JP2588306B2 - Porous bead and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a porous bead of inorganic powder that can be used as a sustained-release body, a catalyst carrier, and the like, and a method for producing the same.

[Prior art] As a method for producing a bead based on an inorganic powder,
A method of press-forming inorganic powder as it is, a method of adding a water-soluble polymer binder or an inorganic binder to the inorganic powder and forming the powder into a spherical shape with a stirrer, and a method of manufacturing microcapsules. Methods such as a method of obtaining a spherical molded body by dropping an aqueous suspension comprising a molecular binder into a curing agent bath (Japanese Patent Publication No. 63-63229) have been conventionally known.

One of the uses of such beads based on inorganic powder is as a sustained-release body. The sustained-release body absorbs and adsorbs substances to be emitted such as fragrances, deodorants, insecticides, insect repellents, fungicides, and attractants, and gradually diffuses the substances. The main substances required for such a sustained-release body are to absorb the substance to be released quickly and to adsorb or retain as much as possible, and to release the adsorbed or retained substance to be released little by little over a long period of time. In addition, the substance to be adsorbed or retained can be stably retained for a long time without causing any chemical change.

[Problems to be Solved by the Invention] However, the beads of the inorganic powder manufactured by the conventional manufacturing method as described above have a slow suction rate of the substance to be diffused, and the adsorption or holding amount of the substance to be diffused is low. It had disadvantages such as less. In other words, inorganic powders having a high BET specific surface area generally have a high rate of absorbing and adsorbing substances to be emitted, and also have a large amount.However, conventional methods using such inorganic powders having a high BET specific surface area are used. Even if a bead is manufactured with such a material, the characteristics such as the absorption and adsorption speed and the amount of absorption and absorption originally possessed by the inorganic powder itself are not exhibited. The bead had not been obtained.

An object of the present invention is to solve such a conventional problem and to provide a porous bead having a high absorption and adsorption rate and a large absorption and adsorption amount, and a method for producing the same.

[Means for Solving the Problems] The porous bead of the present invention is a porous bead obtained by solidifying an inorganic powder with a binder made of an organic polymer, and foams from the inside when the inorganic powder is solidified with a binder. It is characterized in that pores leading to the outside are formed by the formation.

The inorganic powder used in the present invention is appropriately selected depending on its use, and is not particularly limited. When used as a sustained-release body or the like, for example, Ca / P (molar ratio) = 1.0 to 2.0 calcium phosphate compounds, ceramic powders such as silicon oxide and aluminum oxide such as silica gel, silica, and alumina, talc, mica, kaolin clay, calcined clay, bentonite, pyrophyllite, attapulgite, nepheline cyenite Mineral powders such as diatomaceous earth, zeolite, sericite, calcium silicate, aluminum silicate, glass powder and silicate powders, carbonates such as calcium carbonate, calcium magnesium carbonate and magnesium carbonate, hydroxide Hydroxides such as aluminum and magnesium hydroxide, calcium sulfate Sulfates and sulfites such as calcium oxide, calcium sulfite, and barium sulfate; oxides such as iron oxide, titanium oxide, and zinc oxide; inorganic balloons such as shirasu balloons and fly ash balloons; and carbon-based powders such as graphite and activated carbon. Etc. can be used.

In the porous bead of the present invention, when the inorganic powder is solidified by the binder, the pores formed by foaming from the inside are formed so as to communicate with the outer surface of the bead, and are open to the outside. Are pores. The diameter of the pores is appropriately selected depending on the use of the porous bead and the like, but generally, the average of the pore diameters is 0.
It is preferably within the range of 01 mm to 1 mm. More preferably, it is in the range of 0.1 mm to 0.5 mm.

The production method of the present invention is a method capable of producing the above-described porous bead, and includes an inorganic powder, an inorganic powder slurry containing a water-soluble binder and a foaming agent, and an environment for foaming the foaming agent, And preparing a binder insolubilizing bath containing an insolubilizing agent for insolubilizing the water-soluble binder, and dropping the inorganic powder slurry in the binder insolubilizing bath,
Insolubilizing the water-soluble binder while foaming the foaming agent in the inorganic powder slurry and solidifying it in the form of beads.

In the present invention, the gas to be foamed is not particularly limited, but for example, carbon dioxide gas, nitrogen gas, hydrogen gas and the like can be used. Carbon dioxide is particularly preferred from the viewpoints of handling, economy and availability of the foaming agent.

In order to generate carbon dioxide gas, there are a method of causing an acid to act on a carbonate, a method of heating a hydrogen carbonate such as sodium hydrogen carbonate, and a method of heating ammonium carbonate.

