| 摘要 |
An expansion-molded article (foamed body) produced by using foamed and expanded beads, and having open voids has sound absorbing qualities, and can be used as a sound absorbing material. A sound absorbing material which is able to attain a high sound absorption coefficient in a wide acoustic frequency range is provided by a molded article produced by using resin particles, having through hole(s) and a porosity of 45 to 80% in a most densely packed state. The void content of the molded article is 10 to 60%, and the bulk density thereof is 0.01 to 0.6 g/cm<3>. The molded article has not less than 3 continuous center frequency measuring points at which the sound absorption coefficient is at least 70%, and not less than 7 continuous center frequency measuring points at which the sound absorption coefficient is at least 50% in the sound absorption coefficients at the center frequencies of 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, 2500 and 3150 (Hz) as determined by the measuring method of reverberant absorption coefficient prescribed in JIS A 1409.
|
