JPH0427424A - Microbead and its production - Google Patents

Abstract

PURPOSE:To easily produce microbeads in a short time, in high yield and under mild conditions by flocculating the colloidal fine particles with an electrolyte generating a polyvalent ion of the charge opposite to that of the fine particles. CONSTITUTION:A dispersion (hydrosol) of colloidal fine particles with water as its dispersion medium is dispersed in an oily medium to obtain a W/O emulsion. The colloidal fine particles in the emulsion are flocculated with an electrolyte generating a polyvalent ion of the charge opposite to that of the fine particles to produce microbeads. As this flocculation method, a W/O emulsion is added to an aq. electrolyte soln., or the soln. is added to the emulsion. Any electrolyte generating a polyvalent ion of the charge opposite to that of the colloidal fine particles can be used as the electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to inorganic, organic, or inorganic/organic composite microspheres and a method for producing the same.

[Conventional technology]

The method for producing inorganic microspheres is as follows: After melting the raw material,
Those that form microspheres by spraying a melt, aqueous reaction, and Japanese Patent Publication No. 54-6251, Japanese Patent Publication No. 54-428
73, Special Publication No. 55-37492, Special Publication No. 57-5545
A method of obtaining microspheres by interfacial reaction at the water/oil interface is known, as disclosed in No. 4 and others. On the other hand, although organic microspheres are prepared by suspension polymerization, it is difficult to easily prepare inorganic/organic composite microspheres.

[Problem to be solved by the invention]

In the above method of spraying a melt of the raw material, materials that are unstable at high temperatures cannot be used because they melt at high temperatures.On the other hand, in the case of interfacial reaction, the raw materials used may be strongly alkaline, and the microspheres There may be problems when applying it. Furthermore, it is difficult to combine organic components and inorganic components.

[Means to solve the problem]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems.

That is, the present invention provides: (1) Microspheres obtained by agglomerating colloidal fine particles using an electrolyte that generates multivalent ions having a charge opposite to that of the colloidal fine particles.

(2) A dispersion (hydrosol) of colloidal fine particles using water as a dispersion medium is dispersed in an oily medium to form a W10 type emulsion, and the colloidal fine particles in the emulsion are This invention relates to a method for producing microspheres characterized by agglomeration using an electrolyte that generates multivalent ions having a charge opposite to that of the microspheres.

In the dispersion (hydrosol) of colloidal fine particles using water as a dispersion medium used in the present invention, the particle size of the colloidal fine particles is usually 1000 to 5 nm, preferably 500 to 100 liters.
Onm. Further, as the hydrosol, for example, gold,
Sols of metals such as silver and platinum, silicon oxide, zirconium oxide, aluminum oxide, iron oxide, copper oxide, zinc oxide,
Sols of metal oxides such as chromium oxide, sols of metal sulfides such as arsenic sulfide, zinc sulfide, and lead sulfide, sols of other silver halides, barium sulfate, and ferric hydroxide, and fine particles made of organic polymers. and sols of mixtures thereof. The inorganic sol is manufactured by a known method such as a flocculation method or a peptization method. Further, the organic sol is produced by polymerizing, for example, styrene, methyl (meth)acrylate, vinyl acetate, vinyl chloride, vinylidene chloride, singly or as a mixture, by a known emulsion polymerization method. The solid content concentration of the hydrosol is not particularly limited, and may be within a range that allows easy dispersion of the hydrosol in an oily medium, and is usually 5 to 50% by weight. This hydrosol is dispersed in an organic solvent (oily medium) containing a dispersant to form a W/○ type emulsion. When obtaining inorganic/organic composite microspheres, an inorganic sol and an organic sol may be used together. The organic solvent used here can be any solvent that is generally known as a hydrophobic solvent; for example, as an aliphatic solvent, a hydrocarbon of 06 to CI2, especially n-hexane, n- Butane, n-octane, etc., and aromatic solvents include benzene, toluene,
Commonly used halides include xylene and chlorides, such as chloroform, dichloromethane, tetrachloromethane, and mono- or dichlorobenzene. These solvents may be used alone or as a mixed solvent of two or more. The amount of the organic solvent used is not limited as long as the resulting emulsion is of W2O type, but it is usually 25% by volume or more, preferably 40 to 90% by volume of the emulsion. As dispersants, nonionic surfactants such as polyoxyethylene sorbitan triolate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monostearate can be used. rate, sorbitan triolate,
Turbitan monooleate, sorbitan tristearate, sorbitan monostearate, sorbitan monopalmitate, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, etc., phospholipids such as (hydrogenated) soybean lecithin, (hydrogenated) egg yolk lecithin , and polymer dispersants disclosed in JP-A-56-135501. These may be used alone or in combination of two or more. The amount of the dispersant used is preferably 0.01 to 30% by weight, particularly preferably 0.2 to 20% by weight, based on the hydrosol.

