| 摘要 |
<p>Pressure-rupturable, oil-containing microcapsules are produced by admixing a water-immiscible, oily material containing an oil-soluble, non-polymeric polyfunctional isocyanate cross-linking agent, and an aqueous solution of a polymeric emulsifying agent in the form of a water-soluble polymer containing recurring -NH2 or =NH groups or a water-soluble natural gum containing recurring hydroxy groups. An oil-in-water emulsion is formed containing the isocyanate dispersed in the form of microscopic emulsion droplets in the aqueous continuous phase containing the emulsifying agent, and a solid capsule wall is formed by the cross-linking of the emulsifying agent by the isocyanate. Emulsions utilizing the natural polymeric emulsifying agents preferably contain a viscosity lowering agent in the form of a urea-formaldehyde or alkali metal periodate in order to obtain a higher solids coat weight while at an efficient coating viscosity.</p> |
