This may be the pulp connection to the Polyurethane filter. Filtering face-piece respirator having a face seal comprising a water-vapor-breathable layer Paten

This may be the pulp connection to the Polyurethane filter. Filtering face-piece respirator having a face seal comprising a water-vapor-breathable layer Patent Assignee 3M INNOVATIVE PROPERTIES COMPANY (St. Paul, MN, US) http://www.freepatentsonline.com/9408424.html http://www.freepatentsonline.com/9408424.html In discussing a way to take water vapour from exhaled breath away from the filter surface. If this is the case while the polyurethane is the primary material the pulp fibre is applied to it as a layer which may not appear in a spec sheet. "In some embodiments, a face seal may consist only of a water-vapor-breathable layer and a wicking layer (that is located on the rearward side of at least a portion of the water-vapor-breathable layer), with no other layers being present. In other embodiments, other layers may be present in the face seal. There are several general approaches to providing such a wicking layer, which approaches will be described herein in a non-limiting manner. In one approach, a fibrous wicking layer (e.g., a non-woven web, a woven or knitted fabric, and so on) can be comprised (e.g., generally, substantially, or completely) of fibers with “moderate” hydrophilicity. Materials that might be suitable for such fibers include e.g. certain nylons, polyesters, cellulose acetates, and so on. In another approach, a fibrous wicking layer can be comprised of relatively hydrophobic fibers (e.g., polyethylene, polypropylene, natural rubber, and so on), but with the web incorporating some portion of relatively hydrophilic fibers (e.g., cellulosic fibers, acrylic fibers comprising a significant amount of hydrophilic co-monomer, and so on). That is, any suitable blend of hydrophobic fibers and hydrophilic fibers can be used to arrive at the optimum balance of properties. In a variation of such approaches, a fibrous wicking layer can be comprised of relatively hydrophobic fibers but may further comprise hydrophilic particles of any suitable composition (e.g. hydrocolloids, WOOD PULP, starch particles, and so on). Conversely, a fibrous wicking layer can be comprised of relatively hydrophilic fibers but may further comprise hydrophobic particles of any suitable composition."