Microcapsule suspension liquid and process for production thereof
An aqueous microcapsule suspension liquid exhibiting an excellent (long-term) storage stability and allowing easy re-dispersion and dilution with water even after such a storage, is produced by adding a microorganism-fermented polysaccharide of succinoglycan type as a thickening agent into a microcapsule slurry, or by adding such a microorganism-fermented polysaccharide as a thickening agent to a microcapsule slurry after uniform dilution with water.
1. A process for producing a microcapsule suspension liquid, comprising:
(I) a step of mixing a thickening agent comprising a microorganism-fermented succinoglycan polysaccharide and propylene glycol for dilution with water to form a dilute thickening agent aqueous solution,
(II) a step of dispersing microcapsules comprising a core material and a resinous coating in an aqueous medium to form a microcapsule slurry, and
(III) a step of mixing the above-formed microcapsule suspension liquid with the above-formed dilute thickening agent aqueous solution, followed by addition thereto of sodium polyacrylate and an anti-foaming agent comprising silicone,
wherein the microcapsules have a resinous coating layer comprising a successive laminate including a solidified layer of coacervate of a water-soluble cationic amino resin and an anionic surfactant and a layer of polycondensate of amino resin prepolymer,
obtained through a process comprising a step of mixing the core material and an anionic surfactant aqueous solution and then with a pH-adjusted aqueous solution of the water-soluble cationic amino resin to coat the core material with the coacervate of the water-soluble cationic amino resin and the anionic surfactant, a step of mixing the coacervate-coated core material with an amino resin prepolymer liquid, and a step of adding an acidic catalyst to polycondense the amino resin prepolymer, and
in the step (I), the thickening agent is first mixed and dispersed together with the propylene glycol, and then is diluted with water to form the dilute thickening agent aqueous solution.