A honeycomb structure including a plurality of porous honeycomb block bodies bound via joining material layers A. Each of the porous honeycomb block bodies includes a plurality of porous honeycomb segments bound via joining material layers B, each of the porous honeycomb segment includes: partition walls that defines a plurality of cells to form flow paths for a fluid, each of cells extending from an inflow end face that is an end face on a fluid inflow side to an outflow end face that is an end face on a fluid outflow side; and an outer peripheral wall located at the outermost periphery. At least a part of the joining material layers A has higher toughness than that of the joining material layers B.

A method for producing a honeycomb structure for fine particle collection filters. The honeycomb structure includes a plurality of porous honeycomb segments joined together via joining material layers. The method includes the steps of: forming the outer peripheral wall of each of the porous honeycomb segments so as to have a thickness thicker by a grinding margin; drying the porous honeycomb segments each formed by grinding the outer peripheral wall so as to have the thickness thicker by the grinding margin; firing the dried porous honeycomb segments; grinding and removing the grinding margin of the outer peripheral wall of each of the fired porous honeycomb segments; and applying a joining material to each of the porous honeycomb segments with the grinding margin ground and removed, between joining surfaces of each of the porous honeycomb segments, to join the porous honeycomb segments via the joining material layers.

A honeycomb structure includes a plurality of prismatic columnar shaped honeycomb segments; a bonding layer bonding side faces of the honeycomb segments; and a circumferential wall disposed to surround a honeycomb segment bonded body having the honeycomb segments arranged in a grid pattern and bonded with the bonding layer, wherein the honeycomb segments has a porous partition wall disposed to surround a plurality of cells, the cells in other than outermost circumference have a hexagonal shape in a section orthogonal to the cell extending direction, the honeycomb segments include first and second honeycomb segment, the second honeycomb segment is different from the first in at least one of: a shape in the section; a size; and an arrangement direction of the cells and an extended line of one diagonal line imaginarily depicted in the cells in the first honeycomb segment and that in the second are configured to be orthogonal.

A method for producing a honeycomb structure for fine particle collection filters, the honeycomb structure including a plurality of porous honeycomb structure segments. The method includes joining each of the porous honeycomb segments via a joining material layers by applying a joining material between joining surfaces of each of the porous honeycomb structure segments, through a nozzle portion of a joining material applicator. The nozzle portion of the joining material applicator includes: a joining material introduction port; a joining material discharge space; and a joining material flow path having a bent portion, through which the joining material passes from the joining material introduction port to the joining material discharge space. The joining material flow path of the nozzle portion includes a buffer space configured such that a flow path cross section gradually expands toward the joining material discharge space on a downstream side of the bent portion.

The plugged honeycomb structure includes a plurality of honeycomb segments, a bonding layer, and plugging portions which plug open ends of cells of each honeycomb segment, and in the honeycomb segment, at least two types of cells having different sectional shapes are formed to constitute predetermined repeated arrangement patterns, and a ratio of a value R2s obtained by dividing an average sectional area S2.sub.in of inflow cells by an average sectional area S2.sub.out of outflow cells in a partial rim circumferential wall cell region is in a range of 1.7 times or more and 2.0 times or less to a value R1s obtained by dividing an average sectional area S1.sub.in of the inflow cells by an average sectional area S1.sub.out of the outflow cells in a whole rim partition wall cell region.

A filter element for adsorbing harmful gases from a fluid flow includes: a frame and a plurality of filter bodies arranged at a distance next to one another in the frame. A respective filter body has a plurality of openings. A respective filter body is connected to at least one other of the filter bodies via a respective contact element configured for electrical dissipation. The filter bodies are arranged in matrix form, the filter bodies are formed as honeycomb bodies, and/or the filter bodies comprise activated carbon.

A honeycomb filter includes a plugged honeycomb structure body which has cell rows arranged along one direction in a cross section of the honeycomb structure body and including a first cell row constituted of at least one of an inflow cell and an outflow cell, and a through-cell, and a second cell row including no through-cells. A width P1 (mm) of the first cell row, a width P2 (mm) of the second cell and a curvature radius R of a curved shape of corner portions of a polygonal shape of each cell satisfy relations of Equations (1) and (2) below: Equation (1): 2100(P1/P2100)50, and Equation (2): 0.4(R/1000)/((P1+P2)/2)10020.

A plugged honeycomb structure includes: a plurality of honeycomb segments, a bonding layer, and a plugging portions to plug open ends of cells of each of the honeycomb segments. The honeycomb segment is configured so that the cells having at least two kinds of different shapes are disposed in a cross section orthogonal to an extension direction of the cells, the honeycomb segment has a center region and an circumferential region located in the circumference of the center region, the center region has a cell arrangement pattern such that inflow cells surround one outflow cell, in the inflow end face of the honeycomb segment, the circumferential region has an open frontal area that is smaller than an open frontal area of the center region, the segment circumferential wall of the honeycomb segment and the bonding layer have a special thickness.

A compound honeycomb body comprising a first honeycomb section having a volume V1 and a second honeycomb section fluidly connected to the first honeycomb having a volume V2 is provided. The first honeycomb section comprises a low mass high porosity porous ceramic substrate. The second honeycomb section comprises a standard porous ceramic substrate. Wherein V1/V2 comprises a ratio in a range from about 50/50 to about 10/90.

A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall. The honeycomb structure body includes a plurality of cells defined by the partition wall so as to extend from a first end face to a second end face of the honeycomb structure body, the partition wall is formed by a porous body including a silicon phase as a main phase and an oxide, and the oxide includes a first oxide made of an alkali earth metal oxide, Al.sub.2O.sub.3, and SiO.sub.2.