The carbonate as a foaming agent for foaming carbon dioxide gas is not particularly limited, but specifically, as a monovalent metal carbonate, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, Copper carbonate, silver carbonate, etc., as divalent metal carbonates, cadmium carbonate,
Examples thereof include calcium carbonate, cobalt carbonate, magnesium carbonate, strontium carbonate, nickel carbonate, barium carbonate, manganese carbonate, zinc carbonate, iron carbonate, and lead carbonate. These carbonates can be used alone or in combination of two or more.

In the present invention, the binder insolubilizing bath for insolubilizing the binder has an environment for foaming the blowing agent. In the case of using a carbonate as a foaming agent to cause foaming by the action of an acid, it is preferable that the pH of the binder insolubilizing bath is always 4 or less, and more preferably the pH is kept at 3 or less.
As the acid to be used, mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and the like are preferable, but if necessary, organic acids and the like may be used.

When sodium bicarbonate, ammonium carbonate, or the like is used as the foaming agent and foaming is performed by heating, the temperature of the binder insolubilizing bath must be equal to or higher than the decomposition temperature of the foaming agent. In the present invention, since a porous bead is produced in an aqueous system using a water-soluble binder, it is preferable to use a foaming agent that decomposes at a temperature lower than the boiling point of water. Such materials include sodium hydrogen carbonate and ammonium carbonate as described above.

The water-soluble binder used in the present invention is not particularly limited as long as it can be insolubilized in an aqueous solution and can solidify an inorganic powder. As such,
For example, there are alkali metal salts of water-soluble organic polymers. Examples of the alkali metal salt of such a water-soluble organic polymer include sodium alginate, sodium polyacrylate, sodium carboxymethylcellulose, and sodium polystyrene sulfonate. These water-soluble binders can be used alone or in combination of two or more.

In the present invention, as the insolubilizing agent for insolubilizing the water-soluble binder, in the case of an alkali metal salt of a water-soluble organic polymer, a metal which substitutes for an alkali metal ion of the water-soluble organic polymer to insolubilize the organic polymer in water is used. There are water-soluble metal salts that provide ions. Such metal salts include hydrochloride, sulfate, nitrate, acetate, etc.
As the metal of the inorganic salt, Ag, Cu, Cd, Ca, Co, Mg, Sr,
Examples include Ni, Ba, Mn, Sn, Zn, Fe, Pb, U, and Al. Such insolubilizing agents can be used alone or as a mixture of two or more.

When sodium polystyrene sulfonate is used as the water-soluble binder, an organic ammonium salt such as polyvinylbenzoyltrimethylammonium chloride can be used as the insolubilizing agent.

In the present invention, the ratio between the inorganic powder and the foaming agent is preferably in the range of 99.9: 0.1 to 10:90 by weight. More preferably, it is 99: 1 to 20:80. When the ratio of the inorganic powder and the foaming agent is 99.9: 0.1 by weight, the proportion of the foaming agent becomes smaller, the foaming when insolubilizing the water-soluble binder becomes insufficient, and the bead cannot be expanded sufficiently. . Also, when the ratio of the foaming agent is larger than the ratio of 10:90, the inorganic powder to form the skeleton of the bead becomes smaller, the amount of absorption and adsorption becomes smaller, and as a bead based on the inorganic powder, Characteristics are lost.

In the present invention, the ratio of the water-soluble binder contained in the inorganic powder slurry is 0.
Preferably it is 1 to 5.0% by weight. When the amount of the water-soluble binder is less than 0.1% by weight, the strength of the insolubilized and solidified bead becomes weak, and the bead form may be broken by a small force. The ratio of the water-soluble binder is 5.0
If the amount is more than the weight percentage, the viscosity of the inorganic powder slurry becomes too high, and it may be difficult to drop the inorganic powder slurry.

In the present invention, a powder other than the inorganic powder may be mixed in the porous bead. For example, an organic or inorganic colorant, a thickener, a water-absorbing resin, or an organic or inorganic fiber, cork, wood powder or the like may be mixed with an inorganic powder and contained in the porous bead.

[Effects of the Invention] The porous bead of the present invention has pores communicating with the outside formed by foaming from the inside when the inorganic powder is solidified by the binder. Therefore, not only the outer surface of the bead but also the surface inside the pores can be in contact with the external atmosphere. In particular, when a liquid is to be absorbed and adsorbed as a sustained-release body, the liquid can easily penetrate into the pores, and the substance to be diffused can be adsorbed and adsorbed. Therefore, the speed of absorption and adsorption can be increased, and the amount of absorption and adsorption can be increased as compared with the conventional one.

