Patent ID: 7056568

Claim:
A honeycomb structure formed by bonding a plurality of honeycomb segments into one piece, via a bonding layer, the honeycomb segment having an outer wall, partition walls provided inside the outer wall, and a large number of through-holes divided by the partition walls and extending in the axial direction of the segment, comprising the outer wall and the bonding layer having a relation of d *[( κa/da )+( κc/dc )]≧κ≧ d *[( κa/da )+(κ c/dc )]×0.6 wherein κc (W/mK) and dc (cm) are respectively the thermal conductivity and thickness of the outer wall, κa (W/mK) and da (cm) are respectively the thermal conductivity and thickness of the bonding layer formed on the outer wall, and κ (W/mK) and d (cm) are respectively the thermal conductivity and thickness of a layer which is the sum of the outer wall and the bonding layer; wherein a ratio of the thermal conductivity κs of the honeycomb segment to the thermal conductivity κa of the bonding layer is 5 to 300; and wherein the outer wall is formed by firing of a raw material containing a particulate substance S, and the bonding layer contains a particulate substance A having an average particle diameter of 1/100 to ½ relative to the average particle diameter of the particulate substance S.