Method for producing an aqueous dispersion of silica capsule particles

Abstract

This invention relates to a method for producing an aqueous dispersion of silica capsule particles that exhibits excellent corrosion suppression properties for manufacturing equipment and has low viscosity. [Solution] A method for producing an aqueous dispersion of silica capsule particles having a core containing a functional agent and a shell containing silica as a constituent component, comprising the following steps 1, 2, and 3 in this order. Step 1: A process to obtain an aqueous dispersion containing silica capsule particles having a core containing a functional agent and a shell containing silica as a constituent component, by subjecting an emulsion containing a halogen atom, a cationic surfactant, water, a functional agent, and a silica precursor to a sol-gel reaction under acidic conditions. Step 2: The aqueous dispersion obtained in Step 1 is subjected to anion exchange treatment to reduce or remove halide ions in the aqueous dispersion, thereby obtaining an aqueous dispersion. Step 3: A step to obtain an aqueous dispersion of silica capsule particles by adjusting the pH of the aqueous dispersion obtained in Step 2 to 4.0 or lower.

Claims

1. A method for producing an aqueous dispersion of silica capsule particles having a core containing a functional agent and a shell containing silica as a constituent component, comprising the following steps 1, 2, and 3 in this order. Step 1: A step in which an emulsion containing a cationic surfactant containing halogen atoms, water, a functional agent, and a silica precursor is subjected to a sol-gel reaction under acidic conditions to obtain an aqueous dispersion containing silica capsule particles having a core containing a functional agent and a shell containing silica as a constituent component. Step 2: A step to obtain an aqueous dispersion obtained by anion exchange treatment of the aqueous dispersion obtained in Step 1, thereby reducing or removing halide ions in the aqueous dispersion. Step 3: A step to obtain an aqueous dispersion of silica capsule particles by adjusting the pH of the aqueous dispersion obtained in Step 2 to 4.0 or lower.

2. A method for producing an aqueous dispersion of silica capsule particles according to claim 1, wherein the anion exchange treatment in step 2 is a method of contacting the aqueous dispersion obtained in step 1 with an anion exchange resin.

3. The method for producing an aqueous dispersion of silica capsule particles according to claim 2, wherein in step 2, the amount of anion exchange resin added to 1 mmol of halide ions in the aqueous dispersion obtained in step 1 is 0.5 g or more.

4. A method for producing an aqueous dispersion of silica capsule particles according to claim 1 or 2, wherein the concentration of halide ions in the aqueous dispersion obtained in step 2 is 20 ppm by mass or less.

5. A method for producing an aqueous dispersion of silica capsule particles according to claim 1 or 2, wherein the viscosity of the aqueous dispersion of silica capsule particles at 25°C is 10 mPa·s or less.

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