Further, since the porous bead of the present invention has pores communicating with the outside, even if it has the same apparent volume, the weight is reduced by the amount of the pores formed, which is lighter than the conventional one. become.

The porous bead of the present invention can be used not only as a sustained-release body but also as a catalyst carrier, a bulking agent, or a filler for a separation column, and can be expected to be used in a wide field. The porous bead of the present invention can be appropriately selected from inorganic powders and organic polymers depending on such applications, and the production conditions are changed to change the size and shape of the bead or the diameter of the pore to be formed. And density can be adjusted as appropriate.

[Examples] Examples of the present invention and comparative examples are shown below. Note that the present invention is not limited to the embodiments described below.

Example 1 In a 300 ml polybeaker, 17.5 g of apatite (Ca / P molar ratio 1.67) as inorganic powder, 7.5 g of light calcium carbonate and 50 g of tap water as a foaming agent were used, and using a table-top stirrer (disper). Stir well, mix and disperse,
Under stirring, 25 g of a 2% by weight aqueous sodium alginate solution previously prepared as a binder was further added, and sufficiently stirred and mixed to prepare an inorganic powder slurry.

Then, in another 500 ml glass beaker, 50 g of 36.5% hydrochloric acid
And 50 g of a 10% by weight aqueous solution of calcium chloride and 400 tap water
g was taken and mixed to prepare a binder insolubilizing bath having a pH of 1.2 and a liquid temperature of 30 ° C.

Using a roller pump, the inorganic powder slurry was dropped into the binder insolubilization bath from an orifice with a diameter of 2 mm, foamed and swollen with the carbon dioxide gas generated by the decomposition of carbonate, and scooped the beads floating on the surface of the binder insolubilization bath. I took it.
This was sufficiently washed with water, dehydrated, and dried at 105 ° C. for 4 hours. 4mm diameter, 280ml / 100g apparent volume 20g porous bead
I got

The obtained beads were observed with a scanning electron microscope. First
The figure is a photograph showing the particle structure observed with a scanning electron microscope. FIG. 1 shows a portion of a porous bead 1 photographing unit 2 (shown by hatching in FIG. 2), as shown in FIG. 2, in which pores are formed to reach the outer surface of the porous bead. Is admitted.

Example 2 Apatite (C) was used as an inorganic powder in a 300 ml polybeaker.
a / P molar ratio 1.67) Take 24 g, 1 g of light calcium carbonate and 62.5 g of tap water as a foaming agent, sufficiently stir using a table-top stirrer, mix and disperse, and prepare a binder 2 in advance with stirring. 12.5 g of sodium alginate by weight
Was further added and sufficiently stirred and mixed to prepare an inorganic powder slurry.

Then, in another 500 ml glass beaker, 50 g of 36.5% hydrochloric acid
Then, 50 g of 10% by weight calcium chloride and 300 g of tap water were taken and mixed to prepare a binder insolubilizing bath having a pH of 1.3 and a liquid temperature of 20 ° C.

Using a roller pump made of inorganic powder slurry, the orifice with a diameter of 2 mm is dropped into the binder insolubilization bath, and the beads that have expanded and expanded on the carbon dioxide gas generated by the decomposition of carbonate and floated on the surface of the binder insolubilization bath are scooped. This was thoroughly washed with water, dehydrated, and dried at 105 ° C. for 4 hours. 24 g of a porous bead having a diameter of 5 mm and an apparent volume of 265 ml / 100 g were obtained.

Example 3 In a 300 ml polybeaker, 24.75 g of aluminum hydroxide as an inorganic powder, 0.25 g of copper (I) carbonate as a foaming agent and 62.5 g of tap water were sufficiently stirred using a tabletop stirrer and mixed. 12.5 g of a 2% by weight aqueous sodium alginate solution prepared in advance as a binder with stirring
Was further added and sufficiently stirred and mixed to prepare an inorganic powder slurry.

Then, in another 500 ml glass beaker, 4 g of 96% concentrated sulfuric acid and 1 g
50 g of a 0% by weight aqueous calcium chloride solution and 346 g of tap water were taken and mixed to prepare a binder insolubilizing bath having a pH of 1.2 and a liquid temperature of 25 ° C.

Using a roller pump, inorganic powder slurry was dropped into the binder insolubilization bath from an orifice with a diameter of 2 mm, and the beads floating on the surface of the binder insolubilization bath due to foaming and swelling due to the carbon dioxide gas generated by the decomposition of carbonate were removed. Was. This bead was sufficiently washed with water and dehydrated, and then dried at 105 ° C. for 4 hours. 24.5 g of a porous bead having a diameter of 4 mm and an apparent solution of 300 ml / 100 g was obtained.

