US 4,828,542 · Granted 1989-05-09

Foam substrate and micropackaged active ingredient particle composite dispensing materials

A new composite material of an open foam substrate and bonded micropackaged active ingredient particles is generated by foam polymerization of a prepolymer phase and an aqueous phase. The foam substrate is an open cell foam for dispensing active ingredient liquids or solids released from the particles. The particles of micropackaged active ingredient liquids or solids are formed with frangible containment walls for breaking and releasing the active ingredient in response to defined stress. The micropackaged active ingredient particles are approximately 400 to 5,000 microns in diameter. The aqueous phase is a pourable and flowable slurry mixture of an aqueous liquid carrier such as water, micropackaged active ingredient particles in the range of 1%-60% by weight of the aqueous phase, and surfactant wetting agent for adjusting the surface tension of the aqueous phase to produce an open cell foam upon polymerization with the prepolymer phase. The prepolymer phase is a hydrophilic polyurethane prepolymer receptive to the aqueous phase for foam polymerization upon mixing. The aqueous phase and prepolymer phase are generally mixed together in a ratio by weight of aqueous phase to prepolymer phase in a range of at least approximately 0.02/1 or greater and preferably 1/1 or greater. Upon foam polymerization, the active ingredient particles are distributed over and intimately bonded to the surfaces of the open foam substrate. The micropackaged particles may constitute any of the available microcontainment systems including microencapsulation system microcapsules and entrapment system microlattices.

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