Exhaust gas purifying filter with reinforced peripheral area and method for manufacturing the same

Abstract

An exhaust gas purifying filter having a high strength and an excellent efficiency of exhaust gas purification and a method for manufacturing the same are provided. An exhaust gas purifying filter 1 comprises a ceramic honeycomb structure 2 having a surrounding wall 21, partition walls 22 provided in a honeycomb pattern within the surrounding wall 21, and a plurality of cells 23 partitioned by the partition walls 22 and penetrating through end faces 241, 242. If a virtual line 3 is drawn on the end faces 241, 242 of the structure 2 by continuously connecting points at a distance of 1.0 to 3.0 times the cell pitch in the direction toward the center from an inner surface 211 of the surrounding wall 21, not less than 90% of a peripheral area 25 outside the virtual line 3 is blocked with plug material 4.

1 . A method for manufacturing an exhaust gas purifying filter comprising: 
 a forming process for forming a ceramic honeycomb structure having a surrounding wall, partition walls provided in a honeycomb pattern within the surrounding wall, and a plurality of cells partitioned by the partition walls and, at the same time, penetrating through from one end face of the ceramic honeycomb structure to the other;    a masking process for pasting mask tapes to the entire end faces of the ceramic honeycomb structure;    a drilling process in which a virtual line is drawn by continuously connecting points at a distance of 1.0 to 3.0 times the pitch of the cells in the direction toward the center from the inner surface of the surrounding wall, and at least the mask tape pasted to the openings of the cells through which the virtual line passes and the openings of the cells outside the virtual line is drilled; and    a plugging process in which not less than 90% of the peripheral area outside the virtual line is blocked with plug material after dipping the end faces into the plug material paste and forming the plug material in the openings of the cells other than those blocked with the mask tape.    
   
   
       2 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 1 , wherein as for part of the mask tape pasted to the openings of the cells within the virtual line, the part of the mask tape pasted to one of two neighboring openings of the cells is drilled in the drilling process.  
   
   
       3 . A method for manufacturing an exhaust gas purifying filter comprising: 
 a forming process for forming a ceramic honeycomb structure having a surrounding wall, partition walls provided in a honeycomb pattern within the surrounding wall, and a plurality of cells partitioned by the partition walls and, at the same time, penetrating through from one end face of the ceramic honeycomb structure to the other;    a masking process in which a virtual line is drawn on the end face of the ceramic honeycomb structure by continuously connecting points at a distance of 1.0 to 3.0 times the pitch of the cells in the direction toward the center from the inner surface of the surrounding wall and a mask tape is pasted to the central area within the virtual line; and    a plugging process in which not less than 90% of the peripheral area outside the virtual line is blocked with plug material after dipping the end faces into the plug material paste and forming the plug material in the openings of the cells other than those blocked with the mask tape.    
   
   
       4 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 3 , wherein the drilling process is carried out for drilling at least the mask tape covering the openings of the cells through which the virtual line passes after the making process and before the plugging process.  
   
   
       5 . A method for manufacturing an exhaust gas purifying filter comprising: 
 a forming process for forming a ceramic honeycomb structure having a surrounding wall, partition walls provided in a honeycomb structure within the surrounding wall, and a plurality of cells partitioned by the partition walls and, at the same time, penetrating through from one end face of the ceramic honeycomb structure to the other;    a masking process for pasting mask tapes to the entire end faces of the ceramic honeycomb structure;    a cutting process in which a virtual line is drawn on the end face by continuously connecting points at a distance of 1.0 to 3.0 times the pitch of the cells in the direction toward the center from the inner surface of the surrounding wall, and the mask tape pasted to the peripheral area outside the virtual line is cut and removed; and    a plugging process in which not less than 90% of the peripheral area outside the virtual line is blocked with plug material after dipping the end faces into the plug material paste and forming the plug material in the openings of the cells other than those blocked with the mask tape.    
   
   
       6 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 5 , wherein a drilling process is carried out for drilling at least the mask tape covering the openings of the cells through which the virtual line passes after the cutting process and the before the plugging process.  
   
   
       7 . A method for manufacturing an exhaust gas purifying filter comprising: 
 a forming process for forming a ceramic honeycomb structure having a surrounding wall, partition walls arranged in a honeycomb pattern within the surrounding wall, and a plurality of cells partitioned by the partition walls and, at the same time, penetrating through from one end of the ceramic honeycomb structure to the other;    a masking process for pasting mask tapes to the entire end faces of the ceramic honeycomb structure;    a cutting process in which a virtual line is drawn on the end face by continuously connecting points at a distance of 1.0 to 3.0 times the pitch of cells in the direction toward the center from the inner surface of the surrounding wall, and the mask tape is cut along the partition walls of the cells through which the virtual line passes and, at the same time, the mask tape outside the virtual line is removed; and    a plugging process in which not less than 90% of the peripheral area outside the virtual line is blocked with plug material after dipping the end faces into the plug material paste and forming the plug material in the openings of the cells other than those blocked with the mask tape.    
   
   
       8 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 3 , wherein as for the mask tape pasted to the openings of the cells within the virtual line, the mask tape pasted to one of two neighboring openings of the cells is drilled after the masking process and before the plugging process.  
   
   
       9 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 5 , wherein as for the mask tape pasted to the openings of the cells within the virtual line, the mask tape pasted to one of two neighboring openings of the cells is drilled after the masking process and before the plugging process.  
   
   
       10 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 7 , wherein as for the mask tape pasted to the openings of the cells within the virtual line, the mask tape pasted to one of two neighboring openings of the cells is drilled after the masking process and before the plugging process.  
   
   
       11 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 1 , wherein the virtual line is a line drawn by continuously connecting points at a distance of 1.0 to 2.0 times the pitch of the cells in the direction toward the center from the inner surface of the surrounding wall.  
   
   
       12 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 1 , wherein the partition wall has a thickness of 0.25 to 0.40 mm.  
   
   
       13 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 3 , wherein the virtual line is a line drawn by continuously connecting points at a distance of 1.0 to 2.0 times the pitch of the cells in the direction toward the center from the inner surface of the surrounding wall.  
   
   
       14 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 3 , wherein the partition wall has a thickness of 0.25 to 0.40 mm.  
   
   
       15 . A method for manufacturing an exhaust gas purifying filter, as set forth in  claim 5 , wherein the virtual line is a line drawn by continuously connecting points at a distance of 1.0 to 2.0 times the pitch of the cells in the direction toward the center from the inner surface of the surrounding wall.