| 摘要 |
Microcapsules are produced in-situ in a film or during the manufacturing process of a water-based coating composition from which the film is formed. A principal process involves the in-situ production of void-containing microcapsules in a film formed from a water-based coating. This principal process involves as a first step the preparation of a polymer composition which may be a homogeneous solution containing a water-immiscible organic polymer, a water-immiscible solvent for the polymer, and a water-immiscible lower volatility non-solvent which is miscible with the solvent; or an emulsion containing as the continuous phase a water-immiscible organic polymer dissolved in a water-immiscible solvent for the polymer and, as the discontinuous phase, droplets of a lower volatility non-solvent dispersed in the continuous phase. This polymer composition is then emulsified under agitation and in the presence of a surfactant into a water-based coating composition. The water-based coating composition containing this emulsified polymer composition is then applied to a substrate and the solvent is evaporated from the polymer composition to produce microcapsules containing discrete droplets of the non-solvent. Subsequent drying of the water-based coating and evaporation of the non-solvent from the microcapsules produces a film having incorporated therein structured, closed-cell, void-containing microcapsules with the voids serving to provide opacity and gloss control to the film. In an alternative to the principal process, microcapsules containing the non-solvent are produced in-situ in the water-based coating composition prior to forming a film therefrom.
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