| 摘要 |
PURPOSE:To prevent deterioration of frequency characteristic and improve tone quality by using epoxy resin of specific chemical constitutional formula and highly elastic fiber for the diaphragm for a speaker especially for a diaphragm substantially composed of highly elastic fiber such as carbon fiber etc. and thermosetting resin. CONSTITUTION:Thermosetting resin that can give large internal loss without damaging other characteristics required to a diaphragm is adopted in place of bisphenol A type epoxy resin so far frequently used. The diaphragm is substantially composed of epoxy resin having chemical constitutional formula shown by the formula I and highly elastic fiber. For instance, when epoxy resin having chemical constitutional formula I and conventional bisphenol A type epoxy resin are impregnated in PAN group carbon fiber nonwoven fabric (basis weight 30g) respectively, heated and pressed in the same condition (hardening temperature 150 deg.C, press pressure 5kg/cm<2>, time 15min), and planar products of the same thickness are compared, it is known that internal loss of the diaphragm can be increased remarkably despite increase of Young's modulus and decrease of density, and can suppress occurrence of harmful peak and dip in high resonance frequency band.
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