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 manufacturing method of a honeycomb structure including: a formed body forming step of extruding a forming raw material, to form a plurality of quadrangular prismatic columnar honeycomb formed bodies; a firing step of firing the honeycomb formed bodies, to form a plurality of quadrangular prismatic-columnar quadrangular segments; a triangular segment forming step to form a triangular prismatic-columnar triangular segment; a bonded body forming step to form a honeycomb bonded body; and a circumference grinding step to manufacture the honeycomb structure, wherein the bonded body forming step further includes: a pressurizing step of pressurizing the triangular segment from a circumferential direction of the temporary assembly toward a central direction thereof, by use of a pressurizing jig comprising a pressurizer.

A pillar-shaped honeycomb structure body of a honeycomb structure includes a circumferential cell structure, a central cell structure and a boundary wall therebetween. On a surface orthogonal to the cells there are a circumferential reinforcing region having the partition wall thicker than a basic partition wall thickness in the circumferential cell structure and existing outside a range of a distance from a centroid of the surface; and at least one of a first boundary reinforcing region having the partition wall thicker than the basic partition wall thickness and existing in a range of a distance from the centroid within a range of the circumferential cell structure and a second boundary reinforcing region having the partition wall thicker than a basic partition wall thickness in the central cell structure and existing outside of a range of a distance from the centroid within a range of the central cell structure.

A ceramic filter having a pillar-shaped honeycomb structure, wherein when observing a plurality of pores from a surface of partition walls with a laser microscope and plotting an equivalent circle diameter (μm) of each pore on an X-axis and a pore depth (μm) of each pore on a Y-axis on a two-dimensional coordinate system, a slope of a regression line (y/x) obtained by a least squares method in a range of 20≤x≤40 is 0 to 0.20, an average value of the pore depth of the plurality of pores is 2.5 μm to 5.0 μm, and a number density of the plurality of pores is 600/mm.sup.2 to 2450/mm.sup.2.

A honeycomb structure comprising a pillar-shaped honeycomb structure body having a porous partition wall disposed so as to surround a plurality of cells, wherein let that A denotes an absolute value of open frontal area (%) in a plane of the honeycomb structure body orthogonal to the extending direction of the cells and P denotes an absolute value of porosity (%) of the partition wall, the honeycomb structure has a value represented by the following expression (1) that is 0.05 to 0.12, let that D denotes an average pore diameter (m) of the partition wall and G denotes a geometric surface area (mm.sup.2/mm.sup.3) of the partition wall, the honeycomb structure has a value represented by the following expression (2) that is 8 to 50 (μm×mm.sup.2/mm.sup.3), and the honeycomb structure has a hydraulic diameter of the cells that is 1.1 mm or more,

(1−A/100)×(1−P/100),  Expression (1)

D×G.  Expression (2)

A honeycomb body for exhaust gas aftertreatment includes a plurality of interconnected metal foils stacked on one another. The honeycomb body has a central first flow channel running in the axial direction of the honeycomb body, as an inflow section, and has a plurality of second flow channels between in each case two mutually adjacent metal foils. The first flow channel is in fluid communication with the second flow channels. The second flow channels formed between two mutually adjacent metal foils run in a straight line and parallel to one another along a radial direction of the honeycomb body.

A method of plugging a honeycomb body is disclosed herein, the method comprising: applying a mask layer to the honeycomb body defining a plurality of channels, wherein the mask layer defines a plurality of holes aligned with the plurality of channels; rotating a roller drum; moving the honeycomb body over the roller drum to define a nip between the roller drum and the honeycomb body; and inserting a plugging cement in the nip between the roller drum and the mask layer such that the roller drum forces the plugging cement through the plurality of holes of the mask layer into the plurality of channels of the honeycomb body.

A honeycomb structure includes a honeycomb segment bonded member including; a plurality of prismatic columnar shaped honeycomb segments; and a bonding layer bonding the segments, wherein one honeycomb segment has a bulge on one side face, extending in an axial direction, another honeycomb segment has a recess on one side face, extending in the axial direction, the one honeycomb segment and the another are disposed adjacent and bonded to each other via the bonding layer with the bulge inserted in the recess, length of the bulge is smaller than length of the one side face of the one honeycomb segment, length of the recess is smaller than length of the one side face of the another honeycomb segment, a base part of the bulge is defined with a bent side face, an angle between an imaginary bottom face and the bent side face of the bulge being 60° or more.

Disclosed is an air filter and a method of manufacture for an air filter which is much more cost effective and provides greater operational effectiveness than state-of-the-art air filters. The air filter includes an outer metallic shell which may be used to attach the filter in line to ducting of a heating, ventilation, and air conditioning (HVAC) system. The filter may further include a filter unit made of activated carbon material. The filter unit may have one or more sections and may have a honeycomb cross section.

A honeycomb structure body has cell walls, inner cells and outer cells, and a boundary partition wall. The inner cells are arranged in a high cell density area and the outer cells are arranged in a low cell density area. A cell density of the high cell density area is higher than a cell density of the low cell density area. Cell reinforced parts are formed at a first intersection part at which the cell walls intersect each other. Boundary reinforced parts are formed at a second intersection part at which the cell walls and the boundary partition wall intersect each other. The honeycomb structure body satisfies a relationship of Sb>Sc, where Sb indicates an average value of a cross sectional area of the overall boundary reinforced parts, and Si indicates an average value of a cross sectional area of the overall inner cell reinforced parts.