Patent ID: 8038953

Claim:
A mat material comprising: inorganic fibers; and plural first and second needle traces formed by a needling process, wherein the first needle traces extend from a first surface toward a second surface and the second needle traces extend from the second surface toward the first surface, wherein at least one of the first needle traces that extends from the first surface has a penetration depth D which is greater than one half of a thickness of the mat material and smaller than the thickness of the mat material, wherein at least one of the second needle traces that extends from the second surface reaches a depth greater than a value obtained by subtracting the penetration depth D from the thickness of the mat material, wherein there is no protrusion of an inorganic fiber bundle at a position on the second surface that lies on a line extending from a first needle trace extending from the first surface, wherein there is no protrusion an inorganic fiber bundle at a position on the first surface that lies on a line extending from a second needle trace extending from the second surface, and wherein for a mat thickness P greater than 10 mm, the penetration depth D of the first needle traces is in the range of 0.6P≦D≦0.8P, and wherein for a mat thickness P less than or equal to 10 mm, the penetration depth D of the first needle traces is in the range of 0.6P≦D≦0.7P.