Next, the colloidal fine particles in the obtained W10 type emulsion are aggregated using an electrolyte that generates multivalent ions with a charge opposite to that of the colloidal fine particles.
Obtain microspheres of the present invention. The method for performing this agglomeration is as follows:
For example, methods include adding a W10 type emulsion into an electrolyte aqueous solution, or adding an electrolyte aqueous solution into a W10 type emulsion.

Any electrolyte may be used as long as it generates multivalent ions with a charge opposite to that of the colloidal particles, such as alkaline earth metals, iron, cobalt, nickel, copper, and zinc. , chlorides, bromides, nitrates, and sulfates such as aluminum, and polymer electrolytes such as polyacrylic acid, polystyrene sulfonic acid, and chitosan.

The amount of electrolyte to be used should be sufficient to coagulate colloidal particles.
(However, in the case of a polymer electrolyte, 0.1 to 5% by weight) of an aqueous electrolyte solution is preferably used in an amount of 5 to 500% by volume based on the W10 type emulsion.

The temperature at which the method of the present invention is carried out is not particularly limited as long as it does not damage the dispersion system, and it can usually be carried out at 20 to 70°C.

Add W10 type emulsion into the electrolyte aqueous solution, or
When adding the electrolyte aqueous solution to the W10 emulsion, the rate of addition is not particularly limited as long as the rate does not break the emulsion.

In this way, the microspheres of the present invention are obtained in the form of a slurry. When making powdered microspheres from this, there are no particular restrictions on the method, and any conventional method can be used. For example, it can be obtained by washing a microsphere slurry with alcohol and water, separating solid and liquid by suction filtration, and drying. Alternatively, powdered microspheres can be obtained directly by a spray drying method or the like.

The particle size of the microspheres obtained in the present invention is determined by the dispersion conditions of the W10 emulsion, and usually particles with a particle size of 1 to 500 μm are obtained. That is, microspheres with a desired particle size can be obtained by selecting the type and amount of the dispersant used and the stirring conditions (diameter of stirring blades, rotation speed, etc.).

As described above, according to the method of the present invention, desired microspheres can be obtained in high yield under mild conditions and with easy operation and in a short time. The microspheres of the present invention can be used as fillers for plastics and composite materials, carriers for various materials, and the like.

〔Example〕

In the examples, the number in parentheses after the amount obtained indicates the proportion of colloidal fine particles used that became microspheres.

Example 1 Colloidal silica (5iOz, Snowtex 01 particle size 10-20nm, solid concentration 20%) 8- was dissolved in chloroform 24m containing sorbitan triolate o, tg, polyoxyethylene sorbitan monooleate, 1.0g.
Disperse using a homogenizer (9000rl)
m.

