Composite active filter material

A method for producing an active filter material comprising:

• preparing an aqueous phase comprising a pourable slurry mixture by mixing active surface particle powder and surfactant wetting agent means in sufficient aqueous liquid carrier to provide a pourable aqueous phase comprising approximately 15% to 50% by weight of the active surface particle powder and soaking the active surface particle powder to provide a protective liquid layer or barrier over the active surfaces of the powder particles;
• mixing the aqueous phase in substantially equal or greater proportion by weight with a prepolymer phase comprising a hydrophilic urethane NCO-terminated prepolymer receptive to the aqueous phase so that the mixture is initially pourable and flowable, said aqueous phase and prepolymer phase being mixed together in ratio by weight in the range of approximately 1/1 to 8/1, and foam polymerizing the aqueous phase and prepolymer phase thereby providing an open hydrophilic foam substrate and bonded active surface particle powder composite with the active surface powder particles distributed over and bonded to the surfaces of the open hydrophilic foam substrate;
• and evaporating the protective liquid layer over the active surfaces of the powder particles by drying the resulting composite whereby the active surfaces of the powder particle material are exposed for active filter functioning.

A method for producing an active filter material comprising:

• preparing an aqueous phase comprising a pourable and flowable slurry mixture by mixing active surface particle powder and surfactant wetting agent means in sufficient water to provide a pourable aqueous phase comprising approximately 15% to 50% by weight of active surface particle powder and soaking the activated surface particle powder to provide a protective liquid layer or barrier over the active surfaces of the powder particles;
• mixing the aqueous phase in substantially equal or greater proportion by weight with a prepolymer phase comprising a hydrophilic urethane NCO-terminated prepolymer receptive to the aqueous phase, so that the mixture is initially pourable and flowable, and foam polymerizing the aqueous phase and prepolymer phase thereby providing a reticulated hydrophilic foam substrate and bonded active surface particle powder composite with the active surface powder particles distributed over and bonded to the webs of the hydrophilic foam substrate;
• and evaporating the protective liquid layer from the active surfaces of the powder particles by drying the resulting composite and exposing the major portion of the active surfaces of the powder particles for active filter functioning.