A particulate filter, including: a pillar-shaped honeycomb structure portion having a plurality of first cells extending from a first end face to a second end face, the first end face being open and the second end face being plugged, and a plurality of second cells extending from the first end face to the second end face, the first end face being plugged and the second end face being open, in which the first cells and the second cells are alternately arranged adjacent to each other with porous partition walls interposed therebetween; and a low thermal conductive layer covering a part or the whole of an outer peripheral side surface of the pillar-shaped honeycomb structure portion, the thermal conductivity in a thickness direction of the low thermal conductive layer being 0.6 W/(m.Math.K) or less.

An outer periphery coating material being coated onto an outer peripheral surface of a ceramic honeycomb structure to form an outer periphery coated layer. The outer periphery coating material comprises: a particle mixture containing cordierite particles and amorphous silica particles in a mass ratio of from 40:60 to 80:20; and from 10 to 30% by mass of crystalline inorganic fibers in an outer percentage relative to the particle mixture. An average particle diameter of the cordierite particles is different from an average particle diameter of the amorphous silica particles.

A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall so as to surround a plurality of cells extending from a first end face to a second end face, and a circumferential coating layer composed of a circumferential coating material coated on at least a part of circumference of the honeycomb structure body, wherein the circumferential coating layer has a printing area for printing on the surface thereof, the printing area has a lightness (L*) in L*a*b* color space (CIE1976) defined by International Commission on Illumination (CIE) of 35 or more, and the printing area has a surface roughness Ra of 30 μm or less.

A circumferential coating material to be applied to a circumferential surface of a honeycomb structure made of ceramics formed by extrusion, the circumferential coating material including a ceramic raw material that forms a circumferential coating layer, wherein the ceramic raw material contains: a ceramic mixture of first ceramic particles having particulate shapes, and second ceramic particles having particulate shapes and an average particle diameter different from an average particle diameter of the first ceramic particles; and a fiber material having an elongated strip-like shape, wherein the ceramic mixture has particle size distribution including at least two local maximum values, and the fiber material has an average fiber length ranging from 30 to 100 μm in a longitudinal direction.

A method to form a laminar integral skin of a honeycomb structure is provided. The method includes extruding a ceramic precursor batch through a die with feedholes in entry side and slots in exit face of the die to form the honeycomb structure. In a region on the periphery of the die configured to form the cell matrix, a series of concentric slots around the matrix in the exit face of the die are configured to feed skin onto the matrix. Ring sections between concentric slots are angled away from the center and a mask is disposed on top of the periphery producing a channel for extruded skin to meet and bond to extruded matrix. Optionally, slots in the skin-forming ring sections enhance knitting between laminar skin layers. The die and honeycomb body having uniform integral skin are also provided.

An exhaust gas purification filter includes a cell assembly including cells and a partition wall, seal members, and a skin member. The partition wall has a porosity of 50% to 70%. The skin member has a thickness T of 0.3 mm to 1.0 mm. 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 of the outer periphery is rounded to have a value of radius of curvature R being 0.02 mm to 0.6 mm A degree of distortion δ being a degree of change in the external dimensions of the filter in axial direction, is greater than 0 and is 1.5 mm or less. A value of a structural variable X, expressed by Equation 1 below, is 0.05 to 6, X=T×R/δ . . . Equation 1.

Honeycomb bodies and methods for treating a honeycomb bodies that include a skin surrounding a matrix of cells, the skin and the matrix of cells comprising a porous inorganic material. Methods include applying a buffer solution to only the porous inorganic material of the skin and coating the porous inorganic material of the skin with an oxide slurry. The oxide slurry includes an oxide or a precursor of the oxide configured to increase the isostatic strength of the honeycomb body. After treatment, the honeycomb body may be dried.

A ceramic honeycomb body having a skin that does not block partial cells extending from an inlet face to an outlet face at an outer periphery portion of the body. A method of making the ceramic honeycomb body having the skin includes disposing a sheet on an outer peripheral wall of a honeycomb core having an outer surface spaced apart from interiors of the partial cells and skinning the body having the sheet disposed thereon. Subsequent curing in the method bonds the skin to cell walls of the body spaced apart from interiors of the partial cells.

A filter including a plurality of pillar-shaped honeycomb structure segments made of porous ceramics, side faces of the segments being bonded together via a bonding material, wherein each of the pillar-shaped honeycomb structure segments includes an outer peripheral side wall, and partition walls partitioning a plurality of cells extending from a first end face to a second end face, and in each of the pillar-shaped honeycomb structure segments, an average porosity of the outer peripheral side wall is lower than that of the partition walls.

A ceramic honeycomb body having a skin that does not block partial cells extending from an inlet face to an outlet face at an outer periphery portion of the body. A method of making the ceramic honeycomb body having the skin includes disposing a sheet on an outer peripheral wall of a honeycomb core having an outer surface spaced apart from interiors of the partial cells and skinning the body having the sheet disposed thereon. Subsequent curing in the method bonds the skin to cell walls of the body spaced apart from interiors of the partial cells.