Patent ID: 8361400

Claim:
A columnar honeycomb structural body, comprising: a porous ceramic block having a plurality of through holes and a wall portion interposed between the through holes, the through holes extending in parallel with one another in a length direction of the porous ceramic block, wherein the through holes have one of ends sealed such that an opening area of one end face of the through holes is larger than an opening area of the other end face of the through holes, the plurality of through holes includes a plurality of large through holes sealed on the one end face and a plurality of small through holes sealed on the other end face, the large through holes have cross-section areas which are larger than cross-section areas of the small through holes, the large through holes and the small through holes are positioned such that the wall portion includes a plurality of partition wall portions each of which is interposed between two adjacent large through holes of the large through holes and a plurality of partition wall portions each of which is interposed between adjacent large through hole and small through hole of the large and small through holes, that each of the partition wall portions between the two adjacent large through holes is defined by two adjacent sides of the two adjacent large through holes, that each of the partition wall portions between the adjacent large and small through holes is defined by two adjacent sides of the adjacent large and small through holes, and that a distance between centers of gravity of the cross-section areas of adjacent ones of the large through holes is set to be equal to a distance between centers of gravity of the cross-section areas of adjacent ones of the small through holes, each of the partition wall portions between the adjacent large and small through holes has a length which is greater than a length of each of the partition wall portions between the two adjacent large through holes, the opening area of the one end face of the through holes and the opening area of the other end face of the through holes have a ratio in a range between 1.01 to 6, the wall portion has a plurality of micro pores having an average pore diameter in a range from 5 to 30 μm, the micro pores include large micro pores having a pore diameter two or more times larger than the average pore diameter, and the large micro pores have a capacity of which a rate is set to 30% or less of a capacity of the micro pores in entirety.