30 seconds) Prepare a W10 emulsion. Next, put 50% of a 20wt% calcium chloride aqueous solution in a 200rnl round bottom flask equipped with a stirrer, and add about 50% of the emulsion while stirring.
Drip over several minutes. Continue stirring at room temperature for 30 to 60 minutes. Add 20 ml of methanol to the obtained slurry, filter it with suction to remove microspheres, and dry. The average particle size of the obtained powder microspheres was 1% 1 m, and the yield was 1.4 g (8
7.5%).

Example 2 Colloidal silica (5i02, Snowtex 0, particle size 10-20 nm, solid content concentration 20%) 16- was dissolved in 48 m of chloroform in which 0.1 g of sorbitan triold and 1.0 g of polyoxyethylene sorbitan monooleate were dissolved.
1 using a homogenizer at 9000 rpm,
30 seconds) Prepare a W10 emulsion. This was placed in a 300 ml round bottom flask equipped with a stirrer, and a 10 wt % aqueous calcium chloride solution 24- was added dropwise over about 5 minutes while stirring. Continue stirring at room temperature for 15 to 30 minutes. 201 nl of methanol is added to the obtained slurry, microspheres are separated by suction filtration, and the slurry is dried. The average particle size of the obtained powder microspheres was 11 μm, and the amount obtained was 3.0 g (9
4%).

Example 3 Zirconia sol (Zr02, NZS-3OA, Yasan Kagaku Co., Ltd., particle size 95 nm, solid content concentration 35%) 16
Using a homogenizer, disperse the mixture into 48% methylene chloride in which 0.2g of sorbitan triolate and 1.5g of polyoxyethylene sorbitan monooleate were dissolved.
0rpm.

20 seconds) Prepare a W10 emulsion. This was placed in a 300 mt7 round bottom flask equipped with a stirrer, and while stirring, a 15 wt % aqueous sodium sulfate solution 24 was added dropwise over about 5 minutes. Continue stirring at room temperature for 15 to 30 minutes. Add 201 nl of methanol to the obtained slurry, filter out the microspheres by suction filtration, and dry. The average particle size of the obtained powder microspheres was 23 μm, and the yield was 5.1 g (91%).
Met.

Example 4 Alumina sol (Ai20s, colloidal alumina-10
0, particle size 420nm, solid content concentration 15%) 10mt
'Polyoxyethylene sorbitan monooleate 0.1
6 g of sorbitan monostearate and 0.48 g of sorbitan monostearate were dissolved in 30 mN of toluene using a magnetic stirrer for 2 minutes to prepare a W10 type emulsion. This was placed in a 200 mtF round bottom flask equipped with a stirrer, and 15 m&' of a 10 wt % sodium nosulfate aqueous solution was added dropwise over about 5 minutes while stirring. Continue stirring at room temperature for 15 to 30 minutes. Add 20 methanol to the obtained slurry, filter out the microspheres by suction filtration, and dry. The average particle size of the powder microspheres obtained was 18 μm, and the yield was 1.2 g (88°9
%)Met.

Example 5 Styrene latex (particle size 120 nm, solid content concentration 3
Disperse 0.1 g of polyoxyethylene sorbitan monoolet (0.1 g) and 0.5 g of sorbitan triolate using a homogenizer (7000 rpm, 30 seconds) to prepare an emulsion. Transfer this to a 200mm round bottom flask equipped with a stirrer, and without stirring, add 30rnI of a 10wt% aluminum sulfate aqueous solution.
Add it dropwise over about 5 minutes. Continue stirring at room temperature for 15 to 30 minutes. Add methanol to the resulting slurry for 20 minutes.
- In addition, the microspheres are filtered off using suction filtration and dried. The average particle size of the obtained powder microspheres was 45 μm, and the amount obtained was 4.1
g (91%).

Example 6 Colloidal silica (SiOz, Snowtex 0, particle size 10-20 nm, solid content concentration 20%) 7.5 mt', styrene latex (particle size 35 nm, solid content concentration 10%)
7.5- Polyoxyethylene sorbitan monooleate O, Ig.

