| 摘要 |
PROBLEM TO BE SOLVED: To provide an air permeability adjusting sheet having good sound absorption performance even to noise in a wide frequency range and capable of providing a light weight sound absorber.SOLUTION: An air permeability adjusting sheet 2 is manufactured by forming a porous Sirasu balloon dispersed polyvinyl alcohol coated film 22 having mass per unit area of 10 g/mto 50 g/mon one surface of an unwoven fabric 21, excluding one formed by needle-punching, by flow distribution coating, and adjusting air permeability resistance in a range of 0.2 kPa s/m to 3.0 kPa s/m, and a sound absorber is obtained by adhering the air permeability adjusting sheet 2 to a surface of a porous substrate 1 by directing a forming side of the porous Sirasu balloon dispersed polyvinyl alcohol coated film 22 to the porous substrate 1.SELECTED DRAWING: Figure 1 |
