PURPOSE: To reduce a pressure drop and to improve a collection efficiency of a filter by blending a spirally crimped eccentric sheath-core type or side-by- side type composite polyester fiber and a thermoadhesive binder fiber in a specified ratio and by getting a paper made of the aforementioned materials to have a specified bulk density.
CONSTITUTION: A wet paper is taken up from an aqueous suspension containing 30wt.% or more spirally crimped eccentric sheath-core type or side-by-side type composite polyester fiber and 5wt.% or more binder fiber, which becomes thermoadhesive at 200°C or lower, and it is made a filter paper of 0.06g/cm3 or less in bulk density under a load of 2.5g/cm2 by a heat treatment at 130 to 180°C In spite of a wet process, it is possible, as a result, to produce a filter paper usable for coarse dust, and moreover to produce a filter paper of a low pressure drop, a high dust collection efficiency and a long filtration life as a medium performance filter. Furthermore, it is possible to use a low cost raw material of staple fibers, because the production method is a wet process.
HIRAMATSU KENJI
EZAKI TAMEMARU
