JPS63270306A - Porous inorganic substance fine particle and production thereof - Google Patents

Abstract

PURPOSE:To obtain the titled spherical fine particles useful in coating compound, printing ink, spacer for liquid crystal or carrier for enzyme immobilization, by blending an aqueous solution of an alkali metal silicate with an organic solvent in the presence of a nonionic surface active agent to give a W/O type emulsion and adding an aqueous solution of a specific compound to the W/O type emulsion. CONSTITUTION:An aqueous solution of an alkali metal silicate having 0.5-6mol./l SiO2 concentration is blended with organic solvent such as n-hexane, ethyl acetate or benzene in the presence of a nonionic surface active agent such as preferably polyoxyethylene alkyl aryl ether and stirred at high speed to give a W/O type emulsion having the ratio of W/O of 4/1-1/5. Then the emulsion is blended with an aqueous solution of one or more compounds which are selected from alkaline earth metallic halides, inorganic acids, organic acids, NH4 salts of these acids and bicarbonates of alkali metal and are capable of reacting with an alkali metal silicate to give a compound of silicic acid type and reacted at normal temperature-under heating at normal pressure for <=1hr to give the titled fine particles having <=2mu maximum particle diameter, <=1mu average particle diameter, consisting essentially of the compound of silicic acid type such as alkaline earth metallic silicate.

Description

DETAILED DESCRIPTION OF THE INVENTION 11) The present invention relates to porous inorganic fine particles and a method for producing the same, and more particularly to porous inorganic fine particles having a particle size of 2 μm or less and a method for producing the same.

Conventional technology One of the conventional manufacturing methods for inorganic porous powder and granular materials.
The method of Patent No. 1184016 is known. This method involves adding an organic solvent to an aqueous solution containing at least one inorganic compound selected from silicates, carbonates, phosphates, and nitrates of alkali metals, and halides of alkali metals and other metals. Add and mix to form an emulsion, and then add at least one of alkaline earth metal halides, inorganic acids, organic acids, ammonium salts of non-IN acids, ammonium salts of organic acids, and carbonates and nitrates of alkali metals. Then, an aqueous solution of a compound capable of forming a water-insoluble precipitate through an aqueous reaction with the inorganic compound is mixed with the emulsion to produce porous inorganic fine particles.

This method is the fourth method for producing inorganic porous particles, but in this method,
Particularly small particle size, for example, 2 μm
In the following, it is not intended to actively produce fine particles having an average particle diameter of 1 μm or less.

Problems to be Solved by the Invention Accordingly, the problems to be solved by the present invention are that inorganic porous fine particles having a particle size of 2 μm or less can be actively produced by applying the technology of this type of conventional method. The goal is to develop methods.

Means for solving the problem The problem is that the degree of 5tO2 is 0.5 to 6 mol/l.
An organic solvent is added and mixed to an aqueous alkali metal silicate solution in the coexistence of a nonionic surfactant to give a W/O ratio of 4/1 to 4/1.
A W10 type emulsion of No. 115 was prepared, and then at least one of an alkaline earth metal halide, an inorganic acid, an organic acid, an ammonium salt of an inorganic acid, an ammonium salt of an organic acid, and an alkali metal bicarbonate was prepared. This problem is solved by mixing into the emulsion an aqueous solution of a compound capable of forming a silicic acid compound through an aqueous reaction with the alkali metal silicate.

Structure and operation of the invention The major features of the method of the present invention are as stated above: (a)
As an aqueous alkali metal silicate solution, especially SiO
(b) The surfactant is a nonionic surfactant, particularly preferably polyoxyethylene alkylaryl. (c) using a needle surfactant; (c) setting the W/O ratio of the emulsion to 4/1 to 115, preferably 2/1 to 1/2; (d) more preferably emulsion preparation. The purpose of stirring is to use high-speed stirring.

That is, by using the above-mentioned means (a) to (c), more preferably (d), it is possible to produce very small particles with a particle size of 2 μm or less and an average particle size of 1 μm or less. It can be manufactured. In this case, the above (
If any one of the requirements from (a) to (c) is not satisfied, use the specific fine particles listed above! IJ construction is not possible.

