Adsorption air filter and method for its production

A method for producing a self-supporting, shaped adsorption air filter, comprising the following steps:

• a) mixing, at room temperature for about 5 minutes:
• 70 to 95 wt % adsorber particles, 5 to 30 wt % binder particles and 15 to 70 wt % water relative to the total mixture of adsorber, binder, and water, said adsorber particles having regular or irregular form with an average size of 100 to 7000 .mu.m, said binder particles having regular or irregular form with an average particle size from 90 to 5% of that of the adsorber particles, the melting range of the binder particles being less than that of the adsorber particles, and the binder not spreading over the adsorber surface below 100.degree. C., wherein a smaller average adsorber particle size is associated with a higher proportion of binder, and wherein the binder particles are a thermoplastic polyurethane having a melting range from 130.degree. to 140.degree. C., the thermoplastic polyurethane having a melting range from 130.degree. to 140.degree. C., the thermoplastic polyurethane including a soft-segment portion of polycaprolactone and a hard-segment portion of 1,4-butanediol and 1,6-hexanediol with diphenylmethane diisocyanage, and between 130.degree. and 180.degree. C. the thermoplastic polyurethane occurs as a highly viscous melt with a viscosity which changes only slightly over the temperature range from 130.degree. to 180.degree. C.;
• b) transferring the mixture, as a loose bulk material, into a cavity of a heatable pressing mold that can be closed pressure-tight and is designed for a pressure load of at least 10.sup.6 Pa;
• c) closing the pressing mold in a pressure-tight manner;
• d) heating the mixture in the closed mold for 5 to 10 minutes to a temperature of at least 100.degree. C. and at least 5.degree. C. above the melting range of the binder, but below the melting range of the adsorber so that the binder particles bind the adsorber particles to form the self-supporting shaped air filter;
• e) decompressing the mold and releasing water vapor from the mold and the shaped air filter;
• f) cooling the shaped air filter to room temperature;
• and
• g) removing the self-supporting shaped air filter from the mold cavity.

A method for producing a self-supporting, shaped adsorption air filter, comprising the following steps:

• a) mixing, at room temperature 70 to 95 wt % adsorber particles, 5 to 30 wt % binder particles and 15 to 70 wt % water relative to the total mixture of adsorber, binder, and water, said adsorber particles having an average size of 100 to 7000 .mu.m, said binder particles having an average particle size from 90 to 5% of that of the adsorber particles, the melting range of the binder particles being less than that of the adsorber particles, and the binder not spreading over the adsorber surface below 100.degree. C., wherein the mixing is done for a sufficient length of time to form a homogeneous mixture, and wherein the binder particles are a thermoplastic polyurethane having a melting range from 130.degree. to 140.degree. C., the thermoplastic polyurethane including a soft-segment portion of polycaprolactone and a hard-segment portion of 1,4-butanediol and 1,6-hexanediol with diphenylmethane diisocyanage, and between 130.degree. and 180.degree. C. the thermoplastic polyurethane occurs as a highly viscous melt with a viscosity which changes only slightly over the temperature range from 130.degree. to 180.degree. C.;
• b) heating the mixture in a pressure tight mold at a temperature of at least 100.degree. C. and at least 5.degree. C. above the melting range of the binder, but below the melting range of the adsorber for a length of time sufficient for the binder particles to bind the adsorber particles to form the self-supporting shaped air filter;
• and
• c) decompressing the mold and releasing water vapor from the mold and the shaped air filter.