Example 4 In a 300 ml polybeaker, calcium silicate (trade name: SOLEX CM; manufactured by Tokuyama Soda Co., Ltd.) 2 as an inorganic powder
4.5 g, 0.5 g ammonium carbonate as a blowing agent and tap water
Take 50 g, sufficiently stir, mix and disperse using a tabletop stirrer, add 25 g of 2% by weight sodium alginate prepared in advance as a binder under stirring, mix well and mix well to obtain inorganic powder slurry. Was prepared.

Then 0.6 g of 36.5% hydrochloric acid in another 500 ml glass beaker
And 50 g of a 10% by weight aqueous solution of calcium chloride and tap water 34
9.4 g was taken and mixed to prepare a binder insolubilizing bath having a pH of 2.0 and a liquid temperature of 80 ° C.

Inorganic powder slurry is dropped into the binder insolubilization bath using a roller pump from an orifice with a diameter of 2 mm, and the beads floating on the surface of the binder insolubilization bath are scooped by foaming and swelling with the carbon dioxide gas generated by the thermal decomposition of carbonate. I took it.
This bead was sufficiently washed with water, dehydrated, and then dried at 105 ° C. for 4 hours. 24 g of a porous bead having a diameter of 5.5 mm and an apparent solution of 510 ml / 100 g were obtained.

Example 5 Calcium as an inorganic powder in a 300 ml polybeaker
24.9 g of magnesium carbonate (trade name: Shirayuka A; manufactured by Shiraishi Industry Co., Ltd.), 0.1 g of zinc carbonate as a foaming agent and tap water 3
Take 7.5 g, sufficiently stir using a tabletop stirrer, mix and disperse, and prepare 5
37.5 g of an aqueous solution of sodium polyacrylate (by weight) was further added, sufficiently stirred, and mixed to prepare an inorganic powder slurry.

Next, 40g of 36.5% hydrochloric acid in another 500ml glass beaker
Then, 10 g of a 10% by weight aqueous zinc chloride solution and 350 g of tap water were taken and mixed to prepare a binder insolubilizing bath having a pH of 0.1 and a liquid temperature of 25 ° C.

Using a roller pump, inorganic powder slurry was dropped into the binder insolubilizing bath from an orifice with a diameter of 2 m, and the beads floating on the surface of the binder insolubilizing bath due to foaming and swelling due to the carbon dioxide gas generated by the decomposition of carbonate were removed. Was. This bead was sufficiently washed with water, dehydrated, and then dried at 105 ° C. for 4 hours. Porous bead 2 with a diameter of 6mm and an apparent volume of 380ml / 100g
4.5 g were obtained.

Example 6 In a 300 ml polybeaker, 5.0 g of nepheline / cyanite (trade name: Minex; manufactured by Indusmin, Canada), 20 g of calcium carbonate and 25.0 g of tap water as a blowing agent were placed in a 300 ml polybeaker. The mixture was sufficiently stirred using, mixed and dispersed, and 50 g of a 10% by weight aqueous solution of sodium carboxymethylcellulose previously prepared as a binder was further added under stirring, and the mixture was sufficiently stirred and mixed to prepare an inorganic powder slurry. .

Next, add 0.35% hydrochloric acid 0.3 in another 500 ml glass beaker.
g and 50 g of a 10% by weight aqueous barium chloride solution and tap water 349.
7 g were taken and mixed to prepare a binder insoluble bath having a pH of 3.5 and a liquid temperature of 30 ° C.

Using a roller pump, the inorganic powder slurry is dropped into the binder insolubilization bath from an orifice with a diameter of 2 mm, and the beads that have foamed and swollen with the carbon dioxide gas generated by the decomposition of carbonate and floated on the surface of the binder insolubilization bath are scooped. I took it.
This bead was sufficiently washed with water, dehydrated, and then dried at 105 ° C. for 4 hours. 24.5 g of a porous bead having a diameter of 4 mm and an apparent solution of 250 ml / 100 g was obtained.

Comparative Example 1 The operation was performed without adding a foaming agent to the inorganic powder slurry and without adding an acid for foaming the foaming agent to the binder insolubilizing bath. In a 300 ml polybeaker, take 25 g of apatite (Ca / P molar ratio 1.67) and 75 g of tap water as inorganic powder, stir well using a table stirrer, mix and disperse, and prepare in advance as a binder with stirring. Further, 12.5 g of a 2% by weight aqueous sodium alginate solution was further added, and sufficiently stirred and mixed to prepare an inorganic powder slurry.

