| 摘要 |
PURPOSE:To improve the sound absorbing effect of a sound absorbing material in a low frequency band by holding powder in air gaps among fibers via a foamable resin binder, and foaming the binder at a temperature of a foaming temperature or higher. CONSTITUTION:A woody fiber having a fiber size of 50mum as fiber 1, vermiculite having a particle size of 250mum or less as powder 2 and a foamable phenol resin fine powder as foamable resin binder 3 are mixed, formed in a mat state, and heated at 130 deg.C for several minutes to foam and cure the fine particles to be a sound absorbing material. The ratio of the materials of the fiber 1, the powder 2 and the binder 3 is, by weight, 60, 34 and 6. Thus, the fibers 1 and between the fiber 1 and the powder 2 are rigidly adhered and held by the binder 3 to improve the sound absorbing ratio of the low frequency band due to the presence of the gap 4 among the fibers 1 and the powder 2. |
