A pillar shaped honeycomb structure includes: a porous partition wall that defines a plurality of cells, the cells forming flow paths for a fluid, the cells extending from an inflow end face to an outflow end face; and an outer peripheral wall located at the outermost circumference. The cells include: a plurality of cells A wherein a side of the inflow end face is opened and the outflow end face has a plugged portion; and a plurality of cells B wherein a side of the outflow end face is opened and the inflow end face has a plugged portion, the cells B being arranged alternately with the cells A. One or both of the plugged portion of the cells A and the plugged portions of the cells B contain a magnetic substance and glass.

An exhaust gas purification filter includes a cell assembly including cells each having a quadrangular cross-sectional shape and a partition wall, seal members, and a skin member. The partition wall has a porosity P1 of 50% to 70%, and the skin member has a porosity P2 of 50% to 70%, the porosity P1 and the porosity P2 satisfy a relationship P1<P2. A difference between the porosity P2 and the porosity P1 is 20% or less. The partition wall includes crossing portions, each cell has at least one part of an outer periphery defined by a corresponding one of the crossing portions, the at least one part is rounded to have a radius of curvature R, each cell has a radius r of a hydraulic diameter, the radius of curvature R and the radius r of the hydraulic diameter satisfy a relationship 0.2<R [mm]/r [mm]<1.

A honeycomb body comprises a matrix of intersecting porous walls forming channels. Plugs are disposed in a percentage of the channels having the second hydraulic diameter, wherein the percentage of the channels of the second diameter having a plug is less than or equal to 15%. In some embodiments, some of the channels have a first hydraulic diameter and others have a second hydraulic diameter that is smaller than the first hydraulic diameter, and may be unplugged for plugged. The porous walls can further comprise a transverse thickness of the walls Tw less than or equal to 0.20 mm, a channel density CD greater than or equal to 62 channels per cm.sup.2, an average bulk porosity % P greater than or equal to 50%, and a median pore diameter d.sub.50 ranging from between 4.0 μm and 30.0 μm.

Disclosed is a honeycomb filter for collecting fine particles that includes a wall portion formed from a base material containing ceria-zirconia composite oxide and an inorganic binder. The wall portion has a gas permeability coefficient of 1.0 μm.sup.2 or greater and 3.0 μm.sup.2 or less.

A honeycomb filter includes a honeycomb structure body that has porous partition walls disposed so as to surround cells, and plugging portions that are disposed at any one of the ends on the inflow end face and the ends on the outflow end face. A cross-sectional shape of each of the inflow cells is octagonal and a cross-sectional shape of each of the outflow cells is quadrangular. An area ratio (S1/S2) of a cross-sectional area S2 of each of the outflow cells to a cross-sectional area S1 of each of the inflow cells is 1.40 to 2.20. The plugging portions have convex portions that protrude from the end faces on which the plugging portions are disposed, toward the outer sides, and have a protruding height H of 0.3 to 3.0 mm, and the plugging portions have a plugging depth L of 4.0 to 9.0 mm.

A cement mixture for applying to a ceramic honeycomb body that includes: (i) inorganic ceramic particles; (ii) an inorganic binder; (iii) an organic binder containing a hydrophilic polymer and a hydrophilic additive comprising a polymer with a different composition than the composition of the hydrophilic polymer, the additive having a weight average molecular weight (M.sub.w) of at least 1,000,000 g/mol; and (iv) an aqueous liquid vehicle.

A honeycomb filter comprising a pillar-shaped honeycomb structure body having a porous partition wall and a plugging portion, wherein, in a pore diameter distribution of the partition wall, in the case where the pore diameter (.Math.m) whose cumulative pore volume is 10% of the total pore volume is denoted by D10, the pore diameter (.Math.m) whose cumulative pore volume is 50% of the total pore volume is denoted by D50, and the pore diameter (.Math.m) whose cumulative pore volume is 90% of the total pore volume is denoted by D90, all of the following equations (1) to (6) are satisfied.

[00001]$\begin{array}{cc}\text{8}\text{.4}\mu \text{}\text{m<D10}& \text{­­­(1)}\end{array}$

[00002]$\begin{array}{cc}\text{17}\text{.5}\mu \text{}\text{m<D50<24}\text{.0}\mu \text{}\text{m}& \text{­­­(2)}\end{array}$

[00003]$\begin{array}{cc}\text{D90<55}\text{.2}\mu \text{}\text{m}& \text{­­­(3)}\end{array}$

[00004]$\begin{array}{cc}\left(\text{logD90-logD10}\right)/\text{logD50}\text{<0}\text{.60}& \text{­­­(4)}\end{array}$

[00005]$\begin{array}{cc}\text{logD90}/\text{logD50}\text{<1}\text{.30}& \text{­­­(5)}\end{array}$

[00006]$\begin{array}{cc}\text{logD50}/\text{logD10}\text{<1}\text{.38}& \text{­­­(6)}\end{array}$

A porous ceramic honeycomb body (10) including intersecting walls that form channels (22) extending axially from a first end face to a second end face and layered plugs (62) comprised of a first layer (64) disposed on channel walls and a second layer (66) disposed inward toward an axial center of each respective channel on the first layer. The plugs seal at least one of a first portion of the channels at the first end face and a second portion of channels at the second end face of the porous ceramic honeycomb body.

A honeycomb filter includes a pillar-shaped honeycomb structure having porous partition walls provided, surrounding a plurality of cells which serve as fluid through channels extending from an inflow end face to an outflow end face, and porous plugging portions provided either at the ends on the inflow end face or the outflow end face of the cells, wherein the plugging portions are composed of a porous material, the honeycomb structure has a central region and a circumferential region, and a ratio of an area of the circumferential region with respect to that of the central region ranges from 0.1 to 0.5, a plugging length L1 in the cell extending direction of a central plugging portion in the central region is larger than a plugging length L2 of a circumferential plugging portion in the circumferential region, L1 ranges from 7 to 9 mm, and L2 from 3 to 6 mm.

An exhaust gas purification filter includes a plurality of cells extending in a filter axial direction, a porous partition separating and defining the plurality of cells, and a sealing section sealing the plurality of cells alternately at both filter ends. In the exhaust gas purification filter, the partition has a void volume of a reduced dale, Vvv, and a material volume of a reduced peak, Vmp, as volume parameters determined in noncontact surface roughness measurement on a surface of the partition, with their total value being 1.8 μm.sup.3/μm.sup.2 or less.