Next, 50 g of a 10% by weight aqueous solution of calcium chloride and 350 tap water were placed in another 500 ml glass beaker and mixed to prepare a binder insolubilizing bath having a pH of 5 and a liquid temperature of 25 ° C.

The inorganic powder slurry was dropped from a 2 mm diameter orifice into a binder insolubilizing bath using a roller pump. The dropped inorganic powder slurry solidified in the binder insolubilizing bath and accumulated on the bottom of the beaker. This was taken out, washed thoroughly with water, dehydrated and dried at 105 ° C. for 4 hours. 24.5 g of a porous bead having a diameter of 3 mm and an apparent volume of 150 ml / 100 g was obtained.

Comparative Example 2 In the same manner as in Comparative Example 1, the same procedure was performed without adding a blowing agent to the inorganic powder and without adding an acid for expanding the blowing agent to the binder insolubilizing bath.

Light calcium carbonate as an inorganic powder in 300 ml of polycarbonate (trade name: Silver W; manufactured by Shiraishi Industry Co., Ltd.)
Take 25 g of tap water and 75 g of tap water, sufficiently stir using a tabletop stirrer, mix and disperse, and prepare a 2 wt% sodium alginate aqueous solution prepared in advance as a binder under stirring.
g was further added and sufficiently stirred and mixed to prepare an inorganic powder slurry.

400 g of a 10% by weight aqueous solution of calcium chloride was placed in another 500 ml glass beaker and mixed to prepare a binder insolubilizing bath having a pH of 4.5 and a liquid temperature of 30 ° C.

The inorganic powder slurry was dropped from a 2 mm diameter orifice into a binder insolubilizing bath using a roller pump. The dropped inorganic powder slurry solidified in the binder insolubilization bath and accumulated on the bottom of the beaker. This bead was taken out by filtration, washed thoroughly with water, dehydrated, and dried at 105 ° C. for 4 hours. 3.5mm diameter porous bead with apparent volume 170ml / 100g
24.5 g were obtained.

Table 1 collectively shows the results of Examples 1 to 6 and Comparative Examples 1 and 2.

Examples 1 to 6 and Comparative Example 1 thus obtained
The characteristics of each of the beads No. 2 and No. 2 as a sustained-release body were evaluated.

First, each bead was immersed in water or a fragrance shown in Table 2 for 5 minutes, then pulled up, and the amount absorbed and retained in each bead was measured. Table 2 shows the results. As is clear from Table 2, Examples 1 to 6 of the beads manufactured according to the present invention show a two to three times absorption retention amount as compared with Comparative Examples 1 and 2, indicating that the beads according to the present invention are porous. The bead was found to be superior as a sustained release body.

Next, similarly, each bead of Examples 1 to 6 and Comparative Examples 1 and 2 was immersed in the citral of the fragrance for 5 minutes and then pulled up. It was measured. As a result, as shown in Table 3, in Comparative Examples 1 and 2, the fragrance was not emitted and the odor was eliminated in about one month, whereas the beads in Examples 1 to 6 according to the present invention had 1 After a month and a half, the odor was still smelling, and the fragrance had been released. As is clear from these results, it was found that the porous bead of the present invention can be used as a sustained-release body and can be emitted for a long period of time, and has desirable properties as a sustained-release body. .

[Brief description of the drawings]

FIG. 1 is a scanning electron micrograph showing the particle structure of a porous bead manufactured according to the present invention. FIG. 2 is a schematic diagram showing a photographed portion of the particle structure shown in FIG. In the figure, reference numeral 1 denotes a porous bead, and 2 denotes a photographing unit.

Claims (2)

(57) [Claims] 1. A porous bead obtained by solidifying an inorganic powder with a binder made of an organic polymer, wherein the porous bead is formed by foaming from the inside when the inorganic powder is solidified with a binder. Formed,
Characterized in that pores leading to the outside are formed,
Porous beads. 2. A method for producing a porous bead containing an inorganic powder, comprising: an inorganic powder slurry containing an inorganic powder, a water-soluble binder and a foaming agent; and an environment for foaming the foaming agent. ,And,
A step of preparing a binder insolubilizing bath containing an insolubilizing agent that insolubilizes the water-soluble binder, and appropriately lowering the inorganic powder slurry in the binder insolubilizing bath while foaming the blowing agent in the inorganic powder slurry. Insolubilizing the water-soluble binder and solidifying it in a bead form.