Production process of a hexagonal honeycomb structure

Abstract

The present invention provides a production process of a hexagonal honeycomb structure having low deformation of hexagonal cells. This process comprises an extrusion step for obtaining moldings ( 7 ) in which partitions ( 71 ) are provided in the form of a hexagonal matrix by extrusion molding of a mixed raw material using a horizontal extruder having an extrusion die provided with slits in the form of a hexagonal matrix and in which the direction of extruding is substantially the horizontal direction, a drying step for drying moldings ( 7 ), and a baking step for baking moldings ( 7 ). The extrusion step is performed such that c axis ( 700 ) parallel to two parallel sides ( 702 ) and ( 705 ) of the six sides ( 701 ) through ( 706 ) of each hexagon formed by partitions ( 71 ) of extruded moldings ( 7 ) is substantially vertical relative to the horizontal plane.

1 . A production process of a hexagonal honeycomb structure in which a large number of hexagonal cells are provided surrounded by partitions in the form of a hexagonal matrix comprising: 
 an extrusion step for obtaining moldings in which partitions are provided in the form of a hexagonal matrix by extrusion molding of a mixed raw material using a horizontal extruder having an extrusion die provided with slits in the form of a hexagonal matrix and in which the direction of extruding is substantially the horizontal direction,    a drying step for drying said moldings, and    a baking step for baking said moldings,    wherein two of the six sides of each hexagon in a cross-section, in which said partitions of the extruded moldings are formed in the above-mentioned extrusion step and which is perpendicular to said direction of extrusion of said honeycomb structure, are parallel, and c axis parallel to these sides is substantially vertical relative to the horizontal plane.    
     
     
         2 . A production process of a hexagonal honeycomb structure according to  claim 1 , wherein said c axis of moldings obtained in said extrusion step is within the range of ±10° from the vertical direction.  
     
     
         3 . A production process of a hexagonal honeycomb structure according to  claim 1 , wherein in addition to at least one of either of said drying step or said baking step being performed horizontally while maintaining the lengthwise direction of said moldings substantially in the horizontal direction, said c axis of said moldings is facing in the substantially vertical direction relative to the horizontal plane.  
     
     
         4 . A production process of a hexagonal honeycomb structure according to  claim 1 , wherein when transporting or storing said moldings between any of said extrusion step, drying step or baking step, together with placing the moldings horizontally so that the lengthwise direction of said moldings is maintained substantially in the horizontal direction, said c axis of said moldings is facing in the substantially vertical direction relative to the horizontal plane.  
     
     
         5 . A production process of a hexagonal honeycomb structure in which a large number of hexagonal cells are provided surrounded by partitions in the form of a hexagonal matrix comprising: 
 an extrusion step for obtaining moldings in which partitions are provided in the form of a hexagonal matrix by extrusion molding of a mixed raw material using an upright extruder having an extrusion die provided with slits in the form of a hexagonal matrix and in which the direction of extruding is substantially the vertical direction,    a drying step for drying said moldings, and    a baking step for baking said moldings,    wherein in at least one of either said drying step or said baking step, in addition to placing horizontally so that the lengthwise direction of said moldings is maintained substantially in the horizontal direction, two of the six sides of each hexagon in a cross-section in which said partitions of the extruded moldings are formed and which is perpendicular to said direction of extrusion of said honeycomb structure are parallel, and c axis parallel to these sides is substantially vertical relative to the horizontal plane.    
     
     
         6 . A production process of a hexagonal honeycomb structure according to  claim 5 , wherein when transporting or storing said moldings between any of said extrusion step, drying step or baking step, together with placing the moldings horizontally so that the lengthwise direction of said moldings is maintained substantially in the horizontal direction, said c axis of said moldings is facing in the substantially vertical direction relative to the horizontal plane.  
     
     
         7 . A production process of a hexagonal honeycomb structure in which a large number of hexagonal cells are provided surrounded by partitions in the form of a hexagonal matrix comprising: 
 an extrusion step for obtaining moldings in which partitions are provided in the form of a hexagonal matrix by extrusion molding of a mixed raw material using a horizontal extruder having an extrusion die provided with slits in the form of a hexagonal matrix and in which the direction of extruding is substantially the horizontal direction,    a drying step for drying said moldings, and    a baking step for baking said moldings,    wherein two of the sides of each hexagon in a cross-section, in which said partitions of the extruded moldings are formed in the above-mentioned extrusion step and which is perpendicular to said direction of extrusion of said honeycomb structure, are parallel, and the orientation of c axis parallel to these sides is in a direction that differs by 60-120° from the orientation of c axis of said moldings in the case of placing said moldings horizontally in at least one of either of said drying step or said baking step so that the lengthwise direction of said moldings is maintained substantially in the horizontal direction.