Adsorption filter for air and process for preparing it

摘要

An adsorption air filter consists of a self-supporting shaped structure of regular or irregular adsorption particles linked to a binding agent of regular or irregular consistency. The hot-melt range of the binding agent particles is smaller than that of the adsorption particles and that the former are smaller than the latter, and have a median size of 100 to 7000 mu m. The novelty is that the air filter structure consists spatially in essence of a repeated sequence adsorbent particles and a binding agent particle and that no agglomerated structures can be detected by the naked eye. The binding agent may not spread on the adsorbent surface at temperatures less than 100 degrees C. The air filter is made by mixing the adsorbent particles and binding agent with water. The mixture is heated under pressure in a sealed form, expelling the water, and then cooling in the form. The binding agent particles are thermoplastic polyurethane with a hot-melt range of from 130 to 140 degrees C. Between 130 and 180 degrees C the binding agent has almost no change in its high viscosity. It is formed by a combination of a soft segment of polycaprolactone and a hard segment of 1,4-butandiol and 1,6-hexandiol with diphenyl-methane-d i-isocyanate.