The method of the present invention will be explained below in the order of its manufacturing steps.

First, an alkali metal silicate aqueous solution, preferably its sho,
The concentration of is 0.5 to 6.0 mol/, preferably 2.0 to 6.0
A W10 type emulsion is prepared by adding and mixing a 4.0 mol/Q aqueous solution to an organic solvent using a nonionic surfactant. As the organic solvent, those conventionally used can be used, and preferred ones include those that are liquid at room temperature, have a solubility in water of 8% or less, and do not substantially participate in the reaction.

Preferred specific examples of these are as follows.

Aliphatic hydrocarbons: n-hexane, isoheginane, n-hebutane, isohebutane, n-octane, isooctane, gasoline, petroleum ether, kerosene, benzine, mineral spirit, etc. Alicyclic hydrocarbons: cyclopentane, Aromatic hydrocarbons such as cyclohexane, cyclohexene, and cyclononane: Benzene, triene, xylene, ethylbenzene, propylbenzene, cumene, mesitylene, tetralin, styrene, etc. Ethers: Probyl ether, isopropyl ether, etc. Halogenated hydrocarbons: Methylene chloride, Chloroform, ethylene chloride, trichloroethane, trichloroethylene, etc., esters: ethyl acetate, 111-n-propyl acid, isopropyl acetate, -butyl acetate, isobutyl acetate, -amyl acetate, isoamyl acetate, butyl lactate, methyl propionate , edyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, etc. These organic solvents can be used alone or in combination of two or more.

When preparing this W/O”r! emulsion, the W/O ratio of the emulsion obtained is 4/1 to 115, preferably 2/
It should be about 1 to 1/2. The amount of surfactant used is preferably about 10% or less of the organic solvent, particularly 0.1 to 3mf.
Approximately f1% is preferable. During this emulsification, it is preferable to perform stirring at high speed, thereby making it easier to obtain finer particles.

As the surfactant used, a nonionic surfactant is used, and preferred specific examples are as follows.

Polyoxyethylene sorbitan fatty acid esters: polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, Polyoxyethylene sorbitan stearate, etc. PolyA xyethylene higher alcohol ethers: polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene nonylphenol ether, polyoxyethylene nonylphenol Ether, etc. Polyoxyethylene fatty acid ester type: polyoxyethylene glycol monolaurate, polyoxyethylene glycol monostearate, polyoxyethylene glycol stearate, polyoxyethylene glycol monooleate, etc. Glycerin fatty acid ester type nistearic acid monoglyceride , oleic acid monoglyceride, etc., polyoxyethylene sorbitol fatty acid ester type: tetraoleic acid polyA xyethylene sorbitol, etc. Among these surfactants, polyoxyethylene alkyl allyl ether type surfactants are particularly preferred; They may be used alone or in a mixture of two or more.

Next, in the present invention, an aqueous solution of a compound capable of reacting with an alkali metal silicate to form a silicic acid compound is added to and mixed with the W10 type emulsion to cause the reaction to form a silicic acid compound as a wall material. .

Although this reaction proceeds well at normal temperature and normal pressure, the reaction may be accelerated under heating. The reaction time varies depending on the concentration and blending ratio, but is usually about 1 hour or less. The concentration of the aqueous solution is preferably 0.05 mol/l to saturation concentration, particularly preferably about 0.1 to 2 mol/l.

Porous inorganic fine particles are obtained by filtering the reaction product, washing with water, and drying. The compounds that can form the silicic acid compound used in this case include at least one of alkaline earth metal halides, inorganic acids, organic acids, ammonium salts of inorganic acids and organic acids, and alkali metal heavy carbon WI salts.
Various types of seeds that have been used conventionally are used. The porous inorganic fine particles obtained by the method of the present invention are extremely fine particles in which the maximum diameter of a single particle is 2 μm or less, and the average particle size of the entire aggregate of many particles is 1 μm or less, and the particles themselves is formed from a porous wall material. There are also some that are hollow inside. Typical examples of the silicic acid compound forming the wall material include silicates of alkaline earth metals and alkali silicates, and more specifically, calcium silicate, magnesium silicate, barium silicate, and the like.

