Patent DE-29924500-U1 (DE)
Title: Disposable filter bag for vacuum cleaners
IPC: B01D39/18
Filed: 1999-05-11
Abstract: A coarse filter layer comprises at least one of a wet-laid high capacity paper, dry-laid high capacity paper, high bulk melt blown non woven, a spun blown (modular) non woven, a micro denier spun-bond non woven positioned upstream in the direction of air flow of a filtration grade melt blown fleece. The basis weight and air permeability of filtration grade melt blown fleece layer, wet-laid high dust capacity layer, dry-laid high dust capacity paper and high bulk melt blown non woven are 10-50 g/m 2> and 100-1500 L/(m 2>s), 30-150 g/m 2> and 500-8000 L/(m 2>s), 30-150 g/m 2> and 500-8000 L/(m 2>s) and 30-180 g/m 2> and 300-8000 L/m 2>s respectively. The downstream of the filtration grade melt blown fleece layer has an outer layer comprising at least one of a spun-bond, wet-laid, dry-laid or hydroentangled non woven or netting with basis weight of about 6-80 g/m 2> and air permeability of about 500-10000 L/m 2>s and an odor absorbing composite comprising an activated carbon fiber layer having a basis weight of about 25-500 g/m 2> and air permeability of about 500-3000 L/m 2>s. Upstream of a backing layer of fleece has a basis weight of 15-100 g/m 2> and air permeability of 2000-5000 L/m 2>s. To the upstream of the coarse filter layer is the support layer which is one of a netting scrim bonded to the coarse filter layer, a wet-laid tissue fleece, spun bond non woven. The coarse filter layer material has suitable dielectric properties and is electrostatically charged. One layer is bonded to its adjacent layer with a porous hot melt adhesive. The dry-laid high capacity paper comprises bicomponent fibers with a sheath of polyethylene and a core of polypropylene having a melting point higher than the sheath. The core is disposed eccentric relative to the sheath. Alternatively, a multipurpose filtration capacity layer positioned upstream in the direction of air flow of another filtration layer which is selected from among a wet-laid or a dry-laid filter having a base weight of about 30- 100 g/m 2> and air permeability of about 100-3000 L/m 2>s and thermally bonded non woven having a basis weight of about 10-100 g/m 2> and air permeability of about 100-3000 L/m 2>s. The multipurpose filtration capacity layer is selected from among a wet-laid or a dry-laid high dust capacity paper, high bulk melt blown non woven, spun blown modular paper and micro denier spun bond non woven with basis weight and air permeability of 30-150 g/m 2> and 500-8000 L/m 2> s, 30-180 g/m 2> and 300-1500 L/m 2> s, 20-150 g/m 2> and 200-3000 L/m 2> s and 20-150 g/m 2> and 500-10000 L/m 2>s respectively. The multipurpose filtration layer is operative to provide to the composite structure a pressure drop of at most 30 m bar at fine dust particle loading of at least 6.5 g. The wet-laid high dust capacity paper consists of fibers with at least 15% chargeable or unchargeable synthetic fibers and complementary amount of wood pulp fibers and binder. The synthetic fibers are polyester or electrostatically charged polypropylene. The dry-laid high dust capacity paper of multilayer filtration layer is selected from among latex bonded fluff pulp fibers, thermally bondable-fusing fibers which are bicomponent polymer fibers, thermally bonded blend of thermally bondable fusing polymer fibers and fluff pulp fibers, thermally bonded blend of thermally bondable fusing fibers, fluff pulp fibers and electrostatically charged split film fibers, thermally bonded blend of mixed electrostatic fibers. Electrostatically charged melt blown fleece layer having basis weight of about 10- 50 g/m 2> and air permeability of 100-1500 L/m 2> s is positioned between the multipurpose filtration layer and the other filtration layer. An independent claim is also included for the method of filtering a gas.