CERAMIC HONEYCOMB FILTER AND ITS PRODUCTION METHOD

摘要

A ceramic honeycomb filter including a ceramic honeycomb structure having large numbers of flow paths partitioned by porous cell walls, and plugs disposed in the flow paths alternately on the exhaust gas inlet or outlet side, to remove particulate matter from an exhaust gas passing through the porous cell walls; the porous cell walls having porosity of 45-75%, the median pore diameter A (μm) of the cell walls measured by mercury porosimetry, and the median pore diameter B (μm) of the cell walls measured by a bubble point method meeting the formula of 35<(A−B)/B×100≦70, and the maximum pore diameter of the cell walls measured by a bubble point method being 100 μm or less.

主权项

1. A method for producing a ceramic honeycomb filter comprising the steps of blending a starting material powder comprising a cordierite-forming material containing talc, silica, an alumina source and kaolin, and a pore-forming material to prepare a moldable material; extruding said moldable material to form a honeycomb-shaped molding; and plugging the predetermined flow paths of said honeycomb-shaped molding to form said ceramic honeycomb filter;
said silica having a median diameter of 15-60 μm, said talc having a median diameter of 10-25 μm and a morphology index of 0.77 or more, said kaolin particles having a median diameter of 1-8 μm and a cleavage index of 0.9 or more, said cleavage index being a value expressed by I(002)/[I(200)+I(020)+I(002)], wherein I(200), I(020) and I(002) are the peak intensities of (200), (020) and (002) planes measured by X-ray diffraction, said alumina source having a median diameter of 1-6 μm, said pore-forming material having a median diameter of 30-70 μm, and said cordierite-forming material being classified by passing through a sieve having opening diameters of 250 μm or less.