Disperse 0.5 g of sorbitan olaryle in hexane 45-45 using a homogenizer at 8000 rpm.
30 seconds) Prepare the emulsion. Add this to the 20 with a stirrer.
Transfer to a 0rnl round bottom flask and add 10wt without stirring.
% aluminum sulfate aqueous solution was added dropwise over about 5 minutes. Continue stirring at room temperature for 15 to 30 minutes.

207 ni of methanol is added to the obtained slurry, microspheres are filtered off by suction filtration, and the slurry is dried. The average particle size of the obtained powder microspheres was 24 μm, and the yield was 1.9 g (84.4%
)Met.

Example 7 Zirconia sol (ZrOz, NZS 30A,
Particle size 95 nm, solid content concentration 35%) 10 mj), alumina sol (A1202, colloidal alumina-100, particle size 420 nm, solid content concentration 15%) 6 mj), sorbitan triolate 0.2 g, polyoxyethylene sorbitan monooleate 1.5 g Methylene chloride dissolved in 48-
using a homogenizer at 7000 rpm,
20 seconds) - Prepare W10 type emulsion. Next, a 10 wt % aqueous sodium sulfate solution (120 mm) was placed in a 300 mm round bottom flask equipped with a stirrer, and the emulsion was added dropwise over about 5 minutes while stirring.

Continue stirring at room temperature for 30 to 60 minutes. Add 201d of methanol to the resulting slurry! In addition, microspheres are filtered out by suction filtration and dried. The average particle size of the powder microspheres obtained was 85 μm, and the yield was 3.9 g (88.6%).

Example 8 Colloidal silica (SiO□Snowtex 0, particle size 1
0-20 nm, solid content concentration 20%) 16-, 0.1 g of sorbitan triolate, 1.0 g of polyoxyethylene sorbitan monooleate. Using a homogenizer, disperse Og in chloroform (48 mm) at 9000 rpm for 3 hours.
0 seconds) Prepare a W10 type emulsion. Transfer this to a 300-mm round bottom flask equipped with a stirrer, and while stirring,
A 30-wt% chitosan aqueous solution is added dropwise over about 5 minutes.

Continue stirring at room temperature for 15 to 30 minutes.

20 ml of methanol is added to the obtained slurry, microspheres are separated by bow filtration, and the slurry is dried. The average particle size of the obtained powder microspheres was 21 μm, and the yield was 2.8 g (87.5%)
Met.

Example 9 Colloidal silica (S102 Snowtex 0, particle size 1
0 to 20 nm, solid content concentration 20%) 8- is dispersed in 24 ml of chloroform in which 30 mg of sorbitan monopalmitate and 3 mg of soybean lecithin are dissolved using a homogenizer (8000 rpm, 30 seconds) to prepare a W10 type emulsion.

Transfer this to a 300-inch round bottom flask equipped with a stirrer,
While stirring, a 10 wt % aqueous calcium chloride solution 12- is added dropwise over about 5 minutes. Continue stirring at room temperature for 15 to 30 minutes. Add 201 methanol to the resulting slurry.
Add nI, filter out the microspheres by suction filtration, and dry. The average particle size of the obtained powder microspheres was 30 μm, and the yield was 1.5
g (93.7%).

〔Effect of the invention〕

The microspheres of the present invention can be produced in a short time and in high yield under mild conditions and easy operations, and are applied to fillers for plastics and composite materials, carriers for various materials, and the like.

Patent applicant: Nippon Kayaku Co., Ltd.

Claims (1)

[Claims] 1. Microspheres obtained by agglomerating colloidal fine particles using an electrolyte that generates multivalent ions with a charge opposite to that of the colloidal fine particles. 2. A dispersion (hydrosol) of colloidal fine particles using water as a dispersion medium is dispersed in an oily medium to form a W/O emulsion, and the colloidal fine particles in the emulsion are A method for producing microspheres characterized by agglomeration using an electrolyte that generates multivalent ions with a charge opposite to that of the microspheres.