower the cover plate 3, and the cover plate 3 is lowered by rotating the guide plate 6. After adjusting the volume tightly sealed by 3 to be equal to the volume of the charged liquid, the stirring blade 8 is rotated at high speed to effect emulsification and dispersion.

Although not shown, the pulley 9 is driven by a transmission means such as a belt by a drive motor via a continuously variable transmission.
As described above, the method of the present invention has the excellent effect of producing fine and uniformly sized spherical silica gel very efficiently.

On the other hand, the homogenizer of the present invention can adjust the vertical position by lowering the lid plate very quickly and easily after charging the water glass and dispersion medium, and under closed conditions with the container filled with the charged liquid. It is suitable for high-speed stirring. Further, according to the homogenizer of the present invention, it is possible to prevent the silica gel that has been dispersed and generated from re-aggregated during stirring, and it is possible to prepare uniform and fine silica gel in a short time. Next, the present invention will be explained in more detail based on examples.

Example Using the homogenizer shown in Figures 1 and 2, fine spherical silica gel was prepared as follows.

First, as a dispersion medium, 500 m
1 was placed in an 11-volume emulsification tank 1, the temperature was kept constant at 0° C.±1° C., and 4 blades, a stirring blade 8 having a diameter of 65 m1, were immersed therein. Separately, put 50 ml of 2N hydrochloric acid in a 200 ml beaker, stir well with a magnetic stirrer while maintaining the liquid temperature at 5°C, and add 280 g of No. 1 sodium silicate and 400 ml of water. Aqueous sodium chloride solution was added dropwise using a burette, adding 34.12 d of hydro-silica sol (84.12 d of hydro-silica sol at this temperature).
(gels in seconds) was prepared. Next, the stirring blade 8 is rotated at a rotation speed of 1000 rpm? 1500rP1 or 2000rP
? By rotating the guide plate 6, the lid plate 3 is lowered, and the volume sealed thereby is adjusted to be equal to the volume of the liquid to be prepared. The above-prepared silica sol solution was added in about 20 seconds (after the addition was complete, a small amount of the silica sol solution was left in a 200 WLI beaker, and the time until it solidified was measured; (confirmed to be seconds).

After the addition of the silica sol solution is completed, with the volume tightly sealed with the lid plate 3 filled with the prepared liquid, high-speed stirring is performed at each of the above-mentioned rotation speeds for 4 minutes, then the speed is reduced to 400 rotations, and immediately Add over 250d of water cooled to ℃,
Gel aggregation from the emulsified suspension was prevented and the formed silica gel was transferred from the dispersion medium to the aqueous phase. After standing, the gel was separated from the aqueous phase, washed with water, heated at 80°C for 1 hour in the hydrogel state, dehydrated by a freezing method, and the resulting gel was washed with methanol and heated at 80°C. When I dried it by heating for 1 hour and examined it under a microscope, the rotation speed was 1000 rpm? 1500rp
In the case of 12000rp1, each particle size is uniform and 20~
It was found that 23μ, 10-13μ, and 3-6μ were obtained. On the other hand, for comparison, the rotation speed of the stirring blade was set to 2000 rpm? 3000rpI1 or 4000r
p? Silica gel was prepared in the same manner as above, except that the lid plate 3 was raised and a space was provided above the charged liquid in the emulsification tank 1 for high-speed stirring. The particles were uniform, but the rotation speed was 2000 rpm, 13000 rF, 4000 rpm, and the particles were 20-23μ, 15-18μ, and 10-13μ, respectively.
It was hot.

Furthermore, the mixing ratio of the dispersion medium was changed to 3 parts by volume of n-hexanol,
Even if 7 parts by volume of liquid paraffin (kinematic viscosity 26v) was used and the rotational speed was increased to 4000 rpm, no silica gel with a particle size of 8 μm or less could be obtained. Figures 3 and 4 show photographs of the silica gel thus obtained.

FIG. 3 shows silica gel particles obtained by the method of the present invention at a rotation speed of 2000 rF, and FIG. 4 shows the above comparative example in which the mixing ratio of the dispersion medium was 4 parts by volume of n-hexanol and 6 parts by volume of liquid paraffin. It represents silica gel particles at a rotational speed of 4000 rpm. From this photo comparison,
It can be seen that according to the present invention, spherical silica gel that is finer and more uniform in size can be easily produced. That is,
According to the present invention, fine spherical silica gel having a uniform particle size of 5 μm or less can be produced with high yield without using a sieve, so it can be used not only for analysis but also for preparative purposes. The economic effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a homogenizer as an embodiment of the present invention, FIG. 2 is a perspective view of the same homogenizer, and FIG.
The figure is a photograph of silica gel obtained by the method of the present invention, No. 4.
The figure is a photograph of silica gel obtained by a conventional method. Explanation of symbols, 1... Emulsification tank, 3... Lid plate, 4... Funnel for adding water glass, 6...
・Guide plate, 6a...Skirt part, 6b...
... Guide groove, 8 ... Stirring blade, 16.
...Guide pin, 16a...Ball bearing.

Claims (1)

[Claims] 1. When emulsifying and gelling a water glass sol in a dispersion medium consisting of a mixture of a polar solvent (alcohol) and an alcohol-miscible non-polar solvent, the water glass sol is placed in a stirring container. 1. A method for producing fine spherical silica gel, which comprises: charging a dispersion medium containing the liquid, sealing the dispersion medium completely filled with the charged liquid, and then stirring at high speed to emulsify. 2. A lid body that seals the inner upper part of the stirring type emulsification tank is combined with a guide plate provided above the lid body, and a skirt part that hangs downward is formed on the guide plate, and a skirt part is formed in the skirt part. Forming a guide groove with a predetermined slope,
On the other hand, a guide pin is attached to the side wall surface of the emulsification tank, and this is fitted into the guide groove, and the guide plate connected to the lid body is rotated so that the guide pin moves in the guide groove of a predetermined slope. By doing so, the height can be adjusted by raising and lowering the guide plate and raising and lowering the lid, so that the lid can be sealed without any gaps when the liquid is filled. homogenizer.