Mat material, exhaust gas purification device, and method for producing mat material

Abstract

A mat material including: inorganic fibers; and multiple entanglement points formed by needling at least one of a front surface or a back surface of the mat material, wherein a density p of the entanglement points is in a range of 0.5 pcs/cm2≤ρ<18 pcs/cm2, at least one of a 4 mm×4 mm first region without the entanglement points or a 3 mm×8 mm second region without the entanglement points is arranged in a 25 mm×25 mm region, and the mat material contains an inorganic binder and has a shear modulus of 0.20 or more and a post-firing surface pressure of 50 kPa or more.

1 . A mat material comprising:
 inorganic fibers; and   multiple entanglement points formed by needling at least one of a front surface or a back surface of the mat material,   wherein a density ρ of the entanglement points is in a range of 0.5 pcs/cm2≤ρ<18 pcs/cm2, at least one of a 4 mm×4 mm first region without the entanglement points or a 3 mm×8 mm second region without the entanglement points is arranged in a 25 mm×25 mm region, and   the mat material contains an inorganic binder and has a shear modulus of 0.20 or more and a post-firing surface pressure of 50 kPa or more.   
     
     
         2 . The mat material according to  claim 1 ,
 wherein a weight ratio of the inorganic binder to the mat material, i.e., weight of inorganic binder/weight of mat material, is more than 0 wt % and 10 wt % or less.   
     
     
         3 . The mat material according to  claim 1 , further comprising an organic binder. 
     
     
         4 . The mat material according to  claim 3 ,
 wherein a weight ratio of the organic binder to the mat material, i.e., weight of organic binder/weight of mat material, is more than 0 wt % and 10 wt % or less.   
     
     
         5 . The mat material according to  claim 3 ,
 wherein the inorganic binder and the organic binder are attached in an individually dispersed state to a surface of each inorganic fiber.   
     
     
         6 . The mat material according to  claim 1 , further comprising a polymeric dispersant. 
     
     
         7 . The mat material according to  claim 3 ,
 wherein aggregates of the inorganic binder and the organic binder are attached to a surface of each inorganic fiber.   
     
     
         8 . The mat material according to  claim 7 ,
 wherein the surface of each inorganic fiber is at least partially covered with a coating layer containing a mixture of the inorganic binder and the organic binder.   
     
     
         9 . The mat material according to  claim 8 ,
 wherein the coating layer is formed from a continuous flaky mixture of the inorganic binder and the organic binder.   
     
     
         10 . The mat material according to  claim 8 ,
 wherein the coating layer has a stepped shape.   
     
     
         11 . The mat material according to  claim 8 ,
 wherein a particulate mixture of the inorganic binder and the organic binder is attached to a surface of the coating layer.   
     
     
         12 . The mat material according to  claim 1 ,
 wherein the mat material has a shear modulus that is 105% or more of a shear modulus of a mat material with same conditions except that no inorganic binder is contained.   
     
     
         13 . The mat material according to  claim 1 ,
 wherein at least one of the first region or the second region is arranged in a plural number in the 25 mm×25 mm region.   
     
     
         14 . The mat material according to  claim 1 ,
 wherein the mat material is for use in an exhaust gas conversion apparatus.   
     
     
         15 . The mat material according to  claim 1 , further comprising a protective sheet on at least one of the front surface or the back surface. 
     
     
         16 . An exhaust gas conversion apparatus comprising:
 an exhaust gas treatment unit;   a metal casing for housing the exhaust gas treatment unit; and   a mat material arranged between the exhaust gas treatment unit and the metal casing for holding the exhaust gas treatment unit,   wherein the mat material is the mat material according to  claim 1 .   
     
     
         17 . A method for producing a mat material, comprising
 an attaching step of attaching an inorganic binder to an inorganic fiber mass, the inorganic fiber mass including inorganic fibers and multiple entanglement points formed by needling at least one of a front surface or a back surface of the inorganic fiber mass, wherein a density ρ of the entanglement points is in a range of 0.5 pcs/cm2≤ρ<18 pcs/cm2, and at least one of a 4 mm×4 mm first region without the entanglement points or a 3 mm×8 mm second region without the entanglement points is arranged in a 25 mm×25 mm region.   
     
     
         18 . A method for producing a mat material, comprising
 an attaching step of attaching both an inorganic binder and an organic binder to an inorganic fiber mass, the inorganic fiber mass including inorganic fibers and multiple entanglement points formed by needling at least one of a front surface or a back surface of the inorganic fiber mass, wherein a density ρ of the entanglement points is in a range of 0.5 pcs/cm2≤ρ<18 pcs/cm2, and at least one of a 4 mm×4 mm first region without the entanglement points or a 3 mm×8 mm second region without the entanglement points is arranged in a 25 mm×25 mm region.   
     
     
         19 . The method for producing a mat material according to  claim 18 ,
 wherein in the attaching step, a dispersion in which the inorganic binder and the organic binder are dispersed in a dispersion medium is attached to the inorganic fiber mass.   
     
     
         20 . The method for producing a mat material according to  claim 18 ,
 wherein in the attaching step, an aggregated dispersion in which the inorganic binder and the organic binder are aggregated is attached to the inorganic fiber mass.