Effects of the Invention By the method of the present invention as described above, spherical porous fine particles having a particle diameter of 2 μm or less can be obtained. This product is extremely useful for paints, printing inks, spacers for liquid crystals, carriers for immobilizing enzymes and microorganisms, and fat films.

Example The present invention will be explained in more detail with reference to Examples below.

Example 1 (Production method of porous spherical microsilica) Water gas 7 s 15'J (SiO:, I:-SiT: 4 mol/fJ, > 200d, polyoxyethylene (n-
10) A W10 emulsion was prepared by mixing 100 d of a 2% lauryl ether solution in ethyl acetate and stirring at high speed.

1 q of the W10 type emulsion thus prepared was added to 3000 d of a 1 mol/cross ammonium sulfate aqueous solution, stirred and reacted, left for 2 hours, filtered and separated, washed with water and dried to form a porous material with a particle size of 2 μm or less. Spherical silica particles, 48
(I got +.

Example 2 (Production method of porous spherical microscopic calcium silicate) 200 d of water glass No. 4 (2 mol/cross as Si Oλ) and 200 ml of a 3% toluene solution of polyoxyethylene (n = 4>'A rail ether) were mixed. A W10 type emulsicon was prepared by stirring at high speed.

The W10 type emulsion thus obtained was added to 2000 m of the chloridizing power/lucium aqueous solution, stirred and reacted, left for 2 hours, separated by filtration, washed with water and dried to form porous particles with a particle size of 2 μm or less. 46 g of fine spherical calcium silicate particles were obtained.

Example 3 (Production method of porous spherical microscopic barium silicate) Potassium silicate (
300 Idl as SiO (3 mol/dichloromethane) and polyoxyethylene (n-6) secondary alcohol (C, ri,
~14) A W10 type emulsion was prepared by mixing 0.5% ether with 600% n-hexane solution and stirring at high speed.

The W10 type emulsion thus obtained was added to 2000 td of a 1 mol/s barium chloride aqueous solution, stirred, allowed to react for 1 hour, separated by filtration, washed with water and dried to form porous spheres with a particle size of 2μ or less. Barium silicate fine particles 190
9 is 19.

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Claims (8)

[Claims] (1) The particle size is 2μ, which is mainly composed of silicic acid compounds.
Porous inorganic fine particles with a size of less than m. (2) The porous inorganic fine particles according to claim 1, which have an average particle size of 1 μm or less. (3) The porous inorganic fine particles according to claim 1 or 2, which are hollow inside. (4) Porous inorganic fine particles according to claim 1, wherein the silicic acid compound is an alkaline earth metal silicate. (5) Add and mix an organic solvent to an aqueous alkali metal silicate solution with a SiO_2 concentration of 0.5 to 6 mol/l in the coexistence of a nonionic surfactant to achieve a W/O ratio of 4/1 to 1. /5 W/O emulsion is prepared, and then at least one of alkaline earth metal halides, inorganic acids, organic acids, ammonium salts of inorganic acids, ammonium salts of organic acids, and bicarbonates of alkali metals is prepared. A method for producing porous inorganic fine particles, which comprises mixing into the emulsion an aqueous solution of a compound which is a seed and can form a silicic acid compound through an aqueous reaction with the alkali metal silicate. (6) The nonionic surfactant has a polyoxyethylene sorbitan fatty acid ester type, a polyoxyethylene higher alcohol ether type, a polyoxyethylene fatty acid ester type, a glycerin fatty acid ester type, and a polyoxyethylene sorbitol fatty acid ester type surfactant. The method for producing porous inorganic fine particles according to claim 4, wherein the porous inorganic fine particles are at least one type of agent. (7) The method for producing a porous inorganic material according to claim 4 or 5, characterized in that the emulsion is prepared under high-speed stirring. (8) The method for producing porous inorganic fine particles according to any one of claims 4 to 7, wherein the amount of the nonionic surfactant is 10% by weight or less based on the organic solvent.